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ROS2 Distributed Teleoperation

This tutorial explains how to set up a distributed teleoperation system using ROS2, allowing a leader robot on one computer to control a follower robot on another computer over a network.

Prerequisites

ROS2 (Foxy or newer) installed on both computers
Network connectivity between the leader and follower computers
lerobot package installed on both computers

Installation

Ensure you have the required ROS2 packages for sensor messages:

pip install sensor_msgs

Setup

1. Configure ROS2 Domain ID (optional but recommended)

To isolate your ROS2 network from others, set the same domain ID on both computers:

# On both leader and follower computers
export ROS_DOMAIN_ID=42  # Choose any number between 0-232

2. Network Configuration

Ensure both computers can communicate over the network:

Connect both computers to the same network
Verify they can ping each other
Make sure any firewalls allow ROS2 communication (default ports)

Running the Distributed Teleoperation

1. Leader Robot Computer

On the computer connected to the leader robot:

python lerobot/scripts/run_ros2_leader.py \
  --robot.type=koch \
  --robot.leader_arms.main.port=/dev/ttyUSB0 \
  --ros2_config.node_name=lerobot_teleop \
  --ros2_config.topic_name=joint_states \
  --ros2_config.publish_rate_hz=200.0

Replace /dev/ttyUSB0 with the actual port of your leader robot.

2. Follower Robot Computer

On the computer connected to the follower robot:

python lerobot/scripts/run_ros2_follower.py \
  --robot.type=koch \
  --robot.follower_arms.main.port=/dev/ttyUSB0 \
  --ros2_config.node_name=lerobot_teleop \
  --ros2_config.topic_name=joint_states

Replace /dev/ttyUSB0 with the actual port of your follower robot.

Note on Topic Names

Make sure both leader and follower use the same topic name (default is joint_states).

Troubleshooting

1. Check ROS2 Discovery

Verify nodes can discover each other:

# On either computer
ros2 topic list

You should see /joint_states in the list.

2. Monitor Message Flow

Check if messages are being published:

ros2 topic echo /joint_states

3. Network Issues

If nodes can't discover each other:

Ensure both computers are on the same network
Check if ROS_DOMAIN_ID is set to the same value on both computers
Verify firewall settings
Try using the ROS_LOCALHOST_ONLY=0 environment variable

4. Debug Node Status

ros2 node list
ros2 node info /lerobot_teleop_leader  # or follower

Advanced Configuration

Quality of Service Settings

For teleoperation over unreliable networks, you can adjust QoS settings:

# Use reliable QoS instead of best effort (might increase latency but improve reliability)
--ros2_config.use_best_effort_qos=false

Publishing Rate

Adjust the rate at which joint states are published:

# On leader robot, set a lower rate for unreliable networks
--ros2_config.publish_rate_hz=100.0

Examples

Using with myCobot 280

For MyCobot robots, ensure you've set up the correct motor types:

Leader:

python lerobot/scripts/run_ros2_leader.py \
  --robot.type=mycobot \
  --robot.leader_arms.main.port=/dev/ttyUSB0 \
  --ros2_config.publish_rate_hz=100.0

Follower:

python lerobot/scripts/run_ros2_follower.py \
  --robot.type=mycobot \
  --robot.follower_arms.main.port=/dev/ttyUSB0

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