Erratic Servo Movements

Hi all,

I picked up a little servo at the local Jaycar Electronics store. I'm controlling it with the standard Servo library. This is my first experience with a servo so I'm not sure if that this thing is doing is normal or not.

I've wired up some buttons to make the servo move 10 degrees clockwise with one button and 10 degrees anticlockwise. It performs the same function with repeated presses of the same button (so the servo should be receiving the same pulses each time).

Problem is, with one press forward, it might move 12 degrees, and the next press it'll move 8. Pressing backwards, it'll move back 12 degrees and then next press, the remain 8. Not exactly those figures, but you get what I mean. It seems like it's first move in the 'opposite direction' to its last move, is a big move and then those thereafter are correct.

I don't care if it moves 8 or 10 degrees, because I can tweak that. All I want is consistent moves in both directions. Is this normal behaviour or is this thing just a piece of junk?

I've uploaded a little movie to YouTube so hopefully you can see what I'm talking about: Servo Erratic Movements - YouTube

Pretty obvious at the 6 second mark. What do you reckon?

Cheers,
Scott

It is probably backlash in the servo pot. The first time you change the direction the motor is powered more to take up the slack in the feed back pot. After that all steps will be tthe same until you change direction again.

Solution is to spend more money on your servos. :frowning: