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#10846 - 05/09/11 03:37 PM Dual Motors on Single Axis
brplatz Offline
Junior Member

Registered: 05/09/11
Posts: 10
Loc: Albuquerque, NM
I am not sure how to set up a system I am working on.

Essentiall I am revamping a large old stepper motor 3 axis mill used for sheets of plywood.

I am using a DMC-1886 and some Parker BE34 Servomotors. I have 2 of them on one axis that runs a gantry over the table and are connected directly to gears and racks on each side.

Should I be using electronic gearing to control one and then the other as a slave?

Also how would i tune it?

Thanks,
Brian


Edited by brplatz (05/09/11 03:38 PM)

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#10847 - 05/09/11 03:39 PM Re: Dual Motors on Single Axis [Re: brplatz]
AndyH Offline

Member

Registered: 12/20/05
Posts: 583
Loc: Rocklin, CA
Yes, you use two separate axes on the Galil, then gear the axes through electronic gearing. You want to gear off of commanded position instead of actual position. See the GA command in the command reference for details.
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Andy Herum
Senior Applications Engineer
Galil Motion Control

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#10848 - 05/09/11 03:58 PM Re: Dual Motors on Single Axis [Re: AndyH]
brplatz Offline
Junior Member

Registered: 05/09/11
Posts: 10
Loc: Albuquerque, NM
Ah, perfect I thought it would be something like that.

Now how do I go about tuning, one then the other? Because when there running together each will be sharing the load, so it seems like I would have to tune them at the same time?

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#10849 - 05/10/11 08:41 AM Re: Dual Motors on Single Axis [Re: brplatz]
AndyH Offline

Member

Registered: 12/20/05
Posts: 583
Loc: Rocklin, CA
Get them tuned individually, but then back off the parameters by ~20%. The load should be stable at this point and you can then tune when the axes are running together.
_________________________
Andy Herum
Senior Applications Engineer
Galil Motion Control

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#10850 - 05/10/11 09:10 AM Re: Dual Motors on Single Axis [Re: AndyH]
brplatz Offline
Junior Member

Registered: 05/09/11
Posts: 10
Loc: Albuquerque, NM
Thanks Andy,

I really appreciate the fast replies, I'll give it a go today once I get everything all wired up.

Also on the programming aspect

GA, CX will set commanded position of X for the master of Y?
GR ,-1 will have it at the same speed as X but in the reverse direction correct?

Brian


Edited by brplatz (05/10/11 09:29 AM)

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#10851 - 05/11/11 08:17 AM Re: Dual Motors on Single Axis [Re: brplatz]
brplatz Offline
Junior Member

Registered: 05/09/11
Posts: 10
Loc: Albuquerque, NM
How should the GM be used, in the command reference it says
GM ,1 ;Sets gantry mode for X as Master and Y as slave.

Do I still need a GA ,CX Command?

The gantry I am working on is quite heavy and I would prefer to do all this right the first time.

Brian

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#10852 - 05/11/11 08:21 AM Re: Dual Motors on Single Axis [Re: brplatz]
AndyH Offline

Member

Registered: 12/20/05
Posts: 583
Loc: Rocklin, CA
GM,1 is correct for Y axis as the slave. You still need the GA command, and the syntax for that is correct as well.
_________________________
Andy Herum
Senior Applications Engineer
Galil Motion Control

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#10853 - 05/11/11 09:41 AM Re: Dual Motors on Single Axis [Re: AndyH]
brplatz Offline
Junior Member

Registered: 05/09/11
Posts: 10
Loc: Albuquerque, NM
Is it possible to use GR to to reverse the direction of the Y axis? Or does the GM make it so that Y is already "geared" to follow X?

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#10854 - 05/11/11 09:55 AM Re: Dual Motors on Single Axis [Re: brplatz]
AndyH Offline

Member

Registered: 12/20/05
Posts: 583
Loc: Rocklin, CA
The gear ratio can be updated at any time during gearing.
_________________________
Andy Herum
Senior Applications Engineer
Galil Motion Control

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#10876 - 05/16/11 12:11 PM Re: Dual Motors on Single Axis [Re: AndyH]
brplatz Offline
Junior Member

Registered: 05/09/11
Posts: 10
Loc: Albuquerque, NM
Andy

I have another issue. I can servo my motors currently and it seems i can successfully change the PID values also. However when I attempt to tune using the WSDK I get no movement.

When I attached it to my gantry setup, the system vibrates extremely violently at a nearly deafening tone.

Here is a photo of my tune attempts.

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