servo_publisher

Overview

The servo_publisher ROS 2 package controls a servo motor using a Raspberry Pi and publishes the servo's angle to a ROS 2 topic. The servo's rotation is controlled via PWM signals, and the package continuously rotates the servo smoothly between specified angles while publishing the angle values to a ROS 2 topic.

Requirements

• ROS 2 (any compatible version, e.g., Foxy, Galactic, or Humble)
• Python 3
• gpiozero library
• pigpio library
• Raspberry Pi with a compatible servo and GPIO pin setup

Installation

1. Set up your ROS 2 workspace (if not already done):

   mkdir -p ~/ros2_ws/src
   cd ~/ros2_ws

2. Clone the repository:

   cd ~/ros2_ws/src
   git clone https://github.com/FarrukhAijaz/servo_publisher.git

3. Install dependencies:

   Make sure you have gpiozero and pigpio installed on your Raspberry Pi:

   sudo apt-get update
   sudo apt-get install python3-gpiozero pigpio

4. Build the workspace:

   cd ~/ros2_ws
   colcon build

5. Source the workspace:

   source install/setup.bash

Usage

1. Start the pigpio daemon (this is necessary for gpiozero to work with the PiGPIOFactory):

   sudo pigpiod

2. Run the ROS 2 node:

   ros2 run servo_publisher servo_publisher

Configuration

The servo_publisher package is configured with the following parameters:

• MIN_PULSE_WIDTH: Minimum pulse width for the servo (500 µs).
• MAX_PULSE_WIDTH: Maximum pulse width for the servo (2500 µs).
• SERVO_PIN: GPIO pin connected to the servo (default is 12).
• ROTATION_SPEED: Delay in seconds between angle updates (default is 0.1).
• ANGLE: Reference value to adjust the servo at a planar surface (default should be 0 degrees).
• OFFSET: Offset angle for the servo to move between ± X degrees (default is 20 degrees).

Adjust these parameters in the rotation.py file as needed.

Circuit Configuration

• IMPORTANT: Ensure Common Grounding of the Pi and the servo.

Troubleshooting

• No movement: Ensure that the pigpio daemon is running (sudo pigpiod).
• No ROS 2 messages: Verify that your ROS 2 environment is properly sourced and that the servo_publisher node is running.

License

This package is licensed under the GNU General Public License (GPL). See the LICENSE file for details.

Contact

For any issues or questions, please contact Farrukh Aijaz at [email protected].