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Chapter4

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The definition statements of the previous chapter are used to define the components of the system and the relationships between the various components. Before the system can be analyzed, however, it is necessary to supply the numeric data appropriate to each of the entities defined. This is the purpose of the DATA statements presented in this chapter.

Each of the DATA statements begins with the keyword DATA followed by a separator. The second word of each DATA statement is also treated as a keyword, instructing the IMP system to interpret the remainder of the statement according to one of the following formats:


Contents

The DATA LINK Statement

The DATA LINK statement specifies the numeric data which locate one of the coordinate systems attached to one of the links relative to the absolute (global) frame of reference for the system.

The DATA LINK statements, taken together with the DATA statements for the various joint types (DATA SPHERE statements, etc.), describe the relative locations of the various links and joints of the system at the initial (design) position.

The initial location of one local coordinate system, attached to one of the links is defined by each DATA LINK statement by specifying the global coordinates of three points (see figure). The first point must lie at the origin of the local coordinate system; the second point must be chosen on the local positive w or z axis; the third point should lie on the positive u or x axis of the local u,v,w coordinate system attached to the joint element or the local x,y,z coordinate system attached to the link.

Format

There are two forms of the DATA LINK statement.

The first form is used to specify the location of one local coordinate system attached to an element of a joint. The format is

DATA LINK(link name,joint name) = x1,y1,z1; x2,y2,z2; x3,y3,z3

where link name and joint name are the alphanumeric names of the link and joint to which this local coordinate system is attached. The xi,yi,zi groups are numeric values for the global coordinates of the three points defining the initial location of a local (u,v,w) joint element coordinate system.

The second form is identical to the first except the joint name is replaced by the keyword LINK. This format is:

DATA LINK (link name, LINK) = x1,y1,z1; x2,y2,z2; x3,y3,z3

which indicates that the primary local coordinate system for the link name is being located.

Examples

DATA LINK (BAR,PIN) = -1.0,2.5,0.0; -1.0,3.5,0.0; -2.0,2.5,1.0

specifies the location of a joint named PIN at one end of a link named BAR. The numeric data corresponds approximately to the figure.

The above example might also take any of the following forms:

DATA LINK (BAR, PIN) = -1,2.5,0; -1,3.5,0; -2,2.5,1
DATA LINK (BAR, PIN) = -1,2.5, ; -1,3.5, ; -2,2.5,1
DATA LINK (BAR, PIN) = PT1; PT2; -2,2.5,1

Notes

  1. When a link name is first defined in the system model (whether by a LINK statement or by a joint definition statement) a local coordinate system for the link is formed in the system memory. This link coordinate system is initially located coincident with the global coordinate system, but may be moved to another location by the LINK form of the DATA LINK statement.
  2. When a joint name is first defined by a joint definition statement, two local joint coordinate systems are formed in the system memory, one attached to each of the two link names joined by the joint. These are initially placed coincident with the local coordinate systems of the two link names, but each may be moved to some other location on the link by the joint name form of the DATA LINK statement.
  3. If the joint name form is used, both link name and joint name must have been used in the same previous statement defining that joint. If not, the DATA LINK statement is ignored and a message is printed.
  4. When the joint name form is used, global coordinate data are given by the user for the xi,yi,zi groups. However, this is converted in memory to a (u,v,w) or (u,v,w) location for that joint name element with respect to the specified link name. This data is then considered fixed; if the link is moved, the joint elements move in unison with it.
  5. When the LINK form is used, the local coordinate system of the link is moved to another location as specified by the xi,yi,zi data. Any data referenced to the link coordinate system (such as the locations of local joint coordinate systems, any points attached to the link, any geometric shape data from a SHAPE statement, etc.) all move if the local link coordinate system is moved by the LINK form of a DATA LINK statement.
  6. If more than one DATA LINK statement is given for the same link name, the later statement takes precedence and earlier data are replaced. No message is printed.
  7. Notice that notes 1) through 6) above make the order in which related DATA LINK statements are given very important; related DATA LINK statements might not produce the same result if given in different orders.
  8. The dimensions for all xi,yi,zi numeric data in a DATA LINK statement are length units measured in the global coordinate system.
  9. Care should be taken in supplying accurate dimensional data since any errors result in improper shapes for the links and remain throughout the simulation. Slight errors cause inaccurate answers, while gross errors may cause completely unpredictable results.
  10. The xi,yi,zi groups of numeric data must correspond to the rules for the placement of the local joint coordinate systems (refer to the statement defining each particular type of joint). If errors are detected, the corresponding DATA LINK statement is ignored and a message is printed. Certain types of errors may not be detected until an EXECUTE or EXECUTE HOLD statement is given; these cause the simulation to be halted and a message to be printed at that time.
  11. The three points for which xi,yi,zi numeric data are given need not be unit distances apart; the local coordinate axes are normalized by IMP to form unit vectors. The points should not be chosen coincident or too close together, however; larger distances achieve more accurate placement of axes.
  12. The angle formed by points 2,1,3 need not be a right angle. IMP uses the first point to locate the local origin and uses the second point to define the direction of the local w or z axis; the local u or x axis is then taken in the half-plane defined by the local w or z axis and the third point. Any necessary adjustments are made to the third point to produce a local coordinate system with exact right angles.
  13. If the xi,yi,zi numeric data are not given for the third point, the coordinates of the global origin are used. This may be a convenient shortcut if the user is not concerned about the particular placement of the local u or x axis. In view of notes 11) and 12) above, this does not produce an error unless the local w or z axis passes through the global origin.
  14. Any of the xi,yi,zi groups of numeric data may be replaced by the alphanumeric name of a previously defined point for which a valid DATA POINT statement has previously been given (see above example).


The DATA RIGID Statement

The DATA RIGID statement simultaneously specifies the numeric data which locate the two local coordinate systems attached to the two links on either side of a RIGID joint relative to the absolute (global) frame of reference for the system.

The DATA RIGID statements, taken together with the DATA statements for other types of joints and the DATA LINK statements, describe the relative locations of the various links and joints of the system at the initial (design) position.

The initial locations of the two local coordinate systems attached to the two links joined by a RIGID statement are coincident and are both defined by a single DATA RIGID statement by specifying the global coordinates of three points (see figure). The first point defines the common origins of the two local coordinate systems. The second point lies on the common local w and w axes and the third point lies on the common local u and u axes of the coordinate systems attached to the two links joined.

Format

DATA RIGID (joint name) = x1,y1,z1; x2,y2,z2; x3,y3,z3

where joint name is the alphanumeric name of the RIGID joint connecting the two links to which the local coordinate systems are attached. The xi,yi,zi groups are numeric values for the global coordinates of the three points defining the initial locations of the two local coordinate systems.

Example

DATA RIGID (WELD) = -1.0,2.5,0.0; -1.0,3.5,0.0; -2.0,2.5,1.0

specifies the initial locations of the two coincident local coordinate systems attached to the two links connected by a RIGID joint named WELD. The above example might also take any of the following forms:

DATA RIGID (WELD) = -1,2.5,0; -1,3.5,0; -2,2.5,1
DATA RIGID (WELD) = -1,2.5, ; -1,3.5, ; -2,2.5,1
DATA RIGID (WELD) = PT1; PT2; -2,2.5,1
DATA RIGID (WELD) = PT1; PT2

Notes

  1. The joint name specified must have been defined by a previous RIGID statement. If not, the DATA RIGID statement is ignored and a message is printed.
  2. If a DATA RIGID statement or the two equivalent DATA LINK statements are not specified for each joint name defined by a RIGID statement before an EXECUTE or EXECUTE HOLD statement is given, the local coordinate system(s) with missing data is (are) initially placed coincident with the link frame of reference.
  3. If more than one DATA RIGID statement is given for the same joint name, the later statement takes precedence and earlier data are replaced.
  4. The dimensions for all xi,yi,zi numeric data in a DATA RIGID statement are length units.
  5. Care should be taken in supplying accurate dimensional data since any errors result in improper shapes for the links and remain throughout the simulation. Slight errors cause inaccurate answers, while gross errors may cause completely unpredictable results.
  6. The xi,yi,zi numeric data must define two coincident local coordinate systems (see RIGID statement).
  7. The three points for which xi,yi,zi numeric data are given need not be unit distances apart; the local u,v,w and u,v,w axes are normalized by IMP to form unit vectors. The points should not be chosen coincident or too close together, however; larger distances achieve more accurate placement of axes.
  8. The angle formed by points 2,1,3 need not be a right angle. IMP uses the first and second point to locate the common local origins and the common local w and w axes; the common local u and u axes are then formed in the half-plane defined by the common local w and w axes and the third point. A right angle is formed for the common local u and u axes in this half-plane even though this direction may not pass through the third point given.
  9. If the x3,y3,z3 data are not given for the third point, the coordinates of the global origin are used. This may be a convenient shortcut if the user is not concerned with the u,u axis placement (see final example above). In view of note 8) above, this does not produce an error unless the common local w,w axes pass through the global origin.
  10. Any of the xi,yi,zi groups of numeric data may be replaced by the alphanumeric name of a previously defined point for which a valid DATA POINT statement has previously been given (see above examples).


The DATA XPIN Statement

The DATA XPIN statement specifies the numeric data which simultaneously locate the two local coordinate systems attached to the two links on either side of an XPIN joint relative to the absolute (global) frame of reference for the system. The pin axis is initially aligned parallel to the global X axis.

The DATA XPIN statements, taken together with the DATA statements for other types of joints and the DATA LINK statements, describe the relative locations of the various links of the system at the initial (design) position.

The initial locations of the two local coordinate systems attached to the two links joined by an XPIN statement are both defined by a single DATA XPIN statement by specifying the global coordinates of three points (see figure). The first point must lie at the common origins of the two local coordinate systems. The second and third points are optional but, if given, should lie on the local positive v and v axes of the coordinate systems attached to the first and second links named in the XPIN statement, respectively.

Format

DATA XPIN (joint name) = x1,y1,z1; x2,y2,z2; x3,y3,z3

where joint name is the alphanumeric name of the XPIN joint connecting the two links to which the local u,v,w and u,v,w coordinate systems are attached. The xi,yi,zi groups are numeric values for the global coordinates of the three points defining the initial locations of the two local coordinate systems.

Examples

DATA XPIN (PIN) = -2.0,2.5,0.0; -2.0,3.5,0.0; -2.0,2.5,1.0

specifies the initial locations of the local coordinate systems attached to the two links on either side of an XPIN joint named PIN. The numeric data corresponds approximately to the figure. The above example might also take any of the following forms:

DATA XPIN (PIN) = -2,2.5,0; -2,3.5,0; -2,2.5,1
DATA XPIN (PIN) = -2,2.5, ; -2,3.5, ; -2,2.5,1
DATA XPIN (PIN) = PT1; -2,3.5,0; -2,2.5,1
DATA XPIN (PIN) = PT1

Notes

  1. The joint name specified must have been defined by a previous XPIN statement. If not, the DATA XPIN statement is ignored and a message is printed.
  2. If a DATA XPIN statement or the two equivalent DATA LINK statements are not specified for each joint name defined by an XPIN statement before an EXECUTE or EXECUTE HOLD statement is given, the local coordinate system(s) with missing data is (are) initially placed coincident with the link frame of reference.
  3. If more than one DATA XPIN statement is given for the same joint name, the later statement takes precedence and earlier data are replaced.
  4. The dimensions for all xi,yi,zi numeric data in a DATA XPIN statement are length units.
  5. Care should be taken in supplying accurate dimensional data since any errors result in improper shapes for the links and remain throughout the simulation. Slight errors cause inaccurate answers, while gross errors may cause completely unpredictable results.
  6. The xi,yi,zi numeric data must conform to the rules for the placement of the local coordinate systems for an XPIN joint (see XPIN statement). If errors are detected, the DATA XPIN statement is ignored and a message is printed. Certain types of errors may not be detected until an EXECUTE or EXECUTE HOLD statement is given; these cause the simulation to be halted and a message to be printed at that time.
  7. The three points for which xi,yi,zi numeric data are given need not be unit distances apart; the local u,v,w and u,v,w axes are normalized by IMP to form unit vectors. The points should not be chosen coincident or too close together, however (except, perhaps, for the second and third points); larger distances achieve more accurate placement of axes.
  8. The angles formed by points 2,1,3 need not lie in a plane perpendicular to the global X axis. IMP uses the first point to locate the common local origins and the common local u,u axes; the local v and v axes are then taken in the half-planes defined by the common local u,u axes and the second and third points, respectively. Right angles are formed for the local v and v axes in these half-planes even though they may not pass precisely through the second and third points, respectively.
  9. If the xi,yi,zi numeric data are not given for the second and/or third points, the local coordinate systems are placed parallel to those of the global system. This may be a convenient shortcut (see final example above), if the user is not concerned about the particular placement of the two local v and/or v axes.
  10. Any of the xi,yi,zi groups of numeric data may be replaced by the alphanumeric name of a previously defined point for which a valid DATA POINT statement has previously been given (see above examples).


