Reconfigurable Inspection Machine
(RIM)
Overview
•
•
•
•
The RIM and the inspection methodology
What can the RIM measure and how?
Comparison of measurement results
Conclusion and future work
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College of engineering, University of Michigan
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Reconfigurable Inspection
Machine (RIM)
Engine cylinder head
Vision
system
Laser
probes
Slide system
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College of engineering, University of Michigan
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General Measurement Capabilities of
the RIM
• Dimensional:
Distance between edges, between surfaces or between holes
Dimensions of holes and inclination angles of chamfers
• Geometrical:
Flatness of surfaces
Parallelism between surfaces
• Surface Texture:
Porosity defects on a surface
Surface roughness (ongoing research)
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College of engineering, University of Michigan
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RIM and Conventional CMM
Measurements Differ. Why?
• Different measurements due to contact
probe radius.
• Different point densities.
• Different flatness calculation algorithms.
• Device dependant characteristics.
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College of engineering, University of Michigan
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Interpretation Is Required for
Contact Probe. Why?
x*j
o( x*j )
R
P
e*j
*
j
z( x )
Actual
surface
point
z*j
Interpreted
measurement
point
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College of engineering, University of Michigan
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The “Virtual Ball” Algorithm
x*j
xi
o( x*j ) 
max
x*j  R  xi  x*j  R
H ( x , x )
i
*
j
R
H ( xi , x )  R  ( xi  x )  zi
*
j
2
* 2
j
Interpreted height: o( x*j )  R
x*j  R  xi  x*j  R
Ball
contact
point
NFS Engineering Research Center for Reconfigurable Manufacturing Systems
College of engineering, University of Michigan
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Measurement example with
Virtual Ball interpretation
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College of engineering, University of Michigan
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Flatness Calculation by RIM
“Virtual ball” interpreted points
2 planes
Parallel to best fit plane
That confine the
Measured points
Flatness
LSQ fit plane to
Measured points
Laser measured points
Filter outliers outside 3 zone
NFS Engineering Research Center for Reconfigurable Manufacturing Systems
College of engineering, University of Michigan
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Width and Parallelism
Calculation by RIM
“Virtual ball” interpreted points
joint & cover faces
Point confining planes
parallel to datum
+
Parallelism
- Width
Best fit plane of cover face
parallel to datum
Daturm, LSQ fit plane to
joint face measured points
Laser measurements cover face
Laser measurements joint Filter
face outliers outside 3 zone
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College of engineering, University of Michigan
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Measurement Results
• Parts were measured by Inspec using a CMM.
• Results compared RIM measurements:
–
–
–
–
–
Distance between joint and cover face
Parallelism between joint and cover face
Flatness of joint and cover face
Hole diameter
Distance between holes centers
• Manual measurements serve as additional
reference
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College of engineering, University of Michigan
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Result Comparison
Manual
Inspection
Inspec
Part
RIM
RIM
Laser
measurements
reference
measurements
CMM
measurements
Comparison
Vision
measurements
Interpretation
using the
Simulated
contact probe
measurements
“Virtual ball”
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College of engineering, University of Michigan
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Inspec Measurements
• Measurements were obtained in two methods:
• Point on 3 lines (yellow)
• Point spread (yellow + blue)
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College of engineering, University of Michigan
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Manual Measurements
• Parts width was measured manually with 25µm
accuracy.
• Part width was measured in 8 points and
parallelism was deduced.
• Hole diameters were measured twice.

