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For a class of nontriangular nonlinear systems in presence of unknown disturbances, we propose a predictor-based neural dynamic surface control (PNDSC) strategy in this paper. This nontriangular system is transformed via the mean value theorem, and a predictor is then constructed. To avoid an algebraic loop problem, partial state vectors are employed as input signals of neural networks (NNs) for approximating unknown dynamics, and compensation items are designed to compensate for approximation errors from NNs. Different from the traditional NDSC, the PNDSC in this paper utilizes prediction errors to update learning parameters for improving NNs’ learning behaviors with overlarge adaptive gains. On the basis of improved NNs’ approximation behaviors, a predictor-based NNs disturbance observer (PNNDO) is constructed for compensation for external disturbances and approximation errors from NNs. Furthermore, with predictors, a normalization method of weights is developed to reduce the number of online learning parameters. On the basis of the aforementioned result, measurement noises are taken into account in our predictor-based neural control strategy. We employ predictor states, rather than measurement information paralyzed by noises, in design of our control strategy. This reduces high-frequency oscillations in control input. A Lyapunov-based stability analysis shows that all signals are ultimately bounded in the closed-loop system. Finally, the effectiveness of the proposed control strategy is verified by a numerical example and a permanent magnet brushless DC motor system. [ABSTRACT FROM AUTHOR]

The device faults commonly exist in microgrids (MGs) and often undermine the system stability. However, the existing distributed methods generally design control protocols based on the absence of faults or only considering actuator faults, which limits the applicability of controllers in MG systems. Therefore, this paper investigates an adaptive prescribed fixed-time performance (PFTP) consensus fault-tolerant control (FTC) problem for the voltage regulation of a nonlinear islanded MG inverter-based distributed generators (DGs) with output contactor and actuator fault via the state event-triggered mechanism. The PFTP method for the voltage restoration synchronization error is proposed by constructing a novel performance function to increase the speed of voltage recovery. Based on the estimation properties of fuzzy logic system, an unknown nonlinear function and the residual term of output contactor are estimated. Then, an adaptive state event-triggering mechanism is designed to reduce the communication burden, and its main advantage is that the control protocol is updated in the aperiodic way at the triggering instants. Further, according to backstepping technology, a novel adaptive event-triggered consensus FTC protocol is constructed to achieve the voltage regulation of islanded MG, and a parameter adaptive law is designed to compensate the adverse effects of the output contactor fault. Based on the Lyapunov stability theory, it is proved that the voltage recovery synchronization error satisfies the PFTP, and all signals in the closed-loop systems are cooperatively uniformly ultimately bounded. Finally, the proposed control strategy is also validated by using the MATLAB. [ABSTRACT FROM AUTHOR]

In this paper, the finite-time sliding mode control issue is studied for a series of semi-Markov jump systems subject to actuator faults, where an asynchronous control method is adopted to overcome the non-synchronous phenomenon between the system mode and controller mode. Additionally, the event-triggered protocol, which determines whether the transmission of data should be performed according to the threshold condition, is introduced to alleviate the burden of data transmission in the communication channel. This paper aims to devise an asynchronous event-triggered sliding mode control law so as to guarantee the trajectories of the resulting closed-loop system can be forced onto the predefined sliding surface in a finite-time interval. Thence, by means of the mode-dependent Lyapunov functions and the finite-time theory, sufficient conditions are derived to assure that the closed-loop system is mean-square finite-time bounded in both reaching and sliding motion phases. Eventually, a numerical example and a tunnel diode circuit model are presented to illustrate the availability and practicability of the proposed approach. [ABSTRACT FROM AUTHOR]

In this paper, a composite velocity-tracking control scheme is presented for improving dynamics response and control accuracy of the flexible gimbal system in the control moment gyro (CMG). Specifically, an ${H}_{\infty } $ optimal vibration controller (HOVC) is developed to weigh multi-performance of the gimbal system, such as stability, fast-tracking performance, and attenuation ability of multi-frequency-band disturbances. Meanwhile, a robust disturbance observer (RDO) designed on optimization technology is utilized to improve the nonlinear friction rejection ability of the gimbal system. Moreover, rigorous theoretical analysis based on the small-gain theory is provided to demonstrate the stability of the closed-loop gimbal system under multiple disturbances. Finally, experimental studies are presented to verify the effectiveness of the proposed method. [ABSTRACT FROM AUTHOR]

In this paper, based on sampled-data control method, we address the stabilization problem for a general class of linear continuous-time fractional systems whose solution contains the Mittag-Leffler function that does not obey the basic exponentiation identity. By considering the infinite memory and hereditary characteristics of fractional-order calculus, we propose a sampled-data controller that guarantees the resulting closed-loop system to be asymptotically stable. Simulation examples are presented to demonstrate the effectiveness of the proposed controller and verify the established results. [ABSTRACT FROM AUTHOR]

This paper investigates the leader-following consensus control problem for a class of nonlinear multiagent systems subject to sensor and actuator faults under a fixed directed graph. First, a fault compensation mechanism is proposed because of multiple faults wherein the adaptive parameters substitute the fault coefficients. Then, the command filtering method is employed to avoid the burst of complexity rendered by the duplicative differentiation of the virtual control signal. Furthermore, the neural networks-based state observers are designed to reconstruct the unmeasurable states of the nonlinear multiagent systems. According to the given design approach, a switching threshold-based event-triggered adaptive fault-tolerant control strategy is developed and ensures all the signals in the closed-loop system are semiglobally uniformly ultimately bounded (SGUUB). Finally, the simulation result is provided to demonstrate the validity of the presented method. [ABSTRACT FROM AUTHOR]

