How to tilt torso without moving leg #2116

dkhor2003 · 2024-10-03T18:37:44Z

dkhor2003
Oct 3, 2024

Intro

Hi!

I am a beginner using MuJoCo to do research on robotics.

My setup

<visual>
    <headlight ambient="0.5 0.5 0.5"/>
    <global offwidth="2560" offheight="1440" elevation="-20" azimuth="120"/>
</visual>

<option timestep="0.001" integrator="RK4" gravity="0 0 -9.81">
	<flag contact="enable" energy="enable"/>
</option>

<worldbody>
    <body name="ground" pos="0 0 0">
        <geom type="plane" material="MatPlane" size="10 10 0.1"/>
    </body>

    <body name="torso" pos="0 0 1">
        <geom type="box" size="0.1 0.2 0.1" rgba="0.3 0.6 1 1"/>
        <inertial pos="0 0 0" mass="10" diaginertia="0.1 0.1 0.1"/>
        <joint name="forward-backward" type="slide" axis="1 0 0"/>
        <joint name="left-right" type="slide" axis="0 1 0"/>
        <joint name="up-down" type="slide" axis="0 0 1"/>
        <joint name="tilt-left-right" type="hinge" axis="1 0 0" range="-0.7 0.7"/>
        <joint name="tilt-front-back" type="hinge" axis="0 1 0" range="-0.7 0.7"/>
        <body name="leg" pos="0 0 -0.1"> 
            <joint name="swing-left-right" type="hinge" pos="0 0 0.1" axis="1 0 0" actuatorfrcrange="-0.7 0.7"/>
			<joint name="swing-front-back" type="hinge" pos="0 0 0.1" axis="0 1 0" actuatorfrcrange="-0.7 0.7"/>
            <inertial pos="0 0 0" mass="0.001" diaginertia="0.001 0.001 0.001"/>
            <geom type="capsule" size="0.05 0.5" fromto="0 0 0 0 0 -0.85" rgba="1 0 0 1"/>
        </body>
    </body>
</worldbody>

<actuator>
	<motor ctrllimited="true" ctrlrange="-2.0 2.0" gear="20" joint="swing-left-right"/>
	<motor ctrllimited="true" ctrlrange="-2.0 2.0" gear="20" joint="swing-front-back"/>
</actuator>

My question

Hi,

I wanted tilt my torso front and back, and left and right. However, whenever I change the qpos value for the index 3 and 4 joints, the leg body changes as well. Is there any part in my xml file that I should change such that whenever I change qpos for the hinge joints of the torso, only the torso tilts, but not the leg. Also, whenever I change the qpos for the slide joints for the slide joints of the torso, the leg changes along with the torso.

Thanks,
Dylan.

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:

minimal XML

<mujoco>
  <worldbody>
    <light pos="0 0 1"/>
    <geom type="sphere" size="1" rgba="1 0 0 1"/>
  </worldbody>
</mujoco>

Code:

import mujoco
import mediapy as media
model = mujoco.MjModel.from_xml_string(xml)
data = mujoco.MjData(model)

with mujoco.Renderer(model) as renderer:
  mujoco.mj_forward(model, data)
  renderer.update_scene(data)

  media.show_image(renderer.render())

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How to tilt torso without moving leg #2116

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How to tilt torso without moving leg #2116

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dkhor2003 Oct 3, 2024

Intro

My setup

My question

Minimal model and/or code that explain my question

Confirmations

Replies: 0 comments

dkhor2003
Oct 3, 2024