Assign the Average Deviation and Standard Deviation of a Profile

Hi Y'all.

I have a simple question with a long-winded lead up, so please bear with me.

I have a customer that would like us to start reporting the Average Deviation and Standard Deviation of profile measurements. They even want to apply tolerances to these metrics. So, I'm looking for a way to display these on the report with a tolerance applied. That way our CMM operators can make a quick pass/fail judgment on each part.

I see that PC-DMIS has the option to display these metrics in a DIMINFO box, but I don't see a way to make them appear directly on the report. Even so, what I would really like to do is assign those values to some variables so I can go the route of putting them in generic features and reporting them with tolerances applied.

For example. Here is a Legacy Profile Dimension from the Edit Window:

And how it appears on the report:

From the DimInfo Box Dialog window I have access to the metrics I want.

And I can see from the Graphics Display Window that the values are being calculated:

I found that I can get the Standard Deviation using the GetText command:

However, I just can't seem to find a way to get the Mean value.

Does anyone know how I can assign the Mean value to a variable? Or possibly an easier way to get the Standard Deviation value?
Or can you think of any other routs I may take to report these metrics with tolerances applied?

Parents

Cris_C over 1 year ago

You said assignment ?

DISPLAYPRECISION/6 (or 7 in inches)
ASSIGN/T_VALUE=DOT(DSCN01.HIT[1..DSCN01.NUMHITS].XYZ-DSCN01.HIT[1..DSCN01.NUMHITS].TXYZ,DSCN01.HIT[1..DSCN01.NUMHITS].TIJK)
ASSIGN/MEAN=AVERAGE(T_VALUE)
ASSIGN/STD_DEV=SQRT(SUM(T_VALUE^2-MEAN^2)/(DSCN01.NUMHITS-1))

If there's no AVERAGE in your version, just

ASSIGN/AVERAGE=SUM(T_VALUE)/DSCN01.NUMHITS

Thank you JEFMAN. That does the trick.
I was hoping to be able to just grab the value that PC-DMIS can calculate itself, but that doesn't seem to be an option. At least with your method I know for sure that the math is right

.

For what it's worth, your code returned the same exact value as I saw in the Diminfo box. It's nice to be able to double check PC-DMIS's math. After you post a while back that questioned the math behind outlier removal, I was a little concerned if the software would calculate the standard deviation the way I would expect. I'm happy to see that in this case it does.

I am trying to modify your code to make something that I can easily cut and paste after each profile feature. I am using the GETTEXT and GETCOMMAND functions to automatically get the referenced feature from the profile feature that precedes it. I'm able to assign a pointer to that feature, but I'm having trouble getting data about individual hits from that pointer. Here is some code:

DIM DIM44_1= PROFILE OF SURFACE OF SET DSCN01    FORMANDLOCATION  UNITS=IN ,$
GRAPH=OFF  TEXT=OFF  MULT=100.00  ARROWDENSITY=100  OUTPUT=BOTH
AX    NOMINAL       +TOL       -TOL       MEAS        MAX        MIN        DEV     OUTTOL
M      0.00000    0.00500    0.00500    0.00693    0.00377   -0.00316    0.00693    0.00000 #-|-#
            ASSIGN/PRO_FEAT={GETTEXT("REFERENCE ID",0,GETCOMMAND(1105,"UP",1))}     <--------------Returns a pointer to "DSCN01".  Good!
            ASSIGN/T_VALUE=DOT(PRO_FEAT.HIT[1..PRO_FEAT.NUMHITS].XYZ-PRO_FEAT.HIT[1..PRO_FEAT.NUMHITS].TXYZ,PRO_FEAT.HIT[1..PRO_FEAT.NUMHITS].TIJK)   <----------Returns 0? No data
            ASSIGN/V1=PRO_FEAT.HIT[1].XYZ   <----------Tried to get XYZ of just one point. Also returns 0?  
            ASSIGN/V1=PRO_FEAT.HIT[1].X     <----------Tried to get X of just one point. Also returns 0?  
            ASSIGN/V1=PRO_FEAT.XYZ          <----------Tried to get XYZ of centroid of scan, Returns "<8.4955, 21.8442, 1.6928>".  So at least that works.  
            ASSIGN/V1=PRO_FEAT.NUMHITS      <----------Tried to get number of hits, Returns "5904".  That is correct too.

Any ideas what I am doing wrong?

Reply

Cris_C over 1 year ago

You said assignment ?

DISPLAYPRECISION/6 (or 7 in inches)
ASSIGN/T_VALUE=DOT(DSCN01.HIT[1..DSCN01.NUMHITS].XYZ-DSCN01.HIT[1..DSCN01.NUMHITS].TXYZ,DSCN01.HIT[1..DSCN01.NUMHITS].TIJK)
ASSIGN/MEAN=AVERAGE(T_VALUE)
ASSIGN/STD_DEV=SQRT(SUM(T_VALUE^2-MEAN^2)/(DSCN01.NUMHITS-1))

If there's no AVERAGE in your version, just

ASSIGN/AVERAGE=SUM(T_VALUE)/DSCN01.NUMHITS

DIM DIM44_1= PROFILE OF SURFACE OF SET DSCN01    FORMANDLOCATION  UNITS=IN ,$
GRAPH=OFF  TEXT=OFF  MULT=100.00  ARROWDENSITY=100  OUTPUT=BOTH
AX    NOMINAL       +TOL       -TOL       MEAS        MAX        MIN        DEV     OUTTOL
M      0.00000    0.00500    0.00500    0.00693    0.00377   -0.00316    0.00693    0.00000 #-|-#
            ASSIGN/PRO_FEAT={GETTEXT("REFERENCE ID",0,GETCOMMAND(1105,"UP",1))}     <--------------Returns a pointer to "DSCN01".  Good!
            ASSIGN/T_VALUE=DOT(PRO_FEAT.HIT[1..PRO_FEAT.NUMHITS].XYZ-PRO_FEAT.HIT[1..PRO_FEAT.NUMHITS].TXYZ,PRO_FEAT.HIT[1..PRO_FEAT.NUMHITS].TIJK)   <----------Returns 0? No data
            ASSIGN/V1=PRO_FEAT.HIT[1].XYZ   <----------Tried to get XYZ of just one point. Also returns 0?  
            ASSIGN/V1=PRO_FEAT.HIT[1].X     <----------Tried to get X of just one point. Also returns 0?  
            ASSIGN/V1=PRO_FEAT.XYZ          <----------Tried to get XYZ of centroid of scan, Returns "<8.4955, 21.8442, 1.6928>".  So at least that works.  
            ASSIGN/V1=PRO_FEAT.NUMHITS      <----------Tried to get number of hits, Returns "5904".  That is correct too.

Any ideas what I am doing wrong?

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