Inch Worm

Submitted by fchasen on Wed, 03/20/2013 - 11:53

Description

I made several iterations with the same idea of a inch worm that crunchs and then expands to move. Getting the weight and pulling force right was difficult and different for every surface. Moving the servo motor to the back helped as did copious rub band pads.

Getting the speed right was also took some refining, but it crawls now - at least on some surfaces.

Components

  • Ardunio Uno
  • Bread Board
  • Servo Motor
  • Cardboard
  • Curtain ends
  • 9 quarters for weight
  • Paper mouth
  • wooden circles for eyes and weight
     

Code

 

/*
 * Inch Worm - Fred Chasen
 */
 
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 = 40;  // the time in millisecs needed in between pulses
int val;               // variable used to store data from potentiometer
 
int dir = 0;
int amt = 1;
 
int minPulse = 1200;   // minimum pulse width
int maxPulse = 2430;  // maximum pulse width
 
int crunchTime = 1000;
long lastCrunch = 0; 
 
void setup() {
  pinMode(servoPin, OUTPUT);  // Set servo pin as an output pin
  pulseWidth = maxPulse;      // 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);
//  
//  }
  
  
  
  
//  if (millis() - lastPulse >= refreshTime) {
//    if(val <= 1){
//    val = 8;
//  }
//  
//  if(val >= 8){
//    val = 1;
//  }
//  }
  
  //pulseWidth = (val * (maxPulse-minPulse) / 8) + minPulse;  // convert val to microseconds
  
  if (millis() - lastCrunch >= crunchTime) {
    
      if(pulseWidth == maxPulse){
        pulseWidth = minPulse;
      }else{
        pulseWidth = maxPulse;
      }
      
      lastCrunch = millis();
  }
  
  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
  }
}
 
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