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In this paper, a class of interconnected systems is considered, where the nominal isolated subsystems are fully nonlinear and non-minimum phase. A decentralized Extended Kalman Filter-Extended High Gain Observer (EKF-EHGO) is designed to observe the system states. Then, a systematic backstepping design procedure is employed to develop a novel decentralized robust adaptive output feedback control, in which the adaptive law is designed to counter the effects of the interconnections and uncertainties. The proposed decentralized dynamic output feedback control scheme can guarantee that all the signals in the closed-loop system are uniformly ultimately bounded (UUB). Both interconnections and uncertainties are allowed to be unmatched and bounded by an unknown high-order polynomial, which is a more general form when compared with existing work. Two MATLAB simulation examples are used to demonstrate the effectiveness of the proposed method including a system comprising translational oscillator with rotating actuator (TORA) sub-systems. [ABSTRACT FROM AUTHOR]

A robust adaptive digital controller is systematically investigated on set-point regulation in uncertain systems under input saturation. So, an optimization strategy will be derived to solve the reference regulation robustly in the discrete-time systems. To this purpose, a discrete-time integral controller is considered through a fixed state-feedback structure. Then, its coefficients would be numerically quantified at each sample time by means of a minimization. The formulation and merit of the addressed predictive control method are theoretically proved in the paper. Then the control technique is simulated in a discrete-time equation. Additionally, some numerical results are executed to declare the remarkability and vigor of the recommended algorithm against uncertainties, actuator saturation, and disturbance in contrast to the existing control ways. [ABSTRACT FROM AUTHOR]

This paper is mainly focused on the stabilization problem of uncertain delayed periodic piecewise time-varying systems inclusive of disturbances and faults in actuators. More specifically, the considered system is encompassed of periodic dynamics, which exhibits the nature of switched systems with fixed switching sequence and dwell time. The control protocol is configured in the form of both the present and past state information of the addressed system with passive performance. Moreover, the proposed control approach discloses the stabilization issue mainly by resolving the effect of faults in actuator components. Precisely, the desired periodic gain matrices of the developed controller are calculated by way of solving some matrix inequalities which are derived by making use of Lyapunov stability theory and matrix polynomial approach. As a result, the asymptotic stability of the considered system is ensured in conjunction with satisfied disturbance attenuation index. Conclusively, the simulation results of two numerical examples including mass-spring damping system are presented for validating the theoretical result. [ABSTRACT FROM AUTHOR]

This paper addresses a novel robust gain-scheduling(GS) state-feedback (SF) H ∞ (induced L 2) control method for uncertain continuous-time(CT) systems having actuators with hard rate and magnitude bounds. The proposed method relies on acceleration form representation of the uncertain CT system. The technique enables the user to represent the control signal and its slew rate as auxiliary outputs along with the main controlled output. Two different norms, namely the induced L ∞ and L 2 are used to control the system effectively. While the L ∞ gain from the exogenous disturbance inputs to the control signal related outputs is used to deal with actuator saturation problem, L 2 gain from the disturbance inputs to the performance outputs is utilised in attenuation of the effects of the disturbances. To achieve these goals with minimal conservatism, we develop new forms of dilated Matrix Inequality (MI) conditions for peak-to-peak gain and L 2 gain with no additional conservatism. Then, we propose a novel robust GS control methodology to deal with the problem via dilated MIs and a modified full block S-procedure method (MFBSPM). The utilisation of MFBSPM ensures that the robust control design method of this note applies to any uncertain system having rational parameter dependence. Finally, the efficiency of the presented method is portrayed through extensive simulations of the responses of a marine vessel to wave excitations in which the vessel model is assumed to have magnitude and rate limited active fin stabiliser. [ABSTRACT FROM AUTHOR]