In this paper, global event-triggered adaptive prescribed tracking output feedback control is investigated for a class of nonlinear uncertain systems with unknown control direction. Different from the existing works, the design of the tracking error-dependent normalized function and prescribed boundary is based on our uniformly defined blow-up function rather than a specific function, and the asymmetric constraint requirements on tracking error can be achieved by appropriately selecting the blow-up function. By utilizing the Kalman filter ($K$ -filter) and dynamic gain technique, a new reduce-order observer is proposed, which can make the estimated error exponentially converge to zero. In addition, by introducing a dynamic signal into the trigger condition, a novel event-triggered mechanism is proposed, which can extend the trigger time interval and completely counteract the event-triggered errors in terms of asymptotic stability by sacrificing part of the system transient performance. Furthermore, an adaptive controller is designed based on the backstepping method, which ensures the boundedness of the state of the closed-loop system, while regulating the tracking error meets the global prescribed performance requirements and approaches to zero asymptotically. Two examples are given to illustrate the effectiveness of the proposed control scheme. [ABSTRACT FROM AUTHOR]

This paper studies the prescribed-time input-to-state stabilization problem of normal nonlinear systems. With the help of some key properties of a class of parametric Lyapunov equations, the prescribed-time input-to-state stabilization problem of normal nonlinear systems under matched uncertainties is studied. Some bounded time-varying controllers are proposed. It is shown that the closed-loop systems are prescribed-time input-to-state stable. Finally, the effectiveness of the established methods is illustrated by two physical systems. [ABSTRACT FROM AUTHOR]

This paper designs a novel nonsingular terminal sliding mode control (TSMC) scheme for a class of nonlinear systems under binary encoding transmission. To further ease the communication overheads between the plant and the controller, a dynamic event-triggered mechanism is also introduced to the TSMC design. Sufficient conditions are proposed, respectively, for guaranteeing the reachability to a practical sliding mode and the ultimate boundedness of the closed-loop system, in which the effects from the binary encoding and the dynamic event-triggered protocol are quantified clearly. The Zeno phenomena for the developed dynamic event-triggered mechanism is excluded via an explicit analysis. Finally, the feasibility and effectiveness of the proposed scheme are demonstrated by a numerical example and a real experiment on permanent magnet synchronous motor speed regulation system. [ABSTRACT FROM AUTHOR]

In this paper, an event-triggered optimal tracking control of discrete-time multi-agent systems is addressed by using reinforcement learning. In contrast to traditional reinforcement learning-based methods for optimal coordination and control of multi-agent systems with a time-triggered control mechanism, an event-triggered mechanism is proposed to update the controller only when the designed events are triggered, which reduces the computational burden and transmission load. The stability analysis of the closed-loop multi-agent systems with event-triggered controller is described. Further, to implement the proposed scheme, an actor-critic neural network learning structure is proposed to approximate performance indices and to on-line learn the event-triggered optimal control. During the training process, event-triggered weight tuning law has been designed, wherein the weight parameters of the actor neural networks are adjusted only during triggering instances compared with traditional methods with fixed updating periods. Further, a convergence analysis of the actor-critic neural network is provided via Lyapunov method. Finally, two simulation examples show the effectiveness and performance of the obtained event-triggered reinforcement learning controller. [ABSTRACT FROM AUTHOR]

There are practical applications requiring the wireless power transfer (WPT) system to supply multiple output voltages to a variety of loads. In this paper, in order to achieve this goal, multiple double T resonant circuits are connected to the common port of the receiver side. Based on the modeling and analysis of the double T resonant circuit, it is found that the load-independent output and input zero phase angle (ZPA) can be derived. The proposed WPT system presents the following merits: 1) output voltages are load independent and can be controlled synchronously against the disturbance from input DC source and mutual coupling by using only one closed loop; 2) the output voltages can be adjusted individually to different levels by configuring circuit parameters; 3) only passive components are used to achieve multiple outputs. The power loss can be reduced due to the parasitic resistance of the passive component is very small and can be negligible; and 4) the reactive power losses are minimized due to the input ZPA of the system. An experimental prototype with two output channels is built, based on which the load independent and the controllable characteristics of the output voltages are verified. [ABSTRACT FROM AUTHOR]

This paper studies stability for a class of switched descriptor systems with state bumpless transfer performance and input bumpless transfer performance. Since the state jump is inevitable for switched descriptor systems when a switching occurs, to restrain the amplitude of the state jump induced by switchings, for the first time, the state bumpless transfer performance of switched descriptor systems is defined. Moreover, when switching occurs, to avoid the abrupt and large control input signals change damaging the system, we are the first to introduce the input bumpless transfer control scheme for switched descriptor systems. Furthermore, by using multiple Lyapunov functions, a sufficient condition is put forward to make sure the state bumpless transfer performance, input bumpless transfer performance and asymptotical stability for the closed-loop systems. Meanwhile, the switching rule and the state feedback controller are co-designed. In the end, a multiple inputs numerical example and an application on the DC motor model are used to exhibit the merit and validity of the presented control scheme. [ABSTRACT FROM AUTHOR]

