Faro PCS (Part Coordinate System or Reference Frame) Issue

jr6300
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Faro PCS (Part Coordinate System or Reference Frame) Issue

Post by jr6300 » Thu Dec 06, 2018 9:34 am

We are experiencing an interesting issue when writing and rerunning a program on our Faro Platinum Arm running CMM Manager 3.7 SP2.

When a program is written the results are fine. If we rotate the base that the Faro is mounted about 90° and rerun the same program the results are also fine. When we rotate the base 180° the Actual Dimensions are reversed. By reversed I mean the results come in as negative rather than positive.

Since I cannot upload an excel workbook I have attached 4 snapshots of the study. The 1st picture shows the base setup and print. The next 3 show the results in Zero, 90° and 180° positions.

The Faro is not removed from the base. The base is simply rotated and the same program is reran. This is making no sense to me since the PCS or Part Reference Frame is recreated in each program run. Nothing is physically changed in the program nor the Faro.
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Re: Faro PCS (Part Coordinate System or Reference Frame) Issue

Post by jr6300 » Thu Dec 06, 2018 11:29 am

I didn't perform this study.

We will try homing the Faro after each move of the mounting base and I'll post the findings.

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Re: Faro PCS (Part Coordinate System or Reference Frame) Issue

Post by Murguel » Thu Dec 06, 2018 12:21 pm

Bearing in mind, the Faro Arm doesn't make any difference from where the measured point is coming from (it just takes the center of the probe), I believe, you have a faulty alignment.

Sometimes the alignment is faulty but still showing good results because the arm is in an "suitable" position. However. Changing the arms orientation just exposes your error, it doesn't cause it.

I am new with CMM Manager, so I cannot tell you what might be wrong. But I believe it could be a LINE that you measure for the alignment. If CMM Manager option "Determine Line Axis by Order of Points" is activated, CMM Manager would probably value the order of your measured points for your line different, depending on the Arm-Orientation.

You may try to change that setting - If you have a LINE in your ALIGNMENT.
But what I defintively would try, check the Logik behind your Alignment and validate whether it is water-proof.

Finally your measurement results are all more or less the same, but your Alignment goes horrible wrong as your Axis is twisted.

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Re: Faro PCS (Part Coordinate System or Reference Frame) Issue

Post by jr6300 » Thu Dec 06, 2018 2:24 pm

Same issue even after completely shutting down and re-homing the Faro between the Zero and 180°program runs.

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Re: Faro PCS (Part Coordinate System or Reference Frame) Issue

Post by jr6300 » Thu Dec 06, 2018 2:38 pm

Murguel wrote:
Thu Dec 06, 2018 12:21 pm
Bearing in mind, the Faro Arm doesn't make any difference from where the measured point is coming from (it just takes the center of the probe), I believe, you have a faulty alignment.

Sometimes the alignment is faulty but still showing good results because the arm is in an "suitable" position. However. Changing the arms orientation just exposes your error, it doesn't cause it.

I am new with CMM Manager, so I cannot tell you what might be wrong. But I believe it could be a LINE that you measure for the alignment. If CMM Manager option "Determine Line Axis by Order of Points" is activated, CMM Manager would probably value the order of your measured points for your line different, depending on the Arm-Orientation.

You may try to change that setting - If you have a LINE in your ALIGNMENT.
But what I defintively would try, check the Logik behind your Alignment and validate whether it is water-proof.

Finally your measurement results are all more or less the same, but your Alignment goes horrible wrong as your Axis is twisted.
We are running the exact same program so the alignment is the same each time, but the results are reversed.

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Re: Faro PCS (Part Coordinate System or Reference Frame) Issue

Post by Murguel » Fri Dec 07, 2018 4:25 am

jr6300 wrote:
Thu Dec 06, 2018 2:38 pm
We are running the exact same program so the alignment is the same each time, but the results are reversed.
I understood that. Absolutely clear to me.

My question was: Which alignment do you use? 3-2-1 ? RPS ? Can you post a screen shot?

Do you have a LINE Object in your alignment? Or do you align with 3 Planes or 3 Holes? It would be good to get a screenshot. I have an idea what your problem might be.... but I need to understand your measured Elements.

Sometimes your alignment seems to be logical, but when you have a deeper look into, you may recognize that it can be mis-interpreted.

Here is an Example. When you have such a part and use 3-2-1 Alignment and align the Y-Axis based on the measured Linie, then you could get a twisted alignment, based on how you measure the line. Therefore my Tip: Plesae check or change your alignment.

Again: When you 180° (or similar) roate your Arm, then the direction of the measured axis points to opposite Direction, what causes a rotation of your Reference Frame. CMM Manager is "special" regarding Line Measurements.
Alignment.png
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Last edited by Murguel on Fri Dec 07, 2018 3:14 pm, edited 1 time in total.

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Re: Faro PCS (Part Coordinate System or Reference Frame) Issue

Post by jr6300 » Fri Dec 07, 2018 11:14 am

We have found that if we use a Canned setup the results will not reverse if we rotate the Faro mount about 180°. If we do a level, align and set origin, not using a canned setup, that is when we see the reversals.

So that tells me there is something different going on in the canned setups, but that still doesn't make sense why it is reacting in this fashion...IMO.

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Re: Faro PCS (Part Coordinate System or Reference Frame) Issue

Post by Murguel » Mon Dec 10, 2018 3:37 am

I cannot help you if you do not respond to questions. I asked the same question 2 times but you did not respond.

Maybe the support could help you. You better send your program file to the Nikon Support.

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Re: Faro PCS (Part Coordinate System or Reference Frame) Issue

Post by jr6300 » Mon Dec 10, 2018 8:53 am

Murguel wrote:
Fri Dec 07, 2018 4:25 am
jr6300 wrote:
Thu Dec 06, 2018 2:38 pm
We are running the exact same program so the alignment is the same each time, but the results are reversed.
I understood that. Absolutely clear to me.

My question was: Which alignment do you use? 3-2-1 ? RPS ? Can you post a screen shot?

Do you have a LINE Object in your alignment? Or do you align with 3 Planes or 3 Holes? It would be good to get a screenshot. I have an idea what your problem might be.... but I need to understand your measured Elements.

Sometimes your alignment seems to be logical, but when you have a deeper look into, you may recognize that it can be mis-interpreted.

Here is an Example. When you have such a part and use 3-2-1 Alignment and align the Y-Axis based on the measured Linie, then you could get a twisted alignment, based on how you measure the line. Therefore my Tip: Plesae check or change your alignment.

Again: When you 180° (or similar) roate your Arm, then the direction of the measured axis points to opposite Direction, what causes a rotation of your Reference Frame. CMM Manager is "special" regarding Line Measurements.

Alignment.png
The alignment is between 2 circles or holes.

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Re: Faro PCS (Part Coordinate System or Reference Frame) Issue

Post by Murguel » Tue Dec 11, 2018 9:30 am

Hi, I do not want to make you wrong promises. I am not an expert for CMM Manager because I worked many years with PowerInspect, what is far away from CMMManager related to Process-Flow and Alignment.

If nobody else should have an idea, I can still try to help. I am a curious person and interested. If there should be an issue, then it's better I know it.

Coming back to your issue. Aligning with 2 circles and a plane should normally not a problem. And you should not have an issue with axis directions because you are not measuring a line. But from here I cannot tell you what's wrong. Better would be, you delete most of the items from your program and put a copy here. Maybe we can all have a look and somebody recognized your error. I have no issues to test your program with our machine - just to confirm, whether we have the same effect.

It's up to you.

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