# Baby Steps

Description
My servo crawls with the help of a putty foot. The ball of its foot propels it forward when I rapidly rotate the pot by a small angle. The putty holds the “leg” together but also does not constrict the range of motion. It can only be rotated by a small angle only because it won’t otherwise it will go backwards.

Materials
Drill, Putty, Metal Hex, Tape, Toothpick
Clothespin
Servo, Servo Container, Potentiometer
``` /* * 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 } } ```