GPS Autonomous Robot

A 5-week independent study project exploring GPS/IMU sensor fusion for precise localization on a small autonomous ground vehicle, with trajectory control as a follow-up application.

Project Goals

Primary: Improve GPS positional accuracy by fusing GPS data with IMU measurements.

Secondary: Implement trajectory tracking/control using the fused localization output.

Long-term (optional): Add camera and LiDAR for full autonomous navigation.

Platform

Compute: Radxa Rock5C (RK3588S)

Robot: 4-wheeled RC car frame

• Ackermann front-wheel steering (servo)
• All-wheel drive via central BLDC motor
• Differential per axle

Sensors

Sensor	Interface	Role	Wiring
u-blox 7 USB GPS dongle	USB	Absolute position (GNSS)	USB port
MPU-6050	I2C8	Linear acceleration + angular velocity	SDA (Pin3) + SCL (Pin5)

Actuators

Component	Interface	Role	Wiring
VESC	UART2	Motor control	Pin8 (TX) + Pin10 (RX)
Steering Servo	PWM	Steering	Connected to VESC PWM output pins

Motor Controller (VESC)

The BLDC motor and steering servo are controlled by a VESC motor controller, configured via VESC Tool — an open-source GUI application that connects over USB or UART. Key settings include motor type (BLDC), current limits, and servo output range.

Software Stack

• OS: Linux (Rock5C)
• Middleware: ROS2
• Sensor fusion: -TBD-
• GPS driver: -TBD-
• IMU driver: -TBD-

Architecture (planned)

-TBD-

Project Structure

gps_autonomous_robot/
├── 01_Documents/          # Reports and references
└── README.md

Status

• Hardware platform selected
• Hardware assembly
• ROS2 environment setup on Rock5C
• GPS driver integration & testing
• IMU driver integration & testing
• EKF sensor fusion tuning
• Trajectory controller implementation
• Field testing

Hardware Setup

Software Setup

Activating hardware overlays

I2C8 and UART2 have to be activated with rsetup

Add user to group to access serial port

sudo usermod -aG dialout radxa

Allow reading controller data

The PS4 controller is accessed via /dev/hidraw0. By default only root can open it, so a udev rule is needed:

sudo tee /etc/udev/rules.d/99-hidraw-plugdev.rules <<'EOF'
KERNEL=="hidraw*", SUBSYSTEM=="hidraw", GROUP="plugdev", MODE="0660"
EOF
sudo udevadm control --reload-rules && sudo udevadm trigger

Replug the controller afterwards. The radxa user is already in plugdev, so no further group changes are needed.

Fix missing PyCRC dependency for pyvesc

The pyvesc package requires a PyCRC library that is no longer available on PyPI (the name was taken over by an unrelated package). A compatibility shim must be created manually:

mkdir -p ~/.local/lib/python3.11/site-packages/PyCRC

Create ~/.local/lib/python3.11/site-packages/PyCRC/__init__.py (empty) and CRCCCITT.py implementing CRC-CCITT (XModem, poly=0x1021, init=0x0000).

ROS2 Humble Installation (pre-built archive for Rock5C)

The following steps apply when using the pre-built ros2_humble.tar.gz archive (built for the radxa user on Rock5C). A standard sudo apt install ros-humble-* will not work on this board.

1. Extract to the correct location

The archive contains hardcoded paths for /home/radxa/ros2_humble. Extract it there:

sudo tar -xzf /path/to/ros2_humble.tar.gz -C /home/radxa/

Do not extract to /home/ directly — the Python egg-link files will point to the wrong paths and ROS2 will fail to start.

2. Install missing system libraries

sudo apt install -y libspdlog-dev python3-packaging python3-dev python3-netifaces

3. Install missing Python module

pip install lark --break-system-packages

This is required for ros2 launch to work.

4. Source the setup file

source ~/ros2_humble/install/setup.bash

Add to ~/.bashrc to make it permanent.

5. Verify

ros2 launch --help

Notes

• MPU-6050 provides 6-DOF (accel + gyro), no magnetometer