Rovers ROS

ROS 2 workspace for the RIT SPEX rover (Scorpio). Runs on the Nvidia Jetson Orin Nano.

Shared Protocol Submodule

This repository depends on the shared protocol package (rovers-protocol) for encoding/decoding messages from the basestation. The same protocol repo is used by both this repo and rovers-basestation.

# Clone with submodule
git clone --recurse-submodules https://github.com/rit-spex/rovers-ros.git

# Or if already cloned
git submodule update --init --recursive

Expected submodule location: lib/rovers-protocol/

How it works

The basestation sends controller data over XBee radio as compact bit-packed bytes. The basestation_node decodes them using MessageEncoder from the shared protocol and publishes the values as ROS topics. The telemetry_uplink_node collects rover telemetry from ROS topics, encodes them using the same protocol, and sends them back to the basestation over UDP.

                        XBee Radio
  ┌───────────────┐   ───────────────> ┌─────────────────┐
  │ BASESTATION   │   controller data  │  ROVER (ROS 2)  │
  │ (Raspberry Pi)│  <───────────────  │  (this repo)    │
  │               │   telemetry (UDP)  │                 │
  └───────────────┘                    └─────────────────┘

ROS nodes that use the protocol

Node	File	Purpose
basestation_node	src/communications/basestation/basestation/basestation_node.py	Decodes XBee messages → ROS topics
telemetry_uplink_node	src/communications/basestation/basestation/telemetry_uplink_node.py	Encodes rover telemetry and sends it to the basestation via UDP

Protocol Trace Debugging

You can enable real-time hex-level protocol tracing to verify that the rover is correctly encoding/decoding messages. This is useful for confirming bit-packed message IDs and field values match what the basestation expects.

To enable tracing, pass the protocol_trace:=1 argument:

# In simulation
ros2 launch main simulation_launch.xml protocol_trace:=1

# On hardware (SSH in and run)
ros2 launch main main_launch.xml protocol_trace:=1

When enabled, the basestation_node and telemetry_uplink_node will print hex traces like:

• [protocol rx] <ID:0x02> data:0200ff... (Xbox control message)
• [protocol tx] <ID:0xF1> data:f1045a... (Telemetry message)

---

Building

Make sure you have ROS 2 (Humble) installed, then:

colcon build
source source.sh

Running

# Launch the full system
ros2 launch main main_launch.xml

# Launch the simulator
ros2 launch main simulation_launch.xml

Connection

SSH to the rover:

ssh rovers@129.21.91.140
# Password: rovers

Then:

cd ~/ros/rovers-ros
source source.sh
ros2 launch main main_launch.xml

After you see "starting xbee..." enter the password rovers.