Servo motors are actuators that allow the precise control of the angle of the axel. Typical servo motors are constructed from a regular DC motor, combined with a gear ratio, potentiometer to measure the final position of the axel some digital components to control the motor. Most servo motors are limited to a certain range of angles, often between 0 and 180 degrees.
Common types of hobby servos read PWM signals and convert this into angles. The easiest way to generate the correct PWM signal for a given angle is to use the Servo library in Arduino.
#include <Servo.h>
Servo myservo; // create servo object
int pos = 0; // variable to store the servo position
void setup() {
myservo.attach(9); // attaches the servo on pin 9 to the servo object
}
void loop() {
for (pos = 0; pos <= 180; pos += 1) { // goes from 0 degrees to 180 degrees
// in steps of 1 degree
myservo.write(pos); // tell servo to go to position in variable 'pos'
delay(15); // waits 15ms for the servo to reach the position
}
for (pos = 180; pos >= 0; pos -= 1) { // goes from 180 degrees to 0 degrees
myservo.write(pos); // tell servo to go to position in variable 'pos'
delay(15); // waits 15ms for the servo to reach the position
}
}
We can also add some easing, to smooth out the movements of the servo and achieve a more organic movement. The algorithm used here is the same seen in Signal Filtering.
#include <Servo.h>
Servo myservo; // create servo object to control a servo
int angle = 160; // goal angle of servo
float easedAngle; // for storing an eased position between current and goal angle
int lastChange; // Used for timing changes of angle
void setup() {
myservo.attach(9); // attaches the servo on pin 9 to the servo object
Serial.begin(9600);
}
void loop() {
// change the goal angle every 5000 miliseconds
if (millis()>= lastChange+5000) {
lastChange = millis();
if (angle == 160) {
angle = 20;
} else {
angle = 160;
}
}
easedAngle = angle*0.02 + easedAngle*0.98;
Serial.print(angle);
Serial.print(",");
Serial.println(int(easedAngle));
myservo.write(easedAngle);
delay(10);
}