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” is really “axle geometry measurement” 6 5 3 4 1 2 2

Visualiner 3D Conventional Wheel Aligner Instrumentation Front 3

Visualiner 3D 4

Visualiner 3D 5

Visualiner 3D What is the 3D Visualiner Visualiner ? ? What is the 3D 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 6

Visualiner 3D 7

Visualiner 3D 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 8

Visualiner 3D It’s faster. Benefits: It’s faster. Benefits: 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. 9

Visualiner 3D More reliable, cheaper to operate Benefits: More reliable, cheaper to operate Benefits: 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 10

Visualiner 3D Easier to operate. Benefits: Easier to operate. Benefits: 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 11

Visualiner 3D High Precision Benefits: High Precision Benefits: 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 12

Visualiner 3D It’s easier for mechanics to learn Benefits: It’s easier for mechanics to learn Benefits: 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 13

Visualiner 3D Graphic adjustment illustrations Graphic adjustment illustrations 14

Visualiner 3D 3- -Dimensional meter display Dimensional meter display 3 15

Visualiner 3D New vehicle measurements Benefits: New vehicle measurements Benefits: l Absolute wheel base distances l Absolute rim-to-rim track widths l Individual wheel side-set l Symmetry about vehicle center line other geometries previously impractical l with conventional instruments . . . 16

Visualiner 3D 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 17

Visualiner 3D Machine Vision Architecture Machine Vision Architecture Camera Camera Camera MicroController (Moto HC6811) Primary Image Buffer MIPS Image Secondary Image Analysis Buffers Microprocessors 3-D Graphics Multiprocessor Array Workstation 18

Visualiner 3D Target Design Target Design 19

Visualiner 3D Camera Views Camera Views 20

Visualiner 3D Target distortion: rotation Target distortion: rotation 21

Visualiner 3D Target distortion: perspective Target distortion: perspective 22

Visualiner 3D Target motion infers axis of rotation Target motion infers axis of rotation 23

Visualiner 3D Cycloidal motion of targets identifies motion of targets identifies Cycloidal the axes of rotation the axes of rotation 24

Visualiner 3D Image Analysis Image Analysis List of Centroid Coordinate Pairs 4 # X Y 3 1 251.768 473.112 5 2 207.449 476.432 1 2 3 231.956 573.020 6 4 266.712 492.909 7 5 227.193 481.409 8 9 6 . . . 7 . . . 8 . . . 25

Visualiner 3D Multiple measurements per image for Multiple measurements per image for high total accuracy high total accuracy B A C D 26

Visualiner 3D Vehicle wheel alignment is just the latest application Vehicle wheel alignment is just the latest application of machine vision to precision alignment . . . of machine vision to precision alignment . . . 27

Visualiner 3D Where can I get my car aligned with Where can I get my car aligned with machine vision ? machine vision ? Look for a local wheel service shop that uses the “Visualiner 3D”, distributed by the John Bean Co. (a division of Snap-on) 28