Time Switching Technique Research Articles

Robust Finite-Time Control of Discrete-Time Switched Positive Time-Varying Delay Systems with Exogenous Disturbance and Their Application

Many practical systems can be modeled in terms of uncertainties, which refer to the differences or errors between actual data and mathematical simulations. However, systems including slight uncertainties and exogenous disturbances may lead to the instability of those systems. Besides, the behavior of systems is preferable to investigate within a prescribed bound over a fixed time interval. Therefore, in this paper, we study a robust finite-time control of discrete-time linear switched positive time-varying delay systems with interval uncertainties and exogenous disturbance. A distinctive feature of this research is that the considered systems consist of finite-time bounded subsystems and finite-time unbounded subsystems. A class of quasi-alternative switching signals is validly designed to analyze the mechanism and switching behaviors of the systems among their subsystems. By utilizing a copositive Lyapunov–Krasovskii functional method combined with the slow mode-dependent average dwell time and the fast mode-dependent average dwell time switching techniques, new sufficient conditions containing several symmetric negative-definite matrices are derived to guarantee robust finite-time control of the systems. These results are applied to a water-quality controllability model in streams to the standard level. Finally, the consistent results between the theoretical analysis and the corresponding numerical simulations are shown.

Finite-Time Boundedness of Linear Uncertain Switched Positive Time-Varying Delay Systems with Finite-Time Unbounded Subsystems and Exogenous Disturbance

The problem of finite-time boundedness for a class of linear switched positive time-varying delay systems with interval uncertainties and exogenous disturbance is addressed. This characteristic research is that the studied systems include the finite-time bounded subsystems and finite-time unbounded subsystems. Both a slow mode-dependent average dwell time and a fast mode-dependent average dwell time switching techniques are utilized reasonably. And by applying a copositive Lyapunov-Krasovskii functional, novel delay-dependent sufficient criteria are derived to guarantee such systems to be finite-time bounded concerning the given parameters and designed switching signal. Furthermore, new finite-time boundedness criteria of the systems without interval uncertainties are also obtained. Finally, the efficiency of the theoretical results is presented in two illustrative examples.

Predictive control strategy for multi-agent relay tracking systems with time delays

This paper investigates the multi-agent systems for target tracking applications, in which the target is cooperatively relay tracked by multiple agents based on the Voronoi diagram. The relay tracking scheme is effective and reduces the tracking time of a target. However, the existence of time delays results in inaccurate determination of boundaries of Voronoi cells. Thus, the replacement of tracking agent is no longer optimal, which consequently affects the tracking time. In order to solve this issue, a predictive controller is proposed for the relay tracking system with time delays. Moreover, the boundaries of Voronoi cells are determined with the predictive values of agents’ information. In order to analyze the stability of the system, an impulse-time-dependent Lyapunov function is designed. Then, the orthogonal polynomials based inequality is applied and the average dwell time switching technique is adopted to solve the difficulty of stability analysis of the overall relay tracking system caused by the agent replacements of time-delay agents. Finally, the effectiveness and advantages of the proposed predictive control method for relay target tracking system with time delays are illustrated by comparative simulations.

Input‐output finite‐time stability of fractional‐order switched singular continuous‐time systems

AbstractThe input‐output finite‐time stability and stabilization of a class of fractional‐order switched singular continuous‐time systems with order 0<α<1 are studied in this paper. First, based on the average dwell time switching technique, by constructing multiple Lyapunov functions, the sufficient conditions of input‐output finite‐time stability for the considered systems are derived in the form of linear matrix inequalities (LMIs). Second, a suitable LMI‐based state feedback controller is designed. Finally, an illustrative example is presented to show the effectiveness of the proposed technique.

Finite-Time Stability and Stabilization of Fractional-Order Switched Singular Continuous-Time Systems

The finite-time stability and stabilization of a class of fractional-order switched singular continuous-time systems with order $$0<\alpha <1$$ are investigated in this paper. First, by employing the average dwell time switching technique, together with the introduction of multiple Lyapunov functions, some sufficient conditions of the finite-time stability and finite-time boundedness are derived for the considered system. Second, based on the obtained conditions, suitable state feedback controllers can be designed if a set of linear matrix inequalities are feasible. Finally, an illustrative example is presented to show the effectiveness of the proposed results.

Wireless-Powered Two-Way Relaying Protocols for Optimizing Physical Layer Security

This paper considers a two-way relay network, in which two sources exchange data through a relay and a cooperative jammer transmits an artificial noise (AN) while a number of nearby eavesdroppers overhear to recover data from both sources. The relay harvests energy from the two source signals and the AN, and then, uses this harvested energy to forward the received signals to the two sources. Each source eliminates its own signal from the relaying signal by self-cancellation and then decodes the data signal received from the other source. For this wireless-powered two-way relay system, we propose two secure relay protocols based on power splitting and time switching techniques. The two protocols are power splitting-based two-way relaying (PS-TWR) and time switching-based two-way relaying (TS-TWR), in which the relay, respectively, controls the power splitting ratio (p) and time switching ratio (α), in order to achieve a balance between the data receiving and the energy harvesting. The optimal values of p and α for each protocol are found analytically to maximize the minimum guaranteed secrecy capacity (C <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">S</sub> <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">min</sup> ) considering multiple eavesdroppers in high signal-to-noise ratio environments. Numerical results show that both the PS-TWR and TS-TWR protocols using the optimized values of p and α achieve the near-optimal C <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">S</sub> <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">min</sup> no matter how many eavesdroppers exist anywhere. Comparisons of the two protocols in various scenarios also show that PS-TWR achieves better C <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">S</sub> <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">min</sup> than TS-TWR because PS-TWR inherently has a shorter vulnerable time for eavesdropping than TS-TWR.

