encoder counts

[Yahoo1]

Hello everyone,

I am doing some motion control and got some problems. If anybody could give me any advise, it is very appreciated.

I am using Baldor's products. AC servo motor with resolver, amplifier receives the reolver's signal and converts it to a simulated quadrature encoder signal then send it to controller. From the controller side, the resolution is 4096counts/revolution.
I want to track the position all the time, so I store the encoder counts number in memory on the controller in case the power off.
Then I kept the controller power on, cycle the amplifier power on and off. No any demand was send to amplifier. So the motor won't move. But everytime the encoder counts changed by a few hundreds counts and sometime around 2000 counts. The changing is bigger when power on the amplifier.
Is it because the vibration on the motor or the resolver send to digital device some spurious pulse when the power is cycled? Any solution for it?

Thank you very much for your answer in advance.

Wendy

 

[Barry1961]

I think you will have to get the absolute encoder option to do what you want. If there was an easy way the big robotic mfgs would be using it.

Barry

 

[avigodner]

To be exposed to sinusoidal brushless with incremental encoder power-on issues read Smart Initialization article overview at

http://www.drbrushless.com/cgi-bin/articles.phtml