Re: [CAD_CAM_EDM_DRO] running brushless servos with emc

carlcnc wrote:

> I am the very lucky owner of a 3axis setup that has brushless servos.
> Draw back is that control system was via delta-tau cards.
> Amplifiers are copely 10v+- signals. I need help/advice on what I
> need to add so I can use EMC for control.

You can use a Servo-to-Go card (about $888) or my parallel port
axis control cards (about $500 right now, but digital I/O is not finished
yet.) See http://pico-systems.com/PPMC.html for more info.

>
> I have two of these machines and one is part way thru a conversion
> to steppers. Seems a waste to do this to the second one.
> The motor/encoder/amplifier/power supply connections are all intact
> omly my inexperience is keeping me from having a very cool servo
> 20x20x12 machine.

When you see how well it runs with servos, you may UN-convert the
first machine!

Either way, the setup is not much more complicated with the servos and
encoders than for steppers. What you do is connect the encoders to
the encoder input. Right away, you can see the position readout on the
EMC screen, with EMC in e-stop mode. you can adjust the scaling
factor to get the axis readout to have the correct polarity and precise
units (ie. a 1" move reads 1.000 inch on display).

Then, you connect the DAC output to the servo amps and enable them,
with the P (gain) parameter in the EMC .ini file set real low, and make
sure the machine is stable, but sluggish. (If the DAC polarity is
backwards, the machine will run away (slowly) rather than holding
position. In this case, you set the output scale to -1 in the ini file and
try again. if this works, you then turn the P gain up and adjust for
good response without overshoot.

I can advise on the tuning of the servo response.

Jon