This paper studied an adaptive actuator fault-tolerant control scheme for the flexible Euler–Bernoulli beam in the three-dimensional space with output constraints and uncertain end load. The dynamic models are represented by partial differential equations (PDEs) and ordinary differential equations (ODEs). When part of the actuator fails, an adaptive control scheme is designed to regulate the vibration and stabilize the flexible three-dimensional Euler–Bernoulli beam. Barrier Lyapunov Function (BLF) is adopted to realize output constraints of the system. Adaptive control law with projection mapping operator is designed to compensate for the end load which is uncertain and bounded. The goal of this paper is to suppress the displacement of the flexible three-dimensional Euler–Bernoulli beam which can be constrained in given bounds under actuator fault and uncertain, bounded end load. It is confirmed that the proposed control scheme can deal with the vibration, adaptive actuator fault-tolerant control, uncertain and bounded end load and output constraints of the system simultaneously. Finally, numerical simulations illustrate the effectiveness and feasibility of the method. [ABSTRACT FROM AUTHOR]

In this paper, we aim at addressing the problem of robust quantized control for singular system with time delay, actuator saturation and nonlinear perturbations. Based on Lyapunov Krasovskii approach, a novel delay-dependent sufficient condition is given to guarantee the corresponding system is admissible in terms of Linear Matrix Inequalities (LMIs). The submitted results are derived by exploiting three integral inequalities. A robust quantized controller are further developed as well as the domain of attraction. Finally, examples are utilized to demonstrate the merit of the proposed results. [ABSTRACT FROM AUTHOR]

This paper studies the problem of composite control for a class of uncertain Markovian jump systems (MJSs) with partial known transition rates, multiple disturbances and actuator saturation. Compared with the existing results, a novel robust composite control scheme is put forward by virtue of adaptive neural network technique. For MJSs, the partial unknown information on transition rates and the actuator saturation influence the design of disturbance observer and the robust H ∞ controller. Firstly, without taking account of external disturbances, the network reconstruction error and saturation, a novel robust adaptive control strategy is established to ensure that all the signals of the closed-loop system are asymptotically bounded in mean square. Secondly, the solvability condition for ensuring the robust H ∞ performance is given by using a modified adaptive law, where the saturation is treated as a disturbance-like signal. Finally, the simulations for a numerical example and an application example are performed to validate the effectiveness of the proposed results. [ABSTRACT FROM AUTHOR]

• Partial state constraints and actuator faults are simultaneously addressed in integrated guidance and control. • The barrier Lyapunov function and modified saturation function are employed to prevent the attack angle, sideslip angle and velocity deflection angle from violating the constraints. • An auxiliary system is constructed to remove the adverse effects that caused by the modified saturation function. The adaptive laws are constructed to deal with actuator faults and uncertainties in the IGC system. • It is theoretical shown that all signals in closed-loop system are bounded while the state constraints are not violated in presence of actuator faults. In this paper, a novel adaptive integrated guidance and control (IGC) scheme is proposed for skid-to-turn (STT) missile with partial state constraints and actuator faults. Considering the strict-feedback form of the IGC model, the dynamic surface control (DSC) approach is adopted to design the IGC scheme. To prevent the attack angle, sideslip angle and velocity deflection angle from violating the constraints, the barrier Lyapunov function (BLF) and modified saturation function are employed in the IGC design procedure. Moreover, an auxiliary system is constructed to remove the adverse effects that caused by the modified saturation function. The adaptive laws are constructed to estimate the actuation effectiveness of actuators and the upper bounds of lumped uncertainties in the IGC model. It is theoretically shown that all signals in the closed-loop system are bounded while the state constraints are not violated in presence of actuator faults and uncertainties. Numerical simulation results are presented to verify the effectiveness and robustness of the proposed IGC scheme. [ABSTRACT FROM AUTHOR]

