Distributed Large-Scale Dimensional Metrology

Abstract

The last decades have shown great improvements in the field of engineering dimensional metrology. The introduction of modern computational systems, ever more compact microelectronic devices and innovative materials have given a significant impulse to the accuracy and application of traditional devices. Recent developments have included applications both for extremely small-sized and for extremely large-sized objects. Following this, two new branches of dimensional metrology have demonstrated their maximal potentiality: ‘‘nano-metrology'', related to the measurement of extremely small objects, and ‘‘large-scale dimensional metrology'' (LSM), which refers to the measurement of large engineering structures. To begin with nano-metrology, the current widespread success can be ascribed to the new generations of scanning electron microscopes (SEMs) and, even more, to atomic force microscopes (AFMs), which allow us to obtain precise and accurate measurements of very small elements and structures. On the other hand, large-scale dimensional metrology has reached its historic turning point with the introduction of modern very accurate and flexible optical systems. The aim of the present book is to trace and discuss the most recent developments in the field of LSM, with particular attention to so-called distributed systems. Special emphasis is given to topics concerning sensor positioning, system calibration and self-diagnostics, which represent the key elements for the correct functioning of these systems. This book is directed at academics, practitioners and consultants who are responsible for designing the best solutions and tools to manage LSM processes. The text materials can be used in programs for professional practitioners, including quality engineers, manufacturing engineers and procurement specialists. Professionals may also use the material for self study. This book is organized in eight chapters. Chapter 1 introduces large-scale metrology, discussing its goal and giving a short summary of classical instruments. Some of the most recent instruments are then introduced providing a structured classification. turning point for LSM distributed systems. Chapter 3 is dedicated to the technical description of Mobile Spatial coordinate Measuring System (MScMS), a prototypal system developed from the research activity carried out at the Industrial Metrology and Quality Engineering Laboratory of Department of Production Systems and Business Economics (DISPEA) at the Politecnico di Torino. The UltraSound (US) version (MScMS-I) and the InfraRed (IR) version (MScMS-II) are described in detail. A general comparison between these two versions and other existing systems is also presented. Chapter 4 deals with network device positioning and coverage of the measuring area, while Chaps. 5, 6 and 7, respectively approach the topics of system calibration, system on-line self-diagnostics and improvement of system metrological performance. Uncertainty budget evaluation is treated in Chap. 8. All these chapters face the respective topics from a general point of view, enriching the explanation by introducing some practical examples