A Comparison of Touch & Optical CMM Probes

for the International STEP-NC Demonstration

(Renton, Wa. 2009)

Eric TingleWestern Regional Sales Manager / Mitutoyo America Corporation

Scott HarsilaMechanical Engineer / Micro Encoder, Inc.

Larry MaggianoCTL Senior Systems Analyst / Mitutoyo America Corporation

15 May 2009

Copyright Mitutoyo America Corp. 2009

Measurement Scenario

Copyright Mitutoyo America Corp. 2008

• AP238 v1 enables Measurement in– Touch Trigger Probe equipped MCs and CMMs to

1. Establish Coordinate Systems (6 DOF)2. Measure Features for Datum Reference Frames3. Measure vectored surface points

1. Construct multi-point Features2. Tolerance to GD&T standards

• What may be required in AP238 v? to– Enable 3D Optical Sensing for tasks 1 to 4 above?

Native CAD Model(Courtesy Boeing Corp.)

Measurement Point(s)

defined as CAD Entities

CMM with Touch Probe

CMM Touch Probe Results

CMM Touch Probe Results

AP238 Touch Probe Considerations

• Touch Probe points for Datum Features?– Define touch points explicitly?

• Task uncertainty to tolerance ratio?• Point “tunneling” accuracy?

– Maximum limit?• Min/max stylus tip diameter?

– Appropriate for surface curvature & clearance?– Contact averaging effect?

CMM with Optical Probe

CMM Optical Probe Results

CMM Optical Probe Results

AP238 Optical Probe Considerations

• Use Optical Probe points for Datum Features?– Or use point set from touch probe measurement?

• Task uncertainty to tolerance ratio?• Min/max point density per Feature?• Parameters for outlier removal (filtering)?• Parameter for trimming, as an offset from

Feature boundaries, for ‘over scanned’ points?

AP238 Scenario Results

• Defined touch probe points are extractable

• Optical probes are applicable

• Probe type (optical, scanning or touch trigger) defined for Working Steps

• Data from different sensor types is comparable

Copyright Mitutoyo America Corp. 2008