Book Description

Displacement Measurement constitutes one of the most challenging problems in Mechanical and Civil Engineering, crossing very different applications and scales, from biomechanical and mechanical components to long span bridges and aerospace structures.

The diversity of applications, test conditions, displacement ranges and accuracy demands have contributed to a continuous development in measurement technologies and sensors since the establishment of Experimental Mechanics to the present days. At the same time, the increasing potential of displacement measurement in the context of structural observation and health monitoring has fostered the dissemination of measurement techniques across different areas of knowledge.

Displacement Measurement is the second contribution from the authors for the book series Measurement of Physical and Chemical Quantities to be published by IFSA Publishing, focusing on techniques and sensors to measure physical and chemical quantities.

Addressed to researchers with different backgrounds, the book presents in an accessible and concise form the various physical principles and associated techniques for displacement measurement. These comprehend the most classical techniques, based on the measurement of variations with displacement of electrical resistance, capacitance and inductance, or else optical techniques using electromagnetic, acoustic or interference wave measurements, still with open fields of research and offering a wide range of applications. Complementarily and in a clear and systematic way, the authors discuss the advantages and limitations of the various techniques and provide information on the ranges of measurements and associated accuracy.

Written by researchers and academics from the University of Porto with extensive backgrounds in Mechanical and Electronic Engineering, the book Displacement Measurement is presented in a didactic, fluid and synthetic form and constitutes therefore an important instrument for the dissemination of knowledge in the various areas of research requiring the observation and health monitoring.


The present book entitled Displacement Measurement is the second title in the series 'Measurement of Physical and Chemical Quantities'. This volume is devoted to the measurement of displacement considering its relevance in the engineering field. Invited authors also contribute to specific topics adding valuable perspectives.

The book starts by introducing the elementary concepts of position, displacement and distance. A brief overview of the history of length measurement is also included. Then the main traditional experimental methodologies for measuring displacement are described.

In the following chapters resistive and inductive transducers are introduced as well as digital encoders and transducers based in optical fibre. The chapters also include the basic instrumentation knowledge and techniques associated with the types of transducers described.

Chapter 1. Elementary Concepts, conveys the fundamentals of position, displacement and distance concepts and introduces a brief history of their units. A broad synthesis of the working principles used in the area is offered.

Chapter 2. Potentiometer Transducers, deals with the working principle of the most elementary transducer type for middle range displacements as well as its most relevant characteristics and highlights simple technical instrumentation details.

Chapter 3. Inductive Transducers, describes the fundamentals of the working principles of two inductive transducers, the LVDT and the Foucault Current types. It also details their fundamental specifications concerning signal instrumentation and conditioning as well as different techniques that should be applied in order to minimize the main sources of measurement error. Along the chapter the use of graphical representation is used to clarify many aspects of signal specification.

Chapter 4. Digital Encoders, explains how digital encoders of absolute and incremental types work. Their main characteristics are also mentioned.

Chapter 5. Displacement Transducers Based in Optical Fibre Sensors, is the contribution of the invited authors José Luís Santos, Luís Alberto Ferreira, Francisco Moita Araújo. The chapter offers insights on fibre optic based displacement sensors, providing a general classification of contact and non-contact types and describing sensor interrogation techniques and general characteristics.

The authors hope to have contributed to cover both the main concepts and the technical information on the topic of displacement measurement. This contribution has been clearly enriched by the involvement of the invited authors.