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Summary: In this study, the problem of preview tracking control (PTC) was considered with regard to the linear parameter periodic systems (LPPSs) subject to previewed signals. First, the difference operator approach was extended to derive an augmented error system (AES). As a result, the PTC problem was transformed into a stabilization problem via state/output feedback. Second, sufficient conditions guaranteeing the closed‐loop stability of the augmented error systems were derived, and the design of a periodic controller with preview actions was proposed through the approach of linear matrix inequalities (LMIs). Finally, a numerical simulation was performed to illustrate the effectiveness of the proposed periodic controller. [ABSTRACT FROM AUTHOR]

In this paper, the constrained control of systems evolving on matrix Lie groups with uncertainties is considered. The proposed methodology is composed of a nominal Model Predictive Control (MPC), and a feedback controller. The previous work on the control of systems on manifolds is applied to design the nominal MPC, which generates the nominal trajectory. In the nominal MPC, the state and input constraints on the Lie group are transformed into the constraints on the Euclidean space. While to deal with uncertainties, the feedback control used to track the nominal trajectory is designed directly on the Lie group. The tracking error in the feedback control is proved to be bounded in invariant sets, which are further used to revise the constraints in nominal MPC. We prove that the input‐to‐state stability of the entire system under the proposed control methodology with respect to the disturbances can be achieved. The proposed methodology is applied to the constrained attitude control of rigid bodies with uncertainties. In the application example, the detailed mathematical proof and the comparative numerical simulation are presented to demonstrate the feasibility of the proposed methodology. [ABSTRACT FROM AUTHOR]

In this paper, a protocol for nondestructive parity meter (NPM) of two cat‐state qubits is proposed. The physical model contains two cavities and an auxiliary qubit. For each cavity, the quantum information is encoded on the odd and even cat state, forming a cat‐state qubit. By adjusting the strength of the driving field on the auxiliary qubit, an effective Hamiltonian for cavity‐selective transition is derived. Moreover, reverse engineering based on the effective Hamiltonian is applied to find the evolution path, and the systematic‐error‐sensitivity nullification method is used to select proper parameters of the evolution path. In this way, robust control fields are designed to combat the influence of the systematic errors. Furthermore, the effects of random noise and decoherence on the fidelity of the protocol are considered. Numerical simulations show that the protocol is insensitive to the experimental imperfection, including systematic errors, random noise and decoherence. Therefore, the protocol is expected to expand the vision of realizing NPM. [ABSTRACT FROM AUTHOR]

Since the complexity nonlinearities generated by discontinuous control and event‐triggered scheme, fixed‐time formation in event‐based framework is a more challenging issue compared with the continuous‐time control. This paper focuses on fixed‐time leaderless formation problem for multi‐agent systems with undirected topology. We propose a distributed robust event‐triggered control strategy for the fixed‐time formation where predictor‐based state transformation is employed to deal with input delay and sliding mode technology is implemented to solve bounded disturbances. We also obtain that the upper bound of the formation settling time is only determined by delay time, control design parameters, network connectivity, and independent of the initial conditions. In addition, the lower bound for the interexecution time is calculated to ensure that there is no Zeno behavior occurs. Finally, some numerical simulations are presented to show the effectiveness of the strategies. [ABSTRACT FROM AUTHOR]

In this article, distributed tracking control is studied for multiple Euler–Lagrange systems in the presence of external disturbances and input saturation. Specifically, full‐state constraints, input saturation, communication delays, and unmeasured velocities are all considered simultaneously. First, a novel event‐triggered scheme is developed to save the communication source and reduce computational load. Second, the anti‐saturation compensation algorithm is exploited to compensate for system saturation. Third, an adaptive law is designed to offset external disturbances. Moreover, a high‐gain observer is employed to estimate unmeasured velocities. Theorem analysis shows the stability of the closed‐loop system, and numerical simulations are provided to verify the effectiveness of the proposed control strategy. [ABSTRACT FROM AUTHOR]

In this article, a novel robust finite‐time tracking control scheme is proposed for a class of uncertain nonlinear systems subject to the model uncertainty, external disturbance, and input saturation. A barrier function based disturbance observer (BFDO) with finite‐time convergence performance is developed to estimate the non‐smooth nonlinear compound disturbance, which includes the uncertainty, disturbance of system and input saturation. In addition, an adaptive continuous nonsingular terminal sliding mode controller, based on the barrier function and the estimate of the BFDO is developed. The Lyapunov stability and finite‐time convergence of the proposed control scheme are proved. The effectiveness and performance advantage of the proposed control scheme is demonstrated by numerical simulations and comparison with existing works. [ABSTRACT FROM AUTHOR]

