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A complex dynamical network (CDN) can be considered as the composition system with the nodes subsystem (NS) and the links subsystem (LS), and both subsystems are coupled with each other. In this paper, two vector differential equations (VDE) are used to describe the dynamical behaviours of NS and LS, respectively, in which the dynamical behaviour of NS is considered as the VDE with the second derivative term (SDT). This paper mainly focuses on the dynamics of LS, which is represented as VDE with the intuitive topologic feature of outgoing links, and investigates the design of the tracking controller for NS and the auxiliary tracking objectives (ATO) for LS. Firstly, the dynamical models of NS and LS in CDN are proposed, and the corresponding assumptions are given. Secondly, based on Lyapunov stability theory, the controller of NS and the ATO of LS are designed so that the state of NS can asymptotically track the given reference signal. Finally, the effectiveness of the proposed control strategy in this paper is verified by the numerical simulation example with N two-links robots. Abbreviations: ATO: auxiliary tracking objectives; CDN: complex dynamical network; LS: links subsystem; MDE: matrix differential equation; NS: nodes subsystem; SDT:second derivative term; VDE: vector differential equation; [ABSTRACT FROM AUTHOR]

To solve the control problem of time-varying state-scale nonlinear systems whose initial state is not affected by settling time, fixed-time convergence algorithms are proposed for first-order systems and higher-order systems in this paper. First, a scalar model is used to illustrate how the time-varying feedback parameter can guarantee that the system achieves asymptotic stability while achieving finite-time convergence, and it is proved that the settling time obtained in this paper is only related to the prescribed boundary. This allows us to design the settling time with an appropriate parameter based on the prescribed boundary. To exhibit the effectiveness and extensibility of the proposed algorithm for first-order scalar systems, the results are subsequently extended to general higher-order systems based on the backstepping method. By introducing numerical simulation results, this paper verifies that the proposed algorithm will make the system achieve asymptotic stability and its output can converge to a given boundary, regardless of the system's initial states. [ABSTRACT FROM AUTHOR]

In this paper, we investigate various stabilisation problems of a hybrid system of elasticity, consisting of a thin tape, which moves axially between two sets of rollers. We present a control solution, which works simultaneously, for three variants of the tape model. In particular, we design boundary feedback control laws via Lyapunov's second method. The resulting closed-loop system for the general case is then analysed, where we prove the existence and uniqueness of solution using the semigroup theory of linear operators; furthermore, we prove the exponential decay of the solution via a frequency domain theorem. The stabilisation of the two other special cases is derived implicitly from the general case proofs presented in the paper. Finally, the paper is concluded by presenting computer simulations to support the theoretical results. [ABSTRACT FROM AUTHOR]

Transient performance is a highly valued factor in real control systems. Having a suitable transient performance not only guarantees the safety of the system but also makes the response more desirable by reducing transient factors like the overshoot and the settling time. This paper is the first attempt to design a novel controller to improve the transient performance of switched singular time-delay systems. The proposed controller comprises a combination of linear and nonlinear parts. First, a linear part is designed to fulfill the stabilisation. Then a nonlinear part is added to it to improve the transient response. The admissibility of the closed-loop system is investigated through some given theorems based on the Lyapunov-Krasovskii approach. The closed-loop system's regularity and impulse freeness are also guaranteed in the given theorems. Computer simulation of some numerical and practical examples will endorse the theoretical achievements afterward. [ABSTRACT FROM AUTHOR]

This paper investigates the finite-time time-varying formation-containment control problem for satellite formation flying under discontinuous control protocols based on nonsmooth analysis. The desired consequence is that the follower satellites can converge into a dynamic convex hull in finite time, which is spanned by leader satellites' time-varying formation according to the reference signal. Firstly, to accomplish this objective, a finite-time time-varying formation-containment control strategy is proposed for satellite formation system in present of the bounded disturbances and satellites' accelerations, which are known for each satellite. Then, considering the case that the information of disturbances may not be measured accurately and the accelerations of satellites may not be obtained globally in some practice application scenarios, a fully distributed adaptive control strategy is proposed by introducing the dynamic variables. The adaptive variables can compensate the unknown items and adjust with the evolution of neighbour satellites' states, which makes the controller more flexible. Moreover, the proposed control strategies are able to guarantee a fast dynamic response and also a suppression of disturbance. Finally, the performances of the proposed strategies are demonstrated by numerical simulations. [ABSTRACT FROM AUTHOR]

