Why Were the Tendons on `Humanoid`'s models removed (hip knees)?

[Kallinteris-Andreas]

The original gymnasium Humanoid had 2 tendons: https://github.com/Farama-Foundation/Gymnasium/blob/2feeb31378942ff3373915a4fe31faffb0d2b26c/gymnasium/envs/mujoco/assets/humanoid.xml#L91

Which are not present in the brax model

https://github.com/google/brax/blob/c2cd14cf762242d63aeec106d955390c8e14d582/brax/envs/assets/humanoid.xml

Is there a reason for that?

Note: HumanoidStandup has the tendons https://github.com/google/brax/blob/c2cd14cf762242d63aeec106d955390c8e14d582/brax/envs/assets/humanoidstandup.xml

[btaba]

Hi @Kallinteris-Andreas , thanks for using brax! As of now brax does not support tendons. We should add an error if tendons are present and remove them on humanoidstandup

[Kallinteris-Andreas]

Is there an approximate ETA for tendon support? Is it on the roadmap?

[btaba]

Hi @Kallinteris-Andreas it's not really on the roadmap or high priority, but if you'd like to take a stab please feel free!