Composite anti-disturbance control for a discrete-time time-varying delay system with actuator failures based on a switching method and a disturbance observer

Composite anti-disturbance control for Markovian jump nonlinear systems via disturbance observer

Based on state feedback control approach and disturbance observer method, a new composite synchronization control strategy is presented in this study for a class of delayed coupling complex dynamical networks with two different types of disturbances. Herein, one of the disturbances is produced by an exogenous system which acts through the input channel, while the other is usual norm-bounded. The main objective of this study is to exactly estimate the disturbance at the input channel, whose output is integrated with the state feedback control law. In this study, the composite control strategy is designed in two forms according to the present and past states’ information about the system. By applying the Lyapunov–Krasovskii stability theory, a new set of sufficient conditions is obtained for the existence of both control strategies separately through the feasible solution of a series of matrix inequalities. The superiority and validity of the developed theoretical results are demonstrated by two numerical examples, wherein it is shown that the proposed control strategy is capable of handling multiple disturbances in the synchronization analysis.

We investigate a robust fault-tolerant control problem for continuous-time Markovian jump systems with an actuator fault and multiple disturbances (one is norm-bounded, whereas the other can be modelled by an exogenous system). Our aim is to construct, simultaneously, a model-dependent disturbance observer for modelling the disturbance estimate and a model-dependent fault diagnosis observer for the time-varying fault estimate and then propose a composite hierarchical control scheme by integrating the fault and disturbance estimates using a state feedback control strategy. Application of the [Formula: see text] control methodology ensures stochastic stability of the resulting composite system with fault compensation, disturbance attenuation and rejection performances. On the basis of Lyapunov stability theory, the existence conditions of the disturbance observer, fault diagnosis observer and composite controller are derived from the solution to a convex optimization problem. Finally, a numerical example is given to illustrate the effectiveness of the proposed techniques.

Composite fault-tolerant control with disturbance observer for stochastic systems with multiple disturbances

This article aims to investigate the security consensus and composite anti-disturbance problems for a class of nonlinear multi-agent systems subjected to stochastic false data injection attacks (FDIAs) and multiple disturbances under a directed communication topology. To attenuate and reject of the negative effects of two types of disturbances, a disturbance observer (DO) is designed to counteract the disturbance produced by exogenous system, and the <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\mathcal {H}_\infty $ </tex-math></inline-formula> control method is adopted to attenuate the bounded errors and variables caused by the other type of disturbances and FDIAs simultaneously. To ensure the consensus performance of MASs, an observer-based control strategy is designed, and a novel adaptive compensation technique is proposed to not only evaluate the upper bounds of the unknown but bounded disturbances but also improve the accuracy of the state observer. Furthermore, a novel event-triggered mechanism (ETM) without requiring continuous communication among neighboring agents is developed to reduce the controller update frequency and the communication burden. Meanwhile, Zeno behavior is excluded. Finally, numerical simulations are provided to verify the availability of the designed method. Note to Practitioners—In multi-agent systems, network security is very important. For example, in smart power grid systems, it is necessary to use the method of state estimation to observe the system to guarantee its safe operation. However, the measured value of the instrument may be affected by FDIAs in the transmission process, thus changing the result of state estimation and causing misjudgment of the system. Similarly, in multi-vehicle systems, FDIAs may destroy the location information of vehicles and cause serious accidents. In addition, the system will be subjected to different types of disturbances in practice, thus reducing the performance of the system. In view of the threat of FDIAs and disturbances to the MAS, a composite anti-disturbance method and an observer-based control strategy are proposed. Meanwhile, to avoid the limitation of communication bandwidth in reality, a novel ETM is developed to save network resources.

Composite anti-disturbance dynamic positioning of vessels with modelling uncertainties and disturbances

Various sources of disturbances exist simultaneously in robotic systems, such as vibrations, frictions, measurement noises, and equivalent disturbances from unmodeled dynamics and nonlinearities. However, most results on anti-disturbance control focus on only one type of disturbances, which cannot reflect the real applications and may lead to design conservativeness due to partial use of the disturbance information. In this paper, we propose a composite hierarchical anti-disturbance control (CHADC) strategy for robotic systems in the presence of multiple disturbances as well as system uncertainties. Particularly, we assume the existence of two types of disturbances, where the first type represents disturbances from exogenous systems with model perturbations, while the second type includes other random disturbances satisfying the L2-norm bound condition. Accordingly, the CHADC control architecture is composed of a nonlinear disturbance observer (NDO) and an H∞ based PID controller, where the NDO is constructed to estimate the first type of disturbances and provide feed forward compensation, while the feedback PID loop is optimized using H∞ theory to minimize the second type of disturbances. Robustness against system uncertainties is also considered in this hierarchical control structure. The proposed control approach is applied to a two-link robotic manipulator and compared with the conventional DOBC (disturbance observer based control) strategies.

