LINEAR POSITION SENSOR TECHNOLOGY

Linear position sensor technology



Linear Displacement Sensor

Abstract

In this study we try to explore the concept of Linear Displacement Sensor in a holistic context. The main focus of the research is on linear position sensor and its relation with pitch angle ? of blade of a vertical axis wind turbine. This paper discusses the overview of the Linear Displacement Sensor. The paper also analyses the technical requirements and features to be considered in Linear Displacement Sensor in order to sense pitch angle ? of blade of a vertical axis wind turbine. In this paper a new encoder-like capacitive sensor, referred to as the contact-type linear encoder-like capacitive displacement sensor (CLECDS), has been proposed. The research also analyzes many aspects of this advance technology and tries to gauge its effect on sensing pitch angle ?.

Introduction

Capacitive displacement sensors are useful devices for measuring small displacements due to their high sensitivity and insensitivity to changes in temperature and magnetic field and . These sensors are comprised of two parallel conducting plates and are classified into two categories depending on whether the detecting variable is the spacing between the plates or the area of overlap of the plates. (Bonse, 2009, 266) Spacing variation-type capacitive sensors determine displacements based on the change in capacitance with varying the gap between the plates. In general, sensors of this type measure the relative motion of the two plates in the direction perpendicular to the plates by monitoring the signal obtained from an electrical circuit for detecting variations in electrical capacitance. These sensors can detect displacements down to the sub nanometer range, but are limited to maximum displacements of a few hundred micrometers (Bonse, 2009, 266).

The area of ??change in type of capacitive sensors, on the other hand, determining the movements based on variations in the ability to vary the overlap area of two parallel conducting plates separated by a constant space. Thus sensors of this type measure the transverse displacement parallel to the two plates. This configuration gives these sensors a longer measuring range but lower sensitivity than spacing variation-type sensors (Bonse, 2009, 266).

Various attempts have been made to improve the sensitivity of the area variation-type sensors. For example, a linear encoder-like capacitive sensor was developed and in which, rather than using two flat plates such as in traditional area variation-type sensors, scaled conducting bars were placed on the two parallel substrates. In this sensor configuration, horizontal translation of one plate with respect to the other plate with a constant gap gives rise to periodic variations in capacitance caused by changes in the overlapped area of the bars on the two facing substrates. These capacitive sensors have the advantage that they can give high resolution, where the resolution attained is inversely propositional to the pitch size of a series of the bars. In the present work we propose a contact-type linear encoder-like capacitive displacement sensor (CLECDS). The proposed sensor design is based on traditional linear encoder-like capacitive displacement sensor consists of two substrates with a series ...