This paper studies the event-triggered robust model predictive control (MPC) problem for constrained linear systems subject to bounded disturbances. For control computations, explicit MPC reduces online optimizations to simple function evaluations, thus is suitable for resource constrained systems. We propose an event-triggering mechanism (ETM) for an explicit robust model predictive controller such that function evaluations are not needed at every time instant and the ETM itself requires comparably less online computations. In the proposed ETM, we design a contracting polytopic trigger set with respect to system constraints and the explicit robust control law. The resulting event-triggered control scheme ensures robust constraint satisfaction and robust stability for the closed-loop system while avoiding the Zeno-like behavior. Simulation results illustrate the validity of the event-triggered robust control scheme. [ABSTRACT FROM AUTHOR]

This paper considers the control problem of p-norm stochastic nonlinear systems with output constraints, while the system nonlinearities are completely unknown and the system states are unavailable except the output. A nonlinear observer is constructed to estimate the unmeasurable states. Then, based on the constructed observer and a tan-type barrier Lyapunov function (BLF), an adaptive fuzzy output-feedback control strategy is developed by combining the technique of adding a power integrator with the fuzzy logic systems (FLSs). The proposed scheme enables that all the signals of the considered closed-loop systems are bounded in probability while the prespecified output constraint is not violated. Finally, a numerical example verifies the validation of the proposed scheme. [ABSTRACT FROM AUTHOR]

To avoid the bumps of the control signal in the switching instants, this paper proposes a bumpless transfer control method which guarantees the continuous of control signal while keeping the asymptotic stability of the closed-loop system. Firstly, the presented bumpless transfer control method possesses a simple structure and meanwhile not have to redesign sub-controllers, which is easy to implement. Furthermore, the method is appropriate for either stable subsystems or unstable subsystems, and be suitable for either state feedback control or dynamic output feedback control. Moreover, we give the sufficient conditions of asymptotic stability for switched linear systems under bumpless transfer control for four cases. For the original switched system with stable subsystems under state or dynamic output feedback control, the stability conditions under mode-dependent average dwell time switching are derived. For the original switched system with unstable subsystems under state or dynamic output feedback control, which is stabilized by some certain switching laws, the stability conditions under the original switching law are given. Finally, a hardware-in-the-loop simulation of an aero-engine control system is employed to verify the effectiveness and superiority of the proposed method. [ABSTRACT FROM AUTHOR]

This paper presents a time-division-multiplexed (TDM) clocked-analog low-dropout regulator (CLDO) that shares one controller between multiple output channels. Clocked-analog operation is introduced to create idle periods that enable the shared controller to independently regulate different output channels through time-division multiplexing. Furthermore, an asynchronous transient enhancing technique is presented. Thanks to the controller sharing, the TDM CLDO is more area-efficient than conventional designs for supplying multiple outputs, especially when power stages and on-chip loads are small. To verify the effectiveness of the TDM CLDO, a dual-channel version is fabricated in a 130 nm CMOS process. Measurement results show that it can independently track two 100 kHz $0.3~\rm V_{pp}$ sinusoidal signals with 4 mV average output error at $100~\Omega $ load and 6 MHz clock frequency. For load transient responses, it can independently regulate two output channels to 1.05 V and 0.95 V with 41 mV/88 mV and 67 mV/39 mV overshoot/undershoot when both channels experience 5 mA current steps at $1.2~\rm V_{dd}$. To the best of our knowledge, this is the first time that hardware sharing is implemented for continuous closed-loop systems. [ABSTRACT FROM AUTHOR]

This paper studies the problems of global and semi-global stabilization of discrete-time linear systems with multiple input saturations and arbitrarily large bounded delays. By developing the methodology of truncated predictor feedback (TPF), state feedback control laws using only the current states of the systems are constructed to solve these problems. The feedback gains are dependent on the delay information of the open-loop system and thus are referred to as delay-dependent feedback. A method for determining the exact condition such that the resulting closed-loop system is asymptotically stable is also presented. Moreover, if the delays in the system are time-varying or even unknown, a modified delay-independent TPF is also established to solve the concerned problems. Numerical example has been worked out to illustrate the effectiveness of the proposed approaches. [ABSTRACT FROM AUTHOR]

This paper investigates the problem of dynamic event-triggered output feedback tracking control for a class of $p$ -normal nonlinear systems with unknown growth rate. To cope with the unknown growth rate imposed on the system nonlinearities, a dynamic gain technique is introduced and a constructive coordinate transformation is given. On the other hand, an event-triggered strategy combining with the dynamic gain is proposed such that the triggering threshold can be adjusted in an adaptive manner. With the help of the proposed event-triggered strategy, a dynamic event-based output feedback controller is developed to ensure that all signals of the closed-loop system are bounded while the tracking error converges to a small neighborhood of the origin. Moreover, it is proved that the Zeno behavior is excluded in the presence of nonsmooth controller. Two examples, including an induction heater circuit system and a numerical example, are provided to indicate the effectiveness of the proposed control method. [ABSTRACT FROM AUTHOR]

This paper is concerned with global stabilization of discrete-time multiple integrators with bounded controls by utilizing the energy function based approach. First, a discrete-time double integrators system subject to input additive disturbances is stabilized by a bounded feedback whose formula involves a linear function of the state and a saturation function only. Next, this result is used to stabilize a discrete-time multiple integrators of arbitrary length by bounded control with the aid of a special canonical form. Compared with the existing results, the proposed controllers require fewer saturation functions, which allow a better use of the control energy. Moreover, some free parameters that are introduced into these controllers can help improve the transient performance of the closed-loop systems significantly. Finally, a numerical example is given to illustrate the effectiveness of the proposed method. [ABSTRACT FROM AUTHOR]

