https://github.com/robidev/ros2_four_wheel_robot
This is a ROS2 package to interface a raspberry pi based four wheeled robot from LAFVIN with ROS2 topics for sensors, camera and motor/servo/led/buzzer controls
https://github.com/robidev/ros2_four_wheel_robot
lavfin raspberry-pi-4 ros2
Last synced: 17 days ago
JSON representation
This is a ROS2 package to interface a raspberry pi based four wheeled robot from LAFVIN with ROS2 topics for sensors, camera and motor/servo/led/buzzer controls
- Host: GitHub
- URL: https://github.com/robidev/ros2_four_wheel_robot
- Owner: robidev
- Created: 2025-07-13T09:52:00.000Z (11 months ago)
- Default Branch: main
- Last Pushed: 2025-07-13T11:01:24.000Z (11 months ago)
- Last Synced: 2025-07-13T12:29:02.236Z (11 months ago)
- Topics: lavfin, raspberry-pi-4, ros2
- Language: Python
- Homepage:
- Size: 465 KB
- Stars: 0
- Watchers: 0
- Forks: 0
- Open Issues: 0
-
Metadata Files:
- Readme: README.md
Awesome Lists containing this project
README
# ROS2 Four Wheel Robot
**ROS2 Four Wheel Robot** is the Raspberry Pi–side ROS 2(kilted) package responsible for directly interfacing with the robot's hardware components: motors, servos, LEDs, buzzer, OLED screen, line sensors, ADC (LDR, battery voltage), ultrasonic distance sensor, and camera.
This package exposes ROS 2 topics and services that allow remote control and sensor monitoring of the robot from a PC or onboard logic.
---
## 🔌 Hardware Controlled
| Component | Interface | ROS Topic(s) |
|------------------|--------------------------|--------------------------------------------------|
| **Motors** | 4-wheel driver via PWM | `/cmd_vel` (`geometry_msgs/Twist`) |
| **Servos** | PWM | `/servo/0/angle`, `/servo/1/angle` |
| **LEDs** | SPI (WS2812/NeoPixel) | `/led/set_color` (`Int32MultiArray`) |
| **Buzzer** | GPIO | `/buzzer` (`std_msgs/Bool`) |
| **OLED Display** | I2C | `/oled_text` (`std_msgs/String`) |
| **Line Sensors** | GPIO (IR modules) | `/line_tracking` (`Int8MultiArray`) |
| **Ultrasonic** | GPIO (HC-SR04) | `/ultrasonic/distance` (`sensor_msgs/Range`) |
| **ADC Sensors** | SPI/I2C ADC (LDR, batt) | `/sensors/ldr_left`, `/sensors/ldr_right`, `/sensors/battery_voltage` (`Float32`) |
| **Camera** | PiCam or USB via OpenCV | `/image_raw` (`sensor_msgs/Image`) |
---
## 🧩 Nodes Overview
| Node | Function |
|-------------------------|----------------------------------------------|
| `robot_controller_node` | Handles motor movement from `/cmd_vel` |
| `servo_controller_node` | Sets servo positions from angle topics |
| `led_controller_node` | Controls LEDs via RGB values |
| `line_tracking_node` | Publishes 3 IR sensors |
| `adc_sensor_node` | Reads LDR + battery voltage via ADC |
| `ultrasonic_node` | Publishes distance in meters |
| `buzzer_node` | Activates buzzer on `Bool(True)` |
| `oled_display_node` | Displays 2-line string messages |
| `camera_node` | Publishes video stream |
---
## 📦 Installation
First ensure ROS2 (kilted) is installed on the raspberry pi. I had to build it from source, which was non-trivial. I used a public LLM to assist me. By using the command `colcon build --symlink-install --packages-up-to demo_nodes_cpp --cmake-args -DBUILD_TESTING=OFF` you may avoid building the large packages such as gazebo and RViz. Then create a workspace like `~/ros2_ws/` where you can house the project.
```bash
cd ~/ros2_ws/src
git clone https://github.com/robidev/ros2_four_wheel_robot.git
cd ~/ros2_ws
colcon build --packages-select four_wheel_bot
source install/setup.bash
```
---
## 🚀 Launching
You can launch nodes individually or create a custom launch file:
```bash
ros2 run four_wheel_bot robot_controller_node
ros2 run four_wheel_bot led_controller_node
ros2 run four_wheel_bot line_tracking_node
...
```
Or launch all services with
```bash
ros2 launch four_wheel_bot all_nodes_launch
```
---
## 🧪 Testing with ROS 2 Topics
```bash
# Drive forward
ros2 topic pub /cmd_vel geometry_msgs/msg/Twist "{linear: {x: 0.2}, angular: {z: 0.0}}"
# Set servo angle
ros2 topic pub /servo/0/angle std_msgs/msg/Float32 "data: 90"
# Turn on red LED at index 0
ros2 topic pub /led/set_color std_msgs/msg/Int32MultiArray "{data: [0, 255, 0, 0]}"
# Display message on OLED
ros2 topic pub /oled_text std_msgs/msg/String "data: 'Hello\nWorld!'"
# Enable buzzer
ros2 topic pub /buzzer std_msgs/msg/Bool "data: true"
```
---
## 📜 License
MIT License. Created for embedded robotics experimentation.