This paper investigates the secure state estimation problem of the cyber-physical systems (CPSs) in the presence of malicious attacks. Considering the destructiveness and stealthiness of the attacker, a novel stochastic transmission scheme, in which the repeater generates transmission data by randomly combining some measurement values, is proposed to ensure the effectiveness of the attack detector. A filter equipped with the $ \chi ^2 $ χ 2 detector and the stochastic transmission scheme is proposed to conduct the secure state estimation. The attack probability condition of the estimation error being mean-square bounded is given, which indicates that stochastic transmission scheme has a limited effect on the filter. Some numerical simulations are given to illustrate the effectiveness of the proposed transmission scheme. [ABSTRACT FROM AUTHOR]

This paper mainly investigates the problem of the exponential synchronisation for delayed neutral-type multi-weights complex networks (DNMCNs) with regime-switching jump diffusion under aperiodically intermittent control. Compared with the related works, hybrid time delays and regime-switching jump diffusion are introduced into neutral-type networks which can better simulate more complicated practical applications. The introduction of regime-switching jump diffusion increases the difficulties of synchronisation analysis in comparison with the Markovian jump diffusion. Meanwhile, it is noteworthy that we firstly extend the availability of aperiodically intermittent control scheme to handle the synchronisation issue with DNMCNs. On the basis of a technique that combines the Lyapunov method and graph theory, some sufficient criteria to synchronise DNMCNs via intermittent control are obtained. Finally, an oscillator system is considered as the application, and the corresponding numerical simulations are proposed to validate the applicability of the obtained theorems and show the effectiveness. [ABSTRACT FROM AUTHOR]

In this paper, we deal with the problem of stabilisation for a class of distributed semilinear systems. The considered systems present a state time delay and evolve in Banach spaces. A new stabilising feedback control is proposed. Two kinds of stabilizability, namely exponential and weak stabilizability, are investigated. An explicit estimate of the energy decay rate is given. Some illustrating applications to parabolic and hyperbolic equations with numerical simulations are considered. [ABSTRACT FROM AUTHOR]

In this paper, we derive the necessary conditions for time-energy optimal control of input-affine nonlinear systems using Hamilton–Jacobi–Bellman equation. The objective function is chosen as a weighted combination of control effort and time-horizon minimisation. The necessary conditions of optimality are transformed such that the resultant conditions are structurally similar to a differential matrix Riccati equation. A closed-form approximate solution to these necessary conditions is derived such that the resulting closed-loop dynamics is locally exponentially stable around the origin. Furthermore, it is also shown that the states converge within a ball of an arbitrarily small radius around the origin within a finite time. Finally, the performance of the proposed controller is tested using numerical simulations for Vander Pol's oscillator as well as spacecraft detumbling problem. Furthermore, the performance of the proposed controller is also tested in comparison to the infinite-horizon state-dependent Riccati equation controller. [ABSTRACT FROM AUTHOR]

This paper aims to address robot/environment interacting problems by designing an adaptive finite-time impedance controller. To deal with crucial issues regarding these sorts of problems, namely interacting with unknown environments and the system's uncertain nonlinearity, a backstepping control structure accompanied by an adaptive Taylor series system is developed. By designing a sliding surface term, two new variables are defined to form the backstepping controller to guarantee that the sliding surface converges to zero in a finite time. Also, impedance parameters are tuned adaptively using the gradient-descent algorithm inspired by a well-designed control literature. The designed controller has several useful features, such as being capable of implementing on n-DOF (degree-of-freedom) industrial manipulators, a guaranteed finite-time stability analysis, a regressor-free design, and dealing with uncertainties. Finally, a numerical simulation applied on a six-DOF manipulator and also a comparison with an impedance control are provided to show the efficiency of the designed controller. [ABSTRACT FROM AUTHOR]

This paper designs event-triggered delay compensation and disturbance attenuation control algorithms for multi-agent systems. First, through predictor-based model reduction method, an unknown large input delay can be compensated and delay-free dynamics is obtained. Based on the transformed systems, predictive descriptor observers are proposed to obtain estimated system states and sensor faults. Then, an event-triggered fault-tolerant algorithm is designed to save energy resources for communication among the agents while attenuating the disturbances. Moreover, it is validated that the systems do not exhibit Zeno behaviour using the designed event-triggering sequence. Numerical simulations are conducted to demonstrate the effectiveness of designed algorithms. [ABSTRACT FROM AUTHOR]

In this paper, the active disturbance rejection control approach is addressed for a class of lower triangular uncertain stochastic nonlinear systems driven by coloured noises. An extended state observer is first constructed to estimate the stochastic total disturbance including the total effects of internal uncertainties and external disturbances affecting system performance, and then an active disturbance rejection controller based on estimation and compensation is designed to obtain desired closed-loop performance. It is shown with a rigorous analysis that the closed-loop state tracks a reference trajectory generated from the target system in practically mean square and almost sure sense. Some numerical simulations are performed to validate the practicality of the proposed control strategy. [ABSTRACT FROM AUTHOR]

