Air data system fault modeling and detection

Aircraft pitot-static probes are essential to airspeed and altitude measurements and safe flight. Measurement integrity is typically achieved via sensor hardware redundancy and a voting system. Hardware redundancy imposes a cost and payload penalty. This paper investigates an analytical alternative to hardware redundancy requiring a mathematical model of faulted and unfaulted pitotstatic probes. The most common probe faults-debris, ice, or water blockages-are modeled using physical air data relationships and experimental wind tunnel data. These models are used with a linear model of the NASA GTM aircraft at one flight condition to design robust fault detection filters. Two linear H-infinity filters are designed to detect faults, reject disturbances, and provide robustness to model errors. Performance is evaluated using experimentally derived fault models with nonlinear aircraft simulations that incorporate actuator uncertainty. (C) 2013 Elsevier Ltd. All rights reserved.