AIWIN-a fast and jigless inspection technique for machined parts

Ravishankar, S and Dutt, HNV and Gurumoorthy, B (2012) AIWIN-a fast and jigless inspection technique for machined parts. International Journal of Advanced Manufacturing Technology, 62 (1-4). pp. 231-240. ISSN 1068-1086

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Precision inspection of manufactured components having multiple complex surfaces and variable tolerance definition is an involved, complex and time-consuming function. In routine practice, a jig is used to present the part in a known reference frame to carry out the inspection process. Jigs involve both time and cost in their development, manufacture and use. This paper describes 'as is where is inspection' (AIWIN), a new automated inspection technique that accelerates the inspection process by carrying out a fast registration procedure and establishing a quick correspondence between the part to inspect and its CAD geometry. The main challenge in doing away with a jig is that the inspection reference frame could be far removed from the CAD frame. Traditional techniques based on iterative closest point (ICP) or Newton methods require either a large number of iterations for convergence or fail in such a situation. A two-step coarse registration process is proposed to provide a good initial guess for a modified ICP algorithm developed earlier (Ravishankar et al., Int J Adv Manuf Technol 46(1-4):227-236, ). The first step uses a calibrated sphere for local hard registration and fixing the translation error. This transformation locates the centre for the sphere in the CAD frame. In the second step, the inverse transformation (involving pure rotation about multiple axes) required to align the inspection points measured on the manufactured part with the CAD point dataset of the model is determined and enforced. This completes the coarse registration enabling fast convergence of the modified ICP algorithm. The new technique has been implemented on complex freeform machined components and the inspection results clearly show that the process is precise and reliable with rapid convergence.

Item Type: Article
Additional Information: Copyright for this article belongs to M/s. Springer-Verlag
Uncontrolled Keywords: Machining;Engineering inspection;Computer-aided design; Manufacturing processes;Algorithms;Newton-Raphson method; Stochastic convergence
Subjects: ENGINEERING > Mechanical Engineering
Depositing User: Ms. Alphones Mary
Date Deposited: 25 Apr 2013 10:42
Last Modified: 25 Apr 2013 10:42

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