This paper is concerned with the stochastic model predictive control problem (SMPC) for a class of networked control systems with exogenous disturbances and restrictions on communication frequency. A self-triggered SMPC algorithm with an improved triggering condition is designed which integrates the co-design of both the current control inputs and the maximum sampling interval, with the aim of reducing the amounts of communication transmission while guaranteeing the specific performance. To give consideration to both probabilistic guarantee and computability, chance constraints on both states and inputs are transformed into deterministic ones by leveraging Cantelli's inequality and linearisation techniques, so as to be solvable for the optimisation problem. Meanwhile, the nonconvex terms in dynamics of covariance propagation are averted through introducing the covariance upper bound control approach. The formulated online optimisation problem is convex to all decision variables. The theoretical analysis on recursive feasibility and closed-loop stability is addressed for the proposed self-triggered SMPC scheme. Finally, the efficacy and achievable performance of the proposed algorithm are showcased through numerical simulations. [ABSTRACT FROM AUTHOR]

In this paper, we investigate the impulsive synchronisation of linear complex dynamical networks (CDNs) with time delay on time scales by a method of pinning impulsive control. We use the time scales theory and the Lyapunov method to derive a synchronisation criterion. We find that we can achieve the synchronisation of CDNs through only controlling a small number of nodes and the modelling framework here can enrich the models of continuous/discrete-time CDNs. In the end, we give some numerical simulations to demonstrate the feasibility of the theoretical analysis. [ABSTRACT FROM AUTHOR]

In this paper, we focus on a patch-structured Nicholson's blowflies system incorporating mature delay and feedback delay. First, by exploiting the differential inequality technique, fluctuation lemma and Brouwer fixed point theorem, we obtain the persistence and existence of the positive equilibrium point with different components. Second, we develop an approach to establish some new criteria to guarantee the local stability and global attractivity of the positive equilibrium point vector, which complement and improve some existing results. Last, the effectiveness and feasibility of the theoretical results are illustrated by some computer simulations. [ABSTRACT FROM AUTHOR]

This paper investigates the security issue of the data replay attacks on control systems with the LQG controller. The attacker tries to store measurements and replay them in further times. The main novelty in this paper is stated as proposing a different attack detection criterion under the existence of a packet-dropout feature in the network by using the Kullback-Leibler divergence method to cover more general problems and with higher-order dynamics. Formulations and numerical simulations prove the effectiveness of the newly proposed attack detection procedure. Unlike previous approaches that the trade-off between attack detection delay or LQG the performance was significant, in this approach it is proved that the difference in this trade-off is not considered in early moments when the attack happens since the attack detection rate is rapid and thus, the attacks can be stopped with defense strategies in the first moments with the proposed attack detection criterion. [ABSTRACT FROM AUTHOR]

A fixed-time bipartite flocking protocol was proposed in a paper titled by 'note on the fixed-time bipartite flocking for nonlinear multi-agent systems'. Although effective and comprehensive, there exists irrigorousness in derivation for the protocol. In this paper, we aim at improving the derivation of protocol proof to ensure fixed-time bipartite flocking is achieved. Moreover, it is also found that it is irrigorous in terms of choice of protocol parameters in Xiao et al. [(2020). A note on the fixed-time bipartite flocking for nonlinear multi-agent systems. Applied Mathematics Letters, 99, 105973]. To overcome the shortcomings, an alternative control protocol is presented to solve fixed-time bipartite flocking problem of multi-agent systems in this paper. Finally, by numerical simulation, we illustrate that the choice of power parameter should be improved at some extent, also the validity of the alternative protocol is verified by numerical simulation. [ABSTRACT FROM AUTHOR]

The paper presents the results of experimental validation of the Newton observer for estimation of the magnetic flux within the feedback control of a nonlinear active magnetic bearing (AMB) system. In the preliminary work the Newton observer was adapted for the exact discrete-time model of the simplified one-degree-of-freedom AMB system, operated with zero-bias flux and under the voltage switching strategy, and showed good results in case of numerical simulations. The objective of this paper is to confirm these results on the basis of experimentation. The experiments were conducted on the AMB test rig, developed and manufactured at Bialystok University of Technology. [ABSTRACT FROM AUTHOR]

This paper proposes a new hybrid robust control method for control of an autonomous underwater vehicle. Fractional sliding mode control (FSMC) is robust against external disturbances. The main drawback of the FSMC method is creating a chattering phenomenon. Therefore, a compound control method is applied, which benefits in both robustness of the FSMC method and chattering elimination by the new control algorithm. A random noise is applied in order to verify the robustness of the proposed control method. The stability of FSMC and proposed compound control method has been verified by Lyapunov theory. The effectiveness of the proposed control method is compared with FSMC, which numerical simulation results confirm the best performance of the proposed control method. [ABSTRACT FROM AUTHOR]