This paper addresses the problem of event-triggered $\mathcal {H}_{\infty }$ control for continuous Takagi-Sugeno fuzzy systems with repeated scalar nonlinearities. A feasible stability solution is first proposed based on the fuzzy-rule-dependent Lyapunov functional methods and positive definite diagonally dominant matrix techniques, which not only reduces the conservativeness of the resulting closed-loop dynamic system, but also ensures the concerned fuzzy system is asymptotically stable with a specified $\mathcal {H}_{\infty }$ disturbance attenuation performance. Then, sufficient conditions are presented for the existence of admissible state-feedback controller, and the cone complementarity linearization approach is employed to convert the non-convex feasibility problem into a sequential minimization one subject to linear matrix inequalities, which can be validly solved by employing standard numerical software. In the end, a numerical example and a Chua’s chaotic circuit system are provided to show the applicability of the proposed theories. [ABSTRACT FROM AUTHOR]

This paper investigates the adaptive fuzzy output feedback event-triggered control problem for a class of switched nonlinear systems with sensor faults. Due to that the unknown nonlinearities of the systems are more general and the sensor undergoes faults, the considered problem is difficult to be addressed by existing schemes. Therefore, fuzzy logic systems are employed to approximate unknown nonlinear terms and a fault compensation coefficient is introduced to compensate for the effect of sensor failures. Then, a state observer is established for estimating unmeasured states. By choosing a suitable common Lyapunov function, an adaptive fuzzy output feedback fault-tolerant event-triggered controller is derived. It is proven that the proposed scheme can guarantee that the system output tracks the desired trajectory effectively, all states of the resulting closed-loop system are semi-globally uniformly ultimately bounded, and the Zeno phenomenon is excluded. Finally, two simulation examples, which include a switched RLC circuit system and a numerical example, are presented to show the the effectiveness of the proposed strategy. [ABSTRACT FROM AUTHOR]

This paper investigates the event-based control for network systems. Edge-based approach is utilized to predict the value of edge state between two event instants. Different from the node-based approach, it can significantly reduce the communication burden at event instants. Based on the small gain theorem, the closed-loop system is expressed as the feedback interconnection of a linear time-invariant system and an operator. The operator describes the unstable component and has an upper bound in L2 space and the control gain is designed, such that the feedback interconnection is stable. Furthermore, we adopt the integral quadratic constraints to describe the correlation between output and input of the operator. And the Kalman–Yakubovich–Popov Lemma is adopted to transform the infinite dimensional stability condition into one inequality. The designed event-triggering condition and distributed control law can ensure that a network system achieves synchronization. The effectiveness of the communication protocol and control strategy is illustrated by a numerical example. [ABSTRACT FROM AUTHOR]

The output voltage regulation problem of a PWM-based dc-dc buck converter under various sources of uncertainties and disturbances is investigated in this paper via an optimized active disturbance rejection control (ADRC) approach. Aiming to practical implementation, a new reduced-order generalized proportional integral (GPI) observer is first designed to estimate the lumped (possibly time-varying) disturbances within the dc-dc circuit. By integrating the disturbance estimation information raised by the reduced-order GPI observer into the output prediction, an optimized ADRC method is developed to achieve optimized tracking performance even in the presence of disturbances and uncertainties. It is shown that the proposed controller will guarantee the rigorous stability of the closed-loop system, for any bounded uncertainties of the circuit, by appropriately choosing the observer gains and the bandwidth factor. Experimental results illustrate that the proposed control solution is characterized by improved robustness performance against various disturbances and uncertainties compared with traditional ADRC and integral model predictive control (MPC) approaches. [ABSTRACT FROM PUBLISHER]

Energy harvesting is an emerging technology for powering wireless sensor nodes, enabling battery-free operation of these devices. In an energy harvesting sensor, a power management circuit is required to regulate the variable harvested voltage to provide a constant supply rail for the sensor circuits. The power management circuit needs to be compact, efficient, and robust to the variations of the input voltage and load current. A closed-form power expression and custom control algorithm for regulation of a switched-capacitor DC-DC converter with optimal conversion efficiency are proposed in this paper. The proposed regulation algorithm automatically adjusts both the voltage gain and switching frequency of a switched-capacitor DC-DC converter based on its input voltage and load current, increasing the power efficiency across a wide input voltage range. The design and simulation of a fully integrated circuit based on the proposed power managing approach is presented. This power management circuit has been simulated in a 0.25 \mum standard CMOS process and simulation results confirm that with an input voltage ranging from 0.5 V to 2.5 V, the converter can generate a regulated 1.2 V output rail and deliver a maximum load current of 100 \muA. The power conversion efficiency is higher than 74% across a wide range of the input voltage with a maximum efficiency of 83%. [ABSTRACT FROM AUTHOR]

This paper deals with the joint optimization problem of high-order error-feedback and realization for minimizing roundoff noise at the output of a closed-loop system with a full-order observer feedback system subject to l2-scaling constraints. It is shown that the problem can be converted into an unconstrained optimization problem by using linear-algebraic techniques. The unconstrained optimization problem at hand is then solved iteratively by employing an efficient quasi-Newton algorithm with closed-form formulas for key gradient evaluation. A case study is presented to demonstrate the validity and effectiveness of the proposed technique. [ABSTRACT FROM AUTHOR]

In this paper, the proposed topology of a fully automated control (FAC) battery charger that provides turbo-boost operation and fully automated detection without any feedback from the system is discussed. It uses closed-loop control for automatic system load detection and automatically adjusts the battery discharge current. The advantages include shortened battery discharge time and maximum power provided by the adapter. Therefore, the FAC technique is flexible for any load system that is limited to battery chargers with the turbo boost mode support. In addition, to avoid over discharge, a battery protection circuitry is also included. The test chip is fabricated using a 0.25- $\mu \text{m}$ CMOS process, with a maximum efficiency of 94.58% when the charger operates in the turbo boost mode, and achieves 97% maximum efficiency when the charger operates in buck charge mode. [ABSTRACT FROM AUTHOR]

