Building My First Autonomous Robot: A Complete Project Showcase

Project Overview

This post showcases my first major robotics project: an autonomous line-following robot built during my junior year. This project demonstrates key robotics concepts including sensor integration, control algorithms, and real-time decision making.

Project Goals:

• Build a robot that can autonomously follow a black line on a white surface
• Implement PID control for smooth navigation
• Add obstacle detection and avoidance capabilities
• Create a user-friendly interface for monitoring and control

Technical Specifications

Hardware Components

Software Stack

• Programming Language: C++ (Arduino IDE)
• Libraries Used:
  • Servo.h for servo control
  • NewPing.h for ultrasonic sensor
  • Custom PID controller implementation
• Computer Vision: Basic edge detection algorithms
• Communication: Serial communication for debugging

Design Process

1. Initial Concept and Research

I started by researching existing line-following robots and studying different approaches:

• Sensor-based approach: Using IR sensors to detect line contrast
• Vision-based approach: Using camera for line detection
• Hybrid approach: Combining both methods for reliability

After analysis, I chose the hybrid approach for better performance in varying lighting conditions.

2. Mechanical Design

The chassis design focused on:

• Stability: Low center of gravity with wide wheelbase
• Modularity: Easy component mounting and replacement
• Accessibility: Clear access to all components for debugging

// Example: Motor control function
void moveRobot(int leftSpeed, int rightSpeed) {
    // Constrain speeds to valid range
    leftSpeed = constrain(leftSpeed, -255, 255);
    rightSpeed = constrain(rightSpeed, -255, 255);

    // Control left motor
    if (leftSpeed >= 0) {
        digitalWrite(LEFT_MOTOR_DIR, HIGH);
        analogWrite(LEFT_MOTOR_PWM, leftSpeed);
    } else {
        digitalWrite(LEFT_MOTOR_DIR, LOW);
        analogWrite(LEFT_MOTOR_PWM, -leftSpeed);
    }

    // Control right motor
    if (rightSpeed >= 0) {
        digitalWrite(RIGHT_MOTOR_DIR, HIGH);
        analogWrite(RIGHT_MOTOR_PWM, rightSpeed);
    } else {
        digitalWrite(RIGHT_MOTOR_DIR, LOW);
        analogWrite(RIGHT_MOTOR_PWM, -rightSpeed);
    }
}

Implementation Highlights

PID Control Algorithm

The heart of the project is the PID (Proportional-Integral-Derivative) controller that keeps the robot centered on the line:

class PIDController {
private:
    float kp, ki, kd;
    float previousError;
    float integral;

public:
    PIDController(float p, float i, float d) : kp(p), ki(i), kd(d) {
        previousError = 0;
        integral = 0;
    }

    float calculate(float setpoint, float measured) {
        float error = setpoint - measured;
        integral += error;
        float derivative = error - previousError;

        float output = kp * error + ki * integral + kd * derivative;
        previousError = error;

        return output;
    }
};

Sensor Fusion

I implemented a sensor fusion algorithm that combines IR sensor data with camera input:

int calculateLinePosition() {
    // Read IR sensors
    int sensorValues[5];
    for (int i = 0; i < 5; i++) {
        sensorValues[i] = digitalRead(sensorPins[i]);
    }

    // Calculate weighted average
    int sum = 0, weightedSum = 0;
    for (int i = 0; i < 5; i++) {
        if (sensorValues[i] == 1) {  // Line detected
            sum++;
            weightedSum += i * 100;  // Weight by position
        }
    }

    if (sum > 0) {
        return weightedSum / sum - 200;  // Center at 0
    }

    return lastKnownPosition;  // Use last known position if no line detected
}

Challenges and Solutions

Challenge 1: Inconsistent Line Detection

Problem: The robot would lose the line in areas with varying lighting conditions.

Solution:

• Implemented adaptive thresholding
• Added calibration routine for different environments
• Combined multiple sensor types for redundancy

Challenge 2: Oscillation Around the Line

Problem: The robot would zigzag excessively instead of smooth following.

Solution:

• Fine-tuned PID parameters through systematic testing
• Added derivative term to reduce oscillation
• Implemented speed reduction during sharp turns

Challenge 3: Power Management

Problem: Battery life was insufficient for extended testing sessions.

Solution:

• Optimized code to reduce processing overhead
• Implemented sleep modes when stationary
• Added low-battery detection and warning system

Results and Performance

Quantitative Results

• Line Following Accuracy: 95% success rate on standard test track
• Speed: Average 0.5 m/s with smooth curves
• Battery Life: 45 minutes of continuous operation
• Response Time: <50ms for direction changes

Performance Video

Note: In a real portfolio, you would embed a video here showing your robot in action.

Key Learnings

Technical Skills Developed

1. Embedded Programming: Gained proficiency in C++ and Arduino development
2. Control Systems: Deep understanding of PID control theory and implementation
3. Sensor Integration: Experience with multiple sensor types and data fusion
4. Debugging: Systematic approach to hardware and software troubleshooting

Project Management Skills

1. Planning: Breaking complex projects into manageable milestones
2. Documentation: Importance of clear code comments and project logs
3. Testing: Systematic testing and validation procedures
4. Iteration: Continuous improvement based on testing results

Future Improvements

Short-term Enhancements

• Add wireless communication for remote monitoring
• Implement path planning for complex track layouts
• Integrate machine learning for adaptive behavior
• Add data logging for performance analysis

Long-term Vision

• Scale up to larger, more complex autonomous systems
• Explore SLAM (Simultaneous Localization and Mapping)
• Investigate multi-robot coordination
• Apply learnings to real-world autonomous vehicle projects

Resources and References

Helpful Links

• Arduino Official Documentation
• PID Control Theory
• Computer Vision Basics
• Robotics Stack Exchange

Recommended Reading

1. “Introduction to Autonomous Mobile Robots” by Siegwart & Nourbakhsh
2. “Programming Robots with ROS” by Quigley, Gerkey & Smart
3. “Robotics: Modelling, Planning and Control” by Siciliano et al.

Open Source Code

The complete source code for this project is available on my GitHub:

• Repository: github.com/username/line-following-robot
• License: MIT License
• Documentation: Full API documentation included

Conclusion

This autonomous robot project was an invaluable learning experience that bridged theoretical knowledge with practical implementation. The combination of mechanical design, embedded programming, and control systems provided a comprehensive introduction to robotics engineering.

The project not only achieved its technical objectives but also taught important lessons about project planning, systematic debugging, and the iterative nature of engineering design. These skills will be essential as I continue to tackle more complex robotics challenges.

What’s Next? I’m currently working on a computer vision-based object sorting robot that builds upon the concepts learned in this project. Stay tuned for updates!

Have questions about this project or want to collaborate on similar robotics projects? Feel free to reach out – I’d love to connect with fellow robotics enthusiasts!