Tangible User Interfaces - Fall 2011

Description:

This mash up of a wooden cat and office supplies is my implementation of a forward walker. The greatest challenge was balancing the weight such that the cat would move forward (for the most part) without twisting in circles.  This was accomplished by taping the binder clip on as a guide and taping another nickel on it for weight.  I used a roll of electrical tape for a wheel and made it hit the ground by adding furniture pads.  Inspired by the example given in class.  I used a rubber band to facilitate forward movement and hinder backward movement.  Movement of the servo motor is controlled by the potentiometer. 

Materials:

• 1 x Roll electrical of tape
• 1 x Nickel
• 1 x Servo Motor
• 1 x Binder Clip
• 1 x Wooden Cat
• 1 x Rubber Band
• 1 x Sticky Cotton Furniture Pads
• 1 x Potentiometer

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
  }
}