[ynneb]

I have just taken delivery of my servos and am wondering how the servos hold their position.

There are just two wires that drive the servo, and all the encoder wires. I can understand how with the 2 drive wires you can forward and reverese the servo but how does it actually hold its position electrically. My only theory is that the driver will pulse the servo back and forth rapidly to hold the position. Is this correct?
I am doubting this theory because I can imagine that would make the servos vibrate, therefore causeing a jagged movement on the whole machine.

Does any one have an electrical explanation?

[Al_The_Man]

Benny, Simply put the control reads any servoing error by virtue of the encoder feedback and sends the appropriate correction signal, whether or not the servo 'vibrates' or is slow responding is all to do with the system/amplifier tuning. When the tuning is correct, the following error is at a minimum, over correction or too much gain in the system causes oscillation. Some sophisticated software systems have a built in oscilloscope screen whereby you can visually tune the servo's.
Al