Servo Motor Gravity

There are many ways to get the servo to move forward. The method i settled on, was attaching it onto a disc and then a roll of tape so that it could stand up by itself. I found this setup interesting because it doesnt directly use the spinning of the 4-pointed-wheel to propel itself. Instead, it uses the gravity to pull itself forward. When spinning the potentiometer, the servo motor spins and causes the wheel to move forward in order to catch its balance. 
MATERIALS
1- arduino
1- potentiometer
1- servo motor
1- breadboard
1- tape roll
1- paper circle
CODE 
(unchanged)

/*

 * 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 the refresh time (20 ms) has 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

  }

}