This paper is concerned with the design of a robust finite-time observer for a class of uncertain nonlinear systems. The novelty of the proposed approach lies in estimating uncertainties accurately in a finite time as well as states at the same time, without any constraint on the structure of the matrices of the system. In the proposed method, in contrast to similar papers, considering the system in canonical form or triangular structure is not necessary. In this paper, sufficient conditions are given to guarantee the exact estimation of both state variables of the system and uncertainties in a finite time. Finally, the performance and robustness of the proposed observer are validated using a numerical simulation. [ABSTRACT FROM AUTHOR]

This paper intends a Euler-Lagrange passivity-based controller (EL-PBC) for the three-level (TL) Ćuk PFC converter for EVs battery charging application. The TL Ćuk converter has features of reduced filter size and voltage stress of switches. First, the Euler-Lagrange formulation is used to develop the mathematical modelling. Then, the EL-PBC methodology is implemented by injecting a virtual resistor in series with the input inductor. Further, the stability analysis is also carried out. To improve the performances against input perturbations and reduce the steady state error, a PI controller is integrated with the aforesaid controller and its performances are investigated. Furthermore, the power quality of the charger is assessed and it satisfies IEC 61000-3-2 Class C standard. This controller is also compared with the benchmark PI controller. A prototype model of same specifications is tested in hardware in loop. Computer simulations and test results are presented to validate the theoretical aspects. [ABSTRACT FROM AUTHOR]

This paper deals with the problem of feedback stabilisation of bilinear systems with discrete delay in a Hilbert space. We consider the decomposition of the phase space and we propose a bounded feedback control to study the weak, strong and exponential stabilisation. Firstly, we discuss the well possedness of mild solutions of the considered systems. Secondly, some sufficient conditions are given to guarantee the feedback stabilisation for the bilinear systems. The stabilisation results are given in term of observation estimates. Furthermore, an explicit decay estimate of the stabilised state is obtained in the strong stabilisation case. At the end, examples with numerical simulations are given to show the applicability of our theoretical results. [ABSTRACT FROM AUTHOR]

In this paper, we examine the application of the well-known hysteresis switching algorithm of adaptive control in the case of a continuously parameterised set of candidate controllers. Subject to existence of a feasible controller in the set, we prove that if the performance functions used at each time by the hysteresis algorithm are selected to be uniformly positive definite in the controller parameters, then one may safely set the hysteresis constant to zero without inducing chattering instability, and ensuring convergence to a performance-optimising controller. Expanding preliminary version of our work that we presented at the 2011 American Control Conference, the present paper adds new numerical simulation examples to demonstrate the application and benefit of the theory. [ABSTRACT FROM AUTHOR]

This paper employs the observer-based output feedback control technique to deal with the problem of spatiotemporally asynchronous sampled-data control for a linear parabolic PDE on a hypercube. By the spatiotemporally asynchronous sampled-data observation outputs, an observer-based output feedback control law is constructed, where the sampling interval in time is bounded. By constructing an appropriate Lyapunov–Krasovskii functional candidate and applying a weighted Poincaré–Wirtinger inequality on a hypercube, it is shown under a sufficient condition presented in terms of standard linear matrix inequalities that the suggested spatiotemporally asynchronous sampled-data control law asymptotically stabilises the PDE in the spatial H 1 (Ω) norm but its convergence speed can be regulated by a known constant. Moreover, both open-loop and closed-loop well-posedness analysis are done within the framework of C 0 semi-group. Finally, numerical simulation results are presented to support the proposed design method. [ABSTRACT FROM AUTHOR]

This paper is concerned with prescribed-time functional unknown input observer (PTFUIO) design for linear descriptor systems. First, by constructing two identical asymptotic convergence functional observers, a new PTFUIO is developed which can achieve an exact estimation within an arbitrarily prescribed time, where both the estimation accuracy and the convergence time pre-definition are independent of the initial conditions of the original system. Also, the necessary and sufficient conditions for the existence of such the PTFUIO are given in terms of the original system matrices which are easy to examine. Finally, numerical simulations are given to illustrate the effectiveness of the proposed method. [ABSTRACT FROM AUTHOR]

