Lab 7 - Servo Motor a.k.a Yellow Submarine
Description
Use a servo motor to create a crawler that can move forward.
For this assignment, I used the popular "hobble forward" technique. After taping the servo motor on top of a small jewelry box, I attached a bendable drinking straw as a leg, which was able to move the entire contraption perpendicular to the motion of the drinking straw leg. I controlled the rotation and speed of the "leg" using a potentiometer. The crawler's drinking straw leg reminds me a little bit of a submarine periscope, hence the name of this assignment.
Ariel and I explored several other orientations and combinations of servo motors to produce motion, so be sure to check out those videos too! (Niranjan: the other videos are available here)
Components Used
- Arduino x 1
- Breadboard x 1
- wires x several
- potentiometer x 1
- servo motor x 1
- bendable drinking straw
- small yellow jewelry box
- black electrical tape
Code
I used the sample code "servo_control_pot.txt" from lab for this assignment.
/*
* 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
}
}
Video
Creator Comments
We all live in a yellow submarine.
