Reconfigurable fault tolerant control against sensor/actuator faults applied to autonomous underwater vehicle dynamics

In this study, a reconfigurable fault-tolerant flight control system against sensor/actuator faults for autonomous underwater vehicles (AUVs) is proposed. First, an approach for detecting and isolating AUV sensor/actuator faults affecting the mean of the Kalman filter (KF) innovation sequence is proposed. Second, an augmented Kalman filter is used to isolate the sensor and actuator faults and estimate the control derivatives corresponding to the faulty actuator. In the case of a sensor fault, the robust Kalman filter algorithm with the filter gain correction is used. With the use of defined variables named as measurement noise scale factor, the faulty measurements are taken into consideration with a small weight and the estimations are corrected without affecting the characteristic of the accurate ones. In case of an actuator fault, fault isolation and identification are performed using the augmented KF. The control reconfiguration procedure is executed by utilizing the identified control distribution matrix. The parameters of the feedback controller are tuned by the control reconfiguration procedure. In the simulations, the steering subsystem dynamics of the AUV model is considered, and the sensor/actuator fault detection and isolation are examined. Some simulation results for the reconfigurable active fault tolerant control against actuator faults are given.