Creating User-defined Inverse Kinematics

You can provide your own inverse kinematic routine as an external DLL.

An example user inverse kinematics routine is provided that computes the inverse kinematics solution (set of joint variables). The interface for the C-style function is well-defined to integrate with DELMIA kinematics and simulation, and provides the availability of the kinematic parameters, robot, and desired TCP.

This task shows you how to:

Create the customized DLL

You can create a Dynamic Link Library (DLL) that defines your own routine for inverse kinematics.

An example kinematic routine for user-defined inverse kinematics is provided in the following location of your V6 installation:

<V6_install_dir>\startup\DNBUserKinematics\kin_exmpl.c

  1. Copy the example file (kin_exmpl.c).

    Note: It is recommended that you work on a copy of the example file to preserve the original.

  2. Edit the copy of the example file according to your needs.

    The kinematic routine provided for creating a user-defined DLL has the following signature:

    DllExport int
kin_user( link_lengths, link_offsets, T6, solutions, warnings, pData )

    The parameters accepted by the function are defined as follows:

    ParameterTypeInput/OutputDescription
    link_lengths[]doubleinputDistance between joint axis along link length, as per D-H (Denevitt-Hartenburg) representation.
    link_offsets[]doubleinputOffset between joint axis along joint axis, as per D-H representation.
    T6[4][4]doubleinput4x4 position matrix of center of wrist. This is the goal point MINUS the tool frame and mounting plate offsets.
    solutions[][]doubleoutputA two dimensional array contains all possible solutions for robot arm. You define how many solutions are possible, and provide all solutions when routine is called: elbow up, elbow down, etc.
    warnings[]intoutputArray providing warning states for each solution Possible warning states are:
    • WARN_GOOD_SOLUTION
    • WARN_JOINT_LIMIT_EXCEEDED
    • WARN_UNREACHABLE
    • WARN_SINGULAR_SOLUTION
    pDatavoid*inputPointer to data structure containing important kinematic parameters of the robot.

  3. Replace the original routine name in the makefile to reflect the name of the copy that you have edited.

    Note: The example makefile is provided in the same location as kin_exmpl.c.

  4. Run the following command to compile the routine into a DLL

    nmake all

  5. Copy the resulting DLL to the proper location.

    To use the new DLL, it must be present in either the CAT_STARTUP_PATH or the location defined by the DLM_USR_KIN_LIB_PATH environment variable.

Use the customized DLL in Equipment Design

Once compiled and moved to the proper location, you can specify your new DLL in Equipment Design.

  1. Select Inverse Kinematics

    The Inverse Kinematic Attributes dialog box appears.

  2. Select User Inverse as the Solver Type.
  3. Select Advanced.
  4. Select the Solver Attributes (User Defined) tab.
  5. Specify the Shared Library Name and Routine Name to reflect the name of your compiled DLL and the routine defined in the C function.
  6. Specify any Link Parameters (Lengths and Offsets) as necessary.
  7. Select OK.