joint velocity limit causes significant jitter (as shown in Sandia Hand example)

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Issue #634 open
John Hsu created an issue

see this ticket on Sandia hand, it turns out the limiting mechanism yields jittery joint velocity. We should think of a better limiting mechanism.

Comments (9)

  1. Jesper Smith

    Copied form the ticket on the Sandia Hand:

    Maybe a better implementation would be to use a penalty function instead of setting the effort to zero at the velocity limit. For example,

    if ( velocity > maxVelocity)
    {
         damping =  - Kv * (velocity - maxVelocity);
         effort = effort + damping;
    }
    else ( velocity < -maxVelocity)
    {
         damping =  - Kv * (velocity - -maxVelocity);
         effort = effort + damping;
    }
    

    Where Kv is a tuned limit gain. However, if the measured joint velocity is non-zero when the fingers are stationary and in contact with an object any velocity limit will probably lead to instability or lower than desired torques.

  2. Jesper Smith

    Have not tested the patch, however disabling the limits worked for us. Therefore, non-blocker for VRC for our team

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