System Overview

I built a distributed ROS 2 system for gesture-based robotic control with three main nodes:

• Raspberry Pi 5: Camera capture and basic processing (Ubuntu 24.04, ROS 2 Jazzy)

• Development Machine: Computer vision algorithms and parameter tuning

• MacBook Pro (VM): GUI applications and visualization via Ubuntu 24.04 ARM VM (UTM)

• Network: WiFi 6

The expected data rate was 30 Hz end-to-end. Actual performance was 1 Hz with frequent topic dropouts and unresponsive GUI tools.

Problem 1: Network Saturation from Raw Image Streams

The Pi 5 camera node published /camera/image_raw and /camera/image_raw/compressed. Local testing confirmed 30 Hz performance. On the dev machine, the raw topic dropped frequently while the compressed topic remained stable.

Root Cause

Bandwidth calculations exposed the bottleneck:

• Raw (640×480 RGB @ 30 Hz): ≈27 MB/s

• Compressed (JPEG): ≈3 MB/s

ROS 2 discovery and transport failed to maintain raw topic streaming over WiFi. The system choked on the 27 MB/s stream.

Fix: Compressed-Only Streaming and Local Decompression

Step 1: Disable raw topic in launch file

<remap from="/camera/image_raw" to="/dev/null"/>

Step 2: Decompression node on dev machine

# Subscribes to /camera/image_raw/compressed
# Publishes /camera/image_raw

Results