The DATA YPIN Statement

The DATA YPIN statement specifies the numeric data which simultaneously locate the two local u,v,w and u,v,w coordinate systems attached to the two links on either side of a YPIN joint relative to the absolute (global) frame of reference for the system. The pin axis is initially aligned parallel to the global Y axis.

The DATA YPIN statements, taken together with the DATA statements for other types of joints and the DATA LINK statements, describe the relative locations of the various links of the system at the initial (design) position.

The initial locations of the two local coordinate systems attached to the two links joined by a YPIN statement are both defined by a single DATA YPIN statement by specifying the global coordinates of three points (see figure). The first point must lie at the common origins of the two local u,v,w and u,v,w coordinate systems. The second and third points are optional but, if given, must lie on the local positive w and w axes of the coordinate systems attached to the first and second links named in the YPIN statement, respectively.

Format

DATA YPIN (joint name) = x1,y1,z1; x2,y2,z2; x3,y3,z3

where joint name is the alphanumeric name of the YPIN joint connecting the two links to which the local u,v,w and u,v,w coordinate systems are attached. The xi,yi,zi groups are numeric values for the global coordinates of the three points defining the initial locations of the two local coordinate systems.

Examples

DATA YPIN (PIN) = -2.0,2.5,0.0; 0.0,2.5,0.5; -3.0,2.5,1.0

specifies the initial locations of the local coordinate systems attached to the two links on either side of a YPIN joint named PIN. The numeric data corresponds approximately to the figure. The above example might also take any of the following forms:

DATA YPIN (PIN) = -2,2.5,0; 0,2.5,.5; -3,2.5,1
DATA YPIN (PIN) = -2,2.5, ; ,2.5,.5; -3,2.5,1
DATA YPIN (PIN) = PT1; ,2.5,.5; -3,2.5,1
DATA YPIN (PIN) = PT1

Notes

  1. The joint name specified must have been defined by a previous YPIN statement. If not, the DATA YPIN statement is ignored and a message is printed.
  2. If a DATA YPIN statement or the two equivalent DATA LINK statements are not specified for each joint name defined by a YPIN statement before an EXECUTE or EXECUTE HOLD statement is given, the local coordinate system(s) with missing data is (are) initially placed coincident with the link frame of reference.
  3. If more than one DATA YPIN statement is given for the same joint name, the later statement takes precedence and earlier data are replaced.
  4. The dimensions for all xi,yi,zi numeric data in a DATA YPIN statement are length units.
  5. Care should be taken in supplying accurate dimensional data since any errors result in improper shapes for the links and remain throughout the simulation. Slight errors cause inaccurate answers, while gross errors may cause completely unpredictable results.
  6. The xi,yi,zi numeric data must conform to the rules for the placement of the local coordinate systems for a YPIN joint (see YPIN statement). If errors are detected, the DATA YPIN statement is ignored and a message is printed. Certain types of errors may not be detected until an EXECUTE or EXECUTE HOLD statement is given; these cause the simulation to be halted and a message to be printed at that time.
  7. The three points for which xi,yi,zi numeric data are given need not be unit distances apart; the local u,v,w and u,v,w axes are normalized by IMP to form unit vectors. The points should not be chosen coincident or too close together, however (except, perhaps, for the second and third points); larger distances achieve more accurate placement of axes.
  8. The angles formed by points 2,1,3 need not lie in a plane perpendicular to the global Y axis. IMP uses the first point to locate the common local origins and the common local v,v axes; the local w and w axes are then taken in the half-planes defined by the common local v,v axes and the second and third points, respectively. Right angles are formed for the local w and w axes in these half-planes even though they may not pass precisely through the second and third points, respectively.
  9. If the xi,yi,zi numeric data are not given for the second and/or third points, the local coordinate systems are placed parallel to those of the global system. This may be a convenient shortcut (see final example above), if the user is not concerned about the particular placement of the local w and w axes.
  10. Any of the xi,yi,zi groups of numeric data may be replaced by the alphanumeric name of a previously defined point for which a valid DATA POINT statement has previously been given (see above examples).

The DATA ZPIN Statement

The DATA ZPIN statement specifies the numeric data which simultaneously locate the two local coordinate systems attached to the two links on either side of a ZPIN joint relative to the absolute (global) frame of reference for the system. The pin axis is initially aligned parallel to the global Z axis.

The DATA ZPIN statement, taken together with the DATA statements for other types of joints and the DATA LINK statements, describe the relative locations of the various links of the system at the initial (design) position.

The initial locations of the two local coordinate systems attached to the two links joined by a ZPIN statement are both defined by a single DATA ZPIN statement by specifying the global coordinates of three points (see figure). The first point must lie at the common origins of the two local coordinate systems. The second and third points must lie on the local positive u and u axes of the coordinate systems attached to the first and second links named in the ZPIN statement.

Format

DATA ZPIN (joint name) = x1,y1,z1; x2,y2,z2; x3,y3,z3

where joint name is the alphanumeric name of the ZPIN joint connecting the two links to which the local coordinate systems are attached. The xi,yi,zi groups are numeric values for the global coordinates of the three points defining the initial locations of the two local coordinate systems.

Examples

DATA ZPIN (PIN) = -2.0,2.5,0.0; -2.0,3.5,0.0; 0.0,2.5,0.5

specifies the initial locations of the local coordinate systems attached to the two links on either side of a ZPIN joint named PIN. The numeric data corresponds approximately to the figure. The above example might also take any of the following forms:

DATA ZPIN (PIN) = -2,2.5,0; -2,3.5,0; 0,2.5,.5
DATA ZPIN (PIN) = -2,2.5, ; -2,3.5, ; ,2.5,.5
DATA ZPIN (PIN) = PT1; PT2; 0,2.5,.5
DATA ZPIN (PIN) = PT1

Notes

  1. The joint name specified must have been defined by a previous ZPIN statement. If not, the DATA ZPIN statement is ignored and a message is printed.
  2. If a DATA ZPIN statement or the two equivalent DATA LINK statements are not specified for each joint name defined by a ZPIN statement before an EXECUTE or EXECUTE HOLD statement is given, the local coordinate system(s) with missing data is (are) initially placed coincident with the link frame of reference.
  3. If more than one DATA ZPIN statement is given for the same joint name, the later statement takes precedence and earlier data are replaced.
  4. The dimensions for all xi,yi,zi numeric data in a DATA ZPIN statement are length units.
  5. Care should be taken in supplying accurate dimensional data since any errors result in improper shapes for the links and remain throughout the simulation. Slight errors cause inaccurate answers, while gross errors may cause completely unpredictable results.
  6. The xi,yi,zi numeric data must conform to the rules for the placement of the local coordinate systems for a ZPIN joint (see ZPIN statement). If errors are detected, the DATA ZPIN statement is ignored and a message is printed. Certain types of errors may not be detected until an EXECUTE or EXECUTE HOLD statement is given; these cause the simulation to be halted and a message to be printed at that time.
  7. The three points for which xi,yi,zi numeric data are given need not be unit distances apart; the local u,v,w and u,v,w axes are normalized by IMP to form unit vectors. The points should not be chosen coincident or too close together, however (except, perhaps, for the second and third points); larger distances achieve more accurate placement of axes.
  8. The angles formed by points 2,1,3 need not lie in a plane perpendicular to the global Z axis. IMP uses the first point to locate the common local origins and the common local w,w axes; the local u and u axes are then taken in the half-planes defined by the common local w,w axes and the second and third points, respectively. Right angles are formed for the local u and u axes in these half-planes even though they may not pass precisely through the second and third points, respectively.
  9. If the xi,yi,zi numeric data are not given for the second and/or third points, the local coordinate systems are placed parallel to those of the global system. This may be a convenient shortcut (see final example above), if the user is not concerned about the particular placement of the two local u and u axes.
  10. Any of the xi,yi,zi groups of numeric data may be replaced by the alphanumeric name of a previously defined point for which a valid DATA POINT statement has previously been given (see above examples).

The DATA REVOLUTE Statement

The DATA REVOLUTE statement specifies the numeric data which simultaneously locate the two local coordinate systems attached to the two links on either side of a REVOLUTE joint relative to the absolute (global) frame of reference for the system.

The DATA REVOLUTE statements, taken together with the DATA statements for other types of joints and the DATA LINK statements, describe the relative locations of the various links of the system at the initial (design) position.

The initial locations of the two local coordinate systems attached to the two links joined by a REVOLUTE statement are both defined by a single DATA REVOLUTE statement by specifying the global coordinates of four points (see figure). The first point must lie at the common origins of the two local coordinate systems and the second point must lie on the common local positive w,w axes. The third and fourth points must lie on the local positive u and u axes of the coordinate systems attached to the first and second links named in the REVOLUTE statement, respectively.

Format

DATA REVOLUTE (joint name) = x1,y1,z1; x2,y2,z2; x3,y3,z3; x4,y4,z4

where joint name is the alphanumeric name of the REVOLUTE joint connecting the two links to which the local coordinate systems are attached. The xi,yi,zi groups are numeric values for the global coordinates of the four points defining the initial locations of the two local coordinate systems.

Examples

DATA REVOLUTE (PIN) = -2.0,2.5,0.0; -2.0,3.5,0.0; $
  0.0,2.5,0.5; -3.0,2.5,1.0

specifies the initial locations of the local coordinate systems attached to the two links on either side of a REVOLUTE joint named PIN. The numeric data corresponds approximately to the figure. The above example might also take any of the following forms:

DATA REVOLUTE (PIN) = -2,2.5,0; -2,3.5,0; 0,2.5,.5; -3,2.5,1
DATA REVOLUTE (PIN) = -2,2.5, ; -2,3.5, ; ,2.5,.5; -3,2.5,1
DATA REVOLUTE (PIN) = PT1; PT2; 0,2.5,.5; -3,2.5,1
DATA REVOLUTE (PIN) = PT1; PT2

Notes

  1. The joint name specified must have been defined by a previous REVOLUTE statement. If not the DATA REVOLUTE statement is ignored and a message is printed.
  2. If a DATA REVOLUTE statement or the two equivalent DATA LINK statements are not specified for each joint name defined by a REVOLUTE statement before an EXECUTE or EXECUTE HOLD statement is given, the local coordinate system(s) with missing data is (are) initially placed coincident with the link frame of reference.
  3. If more than one DATA REVOLUTE statement is given for the same joint name, the later statement takes precedence and earlier data are replaced.
  4. The dimensions for all xi,yi,zi numeric data in a DATA REVOLUTE statement are length units.
  5. Care should be taken in supplying accurate dimensional data since any errors result in improper shapes for the links and remain throughout the simulation. Slight errors cause inaccurate answers, while gross errors may cause completely unpredictable results.
  6. The xi,yi,zi numeric data must conform to the rules for the placement of the local coordinate systems for a revolute joint (see REVOLUTE statement). If errors are detected, the DATA REVOLUTE statement is ignored and a message is printed. Certain types of errors may not be detected until an EXECUTE or EXECUTE HOLD statement is given; these cause the simulation to be halted and a message to be printed at that time.
  7. The four points for which xi,yi,zi numeric data are given need not be unit distances apart; the local u,v,w and u,v,w axes are normalized by IMP to form unit vectors. The points should not be chosen coincident or too close together, however (except, perhaps, for the third and fourth points); larger distances achieve more accurate placement of axes.
  8. The angles formed by points 2,1,3 and by points 2,1,4 need not be right angles. IMP uses the first and second points to locate the common local origins and the common local w,w axes; the local u and u axes are then taken in the half-planes defined by the common local w,w axes and the third and fourth points, respectively. Right angles are formed for the local u and u axes in these half-planes even though they may not pass through the third and fourth points, respectively.
  9. If the xi,yi,zi numeric data are not given for the third and/or fourth points, the coordinates of the global origin are used. In view of note 8) above, this does not produce an error unless the pin axis passes through the global origin. This may be a convenient shortcut (see final example above), if the user is not concerned about the particular placement of the local u and u axes.
  10. Any of the xi,yi,zi groups of numeric data may be replaced by the alphanumeric name of a previously defined point for which a valid DATA POINT statement has previously been given (see above examples).

