Large Jig Verification

Report
LVMC 06
month 200X
Geraint W Jones
Engineering Group Leader Metrology
Airbus UK
Large Jig Verification
Project
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© AIRBUS UK LTD. All rights reserved. Confidential and proprietary document.
Background
Airbus Wing Size Comparison
July 2006
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Slide 3.5
Page 2
Stage 01 Jig
• The main geometrical features to be controlled during the periodic jig verification process are
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hinge lines for all the movables I.e. Spoilers and ailerons.
• On an A380 periodical verification of the assembly tooling approximately 150 points are measured
today
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Recertification
JIG PERIODIC RECERTIFICATION PROCESS
Prepare tool
Measure tool
Features
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In spec?
JIG HEALTH CHECK
No
Rework
Yes
Return tool to
production
End
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Project
PROJECT AIMS
The project aims to understand and improve the process capability of the Jig Health
Measurement process of a candidate Wing Assembly jig.
BENEFITS
Perceived benefits of the project include:
• Less rework due to measurement variation
• Improved accuracy and repeatability of the measurement process
• Improved product performance
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• Data base of capability for future design of wings and tooling
KEY FACTORS AFFECTING MEASUREMENT PERFORMANCE
• The measurement instrument
• The environment
• The measured features
• The measured object
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Instruments and Software
Measurement System & Software
Axyz Software
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Spatial Analyzer
Laser Tracker
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Φ=Horizontal angle
θ=Vertical angle
r=Distance
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Health Check Process
Existing Health Check
Measurement Process
Measure ERS points
Measurement
Measure jig geometry
points (OTP)
Execute the bundle
adjustment
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Generate hidden points
Data processing
Least squares best fit and
scale to nominal jig OTP’s
OTP point qualification
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Final report
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Measurement Phase
ERS- Enhanced Reference System
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• Network of points permanently attached to the tool
• Attached in positions on substantial structure where they can be seen from convenient
positions of the measurement system
• Can be used to orient the network of instruments and/or allow local positioning with respect
to some defined coordinate system
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Measurement phase
Typical Optical Tooling Points (OTP)
TYPICAL TRACK
FLAG VIEW
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VIEW A
VIEW A
B
A
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Measurement phase
Instrument Positions and Measurements
Position0
Position1
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Position2
Measured OTP’s
ERS points
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Data processing
Bundle Adjustment
• An algorithm which consists of an
optimisation routine.
• The transformation of each instrument is
determined which minimises the observational
errors of the system
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Minimized Pointing Error
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Data processing
Generate hidden points
Calculated Hidden Point
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Required OTP
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Data processing
Best fit and Scale to nominal Jig OTP’s
Trackers bundled, not best-fit
Jig Nom OTP’s
Unused Jig Nom OTP’s
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Measured OTP’s
Trackers bundled and best-fit
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Data processing
Best-Fit and scale to nominal jig OTP’s
• Least squares routine that minimises the sum of the squares
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•Scale: account for temperature effects on jig
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Final report
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OTP Qualification = Jig Health Check
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What can be done better?
Improvement opportunities
• Scale Factor not included
Apply
scale to the instruments
during network adjustment, not
points in the best-fit
• Assess Measurement Uncertainty
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“error
footprint” not applied
Least squares treats all points with
equal weight
Laser Tracker “error footprint”
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What can be done better?
Improvement opportunities
• The effect on measurement performance due to laser tracker instrument placement and ERS
proximity is unknown.
• If we knew these effects we could optimise and standardise the measurement procedure
• If we could express the measurement process capability it could result in:- Better informed decisions regarding rework
- Better designs for future tools
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- More appropriate specifications for setting and periodic checks
- Save time and money!!
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What can be done better?
