Longsen Gao

Full-stack in Robotics ∩ Control ∩ Deep Learning

2 minute read

How do you get any placement position and rotation on MuJoCo quickly?

When I build up a new MuJoCo environment or need to modify the environment based on the previous environment, especially I want to insert a new body or geom with a precise position and rotation , sometimes it’s difficult because of the complexity of the high-DoF model and waste me lots of time:persevere:. Here you can use the tool I support here to help you find your desired placement in quick.

Preparations: Please refer the mujoco-py setup in my previous blog through this link to install related dependencies.

How to use:

  1. Add these code blocks on your own MuJoCo xml file:

    • Add below on <worldbody>…</worldbody>:
        <body name="endeff_des" pos="0 0 0" mocap="true">
        <geom type="sphere" size="0.015" rgba="1 0 0 1" />
        <geom class="x_s_axis"/>
        <geom class="y_s_axis"/>
        <geom class="z_s_axis"/>
    </body>
    • Add below on your </default>…</default>:
        <default class="x_s_axis">
        <geom contype="0" conaffinity="0" group="1" rgba="1 0 0 1"
              type="cylinder" size=".005 0.05" pos="0.05 0 0" euler="0 1.570796327 0"/>
    </default>
    <default class="y_s_axis">
        <geom contype="0" conaffinity="0" group="1" rgba="0 1 0 1"
              type="cylinder" size=".005 0.05" pos="0 0.05 0" euler="1.570796327 0 0"/>
    </default>
    <default class="z_s_axis">
        <geom contype="0" conaffinity="0" group="1" rgba="0 0 1 1"
              type="cylinder" size=".005 0.05" pos="0 0 0.05" euler="0 0 0"/>
    </default>

  2. Drag the Fast_Tune.py file in any location on your PC (suggested to put it on the same location of your MuJoCo xml file.)

  3. Change the two lines on the code with your own MuJoCo environment file and referred frame:

    ref_body_name = "satellite" # Change your refered frame
xml_test_name = "/home/wam/sat_demo.xml"  # Change your own environment file location

  4. Then run the file. You will see the scenario like the following:

You can use ← → ↑ ↓ F B on your keyboard to change the frame location; And Q/W, A/S, Z/X to change the row, pitch, yaw roation of the frame. You need to put the frame on your desired location and rotation. Then afterthat, record the data on the right-head dashboard as

Note that when the frame is moving, the data on this area is also changing. W-position means the position of moving frame relative to the world frame in X, Y, Z; B-position means the position of moving frame relative to your specific frame in X, Y, Z;n Similar to W-Rotation and B-Rotation. Based on this information, you can change your xml in a quick time.

Additionally, I also test in another project and find the effect is good.

Click the link to clone the project from Github.

If you can give me a star that this tool do help you for your project, I will be so happy. :two_hearts:

You May Also Enjoy