Fault Detection, Isolation and Reconfiguration in Presence of Incipient Sensor Faults in an Electromechanical Flight Control Actuation System

This paper presents a scheme for the detection and isolation of incipient sensor faults in a flight control actuation system. The system considered here is a practical system, which is an electromechanical flight actuator, based on a DC torque motor. The scheme utilizes the analytical redundancy that exists in the system between the linear actuator position, motor shaft velocity and motor current for detection and isolation of the incipient sensor faults. The scheme is based on a single Luenberger observer, which is driven by the motor shaft velocity sensor. Residuals that can indicate various types of faults are generated from the estimate of the sensor output provided by the Luenberger observer. The capability of the residuals, to detect and isolate incipient faults in the sensors, such as bias errors and scale factor errors is demonstrated through simulations. In the event of fault in the position sensor, real time reconfiguration using an estimate of the position from the observer is used for continued operation of the system. The robustness of the fault detection scheme to parameter variations is also examined.