In this paper, a self-tuning Robust Integral of Sign of Error (RISE)-based backstepping controller is designed for an electro-hydraulic arm system with a fourth-order system model. The RISE controller, which constitutes the robust part of the control rule, is fused with a backstepping control strategy to cope with model-based and parametric uncertainties. Different from a classical RISE control rule, a tanh ⁡ (⋅) function is used instead of a sgn (⋅) function to obtain a more smooth control signal. All the gains in the RISE controller are tuned by using continuous update rules. The efficiency of the controller is demonstrated by conducting numerical simulations. [ABSTRACT FROM AUTHOR]

This paper investigates the finite-time multi-target tracking problem of networked Euler–Lagrange systems (NELSs) with a directed interaction topology, parametric uncertainties and external disturbances. A novel finite-time hierarchical active disturbance rejection control (ADRC) algorithm is designed to handle such a challenging problem without velocity measurement. To be specific, a nonsingular distributed estimator algorithm is newly designed to respectively estimate the states of the targets in a finite time. Based on the extended state observer (ESO), we present a finite-time local control scheme to obtain satisfactory tracking performance of the NELSs. Besides, sufficient conditions for deriving the finite-time stability of the cascade closed-loop systems are presented based on the Lyapunov argument. Finally, numerical simulations are performed to show the control performance and feasibility of the main results. [ABSTRACT FROM AUTHOR]

In this paper, a model for a multi-agent swarm evolving in a d-dimensional space is proposed. The model consists of a balance among attraction to a given goal and attraction/repulsion among agents. One of the main characteristics of the model is the presence of an interaction matrix on agents' coordinates, defining some properties of the swarm formation. The paper focuses on the analysis of the new model highlighting the agents' steady-state behaviour both in terms of static and rotating configuration around the goal. Numerical simulations are provided to support the obtained results. [ABSTRACT FROM AUTHOR]

Finding feasible solutions to motion planning and control problem of robotic systems in different environments with various applications is an active area of research. This article presents a new solution to the motion planning and control problem of a three-dimensional articulated mobile manipulator comprising a car-like mobile platform and a three-dimensional n-link articulated arm using the Lyapunov-based control scheme. The motion of the system is described as twofold: first, the car-like mobile platform moves from an initial position to its pseudo-target, and second, when the mobile platform is within some predefined distance from the pseudo-target, the end-effector of the robot arm is attracted to its designated target. Therefore, presenting a new 2-Step Algorithm in this paper for dual movement of the articulated mobile manipulator in 3D. In addition, a workspace cluttered with fixed spherical and rod obstacles of random sizes and positions is considered in this research. For the mobile manipulator to avoid an obstacle, the Minimum Distance Technique is adapted where a point on the robot that is closest to an obstacle will avoid the obstacle. The convergence of the two bodies and the stability of the mechanical system are guaranteed by the Lyapunov's direct method. The continuous nonlinear control laws proposed from the control scheme also take into account all mechanical singularities and velocity limitations associated with the system. Theoretical proofs and computer simulations validate the new continuous, acceleration-based, nonlinear, time-invariant control laws. [ABSTRACT FROM AUTHOR]

Dealing with the flocking problems of Cucker-Smale systems is a challenging issue. In this paper, the finitetime and fixed-time flocking problems of the Cucker-Smale system are investigated. By designing new continuous non-Lipschitz pinning controllers and using the theory of differential equations, sufficient conditions for the flocking of Cucker-Smale systems are obtained. Besides, sufficient conditions are given to ensure that there is no collision during the process of flocking. The effect of control parameters on the convergence speed is also investigated. The results show that the convergence time is related to control parameters and the density of pinned nodes. Finally, some numerical simulations are used to verify the theoretical results. [ABSTRACT FROM AUTHOR]

In this paper, the cooperative global output consensus problem is studied for a class of nonlinear multi-agent systems with a directed communication topology, where each agent has different nonlinear dynamics. A novel event-triggered control protocol with a dynamic compensator is proposed. By using Lyapunov theory, it is proved that the output tracking errors exponentially converge to zero under the event-triggered control protocol. At the same time, the states of all agents are not triggered synchronously, that is, whether each agent triggers or not only depends on its own state information. Moreover, with the unified frame work of the distributed event-triggered strategy, all the inter-event times are lower-bounded by a positive constant and the Zeno behaviour is excluded. Finally, some numerical simulation examples are given to illustrate the advantages of the proposed event-triggered consensus protocol. [ABSTRACT FROM AUTHOR]

