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Hu Guoqiang. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2004. / Includes bibliographical references (leaves 87-93). / Abstracts in English and Chinese. / Abstract --- p.i / Acknowledgement --- p.ii / Chapter 1 --- Introduction --- p.1 / Chapter 1.1 --- Nonlinear Control Systems --- p.2 / Chapter 1.2 --- Output Regulation --- p.5 / Chapter 1.3 --- Semiglobal Stabilization --- p.7 / Chapter 1.4 --- A Benchmark Nonlinear Control Problem --- p.8 / Chapter 1.5 --- Contribution of this Thesis --- p.10 / Chapter 2 --- Semiglobal Robust Output Regulation of a Class of Nonlinear Systems via Output Feedback Control --- p.12 / Chapter 2.1 --- Introduction --- p.13 / Chapter 2.2 --- Semiglobal Backstepping Technique --- p.16 / Chapter 2.3 --- Output Regulation Converted to Stabilization --- p.18 / Chapter 2.4 --- Solvability of the Semiglobal Robust Stabilization Problem via Partial State Feedback --- p.23 / Chapter 2.5 --- Design of the Output Feedback Regulator --- p.35 / Chapter 2.6 --- An example --- p.39 / Chapter 2.7 --- Concluding Remarks --- p.46 / Chapter 3 --- Disturbance Rejection of the RTAC system --- p.50 / Chapter 3.1 --- Disturbance Rejection Problem Formulated into Output Regulation Problem --- p.51 / Chapter 3.2 --- Solvability of the Output Regulation Problem via Measurement Output Feedback Control --- p.53 / Chapter 3.3 --- Parameters Design and Simulation Results --- p.57 / Chapter 3.4 --- Concluding Remarks --- p.58 / Chapter 4 --- Robust Disturbance Rejection of the RTAC System --- p.63 / Chapter 4.1 --- Introduction --- p.63 / Chapter 4.2 --- A General Framework for Robust Output Regulation --- p.64 / Chapter 4.3 --- Robust Asymptotic Disturbance Rejection of the RTAC System --- p.69 / Chapter 4.4 --- Algorithms to Design and Optimize the Parameters Kx and L --- p.73 / Chapter 4.5 --- Parameters design and Simulation Results --- p.75 / Chapter 4.6 --- Concluding Remarks --- p.76 / Chapter 5 --- Conclusions --- p.86 / Biography --- p.87 / Bibliography --- p.88 / Appendix A. ITAE Prototype Design --- p.94

在过去的十年间，多智能体系统的协作控制问题引起了广泛的关注。为了解决趋同、编队、蜂拥、群聚等多智能体的协作控制问题，许多研究者提出了各种各样的集中式和分布式控制器。但是这些结果大多是针对线性的多智能体系统的，本论文将利用一些非线性技术去研究线性和非线性的多智能体系统的协作控制问题。 / 1. 有领导者的保持连接的群聚问题: 这类问题的研究主要是针对单点积分器和二重积分器的多智能体系统。为了保持网络的原始链接，我们引入了有界的势能函数，基于这样的势能函数，我们提出了非线性的控制器，所以尽管这样的多智能体系统本身是线性的，但闭环系统是非性的。因此我们利用李雅普诺夫定理来分析闭环系统的性能,并进行了大量的仿真实验来衡量我们的控制器的有效性。具体的结果列如下: / 我们首先研究的系统是带领导的单点积分器的多智能体系统，其中领导是由线性自治系统生成。现有的结果只能处理领导者信号是恒定的或者是斜波信号。而我们提出了一个分布式的状态反馈的控制器，不管领导者的信号是阶跃，斜波还是正弦信号，我们提出的这一控制器都能保持整个系统的原始连接，并且同时能实现各个子系统对领导者的渐近跟踪。 / 我们并进一步研究了二重积分器的多智能体系统，而且这样的系统受到外部信号的干扰。领导者的信号和干扰信号可以是阶跃信号，斜波信号以及具有任意振幅和初始相位的正弦信号的组合。受到一些输出调节理论的启发，我们同时提出了分布式的全状态反馈控制器和带有分布式观测器的输出反馈控制器。尽管存在外部干扰信号，这两种控制器都能保持整个系统的初始连接，同时能实现各个子系统对领导者的渐近跟踪的目标。 / 值得注意的是尽管我们研究是多智能体系统的群聚问题，这种技术同时能用来解决其他类似的编队、蜂拥等协作控制问题。 / 2. 非线性多智能体系统的合作输出调节问题: 我们首先明确地提出了什么是非线性多智能体系统的合作输出调节问题。这个问题可以看作是有领导者的趋同问题的一般化。这个非线性多智能体系统包含了一个领导者和各个子系统，其中领导者的信号由一外部线性自治系统产生，而每个子系统是含有不确定参数的非线性系统，并且这些子系统受到外部信号的干扰。首先我们引入分布式的内模，然后通过坐标变换，得到了一个多输入多输出的增广系统，之后我们把非线性多智能体系统的合作输出调节问题转化成了这个增广系统的全局镇定问题，最后一系列标准的假设下，我们提出了一分布式输出反馈控制器解决了镇定问题，从而解决了输出调节问题。具体来说，假设通信图是连接的，如果我们能解决每个子系统的输出调节问题，那我们提出的分布式输出反馈调节器就能解决这个多智能体系统的合作输出调节问题。我们也把提出的这一控制器应用于洛伦兹多智能体系统的合作输出调节问题。 / Over the past decade, the coordinated control problems for multi-agent systems have attracted extensive attention. Both centralized and distributed control protocols have been developed to study such multi-agent coordinated control problems as consensus, formation, swarming, flocking, rendezvous and so on. However, most papers employ standard linear control techniques. The results are mainly limited to linear multi-agent systems. In this thesis, we will study some coordinated control problems of both linear and nonlinear multi-agent systems by some advanced nonlinear techniques. / This thesis has mainly studied two problems. / i) The leader-following rendezvous with connectivity preservation. We have studied this problem for both single integrator and double integrator multi-agent systems by nonlinear control laws utilizing bounded potential function. Although the model of multi-agent system is linear, the closed-loop system is nonlinear due to the employment of nonlinear control laws. We have developed a Lyapunov-based method to analyze the performance of the closed-loop system, and conducted extensive simulations to evaluate the effectiveness of our control schemes. The specific results are summarized as follows. / We have studied the case where the leader system is a linear autonomous system and the follower system is a multiple single-integrator system. The existing results