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()

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

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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