Adaptive Wireless-Powered Relaying Schemes With Cooperative Jamming for Two-Hop Secure Communication

A two-hop relay network is considered, in which an eavesdropper can overhear the relaying signal. To prevent the eavesdropper from decoding this signal, a destination transmits a jamming noise while a source transmits the data signal to the relay. At the same time, the relay can harvest energy from both the source signal and the jamming noise, and use this harvested energy to forward the received signal to the destination. In such a wireless-powered relay system with cooperative jamming, we propose two adaptive relaying schemes based on power splitting and time switching techniques. In the proposed power splitting-based relaying (PSR) and time switching-based relaying (TSR) schemes, the relay controls the power splitting ratio ( ${\rho }$ ) and time switching ratio ( ${\alpha }$ ), respectively, in order to achieve a balance between signal processing and energy harvesting. We find analytically the optimal values of ${\rho }$ and ${\alpha }$ in each scheme to maximize the secrecy capacity under the assumption of high signal-to-noise ratio (SNR). Interestingly, although the eavesdropper’s channel state information (CSI) is used in the derivation of the optimal control parameters ( ${\rho }$ and ${\alpha }$ ), they are shown not to be affected by the eavesdropper’s CSI in a high SNR regime. This implies that the proposed schemes can be effective even for practical environments where there is no eavesdropper’s CSI. Furthermore, simulation results show that they well coincide with the exact solutions in practical environments even though the closed-form solutions are obtained with a high SNR assumption. Moreover, the comparisons of PSR and TSR in various scenarios show that the two relaying schemes have complementary performances depending on the network conditions. Specifically, PSR achieves greater secrecy capacity than TSR when the channel condition is unfavorable to the eavesdropper for wiretapping.

Almost output regulation of switched linear dynamics with switched exosignals

SummaryFor systems with switched linear dynamics and affected by persistent switched exosignals, we propose a new hybrid control approach to achieve not only closed‐loop stability but also tracking and/or rejection of persistent references/disturbances generated by multiple exosystems, namely, output regulation. It is assumed that both controlled plant and exosystem are described by switched linear models. The proposed hybrid controller/output regulator is specified as a switching impulsive system, where the controller states will undergo impulsive jumps at each switching instant. Based on the average dwell time switching technique, it has been shown how to completely reduce the synthesis problem of the hybrid controller to a set of linear matrix equations and linear matrix inequalities. Both continuous‐time and discrete‐time cases are discussed. To demonstrate its usefulness, the proposed hybrid control method has been applied to solve the output regulation problem for a mechanical system. Copyright © 2017 John Wiley &amp; Sons, Ltd.

Finite-Time Stability and Stabilization of Fractional Order Positive Switched Systems

This paper is concerned with finite-time stability analysis and control synthesis of fractional order positive switched systems. By using the linear copositive Lyapunov function integrated with average dwell time switching technique, the finite-time stability of fractional order positive switched systems is first addressed. Then, the finite-time boundedness of fractional order positive switched systems with exogenous input is discussed. Finally, the stabilization of the considered systems is proposed, where a control strategy based on linear programming is designed. Several implemental algorithms are provided to reduce the conservativeness of results. Two numerical examples are given to show the effectiveness of the findings of theory.

Absolutely Exponential Stability and Temperature Control for Gas Chromatograph System Under Dwell Time Switching Techniques.

This paper provides a design strategy for temperature control of the gas chromatograph. Usually gas chromatograph is modeled by a simple first order system with a time-delay, and a proportion integration (PI) controller is widely used to regulate the output of the gas chromatograph to the desired temperature. As the characteristics of the gas chromatograph varies at the different temperature range, the single-model based PI controller cannot work well when output temperature varies from one range to another. Moreover, the presence of various disturbance will further deteriorate the performance. In order to improve the accuracy of the temperature control, multiple models are used at the different temperature ranges. With a PI controller designed for each model accordingly, a delay-dependent switching control scheme using the dwell time technique is proposed to ensure the absolute exponential stability of the closed loop. Experiment results demonstrate the effectiveness of the proposed switching technique.

무선 인지 중계 네트워크에서 이차 사용자의 중계기가 에너지 하베스팅을 사용할 때 처리량을 최대화하기 위한 최적의 하베스팅 시간 분배 방법

 2345)6789:; ?(@A8BC2D. $E4FG 23HIJHK:LMNO@PQ(D. %R)SM*+C6(time switching, TS) TCU, (power splitting, PS) 27D. VWX3  ;<C= 'Y 2  $) *+ ,-8./ 4F(D.  8*+C62 Z=:<[:LMNO;<\@C]^8D. _*)!# $%&'Z  *+ $)&(D. `aO*bcd 9YJ;G *+ 8.e<DVWX4F(./SMf($) *+ 8ghi_*)!# Aj k lD.AbstractEnergy harvesting technique is an energy charging technique for communication device in energy-constrained environment. Recently, energy harvesting technique that harvests energy from wireless radio frequency signal is proposed. Representatively, there are time switching technique and power splitting technique. This paper proposes an optimal harvesting time allocation scheme in a wireless cognitive relay network when secondary user relay uses energy harvesting technique to transmit information. Secondary user relay receives information and energy simultaneously from the secondary user source’s signal via time switching technique. We aim to maximize the instantaneous throughput by optimizing harvesting time of the secondary user relay. Simulation results show that using optimized harvesting time gets larger instantaneous throughput compared to using constant harvesting time.Keyword : Energy harvesting, time switching, cognitive radio, amplify-and-forward relayingmnWX(Special Paper).=opqWX420r42L, 2015s3t(JBE Vol. 20, No. 2, March 2015)http://dx.doi.org/10.5909/JBE.2015.20.2.215ISSN 2287-9137 (Online) ISSN 1226-7953 (Print)