The DATA XSLIDE Statement

The DATA XSLIDE statement specifies the numeric data which simultaneously locates the two local coordinate systems attached to the two links on either side of an XSLIDE joint relative to the absolute (global) frame of reference for the system. The sliding axis is initially aligned parallel to the global X axis.

The DATA XSLIDE statements, taken together with the DATA statements for other types of joints and the DATA LINK statements, describe the relative locations of the various links of the system at the initial (design) position.

The initial locations of the two local coordinate systems attached to the two links joined by an XSLIDE statement are coincident and are both defined by a single DATA XSLIDE statement by specifying the global coordinates of one point (see figure). The point defines the common origins of the two local coordinate systems. The local coordinate axes attached to the two links are set parallel to the global axes.

Format

DATA XSLIDE (joint name) = x1,y1,z1

where joint name is the alphanumeric name of the XSLIDE joint connecting the two links to which the local coordinate systems are attached. The x1,y1,z1 are numeric values for the global coordinates of the point defining the initial location of the origin of the two local coordinate systems.

Examples

DATA XSLIDE (SLIP) = -1.0,1.0,1.0

specifies the initial locations of the coordinate systems attached to the two links on either side of a XSLIDE joint named SLIP. The numeric data corresponds approximately to the figure.

The above example might also take any of the following forms:

DATA XSLIDE (SLIP) = -1,1,0
DATA XSLIDE (SLIP) = -1,1
DATA XSLIDE (SLIP) = PT1

Notes

  1. The joint name specified must have been defined by a previous XSLIDE statement. If not, the DATA XSLIDE statement is ignored and a message is printed.
  2. If a DATA XSLIDE statement or the two equivalent DATA LINK statements are not specified for each joint name defined by an XSLIDE statement before an EXECUTE or EXECUTE HOLD statement is given, the local coordinate system(s) with missing data is (are) initially placed coincident with the link frame of reference.
  3. If more than one DATA XSLIDE statement is given for the same joint name the later statement takes precedence and earlier data are replaced.
  4. The dimensions for the x1,y1,z1 numeric data in a DATA XSLIDE statement are length units.
  5. Care should be taken in supplying accurate dimensional data since any errors result in improper shapes for the links and remain throughout the simulation. Slight errors cause inaccurate answers, while gross errors may cause completely unpredictable results.
  6. The x1,y1,z1 group of numeric data may be replaced by the alphanumeric name of a previously defined point for which a valid DATA POINT statement has previously been given (see last example above).

The DATA YSLIDE Statement

The DATA YSLIDE statement specifies the numeric data which simultaneously locates the two local coordinate systems attached to the two links on either side of a YSLIDE joint relative to the absolute (global) frame of reference for the system. The sliding axis is initially aligned parallel to the global Y axis.

The DATA YSLIDE statements, taken together with the DATA statements for other types of joints and the DATA LINK statements, describe the relative locations of the various links of the system at the initial (design) position.

The initial locations of the two local coordinate systems attached to the two links joined by a YSLIDE statement are coincident and are both defined by a single DATA YSLIDE statement by specifying the global coordinates of one point (see figure). The point defines the common origins of the two local coordinate systems. The local coordinate axes attached to the two links are set parallel to the global axes.

Format

DATA YSLIDE (joint name) = x1,y1,z1

where joint name is the alphanumeric name of the YSLIDE joint connecting the two links to which the local coordinate systems are attached. The x1,y1,z1 are numeric values for the global coordinates of the point defining the initial location of the origin of the two local coordinate systems.

Examples

DATA YSLIDE (SLIP) = -1.0,1.0,1.0

specifies the initial locations of the coordinate systems attached to the two links on either side of a YSLIDE joint named SLIP. The numeric data corresponds approximately to the figure.

The above example might also take any of the following forms:

DATA YSLIDE (SLIP) = -1,1,0
DATA YSLIDE (SLIP) = -1,1
DATA YSLIDE (SLIP) = PT1

Notes

  1. The joint name specified must have been defined by a previous YSLIDE statement. If not, the DATA YSLIDE statement is ignored and a message is printed.
  2. If a DATA YSLIDE statement or the two equivalent DATA LINK statements are not specified for each joint name defined by a YSLIDE statement before an EXECUTE or EXECUTE HOLD statement is given, the local coordinate system(s) with missing data is (are) initially placed coincident with the link frame of reference.
  3. If more than one DATA YSLIDE statement is given for the same joint name the later statement takes precedence and earlier data are replaced.
  4. The dimensions for the x1,y1,z1 numeric data in a DATA YSLIDE statement are length units.
  5. Care should be taken in supplying accurate dimensional data since any errors result in improper shapes for the links and remain throughout the simulation. Slight errors cause inaccurate answers, while gross errors may cause completely unpredictable results.
  6. The x1,y1,z1 group of numeric data may be replaced by the alphanumeric name of a previously defined point for which a valid DATA POINT statement has previously been given (see last example above).

The DATA ZSLIDE Statement

The DATA ZSLIDE statement specifies the numeric data which simultaneously locates the two local coordinate systems attached to the two links on either side of a ZSLIDE joint relative to the absolute (global) frame of reference for the system. The sliding axis is aligned parallel to the global Z axis.

The DATA ZSLIDE statements, taken together with the DATA statements for other types of joints and the DATA LINK statements, describe the relative locations of the various links of the system at the initial (design) position.

The initial locations of the two local coordinate systems attached to the two links joined by a ZSLIDE statement are coincident and are both defined by a single DATA ZSLIDE statement by specifying the global coordinates of one point (see figure). The point defines the common origins of the two local coordinate systems. The local coordinate axes attached to the two links are set parallel to the global axes.

Format

DATA ZSLIDE (joint name) = x1,y1,z1

where joint name is the alphanumeric name of the ZSLIDE joint connecting the two links to which the local coordinate systems are attached. The x1,y1,z1 are numeric values for the global coordinates of the point defining the initial location of the origin of the two local coordinate systems.

Examples

DATA ZSLIDE (SLIP) = -1.0,1.0,1.0

specifies the initial locations of the coordinate systems attached to the two links on either side of a ZSLIDE joint named SLIP. The numeric data corresponds approximately to the figure.

The above example might also take any of the following forms:

DATA ZSLIDE (SLIP) = -1,1,0
DATA ZSLIDE (SLIP) = -1,1
DATA ZSLIDE (SLIP) = PT1

Notes

  1. The joint name specified must have been defined by a previous ZSLIDE statement. If not, the DATA ZSLIDE statement is ignored and a message is printed.
  2. If a DATA ZSLIDE statement or the two equivalent DATA LINK statements are not specified for each joint name defined by a ZSLIDE statement before an EXECUTE or EXECUTE HOLD statement is given, the local coordinate system(s) with missing data is (are) initially placed coincident with the link frame of reference.
  3. If more than one DATA ZSLIDE statement is given for the same joint name the later statement takes precedence and earlier data are replaced.
  4. The dimensions for the x1,y1,z1 numeric data in a DATA ZSLIDE statement are length units.
  5. Care should be taken in supplying accurate dimensional data since any errors result in improper shapes for the links and remain throughout the simulation. Slight errors cause inaccurate answers, while gross errors may cause completely unpredictable results.
  6. The x1,y1,z1 group of numeric data may be replaced by the alphanumeric name of a previously defined point for which a valid DATA POINT statement has been previously given (see last example above).

The DATA PRISM Statement

The DATA PRISM statement specifies the numeric data which simultaneously locates the two local coordinate systems attached to the two links on either side of a prismatic joint relative to the absolute (global) frame of reference for the system.

The DATA PRISM statements, taken together with the DATA statements for other types of joints and the DATA LINK statements, describe the relative locations of the various links of the system at the initial (design) position.

The initial locations of the two local coordinate systems attached to the two links joined by a PRISM statement are coincident and are both defined by a single DATA PRISM statement by specifying the global coordinates of three points (see figure). The first point defines the common origins of the two local coordinate systems. The second point must be located on the common local positive w,w axes. The third point must lie in the half-plane defined by the common local w,w axes and the common local positive u,u axes.

Format

DATA PRISM (joint name) = x1,y1,z1; x2,y2,z2; x3,y3,z3

where joint name is the alphanumeric name of the PRISM joint connecting the two links to which the local coordinate systems are attached. The xi,yi,zi groups are numeric values for the global coordinates of the three points defining the initial locations of the two local coordinate systems.

Examples

DATA PRISM (SLIP)= -1.0,1.0,0.0; -1.0,4.0,0.0; 0.0,1.0,-0.5

specifies the initial locations of the coordinate systems attached to the two links on either side of a PRISM joint named SLIP. The numeric data correspond approximately to the figure.

The above example might also take any of the following forms:

DATA PRISM (SLIP) = -1,1,0; -1,4,0; 0,1,-.5
DATA PRISM (SLIP) = -1,1, ; -1,4, ; ,1,-.5
DATA PRISM (SLIP) = PT1; PT2; 0,1,-.5
DATA PRISM (SLIP) = PT1; PT2

Notes

  1. The joint name specified must have been defined by a previous PRISM statement. If not, the DATA PRISM statement is ignored and a message is printed.
  2. If a DATA PRISM statement or the two equivalent DATA LINK statements are not specified for each joint name defined by a PRISM statement before an EXECUTE or EXECUTE HOLD statement is given, the local coordinate system(s) with missing data is (are) initially placed coincident with the link frame of reference.
  3. If more than one DATA PRISM statement is given for the same joint name the later statement takes precedence and earlier data are replaced.
  4. The dimensions for all xi,yi,zi numeric data in a DATA PRISM statement are length units.
  5. Care should be taken in supplying accurate dimensional data since any errors result in improper shapes for the links and remain throughout the simulation. Slight errors cause inaccurate answers, while gross errors may cause completely unpredictable results.
  6. The xi,yi,zi numeric data must conform to the rules for the placement of the local coordinate systems for a PRISM joint (see PRISM statement). If errors are detected, the DATA PRISM statement is ignored and a message is printed. Certain types of errors may not be detected until an EXECUTE or EXECUTE HOLD statement is given; these cause the simulation to be halted and a message to be printed at that time.
  7. The three points for which xi,yi,zi numeric data are given need not be unit distances apart; the local u,v,w and u,v,w axes are normalized by IMP to form unit vectors. The points should not be chosen coincident or too close together, however; larger distances achieve more accurate placement of axes.
  8. The angle formed by points 2,1,3 need not be a right angle. IMP uses the first point to locate the common local origins extending vectors from there toward the second point; it forms the common local w,w axes. The common local positive u,u axes are taken in the half-plane defined by the common local w,w axes and the third point; a right angle is then formed for the common local u,u axes in the half-plane even though they may not pass through the third point.
  9. If the x3,y3,z3 numeric data are not given for the third point, the coordinates of the global origin are used. In view of note 8) above, this does not produce an error unless the common local w,w axes pass through the global origin. This may be a convenient shortcut (see final example above) if the user is not concerned about the particular placement of the local u and u axes.
  10. Any of the xi,yi,zi groups of numeric data may be replaced by the alphanumeric name of a previously defined point for which a valid DATA POINT statement has previously been given (see last example above).

