Unitree Go2 SDK

A ROS 2 package that provides SLAM (Simultaneous Localization and Mapping) capabilities for the Unitree Go2 robot using an RPLiDAR sensor, the SLAM Toolbox and the Nav2 stack.

Overview

This package integrates:

• RPLiDAR for laser scanning
• SLAM Toolbox for mapping and localization
• Nav2 for autonomous navigation
• Transform broadcasting for robot pose integration
• RViz visualization for real-time monitoring

Features

• Real-time SLAM: Simultaneous localization and mapping using SLAM Toolbox
• RPLiDAR Integration: Support for RPLiDAR A1/A2/A3 series sensors
• Navigation: Integration with Nav2 for autonomous navigation
• Robot Control: Direct integration with Unitree Go2 movement commands
• Visualization: Pre-configured RViz setup for monitoring
• Transform Management: Automatic handling of coordinate frame transforms

Prerequisites

• ROS 2 Humble
• Python 3.10+
• RPLiDAR connected via USB (typically /dev/ttyUSB0)

Installation

0. Hardware setup:

We provide two options for placing the RPLiDAR on the Unitree Go2 robot:

• Option 1: Mount the RPLiDAR on the head of the robot using a 3D-printed mount.

  

• Option 2: Mount the RPLidar at the center of the robot using a 3D-printed mount.

  

You can find the 3D model for the mount in the models directory of this repository.

1. Clone this repository into your ROS 2 workspace:

cd ~/ros2_ws/src
git clone https://github.com/OpenmindAGI/unitree_go2_ros2_sdk.git

2. Install dependencies:

cd ~/ros2_ws
rosdep install --from-paths . --ignore-src -r -y

3. Install Python dependencies:

pip install -r requirements.txt

4. Build the packages:

colcon build --packages-select unitree_api unitree_go go2_sdk

5. Source the workspace:

source install/setup.bash

6. Set up RPLiDAR permissions:

# Option 1: Temporary permission (needs to be run each time)
sudo chmod 777 /dev/ttyUSB0

# Option 2: Add user to dialout group (permanent, requires logout/login)
sudo usermod -a -G dialout $USER

# Option 3: Create udev rule (permanent)
echo 'KERNEL=="ttyUSB*", ATTRS{idVendor}=="10c4", ATTRS{idProduct}=="ea60", GROUP="dialout", MODE="0666"' | sudo tee /etc/udev/rules.d/99-rplidar.rules
sudo udevadm control --reload-rules && sudo udevadm trigger

Usage

Launch SLAM System

To start the complete SLAM system:

ros2 launch go2_sdk slam_launch.py

Once you have done the mapping, you can save the map through the RViz2 interface by clicking on the Save Map button and the Serialize Map button in the SlamToolboxPlugin panel.

Launch Navigation System

To start the navigation system with SLAM:

ros2 launch go2_sdk nav2_launch.py map_yaml_file:=<path_to_your_map_yaml_file>

Control the Robot

Once SLAM is running, you can control the robot using:

# Using keyboard teleop (install first: sudo apt install ros-humble-teleop-twist-keyboard)
ros2 run teleop_twist_keyboard teleop_twist_keyboard

# Or publish velocity commands directly
ros2 topic pub /cmd_vel geometry_msgs/Twist '{linear: {x: 0.5, y: 0.0, z: 0.0}, angular: {x: 0.0, y: 0.0, z: 0.0}}'

Or use an Xbox controller to control the robot

Note

For the Xbox controller, the RB button is the enable/disable button. Different Xbox controllers may have different button mappings, so you may need to adjust the launch files accordingly.

REST API

The Go2 SDK provides a REST API for remote control and monitoring of the robot. The API server runs on port 5000 and provides the following endpoints:

API Endpoints

GET /api/status

• Returns the API status
• Response: {"status": "OK", "message": "Go2 API is running"}

GET /api/pose

• Returns the current robot pose with covariance
• Response:

{
  "position": {"x": 0.0, "y": 0.0, "z": 0.0},
  "orientation": {"x": 0.0, "y": 0.0, "z": 0.0, "w": 1.0},
  "covariance": [...]
}

POST /api/move_to_pose

• Sends the robot to a specific pose
• Request body:

{
  "position": {"x": 1.0, "y": 2.0, "z": 0.0},
  "orientation": {"x": 0.0, "y": 0.0, "z": 0.0, "w": 1.0}
}

• Response: {"status": "success", "message": "Moving to specified pose"}

GET /api/amcl_variance

• Returns AMCL localization uncertainty
• Response:

{
  "x_uncertainty": 0.1,
  "y_uncertainty": 0.1,
  "yaw_uncertainty": 5.0
}

GET /api/nav2_status

• Returns the status of active navigation goals
• Response:

{
  "nav2_status": [
    {
      "goal_id": "abc123...",
      "status": "EXECUTING",
      "timestamp": {"sec": 1234567890, "nanosec": 123456789}
    }
  ]
}

GET /api/map

• Returns the current occupancy grid map
• Response:

{
  "map_metadata": {
    "map_load_time": {"sec": 1234567890, "nanosec": 123456789},
    "resolution": 0.05,
    "width": 384,
    "height": 384,
    "origin": {
      "position": {"x": -10.0, "y": -10.0, "z": 0.0},
      "orientation": {"x": 0.0, "y": 0.0, "z": 0.0, "w": 1.0}
    }
  },
  "data": [0, 0, 0, ...]
}

Visualize in RViz

Launch RViz with the provided configuration:

rviz2 -d config/rviz.rviz

Run Zenoh Ros2 Bridge

To run the Zenoh bridge for the Unitree Go2, you need to have the Zenoh ROS 2 bridge installed. You can find the installation instructions in the Zenoh ROS 2 Bridge documentation

After installing the Zenoh ROS 2 bridge, you can run it with the following command:

zenoh-bridge-ros2dds -c ./zenoh/zenoh_bridge_config.json5

Troubleshooting

RPLiDAR Connection Issues

1. Check USB connection:

ls -la /dev/ttyUSB*

2. Verify permissions:

sudo chmod 777 /dev/ttyUSB0

3. Add user to dialout group:

sudo usermod -a -G dialout $USER

SLAM Performance Issues

• Reduce scan_buffer_size if experiencing dropped messages
• Adjust correlation_search_space_dimension for better loop closure
• Modify loop_search_maximum_distance based on environment size

Transform Issues

• Ensure all required transforms are being published
• Check TF tree with: ros2 run tf2_tools view_frames
• Verify timing with: ros2 topic echo /tf

Robot Control Issues

• Verify cmd_vel messages are being published: ros2 topic echo /cmd_vel
• Ensure the robot is in the correct mode for receiving movement commands

Timestamp Issues

The ROS topic timestamps from the Unitree Go2 are 12 seconds behind the current system time. Please disable your computer’s Automatic Date & Time setting and manually sync the timestamp using:

sudo date -s "@unix"

You can find the timestamp from the Unitree Go2 by running:

ros2 topic echo /utlidar/robot_pose --field header.stamp

If the Linux machine has an internet connection, you can share the inet connection with the Unitree Go2 robot to automatically sync the time.

sudo nmcli connection add type ethernet ifname enp112s0 con-name ethernet-shared
sudo nmcli connection modify ethernet-shared ipv4.method shared
sudo nmcli connection modify ethernet-shared ipv4.addresses 192.168.123.1/24
sudo nmcli connection up ethernet-shared

and you can verify the shared connection with:

nmcli connection show ethernet-shared