Scissor Walk

Description
In this exercise we experimented with a servo motor controlled by the Arduino and a potentiometer. The servo motor only has a 180 degree range of circular motion making forward motion challenging. Our homework assignment was to find a way to create this forward motion using the motor. The main trick in creating forward motion is for the device to use the leverage in one direction, but not the other. For my homework I hooked up a pair of scissor to the servo motor, which created decent forward motion when adjust to the right height. The front leg of the scissor presses against the ground to create forward motion when closing, and then opens freely allowing further forward motion with additional turns of the motor. 
 
Materials
Materials
1- Arduino Uno
1- Futaba S3003 servo motor
1- potentiometer
1- motor box 
1- tape
1- scissors 
 
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 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

  }

}