Domain randomization code creates issue with robot collisions

[RobertMcCarthy97]

Hi,

I was using your domain randomization implementation for my RRC 2021 submission and found it very useful, thanks.

Just to let you know:

I came across an issue here, where randomizing the 'contact stiffness' and 'contact damping' somehow removes the collision properties of the robot arms in simulation i.e., the arms can pass through each other (the arm tips remain normal though).

My temporary solution was to just comment out lines 16 and 17 of the linked file.