1.7 Actuator Code Introduction

Congratulations on reaching this stage in your embedded systems tutorial! In this section, we'll discuss the actuator board code that controls a servo motor for opening and closing operations. This tutorial builds upon the fundamental concepts you've learned so far, including for loops, functions, and analog reading.

Actuator Board Functionality

The actuator board is designed to control multiple mechanisms, including a grabber, a dropper, and a torpedo. For now, we have physically implemented a grabber/dropper mechanism using a single servo. This functionality is critical for our competition, as we need to be able to physically grab and drop items underwater.

Code Explanation

Here's the simplified code for the actuator board:

#include <Servo.h>

#define CURRENT_PIN 16
#define SERVO_PIN 11

Servo servo1; // Create servo object to control a servo 

void setup() 
{ 
  Serial.begin(9600); // Initialize serial communication
  pinMode(CURRENT_PIN, INPUT); // Set current sensing pin as input
  servo1.attach(SERVO_PIN); // Attach the servo to the specified pin
} 

void loop() 
{
  // Call open and close functions as needed
  open_actuator();
  delay(2000); // Wait for 2 seconds

  close_actuator();
  delay(2000); // Wait for 2 seconds
}

// Function to close the actuator
void close_actuator() {
  for (int pos = 0; pos <= 180; pos += 1) { // Move from 0 to 180 degrees
    servo1.write(pos); // Move servo to position
    print_current(); // Print current reading
    delay(15); // Wait for servo to reach position
  }
}

// Function to open the actuator
void open_actuator() {
  for (int pos = 180; pos >= 0; pos -= 1) { // Move from 180 to 0 degrees
    servo1.write(pos); // Move servo to position
    print_current(); // Print current reading
    delay(15); // Wait for servo to reach position
  }
}

// Function to print the current reading
void print_current() {
  int currentReading = analogRead(CURRENT_PIN); // Read current
  Serial.println(currentReading); // Print current reading to the serial monitor
}

Key Components of the Code

Libraries:

We include the Servo.h library to simplify controlling the servo motor. Libraries provide pre-written code that helps streamline your projects. For more details on using libraries, check out this section.

Setup Function:

The setup() function initializes the serial communication for debugging and configures the pin modes. The servo is attached to a specified pin.

Loop Function:

The loop() function repeatedly calls the open_actuator() and close_actuator() functions, with a delay in between to allow the servo to complete its movements.

Open and Close Functions:

The open_actuator() and close_actuator() functions control the servo's movement from 0 to 180 degrees and vice versa. Each iteration prints the current reading to the serial monitor using the print_current() function.

Analog Reading:

The print_current() function uses analogRead() to read the current from a specified pin. This pin is essential because when the current reading is high, it indicates that the servo has closed, signaling that it’s time to stop sending commands to further close the servo. For more information on analog reading, refer to this section.

Conclusion

While this code is simplified, it serves as an abstraction of how the actuator board operates. At its core, we are controlling a servo motor and telling it to open and close, allowing us to manipulate objects effectively. As you progress, you'll encounter more complex functions and systems, but understanding these basics will give you a solid foundation for future challenges. If you have any questions or need assistance, please reach out to a lead or senior member of the team.

Happy coding!