Astromech

Overview

Astromech is a Python-based project for controlling a robotic droid, designed to run on a Raspberry Pi with servo motors and sensors. The project includes functionality for movement control, heading maintenance using a PID controller, and obstacle detection via ultrasonic sensors. It leverages an MPU6050 for orientation tracking and the Adafruit ServoKit for servo motor control.

This repository, maintained by mmandenach13, is located at github.com/mmandenach13/astromech.

Features

• Movement Control: Drive and rotate the droid using DC motors for wheels and standard servos for shoulder mechanisms.
• PID Heading Control: Maintains a specified heading using a PID controller with data from an MPU6050 sensor.
• Obstacle Detection: Uses ultrasonic distance sensors to detect obstacles and adjust the droid's behavior.
• Modular Design: Organized into classes (Droid, MovementServos, MPU, SensorArray) for easy maintenance and extensibility.

Hardware Requirements

• Raspberry Pi (e.g., Raspberry Pi 4)
• MPU6050 gyroscope/accelerometer
• Ultrasonic distance sensors (e.g., HC-SR04, with trigger and echo pins)
• Adafruit PCA9685 Servo Controller
• DC motors for wheels (I used a hacked Roomba)
• Standard servos for shoulder mechanisms
• Appropriate power supply and wiring for components

Software Requirements

See requirements.txt for Python dependencies. Key libraries include:

• adafruit-circuitpython-servokit
• smbus
• gpiozero

Installation

1. Clone the Repository:

   git clone https://github.com/mmandenach13/astromech.git
   cd astromech

2. Set Up a Virtual Environment (optional but recommended):

   python3 -m venv venv
   source venv/bin/activate

3. Install Dependencies:

   pip install -r requirements.txt

4. Configure Hardware:

   • Connect the MPU6050 to the Raspberry Pi I2C pins.
   • Connect ultrasonic sensors to the specified GPIO pins (left: 22/18, center: 17/27, right: 23/24).
   • Connect servos to the Adafruit PCA9685 channels (shoulders: 0, 1).
   • Connect motor driver pins to 7, 8, 9, and 10 for wheel control.

Usage

1. Run the Main Droid Program:

   python3 droid.py

   The droid will move forward while maintaining a heading (0° or 180°, alternating), stop when an obstacle is closer than 40 cm, turn 180°, and continue. Press Ctrl+C to stop.

2. Test Individual Components:

   • Servo Test:

     python3 servo_test.py

     Test servo channel 0 (angle) and channel 1 (continuous).
   • MPU Test:

     python3 mpu_test.py

     Displays the current heading from the MPU6050.

3. Key Files:

   • droid.py: Main program controlling the droid's behavior.
   • movement.py: Handles servo motor control for wheels and shoulders.
   • controls.py: Manages MPU6050 and ultrasonic sensor interactions.
   • servo_test.py: Tests servo functionality.
   • mpu_test.py: Tests MPU6050 heading tracking.

Notes

• Ensure proper GPIO cleanup by handling KeyboardInterrupt (Ctrl+C) to reset servos and GPIO pins.
• The left ultrasonic sensor is currently non-functional (returns -1 in SensorArray.read_all()).
• Adjust PID constants (kp, ki, kd) or motor bias in droid.py for better heading control if needed.
• The shoulder servo range is limited to ±30° to prevent damage.

Contributing

Contributions are welcome! Please submit issues or pull requests to github.com/mmandenach13/astromech.

License

This project is licensed under the MIT License. See the LICENSE file for details.