This paper deals with nonlinear control of a single-phase half-bridge interleaved buck shunt active power filter (HBIB-SAPF) with a nonlinear load. The control objective for the system is twofold: performing power factor correction by compensating for harmonics and reactive current consumed by the nonlinear load from one hand and tightly regulating the HBIB converter DC capacitor voltage. Both objectives are accomplished using a two-loop nonlinear controller. The inner loop acts on the switching devices so that the active filter current tracks its reference with the aim of ensuring a unity power factor. This loop is tackled using backstepping technique and Lyapunov approach. The outer loop is responsible for regulating the DC capacitor voltage to its desired value, using a PI controller with a pre-filter. The stability analysis of the closed-loop system is formally performed by using the averaging theory. The validity of the designed nonlinear controller is checked by simulations in Matlab/SimpowerSystem showing its robustness and accuracy under various operating conditions. [ABSTRACT FROM AUTHOR]

This paper considers the problem of finite-time synchronization for a class of second-order nonlinear multi-agent systems with a leader-follower architecture. By using the finite-time control technique and homogenous systems theory, a finite-time state feedback controller is first proposed. Then to address the lack of velocity measurement, a finite-time convergent observer is constructed to estimate the unknown velocity information in a finite time. Finally, an observer-based finite-time output feedback controller is developed. Rigorous proof shows that the systems output can reach synchronization in a finite time and the final consensus states are the leader's states. In addition, for some special second-order multi-agent systems, a bounded finite-time output feedback controller can also be designed. [ABSTRACT FROM AUTHOR]

A low-noise high-linearity switched capacitor interface implemented in a 0.35 \mu \text m 3.3 V/15 V CMOS process is presented in this paper for a ±50g capacitive micro-accelerometer. The sensing element is enclosed in an optimized closed loop with proportional-integral compensation, improving the linearity significantly. In order to suppress the flicker noise of the front-end at the lowest cost, a novel switched capacitor PI controller combined with a charge sensitive amplifier using correlated double sampling is proposed. Furthermore, a detailed noise analysis of the proposed CSA-PIC combination with a final goal of achieving 120 dB dynamic range is also presented. The theoretical analysis is verified by the consistency between calculated results and PNoise simulation results. The sensor output can be read in analogue domain from a sample-and-hold buffer or in digital domain from a back-end 2–1 MASH $\Sigma$ - \Delta$ ADC. The fabricated prototype circuit measures 11.75 mm2 and operates under 15-V and 3.3-V supplies at a sampling clock of 111 KHz. Meanwhile, a sensitivity of 99.7 mV/g is achieved with a dynamic range of 112.4 dB over a 200-Hz bandwidth. The accelerometer has a DC nonlinearity of 0.623 in the range of −18 g to +14 g measured in self-test mode and the bias instability is 200 \mu \text {g} . [ABSTRACT FROM AUTHOR]

This paper investigates the problem of sensor fault estimation and fault-tolerant control for Markovian jump systems with time delay and Lipschitz nonlinearities. The issues involved here are: i) sensor faults; ii) model Lipchitz nonlinearities; iii) system structure changes governed by Markovian jumping parameters; and iv) time delay in system states. Such type of mathematical models can represent a large number of practical systems in the actual engineering. A new estimation technique (named proportional and derivative sliding mode observer) is developed to deal with this design problem. The proposed observer is mode-dependent type in which a derivative gain and a proportional gain are introduced to provide more design freedom, and a discontinuous input term is introduced to eliminate the effects of sensor faults. By employing the developed estimation technique, the asymptotic estimations of system states and sensor faults can be obtained simultaneously. Based on the estimation, an observer-based fault-tolerant control scheme is developed to stabilize the resulting closed-loop system. Finally, a numerical example is presented to illustrate the effectiveness and applicability of the proposed technique. [ABSTRACT FROM PUBLISHER]

This paper presents a 220-MHz pulse width modulation (PWM) fully integrated KY dc–dc step-up converter utilizing bondwire as power inductor, with discontinuous conduction mode (DCM) calibration control. We develop the first DCM closed-loop PWM controller for the KY converter, including: 1) its parameter design; 2) a DCM closed-loop voltage mode control with Type II compensator; 3) a zero current detection method to activate DCM control; and 4) a DCM calibration loop. Fabricated in 65-nm CMOS, the designed KY converter core occupies 0.93 mm2 and achieves an output conversion range of 1.5–2 V from a 1.2-V input. The measured peak efficiency is 75.2% at 97.5 mW. With a 500-ps rising/falling time of the load current step (56 mA), the undershoot/overshoot is 245/205 mV at 146-/140-ns recovery time, and the dc–dc converter achieves a settling time per load transient step of 2.6 ns/mA, which is competitive with the state-of-the-art boost converters. [ABSTRACT FROM AUTHOR]