This paper presents stability analyses on a towed underwater vehicle (TUV) motion control system using movable wings. The control method utilized is an output‐feedback controller based on linear state‐feedback control and a high‐gain observer. In order to analyze the closed‐loop stability of the system, the singular perturbation method is employed. Not only the asymptotic stability of the system is proved, but also an estimate of its region of attraction is derived. To describe a region of attraction, we propose a method by employing a hyper rhombus, which is quite suitable for quadratic Lyapunov functions. Further, to obtain a less conservative estimate, a state‐space‐scaling method is devised and its efficacy is evaluated by comparing with the conventional estimation method. Then, results of regulation simulations with various initial conditions are provided, which explores the consistency and gap between the theoretical estimate and the simulation results, and the robustness of the control system. Finally, a depth‐tracking control system via switching controllers is constructed according to the results of the stability analysis which investigates configuration of multiple equilibria with different depths and their regions of attraction, and demonstration simulation results are presented to illustrate the validity of the perspective given by the stability analysis. [ABSTRACT FROM AUTHOR]

This article studies the event‐triggered control problem for nonlinear systems that are merely integral input‐to‐state stable (iISS) with respect to measurement errors and external inputs. By using the iISS Lyapunov function, which comes from a necessary and sufficient condition on iISS, an integral‐based event‐triggering mechanism is introduced to compensate the effects of measurement errors. Under some assumptions on the gains of the iISS Lyapunov function, both the closed‐loop iISS and Zeno‐freeness are proved when the external inputs are measurable. In the presence of unknown disturbances, a novel switching event‐triggering mechanism is designed based on the relationship between the transmitted state and some threshold constant. Subsequently, the corresponding lower bound of inter‐event times is given explicitly to ensure Zeno‐freeness. It is shown that the proposed switching mechanism can be applicable to the nonlinear systems where some existing event‐triggering mechanisms are invalid in avoiding Zeno behavior. Finally, numerical simulations are provided to illustrate the efficiency and feasibility of the obtained results. [ABSTRACT FROM AUTHOR]

In this article, we propose a networked control architecture to ensure the plant's safety in the presence of cyber‐attacks on the communication channels. In particular, we consider systems subject to both state and input constraints that must be preserved for safety reasons despite any admissible attack scenario. To this end, first, two different detectors are proposed to detect attacks on the setpoint signal as well as on the control inputs and sensor measurements. Then, an emergency controller (EC), local to the plant, is designed to replace the networked controller whenever an attack is detected. Finally, the concept of robust N‐step attack‐safe region is introduced to ensure that the EC is activated, regardless of the detector performance, at least one‐step before the safety constraints are violated. It is formally proved that the plant trajectory is uniformly ultimately bounded in an admissible region regardless of the attacker's actions and duration. Finally, by considering a continuous‐stirred tank reactor system, numerical simulations are presented to show the proposed solution's capabilities. [ABSTRACT FROM AUTHOR]

Summary: The H∞ filtering problem for interconnected systems is addressed in this paper. In order to facilitate the stability analysis of interconnected systems under the conditions of failed interconnections, a strategy related to switched systems is introduced. Assume that the interconnections among these subsystems disconnect based on the mode‐dependent average dwell time (MDADT), a switching signal is implemented to denote the failed interconnections cases. In the aid of the MDADT method, a filter is designed such that the fault detection (FD) system is asymptotically stable and satisfies the weighted H∞ performance. Finally, a numerical simulation is provided to show the effectiveness of the proposed filter. [ABSTRACT FROM AUTHOR]

Summary: In this paper, a unified distributed robust control framework is proposed to address the power sharing problem for a cluster of dispatchable distributed generators (DDGs) within a grid‐connected AC microgrid. In contrast to the existing results, the advantages of the proposed control design are threefold. First, the unified design can directly handle the dynamics of the closed‐loop system by Lyapunov analysis without the assumption on time scale separation. Second, the canonical internal model is adopted so that the controller is able to undertake arbitrarily large parametric uncertainties. Last not least, the associated control gains can be obtained once and for all following the standard procedure. Comprehensive numerical simulations are provided for performance validation. [ABSTRACT FROM AUTHOR]

Summary: This article investigates the nonsingular prescribed‐time stabilization problem for p‐normal form systems. Two significant progresses are made for the first time as follows: First, a novel concept named coordinate mapping of time domain, is proposed to transform the nonsingular prescribed‐time convergence problem into the ordinary finite‐time convergence problem of transformed time‐varying system. Second, a set of new parameters are introduced to extend the existing adding a power integrator technique, such that the power restriction is removed. Based on above design procedure, a periodic controller is constructed to stabilize the state of the p‐normal form system into a small neighborhood of the equilibrium in prescribed time. Theoretical result is supported by numerical simulation. [ABSTRACT FROM AUTHOR]