The DATA GEAR Statement

The DATA GEAR statement specifies the gear ratio and the center to center distance for a GEAR joint.

Format

DATA GEAR (joint name) = ratio, distance

where joint name is the alphanumeric name of the GEAR joint, ratio is the numeric value of the gear ratio for the joint, and distance is the numeric value of the center to center distance (the sum of the pitch radii) for the two mating GEAR sectors.

Example

DATA GEAR (SPUR) = 2.625, 6.25

specifies that the gear ratio of a spur gear joint named SPUR is 84:32 = 2.625, and that the sum of the pitch radii of the mating gear sectors is 4.526 + 1.724 = 6.25 length units.

Notes

  1. There must be a DATA GEAR statement for each joint defined by a GEAR statement. If these are not specified before an EXECUTE or EXECUTE HOLD statement is given, the simulation is halted and a message is printed.
  2. The joint name specified must have been defined by a previous GEAR statement. If not, the DATA GEAR statement is ignored and a message is printed.
  3. Unlike DATA statements describing certain other types of joints (for example, the DATA ZPIN statement), the DATA GEAR statement does not specify the locations of the two local coordinate systems for the GEAR joint; two DATA LINK statements must be defined for each joint name defined by a GEAR statement. If these do not appear before an EXECUTE or EXECUTE HOLD statement is given, the local coordinate system(s) with missing data is (are) initially placed coincident with the link frame of reference.
  4. If more than one DATA GEAR statement is given for the same joint name, the later statement takes precedence; earlier data are replaced and a message is printed.
  5. The value of ratio is dimensionless; the value of distance has units of length.
  6. The value of ratio is the ratio of the number of teeth (or the pitch diameter) of the first gear named in the GEAR statement to the number of teeth (or pitch diameter) of the second gear named. A positive value of ratio indicates that both are external gears, while a negative ratio indicates an internal-external gear combination.
  7. A value of zero may not be used for ratio to represent a gear-rack combination. A zero value for ratio causes the DATA GEAR statement to be ignored and a message to be printed.
  8. The center to center distance is optional; it need not be specified by the user. If it is not specified before an EXECUTE or EXECUTE HOLD statement is given, it will be calculated from data for the local coordinate systems on either side of the joint at that time.
  9. If the center to center distance is given, it should be consistent with the placement of the two local coordinate systems on either side of the gear joint. If not consistent at the time an EXECUTE or EXECUTE HOLD statement is given, the kinematic shapes of all links will be found first from the locations of the local coordinate systems; the two gear centers will then be set to the specified distance; any discrepancies will be compensated for by movements within the joints of the system when assembly is attempted at the design (initial) position.

The DATA BEVEL Statement

The DATA BEVEL statement specifies the gear ratio and the size of the two bevel gears defined by a previous BEVEL statement.

Format

DATA BEVEL (joint name) = ratio, radius

where each joint name is the alphanumeric name of the BEVEL joint, ratio is the numeric value of the gear ratio for the joint, and radius is the pitch circle radius of the second link named in the BEVEL statement.

Example

DATA BEVEL (BVL) = 2.625, 2.0

specifies that the gear ratio of a BEVEL joint named BVL is 84/32 = 2.625 and that the back-face pitch circle radii of the two bevel gears are 5.25 and 2.0 length units, respectively.

Notes

  1. There must be a DATA BEVEL statement for each joint defined by a BEVEL statement. If these are not specified before an EXECUTE or EXECUTE HOLD statement is given, the simulation is halted and a message is printed.
  2. The joint name specified must have been defined by a previous BEVEL statement. If not, the DATA BEVEL statement is ignored and a message is printed.
  3. Unlike DATA statements describing certain other types of joints (for example, the DATA ZPIN statement), the DATA BEVEL statement does not specify the locations of the two local coordinate systems for the BEVEL joint; two DATA LINK statements must be defined for each BEVEL joint. If these do not appear before an EXECUTE or EXECUTE HOLD statement is given, the local coordinate system(s) with missing data is (are) initially placed coincident with the link frame of reference.
  4. If more than one DATA BEVEL statement is given for the same joint name, the later statement takes precedence; earlier data are replaced and a message is printed.
  5. The value of ratio is dimensionless; the value of radius has units of length.
  6. The value of ratio is the ratio of the number of teeth of the first bevel gear named in the BEVEL statement to the number of teeth of the second.
  7. The value of ratio must be a positive number. A zero or negative value for ratio causes the DATA BEVEL statement to be ignored and a message to be printed.
  8. The angle between the two intersecting shafts of a BEVEL joint is always 90 ° . The two local coordinate systems defined by the two DATA LINK statements are assumed to be at consistent distances from the intersection of the two shafts, that is, the u,v and u’,v’ planes are both chosen to go through the point of contact of the respective pitch circles (see figure with BEVEL statement). The radius specified is the pitch circle radius of the second gear named, measured in the u,v plane. It should equal the distance from the shaft intersection to the u,v plane.


The DATA RACK Statement

The DATA RACK statement specifies the pinion radius for a RACK joint.

Format

DATA RACK (joint name) = radius

where each joint name is the alphanumeric name of the RACK joint and radius is the pitch circle radius of the second link named in the RACK statement.

Example

DATA RACK (MESH) = 2.5

specifies that the pitch circle radius of the pinion in a RACK joint named MESH is 2.5 length units.

Notes

  1. There must be a DATA RACK statement for each joint defined by a RACK statement. If these are not specified before an EXECUTE or EXECUTE HOLD statement is given, the simulation is halted and a message is printed.
  2. The joint name specified must have been defined by a previous RACK statement. If not, the DATA RACK statement is ignored and a message is printed.
  3. Unlike DATA statements describing certain other types of joints (for example, the DATA ZPIN statement), the DATA RACK statement does not specify the locations of the two local coordinate systems for the RACK joint; two DATA LINK state- ments must also be defined for each RACK joint. If these do not appear before an EXECUTE or EXECUTE HOLD statement is given, the local u,v,w or u,v,w coordinate system(s) with missing data is (are) initially placed coincident with the x,y,z link frame of reference.
  4. If more than one DATA RACK statement is given for the same joint name, the later statement takes precedence; earlier data are replaced and a message is printed.
  5. The value of radius has units of length. It should be equal to the perpendicular distance from the local u,v,w origin to the local u axis (see figure with the RACK statement).
  6. The value of radius may not be zero. If zero is specified for radius, the DATA RACK statement is ignored and a message is printed.


The DATA SCREW Statement

The DATA SCREW statement specifies the lead of a screw joint.

Format

DATA SCREW (joint name) = value

where joint name is the alphanumeric name of the SCREW joint and value is the numeric value of the lead of the SCREW joint thread.

Example

DATA SCREW (THRD) = -0.750

specifies the lead of a SCREW joint named THRD as 0.750 length units per revolution with a left-hand thread.

Notes

  1. There must be a DATA SCREW statement for each joint defined by a SCREW statement. If these are not specified before an EXECUTE or EXECUTE HOLD statement is given, the simulation is halted and a message is printed.
  2. The joint name specified must have been defined by a previous SCREW statement. If not, the DATA SCREW statement is ignored and a message is printed.
  3. Unlike DATA statements describing certain other types of joints (for example, the DATA ZPIN statement), the DATA SCREW statement does not specify the locations of the two local coordinate systems for the SCREW joint; two DATA LINK statements must also be specified for each joint name defined by a SCREW statement. If these do not appear before an EXECUTE or EXECUTE HOLD statement is given, the local coordinate system(s) with missing data is (are) initially placed coincident with the link frame of reference.
  4. If more than one DATA SCREW statement is given for the same joint name, the later statement takes precedence; earlier data are replaced and a message is printed.
  5. The dimensions of value are length units of advance of the screw per revolution. A right-hand thread has a positive value and a left-hand thread has a negative value.
  6. The value of the lead may not be zero. A REVOLUTE statement should be used instead of a SCREW for this case. If zero is specified for value, the DATA SCREW statement is ignored and a message is printed.


The DATA CAM Statement

The DATA CAM statement specifies the shape of the pitch curve for a CAM joint.

Format

DATA CAM (joint name) = value name

where joint name is the alphanumeric name of the CAM joint and value name is the alphanumeric name of a previously defined VALUE expression set equal to a TABLE function giving data for the pitch curve for the CAM joint.

Example

VALUE (R) = TABLE (PHI): datafile.dat
DATA CAM (CURV) = R

specifies that the pitch curve radius of a CAM joint named CURV is specified by a VALUE expression named R which refers to a TABLE function referencing a file named “datafile.dat.

Notes

  1. There must be a DATA CAM statement for each joint defined by a CAM statement. If these are not specified before an EXECUTE or EXECUTE HOLD statement is given, the simulation is halted and a message is printed.
  2. The joint name specified must have been defined by a previous CAM statement. If not, the DATA CAM statement is ignored and a message is printed.
  3. Unlike DATA statements describing certain other types of joints (for example, the DATA ZPIN statement), the DATA CAM statement does not specify the locations of the two local coordinate systems for the CAM joint; two DATA LINK state- ments must also be defined for each CAM joint. If these do not appear before an EXECUTE or EXECUTE HOLD statement is given, the local coordinate system(s) with missing data is (are) initially placed coincident with the link frame of reference.
  4. If more than one DATA CAM statement is given for the same joint name, the later statement takes precedence; earlier data are replaced and a message is printed.
  5. The value name must refer to a previously defined VALUE expression consisting solely of a TABLE function; other kinds of VALUE expression cannot be used. If this is not satisfied the DATA CAM statement is ignored and a message is printed.
  6. The argument of the TABLE function is arbitrary and is not used. During the simulation, the TABLE function is evaluated as if the independent variable is the first joint variable of the CAM joint, an angle (in radians). Thus the data file referred to by the TABLE function should specify tabular data (see section 2-7.29) for the radius of the pitch curve as a function of angle (in radians) measured relative to the u,v coordinate system (see figure with the CAM statement) of the first link named in the CAM statement. The tabular data should specify radii for equally spaced angular increments for a full rotation (2 PI = 6.28318 radians).
  7. The dimensions of the tabular data for the pitch curve radius are in length units.


The DATA SLOT Statement

The DATA SLOT statement specifies the shape of the slot for a SLOT joint.

Format

DATA SLOT (joint name) = value name

where joint name is the alphanumeric name of the SLOT joint and value name is the alphanumeric name of a previously defined VALUE expression set equal to a TABLE function giving data for the centerline curve of the slot.

Example

VALUE (Y) = TABLE (PHI`): datafile.dat
DATA SLOT (CURV) = V

specifies that the profiled shape of the centerline curve of a SLOT joint named CURV is specified by a file named “datafile.dat and a VALUE expression named V accessing that file via a TABLE function.

Notes

  1. There must be a DATA SLOT statement for each joint defined by a SLOT statement. If these are not specified before an EXECUTE or EXECUTE HOLD statement is given, the simulation is halted and a message is printed.
  2. The joint name specified must have been defined by a previous SLOT statement. If not, the DATA SLOT statement is ignored and a message is printed.
  3. Unlike DATA statements describing certain other types of joints (for example, the DATA ZPIN statement), the DATA SLOT statement does not specify the locations of the two local coordinate systems for the SLOT joint; two DATA LINK statements must also be defined for each SLOT joint. If these do not appear before an EXECUTE or EXECUTE HOLD statement is given, the local coordinate system(s) with missing data is (are) initially placed coincident with the link frame of reference.
  4. If more than one DATA SLOT statement is given for the same joint name, the later statement takes precedence; earlier data are replaced and a message is printed.
  5. The value name must refer to a previously defined VALUE expression consisting solely of a TABLE function; other kinds of VALUE expression cannot be used. If this is not satisfied the DATA SLOT statement is ignored and a message is printed.
  6. The argument of the TABLE function is arbitrary and is not used. During the simulation, the TABLE function is evaluated as if the independent variable is the first joint variable of the SLOT joint, a distance along the u axis (see figure for the SLOT joint). Thus the datafile referred to by the TABLE function should specify tabular data (see section 2-7.29) for the v distances for the profiled slot centerline as a function of u relative to the u,v coordinate system of the first link named in the SLOT statement. The tabular data should specify v(u) values for equally spaced increment of u over the full length of the slot.
  7. The dimensions for v in the tabular data for the slot profile are length units.


