PID-Controlled One-Axis Ball Balancing System

PID-based one-axis ball balancing robot using Arduino. Uses an ultrasonic sensor and servo motor to stabilize a ball at a target distance. Real-time tuning of Kp, Ki, Kd via Serial. Includes stability detection and automatic neutral reset. The system stabilizes within 30s using empirically tuned parameters.

---

🖼️ Project Overview

---

🧪 Final Project Hardware

---

✨ Features

• PID Control for dynamic stability.
• Real-time sensor feedback using IR or ultrasonic sensors.
• Servo motor-driven beam for accurate actuation.
• Low-cost microcontroller implementation (Arduino/STM32).
• Serial Monitor & LCD integration for live debugging.

---

🛠️ System Architecture

---

📽️ Demo

Watch the demo video

---

🔌 Circuit Diagram

---

🧾 Project Summary

This Arduino-based system controls the position of a ball on a beam using PID control and real-time feedback from an ultrasonic sensor. The ball is returned to a setpoint by tilting the beam via a servo motor, compensating for positional error.

---

⚙️ How It Works

1. Sensing: Ball position is measured using HC-SR04.
2. Filtering: Distance values are filtered (moving average).
3. Error Calculation: error = distance - setpoint
4. PID Control:
   • P: Immediate reaction to error
   • I: Compensates for past errors
   • D: Predicts upcoming trends
5. Servo Adjustment: Beam angle is changed proportionally to the PID output.
6. Stability Monitoring: If error stays < 3 cm for 2.5 seconds, servo resets to neutral.

---

🧠 Control Strategy

A classic PID (Proportional-Integral-Derivative) loop is implemented:

Error = Desired Position - Actual Position  
PID Output = Kp * Error + Ki * ∫Error + Kd * (dError/dt)

Final tuned values:

• Kp = 5
• Ki = 0.01
• Kd = 9

Main Code Logic

error = distance - setpoint;
integral += error;
derivative = error - previous_error;
output = -(Kp * error + Ki * integral + Kd * derivative);
servoAngle = constrain(neutralAngle + output * 1.2, 0, 180);
myServo.write(servoAngle);

• PID gains can be tuned via Serial commands.
• System resets to neutral if error stabilizes or ball goes out of range.

---

🧪 PID Tuning via Serial Monitor

Kp 5         → Set proportional gain  
Ki 0.01      → Set integral gain  
Kd 9         → Set derivative gain  
neutral 34   → Set neutral servo angle  
servo -20    → Move servo from neutral

---

🔩 Hardware Components

Component	Description
Beam	30–50 cm acrylic/wood beam, pivot-mounted
Ball	Lightweight ping-pong ball
Servo Motor	SG90 (light load) or MG996R (high torque)
Position Sensor	- IR (GP2Y0A21) for analog - Ultrasonic (HC-SR04) for digital timing
Microcontroller	- Arduino Uno (simple) - STM32 Blue Pill (faster)
Power Supply	5V via USB or external battery pack
Optional Display	16x2 I2C LCD (PID values, position, error)
Accessories	Breadboard, jumpers, brackets, bearings, screws, etc.

---

📁 Repository Contents

• PID-Controlled-One-Axis-Ball-Balancing-System.ino – Core Arduino code
• Project_Proposal.pdf – Initial planning
• Project_Presentation.pptx – Final presentation
• Project_Report.pdf – Detailed documentation
• Demo Video.mp4 – Final working demo
• Cicuit Diagram.jpg – Wiring reference (check spelling)
• Project Picture.jpg – Setup image

---

🧰 Tech Stack

• Arduino Uno
• HC-SR04 Ultrasonic Sensor
• SG90 Servo Motor
• Serial Monitor for real-time control
• PID control logic (manual tuning)

---

✅ Results

• System stabilized within 30 seconds of a disturbance
• PID parameters: Kp = 5, Ki = 0.01, Kd = 9
• Stability detection reduces unnecessary movement

---

🚀 Future Enhancements

• 2-axis (X-Y) balancing system
• Vision-based tracking using OpenCV or IR grid
• Self-tuning PID or ML-based control
• Wireless monitoring via Bluetooth/Wi-Fi
• MATLAB or Python-based simulation-first approach

---

👨‍💻 Authors

This project was created at National University of Sciences & Technology (NUST) as part of the Linear Control Systems course project by:

• Awais Asghar
• Muhammad Ashar Javid
• Ameer Hamza
• Muhammad Hammad Sarwar

---

📜 License

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

---

📚 References

• Åström & Hägglund, Advanced PID Control, ISA
• Ogata, Modern Control Engineering, Pearson
• Arduino PID Library
• MathWorks MATLAB Control Toolbox