Pore Detection in Small Diameter Bores The University of Michigan, Ann Arbor NSF Engineering...

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Pore Detection in Small Diameter Bores The University of Michigan, Ann Arbor NSF Engineering Research Center for Reconfigurable Manufacturing Systems

Transcript of Pore Detection in Small Diameter Bores The University of Michigan, Ann Arbor NSF Engineering...

Pore Detection in Small Diameter Bores

The University of Michigan, Ann Arbor

NSF Engineering Research Center for

Reconfigurable Manufacturing Systems

NSF Engineering Research Center for Reconfigurable Manufacturing SystemsUniversity of Michigan College of Engineering

ERC Presentation Format # 2

Introduction

Pores above 500 micron inside small bores may cause leakage and other problem

Specifications:• Dimension: Φ 5-15 mm L 100-150 mm ( May be stepped and discontinuous) • Material: Aluminum• Pore Size: Φ < 1 mm

• Surface: Glossy

Φ15mm Φ5mm

100-150 mm

NSF Engineering Research Center for Reconfigurable Manufacturing SystemsUniversity of Michigan College of Engineering

ERC Presentation Format # 3

Project goals

1. In-line inspection of the inner surface of small bores of power train parts

2. Detect and locate pores lager than 1mm diameter inside a small bore

NSF Engineering Research Center for Reconfigurable Manufacturing SystemsUniversity of Michigan College of Engineering

ERC Presentation Format # 4

Progress

• Stage 1. Background investigation (April, 2007 )

• Stage 2. Preliminary study (May, 2007)

• Stage 3. System integration (June, 2007)

• Stage 4. Image processing and porosity analysis (July-Now, 2007)

NSF Engineering Research Center for Reconfigurable Manufacturing SystemsUniversity of Michigan College of Engineering

ERC Presentation Format # 5

Sight Pipe System

X Y motion stage

Z rotary stage

CCD

Sight Pipe

Sample

Side and top view of the system

NSF Engineering Research Center for Reconfigurable Manufacturing SystemsUniversity of Michigan College of Engineering

ERC Presentation Format # 6

“Paper Bore” image

13 mm Diameter

Real Bore image

The shadow lines appears

Scanning results

NSF Engineering Research Center for Reconfigurable Manufacturing SystemsUniversity of Michigan College of Engineering

ERC Presentation Format # 7

Scanning result after alignment

After alignment

Before alignment

Large intensity variance

small intensity variance

NSF Engineering Research Center for Reconfigurable Manufacturing SystemsUniversity of Michigan College of Engineering

ERC Presentation Format # 8

Alignment of Camera and motion stage

• Step1- Focus the camera onto a target point at a close distance and center the target using linear adjustments.

• Step2- Use motion stage to move the camera to the further distance and center the target using angular adjustments.

Step3- Repeat steps 1 and 2 until the targets are centered in the same position.

NSF Engineering Research Center for Reconfigurable Manufacturing SystemsUniversity of Michigan College of Engineering

ERC Presentation Format # 9

Aligning the Bore axis

• Step1-Focus on front of the bore and find the center of the circular opening.

• Step2-Focus on the back of the bore and find the center of a circular ring.

• Step3-Align angular and linear positioning of the bore until the two reference circles are centered with the camera.

NSF Engineering Research Center for Reconfigurable Manufacturing SystemsUniversity of Michigan College of Engineering

ERC Presentation Format # 10

Straightness and angular tolerance for aligning the Bore

• The bore must be properly aligned to provide a low intensity variance for the unwrapping zone.– Straightness should be

within ~0.18 mm in each direction

– Angular error should be within ~670 arcsecs

Standard Deviation due to the Linear Offset

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-0.15 -0.1 -0.05 0 0.05 0.1 0.15 0.2 0.25

Shift Distance (mm)

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Standard Deviation Due to Angular Offset

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-1000 -800 -600 -400 -200 0 200 400

Angular Offset (arcsec)

Sta

ndard

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NSF Engineering Research Center for Reconfigurable Manufacturing SystemsUniversity of Michigan College of Engineering

ERC Presentation Format # 11

Current Work

1. Software interface improvement User-Friendly interface Well organized program with clear comments

2. Porosity analysis using Labview – Detect pores with different size

– Indicate the location of the pores

– Filter the pores as needed (By size, location and so on)

– Provide statistic table

3. Redesign mounting structure for the sight pipe system to add one degree of freedom in vertical direction

NSF Engineering Research Center for Reconfigurable Manufacturing SystemsUniversity of Michigan College of Engineering

ERC Presentation Format # 12

Some Algorithms

Sight Pipe + IMAQ image processing: Finding center polar unwrapping stitching

Motion control : Magnification = real width of line / pixel width of line*Pixel size

Total time of Scan = scanning distance/ motion velocity

Motion velocity= Width of sampling zone*Pixel size*Magnification / Sampling period

Finding the Pore:

Threshold Particle Filter Particle Analysis

NSF Engineering Research Center for Reconfigurable Manufacturing SystemsUniversity of Michigan College of Engineering

ERC Presentation Format # 13

Image Processing

1. A background correction threshold is applied to the entire image.

– Background correction breaks the image up into smaller regions and searches for the darkest areas in each image.

2. The particles are then put through a particle filter based on the major axis of the best fit ellipse.

3. The image saved with particle information are loaded into a screen that allows the user to easily see the pores and their location based on the filter been chosen.

NSF Engineering Research Center for Reconfigurable Manufacturing SystemsUniversity of Michigan College of Engineering

ERC Presentation Format # 14

MINI CCD updating

51 degree field of view with normal lens

Inside view of a bore ( 13 & 30 mm diameter)

NSF Engineering Research Center for Reconfigurable Manufacturing SystemsUniversity of Michigan College of Engineering

ERC Presentation Format # 15

Fiber illumination for the MINI CCD

Fiber

MINI CCD

NSF Engineering Research Center for Reconfigurable Manufacturing SystemsUniversity of Michigan College of Engineering

ERC Presentation Format # 16

Next Steps

• Optimize the pore detection algorithms

• Improve the mounting structure of the sight pipe system

• Increasing the optical magnification to get higher resolution

• Upgrading the CCD and DAQ device for higher speed if necessary

• Continue the Mini CCD research