Description:
In this lab we used servo motors to turn rotational motion into linear motion.
This was challenging because the servo motors only rotate 180 degrees back and forth. I stuck the servo motor to a box within the lid of another box and attached a small piece of wood with a metal clip. In order to make the crawler move forward rather than step forward and backword repetitively, gaining no distance, I attached a small piece of thick tape to one end of the wood. This allowed the crawler to stick temporarily to the table, move itself forward, unstick and rotate up, rotate down and restick, etc. I had to put my keys in the lid of the box to prevent the crawler from toppling over because it was too lightweight. I used a pot to control the movement of the servo motor.
Link to the video
Components Used:
1- Arduino UNO
1- breadboard
1- pot
1- Servo Motor
1.5- small boxes
1- metal clip
1- weight (keys)
thick tape
wires
Code:
This code was provided in the lab.
/*
* 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
}
}
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