Simscape Multibody: Variable Stiffness in Revolute joint with motion as input

I wish to implement a revolute joint block that uses motion as input with a variable stiffness. However, for the revolute joint block, only scalar values are accepted for the stiffness parameter.

In this answer https://www.mathworks.com/matlabcentral/answers/401095-could-the-value-of-spring-stiffness-in-the-revolute-joint-block-simscape-be-variable a feedback loop is suggested. However, this is not possible with motion as input of the joint.

I tried manipulating the parameter in several ways but failed. Unlike with other simscape blocks, it is not possible to view the source code of simscape multibody blocks.

Is there any way to make this work?

[Abhinaba Basu]

Is there any solution to this? I too have the same issue

Answer 1

[Juan Sagarduy]

Hi Raphael

There is no simple way of doing this by remaining in kinematic mode (constrained motion).

 If you use the joint actuated dynamically, it will receive the driving torque to follow the angle prescribed.

 There will be a negative component resulting from the variable stiffness in a Simscape system fed by the sensed rotational speed.

Hope this helps Br Juan