Robot body object property

[Thomas]

Also, with same dynamic property setting, pure shape and non-pure shape work differently.
What is this?

[coppelia]

Yes, they are handled differently by the various physics engines. For instance:

• A pure sphere can be seen as a point with radius. Computing contact points and forces between a pure sphere and an other object is much simpler/faster.
• A non-pure sphere can be seen as a collection of triangles, or a mesh. Computing contact points and forces is more complex and slower. But since the sphere is convex, some specialized routines can be used
• a non-pure sphere with a hole in it can be seen as a collection of random triangles. Computing contact points and forces is much more complex, less precise and slower.

Cheers