Changed robot position between MuJoco v2 and v3 for same xml files #2262

jspieler · 2024-12-02T16:47:29Z

jspieler
Dec 2, 2024

Intro

Hi!

I am currently using MuJoCo to create an environment for a task similar to pick and place. The environment is based on the Gymnasium-robotics pick and place env.

My setup

Mujoco 2.1.0 / 3.1.6
Python API
Ubuntu 24

My question

While working with the Pick and Place env of Gymnasium robotics, I noticed that the robot position is quite far away from the table, which is only true if I use Mujoco 3.1.6, but is not the case for Mujoco 2.1.0. Also, the object position is different (on the floor instead of on the table). I checked the changes in the gymnasium-robotics versions, but for me it seems not like there were any changes. The xml files are also exactly the same for gymnasium-robotics. So I was wondering if the behavior was changed from version 2 to 3. I couldn't find any information on this. Would appreciate if someone could clarify it.

Minimal model and/or code that explain my question

If you encountered the issue in a complex model, please simplify it as much as possible (while still reproducing the issue).

Model:

pick_and_place.xml

<mujoco>
	<compiler angle="radian" coordinate="local" meshdir="../stls/fetch" texturedir="../textures"></compiler>
	<option timestep="0.002">
		<flag warmstart="enable"></flag>
	</option>

	<include file="shared.xml"></include>

	<worldbody>
		<geom name="floor0" pos="0.8 0.75 0" size="0.85 0.7 1" type="plane" condim="3" material="floor_mat"></geom>
		<body name="floor0" pos="0.8 0.75 0">
			<site name="target0" pos="0 0 0.5" size="0.02 0.02 0.02" rgba="1 0 0 1" type="sphere"></site>
		</body>

		<include file="robot.xml"></include>

		<body pos="1.3 0.75 0.2" name="table0">
			<geom size="0.25 0.35 0.2" type="box" mass="2000" material="table_mat"></geom>
		</body>

		<body name="object0" pos="0.025 0.025 0.025">
			<joint name="object0:joint" type="free" damping="0.01"></joint>
			<geom size="0.025 0.025 0.025" type="box" condim="3" name="object0" material="block_mat" mass="2"></geom>
			<site name="object0" pos="0 0 0" size="0.02 0.02 0.02" rgba="1 0 0 1" type="sphere"></site>
		</body>

		<light directional="true" ambient="0.2 0.2 0.2" diffuse="0.8 0.8 0.8" specular="0.3 0.3 0.3" castshadow="false" pos="0 0 4" dir="0 0 -1" name="light0"></light>
	</worldbody>

	<actuator>
		<position ctrllimited="true" ctrlrange="0 0.2" joint="robot0:l_gripper_finger_joint" kp="30000" name="robot0:l_gripper_finger_joint" user="1"></position>
		<position ctrllimited="true" ctrlrange="0 0.2" joint="robot0:r_gripper_finger_joint" kp="30000" name="robot0:r_gripper_finger_joint" user="1"></position>
	</actuator>
</mujoco>

robot.xml

```XML

										<body childclass="robot0:fetchGripper" name="robot0:r_gripper_finger_link" pos="0 0.0159 0">
											<inertial diaginertia="0.1 0.1 0.1" mass="4" pos="-0.01 0 0"></inertial>
											<joint axis="0 1 0" name="robot0:r_gripper_finger_joint" range="0 0.05"></joint>
											<geom pos="0 -0.008 0" size="0.0385 0.007 0.0135" type="box" name="robot0:r_gripper_finger_link" material="robot0:gripper_finger_mat" condim="4" friction="1 0.05 0.01"></geom>
										</body>
										<body childclass="robot0:fetchGripper" name="robot0:l_gripper_finger_link" pos="0 -0.0159 0">
											<inertial diaginertia="0.1 0.1 0.1" mass="4" pos="-0.01 0 0"></inertial>
											<joint axis="0 -1 0" name="robot0:l_gripper_finger_joint" range="0 0.05"></joint>
											<geom pos="0 0.008 0" size="0.0385 0.007 0.0135" type="box" name="robot0:l_gripper_finger_link" material="robot0:gripper_finger_mat" condim="4" friction="1 0.05 0.01"></geom>
										</body>
										<site name="robot0:grip" pos="0.02 0 0" rgba="0 0 0 0" size="0.02 0.02 0.02"></site>
									</body>
								</body>
							</body>
						</body>
					</body>
				</body>
			</body>
		</body>
	</body>
	<body name="robot0:estop_link" pos="-0.1246 0.2389 0.3113" quat="0.7071 0.7071 0 0">
		<inertial diaginertia="0 0 0" mass="0.002" pos="0.0024 -0.0033 0.0067" quat="0.3774 -0.1814 0.1375 0.8977"></inertial>
		<geom mesh="robot0:estop_link" rgba="0.8 0 0 1" name="robot0:estop_link"></geom>
	</body>
	<body name="robot0:laser_link" pos="0.235 0 0.2878" quat="0 1 0 0">
		<inertial diaginertia="0 0 0" mass="0.0083" pos="-0.0306 0.0007 0.0552" quat="0.5878 0.5378 -0.4578 0.3945"></inertial>
		<geom mesh="robot0:laser_link" rgba="0.7922 0.8196 0.9333 1" name="robot0:laser_link"></geom>
		<camera euler="1.55 -1.55 3.14" fovy="25" name="lidar" pos="0 0 0.02"></camera>
	</body>
	<body name="robot0:torso_fixed_link" pos="-0.0869 0 0.3774">
		<inertial diaginertia="0.3865 0.3394 0.1009" mass="13.2775" pos="-0.0722 0.0057 0.2656" quat="0.9995 0.0249 0.0177 0.011"></inertial>
		<geom mesh="robot0:torso_fixed_link" name="robot0:torso_fixed_link" class="robot0:blue"></geom>
	</body>
	<body name="robot0:external_camera_body_0" pos="0 0 0">
		<camera euler="0 0.75 1.57" fovy="43.3" name="external_camera_0" pos="1.3 0 1.2"></camera>
	</body>
</body>

```

Code:

import gymnasium as gym

import gymnasium_robotics


MUJOCO = "v2"
try:
    import mujoco_py
except ImportError:
    MUJOCO = "v3"

if MUJOCO == "v2":
    from gymnasium_robotics import register_robotics_envs
    register_robotics_envs()
    env_name = 'FetchPickAndPlaceDense-v2'

elif MUJOCO == "v3":
    gym.register_envs(gymnasium_robotics)
    env_name = 'FetchPickAndPlaceDense-v3'
else:
    raise NotImplementedError("Invalid Mujoco version")


if __name__ == "__main__":
    env = gym.make(env_name, max_episode_steps=150, render_mode="human")
    env.reset()

    for step in range(1000):
        action = env.action_space.sample()
        observation, reward, terminated, truncated, info = env.step(action)

        if terminated or truncated:
            env.reset()

Confirmations

I searched the latest documentation thoroughly before posting.
I searched previous Issues and Discussions, I am certain this has not been raised before.

Provide feedback

Saved searches

Use saved searches to filter your results more quickly

Changed robot position between MuJoco v2 and v3 for same xml files #2262

{{title}}

{{editor}}'s edit

{{editor}}'s edit

Replies: 0 comments

Select a reply

Changed robot position between MuJoco v2 and v3 for same xml files #2262

jspieler Dec 2, 2024

Intro

My setup

My question

Minimal model and/or code that explain my question

Confirmations

Replies: 0 comments

jspieler
Dec 2, 2024