FCS_Chris

Recommended Configuration of Axes & Coordinates - AB Studio 5000 Motion Control

8 posts in this topic

Hi all,

I would greatly appreciate any recommendations for appropriate configuration of axes and coordinates to enable control of the following 2D plotting device.

There's two physical axes:

  1. A rotary axis sets angular location of an arm.
  2. On the arm is a linear actuator that sets the length/extension of the arm. At the end of the arm is a pen.

What we would like to do is specify a pattern to be drawn in cartesian X, Y coordinates and for the PLC to do the necessary transforms and move the physical axes.

According to AB Studio 5000 documentation we:

  1. Setup physical axes - OK
  2. Create coordinate system - Ahhgh... our geometry is not supported!

Any recommendations on how to configuration the axes and coordinates for this machine?

Thank you,
Chris.

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Your description of the system is top-view.  How about the hardware.  Are your axes VFD-driven or servo?  Which servo controllers are you using?  Which PLC platform are you using?

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Hi kaiser_will,

Thanks for your message! Yes, this is a high level view as we're currently in  the planning phase and trying to determine appropriate hardware/software configuration.  More details below:

Quote

How about the hardware.  Are your axes VFD-driven or servo?

 Ideally VFD as very high precision is not required, but servos are an option.

Quote

Which servo controllers are you using?

We can specify as required

Quote

Which PLC platform are you using?

Ideally an Allen Bradley PLC however, if this can't do what's required, we're open to other options.

Cheers,
Chris.

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The specification is still wide open, then.  Where does "our geometry is not supported come from"?  

If the goal is to design a 2D plotting device, I would say high precision is required => servos.  Before you pick the servo controller, one must pick the servo motor that will need the motion requirements (mass to move, maximum speed required, travel distance).  The servo motor family will dictate the servo controller.

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Hi kaiser_will,

Thanks for following up. "our geometry is not supported" is from Rockwell's Studio 5000. When configuring a coordinates system, the geometry of the machine needs to be selected however, there's not an option for our required geometry.

What we're trying to determine is if we can build a solutionu usingAllen Bradley hardware/software.

The mechanical side is not an issue.

Cheers,

Chris.

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Rockwell/Allen-Bradley has a development software package, Motion Analyzer, that is well suited for this application.  With the software, one can model the mechanics of an application and determine if the servo motor and controller are sized properly, if the VFD can move a load within a time period.  http://ab.rockwellautomation.com/Motion-Control/Motion-Analyzer-Software

With A-B systems design, the critical components are servo motor/controller sizing (and if a gearbox is needed) & VFD motor/controller sizing (and if a gearbox is needed), as well as if the PLC controller can handle the motion tasks.

One can download for free, trial run period is 30 days without license.  http://www.motion-analyzer.com/download.action

Motion Analyzer is a software package developed by Electrical Engineers as a tool really for Mechanical Engineers.  So it ends up being overly complicated and cumbersome until you figure it out.  I have a simple Work Instruction, developed for our Mechanical Engineers to make the software application productive for them.  

Work Instruction - Allen-Bradley Motion Analyzer Software.doc

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If you're keen on using ControlLogix and your geometry isn't negotiable, then I think your only option is to use position cams.

This would involve dividing each planned move's trajectory into arbitrarily short segments and then converting the cartesian co-ordinates of each segment to polar co-ordinates. Put the angles and lengths into two separate cam tables and slave them to a virtual master axis. Then, a simple move of the virtual master will drive your two axes in the desired way. Smoothness will be determined by segment length.

 

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Hi Gents,

kaiser_will: Thanks again for following up and for your notes on Motion Analyser.

Gerry: Thanks for your suggestion. I was thinking of something along these lines but am concerned the logic could get pretty messy, especially as we would like to rotate or size the patterns to be drawn on the fly. I did find some sample code that could probably be modified and enhanced to do what we need and avoids setting up a coordinates system, again a bit messy though.

http://search.rockwellautomation.com/search?client=samplecode&oe=UTF-8&ie=UTF-8&output=xml_no_dtd&proxystylesheet=samplecode&site=sample_code&getfields=*&lang=en&hl=en&sort=date:D:L:d1&wc=200&wc_mc=1&ud=1&filter=0&q=Managing%20a%20Crank%20Geometry%20(Rev1)

Hopefully there's a neater solution out there?

Cheers,
Chris.

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