From Fault-Diagnosis and Performance Recovery of a Controlled System to Chaotic Secure Communication

Abstract

Chaotic systems are often applied to encryption on secure communication, but they may not provide high-degree security. In order to improve the security of communication, chaotic systems may need to add other secure signals, but this may cause the system to diverge. In this paper, we redesign a communication scheme that could create secure communication with additional secure signals, and the proposed scheme could keep system convergence. First, we introduce the universal state-space adaptive observer-based fault diagnosis/estimator and the high-performance tracker for the sampled-data linear time-varying system with unanticipated decay factors in actuators/system states. Besides, robustness, convergence in the mean, and tracking ability are given in this paper. A residual generation scheme and a mechanism for auto-tuning switched gain is also presented, so that the introduced methodology is applicable for the fault detection and diagnosis (FDD) for actuator and state faults to yield a high tracking performance recovery. The evolutionary programming-based adaptive observer is then applied to the problem of secure communication. Whenever the tracker induces a large control input which might not conform to the input constraint of some physical systems, the proposed modified linear quadratic optimal tracker (LQT) can effectively restrict the control input within the specified constraint interval, under the acceptable tracking performance. The effectiveness of the proposed design methodology is illustrated through tracking control simulation examples. Assumption 2 [Wei et al., 2011]. Let Υ(kT ) ∈ n×m be a matrix of signals generated by the following system Υ(kT + T ) = G d (kT )Υ(kT ) + Φ d (kT ). (10) Assume that G(kT )−L d (kT +T )CG(kT ) is globally asymptotically stable and Φ d (kT + T ) = [Φ(kT ) − L d (kT + T )CΦ(kT )] is a persistently excited signal. 1450151-5 Int. J. Bifurcation Chaos 2014.24. Downloaded from www.worldscientific.com by UNIVERSIDAD POLITECNICA DE MADRID SERVICIO DE BIBLIOTECA UNIVERSITARIA on 01/05/15. For personal use only. W.-T. Hsu et al. 1450151-6 Int. J. Bifurcation Chaos 2014.24. Downloaded from www.worldscientific.com by UNIVERSIDAD POLITECNICA DE MADRID SERVICIO DE BIBLIOTECA UNIVERSITARIA on 01/05/15. For personal use only. Fault-Diagnosis and Performance Recovery Application of the adaptive fault estimator to secure communicationLet the transmitter be the nonlinear time-varying system, and according to the communication structure in Fig. 6 (due to which state masks the message), the equation of the transmitter can be written askT ) + M 1 m(kT )) + H d,k u d (kT ) 1450151-23 Int. J. Bifurcation Chaos 2014.24. Downloaded from www.worldscientific.com by UNIVERSIDAD POLITECNICA DE MADRID SERVICIO DE BIBLIOTECA UNIVERSITARIA on 01/05/15. For personal use only.

A memristive chaotic system and its application in weak signal detection

“…Small variations in system parameters can lead to significant alterations in the system phase trajectory topology. In recent years, there has been extensive research on using chaotic systems for weak signal detection, including applications in fault diagnosis [42][43][44][45] and signal extraction [46]. However, most current studies still rely on classical chaotic systems, which have limitations such as poor system stability and weak noise immunity performance [31,47].…”