Berkeley Humanoid Lite Assets

This repository contains the assets files and tools necessary for working with the Berkeley Humanoid Lite model. It includes scripts for generating URDF files from Onshape and converting them to MJCF and USD formats to use in multiple simulators.

Generate description file from Onshape

To export the Onshape design as URDF/MJCF file, we will be using the onshape-to-robot tool.

First, we need to install the necessary system dependencies:

sudo apt install openscad meshlab

Then, run the corresponding export script:

For URDF:

uv run ./scripts/export_onshape_to_urdf.py --config ./data/robots/berkeley_humanoid/berkeley_humanoid_lite/urdf/config.json

For MJCF

uv run ./scripts/export_onshape_to_mjcf.py --config ./data/robots/berkeley_humanoid/berkeley_humanoid_lite/mjcf/config.json

Note

Before running the script, make sure that the robot in the OnShape project is configured correctly, and all joints are at reset position.

The resulting URDF will be generated at /data/robots/berkeley_humanoid/berkeley_humanoid_lite/urdf/, MJCF will be generated at /data/robots/berkeley_humanoid/berkeley_humanoid_lite/mjcf/, and the STL meshes will be shared under /data/robots/berkeley_humanoid/berkeley_humanoid_lite/meshes/.

Cleaning onshape-to-robot cache

Run the following command to clear the CAD file cache.

onshape-to-robot-clear-cache

Convert URDF to USD

To generate USD file from URDF file, simply run the following command.

uv run ./scripts/convert_urdf_to_usd.py ./data/robots/berkeley_humanoid/berkeley_humanoid_lite/urdf/berkeley_humanoid_lite.urdf 

Axis Convention

We follow the ROS REP-0103 standard for the frame and axis convention.

The forward direction of the robot is positive X axis, and the left direction is positive Y axis. The robot is standing still on a flat surface, with the Z axis pointing upwards.

The joint axis are defined to be pointing in the same direction as the robot's reference frame.

Degree of Freedoms

Joint ID	Name	CAN ID	Range	Description
Left Arm
0	arm_left_shoulder_pitch_joint	1	[-90, 45]	controls the flexion/extension (pitch) motion of the left upper arm. Positive is flexion
1	arm_left_shoulder_roll_joint	3	[0, 90]	controls the abduction/adduction (yaw) motion of the left upper arm. Positive is adduction
2	arm_left_shoulder_yaw_joint	5	[-45, 45]	controls the rotation (roll) motion of the left upper arm. Positive is lateral rotation
3	arm_left_elbow_pitch_joint	7	[-90, 0]	controls the flexion/extension (pitch) motion of the left forearm. Positive is extension
4	arm_left_elbow_roll_joint	9	[-45, 45]	controls the rotation (roll) motion of the left forearm. Positive is lateral rotation
Right Arm
5	arm_right_shoulder_pitch_joint	2	[-45, 90]	controls the flexion/extension (pitch) motion of the right upper arm. Positive is extension
6	arm_right_shoulder_roll_joint	4	[-90, 0]	controls the abduction/adduction (yaw) motion of the right upper arm. Positive is abduction
7	arm_right_shoulder_yaw_joint	6	[-45, 45]	controls the rotation (roll) motion of the right upper arm. Positive is medial rotation
8	arm_right_elbow_pitch_joint	8	[-90, 0]	controls the flexion/extension (pitch) motion of the right forearm. Positive is flexion
9	arm_right_elbow_roll_joint	10	[-45, 45]	controls the rotation (roll) motion of the right forearm. Positive is medial rotation
Left Leg
10	leg_left_hip_roll_joint	1	[-10, 90]	controls the flexion/extension (pitch) motion of the left thigh. Positive is flexion
11	leg_left_hip_yaw_joint	3	[-33.75, 56.25]	controls the abduction/adduction (yaw) motion of the left thigh. Positive is adduction
12	leg_left_hip_pitch_joint	5	[-108.75, 56.25]	controls the rotation (roll) motion of the left thigh. Positive is lateral rotation
13	leg_left_knee_pitch_joint	7	[0, 140]	controls the flexion/extension (pitch) motion of the left shin. Positive is extension
14	leg_left_ankle_pitch_joint	11	[-45, 45]	controls the rotation (roll) motion of the left shin. Positive is lateral rotation
15	leg_left_ankle_roll_joint	13	[-15, 15]	controls the inversion / eversion (roll) motion of the left foot. Positive is eversion
Right Leg
16	leg_right_hip_roll_joint	2	[-90, 10]	controls the flexion/extension (pitch) motion of the right thigh. Positive is extension
17	leg_right_hip_yaw_joint	4	[-56.25, 33.75]	controls the abduction/adduction (yaw) motion of the right thigh. Positive is abduction
18	leg_right_hip_pitch_joint	6	[-56.25, 108.75]	controls the rotation (roll) motion of the right thigh. Positive is medial rotation
19	leg_right_knee_pitch_joint	8	[0, 140]	controls the flexion/extension (pitch) motion of the right shin. Positive is flexion
20	leg_right_ankle_pitch_joint	12	[-45, 45]	controls the rotation (roll) motion of the right shin. Positive is medial rotation
21	leg_right_ankle_roll_joint	14	[-15, 15]	controls the inversion / eversion (roll) motion of the right foot. Positive is inversion

Info

The descriptions are based from this reference.