571 Actuator Hands-On Labs

Learning Objectives

After completing these labs, you will be able to:

Build complete actuator control systems from scratch
Interface multiple actuator types in a single project
Implement coordinated motion control
Use Wokwi simulations for testing before hardware deployment
Troubleshoot common actuator problems

571.1 Lab 1: DC Motor Control with L298N

Objective: Control a DC motor using the L298N H-bridge driver with smooth acceleration and deceleration.

Materials:

ESP32 development board
L298N motor driver module
6V DC motor
9V power supply (for motor)
Jumper wires

Circuit Diagram:

ESP32          L298N         DC Motor
GPIO26 ------> IN1
GPIO27 ------> IN2
GPIO14 ------> ENA (PWM)
GND ----------> GND --------> Motor GND
               +12V --------> Motor VCC (from external PSU)
               OUT1 --------> Motor +
               OUT2 --------> Motor -

Code:

#define MOTOR_IN1 26
#define MOTOR_IN2 27
#define MOTOR_EN 14

const int pwmFreq = 5000;
const int pwmChannel = 0;
const int pwmResolution = 8;

void setup() {
  Serial.begin(115200);

  pinMode(MOTOR_IN1, OUTPUT);
  pinMode(MOTOR_IN2, OUTPUT);

  ledcSetup(pwmChannel, pwmFreq, pwmResolution);
  ledcAttachPin(MOTOR_EN, pwmChannel);

  Serial.println("DC Motor Controller with Ramping");
}

void loop() {
  Serial.println("Accelerating forward...");
  rampSpeed(0, 255, true, 50);
  delay(2000);

  Serial.println("Decelerating to stop...");
  rampSpeed(255, 0, true, 50);
  delay(1000);

  Serial.println("Accelerating backward...");
  rampSpeed(0, 255, false, 50);
  delay(2000);

  Serial.println("Decelerating to stop...");
  rampSpeed(255, 0, false, 50);
  delay(1000);
}

void rampSpeed(int startSpeed, int endSpeed, bool forward, int delayMs) {
  int direction = (endSpeed > startSpeed) ? 1 : -1;

  if (forward) {
    digitalWrite(MOTOR_IN1, HIGH);
    digitalWrite(MOTOR_IN2, LOW);
  } else {
    digitalWrite(MOTOR_IN1, LOW);
    digitalWrite(MOTOR_IN2, HIGH);
  }

  for (int speed = startSpeed;
       direction > 0 ? speed <= endSpeed : speed >= endSpeed;
       speed += direction * 5) {
    ledcWrite(pwmChannel, speed);
    Serial.print("Speed: ");
    Serial.println(speed);
    delay(delayMs);
  }

  ledcWrite(pwmChannel, endSpeed);
}

Expected Learning Outcomes:

Understand H-bridge operation for bidirectional motor control
Implement PWM speed control
Create smooth acceleration/deceleration profiles

571.2 Lab 2: Servo-Based Robotic Gripper

Objective: Build a 2-DOF robotic arm with gripper using servo motors and coordinated motion.

Materials:

ESP32 development board
3x SG90 or MG90S servo motors
5V 2A power supply
Breadboard and jumper wires

Power Supply Warning

Do NOT power multiple servos from the ESP32 5V pin! Use an external 5V 2A power supply. Connect ESP32 GND to power supply GND (common ground).

Circuit Diagram:

ESP32          Servos
GPIO18 ------> Base Servo (Signal)
GPIO19 ------> Arm Servo (Signal)
GPIO21 ------> Gripper Servo (Signal)
GND ----------> All Servo GND
5V ------------> All Servo VCC (from external PSU, NOT ESP32 5V!)

Code:

#include <ESP32Servo.h>

Servo baseServo;
Servo armServo;
Servo gripperServo;

#define BASE_PIN 18
#define ARM_PIN 19
#define GRIPPER_PIN 21

struct Position {
  int base;
  int arm;
  int gripper;
};

void setup() {
  Serial.begin(115200);

  baseServo.attach(BASE_PIN);
  armServo.attach(ARM_PIN);
  gripperServo.attach(GRIPPER_PIN);

  moveToPosition({90, 90, 90}, 1000);

