LINEAR POSITION SENSORS
LINEAR POSITION SENSORS Theory and Application
DAVID S. NYCE
A JOHN WILEY & SONS, INC., PUBLICATION
Copyright © 2004 by John Wiley & Sons, Inc. All rights reserved. Published by John Wiley & Sons, Inc., Hoboken, New Jersey. Published simultaneously in Canada. No part of this publication may be reproduced, stored in a retrieval system, or transmitted in any form or by any means, electronic, mechanical, photocopying, recording, scanning, or otherwise, except as permitted under Section 107 or 108 of the 1976 United States Copyright Act, without either the prior written permission of the Publisher, or authorization through payment of the appropriate per-copy fee to the Copyright Clearance Center, Inc., 222 Rosewood Drive, Danvers, MA 01923, 978-750-8400, fax 978-750-4470, or on the web at www.copyright.com. Requests to the Publisher for permission should be addressed to the Permissions Department, John Wiley & Sons, Inc., 111 River Street, Hoboken, NJ 07030, (201) 748-6011, fax (201) 748-6008, e-mail:
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To Gwen, and our children Timothy, Christopher, and Megan, whose love and support helped me complete this project
CONTENTS
PREFACE
xi
1 SENSOR DEFINITIONS AND CONVENTIONS 1.1 1.2 1.3 1.4 1.5 1.6
Is It a Sensor or a Transducer? / 1 Position versus Displacement / 3 Absolute or Incremental Reading / 5 Contact or Contactless Sensing and Actuation / 5 Linear and Angular Configurations / 8 Application versus Sensor Technology / 8
2 SPECIFICATIONS 2.1 2.2 2.3 2.4 2.5 2.6 2.7 2.8 2.9 2.10
1
10
About Position Sensor Specifications / 10 Measuring Range / 10 Zero and Span / 11 Repeatability / 12 Nonlinearity / 13 Hysteresis / 19 Calibrated Accuracy / 21 Drift / 23 What Does All This about Accuracy Mean to Me? / 23 Temperature Effects / 25 vii
viii
CONTENTS
2.11 2.12 2.13 2.14 2.15 2.16 2.17
Response Time / 26 Output Types / 28 Shock and Vibration / 32 EMI/EMC / 34 P