Summary: This paper addresses the finite‐time and the prescribed finite‐time event‐triggered consensus tracking problems for second‐order multi‐agent systems (MASs) with uncertain disturbances. The prescribed finite‐time event‐triggered consensus of the second‐order disturbed MASs was obtained for the first time and the controller is nonsingular. Furthermore, a new self‐triggered control scheme is presented for the finite‐time consensus tracking, and the continuous communication can be avoided in the triggering condition monitoring. Hence, the finite‐time consensus tracking can be achieved with intermittent communication. Moreover, Zeno behavior is excluded for each follower. The efficiency of the proposed algorithms is verified by numerical simulations. [ABSTRACT FROM AUTHOR]

Summary: This paper proposes a robust active fault‐tolerant control (AFTC) approach for medium‐scale unmanned autonomous helicopter (UAH) with rotor flapping dynamics in the presence of unknown external disturbances and actuator faults. The robust items are adopted to improve the disturbance rejection capability of the UAH system. The adaptive fault observers are developed to estimate the fault parameters and the fault detection (FD) algorithms are presented to detect the actuator faults in different loops. In order to obtain satisfactory trajectory tracking performance, a backstepping‐based robust AFTC scheme is designed for the simplified 6‐degree‐of‐freedom (DOF) UAH nonlinear dynamics model and the global stability of the closed‐loop system is proved by using the Lyapunov method. Several groups of numerical simulation results are carried out to verify the effectiveness of the developed method. [ABSTRACT FROM AUTHOR]

Summary: For the high precise tracking control purpose of a cable‐driven manipulator under lumped uncertainties, a novel adaptive fractional‐order nonsingular terminal sliding mode control scheme based on time delay estimation (TDE) is proposed and investigated in this paper. The proposed control scheme mainly has three elements, ie, a TDE element applied to properly compensate the lumped unknown dynamics of the system resulting in a fascinating model‐free feature; a fractional‐order nonsingular terminal sliding mode (FONTSM) surface element used to ensure high precision in the steady phase; and a combined reaching law with adaptive technique adopted to obtain fast convergence and high precision and chatter reduction under complex lumped disturbance. Stability of the closed‐loop control system is analyzed with the Lyapunov stability theory. Comparative simulations and experiments were performed to demonstrate the effectiveness of our proposed control scheme using 2‐DOF (degree of freedom) of a cable‐driven manipulator named Polaris‐I. Corresponding results show that our proposed method can ensure faster convergence, higher precision, and better robustness against complex lumped disturbance than the existing TDE‐based FONTSM and continuous FONTSM control schemes. [ABSTRACT FROM AUTHOR]

Summary: Novel robust finite‐time stabilizing algorithms are developed side by side for the state and output feedback designs. Being initially developed for a nonlinear cascade second‐order system, these algorithms are straightforwardly extendible to electromechanical systems of relative degree two. The proposed synthesis is based on the disturbance compensation, relying on the dirty differentiation and sliding mode approach, and it is applicable to a wider class of disturbances than that addressed in the literature. Simulation results illustrate the efficiency of the resulting synthesis procedure and support analytical results. [ABSTRACT FROM AUTHOR]

Summary: The purpose of this paper is to present an extension of the generalised supertwisting algorithm (STA) to the multivariable framework. We begin by introducing an algorithm that may be deemed as a linear, quasicontinuous, or discontinuous multivariable system, depending on the functions that define them. For the class represented by such an algorithm we prove the robust, Lyapunov stability of the origin and characterise the perturbations that preserve its stability. In particular, when its vector field is discontinuous or quasicontinuous our algorithm is endowed with finite‐time stability. Due to its resemblance to the scalar case, we denote such finite‐time stable systems as generalised multivariable STA. Furthermore, the class of finite‐time stable systems comprise the currently available versions of STAs. To finalise, by means of simulation examples, we show that our proposed finite‐time stable algorithms are well suited for signals online differentiation and highlight their dynamical traits. [ABSTRACT FROM AUTHOR]

Abstract: Here, a protocol for robust preparation of an atomic concatenated Greenberger–Horne–Zeilinger (C‐GHZ) state via shortcuts to adiabaticity (STA) is proposed. The devices for implementing the protocol consist of atoms, cavities, and the optical fibers, which are feasible with current technology. The atoms are trapped in the separated cavities allowing individual control over each atom with classical fields. STA helps to design Rabi frequencies of classical fields so that the atoms can be driven from the initial states to the target states. The numerical simulations show that the protocol holds robustness against atomic spontaneous emissions and photonic leakages. Thus, the protocol may be realized by experiments in the near future. [ABSTRACT FROM AUTHOR]

