Re: [CAD_CAM_EDM_DRO] Re: Need help with servo power supply design

John Rouche wrote:

>Ok Jon, I need some educatin. I was under the impression the geckos
>made a full 60v available to the motor always with every step
>command.. Now I see I am wrong.
>
>

In a sense it does, but only for microseconds at a time. It applies the
DC supply
voltage, for a measured time, first one polarity and then the other.
When the motor
is not supposed to be moving or generating torque, the + and - polarity
balance exactly. That is the same as no voltage across the motor, except
for a little heating. This happens 25,000 times a second.

>How does the gecko know when to give full voltage? I thought it only
>interpreted step and direction commands not speed also.
>

It compares commanded velocity to actual velocity in a way. It uses analog
circuits to compare relative position (commanded vs. actual) and then
compares the long term error (the Integral term of PID) and the short term
change in error (the Derivative term) and computes how much torque to
demand from the motor. This sets the pulse width applied to the motor.

Jon