This paper proposes a flexible dual-mode soft-output multiple-input multiple-output (MIMO) detector to support open-loop and closed-loop in Chinese enhanced ultra high throughput (EUHT) wireless local area network (LAN) standard. The proposed detector uses minimum mean square error (MMSE) sorted QR decomposition (MMSE-SQRD) to produce channel preprocessing result, which is realized by a modified systolic array architecture with concurrent sorting. Moreover, the adopted square-root MMSE algorithm for closed-loop reuses MMSE-SQRD preprocessing to largely save hardware overhead. In addition, an optimized K-Best detection algorithm is proposed for open-loop, which increases throughput by odd-even parallel sorting and produces high quality soft-output with discarded paths (DPs). A flexible VLSI architecture is designed for the proposed dual-mode detector, which supports 1\times 1\sim 4\times 4 antennas and BPSK \sim 64-QAM modulation configuration. Implemented in SMIC 65 nm CMOS technology, the detector is capable of running at 550 MHz, which has a maximum throughput of 2.64 Gb/s for K-Best detection and 3.3 Gb/s for linear MMSE detection. The proposed detector is competitive to recent published works and meets the data-rate requirement of the EUHT standard. [ABSTRACT FROM PUBLISHER]

This paper introduces a new and unified approach for designing desirable dissipative hyperchaotic systems. Based on the anti-control principle of continuous-time systems, a nominal system of n ~~(n \geq 5) independent first-order linear differential equations are coupled through all state variables, making the controlled system be in a closed-loop cascade-coupling form, where each equation contains only two state variables therefore the system is quite simple. Based on this setting, a simple model for dissipative hyperchaotic systems is constructed, with an adjustable parameter which can ensure the dissipation of the system. In the closed-loop cascade-coupling form, it is shown that all the eigenvalues are symmetrically distributed in a circumferential manner. Consequently, a universal law is derived on the relationship of the number of positive Lyapunov exponents and the number of positive real parts of its Jacobian eigenvalues. For the above-mentioned simple model, the number of positive Lyapunov exponents for any n-dimensional dissipative hyperchaotic system is given by N= round((n-1)/2), n \geq 5. Therefore, in theory, the system can generate any desired number of positive Lyapunov exponents as long as the dimension of the system is sufficiently high. Thus, the proposed method provides a new approach for purposefully constructing desirable dissipative hyperchaotic systems. Finally, two examples are given to demonstrate the feasibility of the proposed design method. [ABSTRACT FROM AUTHOR]

Aimed at the problem that the unmanned aerial vehicle (UAV) close formation cannot maintain its desired formation shape due to the wind field disturbances, a novel distributed adaptive control approach is proposed to counteract the lateral and forward distance errors caused by uncertain wind field disturbances. Firstly, based on the “leader-follower” model, an adaptive control law is designed to accurately estimate the magnitude and direction of the wind in 3-D space. Then, the distance errors caused by uncertain wind field disturbances is counteracted by controlling UAV relative movement. Moreover, their velocity can keep constant to achieve the desired formation shape. Additionally, the signals of the closed-loop system are semi-globally practical finite-time stable (SGPFS). Finally, the simulation results show that the proposed adaptive control algorithm has good robustness, which provides a theoretical basis for engineering practice. [ABSTRACT FROM AUTHOR]

While a host of analysis techniques exist to perform steady-state analysis of open-loop converter systems, solutions for close-loop converter systems are distinctly more challenging to obtain. Analysis is done either via computationally intensive time-domain simulation or through reliance on a disconnected collection of published iteration techniques. Moreover, most of these iteration techniques deal with a system containing only one or two converters. This is not adequate to deal with a smart grid or microgrid system, which consists of multiple (more than two) converters. This paper proposes a generalized and systematic solution procedure to obtain the steady state of a system containing multiple closed-loop power converters, in a computationally efficient manner. The solution procedure consists of a general five step approach that can easily be applied to a wide variety of power converter systems. It is shown that numerous previously proposed methods may be viewed as specific implementations of the generalized systematic procedure. A new solution approach, suitable for analysis of tightly coupled multiconverter networks, is developed based on the generalized solution procedure. Results of the new approach are validated against PSCAD/EMTDC simulations for a representative multiconverter network. [ABSTRACT FROM PUBLISHER]

By considering the under-actuated characteristics of the quadcopter suspension transportation system and the external disturbance, the effective tracking control of the quadrotor transportation system faces great difficulties and challenges. An adaptive hierarchical sliding mode control (HSMC) scheme based on fixed-time sliding mode disturbance observer (FTSMDO) is developed for the anti-disturbance tracking control of under-actuated quadcopter suspension transportation system (UQSTS). The HSMC is used to deal with the under-actuated characteristics of the UQSTS, and the external disturbance is estimated by designing the FTSMDO. Synchronously, the disturbance estimation error is processed by designing the adaptive law. The stability analysis based on Lyapunov is applied to verify the uniform ultimate boundedness of the closed-loop system. Finally, the comparison of physical experiment upshots shows the effectiveness and potential of the proposed new control techniques. [ABSTRACT FROM AUTHOR]

Steady-state optimization and real-time controls are conventionally achieved by separate controllers acting at different timescales in dc microgrids. The separation between them not only lowers the overall energy efficiency but also can cause the line currents and the output currents of distributed generators (DGs) to exceed their limits. Targeting these issues, an optimal controller for dc microgrids is proposed in this article to simultaneously achieve the real-time minimization of operating losses (converter losses and line losses) and the regulation of line currents and DG output currents. First, the optimization problem is established, then converted to an optimal control problem by a designed penalty function. Thereafter, the necessary and sufficient optimality conditions of the problem are derived, based on which a distributed controller is proposed to dynamically track the optimal operating point. Driven by the proposed optimal controller in real-time, line current and DG output current regulations are ensured with greatly enhanced performance. Finally, the closed-loop system stability is analyzed rigorously through Lyapunov stability synthesis. Simulations based on a switch-level microgrid model validate the performance of the proposed control solution. [ABSTRACT FROM AUTHOR]

