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This article discusses the finite‐time boundedness (FTB) issue and L2$$ {L}_2 $$‐gain analysis for switched stochastic systems, particularly under the dual influence of DoS attacks and false data injection attacks, by employing a novel event‐triggered mechanism. Different from the moment calculation method, a probability‐based FTB is studied which offers more pertinence. To obtain a less conservative condition of FTB, a switched Lyapunov function is constructed. Additionally, a memory‐based dynamic event‐triggered mechanism is designed to reduce the amounts of triggering and mitigate the state response fluctuations. Based on the incomplete information above, state feedback controllers are devised to satisfy stochastic FTB, ensuring the successful attainment of finite‐time L2$$ {L}_2 $$‐gain. Sufficient conditions are cast into a convex optimization problem by LMIs which can be solved easily. Finally, a compared numerical example and an RLC series circuit are adopted to demonstrate the availability of the theoretical results. [ABSTRACT FROM AUTHOR]

This paper focuses on finite-time boundedness problem of switched linear systems under periodically intermittent control. Sufficient conditions are established to guarantee finite-time boundedness or finite-time stability of switched linear systems under periodically intermittent control. The proof procedures are implemented successfully resorting to piecewise Lyapunov functions. Based on the linear matrix inequality technique, the conditions are casted into a convex optimisation problem and therefore, they can be efficiently handled. The method proposed in this paper is a much potentially useful one in practice because of its economical and efficient nature that is easy to employ. Finally, two examples are given to express the validity and efficiency of the proposed methods. [ABSTRACT FROM AUTHOR]

Finite‐time stabilization (FTS) problem of output‐constrained planar switched systems via output feedback is investigated in this paper. State feedback control laws are constructed in a systematic way by combining the revamped adding a power integrator technique (APIT) with the elaborately designed logarithm‐type barrier Lyapunov function (BLF). By merging the constructed variable‐gain switched observers, finite‐time output‐feedback stabilization, then, is achieved with the output constraint meets too. At the end, simulations are presented to show the effectiveness of the proposed method. [ABSTRACT FROM AUTHOR]

Finite‐time non‐smooth stabilization of cascade output‐constrained switched systems via state feedback is investigated. The cascade switched systems consist of subsystems in general form with zero dynamics and mixed powers taken into account. To deal with the finite‐time stabilization problem of such kind of switched systems, some mild assumptions, input‐to‐state stability property of zero dynamics, an appropriate growth rate assumption on nonlinear terms and some well‐known conditions for small signals, have been imposed on subsystems. Then, state feedback controllers are constructed first by revamping adding a power integrator technique and finite‐time stability analysis of the resultant closed‐loop switched systems are implemented by the deliberately constructed tangent‐type barrier Lyapunov function (Tan$$ {T}_{an} $$‐BLF). Meanwhile, the output constraint of switched systems is also implicitly guaranteed by the Tan$$ {T}_{an} $$‐BLF. Switched systems discussed in this article can encompass almost all p$$ p $$‐normal ones because of the inclusion of zero dynamics, mixed powers, and the homogenous upper bounded assumption on nonlinear terms. And, the method proposed in this article operates in a unified framework to tackle finite‐time stabilization of switched systems because the constructed common Tan$$ {T}_{an} $$‐BLF degenerates into a quadratic function when the output constraint tends to infinity. Simulations are carried out to show the efficiency of the proposed method. [ABSTRACT FROM AUTHOR]

For output-constrained switched systems, uniformly local stabilization problem via state feedback is addressed. A unified tool, a common tangent-type barrier Lyapunov function (Tan-BLF), is developed to deal with the stabilization problem of switched systems and to cope with constraints imposed on system output with or without. Then, combining adding a power integrator technique (APIT) and the developed common barrier Lyapunov function, state-feedback stabilizing laws are designed systematically to make the resultant closed-loop switched systems asymptotically stable while preventing the violation of output constraints. The efficiency of the proposed method is illustrated by numerical results. [ABSTRACT FROM AUTHOR]

This note investigates a unified finite-time output feedback control strategy for a class of planar switched systems with an asymmetric output constraint. A fraction-type asymmetric barrier Lyapunov function (BLF) is constructed firstly. Based on relaxed assumptions on system nonlinearities together with the developed BLF, a set of finite-time state feedback controllers are designed systematically by revamping the technique of adding a power integrator. By incorporating the state controllers with switched reduced-order observers developed delicately, the task of finite-time stabilization for planar switched systems can be realized by the resultant output feedback controllers in consideration of asymmetric output constraints imposed on switched systems simultaneously. The proposed method enjoys the unification property such that it is workable for the scenarios of constrained and unconstrained cases, without the need of changing/redesigning the structures of controllers and observers. Finally, simulation results are presented to verify the proposed scheme. [ABSTRACT FROM AUTHOR]

