Hi - if you share the model, we can give a better suggestion.
Your method of prescribing motion should work, though it is not the best way. When you use the du/dt block, you can run into numerical issues. We normally recommend either:
- Inputting the acceleration and integrating to get the velocity and position OR
- Inputting the position and letting Simscape calculate a consistent set of first and second derivatives for the motion. This will put a slight lag in your results, but if you make the filter constant very small the results should be quite close.
If you are not getting the answers you expect, first try one of these methods. You could also try reducing the maximum step size and tolerances and see if this improves the behavior of your model.