Incorrect rendering of goal spheres in `reach-v2` tasks

[jwbirkbeck]

Hi All,

I'm raising this for the reach-v2 environment but it might apply to other tasks.

When rendering all the available tasks using the below code, the red sphere does not change position. This leads users to mistakenly conclude the target position is the same across tasks.

I believe this is because the reset_model method only updates self._target_pos which has no impact on the rendering within MuJoCo. The reward function is therefore correct across tasks, but the rendering is incorrect.

If this is correct, a likely fix is to add the a line to the end of the reset_model method:

self._set_pos_site('goal', self._target_pos)

As a related issue, the potential confusion is made worse due to the goal parameter being a fixed constant (from the init, self.goal = np.array([-0.1, 0.8, 0.2])). Under 'least surprise' I think self.goal should provide the user with the same information as self._target_pos.

import metaworld

ml1 = metaworld.ML1('reach-v2')
env = ml1.train_classes['reach-v2'](render_mode='human')

while True:
    for task in ml1.train_tasks:
        env.set_task(task)
        env.reset()

[emlynw]

Hi,

Thanks for posting this, I was using the push-v2 environment and didn't realize that the sphere was meant to move.

I tried adding self._set_pos_site('goal', self._target_pos) to the reset_model method but the sphere still didn't move between episodes. Adding it to the evaluate_state method seems to work though

[Kallinteris-Andreas]

what mujoco version are you running?

[emlynw]

2.3.7

[reginald-mclean]

This is definitely something to look into, I will try and look into it tomorrow or over the weekend

Reginald McLean (he/him) Ph.D. Candidate, Department of Computer Science Lead Maintainer of Meta-World https://github.com/Farama-Foundation/Metaworld/ Toronto Metropolitan University https://www.torontomu.ca/ (formerly Ryerson University)

On Wed, Apr 17, 2024 at 1:53 PM Emlyn @.***> wrote:

2.3.7

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[reginald-mclean]

Hi @emlynw and @jwbirkbeck thanks for letting us know about this issue. I am going to ask you to test the environments that you are using by making a slight modification to the reset function in sawyer_xyz_env.py in metaworld/envs/mujoco/sawyer_xyz/. It should look like this after adding one line:

def reset(self, seed=None, options=None): self.curr_path_length = 0 obs, info = super().reset() self.model.site('goal').pos = self._target_pos mujoco.mj_forward(self.model, self.data) self._prev_obs = obs[:18].copy() obs[18:36] = self._prev_obs obs = np.float64(obs) return obs, info

[emlynw]

Works for me in push-v2, thanks!

[emlynw]

Adding self.model.site('goal').pos = self._target_pos into sawyer_xyz_env.py causes issues with other environments that don't have a 'goal' key such as the coffee environments. As @jwbirkbeck said adding it into the reset_model of the specific environment's method works, and this doesn't affect the other environments

[reginald-mclean]

Ah yep, the goal is different. The following list of environments will pass with that fix:

['basketball-v2', 'box-close-v2', 'dial-turn-v2', 'door-close-v2', 'door-open-v2', 'hand-insert-v2', 'drawer-close-v2', 'drawer-open-v2', 'hammer-v2', 'lever-pull-v2', 'peg-insert-side-v2', 'pick-place-wall-v2', 'pick-out-of-hole-v2', 'reach-v2', 'push-back-v2', 'push-v2', 'pick-place-v2', 'plate-slide-v2', 'plate-slide-side-v2', 'plate-slide-back-v2', 'plate-slide-back-side-v2', 'peg-unplug-side-v2', 'soccer-v2', 'stick-push-v2', 'stick-pull-v2', 'push-wall-v2', 'reach-wall-v2', 'shelf-place-v2', 'sweep-into-v2', 'sweep-v2', 'window-open-v2', 'window-close-v2']

[reginald-mclean]

This is going to be fixed by PR #473