cybermax
mrice:
it is very strange that Your system dont have any instability. If the constraint is under big pressure(heavy object(s)), it is unstable. A similar problem I had with ODE, but instability created much earlier.
It depends on what you consider instability. I'd say that's the nature of using an iterative constraint solver, probably made worse by single-precision math. I haven't seen any change in behavior caused by simulating a large number of constraints though. The general “solution” would be to do more iterations and/or simulate a smaller timestep. Simplifying mass distribution and inertia tensors might also help. And the easiest thing to do is to only simulate objects which need to be simulated..