Flexible Optical Metrology Strategies for the Control and Quality Assurance of Small Series Production R. Schmitt1, A. Pavim2 Laboratory for Machine Tools and Production Engineering WZL at the RWTH Aachen University, Steinbachstrasse 19, 52074 Aachen, Germany ABSTRACT The demand for achieving smaller and more flexible production series with a considerable diversity of products complicates the control of the manufacturing tasks, leading to big challenges for the quality assurance systems. The quality assurance strategy that is nowadays used for mass production is unable to cope with the inspection flexibility needed among automated small series production, because the measuring strategy is totally dependent on the fixed features of the few manufactured object variants and on process parameters that can be controlled/compensated during production time. The major challenge faced by a quality assurance system applied to small series production facilities is to guarantee the needed quality level already at the first run, and therefore, the quality assurance system has to adapt itself constantly to the new manufacturing conditions. The small series production culture requires a change of paradigms, because its strategies are totally different from mass production. This work discusses the tight inspection requirements of small series production and presents flexible metrology strategies based on optical sensor data fusion techniques, agent-based systems as well as cognitive and self-optimised systems for assuring the needed quality level of flexible small series. Examples of application scenarios are provided among the automated assembly of solid state lasers and the flexible inspection of automotive headlights. Keywords: small series production, flexible metrology, optical metrology, sensor data fusion, agent-based systems, cognition, knowledge-based systems and self-optimisation

1. INTRODUCTION Today, many factors are impelling the improvements of production processes. The customers become more exigent in relation to the product personification and quality, which results in a demand for smaller and more flexible production series with a considerable diversity of components. Consequently, the control of the manufacturing tasks becomes more complicated, leading to big challenges for the quality assurance systems. This work starts discussing about the production in small series and its inspection requirements, which state a big challenge and demand new research efforts for achieving cost-effective as well as quality-assured production systems at the same time. In order to face this challenge, quality assurance systems must be conceived extremely flexible, being able to constantly adapt themselves to the working environment and autonomously accomplish their planning, inspection, measurement and decision taking goals. Some key technologies are of high relevance to achieve such goal: optical metrology for a non-destructive inspection of the product and process features; sensor data fusion for flexibly dealing with higher product variety and providing a more robust evaluation of the measured data; software agents for the flexible and autonomous handling of complex manufacturing and inspection tasks; cognition and knowledge-based systems for the intelligent analysis of the acquired data, decision taking and adaptivity of the system; as well as selfoptimisation for enabling technical systems to follow autonomously new goals and adapt themselves to the environment. These topics are introduced in the following sections of this paper, discussing their benefits for facing the challenges of the small series production. Finally, possible application scenarios of such key technologies are discussed among the automated assembly of a diode-pumped solid-state laser and the flexible inspection of automotive headlights.

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Prof. Dr.-Ing. Robert Schmitt; [email protected]; Tel. +49 241 80-20283, Fax: +49 241 80-22193 Scholarship holder of the Brazilian CNPq