How to ramp (spindle) in galil open loop control

[lfleiva]

Hi to everyone,
I have a Galil board controlling a DC driver and spindle without encoder.  I do this by using the Galil in open loop mode (PID disabled: KD=KP=KI=0). 

The Galil does respond to the Mach3 speed control but I haven't been able to output the control signal with a ramp.  If I want full speed it will just instantaneously output the 10V to driver creating large overshoot.  Neither acceleration from Galil (AC,DC) nor the acceleration parameters in Mach3 Motor Tuning will respond. The driver has no way to control minimum ramp also.

Someone knows the solution?

Regards!
Luis

[NosmoKing]

AFAIK, without the encoder and the ability to set accel (AC) and use Jog command, you may have to set a progressive sequence of outputing a  torque limit ramp  (TL).
I usually use encoder for a spindle so I am just guessing at the solution.
Nosmo.

[lfleiva]

»You may have to set a progressive sequence of outputing a  torque limit ramp  (TL).

That's what I though Mach 3 could probably do. There's another way which is using the Offset command:  OF.

Anyway, I don't know how to do it myself either because I think it may imply modifying the Galil plugin.  I don't think it may be possible to do it with the custom notify messages.

Any other idea?

[kcrouch]

I think that you are better off implementing an RC circuit between the Galil and your motor drive. You could even use a potentiometer to vary the accel/decel rate.
Kenny

[lfleiva]

Thanks Kenny,
Great idea. That's a simple PD controller.

I will try that also, right now what I am doing is a small single encoder with an induction sensor to one of the spindle pulleys plus direction signal provided from Mach3.

Luis fdo.

[kcrouch]

The plugin uses the Galil OF command to control spindle speed. Even with an encoder, the spindle speed still uses the OF command. There is no accel or decel with the OF command, so I think that you will still need to use an RC circuit to get the type of control that you are looking for.