Can add_fix_point_constraint simulate parallel mechanisms？

[lanyu35]

Hi, thank you for your excellent work on this project!

I’m currently working on simulating an underactuated claw gripper, like those used in claw machines. The gripper consists of multiple rigid links that are mechanically coupled, forming a parallel structure. Specifically, there are three pairs of contact points between different bodies that need to stay coincident throughout the motion.

I came across the add_fix_point_constraint function, which seems to "weld" two bodies together at a point.

I’m wondering whether this function can be used to model parallel mechanisms, where multiple bodies are passively linked and must maintain alignment at multiple contact points—similar to MuJoCo’s equality constraint.

Thanks a lot for your help and clarification!