The development of systems-on-chip requires embedded power management solutions due to the large number of power domains. The switched-capacitor voltage regulator is a suitable candidate as capacitors may be integrated whereas inductors still suffer limitations in that respect. Literature covers proposals of optimized power stages and several dedicated controllers for switched-capacitor DC-DC converters. Unfortunately the results do not cover systematic stability analyses. The paper proposes an original and systematic approach for the stability analysis of a switched-capacitor voltage regulator using sampled-data modeling. An application is given for a one-phase converter with a frequency-modulation based controller. The stability of the open-loop and closed-loop model is proposed and can be extended to multi-phase configurations. [ABSTRACT FROM AUTHOR]

We study the problem of controlled network synchronization for a class of identical linear systems. The systems are interconnected through static and dynamic diffusive couplings with time-delays. In particular, we derive conditions on the systems, on the couplings, on the time-delay, and on the network topology that guarantee global synchronization of the systems. Diffusive time-delayed dynamic couplings are constructed by combining linear observers and output feedback controllers. Using passivity properties, sufficient conditions for boundedness of the interconnected systems are derived. Moreover, predictor-based dynamic couplings are proposed in order to enhance robustness against time-delays in the network. The results are illustrated by numerical simulations. [ABSTRACT FROM AUTHOR]

This note considers the issue of global asymptotic stabilization for a class of nonlinear systems with unknown time-varying delays and control gain using a dynamic event-triggered (DET) output feedback scheme. In the context of unknown time-varying delays and control gain, nonsmooth control law and some extra redundant terms will be encountered in the design of DET controller, which would bring substantial challenges to the achievement of event-triggered stabilization. Specifically, two dynamic gains and a modified Lyapunov-Krasovskii functional are first presented, which makes the effects of time-varying delays and control gain be conquered. Then, a DET mechanism utilizing the dynamic gain is given to reduce the amounts of event transmissions and dynamically compensate the triggering error. By virtue of the designed strategy, a new DET output feedback controller is developed, which renders the closed-loop system globally asymptotically stable. Meanwhile, it is proved that the Zeno behavior does not happen. Finally, in order to demonstrate the feasibility of the proposed scheme, corresponding examples are provided. [ABSTRACT FROM AUTHOR]

In this article, the sliding mode control (SMC) design is studied for a class of stochastic switching systems subject to semi-Markov process via an adaptive event-triggered mechanism. Network-induced communication constraints, semi-Markov switching parameters, and uncertain parameters are considered in a unified framework for the SMC design. Due to the constraint of measuring transducers, the system states always appear with unmeasurable characteristic. Compared with the traditional event-triggered mechanism, the adaptive event-triggered mechanism can effectively reduce the number of triggering than the static event-triggered mechanism. During the data transmission of network communication systems, network-induced delays are characterized from the event trigger to the zero-order holder. The aim of this work is to design an appropriate SMC law based on an adaptive event-triggered communication scheme such that the resulting closed-loop system could realize stochastic stability and reduce communication burden. By introducing the stochastic semi-Markov Lyapunov functional, sojourn-time-dependent sufficient conditions are established for stochastic stability. Then, a suitable SMC law is designed such that the system state can be driven onto the specified sliding surface in a finite-time region. Finally, the simulation study on boost converter circuit model (BCCM) illustrates the effectiveness of the theoretical findings. [ABSTRACT FROM AUTHOR]

In this study, a class of finite-time consensus of multiple transmission control protocol/active queue management (TCP/AQM) networks is investigated on the basis of a design idea of multi-agent systems, and for the first time, to our knowledge, a novel congestion control concept with neural networks is proposed. First, the problem statement and design goal of the consensus of multiple TCP/AQM networks is given. Then, a pre-assigned finite-time function is introduced to ensure that the tracking error approaches a pre-defined area within finite time. Furthermore, by combining a barrier Lyapunov function and backstepping technique, a neural network-based distributed adaptive finite-time control protocol for the output consensus of multiple TCP/AQM networks is presented, which can effectively generate the desired controls and ensure that the convergent time of all errors has nothing to do with the initial condition and design parameters. In addition, all signals in the closed-loop system are bounded. Finally, an example is given to further illustrate the effectiveness of the theoretical finding presented. [ABSTRACT FROM AUTHOR]

The problem of decentralized event-triggered control for a class of network-based state-dependent uncertain systems subject to network transmission delay and deception attacks is considered in this article. To reduce network load, a novel decentralized adaptive event-triggered scheme (AETS) is developed to transmit necessary sampled signals. During network transmission, a more practical deception attack phenomenon is considered, where the attack behaviors in different channels are governed by independent Bernoulli processes. Moreover, a set of improved data buffers are applied in the controller side to organize the decentralized triggered data and alleviate the impact of network transmission delay, such that the transmitted data can be utilized timely. Then, an integrated closed-loop system with state-dependent uncertainties is constructed by taking the AETS, deception attacks and data buffers into account. Sufficient conditions that guarantee the mean-square exponential stability of the closed-loop system are presented by employing the Lyapunov functional method, and the design criterion of the controller gain is given by an exact expression. Finally, the proposed method is applied to the control of electronic circuits to verify its practicability and effectiveness. [ABSTRACT FROM AUTHOR]

