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This article is concerned with the model-based event-triggered sliding-mode control (SMC) issue for multi-input systems, which is motivated by some existing results in a single-input case. A model-based event-triggered SMC scheme is first designed. In particular, a triggered condition is co-designed with SMC to achieve the reachability condition of a specified sliding surface. Thus, it can effectively mitigate the burden of data communication, and also eliminate the effect of the matched external disturbance and the model uncertainties in both system and input. For ensuring the stability of the model dynamics and the resulting sliding-mode dynamics simultaneously, an auxiliary disturbance input is introduced to the nominal model by compensating the switching term of the designed SMC law. Furthermore, the positive lower bound for the minimum interevent time is analyzed to ensure the feasibility of the proposed approach. To illustrate the proposed model-based event-triggered SMC approach from a practical viewpoint, two design problems to maximize the system robustness and performance are proposed, respectively. The nontrivial optimization problems are then solved by a genetic algorithm (GA). Finally, jet transport aircraft is utilized to demonstrate the effectiveness of the proposed results and algorithm. [ABSTRACT FROM AUTHOR]

This brief investigates the sliding mode control (SMC) problem of two-dimensional (2D) systems depicted by the Roesser model subject to limited communication channels. The stochastic communication protocol is employed to schedule the transmission from controller to actuators, under which only one controller node at each instant will be randomly selected to transmit its signal. To maintain the structural characteristics of 2D system, a sliding surface related to the horizontal and vertical states is constructed. By introducing the zero-input strategy to generate the information of unchosen nodes, a token-dependent SMC is designed, and both the reachability of the sliding surface and the asymptotic stability of the closed-loop system are analyzed. Moreover, the feasible SMC is obtained via solving a minimization problem. Finally, the proposed control scheme is applied in the metal rolling process. [ABSTRACT FROM AUTHOR]

This article is concerned with the design of a super-twisting algorithm (STA) based sliding mode controller for permanent magnet synchronous motor (PMSM) speed regulation system under the self-triggered mechanism. By using the strict Lyapunov function approach, it is shown that the tracking error converges to an ultimate domain within the finite-time sense under the proposed self-triggered STA. A feasible self-triggered strategy is designed for both cases with and without external perturbation. Moreover, a nonlinear optimization problem is formulated in terms of the tradeoff between the ultimate domain and the communication burden. The optimized STA gains are obtained by solving the above-formulated optimization problem via a particle swarm optimization algorithm. Finally, the applicability of the proposed self-triggered STA for PMSM is verified by simulation and experiment results. [ABSTRACT FROM AUTHOR]

The co-design problem of 2-D event generators and sliding mode controller (SMC) is studied in this article for the discrete-time 2-D Roesser model to reduce the communication usage between the plant and the controller. First, by resorting to the 2-D reaching law conditions, the event-based 2-D SMC schemes are proposed and a kind of horizonal/vertical independent event generator is designed. Then, the stability of the sliding-mode dynamics is analyzed and a nonlinear matrix inequality condition associated with the horizontal/vertical sliding matrices is obtained. In order to solve the derived nonlinear matrix inequality condition without introducing conservatism, a binary genetic algorithm (GA) is applied by considering a multiobjective optimization problem, which reflects the tradeoff between the convergence of the sliding-mode dynamics and the scheduling performance of the designed horizontal/vertical event generators. Finally, a simulation example is exploited to demonstrate the effectiveness of the proposed co-design approach with GA. [ABSTRACT FROM AUTHOR]

The sliding-mode control (SMC) problem is studied in this article for state-saturated systems over a class of time-varying fading channels. The underlying fading channels, whose channel fading amplitudes (characterized by the expectation and variance) are allowed to be different, are modeled as a finite-state Markov process. A key feature of the problem addressed is to use a hidden Markov mode detector to estimate the actual network mode. The novel model of hidden Markov fading channels (HMFCs) is shown to be more general yet practical than the existing fading channel models. Based on a linear sliding surface, a switching-type SMC law is dedicatedly constructed by just using the estimated network mode. By exploiting the concept of stochastic Lyapunov stability and the approach of hidden Markov models, sufficient conditions are obtained for the resultant SMC systems that ensure both the mean-square stability and the reachability with a sliding region. With the aid of the Hadamard product, a binary genetic algorithm (GA) is developed to solve the proposed SMC design problem subject to some nonconvex constraints induced by the state saturations and the fading channels, where the proposed GA is based on the objective function for optimal reachability. Finally, a numerical example is employed to verify the proposed GA-assisted SMC scheme over the HMFCs. [ABSTRACT FROM AUTHOR]

This article addresses the security control problem of a class of interval type-2 fuzzy systems via the sliding mode control strategy. A stochastic communication scheduling protocol is utilized to govern the transmission from the sensors to the controller, by which only one sensor node has the chance to transmit its value at every instant. Meanwhile, cyber attacks from malicious adversaries might be launched in vulnerable communication channels. To quantitatively analyze the effect of the stochastic communication protocol and cyber attacks, their mathematical model is first constructed based on a compensation scheme. Since the scheduling signal may be unavailable once cyber attacks are activated, a desirable sliding mode control law is synthesized with token-independent control gains, whose membership functions are mismatched with those of the fuzzy system. To deal with these mismatched membership functions, the relations between the membership functions of the system and the control law are reconstructed. Consequently, the favorable property of perfectly matched memberships could be employed. Sufficient conditions are derived so that the resultant closed-loop interval type-2 fuzzy system is stochastically stable and, at the same time, the state trajectories can be forced into a small domain around the prescribed sliding surface. The proposed control design approach is verified by two examples. [ABSTRACT FROM AUTHOR]