The DATA CYLINDER Statement

The DATA CYLINDER statement specifies the numeric data which simultaneously locates the two local coordinate systems attachedto the two links on either side of a CYLINDER joint relative tothe absolute (global) frame of reference for the system.

The DATA CYLINDER statements, taken together with the DATA statements for other types of joints and the DATA LINK statements,describe the relative locations of the various links of the systemat the initial (design) position.

The initial locations of the two local coordinate systems attached to the two links joined by a CYLINDER statement are coincident and are both defined by a single DATA CYLINDER statement by specifying the global coordinates of three points (see figure). The first point must lie at the common origin of the two localcoordinate systems. The second point must be located on the common local positive w,w axes. The third point must lie in the half-plane defined by the common local w,w axes and the common local positive u,u axes.

Format

DATA CYLINDER (joint name) = x1,y1,z1; x2,y2,z2; x3,y3,z3

where joint name is the alphanumeric name of the CYLINDER joint connecting the two links to which the local coordinate systems are attached. The xi,yi,zi groups are numeric values for the global coordinates of the three points defining the initial locations of the two local u,v,w and u,v,w coordinate systems.

Examples

DATA CYLINDER(CYL)=-1.0,1.0,0.0;-1.0,4.0,0.0;0.0,1.0,-0.5

specifies the initial locations of the two coincident u,v,w and u,v,w coordinate systems attached to the two links on either side of a CYLINDER joint named CYL. The numeric data corresponds approximately to the figure.

The above example might also take any of the following forms:

DATA CYLINDER (CYL) = -1,1,0; -1,4,0; 0,1,-.5
DATA CYLINDER (CYL) = -1,1, ; -1,4, ; ,1,-.5
DATA CYLINDER (CYL) = PT1; PT2; 0,1,-.5
DATA CYLINDER (CYL) = PT1; PT2

Notes

  1. The joint name specified must have been defined by a previous CYLINDER statement. If not, the DATA CYLINDER statement is ignored and a message is printed.
  2. If a DATA CYLINDER statement or the two equivalent DATA LINK statements are not specified for each joint name defined by a CYLINDER statement before an EXECUTE or EXECUTE HOLD statement is given, the local coordinate system(s) with missing data is (are) initially placed coincident with the link frame of reference.
  3. If more than one DATA CYLINDER statement is given for the same joint name, the later statement takes precedence and earlier data are replaced.
  4. The dimensions for all xi,yi,zi numeric data in a DATA CYLINDER statement are length units.
  5. Care should be taken in supplying accurate dimensional data since any errors result in improper shapes for the links and remain throughout the simulation. Slight errors cause inaccurate answers, while gross errors may cause completely unpredictable results.
  6. The xi,yi,zi numeric data must conform to the rules for the placement of the local coordinate systems for a CYLINDER joint (see CYLINDER statement). If errors are detected, the DATA CYLINDER statement is ignored and a message is printed. Certain types of errors may not be detected until an EXECUTE or EXECUTE HOLD statement is given; these cause the simulation to be halted and a message to be printed at that time.
  7. The three points for which xi,yi,zi numeric data are given need not be unit distances apart; the local u,v,w and u,v,w axes are normalized by IMP to form unit vectors. The points should not be chosen coincident or too close together, however; larger distances achieve more accurate placement of axes.
  8. The angle formed by points 2,1,3 need not be a right angle. IMP uses the first point to locate the two coincident local origins; extending a vector toward the second point, it then forms the common local w and w axes. The common local positive u and u axes are then taken in the half-plane defined by the common local w and w axes and the third point; a right angle is formed for the common local u and u axes in this half-plane even though they may not exactly pass through the third point.
  9. If the xi,yi,zi numeric data are not given for the third point, the coordinates of the global origin are used. In view of note 8) above, this does not produce an error unless the common local w,w axes pass through the global origin. This may be a convenient shortcut (see final example above) if the user is not concerned about the particular placement of the local u and u axes.
  10. Any of the xi,yi,zi groups of numeric data may be replaced by the alphanumeric name of a previously defined point for which a valid DATA POINT statement has previously been given (see above examples).

The DATA UJOINT Statement

The DATA UJOINT statement specifies the numeric data which simultaneously locate the two local coordinate systems attached to the two links on either side of a UJOINT joint relative to the absolute (global) frame of reference for the system.

The DATA UJOINT statements, taken together with the DATA statements for other types of joints and the DATA LINK statements, describe the of relative locations the various links of the system at the initial (design) position.

The initial locations of the two local coordinate systems attached to the two links joined by a UJOINT statement are both defined by a single DATA UJOINT statement by specifying the global coordinates of three points (see figure). The first point must lie at the common origins of the two local coordinate systems. The second and third points must lie on the local positive w and w’ axes of the coordinate systems attached to the first and second links named in the UJOINT statement, respectively.

Format

DATA UJOINT (joint name) = x1,y1,z1; x2,y2,z2; x3,y3,z3

where joint name is the alphanumeric name of the UJOINT connecting the two links to which the local coordinate systems are attached. The xi,yi,zi groups are numeric values for the global coordinates of the three points defining the initial locations of the two local coordinate systems.

Examples

DATA UJOINT (UJNT) = -1.0,2.0,0.0; 0.0,2.0,1.0; -1.0,3.0,0.0

specifies the initial locations of the local coordinate systems attached to the two links on either side of a UJOINT named UJNT. The numeric data corresponds approximately to the figure.

The above example might also take any of the following forms:

DATA UJOINT (UJNT) = -1,2,0; 0,2,1; -1,3,0
DATA UJOINT (UJNT) = -1,2, ; ,2,1; -1,3
DATA UJOINT (UJNT) = PT1; 0,2,1; -1,3,0
DATA UJOINT (UJNT) = PT1; PT2; PT3

Notes

  1. The joint name specified must have been defined by a previous UJOINT statement. If not, the DATA UJOINT statement is ignored and a message is printed.
  2. If a DATA UJOINT statement or the two equivalent DATA LINK statements are not specified for each joint name defined by a UJOINT statement before an EXECUTE or EXECUTE HOLD statement is given, the local coordinate system(s) with missing data is (are) initially placed coincident with the link frame of reference.
  3. If more than one DATA UJOINT statement is given for the same joint name, the later statement takes precedence and earlier data are replaced.
  4. The dimensions for all xi,yi,zi numeric data in a DATA UJOINT statement are length units.
  5. Care should be taken in supplying accurate dimensional data since any errors result in improper shapes for the links and remain throughout the simulation. Slight errors cause inaccurate answers, while gross errors may cause completely unpredictable results.
  6. The xi,yi,zi numeric data must conform to the rules for the placement of the local coordinate systems for a universal joint (see UJOINT statement). If errors are detected, the DATA UJOINT statement is ignored and a message is printed. Certain types of errors may not be detected until an EXECUTE or EXECUTE HOLD statement is given; these cause the simulation to be halted and a message to be printed at that time.
  7. The three points for which xi,yi,zi numeric data are given need not be unit distances apart; the local u,v,w and u,v,w axes are normalized by IMP to form unit vectors. The points should not be chosen coincident or too close together, however; larger distances achieve more accurate placement of axes.
  8. Any of the xi,yi,zi groups of numeric data may be replaced by the alphanumeric name of a previously defined point for which a valid DATA POINT statement has previously been given (see above examples).

The DATA SPHERE Statement

The DATA SPHERE statement specifies the numeric data which simultaneously locate the two local coordinate systems attached to the two links on either side of a SPHERE joint relative to the absolute (global) frame of reference for the system.

The DATA SPHERE statements, taken together with the DATA statements for other types of joints and the DATA LINK statements, describe the relative locations of the various links of the system at the initial (design) position.

The initial locations of the two local coordinate systems attached to the two links joined by a SPHERE statement are both defined by a single DATA SPHERE statement by specifying the location of one point, the center of the SPHERE joint. However, IMP chooses the orientations of the local u,v,w and u,v,w axes; thus the user has no control of their orientation. If the user wishes to control the orientations of the local u,v,w and u,v,w coordinate systems, a pair of DATA LINK statements should be used rather than a DATA SPHERE statement.

Format

DATA SPHERE (joint name) = x,y,z

where joint name is the alphanumeric name of the SPHERE joint connecting the two links to which the local coordinate systems are attached. The x,y,z group is comprised of numeric values for the global coordinates of the common local origins, the location of the center of the SPHERE joint.

Examples

DATA SPHERE (BALL) = -1.0, 1.0, 1.0

specifies the initial locations of the local coordinate systems attached to the two links on either side of a SPHERE joint named BALL. The numeric data corresponds approximately to the figure.

The above example might also take either of the following forms:

DATA SPHERE (BALL) = -1,1,1
DATA SPHERE (BALL) = PT1

Notes

  1. The joint name specified must have been defined by a previous SPHERE statement. If not, the DATA SPHERE statement is ignored and a message is printed.
  2. If a DATA SPHERE statement or the two equivalent DATA LINK statements are not specified for each joint name defined by a SPHERE statement before an EXECUTE or EXECUTE HOLD statement is given, the local coordinate system(s) with missing data is (are) initially placed coincident with the link frame of reference.
  3. If more than one DATA SPHERE statement is given for the same joint name, the later statement takes precedence and earlier data are replaced.
  4. The dimensions for the x,y,z data in a DATA SPHERE statement are length units.
  5. Care should be taken in supplying accurate x,y,z data since any errors result in improper shapes for the links and remain throughout the simulation. Slight errors cause inaccurate answers, while gross errors may cause completely unpredictable results.
  6. The x,y,z group of numeric data may be replaced by the alphanumeric name of a previously defined point for which a valid DATA POINT statement has previously been given (see above example).

The DATA POINT Statement

The DATA POINT statement specifies the location of a point defined in a previous POINT statement.

Format

There are three forms of the DATA POINT statement.

The first form is used to specify the location of a point relative to one of the local joint coordinate systems attached to the link of which the point is a part:

DATA POINT (point name, joint name) = u,v,w

where point name is the alphanumeric name of the point, joint name is the alphanumeric name of the joint whose local coordinate system is used for reference, and u,v,w are the numeric values of the point's coordinates relative to this local coordinate system.

The second form is identical with the first except that joint name is replaced by the keyword LINK:

DATA POINT (point name, LINK) = x,y,z

which indicates that the local coordinate system of the link to which the point is attached is used for specifying of the x,y,z data.

The third form is also identical with the first except that joint name is replaced by the keyword ABS:

DATA POINT (point name, ABS) = X,Y,Z

which indicates that the global coordinate system is used for measurement of the numeric X,Y,Z data.

Examples

DATA POINT (PT1, JT1) = 2.0,2.0,0.0

specifies the location of a point named PT1 relative to a local coordinate system at a joint named JT1 as shown in the figure.

Three other valid specifications, which also correspond to the figure, are:

DATA POINT (PT1, JT2) = -3,2,0
DATA POINT (PT1, LINK) = 0,2,0
DATA POINT (PT1, ABS) = 2,5,0


Notes

  1. There must be a DATA POINT statement for each point defined by a POINT statement. If one does not appear before an EXECUTE or EXECUTE HOLD statement is given, the point with missing data is placed at the origin of the local link coordinate system.
  2. The point name specified must have been defined by a previous POINT statement. If not, the DATA POINT statement is ignored and a message is printed.
  3. The joint name, if specified, must have been defined in a previous statement, and it must be connected to the same link to which the point is attached. If not, the DATA POINT statement is ignored and a message is printed.
  4. If more than one DATA POINT statement is given referring to the same point name, the later statement takes precedence; earlier data are replaced and a message is printed.
  5. The u,v,w or x,y,z or X,Y,Z coordinate data have units of length.
  6. When the ABS form of the DATA POINT statement is used, the X,Y,Z data may be replaced by the alphanumeric name of a previously defined point for which a valid DATA POINT statement has already been given.