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College of engineering, University of Michigan

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Part Width
Inspec
(mm)
RIM
(mm)
Difference
(mm)
Part 1
119.550
119.531
0.019
Part 3
118.975
119.106
-0.131
Part 4
118.332
119.011
-0.679
Part 5
119.140
119.132
0.008
values for filtered data (outliers outside 3 zone removed after virtual ball interpretation)
Allowed Tolerance : 119 0.2
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College of engineering, University of Michigan
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Part Width - Detailed
Inspec
(mm)
RIM
mean
(mm)
RIM Plus
tolerance
(mm)
RIM Minus
tolerance
(mm)
Manual
(mm)
Part 1
119.550
119.531
0.060
-0.092
Part 3
118.975
119.106
0.038
-0.038
119.115
Part 4
118.332
119.011
0.630
-0.635
118.934
Part 5
119.140
119.132
0.407
-0.396
119.095
values for filtered data (outliers outside 3 zone removed after virtual ball interpretation)
Allowed Tolerance : 119 0.2
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College of engineering, University of Michigan
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Parallelism Between Joint
and Cover Faces
Inspec
(mm)
RIM
(mm)
Difference
(mm)
Manual
(mm)
Part 1
0.063
0.116
-0.053
Part 3
0.975
0.035
0.940
0.030
Part 4
0.306
1.229
-0.923
0.870
Part 5
0.653
0.758
-0.105
0.480
values for filtered data (outliers outside 3 zone removed after virtual ball interpretation)
Allowed Tolerance : 0.100
//
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College of engineering, University of Michigan
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Flatness of Joint Face
Inspec
(µm)
RIM
(µm)
Difference
(µm)
Part 1
22
35
-13
Part 3
37
41
-4
Part 4
65
37
28
Part 5
48
46
2
values for filtered data (outliers outside 3 zone removed after virtual ball interpretation)
Allowed Tolerance : 100 µm
NFS Engineering Research Center for Reconfigurable Manufacturing Systems
College of engineering, University of Michigan
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Flatness of Cover Face
Inspec
(µm)
RIM
(µm)
Difference
(µm)
Part 1
20
74
-54
Part 3
40
22
18
Part 4
27
44
-17
Part 5
22
22
0
values for filtered data (outliers outside 3 zone removed after virtual ball interpretation)
Allowed Tolerance : 100 µm
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College of engineering, University of Michigan
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Hole Diameter
Inspec
(mm)
RIM
(mm)
Difference
(mm)
Manual
(mm)
Part 1 - 1
16.032
16.128
-0.096
15.964
Part 4 - 1
16.103
15.966
0.137
16.027
Part 5 - 1
16.304
16.138
0.166
16.147
Part 1 - 2
16.022
16.036
-0.014
15.976
Part 4 - 2
16.031
16.043
-0.012
16.147
Part 5 - 2
16.248
16.193
0.055
16.147
2
Allowed Tolerance : 16.2  0.2 mm
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College of engineering, University of Michigan
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1
Distance Between Holes
Inspec
(mm)
RIM
(mm)
Difference
(mm)
Part 1
305.991
305.768
0.223
Part 4
305.981
305.752
0.229
Part 5
305.984
305.803
0.181
Allowed Tolerance : 306  0.1 mm
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College of engineering, University of Michigan
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Different number of probes
RIM
3 scan lines
(µm)
RIM
2 scan lines
(µm)
Difference
(µm)
Part 1
35
31
4
Part 3
41
39
-2
Part 4
37
31
6
Part 5
46
46
0
values for filtered data (outliers outside 3 zone removed after virtual ball interpretation)
Maximum deviation : 6 µm
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College of engineering, University of Michigan
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Conclusions
• Overall, laser measurements are in the same range
• The RIM may be used for process monitoring with a backup CMM.
• Differences may result from:
–
–
–
–
–
Different measurement methods
Different measurement environment
Different algorithms
Measurement uncertainties (imperfect calibration)
Human error (further testing required)
• Different number of probes per face (2 or 3) had negligible effect on
the results
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College of engineering, University of Michigan
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Future Work
• Further result analysis.
• Repeating CMM measurements for
additional reference.
• Testing for repeatability and reliability.
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College of engineering, University of Michigan
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Acknowledgements
• This research was supported in part by the NSF
Engineering Research Center for
Reconfigurable Machining Systems under the
grant EEC95-92125.
• The RIM project team.
• Dr. G. Sirat from Optimet.
• Cummins metrology department.
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College of engineering, University of Michigan
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RIM Team
Project Team:
ERC:
Dr. Reuven Katz
Dr. Jacob Barhak
Students: Anuj Gupta
Glenny Tjahjadi
ERC
ERC
EECS
EECS
Dr. Steve Segall
Avinash Kalyanaraman
Yoou-Soon Kim
ERC
EECS
ME
Industrial partners:
Ashish Kachru
Robert J. Hogarth
Tim Lock
Cummins
GM
Vision Solutions, Inc.
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College of engineering, University of Michigan
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