A coupling frame (CF)-based high-frequency radio-frequency identification (HF RFID) card is composed of a metallic CF with a slot and a module (contains a small coil and an integrated circuit). This provides higher coupling and better performance in comparison to the standalone module. Such design eliminates the need for a mechanical connection between the module and card body (metal frame) which leads to reduced manufacturing costs. Further, it enhances the card's robustness against mechanical stress. The authors explain the operation of such a design from first principles and highlight the effect of the slot on the performance. In addition, a circuit model for the card is derived. Furthermore, they propose an enhancement to the card design which improves the card's performance with two variations either in terms of better transferred voltage (up to three times higher) or more bandwidth (up to double). The enhancement is shown by HFSS simulations, circuit simulations and corresponding measurements including the HF RFID integrated circuit. Finally, a double CF-based design is proposed and analysed which simultaneously achieves increased bandwidth and higher transferred voltage. The results are compared to those of conventional HF RFID cards with galvanic coupling to the integrated circuit. [ABSTRACT FROM AUTHOR]

The comprehensive design of uniform robust exact disturbance observer (UREDO) and fixed-time controller for reusable launch vehicles is investigated. A UREDO which can estimate the disturbance after a fixed-time independent of the initial error is presented. Based on the disturbance estimation, a non-singular terminal sliding mode controller is designed to ensure that the guidance command can be tracked within a fixed-time in the presence of model uncertainties and external disturbances. A proof of the fixed-time convergence of the closed-loop system under the control scheme is derived with complete stability analysis using the Lyapunov technique. The features of the proposed control scheme contain that the disturbance estimation, as well as the attitude tracking, can be achieved within a fixed-time, which is independent of initial conditions and the derivative information of states is not essential, which is valuable in engineering application. Numerical simulations are performed to demonstrate the fixed-time convergence performance of the proposed control scheme. [ABSTRACT FROM AUTHOR]

Summary: In this paper, the problem of formation control is considered for a class of unknown nonaffine nonlinear multiagent systems under a repeatable operation environment. To achieve the formation objective, the unknown nonlinear agent's dynamic is first transformed into a compact form dynamic linearization model along the iteration axis. Then, a distributed model‐free adaptive iterative learning control scheme is designed to ensure that all agents can keep their desired deviations from the reference trajectory over the whole time interval. The main results are given for the multiagent systems with fixed communication topologies and the extension to the switching topologies case is also discussed. The feature of this design is that formation control can be solved only depending on the input/output data of each agent. An example is given to demonstrate the effectiveness of the proposed method. [ABSTRACT FROM AUTHOR]

Summary: This paper describes a new robust model predictive control (MPC) scheme to control the discrete‐time linear parameter‐varying input‐output models subject to input and output constraints. Closed‐loop asymptotic stability is guaranteed by including a quadratic terminal cost and an ellipsoidal terminal set, which are solved offline, for the underlying online MPC optimization problem. The main attractive feature of the proposed scheme in comparison with previously published results is that all offline computations are now based on the convex optimization problem, which significantly reduces conservatism and computational complexity. Moreover, the proposed scheme can handle a wider class of linear parameter‐varying input‐output models than those considered by previous schemes without increasing the complexity. For an illustration, the predictive control of a continuously stirred tank reactor is provided with the proposed method. [ABSTRACT FROM AUTHOR]

Summary: In this article, the problems of modeling and controlling are investigated for a suspension cable system of a helicopter with input saturation, system parameter uncertainties, and external disturbances by using the boundary control method. In accordance with the Hamilton's principle, the model of the suspension cable system of a helicopter is established by using a set of partial differential and ordinary differential equations. Considering nonsymmetric saturation constraint, the auxiliary systems are designed to handle with the effect of input saturation. Considering Lyapunov's direct method and the designed auxiliary systems, two robust adaptive boundary controllers are provided by the actuators at the helicopter and the box. Under the proposed controllers, the error between the bottom payload and the target location and the vibration range are uniformly ultimately bounded. Moreover, they will converge to a small neighborhood of zero by selecting the suitable parameters. Meanwhile, to guarantee the validity of the proposed adaptive boundary control laws, some sufficient conditions are raised. Simulation results are provided to verify that the effectiveness of the designed controllers in this paper. [ABSTRACT FROM AUTHOR]

Abstract: This paper investigates the robust model predictive control (RMPC) problem for a class of linear discrete‐time systems subject to saturated inputs and randomly occurring uncertainties (ROUs). Due to limited bandwidth of the network channels, the networked transmission would inevitably lead to incomplete measurements and subsequently unavoidable network‐induced phenomenon that include saturated inputs as a special case. The saturated inputs are assumed to be sector‐bounded in the underlying system. In addition, the ROUs are taken into account to reflect the difficulties in precise system modelling, where the norm‐bounded uncertainties are governed by certain uncorrelated Bernoulli‐distributed white noise sequences with known conditional probabilities. Based on the invariant set theory, a sufficient condition is derived to guarantee the robust stability in the mean‐square sense of the closed‐loop system. By employing the convex optimization technique, the controller gain is obtained by solving an optimization problem with some inequality constraints. Finally, a simulation example is employed to demonstrate the effectiveness of the proposed RMPC scheme. [ABSTRACT FROM AUTHOR]

