Creating a Position Law Excitation

You can use a law excitation to drive a command in your mechanism by associating a value for the command to each time step of the kinematics or dynamics simulation. To define the command values, you can use a Knowledge law, rule, formula, or design table.

For each time increment specified in the kinematics or dynamics scenario parameters, the simulation uses the excitation value to determine the configuration of the mechanism.

Before you begin: Open a kinematics or a dynamics simulation referencing a mechanism in the Mechanical Systems Experience app.
See Also
About Interpolation of Time Increments
Creating a Kinematics Scenario
  1. From the Scenario section of the action bar, click Law Excitation .
  2. In the tree, under the mechanism representation node, select the command to drive with the excitation.

    Tip: Alternatively, select the command in the tree, and click Law Excitation .

    Depending on the command you selected, Length formula or Angle formula appears in the Law Excitation dialog box.
  3. Specify a name for the excitation.
  4. To define the excitation using a formula, do one of the following:
    • Click .
    • Right-click the Length formula or Angle formula box, and select Formula > Edit.

    For more information, see About Writing Formulas for Law Excitations.

  5. To define the excitation using a design table, from the Tools section of the action bar, click Design Table .
    The design table appears in the Length formula or Angle formula box.
    Note: To edit the design table, click .

    For more information, see About Using Design Tables for Law Excitations.

  6. To modify the maximum force or torque the excitation can develop to reach its position or velocity:
    1. Click Edit Maximum Torque or Edit Maximum Force, depending on the command type.
    2. Click the arrows to increase or decrease the value.

      Tip: To modify the time step, right-click the value, and select Change Step.

    Note: During a dynamics simulation using the Symplectic Euler integrator, the maximum force or torque value is taken into account to prevent movement when joint limits are reached or when contacts occur.
    Important: The mechanism movement may be partial or may not reach the specified target when:
    • the internal torque or force required to move the mechanism exceeds the maximum value.
    • a joint limit is reached
    • a contact occurs.

  7. Click OK to save the excitation.