A fault detection and isolation (FDI) algorithm is proposed for the stuck fault detection of an aircraft with multiple control surfaces. The proposed FDI approach is composed of an adaptive observer and a bias estimation algorithm. The adaptive observer is designed for the stuck fault detection of the control surfaces, and the bias estimation algorithm is used to estimate the stuck position of the corresponding control surface. The bias estimation algorithm is designed using an unscented Kalman filter. Non-linear back-stepping control is applied. Also, to achieve the fault-tolerant property without redesigning the controller, control allocation technique is used. A non-linear aircraft model with the multiple control surfaces is considered. Numerical simulations are performed to demonstrate the performance of the proposed FDI algorithm.Nomenclature a angle of attack (rad) a 0 trim angle of attack (rad) Da difference between a and a 0 (rad) b sideslip angle (rad) f roll angle (rad) p roll angular rate (rad/s) q pitch angular rate (rad/s) r yaw angular rate (rad/s) g 0 gravitational constant (m/s 2

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To measure the displacement of a shape memory alloy (SMA) coil spring actuator for feedback control, displacement sensors larger than the actuator are normally required. In this study, a novel method for estimating the displacement of an SMA coil spring actuator without a sensor is proposed. Instead of a sensor, coil inductance is used for estimating the displacement. Coil inductance is estimated by measuring the voltage and the transient response of the current. It has a one-to-one relationship with the displacement of the coil and is not affected by load. Previous methods for estimating displacement using resistance measurements are heavily affected by load variations. The experimental results herein show that displacement is estimated with reasonable accuracy under varying loads using coil inductance. This sensorless method of estimating the displacement of an SMA coil spring actuator can be used to build a compact feedback controller because there is no need for a bulky displacement sensor.

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