Understanding Smart Sensors - Nomads.usp

Smart Sensor Basics 3Table 1.1Mechanical MeasurementsMeasurementDisplacement/positionTemperaturePressureVelocity (linear/angular)AccelerationForceTorqueMechanical impedanceStrainFlowHumidityProximityRangeLiquid levelSlipImminent collisionTypical/Common TechniquesVariable reluctance, Hall effect, optoelectronicThermistor, transistor base-emitter voltage (Vbe)Piezoresistive, capacitiveVariable reluctance, Hall effect, optoelectronicPiezoresistive, capacitive, piezoelectricPiezoresistiveOptoelectronicPiezoresistivePiezoresistive∆ pressure, or delta pressureResistive, capacitiveUltrasonicRadarUltrasonicDual torqueRadarThe definition of smart sensor (intelligent transducer) has not been aswidely accepted and is subject to misuse. However, an Institute of Electricaland Electronics Engineers (IEEE) committee has been actively consolidatingterminology that applies to microelectronic sensors. The recently approvedIEEE 1451.2 specification defines a smart sensor as a sensor “that providesfunctions beyond those necessary for generating a correct representation of asensed or controlled quantity. This function typically simplifies the integrationof the transducer into applications in a networked environment” [2]. That definitionprovides a starting point for the minimum content of a smart sensor.Future smart sensors will be capable of much more, and additional classifications(e.g., smart sensor type 1) may be required to differentiate the products.Chapter 12 addresses the IEEE-approved smart transducer interface for sensorsand actuators that establishes a standard for transducer-to-microprocessor communicationprotocols in a transducer electronic data sheet (TEDS) format.That standard and others will provide further definition and differentiation for