How do the servos work?

[Mike Soukup]

Originally Posted by zainali

We don't want the servo to rotate more then it is doing right now.But we were wondering if servos can be made to rotate backwards. This is because everytime you make it turn you have to manually twist it back to its starting position to make it turn again.

I think you first need to understand how a servo behaves. Unlike a motor, you do not give a servo a speed, you give it a position. If you directly map a motor to the y-axis of a joystick and push the stick half way forward, the motor will run at half speed until you release the stick, then it will stop. If you do the same with a servo, it will rotate half way to one end and stay there, then when you release the stick it will return to the middle. The servo is actually a motor and a potentiometer all in one, it performs the whole feedback loop for you. You give the servo a position (from 0-255) and it goes to that position and stays there until you give it a new position. They're actually pretty cool little devices.