Re: [CAD_CAM_EDM_DRO] Re: Pico VS IMService???

kdntool wrote:

>Jon,
>Please let me know if I am understanding correctly. With your USC
>board you can create a "pseudo-servo" system if you install encoders
>on the steppers?
>

It is "pseudo-servo" withOUT encoders. With encoders, it meets the true
definition of a servo system, by actually responding to and correcting
errors.

> The USC board has onboard rate generators to
>eliminate any possible host computer timing "bugs"?(takes the host
>out of the equation?)
>

Essentially, yes. The host computer is still responsible for acceleration,
trajectory, and keeping the actual position as close to the commanded as
possible. But, the timing of the individual step pulses is handled by
high resolution counters in the FPGA.

> You mentioned using a 4th axis "channel" to
>generate PWM for spindle speed control. Could you elaborate on this.
>Is it possible with EMC,could you use say 5th 6th or 7th and still
>retain the 4th axis for rotary motion?
>

EMC likes to have it's motion axes consecutive, so you send the spindle
speed to the first unused axis. Each USC board handles 4 axes, and it is
designed to permit daisy chaining of up to 4 board on one parallel port.

> Can I use drives other than
>Gecko or Rutex (say Xylotex) and still utilize the encoder feedback?
>
>

In theory, you can use anything that takes step and direction signals at
5 V levels. (The board also can generate phase signals for drives that
are lacking the forward/reverse direction signal.) A stepper drive that
is unaware of the servo loop should still work fine.

Please note that the use of the encoder allows the computer to DETECT
a stepper stall, but doesn't give it any capability to "unstall" the motor.
If the motor does manage to get back out of a stalled state before the
following error limit is reached, then it will correct the position and
continue. But, if the motor really stalls for a number of steps, the
computer will call for an e-stop. That is still better than continuing
blindly on after the position registration has been lost on one axis.

Jon