This article investigates the problem of simultaneous attitude and vibration control of a flexible spacecraft to perform high precision attitude maneuvers and reduce vibrations caused by the flexible panel excitations in the presence of external disturbances, system uncertainties, and actuator faults. Adaptive integral sliding mode control is used in conjunction with an attitude actuator fault iterative learning observer (based on sliding mode) to develop an active fault tolerant algorithm considering rigid-flexible body dynamic interactions. The discontinuous structure of fault-tolerant control led to discontinuous commands in the control signal, resulting in chattering. This issue was resolved by introducing an adaptive rule for the sliding surface. Furthermore, the utilization of the sign function in the iterative learning observer for estimating actuator faults has not only enhanced its robustness to external disturbances through a straightforward design, but has also led to a decrease in computing workload. The strain rate feedback control algorithm has been employed with the use of piezoelectric sensor/actuator patches to minimize residual vibrations caused by rigid-flexible body dynamic interactions and the effect of attitude actuator faults. Lyapunov's law ensures finite-time overall system stability even with fully coupled rigid-flexible nonlinear dynamics. Numerical simulations demonstrate the performance and advantages of the proposed system compared to other conventional approaches.

An analysis of on-line autonomous robust tracking controller based on variable structure control is presented for an aerospace launch vehicle. Decentralized sliding-mode controller is designed to achieve the decoupled asymptotic tracking of guidance commands upon plant uncertainties and external disturbances. Development and application of the controller for an aerospace launch vehicle during atmospheric flight in an experimental setting is presented to illustrate the performance of the control algorithm against wind gust and internal dynamics variations. The proposed sliding mode control is compared to non-linear and time-varying gain scheduled autopilot and its superior performance is illustrated by simulation results. Furthermore, the proposed sliding-mode controller is convenient for implementation.

This paper investigates the problem of finite-time stabilization of a class of uncertain nonlinear systems and a controller is proposed based on combination of integral sliding mode control with finite-time state feedback. The proposed controller consists of two parts. One part rejects matched uncertainties and the other part provides finite time stability. An adaption mechanism is also employed to estimate unknown parameters of the system. The proposed control law guarantees finite-time convergence of the sliding variable in the presence of uncertainties and unknown parameters. By elimination of the reaching phase, in which the system states are quite sensitive to any uncertainties or disturbances, the robustness of the system is guaranteed throughout the entire response. Furthermore, the upper bound of disturbance and uncertainties is not required to be known in advance which makes the suggested controller more flexible in terms of implementation.

This paper proposes an integral sliding mode direct power control (ISM-DPC) strategy for brushless doubly fed induction generators. Two widely applied control strategies are available for this type of generators: hysteresis-based direct power control and vector control. Direct power control suffers from high power ripples and current distortions produced by variable switching frequency. Moreover, the tuning issues of PI controller, which are highly reliant on machine parameters and operating conditions, and necessity of a phase-locked-loop for frame alignment are accounted as limitation of these methods. The proposed integral sliding mode strategy directly controls active and reactive power to provide fast dynamic response and zero steady-state error. This method is developed in the control winding reference frame to avoid the application of PLL. A large-scale brushless doubly fed induction generator (BDFIG) is simulated to validate the effectiveness and robustness of the proposed ISM-DPC method in comparison with widely applied methods, vector control and direct power control.

The rudderless flying-wing UAV design structure poses different challenges in terms of stability, tracking control, and accurate state estimation due to the lack of conventional horizontal and vertical stabilizers. The proposed controller-observer structure in this paper provides proper tracking performance in both longitudinal and lateral modes by augmenting the tracking error integral to the system dynamics for stabilization, and designing the sliding surface as a linear combination of the system states, and further optimizing the sliding surface. By designing the special sliding mode control law in the proposed structure, the robustness against matched and unmatched uncertainties is ensured in the closed-loop system. The robust sliding mode observer, which is an extension of the modified Utkin and Walcot-Zac observer, is used for estimating the system states based on sensor outputs. By this approach, the unknown states of the system are effectively estimated using an appropriate computational algorithm, despite input disturbances and uncertainties. The simulation results confirm the excellent performance of the proposed controller-observer structure in terms of state estimation, stabilization, tracking behavior, and robustness against uncertainties and disturbances

In this paper, a sliding mode predictive control method is proposed for function improvement of affine discrete-time nonlinear systems using integral terminal sliding mode method (ITSMC). The proposed method is based on the integration of terminal integral sliding mode method and model predictive controller which leads to using the advantages of both methods. Indeed, in the proposed method, integral and terminal characteristics of terminal integral sliding mode method are used to design the sliding surface in order to reduce the error (in reaching phase) and to converge to the origin (in sliding phase). Moreover, the chattering phenomenon which usually exists in sliding mode based methods will be decreased using the model predictive controller. The proposed control method has the capability to eliminate the effect of external disturbances and uncertainties. In this paper, it is shown that the model predictive method decreases the chattering phenomenon more than using the saturation function in the control law of the sliding mode method. In addition, using numerical and functional examples, the performance of the proposed method in improving the quality of the system response in the presence of external disturbances and uncertainties is illustrated.