Assignment: Servo Motor: Actuation Assignment 2

Collaborators:

Well, it does not quite "Crawl" but it moves around in a fun and interesting way. For this lab, we learned how to use servo motors to control movement more precisely than with just a regular motor. I was having a hard time thinking of a way to make something crawl with just one actuator. i started off with some pipe-cleaner that I had from an earlier project. Turns out that the pipe-cleaner is strong enough to move the motor. I teamed that up with a Brown cow yogurt container I had just finished eating out of. After a good wash with soap, and some duct tape, I got the little servo motor to push the cup over. One of the problems is with balance, because the cup is really easy to tip over. I tried fixing that with an extra tail made out of pipe cleaner. My last problem was with friction. The bristles on the pipe cleaner do not provide enough friction against my smooth desk, so i added a rubber band to give it a little extra friction. 

The programming code I used involved a Pot controlling the Servo Motor. By moving the Pot back and forth over a small range, you can get the cup to move around.

Items used:

1 yogurt container

1 Pot

1 servo

2 Pipe cleaners

Wire

Arduino board

Code:

/*

 * Servo with Potentiometer control

 * Theory and Practice of Tangible User Interfaces

 * October 11 2007

 */

int servoPin = 7;      // Control pin for servo motor

int potPin   = 0;      // select the input pin for the potentiometer

int pulseWidth = 0;    // Amount to pulse the servo

long lastPulse = 0;    // the time in millisecs of the last pulse

int refreshTime = 20;  // the time in millisecs needed in between pulses

int val;               // variable used to store data from potentiometer

int minPulse = 500;   // minimum pulse width

void setup() {

  pinMode(servoPin, OUTPUT);  // Set servo pin as an output pin

  pulseWidth = minPulse;      // Set the motor position to the minimum

  Serial.begin(9600);         // connect to the serial port

  Serial.println("servo_serial_better ready");

}

void loop() {

  val = analogRead(potPin);    // read the value from the sensor, between 0 - 1024

  if (val > 0 && val <= 999 ) {

    pulseWidth = val*2 + minPulse;  // convert angle to microseconds

    Serial.print("moving servo to ");

    Serial.println(pulseWidth,DEC);

  }

  updateServo();   // update servo position

}

// called every loop(). 

void updateServo() {

  // pulse the servo again if rhe refresh time (20 ms) have passed:

  if (millis() - lastPulse >= refreshTime) {

    digitalWrite(servoPin, HIGH);   // Turn the motor on

    delayMicroseconds(pulseWidth);  // Length of the pulse sets the motor position

    digitalWrite(servoPin, LOW);    // Turn the motor off

    lastPulse = millis();           // save the time of the last pulse

  }

}