Re: Re: Stepper program w/Encoders?

Alan,
If you are putting a uP in there loop, why not make it figure out all
the backlash parms... including dead time!
I've had the idea for a while, and was going to expand it with a lookup
table to generate thread compensation, that way it would
move the true distance and lead screws become anything you want them to
be... It all depends on the feedback resolution...
I'm an electronics kind of person also...
Which uP are you using ?

Hans Wedemeyer

beer@... wrote:

> On 2 Dec, CAD_CAM_EDM_DRO@onelist.com wrote:
> > Message: 6
> > Date: Wed, 1 Dec 1999 10:58:52 -0700
> > From: "Tim Goldstein" <timg@...>
> > Subject: Stepper program w/Encoders?
> >
> > I seem to remember someone mentioning a stepper controller program
> that
> > would support encoder feedback for a closed loop, but don't remember
> what
> > the program was. Does anyone remember which program supports this
> > functionality and the URL for it?
> >
> > Thanks,
> > Tim
>
>
> Tim;
>
> I'm attempting to do this in hardware.
>
> This counter that I'm sending to you ( this weekend, all going well )
> is actually the first rev of a project to close the loop in hardware.
>
> Being too cheap to spend the money on ballscrews and being an
> electronics kinda guy and NOT a machinist, I've trying to produce an
> electronic solution.
>
> Here's what my gizmo will do.
>
> It accepts input from a positioning device. Currently I'm struggling
> with getting zero-lash rotary devices. ( I'm about to have some 1000
> line linear films made up and give up on the rotary idea ) The
> device
> happens to display the current position; that is, the gizmo is a DRO.
>
> However, it also accepts step and direction inputs AND OUTPUTS step
> and
> direction signals. It has one other output I call "pause".
>
> The gizmo normally acts as a conventional DRO, while at the same time
> looks for step signals. When it sees a step input, it outputs a step
> AND THEN WATCHES THE DRO TO SEE IF SOMETHING ACTUALLY HAPPENED. If no
> movement occurred ( i.e., backlash ), PAUSE is asserted, stopping the
> CNC software and additional step commands are issued by the gizmo
> until
> movement DOES occur. Pause is then released and normal CNC operation
> continues.
>
> ( CNCPro now accepts this "pause" input, although I haven't actually
> purchased a copy yet, as I'm not quite ready to use it. I certainly
> will once all IS ready to go, though )
>
> This device is somewhere between breadboard and installation. As I
> said, I'm still twiddling with the DRO, still twiddling with my
> stepper
> controller ( adding microstepping to the current half/full step ) and
> still finishing the new shop that the machines live in ( if a 7x11
> room
> can be called a shop .. cave is a bit more appropriate ).
>
> It's taking a while longer than planned, as I have a small electronics
> design business as well as my normal 9-5 and people just won't leave
> me
> alone ! Normally, this is good cuz the business pays for my toys, but
> now I want some time to PLAY with my toys, darnit !
>
> Also, there is likely to be some finetuning of the software in the
> microcontroller, specifically to do with timing. ( How long should we
> wait after a step before deciding that more steps are required and how
> quickly should we issue those steps and at what rate. Smoothness as
> it affects surface finish is less of an issue here, thankfully, as the
> cutter isn't actually moving as a result of these extra steps. )
>
> Anyway, your counter-tach is soon on the way.
>
> Alan
>
> --
>
> Alan Rothenbush | The Spartans do not ask the number of
> the
> Academic Computing Services | enemy, only where they are.
> Simon Fraser University |
> Burnaby, B.C., Canada | Agix of
> Sparta
>
>
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