Yufan Zheng

Stabilization of Networked Stochastic Time-Delay Fuzzy Systems With Data Dropout

This paper deals with the problem of stabilization for networked stochastic systems with transmitted data dropout. The plant in the networked control system (NCS) under consideration is a discrete stochastic time-delay nonlinear system represented by a Takagi-Sugeno fuzzy model. Exponential stability criteria of the NCS are developed by using a common quadratic Lyapunov function and a fuzzy Lyapunov function, respectively. A stabilization controller with convergence rate constraint can be designed by solving a set of linear matrix inequalities that is numerically feasible with commercially available software. Three numerical examples are presented to demonstrate the effectiveness of the proposed methods.

A polynomial approach to nonlinear system controllability

Uses a polynomial approach to present a necessary and sufficient condition for local controllability of single-input-single-output (SISO) nonlinear systems. The condition is presented in terms of common factors of a noncommutative polynomial expression. This result exposes controllability properties of a nonlinear system in the input-output framework, and gives a computable procedure for examining nonlinear system controllability using computer algebra.

A Necessary and Sufficient Condition for Consensus of Continuous-Time Agents Over Undirected Time-Varying Networks

The average consensus problem of continuous-time agents in undirected time-varying networks is studied. The network is allowed to be disconnected. A notion called infinite integral connectivity is proposed. Based on the notion, a necessary and sufficient condition for achieving consensus is given. That is, when the network topology is described by an undirected time-varying graph G(t), the agents achieve consensus if and only if the infinite integral graph of G(t) over [0,∞) is connected. This criterion does not hold for directed networks.

INPUT-OUTPUT EQUIVALENCE OF NONLINEAR SYSTEMS AND THEIR REALIZATIONS

Abstract The notion of realization for single-input single-output nonlinear systems is studied based on a new notion of input/output equivalence. This equivalence relation aims to generalize the equivalence of linear time-invariant systems in the sense of the equality of their transfer functions. Necessary and sufficient conditions are given for the existence of a realization, affine or not. A minimal (i.e. accessible and observable) realization may then be derived for those systems which satisfy these conditions, after seeking an equivalent reduced order input/output system.

Nonlinear robust H∞ control via dynamic output feedback ☆

The problem on robust H∞ control for a class of nonlinear systems with parameter uncertainty is studied. Sufficient conditions for the existence of the dynamic output feedback controller are obtained. Under these conditions, the closed-loop systems have robust H∞-performance. A numerical example is given to illustrate the design of a robust controller using the proposed approach.

Stochastic Stability of Networked Control Systems with Network-induced Delay and Data Dropout

This paper deals with the stochastic stability of networked control systems with the presence of network-induced delay and transmitted data dropout. Based on Lyapunov approach, sufficient conditions for the mean-square stability of the networked control system are derived subject that the sequence of transmission interval is driven by an identically independently distributed (i.i.d.) sequence and by a finite state Markov chain, respectively. Stabilization controllers are constructed in terms of linear matrix inequalities correspondingly. An example is provided to illustrate our results

Synchronization for Time-Delay Lur’e Systems with Sector and Slope Restricted Nonlinearities Under Communication Constraints

This paper presents a new approach to the output feedback control problem of master-slave synchronization of time-delay chaotic Lur’e systems with sector and slope restricted nonlinearities under communication constraints. The communication constraints involve measurement quantization and signal transmission delay. By constructing an appropriate Lyapunov functional with the idea of a discretized Lyapunov–Krasovskii functional method and utilizing the sector bound of the logarithmic quantizer, a delay-dependent synchronization criterion is derived. The desired synchronization controller can be obtained by solving a set of linear matrix inequalities. Finally, numerical simulations for Chua’s circuit are proposed to show the effectiveness of the proposed approach.

Global asymptotic stabilization of MIMO bilinear systems with undamped natural response

This paper considers the problem of globally asymptotic stabilization of multi-input multi-output bilinear systems with undamped natural response. It firstly presents a simple sufficient condition for construction of a static state feedback controller. Then under an additional condition on system detectability, two output dynamic feedback controllers with saturation bounded control are constructed. The globally asymptotic stability of the closed loop systems using these controllers are established by using Lyapunov stability approach.

Consensus of multi-agent system under directed network: A matrix analysis approach

This paper investigates the consensus of multiagent system in network (i.e. a swarm). The topological structure of the network is characterized by a digraph. The agents of the network are described by an integrator and distributed in Rm. By means of transforming the Laplacian of the digraph into its Frobenius canonical form the system may be decomposed into one or several minimal-independent subsystems and one or several non-independent subsystems. Each minimal-independent subsystem, which consists of some agents of system, achieves consensus of its own. In other worlds, the agents of the subsystem converge into a state (equilibrium position), which is weighted-average of initial states of agents in the subsystem. Thus, the system may has several local consensus positions. When system consists of one or several non-independent subsystems, we further show that all agents in a non-independent subsystem will converge into a state (aggregation position), which are located inside of a convex-combination set of aggregation positions of minimal-independent subsystems. We study these problem mainly by means of graph theory and matrix theory.

Aggregation stability of multiple agents with general nonlinear attraction and repulsion forces

In this paper we consider the aggregation stability problem of a multi-agents system under network, among the agents there are nonlinear attactive/repulsive forces. Our work generalizes the results given by Gazi and Passino [1] and Chu, Wang and Chen [2], [3], [4] into a very general setting. It shows that the agents of multi-agents system in undirect communication network will asymptotically form a cohesive cluster with finite size if the nonlinear attraction and repulsion functions satisfy some very mild assumptions. We give several numerical simulations demonstrate that the collective behavior of system appear stable cohesion with finite size cohesive areas if the mild assumption is satisfied. We also study the system with directed networks. In such cases the swarms with same nonlinear attactive/repulsive forces may exhibit oscillation and dispersal phenomenon.