Robi

• DC motor control with PWM speed regulation
• Servo motor positioning for directional movement
• Sensor integration for obstacle detection
• Audio feedback system with alert sounds
• Modular architecture separating hardware concerns
• Low-level GPIO programming with bcm2835 library
• Real-time obstacle avoidance

Overview

Robi is an embedded robotics system built on Raspberry Pi hardware using C programming. The project demonstrates low-level hardware control, implementing autonomous navigation capabilities through sensor integration, PWM motor control, and real-time decision-making algorithms.

Tech Stack

Hardware

• Raspberry Pi 3/4 (primary controller)
• DC motors with PWM control
• Servo motors for positioning
• Ultrasonic/IR distance sensors
• Audio output hardware

Software

• C programming language
• bcm2835 library (GPIO access)
• GCC compiler
• Makefile build system

Architecture

Robi follows a modular architecture with clear separation of hardware control concerns:

// Example: Motor control with PWM
void motor_control_init() {
    bcm2835_gpio_fsel(MOTOR_PIN_1, BCM2835_GPIO_FSEL_OUTP);
    bcm2835_gpio_fsel(MOTOR_PIN_2, BCM2835_GPIO_FSEL_OUTP);
    bcm2835_pwm_set_mode(0, 1, 1);
    bcm2835_pwm_set_range(0, PWM_RANGE);
}
 
void set_motor_speed(int speed) {
    // PWM duty cycle control for speed regulation
    bcm2835_pwm_set_data(0, speed);
}

Project Structure

The codebase is organized into four functional modules:

1. Motor Control: DC motor speed regulation using PWM signals
2. Servo Management: Positioning control for directional movement
3. Sensor Interface: Obstacle detection and distance measurement
4. Common Utilities: Shared functionality and hardware abstractions

Key Features

PWM Motor Control

Precise speed regulation for DC motors using Pulse Width Modulation, enabling smooth acceleration, deceleration, and variable speed control for autonomous navigation.

Servo Positioning

Accurate angular control of servo motors for steering and sensor platform orientation, allowing the robot to navigate and scan its environment.

Obstacle Detection

Real-time sensor processing to identify obstacles and make autonomous navigation decisions. The system can detect objects in the robot's path and trigger appropriate responses.

Audio Feedback

Integrated sound system providing operational feedback through MP3 playback, including alert sounds when obstacles are detected for debugging and demonstration purposes.

Low-Level Hardware Control

Direct GPIO manipulation using the bcm2835 library, demonstrating understanding of embedded systems programming and hardware interfacing at the register level.

Technical Highlights

// Example: Obstacle detection and response
void autonomous_navigation() {
    while (running) {
        int distance = read_sensor();
 
        if (distance < OBSTACLE_THRESHOLD) {
            // Obstacle detected
            play_alert_sound();
            stop_motors();
            turn_servo(TURN_ANGLE);
            // Continue navigation
        } else {
            // Path is clear
            set_motor_speed(NORMAL_SPEED);
        }
    }
}

Building and Running

# Compile the project
make
 
# Run the robot (requires root for GPIO access)
sudo ./robi

Use Cases

This project demonstrates:

• Embedded systems development with C
• Real-time hardware control and sensor processing
• Autonomous navigation algorithm implementation
• GPIO programming and hardware interfacing
• Modular software architecture for robotics
• Integration of multiple hardware components

Perfect for understanding the fundamentals of robotics programming, embedded systems design, and low-level hardware control on single-board computers.