Development of a machine vision system for the quality control of transparent components with optical features: Shown on injection moulded single use test stripes
2024 (English) Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE credits
Student thesis
Abstract [en]
The inspection of production parts is a difficult, tedious and exhausting task, usually per-formed by human experts. Especially when it comes to small features, a manual inspection can be insufficient and susceptible to errors. To aid the quality control of transparent injec-tion molded test stripe components and validate the color accuracy of installed reaction pa-pers, a machine vision system is designed and build for the automatic inspection of the given parts. This work applies a defect detection and classification approach which makes use of the difference in appearance of certain defect types depending on the way they are illumi-nated. In a following steps filters and other image processing methods are used to separate the defect from the rest of the image. For each defect type, a specific lighting method and processing approach is chosen, which allows it to filter out all other defects. This approach is complemented by a convolutional neural network, trained for the classification of the test stripe components into ok and nok parts. For the task of color validation, a color calibration algorithm using a color chart is implemented and used as a basis for a referencing approach. In this approach the acquired color values of the sample are compared to a reference table, which allows it to translate them into pH or nitride values.The resulting system is capable of classifying the injection molded components with an accuracy of over 98%, while classifying defects into dust, scratches, surface defects, distor-tions and inclusions. Working with the Lab color space, the implemented color validation achieves a root-mean square error of 6.35 for L, 2.77 for a and 4.36 for b, which translates to an error of 0.2 when tested on a pH sample.
Place, publisher, year, edition, pages 2024. , p. 26
Keywords [en]
Machine Vision, Defect detection, Defect Classification, Color Calibration
National Category
Mechanical Engineering Electrical Engineering, Electronic Engineering, Information Engineering
Identifiers URN: urn:nbn:se:hv:diva-21464 Local ID: EXM903 OAI: oai:DiVA.org:hv-21464 DiVA, id: diva2:1850155
Subject / course Robotics
Educational program Master i robotik och automation
Supervisors
Examiners
2024-04-192024-04-092024-04-19 Bibliographically approved