Position Sensors, 2nd edition

Book Preface

Since the publication of Linear Position Sensors, Theory and Application in 2004, another book by this author, society and industry worldwide have further continued to increase their reliance on the availability of accurate and current information from sensors. Timely access to information is critical to effectively meet the indication and control requirements of industrial processes, manufacturing equipment, household appliances, onboard automotive systems, and consumer products. A variety of technologies are used to address the specific sensing parameters andconfigurations needed to meet these requirements.

Since the advent of smart phones, the general public has begun to understand that sensors are involved in their daily lives. Many personal device applications rely on the onboard accelerometer, GPS capability, ambient light sensor, microphone, touch sensor, camera function, and other sensors that may be added in future designs. Sensors are used in cars to measure many safety‐ and performance‐related parameters, including throttle position, temperature, exhaust gas composition, suspension height, pedal position, transmission gear position, and vehicle acceleration. In clothes washing machines, sensors measure water level and temperature, load size, and drum position variation. Industrial process machinery requires the measurement of position, velocity, and acceleration, in addition to chemical composition, process pressure, flow rate, temperature, and so on.

More recent sensor designs often include the capability of communication over a shared bus, wireless communication, and communication via the Internet and personal devices. This will likely continue the trend toward greater ease of installation, additional performance features, and facilitation of routine and preventive maintenance.

Linear and angular/rotary position measurement comprises a large portion of the worldwide requirement for sensors. And so the original book on linear position sensors has been rewritten to include angular/rotary position sensors and update and expand the information on linear position sensors. Some chapters address position sensing technologies that have not been adequately described in any previous book. This book explains the theory and application of the technologies used in sensors for the measurement of linear and angular/rotary position, providing information important to sensor design in general. A chapter on sensor outputs and communication protocols is included and is applicable to all types of industrial sensors. Also included is information on electromagnetic interference, electrostatic discharge, and intrinsic safety.

There is often some hesitation in selecting the “proper” word—sensor or transducer—
since the definitions of the terms are somewhat overlapping in normal usage and any distinction is becoming less important. Chapter 1 presents a working definition of these and other, sometimes confusing, terms used in the field of sensing technology.

Chapter 2 explains how the performance of linear position transducers and sensors
is specified. Chapter 3 presents the various protocols for analog and digital signal output types. The remaining chapters present the theory supporting the prominent technologies in use in linear and angular/rotary position sensor and transducer products. Application guidance and examples are also included.