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Middleware Configuration#

ROS 2 supports multiple middleware implementations (RMW). While DDS is default, Zenoh offers significant advantages for LSA applications.

Middleware Options#

DDS (Default)#

  • Fast-RTPS (ROS 2 Humble default)
  • Cyclone DDS (lightweight)
  • RTI Connext (commercial)

Tier 1 middleware optimized for autonomous vehicles with: - Better wireless/cellular performance - Lower latency and resource usage - Zero configuration - Cloud-native support

Zenoh for Low Speed Autonomy#

Performance Benefits#

  • Lower Latency: Up to 50% reduction in message latency compared to DDS
  • Higher Throughput: Better performance with large data streams (pointclouds, images)
  • Efficient Resource Usage: Lower CPU and memory footprint
  • Wireless Optimization: Superior performance on WiFi and cellular networks

Operational Advantages#

  • Zero Configuration: Works out-of-the-box without complex QoS tuning
  • Cloud Native: Seamless operation across local networks and internet
  • Cellular Support: Native unicast support for 4G/5G networks
  • Simplified Debugging: Built-in tools for monitoring and troubleshooting

LSA-Specific Benefits#

  • Multi-Vehicle Coordination: Efficient fleet communication
  • Remote Monitoring: Native support for cloud connectivity
  • Edge Computing: Optimized for distributed architectures
  • Dynamic Discovery: Better handling of intermittent connections

Installation#

Prerequisites#

Complete the Getting Started guide first.

Install Zenoh RMW#

# Add the Zenoh repository
echo "deb [trusted=yes] https://download.eclipse.org/zenoh/debian-repo/ /" | \
  sudo tee /etc/apt/sources.list.d/zenoh.list > /dev/null
sudo apt update

# Install RMW Zenoh
sudo apt install -y ros-humble-rmw-zenoh-cpp

Configuration#

Basic Setup#

  1. Set the RMW Implementation 

    # Add to ~/.bashrc for permanent configuration
echo 'export RMW_IMPLEMENTATION=rmw_zenoh_cpp' >> ~/.bashrc
source ~/.bashrc

# Or set temporarily for current session
export RMW_IMPLEMENTATION=rmw_zenoh_cpp

  2. Configure Zenoh Router (Optional but Recommended)

Create a Zenoh configuration file: 

cat > ~/zenoh_config.json5 << EOF
{
  mode: "router",
  listen: {
    endpoints: [
      "tcp/0.0.0.0:7447",
      "udp/0.0.0.0:7447"
    ]
  },
  scouting: {
    multicast: {
      enabled: true,
      address: "224.0.0.224:7446",
      interface: "auto"
    }
  }
}
EOF

  1. Start Zenoh Router 
    # Install Zenoh router
sudo apt install -y zenoh

# Run with configuration
zenohd -c ~/zenoh_config.json5

Advanced Configuration#

Network-Specific Settings#

For different network environments:

# WiFi Networks
export ZENOH_MULTICAST_SCOUTING=true
export ZENOH_UNICAST_SCOUTING=false

# Cellular Networks (4G/5G)
export ZENOH_MULTICAST_SCOUTING=false
export ZENOH_UNICAST_SCOUTING=true
export ZENOH_PEERS="tcp/router-ip:7447"

# Mixed Networks
export ZENOH_MULTICAST_SCOUTING=true
export ZENOH_UNICAST_SCOUTING=true

Performance Tuning#

# Optimize for low latency
export ZENOH_CACHE_SIZE=0
export ZENOH_BATCHING_ENABLED=false

# Optimize for high throughput
export ZENOH_CACHE_SIZE=10000
export ZENOH_BATCHING_ENABLED=true
export ZENOH_BATCH_SIZE=65536

Integration with Autoware#

Launch File Configuration#

Modify your Autoware launch files to use Zenoh:

<!-- autoware_zenoh.launch.xml -->
<launch>
  <!-- Set RMW implementation -->
  <set_env name="RMW_IMPLEMENTATION" value="rmw_zenoh_cpp"/>

  <!-- Include standard Autoware launch -->
  <include file="$(find-pkg-share autoware_launch)/launch/autoware.launch.xml">
    <arg name="vehicle_model" value="$(var vehicle_model)"/>
    <arg name="sensor_model" value="$(var sensor_model)"/>
  </include>
</launch>

Multi-Vehicle Setup#

For fleet deployments:

# Vehicle 1
export ROS_DOMAIN_ID=1
export ZENOH_SESSION_NAME="vehicle_1"

# Vehicle 2
export ROS_DOMAIN_ID=2
export ZENOH_SESSION_NAME="vehicle_2"

# Central Router (Fleet Coordinator)
zenohd --id fleet_router --listen tcp/0.0.0.0:7447

Switching Between Middleware#

You can easily switch between different RMW implementations:

# Use Zenoh
export RMW_IMPLEMENTATION=rmw_zenoh_cpp

# Switch back to Fast DDS
export RMW_IMPLEMENTATION=rmw_fastrtps_cpp

# Use Cyclone DDS
export RMW_IMPLEMENTATION=rmw_cyclonedds_cpp

Monitoring and Debugging#

Zenoh Tools#

# Install Zenoh tools
sudo apt install -y zenoh-tools

# Monitor active sessions
z_info

# Scout for Zenoh nodes
z_scout

# Monitor data flow
z_sub -k "/**"

ROS 2 Introspection#

# List active nodes
ros2 node list

# Check middleware in use
ros2 doctor --report | grep middleware

# Monitor topic bandwidth
ros2 topic bw /sensing/lidar/concatenated/pointcloud

Troubleshooting#

Common Issues#

  1. Nodes not discovering each other 

    # Check multicast is enabled
ip link show | grep MULTICAST

# Verify Zenoh router is running
ps aux | grep zenohd

  2. High latency on WiFi 

    # Disable power saving
sudo iw dev wlan0 set power_save off

# Set WiFi to performance mode
sudo iwconfig wlan0 rate 54M fixed

  3. Connection issues over cellular 

    # Use explicit peer configuration
export ZENOH_PEERS="tcp/central-server-ip:7447"

Fallback to DDS#

If issues persist, you can always fall back to DDS: 

unset RMW_IMPLEMENTATION
# Or explicitly set
export RMW_IMPLEMENTATION=rmw_cyclonedds_cpp

Best Practices#

  1. Development: Use Cyclone DDS for simplicity
  2. Testing: Validate with target middleware early
  3. Production: Deploy with Zenoh for optimal performance
  4. Fleet: Use centralized Zenoh routers
  5. Remote: Configure explicit peers for cellular

Next Steps#