Servo Motors Workshop

Introduction

• Focus: Using servo motors with Arduino
• Covered Items: Basic operation, PCA 9685 module for controlling multiple servos

Overview of Motors

• Types of Motors Covered
  • Stepper Motors (previously covered in-depth)
  • DC Motors (used in robot car designs)
  • H-Bridge Modules (L298N for DC motors)
  • Servo Motors (focus of today, both analog and continuous rotation)

Servo Motors Basics

• Analog Servo Motor
  • Uses: Robotics, IoT projects, moving sensors/cameras
  • General Specs: 3 leads (GND, Power, Control)
  • Common Models: SG90 (plastic gears), HS-422 (higher torque)
• Continuous Rotation Servo Motor
  • Modded for continuous 360-degree rotation
  • Control: Adjust center point for stopping& rotation speed

Internal Mechanism

• Components
  • DC Motor internally
  • Potentiometer for shaft position feedback
  • Internal controller board adjusts shaft position using PWM
• PWM Control
  • Pulse width determines shaft position (e.g., 1.5 ms = 90°, 1 ms = 0°, 2 ms = 180°)
  • Analog servos typically have 180-degree range

Speed and Torque

• Definitions
  • Speed: Time to move shaft by 60° (e.g., 0.25 sec/60°)
  • Torque: Force applied to lever (e.g., 5 kg-cm)
• Specifications
  • Stall Torque: Torque that causes motor to stall
  • Peak Torque: Max torque for short periods
  • Rated Torque: Max torque at rated speed

Testing Servo Motors

• Tester Device
  • Connect servo to tester device to control shaft position
  • Various modes: manual control, 90-degree centering, sweep mode

Arduino Experiments

First Experiment: Servo Sweep Sketch

• Setup
  • Use separate power supply for servo (avoid using Arduino 5V)
  • Connect servo ground to Arduino ground, servo power to power supply, and servo control to Arduino pin 9
• Code (Sweep Sketch)
  • Libraries: Servo library included in Arduino IDE
  • Functions: Attach servo to pin, for loop to sweep from 0° to 180° and back

Second Experiment: Servo Control with Potentiometer (Knob Sketch)

• Additional Component: 10K+ potentiometer
• Setup
  • Connect potentiometer ends to Arduino 5V and ground, wiper to analog pin A0
• Code (Knob Sketch)
  • Functions: Analog read potentiometer, map value to servo angle, use servo.write() to position servo

Experiment: Multiple Servo Motors with PCA 9685

• Module Overview
  • Controls 16 PWM devices (servo or LEDs)
  • Uses I2C bus (clock and data lines)
  • Configurable via solder pads
  • Separate power supply for servos/LEDs
• Setup
  • Connect multiple servos, use I2C to control all via Arduino
  • Power PCA 9685 with separate supply, connect servos, and potentiometers
• Code
  • Library: Adafruit PWM Servo Driver Library
  • Functions: Map potentiometer read values to servo control signals

Key Recommendations

• Use separate power supply for servo motors to prevent noise and power spikes affecting Arduino
• Utilize external PWM control boards like PCA 9685 for multiple servo motor projects

Additional Resources

• Complete code and details available on the corresponding article on the workshop website
• Subscribe to the workshop newsletter for updates and project ideas

Conclusion

• Encouragement to utilize servo motors in projects
• Invitation to share project ideas
• Instructions to subscribe to YouTube channel and newsletter