How to simulat the contact between environment and a part of the robot?

[Hacher]

I'm trying to simulate the contact between the wheels of a mobile robot and the ground level so I have make the robot responsible and dynamically, but that may cause strange movement of the robot and the parts will move freely because there are many small irregular shapes of the shaft and holes of the robot parts,(it is generated by convex decomposition).I had tried to make all parts except wheels non-dynamically, but that will still make wheels move freely, and I think that may cause the force cannot be pass to whole robot from the wheel. Can you help me to fix this problem? Thank you very much.

[Hacher]

This have been solved, on need bother. Thank you.