The globally finite-time control issue is concerned in this note for high-order nonlinearly parameterized systems with unknown control gain and external disturbances. A novel control strategy combining adaptive control technique with sign function can well deal with serious uncertainties and unknown control gain. Without any nonlinear growth assumptions, a unified and systematic design procedure is employed to derive an adaptive state-feedback controller with the help of the adding a power integrator method and backstepping technique. Then, by finite-time stability analysis and Lyapunov functions, the proposed controller ensures that the closed-loop system is globally practically finite-time stable (PFTS). Two simulation examples, including a mass-spring mechanical system and a numerical example, are applied to verify the performance and effectiveness of the designed schemes. [ABSTRACT FROM AUTHOR]

A time-invariant multi-frequency modeling technique is proposed for pulse-width-modulated (PWM) dc-dc converters. The proposed methodology distinguishes between different types of modulation carrier signals (e.g., sawtooth and isosceles triangle carriers). A straightforward systematic procedure is proposed to automatically convert the conventional state-space time-variant model to the proposed time-invariant model. Hence, high-order time-invariant models can be easily developed for system design and stability analysis purposes. Closed-loop time-domain and open-loop frequency-domain responses extracted from a laboratory-scale Cuk converter have verified the proposed methodology. [ABSTRACT FROM PUBLISHER]

This work addresses the design of state feedback controllers for locally stabilizing open-loop unstable quadratic systems with guaranteed stability domain and performance. First, a method is derived to design a stabilizing nonlinear static state feedback controller, which is quadratic in the system state, while providing an enlarged stability region for the closed-loop system. The stabilization method is then extended in three directions. The first one is to ensure a quadratic regulator-type performance, the second is the local stabilization, in sense of integral input-to-state stability, of quadratic systems disturbed by energy-bounded exogenous signals, whereas the third extension provides a solution to the H∞ control problem. The developed control methods are tailored via finite sets of state-dependent linear matrix inequalities. Several numerical examples are presented to illustrate the potentials of the proposed controller designs. [ABSTRACT FROM PUBLISHER]

A fully integrated 256-Mcell multi-level cell (MLC) phase-change memory (PCM) chip in 90-nm CMOS technology is presented. The on-chip circuitry supports fast MLC operation at 4 bit/cell. A programmable digital controller is used to optimize closed-loop gain and timing of the iterative MLC programming scheme and two power-efficient 8-bit DACs support current-controlled as well as voltage-controlled write pulses. The read-out consists of a low-power auto-range frontend followed by a 6-bit cyclic ADC that converts the nonlinear PCM resistance in a range between 10 k\Omega and 10 M\Omega. A verilog-A model derived from a full 3-D simulation of the PCM cell was developed to simulate the complete chip. The chip was used to demonstrate operation at 2 bit/cell and programming below 10 \mus with Ge2Sb2Te5 (GST) based PCM cells at a raw bit error rate of \sim 2 \times 10^- 4. Two main roadblocks for MLC PCM are drift and endurance. The accuracy of the analog frontend in combination with the programmable controller enables drift mitigation at the system level and the exploration of new materials for MLC operation at 3+ bit/cell. [ABSTRACT FROM PUBLISHER]

The article investigates an adaptive practical fixed-time tracking control of nonlinear systems with prescribed boundary constraints. The main control objective is that the system output variable tracks the desired signal at fixed time, and the tracking error can also converge to the prescribed boundary constraints. Primarily, a new coordinate transformation is introduced, which will be utilized in the proposed controller. Next, based on the backstepping scheme, the sufficient conditions for the existence of the adaptive practical fixed-time tracking controller are presented. Meanwhile, the fuzzy logic systems are employed to approximate to unknown parts in the controlled system. Theoretical analysis shows that the tracking error converges to the prescribed boundary constraints at fixed time. At the same time, all the signals in the closed-loop controlled system are bounded and the controlled system is practically fixed-time stable. At last, simulation results verify the effectiveness of the proposed scheme by comparing the cases with/wihtout prescribed boundary constraints. [ABSTRACT FROM AUTHOR]

This article proposes a fault-tolerant control (FTC) strategy based on virtual actuator and sensor for discrete-time descriptor systems subject to actuator and sensor faults. The fault-tolerant closed-loop system, which includes the nominal controller and observer, as well as the virtual actuator and the virtual sensor, hides the effects of faults. When an observer-based state-feedback law is considered, the existence of algebraic loop may prevent the practical implementation due to the current algebraic states depending on the current control input, that affects also the implementation of the virtual actuator/sensor. To deal with this issue, an observer-based delayed feedback controller and a delayed virtual actuator are proposed for discrete-time descriptor systems. Furthermore, the satisfaction of the separation principle is shown, and an improved admissibility condition is developed for the design of the controller and virtual actuator/sensor. Finally, some simulation results including an electrical circuit are used to demonstrate the applicability of the proposed methods. [ABSTRACT FROM AUTHOR]

Conventional digital signal processor (DSP) based digital controllers are not specifically optimized for multi-rail DC-DC converter applications. A new application-specific instruction-set processor (ASIP) that overcomes the shortcomings of existing controllers has thus been designed, implemented, and evaluated. The proposed dual multiply-accumulate (MAC) architecture has been implemented using a field programmable gate array and verified in a closed-loop power converter system. The benefits of the proposed ASIP are illustrated through a comparison with a conventional single MAC processor architecture. Experimental results demonstrate improved output voltage transient response compared with existing DSP-based controllers when controlling multiple DC-DC converters. In the case of multiple converters that have a non-integer switching frequency ratio more significant improvements in transient response are obtained due to the processor's interrupt controller. [ABSTRACT FROM AUTHOR]