CAD based Computer Vision for Pose Determination of Wooden Parts

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Title: CAD based Computer Vision for Pose Determination of Wooden Parts
Author: Kulkarni, Parikshit S.
Advisors: Dr. Denis R. Cormier, Chair
Dr. C. G. Healey, Member
Dr. Y. S. Lee, Member
Abstract: Furniture manufacturers today have to deal with the conflicting objectives of increased product variety with reduced lead-time and inventory levels. The prevalentsentiment in the industry is a build to order production strategy, which tends to increase the production costs. Furniture makers are hence looking for technologicalsolutions to counter these issues. Fixture-less machining on CNC routers is an alternative gaining prominence among manufacturers to reduce setup times andincrease productivity. However, in the absence of locating pins for mounting the parts, the orientation and part placement becomes critical and small errors canincrease rejection rates. Updating the CNC part programs after determining the exact orientation and location of the part blanks is a likely solution. This thesisrepresents an effort to develop a computer vision based system to enable this. Some of the popular techniques in computer vision for object recognition were henceimplemented. These however did not prove worthwhile as the efficacy of the algorithms was undermined by the texture from wood grains. A template matchingprocedure was identified as being better suited for the purpose because of its inherent tolerance for noise. The generation of the template to account for hidden linesand actual projected lengths, both functions of the viewing direction and camera location, was however the biggest challenge. The fact that most furnituremanufacturers have a very large product range that needs machining on the router compounds the problem. A novel CAD based template generation algorithm washence proposed and implemented. The developed algorithms enabled orientation determination with a negligible error, and the average error in locating the part wasless than 0.2 percent. The approach was therefore found to have a potential in reducing the lead times while specifying tighter tolerances to reduce raw-materialconsumption. Finally, some future work to completely automate the process and to extend the applicability of the approach has been proposed.
Date: 2001-07-23
Degree: MS
Discipline: Industrial Engineering
URI: http://www.lib.ncsu.edu/resolver/1840.16/2361


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