United States of America As Represented by the Administrator of Nasa

Christopher D Immer

Anthony Eckhoff

Pedro J Medelius

Jose M Perotti

Stanley O Starr

Richard T Deyoe

John Lane

A device and procedure for checking the health of a pressure transducer in situ is provided. The procedure includes measuring a fixed change in pressure above ambient pressure and a fixed change in pressure below ambient pressure. This is done by first sealing an enclosed volume around the transducer with a valve. A piston inside the sealed volume is then driven forward, compressing the enclosed gas, thereby increasing the pressure. A fixed pressure below ambient pressure is obtained by opening the valve, driving the piston forward, sealing the valve, and then retracting the piston. The output of the pressure transducer is recorded for both the overpressuring and the underpressuring. By comparing this data with data taken during a preoperative calibration, the health of the transducer is determined from the linearity, the hysteresis, and the repeatability of its output. The further addition of a thermometer allows constant offset error in the transducer output to be determined.

Thermodynamic pressure/temperature transducer health check

A multi-sensor transducer and processing method allow insitu monitoring of the senor accuracy and transducer 'health'. In one embodiment, the transducer has multiple sensors to provide corresponding output signals in response to a stimulus, such as pressure. A processor applies individual weight factors to reach of the output signals and provide a single transducer output that reduces the contribution from inaccurate sensors. The weight factors can be updated and stored. The processor can use the weight factors to provide a 'health' of the transducer based upon the number of accurate versus in-accurate sensors in the transducer.

Multi sensor transducer and weight factor

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Merritt Island, FL, United States of America

Christopher D Immer