Get the external forces acting against a Joint of an ArticulationBody

Unity Engine
,
1

Hello everyone,

In my scene I have an ArticulationBody setup in a hierarchy of three GameObjects, each one part of the ArticulationBody with its own Joint defined as a part of the ArticulationBody.

It looks like this:

  • Articulationbody (Root body of the articulation)
  • Articulationbody (Joint type: Fixed)
  • Articulationbody (Joint type: Spherical)

I am applying different forces to the last Joint (Spherical joint with full freedom and no axis locked) and I would like to know the forces acting under this Spherical Joint.

I understood from the documentation that this is possible thanks to the method ArticulationBody.GetJointExternalForces but I am struggling to get this information.

I have identified the Index of my ArticulationBody through Articulationbody.Index and I think I have to use also:

ArticulationBody.GetDofStartIndices

, but honestly I think I am not understanding correctly the documentation.

When I call:

ArticulationReducedSpace space = myArticulationBody.jointForce;
Debug.Log("Reduced Space 0: " + space[1]);

I can read always Zero for the 3 degrees of freedom of my spherical joint placed on the last element of the hierarchy.

Could someone please give me a bit of clarity on how to achieve this or how to correctly use these methods?

Many thanks and happy coding everyone
Pablo