Page 114 - Electric Drives and Electromechanical Systems
P. 114
4
Velocity and position transducers
Chapter outline
4.1 The performance of measurement systems ............................................................................ 108
4.1.1 Random errors................................................................................................................... 110
4.1.2 Systematic errors ............................................................................................................... 111
4.1.3 Digital-system errors ......................................................................................................... 112
4.1.4 Analogue-digital and digital-analogue conversion errors............................................ 114
4.1.5 Dynamic performance ...................................................................................................... 115
4.1.6 Errors introduced by the process..................................................................................... 115
4.2 Rotating velocity transducers.................................................................................................... 116
4.2.1 Brushed d.c. tachogenerators .......................................................................................... 116
4.2.2 Brushless d.c. tachogenerators......................................................................................... 117
4.2.3 Incremental systems.......................................................................................................... 118
4.2.4 Electromechanical pulse encoders................................................................................... 119
4.3 Position transducers ................................................................................................................... 119
4.3.1 Brushed potentiometers................................................................................................... 119
4.3.2 Linear variable differential transformers - LVDT........................................................... 119
4.3.3 Resolvers............................................................................................................................. 121
4.3.4 Inductosyn.......................................................................................................................... 124
4.3.5 Optical position sensors.................................................................................................... 126
4.4 Installation considerations for position and velocity transducers ........................................ 130
4.4.1 Mechanical installation..................................................................................................... 130
4.4.2 Electrical interconnection................................................................................................. 132
4.4.3 Determination of datum position................................................................................... 132
4.5 Summary...................................................................................................................................... 133
References........................................................................................................................................... 134
Within the manufacturing tolerances smaller than 5 mm are common place, requiring
measurement systems of similar accuracy and precision. Any error within the machining
of a component is becoming increasing costly, due to an increasing scrappage rate and
time lost in re-machining the component, to the manufacturer, this has led to consid-
erable research in metrology and in how measurements can made (Smith, 2016) and
traced through the manufacturing processes to remove uncertainty (Mutilba et al., 2017).
Electric Drives and Electromechanical Systems. https://doi.org/10.1016/B978-0-08-102884-1.00004-2 107
Copyright © 2020 Elsevier Ltd. All rights reserved.
