PR 255659 Measured angle has a different sign as in previous versions

huangyhg

Measured angle has a different sign as in previous versions

<< Frank Herr  --  06/26/08  20:19:01>>
In the attached part program the customer get a different sign (-) for the dimension 5013_1, 5013_2 and 5064_2. This dimensuions are using a plane and the 2D angle against the coordinate system axis. The customer has used before the Version 4.2 MR2 RC (Jan/27/2008). With that version they got a positiv measured value for this dimension. Also in Version 3.5

Steps to reproduce:
See attached pp.
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<< Changes made by Frank Herr -- 12/05/08  17:40:21>>
Status:  RESOLVED to CLOSED
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<< Changes made by Paola Pallo -- 07/18/08  09:59:31>>
Action:  Paola Pallo to Frank Herr, Status:  OPEN to RESOLVED
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<< Paola Pallo  --  07/15/08  17:34:48>>
The results you get now are correct, and coherent to the current design.
As you know to resolve the ambiguities causing many problems in the old versions,  we agree to change  the 2D angle math in v42MR2 and up (and when you load an old PRG containing angles you are informed that the math is changed with a message).
Now PC-DMIS applies the basic geometrical rules of the angles using the information available from the dimension itself , that is  the input features' type, their order inside the dimension and the current workplane .
Using above info, you will have the 2D_angle result according to the following conventional rules :
1) the angle is considered positive when it is measured counterclockwise ( the input feature's  order is counterclockwise) , otherwise it is considered negative.
2) the angle between two lines ( or reducible to line feature as cone, cylinder, slot, ellipse) is calculated using the feature's vector (taking in consideration also its sign)
3) the angle between two planes is defined as the angle between the planes' normal vector
4) a circle is considered as a plane feature
5) the angle between a plane and a line is calculated using a 'laying vector' that depends on the plane vector and  the current workplane   
Considering the case of  dimension 5013_1 , the result you get is negative exactly because the rule 1 ( the angle is calculated from the laying vector on the plane  <-0.03,0.99,0> and  <0,1,0>, which is clockwise, so negative angle) :
DIM 5013_1= 2D ANGLE FROM PLANE 5013 TO   YAXIS ,$
GRAPH=OFF  TEXT=OFF  MULT=10.00  OUTPUT=BOTH
AX       MEAS    NOMINAL        DEV       +TOL       -TOL     OUTTOL
A      -1.084      1.110     -2.194  
Inverting the features' order, you get a positive result ( see above a brief example)
LIN_YPLUS  =GENERIC/LINE,DEPENDENT,CARTESIAN,$
            NOM/XYZ,<0,0,0>,$
            MEAS/XYZ,<0,0,0>,$
            NOM/IJK,<0,1,0>,$
            MEAS/IJK,<0,1,0>,$
            DISTANCE/0,0
DIM WINKEL28= 2D ANGLE FROM LINE LIN_YPLUS TO PLANE 5013 ,$
GRAPH=OFF  TEXT=OFF  MULT=10.00  OUTPUT=BOTH
AX       MEAS    NOMINAL        DEV       +TOL       -TOL     OUTTOL
A       1.084      1.110     -0.026      0.300      0.300      0.000 #-
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<< Paola Pallo  --  07/01/08  17:40:44>>
Downloading the attachments to have a look
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<< Changes made by Tim Wernicke -- 06/26/08  13:23:36>>
Action:  Don Turcotte to Paola Pallo, Assigned:  Don Turcotte to Paola Pallo, Priority:  to High
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