Difference between SimOptions dt and RigidOptions dt with substeps!=1?

[Nate711]

What is the difference between SimOptions.dt and RigidOptions.dt when SimOptions.substeps is not 1? My simulation was crashing (all state variables like .get_pos() become NaN) when my robot contacted the ground at higher velocities (5m/s) with SimOptions(dt=0.02, substeps=20) and RigidOptions(dt=0.02) but no crashes with SimOptions(dt=0.001, substeps=1) and RigidOptions(dt=0.001). Surely this is a bug? Should RigidOptions.dt == SimOptions.dt/substeps?

[Nate711]

I'm still getting NaN when my robot contacts the ground after falling from 4m, even with dt=0.001. However, it wasn't an issue with rigidoptions.dt because I just had a bug where I wasn't doing enough sim steps to let the robot touch the floor at the lower dt setting.