The DATA GRAVITY Statement

The DATA GRAVITY statement specifies the components of the gravitational acceleration vector relative to the global coordinatesystem. It also specifies that the weights and potential energy changes of all links which have mass should henceforth be considered in performing the simulation.

Format

DATA GRAVITY = gx,gy,gz

where gx,gy,gz are the numeric values of the global components of the gravitational acceleration vector.

Example

DATA GRAVITY = 0,-386.1,0

specifies that the acceleration of gravity is 386.1 length units per second per second in the global negative Y direction.

Notes

  1. The DATA GRAVITY statement is optional. However, if it is not included before an EXECUTE or EXECUTE HOLD statement is given, the effects of gravity, that is, the gravitational forces due to the weights of the links, are neglected in the simulation. No message is printed.
  2. Even with the DATA GRAVITY statement included, the effects of gravity are neglected for any link whose mass is not specified by SHAPE and DATA DENSITY statements or by a DATA MASS statement. No message is printed.
  3. If more than one DATA GRAVITY statement is specified, the later statement takes precedence; earlier data are replaced and a message is printed.
  4. If a FIND EQUILIBRIUM statement (static mode) or a FIND DYNAMICS statement (dynamic mode) is encountered before the EXECUTE or EXECUTE HOLD statement, a DATA GRAVITY statement causes potential energy changes due to gravity to be considered in determining the position or motion of the system. If neither of these statements is encountered (kinematic mode), potential energy changes are not considered in determining the system's position. However, gravitational forces are considered for all modes when performing constraint force analyses.
  5. The dimensions of the gravity vector are length units per second per second.
  6. Standard gravity in US Customary units is 386.088 inches per second per second.
  7. There is no assumption made that the gravitational acceleration vector has a 1.0 g magnitude. The conversion of mass units to weight units is not related to the DATA GRAVITY statement, but can be controlled by use of the UNIT (MASS) statement.


The DATA DENSITY Statement

The DATA DENSITY statement specifies the mass density for a shape defined by a SHAPE statement. The DATA DENSITY statement causes the automatic calculation of the mass, the center of mass, and the mass moments and products of inertia for that shape and updates the mass properties of the associated link using the specified material density.

Format

DATA DENSITY (shape name) = density

where shape name is the alphanumeric name of a solid which has been named in a previous SHAPE statement and density is the numeric value of the mass density of that shape's material.

Example

SOLID READ (ROD) = rod.geo
SHAPE (SHAFT) = ROD DATA DENSITY (ROD) = 0.286

specifies that the material for the shape named ROD of the link named SHAFT has mass density of 0.286 mass units per cubic length unit, and that the shape of ROD (from file rod.geo) is to be used with this density to find the mass, the center of mass location, and the mass moments and products of inertia for that part of link SHAFT.

Notes

  1. The DATA DENSITY statement is optional; it may, but need not, be used for any shape specified in a SHAPE statement.
  2. A DATA MASS and/or set of DATA DENSITY statements is necessary for all solid shapes of each link whose mass is to be considered in the simulation. Each link whose mass is not specified before an EXECUTE or EXECUTE HOLD statement is given is considered to have no kinetic energy and no gravitational potential energy. No message is printed.
  3. The shape name specified must have appeared in a previous SHAPE statement specifying that the shape name is a part of a particular link. If the link has not been named in a SHAPE statement, or if the shape name and its geometry have not been defined, before the DATA DENSITY statement is given, the DATA DENSITY statement is ignored and a message is printed.
  4. If a solid shape has been defined for a part of a link with a SHAPE statement, the DATA DENSITY statement should be used rather than the DATA MASS or DATA INERTIA statements in order to ensure consistency with the defined part shape. If no shape has been defined by a SHAPE statement a DATA MASS and DATA INERTIA statement should be used instead.
  5. If both DATA DENSITY and DATA MASS and DATA INERTIA statements are used for the same link or its subordinate solid parts, the DATA MASS and DATA INERTIA statements should be given first for the portion of the link which has no defined shape. DATA DENSITY statements given after this for solid part shapes of the same link then cause the total mass of the link and its distribution to be properly incremented.
  6. If more than one DATA DENSITY statement is given for the same shape name, the total mass and mass distribution of the link are incremented multiple times, thus causing an error; no message is printed. Notice, however, that different DATA DENSITY statements may be used for the different shape names attached to the same link name. The total mass properties of the link will then include the combination of all sub-shapes of the total geometry of the link.
  7. If more than one DATA MASS or DATA INERTIA statement is given for the same link name, the later data takes precedence and earlier data are replaced. Notice, however, that the increments caused by earlier DATA DENSITY statements for shape names on this link are lost.
  8. The density value has units of mass per cubic length. When using inches, seconds, and pounds force, for example, and density has units of pounds mass per cubic inch, then a UNIT MASS = 0.002950l statement must be in effect at the time that the DATA DENSITY statement is issued. When using meters, seconds, and newtons, the density is given in kilograms per See the UNIT MASS cubic meter and UNIT (MASS) = 1.0. statement in Chapter 6 for more details.
  9. If a FIND EQUILIBRIUM statement (static mode) or a FIND DYNAMICS statement (dynamic mode) and a DATA GRAVITY statement are encountered before an EXECUTE or EXECUTE HOLD statement, potential energy changes due to gravity are considered in determining the position or motion of the system. If a FIND EQUILIBRIUM or FIND DYNAMICS statement does not appear (kinematic mode), gravitational potential energy is not considered in determining the system's position. In all modes, however, gravity is considered in constraint force analysis if a DATA GRAVITY statement is given.
  10. If a FIND DYNAMICS statement (dynamic mode) is encountered before the EXECUTE or EXECUTE HOLD statement, the kinetic energies of all links for which valid DATA DENSITY or DATA MASS and DATA INERTIA statements are specified are considered in determining the motion of the system. In either kinematic or dynamic mode, the kinetic energies of all moving masses are considered in constraint force analysis.


The DATA MASS Statement

The DATA MASS statement specifies the mass and the location of the center of mass of one link of the system.

Format

DATA MASS (link name, joint name) = m; u,v,w

where link name is the alphanumeric name of the link, m is the numeric value of the mass of the link and u,v,w are the numeric values of the coordinates of the center of mass of the link measured relative to the local coordinate system attached to link name at the joint with the alphanumeric name joint name.

Example

DATA MASS (ROD, UJNT) = 0.5; 3.25,0.0,0.0

specifies that the mass of the link named ROD is 0.5 mass units, and that its center of gravity is located at u=3.25, v=0, and w=0, relative to the local coordinate system attached to ROD at the joint named UJNT.

Notes

  1. The DATA MASS and DATA DENSITY statements are optional; they may be used repeatedly to specify masses for as many or as few links as desired.
  2. A separate DATA MASS or set of DATA DENSITY statements is necessary for each link whose mass is to be considered in the simulation. Each link whose mass is not specified before an EXECUTE or EXECUTE HOLD statement is given is considered to have no kinetic energy and no gravitational potential energy. No message is printed.
  3. The link name specified must have appeared in at least one previous statement defining a link or a joint. If not, the DATA MASS statement is ignored and a message is printed.
  4. The keyword LINK can be used in place of a joint name; if this is done if signifies that x,y,z data are specified with respect to the coordinate system of link name instead of u,v,w data.
  5. Unless the keyword LINK is used, the joint name specified must have been defined in a previous statement defining a joint, and it must be a connection for the same link name for which the mass is specified. If not, the DATA MASS statement is ignored and a message is printed.
  6. If both DATA DENSITY and DATA MASS and DATA INERTIA statements are used for the same link or its subordinate solid part shapes, the DATA MASS and DATA INERTIA statements should be given first for the portion of the link which has no defined shape. DATA DENSITY statements given after this for solid part shapes of the same link then cause the total mass of the link and its distribution to be properly incremented.
  7. If more than one DATA MASS or DATA INERTIA statement is given for the same link name, the later data takes precedence and earlier data are replaced. Notice, however, that the increments caused by any earlier DATA DENSITY statements for shape names on this link are lost; no message is printed.
  8. The m value has units of mass; the u,v,w or x,y,z coordinates have units of length. When using inches, seconds, and pounds force, m has units of pounds mass; then a UNIT MASS = 0.0025901 statement must be in effect at the time the DATA MASS statement is issued. When using meters, seconds, and newtons, then m is given in kilograms and UNIT MASS = 1.0. See the UNIT MASS statement in Chapter 6.
  9. When a DATA MASS statement is given, mass data for a point mass located at the center of gravity of the specified link name are stored; appropriate mass moments and products of inertia relative to the designated joint name local coordinate system are also stored. A subsequent DATA INERTIA statement may then be used, if desired, to specify distributed mass moments and products of inertia.
  10. A DATA MASS or DATA DENSITY statement may be specified for the fixed link if desired, but has no effect on the simulation.
  11. If a FIND EQUILIBRIUM statement (static mode) or a FIND DYNAMICS statement (dynamic mode) and a DATA GRAVITY statement are encountered before the EXECUTE or EXECUTE HOLD statement, potential energy changes due to gravity are considered in determining the position or motion of the system. If a FIND EQUILIBRIUM or FIND DYNAMICS statement does not appear (kinematic mode), gravitational potential energy is not considered in determining the system's position. In all modes, however, gravity is considered in constraint force analysis if a DATA GRAVITY statement is given.
  12. If a FIND DYNAMICS statement (dynamic mode) is encountered before the EXECUTE or EXECUTE HOLD statement, the kinetic energies of all links for which DATA MASS or DATA DENSITY statements are specified are considered in determining the motion of the system. In either kinematic or dynamic mode, the kinetic energies of all moving masses are considered in constraint force analysis.


The DATA INERTIA Statement

The DATA INERTIA statement may be used to specify the distributed mass moments and products of inertia of a link for which a DATA MASS statement has been given.

Format

DATA INERTIA (link name, joint name) = Ixx,Iyy,Izz,Ixy,Ixz,Iyz

where link name is the alphanumeric name of the link and Ixx,Iyy,...,Iyz are the numeric values of the mass moments and products of inertia measured relative to the local u,v,w coordinate system attached to link name at the joint with the alphanumeric name joint name.

Example

DATA INERTIA (ROD, UJNT) = 0.002,16.7,16.7,0.0,0.0,0.0

specifies the mass moments and products of inertia of a link named ROD relative to the local u,v,w coordinate system at the joint named UJNT.

Notes

  1. Use of the DATA INERTIA statement is optional; it may be used repeatedly to specify distributed inertia properties for as many or as few links as desired.
  2. If a DATA INERTIA statement is used, a DATA MASS statement must have been previously specified for the same link name. If not, the DATA INERTIA statement is ignored and a message is printed.
  3. The keyword LINK can be used for joint name; if this is done it signifies that the Ixx,Iyy,...,Iyz data are spec- ified with respect to the x,y,z coordinate system of link name.
  4. The joint name specified must have been previously defined, and must be a connection for the same link name for which the mass moments and products of inertia are specified. If not, the DATA INERTIA statement is ignored and a message is printed.
  5. The joint name specified need not be the same as the joint name used in the corresponding DATA MASS statement, although this is permitted and is often convenient.
  6. If both DATA DENSITY and DATA MASS and DATA INERTIA statements are used for the same link or its subordinate solid part shapes, the DATA MASS and DATA INERTIA statements should be given first for the portion of the link which has no defined shape. DATA DENSITY statements given after this for solid part shapes of the same link then cause the total mass of the link and its distribution to be properly incremented.
  7. If more than one DATA MASS or DATA INERTIA statement is given for the same link name, the later data takes precedence and earlier data are replaced. Notice, however, that the increments caused by any earlier DATA DENSITY statements for shape names on this link are lost; no message is printed.
  8. The units for the mass moments and products of inertia are mass length squared (for example, pounds mass inches squared or kilogram meters squared). See the UNIT MASS statement in Chapter 6 for further discussion.
  9. When a DATA MASS statement is given, data for a point mass located at the specified center of mass of that link are stored. Appropriate mass moments and products of inertia for a point mass are also stored relative to the designated joint name local coordinate system. A subsequent DATA INERTIA statement may then be used to specify distributed mass moments and products of inertia if desired.
  10. A DATA INERTIA statement may be specified for the fixed link if desired, but has no effect on the simulation.


