How to change Solver's convergence/tolerance criteria

[Saman Nezami]

Hi,

Introduction: I am using Chrono for multi body dynamic simulation. I have been using the PSOR solver and the Euler implicit Initialized time integrator. These option are the default settings and relatively provides a high speed simulation among other available options in Chrono.

Problem definition: For a high magnitude of forces or impulses the constraint violation and force residuals increases and causes instability in the simulation. Since in the Chrono the solver uses a fixed time stepper, one solution to improve this issue can be using a smaller time step. However reducing the time step will increase the simulation time proportionally.

Question: Is there an alternative option such as adjusting the convergence criteria, force/constraint tolerance or force/constraint residuals?

Is there an example for this? 

Thanks,

- Saman

[SIMONE BENATTI]

Hi Saman,

you should try Barzilai-Borwein (as in demo_VEH_TrackedJSON.cpp) or the more recent ADMM.

Solver options might be set either from the solver itself (see demo_FEA_ancfShell_8.cpp) of from the system (see demo_CAS_robot.cpp)

Simone