I'm trying to get internal forces in a rigidBodyTree.
Suppose that I have simple robot with one joint, which I can generate with this code:
robot = rigidBodyTree('DataFormat', 'row');
robot.Gravity = [0 0 9.81];
body1 = rigidBody('body1');
body1.Mass = 1;
jnt1 = rigidBodyJoint('jnt1','revolute');
setFixedTransform(jnt1,[1 0 0 0],'dh');
body1.Joint = jnt1;
This robot has a joint with an axis pointing in the Z direction. And when I run inverseDynamics(robot) the resulting joint torque required to hold the weight of the body is 0, as expected because the axis of the joint point in the same direction as gravity.
But, the torque is still there, it would still need to be held by bearings for example. Is there a way to get the internal forces and torques? It seems to me that they are being calculated in order to get the requred joint torques in the inverseDynamics function. I just can't find a way to get them out.