Multiplexed model predictive control (MMPC) is a recently proposed efficient model predictive control (MPC) algorithm, which can effectively reduce the computational burden of the online optimisation in MPC implementation by updating the control inputs in an asynchronous manner. This paper investigates the application of MMPC in active vehicle suspension design. An MMPC controller integrated with soft constraints and a Kalman filter is proposed based on a full-car model. Ride comfort, roadholding and suspension deflection are considered in this paper, where ride comfort and roadholding are formulated as a quadratic cost function in terms of sprung mass accelerations and tyre deflections, while suspension deflection performance is formulated as a hard constraint. The saturation of the actuator force is also considered and formulated as a hard constraint as well. Numerical simulation is performed with respect to different choices of weighting factors, vehicle speeds and control horizons. The results show that the overall performance of ride comfort and roadholding can be improved significantly by employing MMPC and the average time taken by MMPC to solve the individual quadratic programming problem is considerably smaller than that of the conventional MPC, which effectively demonstrate the effectiveness of the proposed method. [ABSTRACT FROM AUTHOR]

This paper investigates thefiltering problem for stochastic systems driven by Poisson processes. By utilising the martingale theory such as the predictable projection operator and the dual predictable projection operator, this paper transforms the expectation of stochastic integral with respect to the Poisson process into the expectation of Lebesgue integral. Then, based on this, this paper designs anfilter such that the filtering error system is mean-square asymptotically stable and satisfies a prescribedperformance level. Finally, a simulation example is given to illustrate the effectiveness of the proposed filtering scheme. [ABSTRACT FROM AUTHOR]

This paper investigates the problem of swarm aggregations of heterogeneous multi-agent systems. Comparing with the existing studies on swarm aggregations of homogeneous multi-agent systems, this paper is much more resembling the practical situations, where the agents have different dynamics. We show that the heterogeneous agents will gather with a certain error under some assumptions and conditions. The stability properties have been proven by theoretical analysis and verified via numerical simulation. The stability of the heterogeneous multi-agent systems has been achieved based on matrix theory and the Lyapunov stability theorem. Numerical simulation is given to demonstrate the effectiveness of the theoretical result. [ABSTRACT FROM PUBLISHER]

In this paper, we consider a kind of stage-structured predator-prey systems with two predators and general functional responses. By applying the comparison theorem, Lyapunov functional and Mawhin's continuation theorem of coincidence degree theory, this paper gives some new sufficient conditions for the uniform persistence, globally asymptotical stability and almost-periodic solutions for the above system. Two examples and numerical simulations are provided to illustrate the main results of this paper. [ABSTRACT FROM AUTHOR]

In this paper, we consider the problem of constraint management in Linear Periodic (LP) systems using Reference Governors (RG). First, we introduce the periodic-invariant maximal output admissible sets for LP systems. We extend the earlier results in the literature to Lyapunov stable LP systems with output constraints, which arise in RG applications. We show that, while the invariant sets for these systems may not be finitely determined, a finitely-determined inner approximation, which is periodically invariant, can be obtained by constraint tightening. We then analyze the geometric and algebraic relationship between these sets and show that these sets are related via simple transformations, implying that it suffices to compute only one of them for real-time applications. This greatly reduces the memory burden of RG (or other similar constraint management strategies), at the expense of an increase in processing requirements. We present a thorough analysis of this trade-off. In the second part of this paper, we present two RG formulations, and discuss their properties and algorithms for their computation. Numerical simulations demonstrate the efficacy of the approach. [ABSTRACT FROM AUTHOR]

In this paper, a novel finite-time attitude control law is proposed for rigid–flexible coupling satellites in large angle manoeuver. First, the rigid–flexible coupling dynamic model is set up to reflect the coupling effect between the deformation of flexible appendages and the spatial movement of the rigid hub. Then an extended state observer (ESO) is designed to estimate and compensate the total perturbation including high-order flexible coupling terms, external disturbances and uncertain inertia. Following this, a continuous finite-time attitude controller is designed based on non-singular fast terminal sliding mode (NFTSM) and fast power reaching law, which is introduced to smooth the control input and eliminate the chattering. Numerical simulation is designed to verify the finite-time stability, high accuracy, disturbance rejectionand vibration damping of the proposed control scheme and then a ground experimental system is set to further test the controller's practicability. [ABSTRACT FROM AUTHOR]

This paper describes a solution to the problem of consensus/synchronisation for a general class of networked nonlinear multi-agent systems (MAS) using a distributed control strategy with an event-triggered communications (ETC) mechanism. We consider the case where the dynamics of each agent contain linear and Lipschitz nonlinear terms and the underlying communication graph is directed. The strategy proposed has two important properties: (i) it achieves practical consensus, i.e. the synchronisation error that measures the disagreement among the agents' states converges to a ball centred at the origin, with a radius that can be made arbitrarily small and (ii) the minimum of the inter-event times for each agent is lower bounded by a strictly positive number, hence Zeno behaviour is excluded. Furthermore, it affords system designers adequate tools to trade off the frequency of communications among agents against the level of performance achieved in MAS consensus/synchronisation. Numerical simulation results are also given. [ABSTRACT FROM AUTHOR]

