increase and decrease speed as the servo moves

smoothly.ino

// Functional example to apply to servo motors to remove the aggressive way they moves. 
// Author: Rui Rigel https://github.com/ruirigel

#include <Servo.h>

Servo servo;

int SERVOPIN = 4;
int POS = 0;
int BUTTONPIN = 2; // to move the servo by alternating direction
int LEDPIN = 3; // on/off indicator
int msv = 50; // speed
int move_smoothly = msv;

void setup() {
  Serial.begin(9600);
  pinMode(LEDPIN, OUTPUT);
  digitalWrite(LEDPIN, HIGH);
  servo.attach(SERVOPIN);
  pinMode(BUTTONPIN, INPUT);
}

void loop() {
  if ((digitalRead(BUTTONPIN) == HIGH) && (POS > 179)) {
    servo.attach(SERVOPIN);
    for (POS = 180; POS >= 0; POS -= 1) {
      if (POS > 160) {
        move_smoothly = move_smoothly - 1;
        delay(move_smoothly);
      }
      if (POS < 160 || POS > 20) {
        delay(move_smoothly);
      }
      if (POS < 20) {
        move_smoothly = move_smoothly + 1;
        delay(move_smoothly);
      }
      servo.write(POS);
    }
    move_smoothly = msv;
    POS = 0;
    delay(1000);
    servo.detach();

  } else if ((digitalRead(BUTTONPIN) == HIGH) && (POS < 1)) {
    servo.attach(SERVOPIN);
    for (POS = 0; POS <= 180; POS += 1) {
      if (POS < 20) {
        move_smoothly = move_smoothly - 1;
        delay(move_smoothly);
      }
      if (POS > 20 || POS < 160) {
        delay(move_smoothly);
      }
      if (POS > 160) {
        move_smoothly = move_smoothly + 1;
        delay(move_smoothly);
      }
      servo.write(POS);
    }
    move_smoothly = msv;
    POS = 180;
    delay(1000);
    servo.detach();

  }

}