Additional evidence to back up case for improvement
Evidence of ERS and subsequent OTP point variation upon recertification
• Excessive rework on seemingly stable tooling monuments
• ERS best fit results degradation
• No standard method for valuation of ERS involving how many instruments required,
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best practice for instrument placement and minimum points required for tie-in
• Use of DVT (hidden point) tooling can have detrimental effect on measurement performance,
need a case to back this up
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Measurement Uncertainty - U
D
• A parameter that is associated with the result of a measurement, that
characterises the dispersion of values that could reasonably be attributed
to the measurand (VIM 1993, 3.9)
• An uncertainty is not an error, which is defined as the difference between the result of a
measurement and the true value
• If a measurement error is known, a correction can be applied to achieve a more accurate
result. The remaining uncertainty (from that component) is the uncertainty in the correction
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Arriving at a measurement uncertainty for a typically Large Scale measurement process such
as this Airbus example involving multiple instrument locations was hitherto very difficult and
Impractical.This is now possible!
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Measurement uncertainty
How can we understand the effects of instrument uncertainty, placement and the measurement
procedure for Large Jig Verification?
• New River Kinematics Unified Spatial Metrology Network (USMN)
- Element of the Spatial Analyser software
- Combines measurement systems
- Allows for scaling at the bundle adjustment stage
- Effectively uses the instrument “error footprint” to assess measurement performance
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- Simulation tools to optimize job layout
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Uncertainty Analysis Example
•
Combining measurement systems
 2 Laser Trackers
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Common
Targets
Pos0
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Pos1
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Uncertainty Analysis Example
Network Solution: USMN
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•
Combining measurement systems
 2 Laser Trackers
– Optimize the instrument locations
– Apply scale and instrument “error footprint”
– Generate a weighted composite coordinate group
– Generate a valid Uncertainty statement and Uncertainty
fields for each composite point.
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Uncertainty Analysis Example
Network Solution: USMN
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• 2 Laser Trackers After Combination
Composite pt r3,
and uncertainty field
Pos0
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Pos1
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Uncertainty Analysis Example
Network Solution: USMN
• Add a 3rd tracker to the measurement chain
Pos2
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Common
Targets
Pos0
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Pos1
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Uncertainty Analysis Example
Network Solution: USMN
• Uncertainty propagation: open loop survey
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Pos2
Fixed
Reference
Pos0
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Pos1
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Uncertainty Analysis Example
Network Solution: USMN
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• Application: A330/340 Stage 01 Assy Jig
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Uncertainty Analysis Example
Network Solution: USMN
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• Application: A330/340 Stage 01 Assy Jig
OTP’s
ERS points
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Uncertainty Analysis Example
Network Solution: USMN
• Application: A330/340 Stage 01 Assy Jig
• Add a 4th laser tracker to the network!
Down 39%
Down 50%
Down 64%
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Down 66%
Down 54%
Down 56%
Down 66%
OTP’s
ERS points
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Additional USMN and SA benefits
• Pre and post tool design simulations to optimise the network
• Produce uncertainty statements which effectively define the jig build and verification
process capability index (CPK)
• Effective use of the uncertainty statements to challenge legacy tolerances or define
the new standard for new programs
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• Instrument angular measurement capability can be assessed and monitored
• Standardise and automate data gathering and reporting through use of SA
measurement plans (MP)
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Best practice statements
Process so far has yielded:
• Pre plan/optimise job using simulation tools
• Consider U for measurement tolerances
• Minimise hidden point projection length
• Minimise target distance from the laser tracker
• Measure multiple observations on each point
• Try to employ good intersection geometry
• Always try to close the survey loop
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• Overlap targets between positions by 80% - 100%
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Questions??
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© AIRBUS UK LTD. All rights reserved. Confidential and
proprietary document.
This document and all information contained herein is the sole
property of AIRBUS UK LTD. No intellectual property rights
are granted by the delivery of this document or the disclosure
of its content. This document shall not be reproduced or
disclosed to a third party without the express written consent
of AIRBUS UK LTD. This document and its content shall not
be used for any purpose other than that for which it is
supplied.
The statements made herein do not constitute an offer. They
are based on the mentioned assumptions and are expressed
in good faith. Where the supporting grounds for these
statements are not shown, AIRBUS UK LTD will be pleased to
explain the basis thereof.
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AIRBUS, its logo, A300, A310, A318, A319, A320, A321,
A330, A340, A350, A380, A400M are registered trademarks.
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