Husky A200 × Unitree Go2: Multi-Robot Communication over ROS 2 + zenoh

Code and lab notes for making a Clearpath Husky A200 and a Unitree Go2 EDU quadruped work together over campus Wi‑Fi. The Husky reads the dog's odometry and sends it motion and posture commands, even though the two robots run different ROS 2 distributions (Jazzy ↔ Foxy) and the campus network blocks multicast, which normally breaks ROS 2 discovery.

Husky bring-up, mapping and datasets live in HuskyA200. This repository holds everything that involves both robots.

Status

Capability	Status
Go2 state → ROS 2 (/go2/odom, 50 Hz) via unitree_sdk2	✅ Working on the Go2's Jetson
Go2 → Husky odometry over Wi‑Fi	✅ ros2 topic echo /go2/odom on the Husky
Husky → Go2 stand_up / stand_down (/go2/command)	✅ Verified on the real dog (2026-10-13)
Husky → Go2 velocity (/go2/cmd_vel)	🟡 Reaches go2_bridge; walking test while standing is next
One-command startup (launch scripts)	⬜ Currently 4 terminals

Architecture

flowchart LR
  subgraph G["Unitree Go2 EDU · Jetson · ROS 2 Foxy"]
    MCU["Motion MCU<br/>Unitree DDS, domain 0"] <--> BR["go2_bridge<br/>(unitree_sdk2)"]
    BR <-->|"ROS_DOMAIN_ID=1"| ZG["zenoh-bridge-ros2dds<br/>(connect)"]
  end
  subgraph H["Clearpath Husky A200 · Ubuntu 24.04 · ROS 2 Jazzy"]
    ZH["zenoh-bridge-ros2dds<br/>(listen, TCP 7447)"] <--> APP["Husky ROS 2 nodes / CLI"]
  end
  ZG <-->|"/go2/* only<br/>TCP over campus Wi-Fi"| ZH

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Key design decisions:

• zenoh instead of plain DDS discovery. zenoh-bridge-ros2dds carries ROS 2 traffic over a single unicast TCP link. That works without multicast and across Foxy ↔ Jazzy. An allow-list keeps it to /go2/*.
• Separate ROS domain on the Go2. The dog's own services use DDS domain 0. Running our nodes there flooded go2_bridge with bad_alloc, so all of our ROS nodes on the Go2 use ROS_DOMAIN_ID=1.
• Topics, not services, across robots. ROS services don't cross the zenoh bridge with Fast DDS, so remote posture commands use the /go2/command topic.
• SDK-first CycloneDDS. unitree_sdk2 bundles a newer CycloneDDS than ROS Foxy. CMakeLists.txt puts the SDK's headers first and sets an RPATH so the right libddsc loads at runtime.

Repository layout

Husky-Go2-MultiRobot/
├── go2_bridge/                  ROS 2 package that runs on the Go2's Jetson (C++, unitree_sdk2)
│   ├── src/go2_bridge.cpp
│   └── config/go2_zenoh.json5   zenoh allow-list shared by both robots
├── go2_tools/go2_state_test/    SDK-only state reader, no ROS (skipped by colcon)
└── docs/                        Dated lab notes: setup, problems, root causes, results

Quick start

On the Go2 (ROS 2 Foxy, unitree_sdk2 installed to /opt/unitree_robotics):

mkdir -p ~/go2_ws/src && cd ~/go2_ws/src
git clone https://github.com/greenaandblue/Husky-Go2-MultiRobot.git
cd ~/go2_ws && source /opt/ros/foxy/setup.bash
colcon build --packages-select go2_bridge --parallel-workers 1

Daily startup. Start the four terminals in the order A → C → B → D:

# A — Go2: go2_bridge
source /opt/ros/foxy/setup.bash && source ~/go2_ws/install/setup.bash
export RMW_IMPLEMENTATION=rmw_fastrtps_cpp ROS_DOMAIN_ID=1
ros2 run go2_bridge go2_bridge --ros-args -r __ns:=/go2 -p network_interface:=eth0 -p max_vx:=0.2

# C — Husky: zenoh bridge (listen)
source /opt/ros/jazzy/setup.bash && source /etc/clearpath/setup.bash
zenoh-bridge-ros2dds -c ~/go2_zenoh.json5 -l tcp/0.0.0.0:7447

# B — Go2: zenoh bridge (connect to the Husky)
source /opt/ros/foxy/setup.bash
export RMW_IMPLEMENTATION=rmw_fastrtps_cpp ROS_DOMAIN_ID=1
zenoh-bridge-ros2dds -c ~/go2_ws/src/Husky-Go2-MultiRobot/go2_bridge/config/go2_zenoh.json5 \
  -e tcp/<husky-ip>:7447

# D — Husky: test
ros2 topic echo /go2/odom --once
ros2 topic pub --once -w 1 /go2/command std_msgs/msg/String "{data: stand_up}"
ros2 topic pub --once -w 1 /go2/command std_msgs/msg/String "{data: stand_down}"

If the Husky prints Waiting for at least 1 matching subscription(s) forever, terminal B or A isn't running.

go2_bridge interface

Name	Type	Direction	Description
/go2/odom	nav_msgs/Odometry	out, 50 Hz	Pose from rt/sportmodestate, twist rotated into the body frame (go2/odom → go2/base_link)
/go2/cmd_vel	geometry_msgs/Twist	in	SportClient::Move(vx, vy, wz), clamped by max_vx / max_vy / max_wz; stops after cmd_timeout without input
/go2/command	std_msgs/String	in	stand_up (StandUp → BalanceStand), stand_down, recovery_stand, stop
/go2/stand_up, /stand_down, /stop	std_srvs/Trigger	service	Local use on the Go2 only

Parameters: network_interface (required, e.g. eth0), max_vx 0.5 m/s, max_vy 0.3 m/s, max_wz 0.8 rad/s, cmd_timeout 0.5 s, odom_frame, base_frame, odom_rate 50 Hz.

Documentation

Document	Contents
docs/2026-10-12_husky_go2_comm_summary.md	One-page progress summary (EN + 中文), updated 2026-10-13
docs/2026-10-12_husky_go2_comm_detailed.md	Full setup log: system configuration, one-time setup on both robots, chronological problems / root causes / fixes, troubleshooting table

Adding new work

This repository is the home for all future Husky ↔ Go2 work. Conventions:

What	Where
New ROS 2 packages	Top level, one folder per package (e.g. go2_bridge/)
Launch / startup scripts	scripts/
Shared configs used by both robots	Inside the package that owns them, or config/
Lab notes and test results	docs/YYYY-MM-DD_<topic>.md; images in docs/images/
Tools not built by colcon	go2_tools/ (has COLCON_IGNORE)

Roadmap

• Walking test: /go2/cmd_vel from the Husky while the dog is standing
• Measure Wi‑Fi gaps on /go2/cmd_vel; tune cmd_timeout (≈1.0 s)
• Launch scripts for both robots to replace the 4-terminal startup
• Persistent Go2 network fixes (ipv4.never-default, power_save off) and NTP time sync
• Verify the /go2/odom twist frame; relate go2/odom to the Husky's TF tree for joint tasks
• Restrict the zenoh port (currently open without authentication)

Maintainer

Huihang Liu · Computer Engineering, Penn State · @greenaandblue