Diagnosis of Incipient Sensor Faults in a Flight Control Actuation System

This paper presents a scheme for fault diagnosis in a flight control actuation system. The electromechanical control actuator considered here is based on a DC torque motor. The scheme utilizes the analytical redundancy that exists in the system between the linear actuator position, motor shaft angular velocity and motor current for diagnosis of incipient sensor faults in the system. Fault diagnosis is done using a single Kalman filter, which is driven by the motor shaft velocity sensor. Diagnosis of bias and scale factor faults in the position and current sensor is carried out using structured residuals that are generated using the Kalman filter estimates. Bias and scale factor errors in the velocity sensor are detected using the statistical properties of the innovation sequence of the Kalman filter. In the event of fault in the position sensor, real time reconfiguration using an estimate of the position from the Kalman filter is used for continued operation of the system. Robustness of the scheme to parameter variations is also examined