  Serial.println("Robotic Gripper Ready");
  Serial.println("Commands: h=home, g=grab, r=release, s=sequence");
}

void loop() {
  if (Serial.available()) {
    char cmd = Serial.read();

    switch(cmd) {
      case 'h':
        Serial.println("Moving to home position");
        moveToPosition({90, 90, 90}, 1500);
        break;

      case 'g':
        Serial.println("Grab sequence");
        grabSequence();
        break;

      case 'r':
        Serial.println("Release sequence");
        releaseSequence();
        break;

      case 's':
        Serial.println("Pick and place sequence");
        pickAndPlace();
        break;
    }
  }
}

void moveToPosition(Position target, int duration) {
  int currentBase = baseServo.read();
  int currentArm = armServo.read();
  int currentGripper = gripperServo.read();

  int steps = duration / 20;

  for (int i = 0; i <= steps; i++) {
    float progress = (float)i / (float)steps;

    baseServo.write(currentBase + (target.base - currentBase) * progress);
    armServo.write(currentArm + (target.arm - currentArm) * progress);
    gripperServo.write(currentGripper + (target.gripper - currentGripper) * progress);

    delay(20);
  }
}

void grabSequence() {
  moveToPosition({90, 45, 90}, 1000);
  delay(500);
  moveToPosition({90, 45, 45}, 800);
  delay(500);
  moveToPosition({90, 90, 45}, 1000);
}

void releaseSequence() {
  moveToPosition({90, 45, 45}, 1000);
  delay(500);
  moveToPosition({90, 45, 90}, 800);
  delay(500);
  moveToPosition({90, 90, 90}, 1000);
}

void pickAndPlace() {
  Position home = {90, 90, 90};
  Position pickPos = {45, 45, 90};
  Position pickGrab = {45, 45, 45};
  Position placePos = {135, 45, 45};
  Position placeRelease = {135, 45, 90};

  moveToPosition(pickPos, 1500);
  delay(500);
  moveToPosition(pickGrab, 800);
  delay(500);
  moveToPosition(placePos, 2000);
  delay(500);
  moveToPosition(placeRelease, 800);
  delay(500);
  moveToPosition(home, 1500);
}

571.3 Lab 3: Multi-Actuator Control System

This lab combines multiple actuator types in a single project.

571.3.1 Wokwi Simulation

571.3.2 About the Components

Component	Type	Control Method	Function
Servo Motor	Position	PWM (50Hz, 1-2ms pulse)	Angle control
DC Motor	Speed	PWM (5kHz) + Direction	Variable speed
RGB LED	Visual	3x PWM channels	Color mixing
Buzzer	Audio	Tone frequency	Sound alerts

571.3.3 Challenges

Challenge 1: Traffic Light Controller (Beginner)

Create a traffic light using the RGB LED:

Red for 5 seconds
Yellow for 2 seconds
Green for 5 seconds
Yellow for 2 seconds
Repeat

Add a buzzer beep when changing to green (pedestrian signal).

Challenge 2: Speed-Responsive Motor (Intermediate)

Use a potentiometer to control:

DC motor speed (0-100%)
LED brightness (proportional to speed)
Buzzer pitch (higher = faster)

Challenge 3: Smart Fan Controller (Advanced)

Implement a temperature-responsive fan:

Read temperature from sensor (or simulate with potentiometer)
Below 20C: LED blue, motor off
20-25C: LED green, motor 50%
25-30C: LED yellow, motor 75%
Above 30C: LED red, motor 100%, alarm buzzer

571.4 Lab 4: Advanced PID Control

This lab implements PID feedback control for precise motor speed regulation.

571.4.1 Learning Objectives

Understand PID controller theory and tuning
Implement encoder feedback for closed-loop control
Debug control loop issues using Serial Monitor

571.4.2 Key Concepts

Proportional Term (P):

Output = Kp x Error

Responds to current error. Higher Kp = faster response but may overshoot.

Integral Term (I):

Output = Ki x Integral(Error)

Eliminates steady-state error. Higher Ki = faster correction but may oscillate.

Derivative Term (D):

Output = Kd x Derivative(Error)

Dampens oscillations. Higher Kd = more stability but sensitive to noise.

571.4.3 Tuning Guide

Start with Kp = 1, Ki = 0, Kd = 0
Increase Kp until system oscillates
Reduce Kp by 50%
Add Ki to eliminate steady-state error
Add Kd if oscillations occur

571.5 Troubleshooting Guide

Problem	Possible Cause	Solution
Motor doesn’t spin	Wrong wiring	Check IN1, IN2, and EN connections
Motor only spins one direction	Direction pins swapped	Swap IN1 and IN2
Servo jitters	Insufficient power	Use external 5V supply
Stepper skips steps	Acceleration too fast	Reduce max speed, increase acceleration time
Driver overheats	Current too high	Add heatsink, reduce motor current
Random resets	Missing flyback diode	Add diode across inductive loads

571.6 What’s Next?

Now that you’ve completed the hands-on labs, test your knowledge with the assessment chapter.

Continue to Assessment →