Joint Limits

Limit how far a joint can translate or rotate, without the need for physical geometry and motion contact (such as hard stops).

Note: Currently, limits are supported in all Inspire Motion joint types except Ball & Socket.
Figure 1. Example: Rotational Limit


Figure 2. Example: Translational Limit


Define the Limits

Define the translational and rotational limits of joints.

Tip: To create the effect of one part's movement being limited by another (similar to a motion contact), you can use the Measure tool to determine the distance the part travels before contacting the second part.

In this example, you would set the limit to 50 mm if you want the block to stop at the end of the slide.



  1. Double-click a joint to edit it.
  2. In the microdialog, turn on Limits. By default, limits are turned on for all degrees of freedom of the joint.
  3. In the modeling window, click on a limit arrow to activate and define limit values. To resize the arrows so that they are easier to manipulate, see Resize the Limit Arrows.
  4. You can do the following:
    To Do this Notes
    Define the limit values
    • In the modeling window, drag a limit arrow in the direction the joint should move.
    • Or enter values in the microdialog or Property Editor.
    • For rotational limits, as you drag the arrow, a blue region is highlighted to indicate the range of movement allowed.

    • For translational limits, as you drag the arrow, a blue plane is displayed to indicate the stopping point.
    Flip the limit values, when the limit is the opposite of what is expected In the microdialog, click Flip limit . If a joint is between the ground and a moving part, the limit can be viewed as preventing movement of the moving part. If the limit is between two moving parts, the limit can be seen as preventing movement of the first part listed next to Parts in the Property Editor.
    Reset a value to 0 In the microdialog, click next to the corresponding value.
    Turn on/off a limit, for joints with more than one degree of freedom In the microdialog or Property Editor, turning on/off the corresponding Rot or Trans.
  5. Right-click and mouse through the check mark to exit, or double-right-click.

Resize the Limit Arrows

Resize the limit arrows so that they are easier to manipulate.

  1. In the Joint microdialog or Property Editor, turn off Limits.
  2. Do one of the following:
    • Drag the white arrow.
    • Or enter a Graphic Scale.

  3. In the modeling window, click on empty space to exit graphic sizing mode.
  4. Select the joint to enter editing mode.
  5. In the Joint microdialog or Property Editor, turn on Limits.

Plot Limit Forces

Limit force for translation forces or limit torque for rotational forces.

  1. After running a motion analysis, select the joint name in the Model Browser.
    A plot is displayed.
  2. Right-click the plot, and select Limits Force for translational forces due to limits or Limits Torque for rotational forces due to limits.

Impact Properties

When the limit is reached, methods are used to calculate impact forces. Impact properties control the behavior of the limit response.

Similar to motion contacts, the force and torque response due to the limit can be controlled by adjusting the impact properties in the Property Editor.
Note:
  • Depending on the application, setting the Integrator Tolerance to 1e-5 can provide better convergence.
  • A limit of 0 completely prevents movement in that direction. If only one direction of the limit needs to be represented, instead of leaving the other limit at 0, set it to a higher value that will never be reached and will not hinder motion in the non-limited direction.