This paper is concerned with the dynamics of a three-level food-chain model with time delays. By means of Mawhin's continuation theorem of coincidence degree theory, we investigate the existence of positive almost periodic solutions in a three-level food-chain model with time delays. A set of sufficient conditions for the existence of at least one positive almost periodic solution of the model is obtained. In addition, the global asymptotical stability of the almost periodic solution of the above model is also studied. Finally, two examples and simulations are also given to illustrate the main results in this paper. [ABSTRACT FROM AUTHOR]

This paper presents the cooperative preview control method for continuous-time multi-agent systems with a time-invariant directed communication topology. First, the cooperative tracking preview control problem is transformed into the optimal regulation problem of an augmented system. Next, by applying the results of the standard optimal preview control of continuous-time linear systems, a controller of the augmented system is obtained. Furthermore, the stabilisability and detectability of the augmented system are studied under the fixed digraph and the prescribed leader. Then, we derive the controller of multi-agent systems with error integral and preview action that can guarantee the achievement of cooperative optimal preview tracking. Finally, the effectiveness of the controller is shown by numerical simulations. [ABSTRACT FROM AUTHOR]

In this paper, we are concerned with dynamic stabilisation for a one-dimensional Euler–Bernoulli beam equation with boundary moment control and matched nonlinear uncertain disturbance. In the case of no disturbance, we show that a boundary feedback control law exponentially stabilises the system and Riesz basis generation holds for the closed-loop system. The well-posedness of the system in the sense of Salamon-Weiss, which is essentially important for the design of observer, is verified. We design an infinite-dimensional disturbance estimator, which doesn't need slow variation or high gain or boundedness of the derivation of the disturbance, to estimate the total disturbance. Based on the disturbance estimator, we design an output feedback control law. The Riesz basis generation and exponential stability of a couple system including the original equation is proved. Moreover, the boundedness of the closed-loop system is verified. Some numerical simulations are presented to illustrate the results. [ABSTRACT FROM AUTHOR]

It is known that the two controlled chaotic systems approach synchronization for any initial condition by proper controller design. Quite a number of alternative methods are available to synchronize the chaotic systems. Master-slave control technique is the most synchronization approaches used for the chaotic systems. In this paper, nonlinear active controller is obtained to synchronize the two identical dissipative fermionic systems in their chaotic states for different initial values. The synchronization is presented in the master–slave structure which implies that the states of the controlled chaotic slave system asymptotically synchronizes the states of the master system. Also the numerical simulations are given to show the effectiveness of the used controllers. [ABSTRACT FROM AUTHOR]

In this paper, based on Razumikhin method, stability of stochastic Lévy noise coupled systems with mixed delays (SLCSD) is researched. Here, both mixed delays and Lévy noise are considered into coupled systems for the first time. Then, by combining Razumikhin method with Lyapunov method and graph theory, several stability criteria including the Razumikhin-type theorem, the Lyapunov-type theorem and a coefficients-type theorem are given to ensure the pth moment exponential stability of SLCSD. In particular, the stability of a class of coupled oscillators and the stability of single-link robot arms are investigated as practical applications of the obtained results. And some numerical simulations are offered to illustrate the feasibility of the obtained results. [ABSTRACT FROM AUTHOR]

This paper develops a distributed algorithm for decision/awareness propagation in mobile-agent networks. A time-dependent proximity network topology is adopted to represent a mobile-agent scenario. The agent-interaction policy formulated here is inspired from the recently developed language-measure theory. Analytical results related to convergence of statistical moments of agent states are derived and then validated by numerical simulation. The results show that a single (user-defined) parameter in the agent interaction policy can be identified to control the trade-off betweenPropagation Radius(i.e. how far a decision spreads from its source) andLocalisation Gradient(i.e. the extent to which the spatial variations may affect localisation of the source) as well as the temporal convergence properties. ⋆An earlier version of the paper reporting preliminary results has been presented at the 2012 American Control Conference, Montreal, Canada. [ABSTRACT FROM PUBLISHER]

In this paper, the cluster consensus problem with delays of first-order nonlinear multi-agent systems is studied through pinning leader-following approach with periodic intermittent effect. The graph of the networked system is assumed to be directed and weakly connected. A new type of pinning consensus protocol with intermittent effect is designed according to the ways in which the agents link, specifically, the agents in each cluster are divided into three subsets due to the orientation of their topological degree, and each subset of agents is controlled by an individual law. A redefined notion on cluster consensus with two sorts of time delays is proposed in this article. Some consensus criteria are derived to guarantee that the agents in the same cluster asymptotically follow the virtual leader with a delay, while agents in different clusters reach consensus with delays via following their leaders. Some numerical simulations are given to illustrate the effectiveness of the theoretical results. [ABSTRACT FROM AUTHOR]

