Assignment: Servo Motor: Actuation Assignment 2
Collaborators:
Materials
Design: This crawling bot uses one servo motor to move. It crawls forward by wiggling its front legs and backside, creating an alternating pattern that drives it forward. The inspiration for the design came from the wave-board, a two-wheeled skate board that uses simple wiggle motion to move forward.
Problems: My crawler enjoyed falling down as much as it did moving forward. Balance and friction were my two main issues. The balance problem is not really solved. If I move the potentiometer too far in either direction, the crawler will lose its balance. I created friction for the crawler's legs by moving adding rubber bands to its "feet".
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 } }