Isaacgym collision model penetration

Hello, I am using ‘Legged Gym,’ which is a derivative of ‘Isaac Gym.’ During my usage, I encountered an issue related to the collision model that I find difficult to comprehend.

As depicted in the accompanying video, the collision model in the URDF file seems to be penetrating the plane. I would greatly appreciate any guidance or suggestions on how to resolve this problem.

After careful consideration, I believe that the issue might be connected to the ankle joint, although pinpointing the exact underlying cause is proving challenging.

In the URDF file, ground penetration occurs when the ankle joint is set to revolute, whereas no penetration occurs when it is fixed.

Additionally, I have observed that other URDF files like ‘Cassie’ or ‘AnYmal’ do not exhibit ground penetration. The URDF file where the penetration occurs was based on a ‘Cassie’ model.

I would highly appreciate any comments or ideas that you may have regarding this matter.