Abstract: In this paper, we propose an online algebraic method to identify linear continuous time delay process from step response, in presence of unknown initial state and constant load disturbance. The identification mechanism is split into two sequential steps. The time delay and dynamic of the plant is estimated firstly through a spectral formulation. In the next stage, the transient regime is deduced from a linear regression. To improve the robustness of the proposed method, a local convolution by sigmoid function is proposed. Simulation results are provided, at last, to show the effectiveness of our conceived approach. [ABSTRACT FROM AUTHOR]

Abstract: Phase‐field methods for brittle fracture employ a variational framework and have proven to predict complex fracture patterns in two and three dimensional examples. This contribution focuses on a phase‐field approach for a coupled field model of brittle pneumatic fracture. Two different challenges are tackled in this contribution: First, we have to deal with pressure‐driven processes within the proposed phase‐field ansatz, second, we have to consider the numerical effort of the simulations. Our phase‐field formulation is based on elasticity and a suitable operator split to take only the tensile parts into account. Furthermore, a prescribed pressure is coupled with the phase‐field parameter to consider crack propagation induced by pneumatic pressure. To keep the numerical effort as small as possible we apply a specifically developed multigrid method for three‐dimensional problems. The accuracy and the robustness of the solution method will be demonstrated with a series of numerical examples. (© 2017 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim) [ABSTRACT FROM AUTHOR]

A fault diagnosis and compensation problem for two-dimensional discrete time systems with time-varying state delays is studied in this paper. The concerned two-dimensional systems are described by the Fornasisi-Marchesini second model and are subject to unknown disturbances. First, a fault detection and diagnosis module is designed to obtain the information on sensor faults; a new fault detection and diagnosis integrated design, using the observer based on descriptor system approach, is proposed to detect and estimate the sensor faults. The integrated design can maximize the fault detection rate for a given false alarm rate. Sufficient conditions for the existence of the integrated fault detection and diagnosis design are derived in the context of norm evaluation and provided in terms of matrix inequalities. Second, a fault-tolerant control module is proposed upon an existing output feedback controller. When the sensor fault occurs, the faulty measurement can be identified and corrected by the proposed fault detection and diagnosis module. In this case, the feedback controller can guarantee the performance of the closed-loop system even when encountering sensor faults. Finally, the proposed method is applied to a thermal process to illustrate its effectiveness. Copyright © 2017 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

In this paper, we apply the active disturbance rejection control approach to output-feedback stabilization for uncertain lower triangular nonlinear systems with stochastic inverse dynamics and stochastic disturbance. We first design an extended state observer (ESO) to estimate both unmeasured states and stochastic total disturbance that includes unknown system dynamics, unknown stochastic inverse dynamics, external stochastic disturbance, and uncertainty caused by the deviation of control parameter from its nominal value. The stochastic total disturbance is then compensated in the feedback loop. The constant gain and the time-varying gain are used in ESO design separately. The mean square practical stability for the closed-loop system with constant gain ESO and the mean square asymptotic stability with time-varying gain ESO are developed, respectively. Some numerical simulations are presented to demonstrate the effectiveness of the proposed output-feedback control scheme. Copyright © 2016 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

A generalized homogeneous exact set-point tracking control methodology for a class of disturbed higher-order nonlinear systems is investigated in this paper. By virtue of utilizing the disturbance estimation and active elimination approach, a homogeneous domination feedback technique is then integrated such that a generalized composite active anti-disturbance control framework is proposed with a delicate handling procedure of the non-vanishing nonlinearities. The proposed methodology has several new features. First, a genuine nonlinear composite controller employing the system nonlinearities will bring an improvement of the control performances. Second, the flexility of the design methodology renders its suitability for random output tracking with mismatched disturbances in every channel. Moreover, the control function is constructed in a neat nested form and hence easier to be implemented. Numerical simulation results affirm the output tracking control performances. Copyright © 2016 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

This paper deals with the design of a robust sliding mode-based extremum-seeking controller aimed at the online optimization of a class of uncertain reaction systems. The design methodology is based on an input-output linearizing method with variable-structure feedback, such that the closed-loop system converges to a neighborhood of the optimal set point with sliding mode motion. In contrast with previous extremum-seeking control algorithms, the control scheme includes a dynamic modelling-error estimator to compensate for unknown terms related with model uncertainties and unmeasured disturbances. The proposed online optimization scheme does not make use of a dither signal or a gradient-based optimization algorithm. Practical stabilizability for the closed-loop system around to the unknown optimal set point is analyzed. Numerical experiments for two nonlinear processes illustrate the effectiveness of the proposed robust control scheme. Copyright © 2017 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

