The Boeing Company
Method of ratiometric proximity sensing

Abstract:

Systems and methods for measuring an operating current and an operating voltage of an inductive proximity sensor in an improved manner. The proposed method is to measure and process the sensing parameters in a ratiometric way. A proximity sensing electronics unit receives an input signal from a proximity sensor that was derived by dividing the sensor's current by the sensor's supply voltage which produces that operating current. The division result, i.e., the quotient, is properly scaled to represent the sensor's state. The circuitry ratiometrically determines its operation status by eliminating common mode effects and variations of sensor state thresholds, allowing additional sensing parameters and health status to be measured and monitored without extending the operational range of the sensor.