A study on dynamical behavior for distributed networked systems under fault

Abstract

Recently, distributed networked systems, such as distributed robots and mobile sensor networks, have been widely considered due to their broad applications. The distributed networked system consists of a large number of small, inexpensive systems deployed over a vast region in a distributed way, in which each small system is capable of collecting, processing information and communicating with neighboring systems. There exist many real-world engineering systems which are well described by distributed networked systems, such as sensor networks, multi-agents systems, and autonomous underwater vehicles. For distributed networked systems, the collaboration among agents is the key factor for achieving the desire tasks. However, the communication among various agents always suffer from different types of physical limitations, for instance, communication range, power, communication quantization, and processing ability. In addition, in networked systems, the distributed behavior brings plenty of essential difficulties in theoretical research. In particular, due to the security requirements in military applications, or source limitations in power systems, the risk of fault in distributed networked system becomes more of a concern. Unfortunately, different kinds of faults emerged due to the unexpected environment effects which can lead to undesirable stability and performance analysis of distributed networked systems. Thus, due to the increasing complexity and safety demand of real-world applications, developing dynamical analysis techniques for distributed networked systems under fault are important. It is highly desirable to exploit effective protocols and methods for preserving the stability and performance of the distributed networked systems under fault. The following issues will be presented in this thesis in detail: (a) fault tolerant multiagents consensus; (b) fault tolerant coordination with quantization due to limited infor mation transmission requirements; (c) state estimation for heterogeneous distributed networks under fault effect. (d) fault estimation for multiple distributed sensor networks; The main contributions of this thesis are listed as follows: • Fault tolerant consensus in multi-agents system using distributed adaptive protocol is investigated. Distributed adaptive online updating strategies for some parameters are proposed based on local information of the network structure. Based on the online updating parameters, distributed adaptive protocols are developed to compensate the fault effects and the uncertainty effects in both leaderless multi-agent system and leader-follower multi-agent system. • The coordination control under fault due to attacks is considered on the security aspect. Passivity based fault tolerant controls for coordination using both logarithmic quantizers and uniform quantizers are investigated. Based on the nonsmooth analytical technique, the effect of the quantization and fault on the coordination results is examined. • Two sets of estimator designs for distributed sensor networks in multi-targets tracking under signal transmission faults due to the uncertain environments are presented. Two-targets tracking distributed sensor networks are firstly proposed to simplify the illustration of complicated mathematics. The estimation approach in two-targets tracking sensor networks is to construct fault estimators for the signal transmission faults. Then, estimators for both fault and state are designed for multi-targets tracking sensor networks. Furthermore, two applications are used to demonstrated the effectiveness of the proposed theoretical results. • The state estimation performance for heterogeneous distributed system with fault based on sampled-data measurement is considered. A performance index for distributed state estimation which augmenting the effect of the amplitude and frequency of the fault is proposed. In addition, distributed state estimators are constructed based on the sampled-data measurement of the heterogeneous distributed system.

Date of Award	2 Oct 2015
Original language	English
Awarding Institution	City University of Hong Kong
Supervisor	Wing Cheong Daniel HO (Supervisor)