This paper deals with the robust finite time tracking of desired trajectories for a wide group of robotic manipulators in spite of unknown disturbances, uncertainties, and saturations of actuators while only manipulator's positions are available and its velocities are not measurable physically. A new form of chattering-free second order fast nonsingular terminal sliding mode control scheme is introduced to design input torques for fulfilling the determined tracking objective in the adjustable total finite settling time. The proposed control algorithm is incorporated with two nonlinear observers to estimate disturbances and velocities of joints within finite settling times. The global finite time stability of the closed-loop manipulator is analytically proved. Finally, a numerical simulation is carried out to verify the effectiveness of the designed input torques. Copyright © 2017 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

This paper presents a systematic method to address the reduction of online computational complexity and infeasibility problem of explicit model predictive control for constrained systems under external disturbance. In feasible state space, in order to avoid the expensive database searching procedure, support vector machine-based approximation is proposed to yield a novel unified explicit optimal control law rather than a piecewise affine one developed by explicit model predictive control. In infeasible state space, through constructing finite maximum control invariant sets around fictitious equilibrium points, a reachable controller is devised to steer the infeasible state asymptotically to the feasible state space without violating the hard constraint. Consequently, global robustness is guaranteed by introducing a minimum robust positively invariant set by means of the tube-based technique, despite the coexistence of external disturbance and training error. Finally, the performance of the presently proposed control law is evaluated through three groups of numerical examples. Copyright © 2016 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

In this paper, the delayed state fractional order derivative (DSFOD) is introduced into the existing traditional consensus protocol aiming to improve the robustness of fractional-order multi-agent systems against communication time delay. Both of communication channels with time-delay and without time-delay cases are considered. Based on the frequency-domain analysis and algebraic graph theory, it is shown that properly choosing the intensity of DSFOD can improve the robustness of fractional-order multi-agent systems against communication delay. Finally, a simulated example with simulations is presented to confirm the correctness and effectiveness of the theoretical results. [ABSTRACT FROM AUTHOR]

In this paper, a new event-switched control method is presented for controlling discrete-time linear systems subject to bounded disturbances. The main advantage of the proposed method is that the nominal performance of the controlled system with periodic control updates is kept in a framework that do not require to periodically update the control law. The feedback control loop can be opened as long a state-dependent event condition is satisfied. This condition is obtained using set theory approaches. In particular, the concept of robustly positively invariant sets is used to calculate the nominal performance and the event condition. The simulation presented in this paper confirms the efficiency of the present approach. A reduction of the numerical complexity of the approach is also proposed. Copyright © 2016 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

A robust consensus controller is proposed for heterogeneous higher-order nonlinear multi-agent systems, when the agent dynamics are involved with mismatched uncertainties. A distributed consensus protocol based on a time-varying nonhomogeneous finite-time disturbance observer and sliding mode control is designed to realize the network consensus of higher-order multi-agent systems. The time-varying finite-time disturbance observer overcomes the problem of peaking value near the initial time caused by the constant gain one and is designed to estimate the uncertainties and to mitigate the effect of mismatched uncertainties during the sliding mode. To eliminate the chattering phenomenon and ensure finite-time convergence to the sliding surface, the control law is designed by using the super twisting algorithm. Finally numerical simulations are given to illustrate the validity of the proposed method. Copyright © 2016 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

In this paper, robust containment problem is investigated for a class of multi-leader multi-agent linear systems in the presence of time-varying uncertainties. To achieve containment, a new kind of adaptive containment protocols are proposed for the multi-agent systems. Specifically, the designed protocols consist of a continuous linear term and a discontinuous term. The linear term of the designed protocol is employed to achieve containment while the discontinuous term is utilized to eliminate the effect of uncertain dynamics on the achievement of containment. By using tools from non-smooth analysis and algebraic graph theory, some efficient criteria for achieving robust containment in the closed-loop multi-agent systems are obtained and analyzed. One favorable property of the designed protocol is that containment in the closed-loop multi-agent systems can be achieved in a fully distributed fashion over any given connected and detail-balanced communication graph without using any global information about the communication graph. The effectiveness of the analytical results is finally verified by performing numerical simulations. Copyright © 2016 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