This paper is concerned with the problem of robust fault-tolerant H ∞ dynamic output feedback control for fractional-order linear uncertain systems with the order satisfying 0 < α < 1 in the presence of actuator faults. A new linear matrix inequality (LMI) formulation corresponding to the H ∞ norm of fractional-order linear systems is proposed. Based on the new formulation and by introducing a new linearizing change of variables, sufficient conditions for robust fault-tolerant H ∞ dynamic output feedback controller designs are derived in term of LMIs. Furthermore, the proposed controller not only enables the system to keep robust stabilization, but also achieves a better H ∞ performance compared with the existing methods. Numerical examples are given to illustrate the design procedure and its effectiveness. [ABSTRACT FROM AUTHOR]

Highlights • An adaptive robust control method is proposed for a novel electromagnetic valve actuator. • Uncertainties such as combustion force variations and parameters variations can be restrained. • An anti-windup compensation strategy is proposed to solve the current saturations. • Simulational and experimental results demonstrate the effectiveness of proposed method. Abstract Electromagnetic valve actuators (EMVA) can achieve independent fully flexible control of valve and thus reduce the fuel consumption significantly. In order to improve the performance of the engine, precise motion control of EMVA is requird. Most of the researches published so far focus on the compensations of nonlinearities such as frictions and parameters variations. However, the influence of the varying combustion force on the exhaust valve needs to be considered. An adaptive robust control (ARC) method was developed in this paper to compensate the major nonlinearities, including parameters variations and combustion force variations. The parameters of EMVA system were tuned online via certain adaptation law. Combustion force variations were compensated by robust control law. In addition, current saturation was caused by large combustion force, which was then solved by proposing an anti-windup compensation strategy. The effectiveness of the proposed ARC method was verified by simulations and experiments, and the results show that ARC method can adapt to parameters variations and large changes in combustion force. [ABSTRACT FROM AUTHOR]

This paper studies the robust fault tolerant control problem of distributed network control systems (DNCSs). DNCSs are defined as the networked control systems (NCSs) consist of several sub-systems. Each sub-system contains its own sensor, controller and actuator. This kind of systems widely exist in the real world, such as the urban water supply network, smart grid and so on. Three main aspects of DNSCs are investigated in this paper. Firstly, we consider the variable structure problem of DNCSs. Meanwhile, the network problems including time delays, packet-dropouts and quantization errors are considered. Finally, the actuator fault tolerant control problem due to the possible poor working environment is also studied. A series of two-mode-dependent controllers are proposed to stabilize such DNCSs and meet the robust closed-loop performance. By using the Lyapunov–Krasovskii (L-K) function, sufficient conditions on the existence of such controllers are presented in terms of bilinear matrix inequalities (BMIs). A cone complementarity linearization (CCL) algorithm is given to solve proposed BMIs. Finally, a simulation example is exploited to show the effectiveness of the proposed method. [ABSTRACT FROM AUTHOR]

This paper addresses the problems of state/fault estimation (FE) and fault tolerant control (FTC) for a class of Takagi–Sugeno (T–S) fuzzy systems subject to simultaneously external disturbances, sensor and actuator faults. A fuzzy-reduced-order robust state/fault estimation observer is proposed in this paper. The observer can not only estimate system state, sensor and actuator faults simultaneously, but also attenuate the influence of disturbances. Compared with the existing results, the observer has a wider application range and a lower dimension. Using the information of estimation, an observer-based fault tolerant controller is designed to compensate the fault effect and guarantee the stability of closed-loop system. In the paper, the observer and the controller are designed separately, which can avoid the coupling between them. As a result, the gain matrices of the observer and the controller can be calculated separately. At last, the simulations show the effectiveness of the proposed method. [ABSTRACT FROM AUTHOR]