This chapter considers anti-disturbance control problem for Markovian jump systems. We propose a composite hierarchical anti-disturbance (CHAD) control methodology, that is, disturbance-observer-based (DOB) control plus \(\mathcal {H}_{\infty }\) control, for the considered systems with nonlinearity and multiple disturbances. The nonlinearity with known and unknown functions is considered, respectively. The multiple disturbances include two kinds: one is supposed to be a norm-bounded vector; the other is described by an exogenous system with perturbations. With the introduction of notion of composite DOB control and \(\mathcal {H}_{\infty }\) control and by choosing a proper stochastic Lyapunov–Krasovskii functional, disturbance observers and special controllers are solved, such that the composite system is stochastically stable, and meets certain performance requirements.

Anti-disturbance observer-based control for fuzzy chaotic semi-Markov jump systems with multiple disturbances and mixed actuator failures

We propose a new composite anti-disturbance control approach with guaranteed input saturation. Such a composite control has two hierarchical loops. The vibrations of flexible appendalges are formulated as one type of disturbances with bounded derivative, for which the disturbance-observer-based controller is designed to compensate in the feed-forward loop. Other disturbances originated from space environment, measurement, actuator and un-modeled dynamics, are merged into the second type of disturbance described by a norm bounded variable. $H$ ∞ state-feedback controller is designed to attenuate the merged disturbance. The input saturation of the actuator is also taken into account in the controller design. The concerned problem is simplfied into a robust control problem via solution of linear matrix inequalities. Numerical simulations and comparisons show that by combining the disturbance observer with $H$ ∞ control, the pointing accuracy of flexible spacecrafts can be improved.

Composite anti-disturbance quantized control for interconnected semi-Markovian systems with multiple disturbances and actuator faults

&lt;p style='text-indent:20px;'&gt;In this paper, the composite anti-disturbances control problem is considered for a class of stochastic systems with multiple disturbances. The states of the system are assumed to be unavailable. A state observer and a disturbance observer are constructed to estimate the states and the matched disturbance respectively. Based on the estimated values of state observer and disturbance observer, a non-fragile composite controller is designed to achieve disturbance attenuation and rejection. By means of the technique of the disturbance compensation control and stochastic control theory, some sufficient conditions are obtained to guarantee that the closed-loop system is asymptotically bounded in mean square or asymptotically stable in probability. Finally, a numerical example is given to verify the validity of the obtained results.&lt;/p&gt;

Composite anti-disturbance control for uncertain Markovian jump systems with actuator saturation based disturbance observer and adaptive neural network

A new anti-disturbance control scheme is proposed for a class of nonlinear systems subjecting to multi-source disturbances in this paper. The uncertain multi-source disturbances are classified into two parts, one is the harmonic or constant disturbance with partial known information, which can be formulated by an exogenous system, another one is unknown time-varying disturbances. The nonlinear disturbance observer(NDO) is constructed separately from the controller design to estimate the first kind of disturbance. By integrating NDO with adaptive backstepping technique, a novel composite anti-disturbance control scheme is proposed for the nonlinear systems. Then the stability analysis of all signals of the closed-loop system is presented. Simulation for a numerical example is given to demonstrate the effectiveness of the results.

A new anti-disturbance control scheme is proposed for a class of nonlinear systems subjected to multi-source disturbances. The uncertain multi-source disturbances are classified into two parts; one is the harmonic and constant disturbance with partial known information, which can be formulated by an exogenous system, and the other consists of unknown time-varying disturbances. The nonlinear disturbance observer (NDO) is constructed to estimate the first kind of disturbance. By integrating the NDO with an adaptive backstepping technique, a novel composite anti-disturbance control scheme is proposed for the nonlinear systems. Then the stability analysis of the closed-loop system is presented. The simulation of a numerical example is given to demonstrate the effectiveness of the proposed results.