Re: Manual Control

I've done this. I have the handwheels turn a rotary encoder. The
encoders generate quadrature pulses in the usual way and I count those
pulses on a counter. In my software, I then formulate a servo command
position for that axis based on the number of counts revceived per
unit time and the direction of the handwheel turn.

The handwheel encoders are completely seperate form the axis encoders
that are used for position feedback during automatic control. When
you turn the handwheel, you don't directly affect the ballscrew. Only
the motor makes the ballscrew turn.

I use this on a machine that has linear encoders for axis position
feedback. This has a couple of desirable effects. The handwheel is
directly attached to the rotary encoder, so there is almost no
backlash there, as long as the handwheel setscrew isn't loose or
something. Since the axis encoders are linear, no counts occur when
the ballscrew is turning to take up baklash, so counts on the linear
encoder can be safely assumed to represent actual motion. This makes
for extremely precise manual control. Also, I can change the distance
the axis moves per handwheel revolution entirely in software, by
changing a "gain" setting.

Commercial controls do this. For instance on most of the Fanuc lathe
controls I've used (16T?) they have a wheel called the "mpg" for
Manual Pulse Generator. You select jog, select which axis to jog,
then spin the mpg to make the axis actually move.

Mike



--- In CAD_CAM_EDM_DRO@yahoogroups.com, "roboticscnc" <gsm42@o...>
wrote:

>
>
> Hi Group,
> Has anyone set up dials with encoders to manually control a lathe

with

> the servos, if so, how do these encoders intergrate with the rest of
> the system ? I'm not worried about backlash as the lathe has a DRO.
> Thanks,
> Glen