[Question] Self-Collision Penalty

[Evm7]

Question

When running the default examples for locomotion, like RoughEnvCfg for Digit, there is a reward defined as undesired_contacts.

Let's imagine we set this reward to penalize anything that's not the feet for getting in contact with the floor. One could do something like this (for G1):

  undesired_contacts = RewTerm(
        func=mdp.undesired_contacts,
        weight=-1.0,
        params={"sensor_cfg": SceneEntityCfg("contact_forces", body_names=[r"^(?!left_ankle_roll_link)(?!right_ankle_roll_link).+$"]), "threshold": 1.0},
    )

However, this penalty does not differentiate the feet contacting the floor (desired) or the other foot (undesired). Is there a way to, for instance, to penalize only self-collision? Can we filter out the contact_forces with the floor?

[ooctipus]

to penalize self collision, you would need to set those contact sensor to filter against the ground, assume ground is the only object you filtered against and no other object exist, then you can get self collision force by subtracting net force to filtered force.

If you only want to filter against particular body, note that Many to Many filtration is impossible from physics engine level.