This paper addresses the problem of advanced testing of systems via the principle of dynamic substructuring. Use is made of the hybrid simulation (HS) scheme framework to develop a new method of synthesis for the dynamically substructured system (DSS) scheme of Stoten and Hyde. Principal reasons for doing this are (i) to improve upon the original method of DSS synthesis by adopting the more intuitive framework of HS and (ii) to enable the amalgamation of HS and DSS into a unified substructured system (USS) scheme, so that the significant advantages of DSS can be incorporated into an existing HS scheme as a straightforward retrofit. Having established the common framework for HS/DSS, the paper also illustrates, by way of an example, compensator/controller synthesis for the two schemes, together with their advantages and disadvantages. In doing this, both schemes are retained in their basic forms, that is, there are no additional control embellishments used in this work, such as delay compensation, adaptive control, or other advanced control methods. In order to maintain as much transparency as possible, use is made of well-known classical control techniques. Common problems associated with the substructure testing technique are also investigated, including the effects of physical parameter uncertainty, pure delays in signals, and a 'split-mass' in the substructure formulation. It is shown that, although the new formulation of controlled DSS requires more design effort than compensated-HS, the advantages of DSS in terms of stability and robustness significantly outweigh this small disadvantage at the design stage. Copyright © 2016 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

A novel output feedback dynamic excitation control scheme is proposed for efficient load angle trajectory tracking tasks for synchronous generators. In this way, effective tracking of reference trajectories for the state variables and electric power is also guaranteed. The introduced control design approach is robust against parametric uncertainty, unmodelled dynamics, and variable mechanical power input commonly present in practical electric power systems. The control scheme only requires measurements of the load angle variable, and state and disturbance estimation is properly avoided. Computer simulation results are included to show the controller robustness and the satisfactory reference trajectory tracking specified for the machine operation for both continuous and switched control voltage signals. [ABSTRACT FROM AUTHOR]

Design of experiments for identification of control-relevant models is at the heart of robust controller design. In a number of prior publications, experiment designs have been developed that generate input/output data for efficient identification of models satisfying the integral controllability (IC) condition. The design of process inputs for such experiments is often, but not always, based on the concept of independent random rotated inputs, with appropriately proportioned amplitudes. However, prior publications do not account for models that may already be partially known before identification. In this work, this issue is addressed by developing a general experiment design framework for efficient identification of partially known models that must satisfy the IC condition. This framework produces optimal designs by solving appropriately formulated optimization problems, based on a number of rigorous theoretical results. Numerical simulations illustrate the proposed approach and potential future extensions are suggested. © 2016 American Institute of Chemical Engineers AIChE J, 62: 2986-3001, 2016 [ABSTRACT FROM AUTHOR]

A variable structure model-reference adaptive control (VS-MRAC) of impedances and admittances (driving-point (DP) functions) is proposed. Only voltage and current measurements are required to implement the controllers. The inclusion of a prefilter in the reference model allows the synthesis of quite general DP functions, even with nonminimum phase zeros and unstable poles. It is shown that the stability of the closed-loop system depends only on the source DP function and the chosen reference model. The VS-MRAC guarantees global exponential stability properties, robustness to parameter uncertainties, disturbances, and unmodelled dynamics. Simulation results illustrate the performance and robustness of the VS-MRAC. Copyright © 2016 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

This paper extends the existing proximate time-optimal servomechanism control methodology to the more typical second-order servo systems with a damping element. A parameterized design of expanded proximate time-optimal servomechanism control law with a speed-dependent linear region is presented for rapid and smooth set-point tracking using a bounded input signal. The control scheme uses the time-optimal bangbang control law to accomplish maximum acceleration or braking whenever appropriate and then smoothly switches into a linear control law to achieve a bumpless settling. The closed-loop stability is analyzed, and then the control scheme is applied to the position--velocity control loop in a permanent magnet synchronous motor servo system for set-point position regulation. Numerical simulation has been conducted, followed by experimental verification based on a TMS320F2812 digital signal controller board. The results confirm that the servo system can track a wide range of target references with superior transient performance and steady-state accuracy. [ABSTRACT FROM AUTHOR]

A novel three-dimensional fault-tolerant control guidance law is proposed for interception of maneuvering targets in the presence of external disturbances, actuator failures, and control input constraints. The input-to-state stability (ISS) method is introduced to design the fault-tolerant control guidance law to guarantee robust tracking of a maneuvering target. Then, a saturated fault-tolerant control guidance law is constructed using a modified saturation function to ensure the resulting control signal will never incur input constraints, and the convergence to a small neighborhood of origin is ensured in theory. Simulation results show that the presented approach is effective in achieving a successful interception against target maneuvers, external disturbances, actuator failures, and control input constraints. [ABSTRACT FROM AUTHOR]

The proposed method computes a navigation mesh for arbitrary and dynamic 3D environments based on curvature and is robust and efficient. This method addresses a number of known limitations in state-of-the-art techniques to produce navigation meshes that are tightly coupled to the original geometry, incorporate geometric details that are crucial for movement decisions, can robustly handle complex surfaces and can efficiently repair the navigation mesh to accommodate dynamically changing environments. The method is integrated into a standard navigation and collision avoidance system to simulate thousands of agents on complex 3D surfaces in real time. Copyright © 2016 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

