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Machine Vision - Based Alignment for Vehicle Wheels: Space to - - PowerPoint PPT Presentation
Machine Vision - Based Alignment for Vehicle Wheels: Space to - - PowerPoint PPT Presentation
Visualiner 3D Machine Vision - Based Alignment for Vehicle Wheels: Space to Factory to Garage Donald J. Christian Snap-on Diagnostics San Jose, California, USA Presented at Automekanika XV - Frankfurt 1 Visualiner 3D wheel alignment
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Conventional Wheel Aligner Instrumentation
Front
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What is the 3D What is the 3D Visualiner Visualiner ? ?
l Solid-state cameras and wheel targets l Modern machine vision software l Array of high-power microprocessors l 3-dimensional workstation software l 3-D graphical user interface / presentation l Database of adjustment illustrations
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Why machine vision? Benefits: Why machine vision? Benefits:
l The aligner is faster and more productive l More reliable, cheaper to operate l Easier to operate, physically and cognitively l High precision l Easier for technicians to learn l More capable geometric instrumentation
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Benefits: Benefits: It’s faster.
It’s faster.
l In field use it’s almost twice as fast
– 6 minutes on 3D-V, 11 minutes on conventional.
Measured from drive-in to print-out on 3000 cars
– Greater technician productivity – More alignments per bay per day
l No jacking. The vehicle stays on its wheels. l Built-in expert help. l Graphic illustrations and textual
descriptions for all adjustments.
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Benefits: Benefits: More reliable, cheaper to operate
More reliable, cheaper to operate
l No calibration after it’s installed l No sensitive electronics in the heads
– No downtime due to damaged heads
l No wires to get tangled, broken, or lost l No radio-frequency interference l No batteries to recharge or wear out l No electronics under the wheels (turntables)
to get dirty and rusty
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Benefits: Benefits: Easier to operate.
Easier to operate.
l Light-weight heads. Easy to carry and easy
to mount
– Less physical effort, greater productivity
l No interference from under-car obstructions
– Spoilers or air dams – Low exhaust pipes – Custom running boards – Low-rider vehicles
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Benefits: Benefits: High Precision
High Precision
l Wheels stay on the ground during
measurement
– real road conditions, not laboratory conditions
l Full lock-to-lock caster swings, T-O-O-T l No caster distortion due to vehicle yaw
during caster swing
l High resolution electronic cameras
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Benefits: Benefits: It’s easier for mechanics to learn
It’s easier for mechanics to learn
l Ergonomic, intuitive graphical interface
– Alignment meters displayed in 3-D
l All vehicle adjustments shown graphically
– Exclusive 3-D orientation indicator simplifies diagrams
l Expert, context-sensitive help is 1 or 2
keystrokes away at all times
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Graphic adjustment illustrations Graphic adjustment illustrations
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3 3-
- Dimensional meter display
Dimensional meter display
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Benefits: Benefits: New vehicle measurements
New vehicle measurements
l Absolute wheel base distances l Absolute rim-to-rim track widths l Individual wheel side-set l Symmetry about vehicle center line l
- ther geometries previously impractical
with conventional instruments . . .
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Why is 3D alignment now possible ? Why is 3D alignment now possible ?
l Availability of great computer power
– Pentium processors, faster clock speeds – Parallel microprocessor arrays
l High resolution solid state cameras l New machine vision technologies
– Stochastic subpixel interpolation techniques – High-precision microelectronics manufacturing – Well-developed alignment techniques
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Machine Vision Architecture Machine Vision Architecture
Secondary Image Buffers Camera MicroController (Moto HC6811) Primary Image Buffer MIPS Image Analysis Microprocessors 3-D Graphics Workstation
Camera
Multiprocessor Array
Camera
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Target Design Target Design
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Camera Views Camera Views
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Target distortion: rotation Target distortion: rotation
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Target distortion: perspective Target distortion: perspective
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Target motion infers axis of rotation Target motion infers axis of rotation
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Cycloidal Cycloidal motion of targets identifies motion of targets identifies the axes of rotation the axes of rotation
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Image Analysis Image Analysis
1 2 3 4 5 6 7 8 9
List of Centroid Coordinate Pairs
# X Y 1 251.768 473.112 2 207.449 476.432 3 231.956 573.020 4 266.712 492.909 5 227.193 481.409 6 . . . 7 . . . 8 . . .
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Multiple measurements per image for Multiple measurements per image for high total accuracy high total accuracy
A B C D
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Vehicle wheel alignment is just the latest application Vehicle wheel alignment is just the latest application
- f machine vision to precision alignment . . .
- f machine vision to precision alignment . . .
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