How do we properly set the coefficient of restitution in PyBullet?

[ErfanEtesami]

Hello.

I want to simulate the impact between objects in PyBullet. The "changeDynamics" function seems to provide the ability to define a coefficient of restitution for objects.

The restitution depends on the pair of objects, meaning that it is affected by their material, geometry, and even the impact velocity based on the experimental results.

The "changeDynamics" function allows for defining this coefficient (let us call it 'e') for each object separately. Therefore, I wonder if, for instance, I set this coefficient to 0.5 for object_a and to 0.2 for object_b, how PyBullet will interpret 'e' between these two objects? Is it going to multiply them together and assume the final restitution is 0.5*0.2=0.1? Furthermore, does it consider the contact type between two objects (the contact area, etc.)?

More generally, are there any helpful tips and hints about properly simulating the effect of impact in PyBullet?

Many thanks for your time and consideration.