ABSTRACT In this paper, the adaptive non‐smooth fixed‐time state feedback stabilization problem of output‐constrained switched systems are investigated. In order to well deal with the output constrains and uncertain parameters, a common barrier Lyapunov function which includes a tangent‐type term of the system state and a quadratic term of the uncertain parameter estimation error is constructed. Adaptive fixed‐time state feedback controllers and parameter update laws are designed by virtue of adding a power integrator technique with some mild assumption imposed on the subsystem's nonlinear terms. Simulation results of a numerical example and a two‐tank liquid‐level system presented in this paper explicitly demonstrate the effectiveness of the proposed approach in this paper. Subsystems powers considered in this article only need to be greater than zero, regardless of odd or even numbers, which make the structure of switched systems more general. The proposed method provides us to perform the design of the adaptive fixed‐time stabilizers for switched systems with/without output constraints simultaneously with the same controller structure, which means it has a unified nature. [ABSTRACT FROM AUTHOR]

This article investigates the problem of global output feedback stabilization by using aperiodic-sampled-data control, i.e., event-triggered control, for a class of uncertain nonlinear systems under certain assumptions. By employing the technique of output feedback domination, an observer-based event-triggered output feedback control law is explicitly constructed to guarantee the globally asymptotic stabilization. To avoid the Zeno behavior, a combining mechanism with event-triggered and time-triggered is proposed to ensure that the two consecutive updated time for the sampled-data controller is larger than one positive constant. Finally, it is shown that the problem of global output feedback stabilization for a class of uncertain nonlinear systems is solved via the proposed event-triggered control law. Finally, some comparative simulation examples are given to show the efficiency of the introduced method. [ABSTRACT FROM AUTHOR]

Summary: In the framework of sampled‐data control, finite‐time boundedness (FTB) of switched systems with time‐varying delays is investigated. Sufficient conditions for FTB of switched systems with time‐varying delays via sampled‐data control are proposed. Moreover, considering the relationship between the sampling period and the mode‐dependent average dwell time, switching signals are designed. In addition, finite‐time weighted L2‐gain (FTW‐L2‐gain) of switched systems with time‐varying delays is proposed to measure their disturbance tolerance capacity within a finite‐time interval. Multiple Lyapunov‐Krasovskii functionals are applied to complete subsequent proofs in detail. Simulation results are exemplified to verify the proposed method. [ABSTRACT FROM AUTHOR]

Summary: In this article, we investigate the formation control problem of multiquadrotor aircraft system subject to connectivity preservation and collision avoidance. First, based on the backstepping design method, a novel formation control algorithm is developed to enable multiquadrotor aircraft to move along the desired trajectory while becoming the predefined formation pattern. Meanwhile, the connectivity of the communication network is maintained and the collision among multiquadrotor is avoided. Second, for each quadrotor's desired attitude obtained by the formation controller, an improved finite‐time attitude tracking law is designed to guarantee that the desired attitude can be tracked by the real attitude in a fast finite time. Finally, a numerical example is given to demonstrate the effectiveness of the proposed algorithms. [ABSTRACT FROM AUTHOR]

Summary: In this paper, globally asymptotical stabilization problem for a class of planar switched nonlinear systems with an output constraint via smooth output feedback is investigated. To prevent output constraint violation, a common tangent‐type barrier Lyapunov function (tan‐BLF) is developed. Adding a power integrator approach (APIA) is revamped to systematically design state‐feedback stabilizing control laws incorporating the common tan‐BLF. Then, based on the designed state‐feedback controllers and a constructed common nonlinear observer, smooth output‐feedback controllers, which can make the system output meet the predefined constraint during operation, are proposed to deal with the globally asymptotical stabilization problem of planar switched nonlinear systems under arbitrary switchings. A numerical example is employed to verify the proposed method. [ABSTRACT FROM AUTHOR]

The dynamic model is significant for the analysis of the vibrational characteristics of the wheeled tractor system with implement and front axle hydropneumatic suspension. In this work, the nonlinear stiffness and damping equations are derived first. The dynamic coupling relationship among cabin, three-point hitch structure, and implement are figured out, and the dynamic model of the half agricultural wheeled tractor/implement system is presented considering the effects of three-point hitch structure, passive silent blocks of cabin, and front axle hydropneumatic suspension together. To validate the model, the power spectral densities (PSDs) of the driver seat, cabin, chassis, and implement acquired from numerical simulations are compared with those from experiments, respectively. Under different forward speeds, two groups of results match well. Based on the model, the influences of passive cabin suspension, implement, and front axle hydropneumatic suspension on the dynamical characteristics of the tractor system are investigated. Results indicate that the front axle hydropneumatic suspension will deteriorate the ride comfort of the driver but improve the handing stability. The passive cabin suspension reduces the operational stability while improving much more ride comfort than the front axle hydropneumatic suspension does. The driver's comfortableness will be increased due to implement; meanwhile, handling stability will be compromised. Besides, the impacts of initial nitrogen volume, pressure of accumulators, and orifice diameter of throttle valves on the vibration characteristics of the tractor system are also inspected. [ABSTRACT FROM AUTHOR]

