Autonomous Navigation

ROS2 autonomous navigation package for GPS waypoint following and obstacle avoidance.

Nodes

1. Simple Waypoint Follower (simple_waypoint_follower)

Autonomous GPS waypoint navigation with obstacle avoidance.

• Subscribes to:
  • /fix (NavSatFix) - GPS position
  • /imu/data (Imu) - Heading/orientation
  • /scan (LaserScan) - LiDAR obstacle detection
  • /gps_waypoints (Float64MultiArray) - Waypoint list [lat1, lon1, lat2, lon2, ...]
• Publishes to:
  • /cmd_vel (Twist) - Velocity commands
• Features:
  • Follows GPS waypoints in sequence
  • Obstacle avoidance using LiDAR
  • Adjusts speed based on heading error
  • Stops at final waypoint

2. Simple Autonomous Navigation (simple_autonomous_navigation)

Basic autonomous navigation without GPS waypoints.

• Subscribes to:
  • /scan (LaserScan) - LiDAR obstacle detection
• Publishes to:
  • /cmd_vel (Twist) - Velocity commands
• Features:
  • Moves forward in straight line when path is clear
  • Turns to avoid obstacles
  • No GPS or IMU required

3. Rover Serial Bridge (rover_serial_bridge)

Converts ROS2 Twist commands to rover motor commands and publishes IMU data.

• Subscribes to:
  • /cmd_vel (Twist) - Velocity commands from autonomous navigation
  • /JSON (String) - Direct motor commands from UI for manual control
• Publishes to:
  • /imu/data (Imu) - IMU sensor data
  • /imu/raw (Float32MultiArray) - Raw IMU values [roll, pitch, yaw, temp, voltage]
• Features:
  • Differential drive conversion (Twist → left/right wheel speeds)
  • Serial communication with rover hardware ({"T": 1, "L": left, "R": right})
  • IMU data streaming at 50 Hz
  • Safety watchdog (sends stop commands if no recent messages)

4. Rover Command Centre (rover_command_centre)

Central hub for managing all rover subsystems.

• Subscribes to:
  • /command (String) - Commands from external software (LaunchRover, ManualControl, Stop)
  • /heartbeat (String) - Keepalive from external software
• Publishes to:
  • /timestamp (String) - System timestamp when operational
  • /node_status (String) - Status of all nodes (JSON)
• Features:
  • Launches/stops GPS, LiDAR, cameras, and navigation nodes
  • Monitors node health
  • Emergency stop on heartbeat loss
  • Process management and cleanup

Launch

Using Rover Command Centre (Recommended)

The command centre manages all subsystems including GPS and LiDAR:

# Start the command centre
ros2 run command_centre rover_command_centre

# Send commands via ROS topics or external UI
# - LaunchRover: Starts GPS, LiDAR, cameras, and autonomous navigation
# - ManualControl: Starts sensors for manual control via UI
# - Stop: Stops all nodes safely

The command centre automatically launches:

• GPS: ros2 run nmea_navsat_driver nmea_serial_driver
• LiDAR: ros2 launch obstacle_detection obstacle_detector.launch.py (includes rplidar)
• Cameras: CSI and USB camera nodes
• Navigation: simple_waypoint_follower or rover control

Manual Launch (For Testing)

Launch Waypoint Follower Navigation

# Terminal 1: Start GPS
ros2 run nmea_navsat_driver nmea_serial_driver

# Terminal 2: Start LiDAR
ros2 launch rplidar_ros rplidar_a1_launch.py

# Terminal 3: Start navigation stack
ros2 launch autonomous_navigation autonomous_navigation.launch.py

This launches:

• simple_waypoint_follower - GPS waypoint navigation
• rover_serial_bridge - Motor control and IMU

Launch Simple Autonomous Navigation (No GPS)

# Terminal 1: Start LiDAR
ros2 launch rplidar_ros rplidar_a1_launch.py

# Terminal 2: Start navigation
ros2 run autonomous_navigation simple_autonomous_navigation
ros2 run autonomous_navigation rover_serial_bridge

Configuration

Edit parameters in config/waypoint_follower.yaml:

simple_waypoint_follower:
  ros__parameters:
    max_linear_speed: 0.1      # m/s - Forward speed
    max_angular_speed: 0.2     # rad/s - Turning speed
    waypoint_threshold: 2.0    # meters - Distance to consider waypoint reached
    obstacle_distance: 0.5     # meters - Stop distance from obstacles
    obstacle_angle: 60.0       # degrees - Front detection sector width

rover_serial_bridge:
  ros__parameters:
    port: '/dev/ttyAMA0'       # Serial port (GPIO pins)
    # port: '/dev/rover_serial' # Or USB port

Sending Waypoints

Waypoints are sent to /gps_waypoints as a flat array of alternating latitude/longitude pairs:

from std_msgs.msg import Float64MultiArray

msg = Float64MultiArray()
msg.data = [lat1, lon1, lat2, lon2, lat3, lon3, ...]  # Alternating lat/lon pairs
publisher.publish(msg)

Example via command line:

ros2 topic pub --once /gps_waypoints std_msgs/msg/Float64MultiArray \
  "{data: [45.3158, -75.8378, 45.3159, -75.8379, 45.3160, -75.8380]}"

Manual Control via UI

The rover can be manually controlled through the UI by publishing JSON commands to /JSON:

{"T": 1, "L": 50, "R": 50}  // Move forward
{"T": 1, "L": -50, "R": -50}  // Move backward
{"T": 1, "L": 50, "R": -50}  // Turn right
{"T": 1, "L": 0, "R": 0}  // Stop

Important Notes

⚠️ GPS and LiDAR: When using the Rover Command Centre, GPS and LiDAR nodes are launched automatically. Manual launch is only needed for testing individual components.

⚠️ Serial Port Permissions: Ensure proper permissions for serial devices:

sudo usermod -a -G dialout $USER
# Then log out and back in

⚠️ Speed Configuration: Adjust speed multipliers in rover_serial_bridge.py if the rover moves too fast/slow:

• Line ~108: int(left * 1) - Change multiplier (currently 1)
• Speed ranges depend on your rover's motor controller

Dependencies

• rclpy
• sensor_msgs
• geometry_msgs
• std_msgs
• pyserial
• numpy
• tf_transformations
• psutil (for command centre)

Installation

Prerequisites

• ROS2 Jazzy
• Ubuntu 24.04 (recommended)

Setup Instructions

1. Clone the repository into your ROS2 workspace:

   cd ~/ros2_ws/src
   git clone https://github.com/ByteSizedRobotics/autonomous-navigation.git

2. Navigate to your workspace directory:

   cd ~/ros2_ws

3. Build the packages:

   colcon build --symlink-install

4. Source the workspace:

   source install/setup.bash

Run the MAIN launch file

ros2 launch obstacle_detection main.launch.py

This should launch the current implemented modules (GPS, Manual Control with Front-end, LiDAR, Live-CSI Camera Stream)