Voice coil actuators (VCAs) are widely used for motion control applications that require high precision and fast acceleration. However, they have one disadvantage of short travel ranges typically on the order of centimeters. To overcome this disadvantage, this paper employs an existing concept called dual-stage actuation and combines a linear VCA with a low-cost dc-motor (DCM) to construct a linear dual-stage actuation (DSA) positioning system, which extends the travel range as large as that provided by the DCM while retaining the positioning accuracy offered by the VCA. For this setup, proper controllers are crucial to achieve the desired performance. Hence, we first identify the DSA model and investigate the interaction force between the VCA and DCM stage. Next, robust controllers are specifically designed for the DCM and VCA stage, respectively. Finally, experiments are carried out to verify the robust tracking performance of the developed linear DSA positioning system. It is demonstrated that the developed DSA positioning system offered a cost-effective solution to extending the working range of the existing VCA whilst retaining the positioning accuracy. [ABSTRACT FROM AUTHOR]

This paper considers the problem of robust finite-time non-fragile memory H ∞ control for discrete-time singular Markovian jumping systems with actuator saturation. By using the multiple Lyapunov function approach and the linear matrix inequalities (LMIs) techniques, novel sufficient conditions are obtained that ensure the systems singular stochastic finite-time bounded and singular stochastic finite-time H ∞ bounded are obtained. Then the non-fragile memory feedback controllers are designed and the results are extended to LMI convex optimization problems to get the optimal values of attenuation level and the estimation of saturation attraction domain. Finally, some numerical examples are provided to illustrate the viability and effectiveness of the proposed methods. [ABSTRACT FROM AUTHOR]

In this paper, the problem of robust H ∞ control for uncertain singular discrete T–S fuzzy time-delay systems with actuator saturation is addressed. Based on singular value decomposition approach, a delay-dependent sufficient condition for the H ∞ control problem is obtained by constructing multiple Lyapunov–Krasovskii function and a latest difference inequality. Meanwhile, a parallel-distributed compensation (PDC) state feedback H ∞ controller design problem is solved by linear matrices inequalities (LMIs) to guarantee the closed-loop system not only is admissible but also possesses H ∞ performance index γ . Moreover, the problem of estimating the domain of attraction for the discrete T–S fuzzy closed-loop system is formulated and solved as a LMI optimization problem. Finally, numerical examples demonstrate the obtained estimation of the domain of attraction and H ∞ performance index γ less conservative than some result reported in the literature. [ABSTRACT FROM AUTHOR]

This paper investigates the distributed cooperative controller design problem for multi-agent systems in the presence of actuator faults. Both the partial loss of actuator effectiveness and the actuator bias faults are considered. A constructive design method is presented to achieve the synchronization and/or tracking control of multi-agent systems. The control protocol for each agent consists of three modules: the actuator fault detection module, the nominal control module, and the auxiliary control module. The auxiliary control module is activated as soon as the actuator faults are detected. The control protocols are locally distributed in the sense that the control modules designed for each agent only require the information of itself and its neighbors. The loss of symmetry in the digraph Laplacian matrix is also considered. The analysis is suitable for the multi-agent systems with a general directed communication graph. The proposed fault-tolerant control schemes are applied in the formation control of multi-robot systems. Numerical simulation results are presented to show the effectiveness of the proposed control methods. [ABSTRACT FROM AUTHOR]

This paper investigates the problem of robust output feedback control of uncertain continuous-time time-delay systems with both external disturbances and saturating actuators. Both the system uncertainties and the external disturbances are assumed to be time-varying and bounded, and the states of the system under consideration are not available but detectable. First, in the absence of external disturbances, some delay-dependent conditions for designing observer-based output feedback controller are derived which ensure that the system without perturbations on its input matrices can be stabilized together with the domain of attraction. To obtain a maximal estimate of the domain of attraction, an iterative optimization algorithm is proposed. When the system input matrices are subject to perturbations, new stabilization conditions are obtained to adjust the gain of the observer on the basis of the above-mentioned controller design rules. Second, in the presence of external disturbances, the robust observer-based output feedback controller is designed to guarantee that the corresponding closed-loop system converges uniformly exponentially to a ball with an initial admissible domain. Finally, numerical results are given to demonstrate the effectiveness of the proposed method. [ABSTRACT FROM AUTHOR]