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I'm trying to torque control a revolute joint in Simscape multibody and while I am able to get my joint to rotate, it does not seem to properly output torque. I thought it was an inverse kinematics issue, though no error was thrown. What's more, when I input a torque directly, there is no motion of the revolute joint and though my scope shows a torque on the sensing output. Still no error is thrown.

I'm at a bit of a loss on how to troubleshoot this issue.. My hope was to implement some sort of torque controller on the joint, but this step is proving rather difficult to overcome because I really don't know where to dig any deeper.. Any help or thoughts would be appreciated.

Carson Lansdowne
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1 Answers1

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I have a similar model, where I am controlling a revolute joint by torque demand which is obtained by:

  1. Obtain setpoint from position demand vector in the workspace.
  2. Inverse kinematics to convert to joint space position demand
  3. PID control
  4. PID signals sent to a motor model built in simscape (where my friction parameters are also defined), which outputs a torque setpoint.
  5. Torque setpoint is then provided as an input to the joints.

One possible issue is that the internal mechanics of your joint may have damping which is too high, preventing movement.

Another possible issue is that The actuation of the joint may be misconfigured. My model works with Torque: None and Motion: Automatically Computed.

A snapshot of my joint parameters for a joint actuated by an extaernally provided torque

Ametcalf
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