The DATA SPRING Statement

There are two uses of the DATA SPRING statement. One use is to specify the rate and free length of a spring defined by a previous SPRING statement. The other use is to specify the rates (stiffness) and free (unloaded) positions of springs acting with the joint variable(s) of a previously defined joint.

Format

DATA SPRING (name) = rate,position; rate,position; ...

where name is the alphanumeric name of a previously defined spring or joint. If name was defined by a previous SPRING statement, then only one rate and position are specified; if name refers to a joint, then a rate and position are specified for each joint variable in succession. Each rate is the numeric value of a spring rate or joint stiffness and each position is the numeric length of a spring or value of a joint variable for which the spring or joint stiffness produces no load.

Examples

DATA SPRING (PULL) = 100.0, 5.25

specifies that a spring named PULL has a rate of 100.0 force units per unit deflection, and a free length of 5.25 length units.

DATA SPRING (PIN) = K, -45

specifies that there is torsional stiffness in the joint named PIN. The stiffness is defined by a previous VALUE expression with the name K (see note 6), and the joint is in an unloaded position when the joint variable has a value of -45°.

DATA SPRING (CYL) = NONE, NONE; 1200,2.5

specifies that a cylindric joint named CYL has no rotational stiffness along with the first joint variable (see note 7), but does have a translational stiffness acting with the second joint variable. The translational stiffness is 1200 force units per unit deflection, and there is no force transmitted when the second joint variable (the translation) has a value of 2.5 length units.

Notes

  1. There must be a DATA SPRING statement for each spring defined by a SPRING statement. If these do not appear before the EXECUTE or EXECUTE HOLD statement, any spring with undefined data is deleted and a message is printed at that time.
  2. DATA SPRING statements need not be given for all joints, but may be used for as many or few as desired.
  3. The name specified must have been defined by a previous SPRING statement or joint definition statement. If not, the DATA SPRING statement is ignored and a message is printed.
  4. If more than one DATA SPRING statement is encountered using the same name, the later data takes precedence; earlier data are replaced and a message is printed.
  5. The units for the rate of a tension or compression spring are force per unit length of deflection from the free position. The rate of a torsion spring has units of torque per degree of deflection from the free position. The free position has units of length or degrees.
  6. The numeric value of any rate or position may be substituted for by the alphanumeric name of a previously defined VALUE expression. In such a case, however, the units of a VALUE expression for a torsion rate must be torque per radian and the units of a VALUE expression for a rotational position must be radians.
  7. The keyword NONE may be used in place of any rate and position for any joint variable for which no stiffness is intended. If the keyword NONE is used for a rate or position value, NONE is also used for the other value.


The DATA DAMPER Statement

There are two uses for the DATA DAMPER statement. One use is to specify the damping coefficient of a viscous damper defined by a DAMPER statement. The other use is to specify the coefficients of viscous damping acting within the joint variable(s) of a previously defined joint.

Format

DATA DAMPER (name) = coefficient, coefficient, ...

where name is the alphanumeric name of a previously defined damper or joint. If name was defined by a previous DAMPER statement, then only one coefficient is given; if name refers to a joint, then a coefficient is given for each joint variable in succession. Each coefficient is the numeric value of a damping coefficient.

Examples

DATA DAMPER (SLOW) = 4.75

specifies that a viscous damper named SLOW has a damping coefficient of 4.75 force seconds per unit length.

DATA DAMPER (LOSS) = C

specifies that there is viscous damping in a revolute joint named LOSS. The damping coefficient is defined by a previous VALUE expression named C (see note 6).

DATA DAMPER (CYL) = 0.15, NONE

specifies that there is viscous damping of 0.15 force length seconds per radian resisting the motion of the first joint variable (rotation) of a cylindric joint named CYL, but no damping with the motion of the second joint variable, the translation (see note 7).

Notes

  1. There must be a DATA DAMPER statement for each damper defined by a DAMPER statement. If these do not appear before the EXECUTE or EXECUTE HOLD statement, any damper with undefined data is deleted and a message is printed at that time.
  2. DATA DAMPER statements need not be given for all joints, but may be used for as many or as few as desired.
  3. The name specified must have been defined by a previous DAMPER statement or a joint definition statement. If not, the DATA DAMPER statement is ignored and a message is printed.
  4. If more than one DATA DAMPER statement is encountered using the same name, the later data takes precedence; earlier data are replaced and a message is printed.
  5. The units for the coefficient of a translational damper are force seconds per unit length; for a torsional damper, the units are force length seconds per radian.
  6. The numeric value of any coefficient may be substituted for by the alphanumeric name of a previously defined VALUE expression.
  7. The keyword NONE may be used in place of any coefficient for a joint variable for which no damping is intended.


The DATA FORCE Statement

There are two uses for the DATA FORCE statement. One use is to specify the magnitude of an externally applied force defined by a FORCE statement. The other use is to specify the magnitudes of pairs of equal and opposite forces or torques applied along each of the joint variables of a previously defined joint.

Format

DATA FORCE (name) = force, force, ...

where name is the alphanumeric name of a previously defined force or joint. If name was defined by a previous FORCE statement, then only one force is given; if name refers to a joint, then a force is given for each joint variable in succession. Each force is the numeric value of an applied force or torque.

Examples

DATA FORCE (PUSH) = -100

specifies that an externally applied force named PUSH has a magnitude of -100 force units.

DATA FORCE (PULL) = F

specifies that a force named PULL has a magnitude defined by a previous VALUE expression named F (see note 7).

DATA FORCE (CYL) = NONE, 15.2

specifies that there is no externally applied torque acting on the rotational joint variable of the cylindric joint named CYL (see note 8), but that equal and opposite forces of magnitude 15.2 force units are applied along the translational joint variable.

Notes

  1. There must be a DATA FORCE statement for each force defined by a FORCE statement. If these do not appear before the EXECUTE or EXECUTE HOLD statement, any force with undefined data is deleted and a message is printed at that time.
  2. DATA FORCE statements need not be given for all joints, but may be used for as many or as few as desired.
  3. The name specified must have been defined by a previous FORCE statement or a joint definition statement. If not, the DATA FORCE statement is ignored and a message is printed.
  4. If more than one DATA FORCE statement is encountered using the same name, the later statement takes precedence; earlier data are replaced and a message is printed.
  5. The units for a force are force units if the name refers to a FORCE statement. If the name refers to a joint, then units of force are used for a translational joint variable force and units of length force are used for a rotational joint variable force.
  6. The sign of the force value must be consistent with the order of the point names specified in the FORCE statement. A force value applied within a joint is considered positive if it tends to change the value of the joint variable in the positive sense.
  7. The numeric value of any force may be substituted for by the alphanumeric name of a previously defined VALUE expression.
  8. The keyword NONE may be used in place of any force for a joint variable for which no externally applied force is intended.


The DATA TORQUE Statement

There are two uses for the DATA TORQUE statement. One use is to specify the magnitude of an externally applied torque defined by a TORQUE statement. The other use is to specify the magnitudes of pairs of equal and opposite forces or torques applied along each of the joint variables of a previously defined joint.

Format

DATA TORQUE (name) = torque, torque, ...

where name is the alphanumeric name of a previously defined torque or joint. If name was defined by a previous TORQUE statement, then only one torque is given; if name refers to a joint, then a torque is given for each joint variable in succession. Each torque is the numeric value of an applied torque or force.

Examples

DATA TORQUE (TWIST) = -100

specifies that an externally applied torque named TWIST has a magnitude of -100 torque units.

DATA TORQUE (TURN) = F

specifies that a torque named TURN has a magnitude defined by a previous VALUE expression named F (see note 7).

DATA TORQUE (CYL) = 15.2, NONE

specifies that there are equal and opposite externally applied torques acting on the rotational joint variable of the cylindric joint named CYL, but that no force is applied along the translational joint variable (see note 8).

Notes

  1. There must be a DATA TORQUE statement for each torque defined by a TORQUE statement. If these do not appear before the EXECUTE or EXECUTE HOLD statement, any torque with undefined data is deleted and a message is printed at that time.
  2. DATA TORQUE statements need not be given for all joints but may be used for as many or as few as desired.
  3. The name specified must have been defined by a previous TORQUE statement or a joint definition statement. If not, the DATA TORQUE statement is ignored and a message is printed.
  4. If more than one DATA TORQUE statement is encountered using the same name, the later statement takes precedence; earlier data are replaced and a message is printed.
  5. The units for a torque are length force if the name refers to a TORQUE statement. If the name refers to a joint, then units of force are used for a translational joint variable torque and units of length force are used for a rotational joint variable torque.
  6. The sign of the torque value must be consistent with the order of the point names specified in the TORQUE statement. A torque value applied within a joint is considered positive if it tends to change the value of the joint variable in the positive sense.
  7. The numeric value of a torque may be substituted for by the alphanumeric name of a previously defined VALUE expression.
  8. The keyword NONE may be used in place of a torque for a joint variable for which no externally applied torque is intended.


The DATA CONTACT Statement

The DATA CONTACT statement is used to specify the properties of a pair of contacting solids defined by a CONTACT statement.

Format

DATA CONTACT (contact name) = en, et, eb, er, mu

where contact name is the alphanumeric name of a previously defined contact, en, et, and eb are the coefficients of restitution in the normal, tangential, and binormal directions, respectively, er is the torsional coefficient of restitution, and mu is the coefficient of Coulomb friction, all taken with respect to the impacting surfaces of the contact.

Examples

DATA CONTACT (HIT) = 0.9, -1.0, 0.0, -1.0, 0.25

specifies that a CONTACT named HIT has coefficients of restitution of 0.9, -1.0, 0.0, and -1.0 in the normal, tangential, binormal, and torsional directions, respectively, and a coefficient of Coulomb friction of 0.25 units.

Notes

  1. There may be a DATA CONTACT statement for each contact defined by a CONTACT statement. If these do not appear before the EXECUTE or EXECUTE HOLD statement, any contacts without such data are given default data of en=0.0, et=0.0, ebi=-1.0, emn=0.0, and mu=0.0; no message is printed.
  2. DATA CONTACT statements need not be given for all contacts but may be used for as many or as few as desired.
  3. The contact name specified must have been defined by a previous CONTACT statement. If not, the DATA CONTACT statement is ignored and a message is printed.
  4. If more than one DATA CONTACT statement is encountered using the same contact name, the later statement takes precedence; earlier data are replaced; no message is printed.
  5. The numeric values of the coefficients of restitution are unity for purely elastic (no loss of relative velocity on rebound) and zero for plastic (total loss of relative velocity with no rebound); the values are positive for a direction reversal and negative for no direction reversal of the relative velocity during impact.
  6. The coefficient of Coulomb friction mu is always non-negative, but may be zero.
  7. Which of the five coefficients are used for a given contact name depend on the settings of the impact models specified by the most recent IMPACT statement at the time that an EXECUTE or EXECUTE HOLD statement is encountered.


The DATA POSITION Statement

The DATA POSITION statement designates a single degree of freedom joint as a position input (SGC) for the system in the kinematic or static mode and specifies the initial position, increment size, and number of increments for its joint variable during the simulation.

Format

DATA POSITION (joint name) = position, increment, n steps

where joint name is the alphanumeric name of the REVOLUTE or PRISM or XPIN or YPIN or ZPIN or XSLIDE or YSLIDE or ZSLIDE or GEAR or BEVEL or RACK or SCREW joint being designated as an SGC, position is the numeric value of the joint variable at the first position to be simulated, increment is the numeric value of the increment to be made in that joint variable value for each print, and n steps is the integer number of increments to be made in that joint variable during the simulation.

