Smooth servo control library
Infortunately, I did not find any library but I found that the method shown below could work quite well for small projects. By adding a small delay, it helps the servo run a little smoother. It is not really ideal but it should work if your goal is to minimize the roughness of the servo.

Also by adding a 100uF capacitor between 5V and GND, the capacitor will help calm the sudden rush you might get when the servo first starts to turn. That rush is caused by the servo asking for more current when the servo is not moving.

#include &lt;Servo.h&gt;   //servo library
Servo myservo;       //servo object
int previousAngle = 0;

const int potPin = A3; //sensor pin

void setup() {
  myservo.attach(9);  //data pin of the servo
  pinMode(potPin, INPUT); //sensor pin as an input
}

void loop() {
  int val = analogRead(potPin);
  int angle = map(val, 0, 1023, 0, 180);

  if(angle&gt;previousAngle)
  {
    for(int i=previousAngle; i&lt;=angle; i++)
    {
      myservo.write(i); //turn servo by 1 degrees
      delay(10);        //delay for smoothness
    }
  }

  if(angle&lt;previousAngle)
  {
    for(int i=previousAngle; i&gt;=angle; i--)
    {
      myservo.write(i); //turn servo by 1 degrees
      delay(10);        //delay for smoothness
    }
  }

  previousAngle = angle;
}