🤖 Lesson 9: Programming Mechatronics

🎯 What is Mechatronics?

Simple Example: Robot vacuum cleaner

• Mechanical: Wheels, brushes, chassis
• Electronics: Sensors to detect walls, motors to spin wheels
• Software: Code that tells it when to turn, clean, or return to base

Real-World Applications NICE TO KNOW

💻 Microcontrollers vs CPUs MUST KNOW

Why Use Microcontrollers Instead of CPUs?

Hardware Requirements NICE TO KNOW

Key Concept: Microcontrollers have limited resources (memory, speed) compared to regular computers. This affects how you write code:

• Less RAM: Can't store huge amounts of data
• Slower Processing: Simple calculations only
• No Operating System: Your code runs directly on the chip
• Real-Time Operation: Responds immediately to sensor input (no delays from multitasking)

👀 Sensors: Input Devices MUST KNOW

Common Sensor Types

// Measure distance to an object
int trigPin = 9;
int echoPin = 10;

void setup() {
  pinMode(trigPin, OUTPUT);
  pinMode(echoPin, INPUT);
  Serial.begin(9600);
}

void loop() {
  // Send sound pulse
  digitalWrite(trigPin, HIGH);
  delayMicroseconds(10);
  digitalWrite(trigPin, LOW);

  // Measure time for echo to return
  long time = pulseIn(echoPin, HIGH);

  // Calculate distance (speed of sound = 343 m/s)
  int distance = time * 0.034 / 2;

  Serial.print("Distance: ");
  Serial.print(distance);
  Serial.println(" cm");

  delay(500);
}

💪 Actuators: Output Devices MUST KNOW

Common Actuator Types

End Effectors / Manipulators NICE TO KNOW

End Effector: The "hand" at the end of a robotic arm that interacts with objects.

• Grippers: Open/close to pick up objects (parallel jaw, adaptive fingers)
• Vacuum Grippers: Use suction to hold flat objects (glass, metal sheets)
• Magnetic Grippers: Use electromagnets for metal objects

#include <Servo.h>

Servo myServo;

void setup() {
  myServo.attach(9);  // Connect servo to pin 9
}

void loop() {
  myServo.write(0);    // Turn to 0 degrees
  delay(1000);
  myServo.write(90);   // Turn to 90 degrees
  delay(1000);
  myServo.write(180);  // Turn to 180 degrees
  delay(1000);
}

🔄 Control Systems MUST KNOW

Open Loop Control (No Feedback)

Pros: Simple, cheap, no extra sensors needed

Cons: Can't detect failures or adapt to changes

// Just blink LED, don't check if it's working
digitalWrite(LED_PIN, HIGH);
delay(1000);
digitalWrite(LED_PIN, LOW);
delay(1000);

Closed Loop Control (Feedback-Driven)

How It Works:

1. Set target (e.g., 21°C)
2. Read sensor (current temperature)
3. Compare: Is it too hot or too cold?
4. Adjust actuator (turn heater on/off)
5. Repeat constantly

Pros: Adapts to changes, can detect errors

Cons: More complex, requires sensors

// Robot that follows a black line on white surface
int leftSensor = A0;
int rightSensor = A1;

void loop() {
  int left = analogRead(leftSensor);
  int right = analogRead(rightSensor);

  // CLOSED LOOP: Check sensors and adjust
  if (left < 500 && right < 500) {
    // Both on black → go straight
    goStraight();
  } else if (left > 500) {
    // Left on white → turn left to find line
    turnLeft();
  } else if (right > 500) {
    // Right on white → turn right
    turnRight();
  }
}

🧠 Control Algorithms MUST KNOW

Autonomous Control

Simple Algorithm Pattern:

void loop() {
  // 1. SENSE: Read sensors
  int distance = readUltrasonicSensor();

  // 2. DECIDE: Determine action
  if (distance < 20) {
    // Obstacle detected
    action = TURN_RIGHT;
  } else {
    // Path clear
    action = MOVE_FORWARD;
  }

  // 3. ACT: Control actuators
  executeAction(action);
}

🛠️ Testing with TinkerCAD NICE TO KNOW

♿ Accessibility Design MUST KNOW

Design Considerations

Power and Battery Considerations NICE TO KNOW

Why it matters: Assistive mechatronic devices must have reliable power—running out of battery could be dangerous.

Key Considerations:

• Battery Capacity: How long can the device run? (measured in mAh)
• Power Requirements: Calculate total power draw from all components
• Backup Systems: Low battery warnings, backup batteries
• Charging: Easy-to-use charging ports, fast charging capability

🎯 HSC Exam Focus