Rotation angle of Servo???

[ecaits]

I am using Vigor VS 2 servo. As per data sheet, its output angle is >=170 degree and pulse traveling 800 to 2200 μsec.

When I give command of 90 degree to rotate, it rotate slightly more than 90 degree but when I give command of 85 degree then it is looking like exact 90 degree.

I have written simple program as written below.

Servo myservo;
int pos = 0;
void setup()
{
myservo.attach(9);
}
void loop()
{
myservo.write(85);
}

What I require to modify to get the exact angle as per program code.

Thank You,

Regards,
Nirav
 

[cyberjeff]

I'm going to broaden this a bit as I think this may be helpful to other.

So, where you servo winds up at is determined by a variety of factors, how the horn is mounted and how the servo is mounted among them. That and cheap servos are not perfect devices.

When you feed a servo, you want to adjust for that and also constrain it from travelling where it should not go (so it doesn't stall or break).

int desiredValue = 90;

int constrainMin = 30;
int constrainMax = 150;
int offset = -5;

int servoValue = constrain(desiredValue + offset, constrainMin, constrainMax);

myserveo.write(servoValue);

HTH