An outline of the improvements to the pseudospectral electronic structure program Jaguar is presented, showing efficient and robust performance of hybrid-DFT calculations for large systems with thousands of basis functions, focusing on materials applications. The improvements include re-engineered parallelization, the design of a fragment-based initial guess generation method, and the validation of small eigenvalue cutoff values. An OpenMP/MPI hybrid parallelization has been implemented for the pseudospectral algorithm, which extends Jaguar's scalability to up to 256 cores in tests of TiO2 clusters with 1295-4961 basis functions. In the largest test case, the code delivers 84.4× speedup for 128 cores in total calculation time. In addition, a fragment-based initial guess method has been constructed for large systems containing many transition metals, where the conventional (atomic) approach often fails. Overall, Jaguar is now capable of efficiently and robustly performing hybrid-DFT geometrical optimizations for large systems with more than 600 atoms in reasonable runtimes. © 2015 Wiley Periodicals, Inc. [ABSTRACT FROM AUTHOR]

In this paper, we study the robust consensus tracking problem for a class of high-order multi-agent systems with unmodelled dynamics and unknown disturbances. A continuous robust state feedback control algorithm is proposed to enable the agents to achieve robust consensus tracking of a desired trajectory. By utilizing Lyapunov analysis methods and an invariance-like theorem, sufficient conditions for semi-global asymptotic consensus tracking are established. A robust output feedback control algorithm is designed to obtain a uniformly ultimately bounded consensus tracking result. Numerical simulations are provided to show the effectiveness of the proposed algorithms. Copyright © 2015 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

In this paper, a new model is proposed to describe networked control systems (NCS) with delays and quantization errors. Firstly, the non-idealizations are unified in the classic robust control framework and the entire system is modeled as a discrete system closed via a block uncertainty. Then, the stability criteria are derived using small gain theorem, μ tool and integral quadratic constraint (IQC) method, respectively. Finally, a simulation and a numerical example are provided to demonstrate the effectiveness of the proposed methods. This work is supported by the Science Foundation of China University of Petroleum, Beijing (No.YJRC-2013-11) and National Natural Science Foundation (NNSF) of China under Grant 61374033. [ABSTRACT FROM AUTHOR]

This study presents the design of a robust active disturbance rejection (ADR) controller in order to improve lowvoltage ride-through (LVRT) capability of wind farms connected with doubly fed induction generator (DFIG). The ADR controller is particularly effective in real-time estimation and mitigation of the total effect of various uncertainties against a wide range of parameter variations, model uncertainties and large disturbances. The performance evaluation of the designed controller is performed on an IEEE system under different test cases. The simulation results show that the proposed controller is robust against uncertainties in operating conditions and successfully improves the damping and voltage stability and thus the LVRT capability of DFIGs. [ABSTRACT FROM AUTHOR]

A device with bulk and source interleaved dotting is fabricated in a 0.5-µm 24 V CDMOS process, and the root cause of why it improves the multi-finger high-voltage lateral double-diffused MOS (LDMOS)'s electrostatic discharge (ESD) robustness is detected by Atlas three-dimensional device simulation and transmission line pulse system. Such device structure obtains strong ESD robustness by enlarging the intrinsic base resistance without increasing device area and sacrificing any ESD performance of nLDMOS. The measurement results demonstrated that, compared with traditional gate-grounded nLDMOS (GG-nLDMOS) with a total length of 400 µm, the proposed device can effectively raise the secondary breakdown current (It2) from 2.43 A up to 5.55 A, and enhance the ESD current discharge efficiency from 0.29 to 0.70 mA/µm². [ABSTRACT FROM AUTHOR]

Integrated guidance and control of an elastic flight vehicle based on constrained robust model predictive control is proposed. The design is based on a partial state feedback control law that minimizes a cost function within the framework of linear matrix inequalities. It is shown that the solution of the defined optimization problem stabilizes the nonlinear plant. Nonlinear kinematics and dynamics are taken into account, and internal stability of the closed-loop nonlinear system is guaranteed. The performance and effectiveness of the proposed integrated guidance and control against non-maneuvering and weaving targets are evaluated using computer simulations. Copyright © 2014 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

This paper investigates the distributed robust finite-time attitude containment control for multiple rigid bodies with uncertainties including parametric uncertainties, external disturbances, and actuator failures. Two novel types of distributed control laws are designed corresponding to two different cases, respectively, and both of them can drive the orientations of the followers into the convex hull formed by the orientations of leaders in a finite time. Simulation results show the effectiveness of the proposed design. Copyright © 2014 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]