SpatialAnalyzer

Unified Spatial Metrology Network (USMN)

The feature Unified Spatial Metrology Network (USMN) in SpatialAnalyzer® (SA) provides answers to your measurement uncertainty issues in an easy to use and understand environment. The USMN is GUM compliant and meets ISO standard requirements. Many large-scale measurement processes require more than a single measurement instrument. Examples include commercial airplane production and shipbuilding. These applications necessitate either a combination of various measurement devices or the relocation of a single instrument throughout the measurement volume in order to acquire the necessary data.

Users often combine measurement systems by tying individual measurement systems together based on common reference points, and then assume they are still working within the instruments published uncertainty. Alternatively, many users apply heuristics to determine the uncertainty as they progress along a chain of measurements. These methods provide very poor approximations of uncertainty in all but the most simplistic cases. Even in cases where only a single placement of an instrument is used, its measurements are typically tied in to a reference coordinate system. The uncertainty from this tie-in process is often ignored.

The ISO (International Organization for Standardization) standards focusing on Global Product Specification require that part measurements be described by two numbers. The first is the result of the measurement and the second is the stated uncertainty. This uncertainty statement represents the estimated variability in the result. This specification mandates uncertainty statements in order to provide traceability for measurement results. In addition, it is recommended that measurement systems provide uncertainty statements in order to be considered accredited systems (Forbes and Harris, 2000). The National Institute of Standards and Technology states that a measurement result is complete only when accompanied by a quantitative statement of its uncertainty. USMN makes it a reality for real-world measurement applications.

Common Questions

• What is the uncertainty of my instruments in the real-world?
• What is the effect of uncertainty propagation on the quality of my measurements?
• How can I make optimal use of my measurements to minimize uncertainty?
• Ok, its nice to know the uncertainty of a point, but Im fitting a sphere. What is the uncertainty of my fit?
• What about my hidden point bar?

Answers

• Combine measurement systems
• Characterize instrument uncertainty
• Verify instrument performance
• Determine uncertainty fields
• Take advantage of the relative uncertainty of the measurement components.
• Geometric fitting uncertainty (sphere, line, plane, cylinder, etc)
• Characterize Instrument Uncertainty
• Measure fixed points from multiple stations
• Solve network
• Extract component uncertainties from residuals. (Type A evaluation)
• Test under real-world conditions!
• Input uncertainties into SA to determine effect on your measurement process

Coordinate Uncertainty Fields Measurement System Combination

• Uncertainty Propagation
• Add Another Instrument to the Measurement Chain
• Combined Uncertainty!
• Single Measurement to Close the Loop:
  • Drastic Uncertainty Reduction

Relative Uncertainty Optimization

• Weighted solution
• Each measurements individual components weighted independently.
• Essential for mixed instrumentation.
• Better, more realistic fit on your data.
• Instrument Combinations

Analysis: Hidden Point Bar Uncertainty

• Uncertainty Fields Interact
• End-Point is extrapolated and so is the uncertainty.

More Instrument Combinations

• Do you really know the effects of your measurement chain? USMN can help.

Geometry Fitting Uncertainty

• What is the uncertainty of the tooling ball center in the part frame?

Does Coverage Matter?

• Geometry Fitting Uncertainty
• What is the uncertainty of a measured cylinder?
• Does coverage matter?
• Complex, Mixed-Instrument Networks
• How does your uncertainty propagate?

Simulation & Measurement Planning

• Uncertainty Reduction Results:
• User Interface
• Advanced Options
• Select weighting scheme simulate a traditional best-fit
• Adjust instrument uncertainty values input values from your characterization.

Summary

• Characterize your instruments performance in your world.
• Advanced uncertainty analysis right to the shop-floor.
• Clearly shows the effects of measurement uncertainty on analysis functions.
• Uncertainty fields help to put all those unused pixels on your screen to good use!

Questions? Contact us at support@kinematics.com.