Examples

DATA POSITION (PIN) = -90.0, 15.0, 24

specifies that the previously defined REVOLUTE joint named PIN is an SGC for the system and is to be incremented from -90° to 270° in equal steps of 15° each.

DATA POSITION (SLIP) = 1.75

specifies that the PRISM joint named SLIP is an SGC for the system and its joint variable is held stationary at a value of 1.75 length units throughout the simulation.

Notes

  1. The DATA POSITION statement may not be used after a FIND DYNAMICS statement (dynamic mode). If this is attempted, the DATA POSITION statement is ignored and a message is printed.
  2. The DATA POSITION statement is optional; it may be used along with the DATA MOTION statement for as few or as many joints as desired up to the number of degrees of freedom of the system.
  3. If more DATA POSITION and/or DATA MOTION statements are specified than there are degrees of freedom in the system, no error is detected immediately. During the simulation, however, a diagnostic message will occur unless the position data are all specified (with extreme precision) consistent with a configuration for which the system can be assembled. Difficulty will certainly result upon incrementing to a new position.
  4. If less DATA POSITION and/or DATA MOTION statements are specified than the number of degrees of freedom of the system, additional joint variables are selected as free generalized coordinates (FGCs) by the IMP system.
  5. If a FIND EQUILIBRIUM statement is encountered before the EXECUTE or EXECUTE HOLD statement (static mode), then any FGC positions are varied to move the system to a position of static equilibrium. If not (kinematic mode), then no control is exerted over the values of the FGCs; they usually retain their original positions.
  6. The joint name specified must be defined by a previous statement defining a single degree of freedom joint. If not, the DATA POSITION statement is ignored and a message is printed.
  7. If more than one DATA POSITION or DATA MOTION statement is encountered referring to the same joint name, the later statement takes precedence; earlier data are replaced and a message is printed.
  8. If only a single position of a particular joint variable is intended, the values of increment and n steps need not be specified; when not specified increment and n steps are treated as zero.
  9. If the value of increment is given as zero, then n steps is also treated as zero.
  10. The units of position and increment are degrees for a rotational joint or length units for a sliding joint.
  11. The sign of the position and increment values must be consistent with the sign convention of the joint variable (see statement defining the joint).
  12. If an SGC joint variable value is set to or incremented to a position which cannot be achieved by the system model, this position is ignored and the simulation is continued at the next position; a message is printed.
  13. When a position is specified for a joint variable by a DATA POSITION statement, it is assumed to have zero velocity and zero acceleration until otherwise specified by a DATA VELOCITY or DATA ACCEL statement.
  14. The starting position specification need not be the design position, but should not be too far away from it.
  15. When a DATA POSITION or DATA MOTION statement is used to set a particular joint variable to a specified position, this implies that sufficient force or torque is applied at that joint variable to achieve that position even though no DATA FORCE or DATA TORQUE statement has been given.


The DATA VELOCITY Statement

The DATA VELOCITY statement specifies the velocity of a joint variable which was specified as an SGC by a previous DATA POSITION statement.

Format

DATA VELOCITY (joint name) = velocity

where joint name is the alphanumeric name of a joint which was previously designated in a DATA POSITION statement, and velocity is the numeric value of the joint variable velocity for that joint.

Example

DATA VELOCITY (PIN) = -188.5

specifies that velocity of the pinned joint named PIN is -188.5 radians per second (1800 rpm) clockwise.

Notes

  1. A DATA VELOCITY statement may not be used after a FIND EQUILIBRIUM statement (static mode) or a FIND DYNAMICS statement (dynamic mode). If this is attempted, the DATA VELOCITY statement is ignored and a message is printed.
  2. The joint name specified must have been defined as an SGC by a previous DATA POSITION statement referring to the same joint name. If not, the DATA VELOCITY statement is ignored and a message is printed.
  3. If more than one DATA VELOCITY statement is encountered referring to the same joint name, the later statement takes precedence; earlier data are replaced and a message is printed.
  4. Not every SGC designated by a DATA POSITION statement need be given a velocity. Those not given velocities by DATA VELOCITY statements are treated as having zero velocities.
  5. If more than one position of the system is simulated, the velocity specified is the same for all positions even though a DATA ACCEL statement may be given.
  6. The units of velocity are radians per second for a rotational joint or length units per second for a sliding joint.
  7. The sign of the velocity must be consistent with the sign convention for the joint variable (see statement defining the joint).


The DATA ACCEL Statement

The DATA ACCEL statement specifies the acceleration of a joint variable which was specified as an SGC by a previous DATA POSITION statement.

Format

DATA ACCEL (joint name) = acceleration

where joint name is the alphanumeric name of a joint which was previously designated in a DATA POSITION statement, and acceleration is the numeric value of the joint variable acceleration for that joint.

Example

DATA ACCEL (PIN) = 50.0

specifies that acceleration of the SGC revolute joint named PIN is 50.0 radians per second per second.

Notes

  1. A DATA ACCEL statement may not be used after a FIND EQUILIBRIUM statement (static mode) or a FIND DYNAMICS statement (dynamic mode). If this is attempted, the DATA ACCEL statement is ignored and a message is printed.
  2. The joint name specified must be defined as an SGC by a previous DATA POSITION statement referring to the same joint name. If not, the DATA ACCEL statement is ignored and a message is printed.
  3. If more than one DATA ACCEL statement is encountered referring to the same joint name, the later statement takes precedence; earlier data are replaced and a message is printed.
  4. Not every SGC designated by a DATA POSITION statement need be given acceleration. Those not given acceleration by DATA ACCEL statements are treated as having zero acceleration.
  5. If more than one position of the system is simulated, the acceleration specified is the same for all positions.
  6. The units of acceleration are radians per second per second for a rotating joint or length units per second per second for a sliding joint.
  7. The sign of the acceleration must be consistent with the sign convention for the joint variable joint (see statement defining the joint).


The DATA MOTION Statement

The DATA MOTION statement designates one or more joint variables as motion input(s),(SGCs), for the system and specifies their motion(s).

Format

DATA MOTION (joint name) = position, position, ...

where joint name is the alphanumeric name of the joint whose joint variables are to be motion inputs (SGCs). There is one position value specified for each joint variable in order; each position is a numeric value or the alphanumeric name of a VALUE expression specifying the position of that joint variable.

Examples

DATA MOTION (PIN) = -90.0

specifies that the previously defined REVOLUTE joint named PIN is held stationary, with its joint variable value set to -90° throughout the simulation.

DATA MOTION (SLIP) = RAMP

specifies that the PRISM joint named SLIP is an SGC; its motion is defined by a previous VALUE expression named RAMP (see note 8).

DATA MOTION (CYL) = 30.0, NONE

specifies that, in the cylindric joint named CYL, the rotational joint variable is held stationary at a value of 30.0E; the translational joint variable is not an SGC (see note 9).

Notes

  1. The DATA MOTION statement is optional; it may be used along with DATA POSITION or DATA IC statements for as few or as many joint variables as desired up to the number of degrees of freedom of the system.
  2. If more DATA MOTION, DATA POSITION, and/or DATA IC statements are specified than allowed by the degree of freedom of the system, no error is detected immediately. During the simulation, however, a diagnostic message will occur unless the position data are all specified (with extreme precision) consistent with a configuration for which the system can be assembled. Difficulty will certainly result upon attempting to increment to a new position.
  3. If DATA MOTION, DATA POSITION, and/or DATA IC statements are specified for less joint variables than the degrees of freedom of the system, additional joint variables are selected as free generalized coordinates (FGCs) by the IMP system.
  4. The joint name specified must be defined by a previous statement defining a joint. If not, the DATA MOTION statement is ignored and a message is printed.
  5. If more than one DATA MOTION, DATA POSITION, or DATA IC statement is encountered referring to the same joint name, the later statement takes precedence; earlier data are replaced and a message is printed.
  6. The units of each position value depend on the nature of the joint variable; degrees are used for each rotational joint variable (also see note 8) and length units for each translational joint variable.
  7. The sign of each position value must be consistent with the sign convention for the corresponding joint variable (see joint definition statement).
  8. The numeric value of any position may be substituted for by the alphanumeric name of a previously defined VALUE expression. In such a case, however, the units of a rotational joint variable VALUE expression must be radians.
  9. The keyword NONE may be used in place of any position value for a joint variable which is not intended as an SGC.
  10. If a numeric value is used for position, the velocity and acceleration of the corresponding joint variable are assumed to be zero. When a VALUE expression name is used for position, proper derivative values are used to provide the corresponding velocity and acceleration. Note, however, that VALUE expressions using the VELOCITY, ACCELERATION, or FORCE functions may return undefined values for the derivatives. Undefined values are treated as zeroes in their use in the DATA MOTION statement.
  11. When a DATA MOTION statement is used, this implies that sufficient force or torque is applied at each joint variable to achieve the specified motion even though no DATA FORCE or DATA TORQUE statement has been given.


The DATA IC Statement

The DATA IC statement specifies the initial positions and velocities of the joint variables of a designated joint for the start of a dynamic mode simulation.

Format

DATA IC (joint name)=position,velocity;position,velocity;...

where joint name is the alphanumeric name of the joint whose initial conditions are specified. Each position and velocity pair are the numeric values for the initial position and velocity of one joint variable; there is one position,velocity pair of values specified for each joint variable in order.

Examples

DATA IC (PIN) = -90, 12.566

specifies that the initial conditions for the pinned joint named PIN for a dynamic mode simulation are to have its joint variable set to -90° with an initial velocity of 12.566 radians per second (2 Hz).

DATA IC (SLIP) = POS VEL

specifies that the dynamic mode simulation will begin with initial conditions for the sliding joint named SLIP defined by previous value expressions named POS and VEL (see note 9).

DATA IC (CYL) = 30,12.566; NONE, NONE

specifies that, for the cylindric joint named CYL, the rotational joint variable has initial conditions of 30° and 12.566 radians per second, while the translational joint variable has no initial conditions specified (see note 10).

Notes

  1. The DATA IC statement must be preceded by a FIND DYNAMICS statement (dynamic mode); if not, the statement is ignored and a message is printed.
  2. The DATA IC statement is optional; it may be used along with the DATA MOTION statement for as few or many joint variables as desired up to the number of degrees of freedom of the system.
  3. If more DATA MOTION and DATA IC statements are specified than allowed by the degree of freedom of the system, no error is detected immediately. During the simulation, however, a diagnostic message will occur unless the position data are all specified (with extreme precision) consistent with a configuration for which the system can be assembled. Difficulty will certainly result upon attempting to increment to a new position.
  4. If DATA MOTION and DATA IC statements are specified for less joint variables than the degree of freedom of the system, additional joint variables are selected as free generalized coordinates (FGCs) by the IMP system. The initial conditions for these additional FGCs are determined by IMP; the initial velocities of these additional FGCs are assumed zero.
  5. The name specified must be defined by a previous statement defining a joint. If not, the DATA IC statement is ignored and a message is printed.
  6. If more than one DATA IC or DATA MOTION statement is encountered referring to the same joint name, the later statement takes precedence; earlier data are replaced and a message is printed.
  7. The units of each position and each velocity value depend upon the nature of each joint variable. For rotational joint variables, the units of position are degrees (also see note 9), and the units of velocity are radians per second; for each translational joint variable, each position has units of length, while each velocity has units of length per second.
  8. The sign of each position and each velocity value must be consistent with the sign convention for the corresponding joint variable (see joint definition statement).
  9. The numeric value of any position or any velocity may be substituted for by the alphanumeric name of a previously defined VALUE expression. In such a case, however, the units of a rotational joint variable position value must be radians.
  10. The keyword NONE may be used in place of any position and velocity value for a joint variable for which initial conditions are not intended to be specified. When NONE is used for either the position or the velocity of a joint variable, the other value for the same joint variable is also treated as NONE.

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