Using Manikin Constraints  

The commands in the Manikin Constraints toolbar give you the capability to constrain the manikin in its environment. With constraints, the manikin can perform inverse kinematics (IK) to calculate the necessary posture needed to reach multiple specific targets.
  The following constraint topics are discussed in this task:
A constraint will always belong to one manikin. At any given time, the list of constraints on a manikin will appear underneath that manikin in the specification tree. Inactive constraints will also be listed.

At any time, you may update the active constraints at each modification in the workspace (automatic update), or only update the active constraints when needed (manual update). 

By default, constraint update mode is set in the Manual mode and you must select Update in the Update toolbar each time you want to update the active constraints and resolve the inverse kinematics. 

In Automatic mode, the inverse kinematics will react as soon as the configuration of the environment changes; when the objects move, the inverse kinematics updates in real time.

General options

As shown in the image below, you can change the update mode at any time by selecting Tools > Options > Ergonomics Design & Analysis > Human Builder. The Manual and Automatic update options are available in the General tab under the Constraint Resolution heading.

 

Display options

By default, when constraints are displayed, the following colors, and line type and thickness indicate the current state of the constraint. Change the defaults in the Display tab of Tools > Options > Ergonomics Design & Analysis > Human Builder.

 

Creating constraints

From the samples directory, open:
 

 

  1. For this procedure the constraint update mode is set at the default Manual mode.

  2. Select one of the constraint commands from the Manikin Constraint toolbar and then select a manikin segment for a Fix (constraint) and the object (for other constraints).

  3. For more information on each constraint type, please see:
     

Contact Constraint
Coincidence Constraint
Fix Constraint
Fix On Constraint
 

Updating constraints

 
  1. Select Update to resolve the active IK constraints. The constraints and normal vectors are now green indicating that they are resolved.


     

  2. Move the box again so that the constraints go to an unresolved state.

  3. In the 3D viewer, the colors for the normal vector and the unresolved constraints have changed accordingly.

  4. Change the defaults in the Display tab of Tools > Options > Ergonomics Design & Analysis > Human Builder.

  5. Update the constraints again. The resolved constraints are the new color.


     

  6. Verify that the new unresolved constraint color is applied. Move the manikin so that the constraints become unresolved and the color changes.

 

Constraints and simulations

Permanent constraints are automatically disabled when a simulation is run to avoid conflicts with constraints created in MoveToPosture activities. When the Process Simulation command is selected, the constraint icon in the PPR tree changes, as shown below to indicate that the constraint is no longer active.

When you wish to enable the constraint after the simulation is finished, in the PPR tree, right-click on the constraint. Re-activate that constraint through the contextual menu that appears.

The constraint icon in the PPR tree changes to reflect that it is again activated.

  For more information about the specific types of constraints, please read:
Contact Constraint
Coincidence Constraint
Fix Constraint
Fix On Constraint