My original intention is to use rotation to correct the workpiece, but why the rotation of the physical joint is appropriate at first, but it does not revolve around the axis of rotation later
your uploaded Videos arn’t working?!
Are the physics entity behaviors of those joints set to be In Physics or Kinematic? And how tight is the coupling? Would need to have layout to help. Generally, what is shown in your video happens because too much force breaks things and the pivot point of entity changes or it is a nuance with the D6Joint itself in which using Z-axis or twist axis and orientation of the joint that scrambles things.