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Linear Position Sensors for Prognostics

IP.com Disclosure Number: IPCOM000240443D
Publication Date: 2015-Jan-30
Document File: 5 page(s) / 237K

Publishing Venue

The IP.com Prior Art Database

Abstract

Linear position sensors (LPS) are one of the most common types of position feedback sensors used in actuators for achieving control, guidance and stabilization in aerospace and other industrial applications. Sudden failure of these vital actuating systems could lead to multiple disadvantages. This paper provides a method for accurately predicting remaining life of the actuators based on monitoring operating cycle loads and number of stroke cycles using LPS. Adaptive remaining life assessment of actuators is performed using LPS by learning the pattern of usage cycles and based on that learning, recommendations for usage and maintenance actions are provided.

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Linear Position Sensors for Prognostics

Sivasubramanian Srinivasan, Gautham Ramamurthy, Vijayshekhar Araganji, Praveen Kathani

ABSTRACT

Linear position sensors (LPS) are one of the most common types of position feedback sensors used in actuators for achieving control, guidance and stabilization in aerospace and other industrial applications. Sudden failure of these vital actuating systems could lead to multiple disadvantages. This paper provides a method for accurately predicting remaining life of the actuators based on monitoring operating cycle loads and number of stroke cycles using LPS.  Adaptive remaining life assessment of actuators is performed using LPS by learning the pattern of usage cycles and based on that learning, recommendations for usage and maintenance actions are provided.

1. INTRODUCTION

Linear position sensors (LPS) play an important role in high reliability systems and systems where precise positioning is required. They are vital components in aerospace systems and industrial automation and control applications. LPS can be of different types such as linear contacting potentiometers, magnetostrictive sensors, linear encoders etc. Among these, linear variable differential transformers (LVDTs) are the most commonly used position feedback sensors for control, guidance and stabilization. LPS find their application in diverse set of systems such as flight control, automobiles, off-road vehicles, gaming machines and industrial applications such as oil and gas, paper and pulp. Sudden failure of these LPSs acting as feedback sensors in actuating devices in important applications could lead to major disastrous consequences. Their failure can lead to unscheduled equipment maintenance, discomfort to the user and even death in extreme cases. Hence there is a need for predicting their failure in advance so that suitable measures could be taken to avoid these consequences. Early prediction of failures could help mitigate catastrophic failures, eliminate break down maintenance and improve system availability. Prognostic technologies for actuators work by monitoring operating cyclic loads and number of stroke cycles (Actuator RAM strokes). But the main challenge in this approach is that the load peaks and stroke cycles are expected to vary randomly in each application which makes failure prediction challenging. Hence it is highly desirable to accurately predict the remaining life of actuators considering the cumulative effects of randomly varying loads and stroke amplitudes.

2. PROPOSED SOLUTION OF THE PROBLEM

For providing useful prognostics on actuators, their estimated residual life needs to be tracked over time and made available whenever user queries for the same. Out of ordinary conditions like static loading, exceeding of nominal loads, limit loads and ultimate loads are detected and marked. The patterns of usage cycles (load as well as stroke cycles) are studied over time. Some of the main failure modes for actuators that are con...