In this paper, finite-time boundedness of a class of neutral type switched systems with time-varying delays is investigated. By virtue of linear matrix inequalities, delay-depended sufficient conditions are given to guarantee switched systems with time-varying delays finite-time bounded. If there is no disturbance, finite-time boundedness degenerates into finite-time stability, which is also discussed in this note. Mode-depended average dwell time (MDADT) of switching signals is also given such that neutral type switched systems are finite-time bounded or finite-time stable. Moreover, finite-time weighted -gain of neutral type switched systems with time-varying delays is presented to measure its disturbance tolerance capability in the fixed time interval. Proofs in detail are accomplished by using multiple Lyapunov–Krasovskii functions. Finally, theoretical results are verified by using a numerical example. [ABSTRACT FROM AUTHOR]

In this study, the problem of finite‐time feedback stabilisation for switched linear input‐delay systems with saturating actuators is addressed by virtue of the comparison‐function‐like method. Finite‐time state feedback stabilisation is discussed and controllers are designed to make the closed‐loop systems finite‐time stable. Moreover, for the case that the states are unmeasured, observers are constructed to estimate the unavailable states and the observer–controller compensator strategy is proposed. Based on the results proposed in this study, information of transient performance of the controlled switched systems can be obtained and bounds of system trajectory are estimated. An example is employed to illustrate the effectiveness of the proposed approach. [ABSTRACT FROM AUTHOR]

In traditional models, only the effect of temperature change of bearings on the heat generation power and thermal contact resistance is considered. But the effect of bearing stiffness and flexibility of crank shaft on the heat generation power is often neglected, thereby impairing the accuracy of the thermal analysis. Therefore, a better thermal model is demanded to accurately analyse the thermal characteristics of a Multi-link ultra-precision press system (MLUPPS). By combining the effect of stiffness of bearing and flexibility of crank shaft on the heat generation power, an improved thermal model of MLUPPS was developed in this work. The model was based on as-derived kinematic and dynamic equations of Multi-link transmission mechanism (MLTM) and flexible dynamic model of crankshaft-bearing system. The dimension chain of thermal error is constructed to analyse the dimensional error between the slider and the work table at the position of Bottom dead point (BDP). The developed thermal model of MLUPPS and its analysis results from this model are in good agreement with the measurement results, and that is more accurate than the traditional one. The simulation results reveal that the maximum temperature rise of MLUPPS occurs at the crank shaft, and the dimensional error between the slider and the work table at the position of BDP is due to thermal expansion fluctuation before the generation and conduction of heat power reaches balance. The temperature rise and thermal error of MLUPPS under different rotation speeds, piling forces and bearing stiffness were also studied. [ABSTRACT FROM AUTHOR]

This paper investigates the global asymptotic stabilization problem for a class of nonlinear systems with time-varying powers. First, adding a power integrator technique is revamped to design a smooth state feedback controller, which is implementable with only upper and lower bounds of the time-varying powers. When the system state is not fully available and the time-varying power is exactly known, a smooth output feedback controller constituted by a state feedback and a nonlinear state observer is constructed to globally stabilize the system. Copyright © 2017 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Smooth output feedback stabilization problem for a family of planar switched nonlinear systems is addressed. First, based on the adding a power integrator technique, the tasks of finding a common Lyapunov function and designing state feedback stabilizing control laws are accomplished simultaneously. Then, combining the state feedback control laws and the reduced-order nonlinear observers, output feedback control laws are designed to globally stabilize the switched nonlinear system under arbitrary switchings, whose subsystems may have uncontrollable/unobservable Jacobian linearizations. [ABSTRACT FROM AUTHOR]

Stability of switched non‐linear systems is addressed from an output‐to‐state point of view. By virtue of the integrability of the outputs of switched non‐linear systems, instead of Lyapunov function, the convergence of the solutions to a set is obtained. Hence, the difficulties of constructing Lyapunov function for switched non‐linear systems can be avoided. Under the condition that the switched non‐linear system is detectable, the conclusion that the switched non‐linear system is asymptotically stable can be reached. Two cases that switched non‐linear systems with multiple output channels or a common output channel are discussed. Numerical examples are presented to verify the proposed method. [ABSTRACT FROM AUTHOR]