We design and integrate four optical phased arrays (OPAs) in a single chip. Each OPA possesses different output grating period. Furthermore, we use optical switches to select one or more OPAs for beam scanning. We demonstrate the longitudinal scanning by tuning the laser wavelength. The experimental results show that the scanning range of the four-lines chip reaches 28.54° when the wavelength ranges from 1520 nm to 1570 nm, and the eight-lines one reaches 19.04° with wavelength range of 1520 nm-1540 nm. We greatly improve the wavelength tuning efficiency for longitudinal scanning. [ABSTRACT FROM AUTHOR]

This brief endeavors to investigate the sliding mode control (SMC) issue of the networked singularly perturbed systems (SPSs) under slow sampling. For the energy saving purpose in network communication, a dynamic event-triggered mechanism is introduced to SMC design. By considering the structure characteristics of the controlled system, a novel sliding function is constructed with taking the singular perturbed matrix $E_\varepsilon $ into account properly. With the aid of some appropriate Lyapunov functionals, the sufficient conditions are derived to ensure the asymptotic stability of the sliding mode dynamics and the reachability of the specified sliding surface. Besides, it is shown that the quasi-sliding motion is dependent on the dynamic event-triggered parameters and its bound converges to a constant. The solving algorithm for the dynamic event-triggered SMC law is formulated in a convex optimization framework. Finally, an numerical example is provided to illustrate the effectiveness of the proposed results. [ABSTRACT FROM AUTHOR]

The asynchronous sliding mode control (SMC) problem is investigated for networked Markovian jump Lur’e systems, in which the information of system modes is unavailable to the sliding mode controller but could be estimated by a mode detector via a hidden Markov model (HMM). In order to mitigate the burden of data communication, an event-triggered protocol is proposed to determine whether the system state should be released to the controller at certain time-point according to a specific triggering condition. By constructing a novel common sliding surface, this paper designs an event-triggered asynchronous SMC law, which just depends on the hidden mode information. A combination of the stochastic Lur’e-type Lyapunov functional and the HMM approach is exploited to establish the sufficient conditions of the mean square stability with a prescribed ${H}_{\infty }$ performance and the reachability of a sliding region around the specified sliding surface. Moreover, the solving algorithm for the control gain matrices is given via a convex optimization problem. Finally, an example from the dc motor device system is provided. [ABSTRACT FROM AUTHOR]

The lack of high-resolution digital elevation model (DEM) data presents one major limitation for deformation mapping using synthetic aperture radar interferometry (InSAR) techniques with high-spatial-resolution radar imagery (e.g., TerraSAR-X). This article presents a baseline linear combination (BLC) approach to generate interferograms with nearly zero baselines so as to minimize the effects of the uncertainties in the DEM used. It incorporates the baseline combination (BC) method with adjacent gradient networking to successfully unwrap the interferograms even in abruptly discontinuous areas, which in turn can be used to estimate a high-resolution DEM. The BLC approach does not require any deformation model; instead, it utilizes nearly zero-baseline interferograms to assist with 3-D phase unwrapping. Application of the BLC approach to the TerraSAR-X data set in Shenzhen, China, shows that the BLC-derived DEM agrees with the digital surface model (DSM) obtained from light detection and ranging (LiDAR) with a correlation coefficient of 0.998 and a root-mean-square error (RMSE) of 2.05 m, demonstrating the effectiveness of the BLC approach. Note that the BLC approach is not only able to be employed in urban areas with high buildings but also in mountain areas with steep slopes. [ABSTRACT FROM AUTHOR]

A 1.1-V 6.4-Gb/s/pin 16-Gbit DDR5 is presented in 10-nm class CMOS technology. Various functions and circuits’ techniques are newly adopted to improve performance and power consumption compared with DDR4 SDRAM. First, to realize two times higher speed than DDR4, the injection-locked oscillator (ILO) delay locked loop (DLL) is adopted for the low jitter high-speed performance. The proposed DLL with phase rotator (PR) and ILO allows to minimize the clock tree of DRAM, lowering skew and jitter in the DRAM internal clock path. Second, for the high-speed write operation, DQS gate opening control and write leveling are very important to minimize the turnaround time of DRAM, and thus new sequence and logic for the write-level training are introduced in this article. Third, to maximize the data valid window of read DQs, duty cycle adjustable serialize circuit methods are proposed. Finally, to improve the interface speed, the decision feedback equalization (DFE) and feedforward equalization (FFE) are adopted to Rx and Tx, respectively. By implementing all the items mentioned earlier, the 1.1-V 6.4-Gb/s/pin 16-Gbit DDR5 achieved 6.4-Gb/s/pin performance at 1.05-V $V_{DD}$ , with its power bandwidth efficiency 30% higher than that of DDR4. [ABSTRACT FROM AUTHOR]

This paper focuses on the sliding mode control (SMC) problem of interval type-2 (IT2) fuzzy systems subject to the unmeasurable state and cyberattacks. A key issue is how to design a state observer under the constraint that only the bounds of membership functions are known. To this end, this paper introduces two weighting factors to construct a new membership function. Besides, the concept of input-to-state stability (ISS) is utilized to deal with the residual term resulting from the cyberattacks and external disturbances. The sufficient condition is established such that the sliding mode dynamics and the estimated error dynamics are input-to-state stable. Furthermore, by online estimating the unknown parameters in upper bounds of cyberattacks and external disturbances, an adaptive sliding mode controller is synthesized such that the reachability of the prescribed sliding surface can be guaranteed and the effect of cyberattacks on the system performance can be effectively attenuated. Finally, the validity of the proposed method is illustrated by a mass–spring–damper system. [ABSTRACT FROM AUTHOR]