The Faux Shaux

My intention was to use a servo motor to rattle a snake tail necklace that I have.  I envisioned a shoe-box marked “DANGER” that hid an ultra-sonic sensor, which upon detecting the close proximity of a curious ITP student, would rattle the tail.

I couldn’t find my snake necklace, so I fashioned a rattle from some plastic tubing, lamp chain & wood scraps (oops, Sara I still have your green screwdriver).  This fabrication took abnormally long since the screw for the servo attachments does not like to thread tightly, and after a very long series of trials and errors, I just hot-glued the dang thing.

shake it like a polaroid

Here is the code for the prototype with a potentiometer instead of the ultrasound.

int servoPin = 5;     // Control pin for servo motor

int minPulse = 500;   // Minimum servo position

int maxPulse = 2500;  // Maximum servo position

int pulse = 0;        // Amount to pulse the servo

 long minValue;

 long maxValue;

 int midValue=1400;

// flag to determine if we should be constantly moving

long lastSensorReading = 0;

long lastPulse = 0;    // the time in milliseconds of the last pulse

int refreshTime = 20; // the time needed in between pulses

int analogValue = 0;  // the value returned from the analog sensor

int analogPin = 0;    // the analog pin that the sensor's on

void setup() {

 pinMode(servoPin, OUTPUT);  // Set servo pin as an output pin

 pulse = midValue;           // Set the motor position value to the minimum

 Serial.begin(9600);

}

void loop() {

 analogValue = analogRead(analogPin);      // read the analog input

 minValue = 1300 - ((700*analogValue)/1023);

 maxValue = 1500 + ((700*analogValue)/1023);

 Serial.print("minVal: ");

 Serial.print(minValue, DEC);

 Serial.print(" maxVal: ");

 Serial.println(maxValue, DEC);

 // pulse the servo again if the refresh time of 20 ms has passed:

 if (millis() - lastPulse >= refreshTime) {

    // check the force sensor every second

    int accel = map(analogValue, 0, 1023, 100, 500);

    if (millis() - lastSensorReading >= accel) { //SPEED

       Serial.println(analogValue);

       // if we are still reading a high value from the pressure sensor,

       // determine the next position of the servo motor

      // if (analogValue > 400) {

         // if (pulse >= 2200)

       //    { pulse = 600; } // TWO POSITIONS

         // else { pulse = 2200; }

          if (pulse >= maxValue) { pulse = minValue; } // TWO POSITIONS

          else { pulse = maxValue; }

         // }

      lastSensorReading = millis();

      }

    //Serial.println(pulse);

    // tell the servo motor to move to it's new position

    digitalWrite(servoPin, HIGH);      // Turn the motor on

    delayMicroseconds(pulse);       // servo moves to new locale

    digitalWrite(servoPin, LOW);       // Turn the motor off

    lastPulse = millis();           // save the time of the last pulse

    }

  }