Getting servo to vibrate for a bit after movement

[ajkochev]

I'm trying to get a servo to vibrate slightly after it moves to a position. The servo can move from either direction. Use case is a little "bounce" or vibration on a model railroad semaphore signal just after it changes position.

The below function works but I feel it could be better. bouncePeriod will likely be 40. and bounceStep is usually 15.

void bounceRun (int curServo, int curPos, int typeMove)
{
    int m = curPos; int f = curPos;

    if (typeMove == 1)  {
      //Move two steps back
      delay(bouncePeriod[curServo]);
      m = m - bounceStep[curServo];
      pwm1.writeMicroseconds(curServo, m);
      delay(bouncePeriod[curServo]);
      m = m - bounceStep[curServo];
      pwm1.writeMicroseconds(curServo, m);
      //Move four steps forward
      delay(bouncePeriod[curServo]);
      m = m + bounceStep[curServo];
      pwm1.writeMicroseconds(curServo, m);
      delay(bouncePeriod[curServo]);
      m = m + bounceStep[curServo];
      pwm1.writeMicroseconds(curServo, m);
      delay(bouncePeriod[curServo]);
      m = m + bounceStep[curServo];
      pwm1.writeMicroseconds(curServo, m);
      delay(bouncePeriod[curServo]);
      m = m + bounceStep[curServo];
      pwm1.writeMicroseconds(curServo, m);
      //Move three steps back
      delay(bouncePeriod[curServo]);
      m = m - bounceStep[curServo];
      pwm1.writeMicroseconds(curServo, m);
      delay(bouncePeriod[curServo]);
      m = m - bounceStep[curServo];
      pwm1.writeMicroseconds(curServo, m);
      delay(bouncePeriod[curServo]);
      m = m - bounceStep[curServo];
      //Move two steps forward
      pwm1.writeMicroseconds(curServo, m);
      delay(bouncePeriod[curServo]);
      m = m + bounceStep[curServo];
      pwm1.writeMicroseconds(curServo, m);
      delay(bouncePeriod[curServo]);
      m = m + bounceStep[curServo];
      pwm1.writeMicroseconds(curServo, m);
    }
    if (typeMove == 2) {
      //Move two step forward                          
      delay(bouncePeriod[curServo]);
      m = m + bounceStep[curServo];
      pwm1.writeMicroseconds(curServo, m);
      delay(bouncePeriod[curServo]);
      m = m + bounceStep[curServo];
      pwm1.writeMicroseconds(curServo, m);
      //Move four steps back
      delay(bouncePeriod[curServo]);
      m = m - bounceStep[curServo];
      pwm1.writeMicroseconds(curServo, m);
      delay(bouncePeriod[curServo]);
      m = m - bounceStep[curServo];
      pwm1.writeMicroseconds(curServo, m);
      delay(bouncePeriod[curServo]);
      m = m - bounceStep[curServo];
      pwm1.writeMicroseconds(curServo, m);
      delay(bouncePeriod[curServo]);
      m = m - bounceStep[curServo];
      pwm1.writeMicroseconds(curServo, m);
      //Move three steps forward
      delay(bouncePeriod[curServo]);
      m = m + bounceStep[curServo];
      pwm1.writeMicroseconds(curServo, m);
      delay(bouncePeriod[curServo]);
      m = m + bounceStep[curServo];
      pwm1.writeMicroseconds(curServo, m);
      delay(bouncePeriod[curServo]);
      m = m + bounceStep[curServo];
      //Move two steps back
      pwm1.writeMicroseconds(curServo, m);
      delay(bouncePeriod[curServo]);
      m = m - bounceStep[curServo];
      pwm1.writeMicroseconds(curServo, m);
      delay(bouncePeriod[curServo]);
      m = m - bounceStep[curServo];
      pwm1.writeMicroseconds(curServo, m);
    }
    //Set final position to what is was at start of function and clear bounceNow trigger
    bounceNow [curServo] = 0;
    pwm1.writeMicroseconds(curServo, f);
}

[groundFungus]

The ServoEasing library may be of interest.

There is a bounce function that might do what you want.

[TomGeorge]

Hi, @ajkochev

Nice project.

Have you Googled;

bouncing railway semaphore arduino

Semaphore signal bounce using servo

Tom...