In this paper, a novel event-triggered observer is proposed to decrease the information exchange in continuous-time linear networked systems. The structure of the proposed observer consists of two main parts. The first one, called the event-triggered mechanism (ETM), is placed by the system and is used to determine when the measured output of the system must be sent through the network. The ETM consists of a traditional Luenberger observer, an event-triggered local observer, and an event-detector. The second part is a copy of the event-triggered local observer which is used to estimate the system state using the transmitted data from the sensors. Under the observability assumption, it is proved that the error between the system state and its estimation is asymptotically limited to a predetermined bound. Moreover, it is guaranteed that the Zeno behaviour is avoided. Numerical simulations are provided to demonstrate the design procedure of the proposed event-triggered observer. [ABSTRACT FROM AUTHOR]

In all existed researches on flocking control for multi-agent systems, each agent is modelled as a single point or covered by an circle, ellipse or rectangle; however, in case of limited space traffic systems, many complex vehicles cannot be fitted in these agent shapes. This paper proposes a distributed control law for two-dimensional multiple agents considered as arbitrarily polygonal shapes under limited communication ranges. The proposed control laws guarantee all flocking properties: each agent stays close to its nearby neighbours, no collision occurs in group of agents and velocity of each agent converges to a common vector. The designed control law based on a new anti-collision condition and potential function approach aims at dealing with the issue of collisions between agents. Further, the control signals are bounded and differentiable despite of agent's limited communication ranges and non-smooth boundary in agent shapes. Numerical simulations are implemented to demonstrate the performance of proposed control law for multiple agents with the same and different shapes. [ABSTRACT FROM AUTHOR]

In this paper, exponential finite-time coordination problems of multi-agent systems are investigated, including containment control and consensus. The theoretical basis is that a class of nonlinear systems has favourable finite-time convergence characteristic. For the objective of containment control, the proposed protocol ensures that the boundary agents in the same strong component exponentially reach a consensus and the internal agents exponentially converge to the convex hull spanned by the boundary agents in a finite time. For the objective of consensus, a pinning control strategy is designed for a fraction of agents such that all the agents exponentially reach a consensus with the leader in a finite time. The distinguished features of this paper lie in the following two points: (1) a smaller settling time of the Lyapunov function is obtained, which manifests in a faster convergence rate than the traditional one and (2) the weakly connected topology considered in this paper is more general than the ones (a spanning tree, a spanning forest, and so on) in other coordination problems. All the results are illustrated by some simulations. [ABSTRACT FROM AUTHOR]

This paper considers feedback systems with asymmetric (i.e., non-odd functions) nonlinear actuators and sensors. While the stability of such systems can be investigated using the theory of absolute stability and its extensions, the current paper provides a method for their performance analysis, i.e., reference tracking and disturbance rejection. Similar to the case of symmetric nonlinearities considered in earlier work, the development is based on the method of stochastic linearisation (which is akin to the describing functions, but intended to study general properties of dynamics, rather than periodic regimes). Unlike the symmetric case, however, the nonlinearities considered here must be approximated not only by a quasilinear gain, but a quasilinear bias as well. This paper derives transcendental equations for the quasilinear gain and bias, provides necessary and sufficient conditions for existence of their solutions, and, using simulations, investigates the accuracy of these solutions as a tool for predicting the quality of reference tracking and disturbance rejection. The method developed is then applied to performance analysis of specific systems, and the effect of asymmetry on their behaviour is investigated. In addition, this method is used to justify the recently discovered phenomenon of noise-induced loss of tracking in feedback systems with PI controllers, anti-windup, and sensor noise. [ABSTRACT FROM AUTHOR]

In this paper, both the closed-form dynamics and adaptive robust tracking control of a space robot with two-link flexible manipulators under unknown disturbances are developed. The dynamic model of the system is described with assumed modes approach and Lagrangian method. The flexible manipulators are represented as Euler-Bernoulli beams. Based on singular perturbation technique, the displacements/joint angles and flexible modes are modelled as slow and fast variables, respectively. A sliding mode control is designed for trajectories tracking of the slow subsystem under unknown but bounded disturbances, and an adaptive sliding mode control is derived for slow subsystem under unknown slowly time-varying disturbances. An optimal linear quadratic regulator method is proposed for the fast subsystem to damp out the vibrations of the flexible manipulators. Theoretical analysis validates the stability of the proposed composite controller. Numerical simulation results demonstrate the performance of the closed-loop flexible space robot system. [ABSTRACT FROM AUTHOR]