Jun-Juh Yan

Stability Analysis of Takagi–Sugeno Fuzzy Cellular Neural Networks With Time-Varying Delays

This correspondence investigates the global exponential stability problem of Takagi-Sugeno fuzzy cellular neural networks with time-varying delays (TSFDCNNs). Based on the Lyapunov-Krasovskii functional theory and linear matrix inequality technique, a less conservative delay-dependent stability criterion is derived to guarantee the exponential stability of TSFDCNNs. By constructing a Lyapunov-Krasovskii functional, the supplementary requirement that the time derivative of time-varying delays must be smaller than one is released in the proposed delay-dependent stability criterion. Two illustrative examples are provided to verify the effectiveness of the proposed results

Parameter identification of chaotic systems using evolutionary programming approach

This paper is concerned with the parameter identification problem for chaotic systems. An evolutionary programming (EP) approach is newly introduced to solve this problem. The unknown parameters of chaotic systems are taken as a parameter vector, and will be optimally approximated to the exact values of parameters by using the proposed EP algorithm. The unified chaotic systems including Lorenz, Lu and Chen systems are used in an illustrative example to show the validity of the proposed method.

Design of robust active queue management controllers for a class of TCP communication networks

This paper describes the design of active queue management (AQM) controllers for a class of TCP communication networks. In TCP/IP networks, the packet-dropping probability function is considered as a control input. Therefore, a TCP AQM controller was modeled as a time-delayed system with a saturated input. The objective of the work described here was to design robust controllers capable of achieving the desired queue size and guaranteeing asymptotic stability of the operating point. To achieve this aim, we have proposed two control strategies, namely a static state feedback controller and an observer-based controller. By applying the Lyapunov-Krasovskii functional approach and the linear matrix inequality technique, control laws and delay-independent stability criteria for the AQM controllers were derived. The performance of the two control schemes was evaluated in various network scenarios via a series of numerical simulations. The simulation results confirm that the proposed schemes outperform other AQM schemes.

EP-based PID control design for chaotic synchronization with application in secure communication

In this paper, the evolutionary programming (EP)-based proportional-integral-derivative (PID) control design is presented for synchronization of chaotic systems with application in secure communication. A PID controller is developed via the EP algorithm. By using the EP algorithm, optimal control gains in PID controlled chaotic systems are derived such that a performance index of integrated absolute error (IAE) is as minimal as possible. Moreover, as an application, the proposed EP-based PID control scheme is then applied to a chaotic secure communication system. To verify the system performance, basic electronic components containing OPA, resistor and capacitor elements are used to implement the proposed PID-based chaotic secure communication system. Finally, both simulation results and the circuit experiments demonstrate the proposed PID schemes success in the communication application.

GA-based PID active queue management control design for a class of TCP communication networks

Active queue management (AQM) is a key congestion control scheme for reducing packet loss and improving network utilization in TCP/IP networks. This paper proposes a proportional-integral-derivative (PID) controller as an active queue manager for Internet routers. Due to the limitations of packet-dropping probability and the effects of propagation delays in TCP networks, the TCP AQM network was modeled as a time-delayed system with a saturated input. An improved genetic algorithm is employed to derive optimal or near optimal PID controller gains such that a performance index of integrated-absolute error (IAE) is minimized, and thereby a stable queue length, low packet loss, and high link utilization for TCP networks are guaranteed. The performance of the proposed control scheme is evaluated in various network scenarios via a series of numerical simulations.

Adaptive variable structure control for chaos suppression of unified chaotic systems

This paper investigates the chaos suppression problem for a class of unified chaotic systems subject to uncertainties and control input with dead-zone nonlinearity. Using the variable structure control technique, a robust adaptive control law is established to suppress chaos in a class of unified chaotic systems even with unknown uncertainties and dead-zone nonlinearity in input. In particular, a switching surface is newly proposed to simplify the task of ensuring the stability of the closed-loop system in the sliding mode. Numerical results validate the effectiveness of the proposed adaptive control scheme.

The design of quasi-sliding mode control for a permanent magnet synchronous motor with unmatched uncertainties

In this study, the concept of a quasi-sliding mode control (QSMC) is introduced for the robust control of a permanent magnet synchronous motor (PMSM) system subjected to unmatched uncertainties, and even with input nonlinearity. On the basis of the new concept of QSMC, continuous control is obtained, to avoid the chattering phenomenon. As expected, the system state can be stabilized and driven into a predictable neighborhood of zero. Also, this approach only uses a single controller to achieve chaos control, which reduces the cost and complexity of implementation. The results of numerical simulations demonstrate the validity of the proposed QSMC design method.

Reliable synchronization of nonlinear chaotic systems

This article addresses the reliable synchronization problem for a general class of chaotic systems. By combining the Lyapunov stability theory with the linear matrix inequality (LMI) optimization technique, a reliable feedback controller is established to guarantee synchronization between the master and slave chaotic systems even though some control component (actuator) failures occur. Finally, an illustrative example is provided to demonstrate the effectiveness of the results developed in this paper.

Design and implementation of the Sprott chaotic secure digital communication systems

Abstract In this paper, synchronization of Sprott chaotic systems and its application in secure communication are presented. We first utilize a proportional-integral-derivative (PID) control scheme to solve the synchronization problem of chaotic systems. Then for the purpose of application to secure communication, a state signal of the analog chaotic system is converted to a digital train with variable pulse width (square wave with random frequency) by voltage controlled oscillator (VCO). The original digital message is masked by the digital train generated from VCO in the chaotic transmitter via a logical exclusive-OR (XOR) operation and it can be successfully recovered by another VCO and XOR operation at the chaotic receiver due to the synchronization. To verify the system performance, basic electronic components containing operational amplifiers (OPAs), resistors and capacitors are used to implement the proposed PID-based chaotic secure communication system. Finally, the experimental results validate the proposed chaotic communication approach.

Quasi-Sliding Mode Control of Chaos in Permanent Magnet Synchronous Motor

A quasi-sliding mode control (QSMC) to suppress chaos for a permanent magnet synchronous motor (PMSM) with parameters fall into a certain area is proposed in this paper. Especially, based on the new concept of QSMC, continuous control input is obtained to avoid chattering phenomenon. As expected, the system states can be driven to zero or into a predictable and adjustable bound even when uncertainties are present. Numerical simulations demonstrate the validity of the proposed QSMC design method.