can only handle the case where the leader signal is a constant signal or ramp signal and the control law is discontinuous. By introducing an exosystem, we have proposed a distributed state feedback smooth control law. For a class of reference signals such as step, ramp, and sinusoidal signals, our control law is able to maintain the connectivity of the system and, at the same time, achieve asymptotic tracking of all followers to the output of the leader system. / We have also studied a leader-following rendezvous problem for a double integrator multi-agent system subject to external disturbances. Both the leader signal and disturbance signal can be a combination of step signal, ramp signal and sinusoidal signal with arbitrary amplitudes and initial phases. Motivated by some techniques in output regulation theory, we have developed both distributed state feedback control protocol and distributed output feedback control protocol which utilizes a distributed observer. Both of our control laws are able to maintain the connectivity of an initially connected communication network, and, at the same time, achieve the objective of the asymptotic tracking of all followers to the leader regardless of external disturbances. / It is noted that even though we have only studied the rendezvous problem, the techniques of this thesis can also be used to handle other similar problems such as formation, flocking, swarming, etc. / ii) Cooperative output regulation problem of nonlinear multi-agent systems. We have formulated the cooperative output regulation problem for nonlinear multi-agent systems. The problem can be viewed as a generalization of the leader-following consensus/ synchronization problem in that the leader signals are a class of signals generated by an exosystem, each follower subsystem can be subject to a class of external disturbances, and individual follower subsystems and the leader system have different dynamics. We first show that the problem can be converted into the global stabilization problem of a class of multi-input, multi-output nonlinear systems called augmented system via a set of distributed internal models. Then we further show that, under a set of standard assumptions, the augmented system can be globally stabilized by a distributed output feedback control law. We have solved the cooperative output regulation problem of uncertain nonlinear multi-agent systems in output feedback form. The main result can be summarized as follows: assuming the communication graph is connected, then the problem can be solved by a distributed output feedback control law if the global robust output regulation problem for each subsystem can be solved by an output feedback control law. We have also applied our approach to solve a leader-following synchronization problem for a group of Lorenz multi-agent systems. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Dong, Yi. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2013. / Includes bibliographical references (leaves 102-111). / Abstract also in Chinese. / Abstract --- p.i / Acknowledgement --- p.v / Chapter 1 --- Introduction --- p.1 / Chapter 1.1 --- Literature Review --- p.1 / Chapter 1.1.1 --- Leader-following rendezvous with connectivity preservation problem --- p.3 / Chapter 1.1.2 --- Cooperative output regulation problem of nonlinear multi-agent systems --- p.4 / Chapter 1.2 --- Thesis Contributions --- p.4 / Chapter 1.3 --- Thesis Organization --- p.6 / Chapter 2 --- Fundamentals --- p.8 / Chapter 2.1 --- Review of Graph Theory Notation --- p.8 / Chapter 2.2 --- Review of Linear Output Regulation --- p.9 / Chapter 2.2.1 --- Regulator equations --- p.10 / Chapter 2.2.2 --- Linear feedback control laws --- p.11 / Chapter 2.2.3 --- Barbalat’s Lemma --- p.12 / Chapter 2.3 --- Review of Nonlinear Output Regulation --- p.12 / Chapter 2.3.1 --- From nonlinear output regulation to stabilization --- p.13 / Chapter 2.3.2 --- Construction of internal model --- p.15 / Chapter 2.3.3 --- Some theories --- p.17 / Chapter 3 --- Leader-following Rendezvous with Connectivity Preservation of Single-integrator Multi-agent Systems --- p.19 / Chapter 3.1 --- Introduction --- p.19 / Chapter 3.2 --- Problem Formulation --- p.20 / Chapter 3.3 --- Solvability of Problem --- p.22 / Chapter 3.4 --- Example --- p.28 / Chapter 3.5 --- Conclusion --- p.28 / Chapter 4 --- A Leader-following Rendezvous Problem of Double Integrator Multiagent Systems --- p.30 / Chapter 4.1 --- Introduction --- p.30 / Chapter 4.2 --- Problem Formulation --- p.32 / Chapter 4.3 --- Main Result --- p.34 / Chapter 4.4 --- Illustrative Examples --- p.41 / Chapter 4.4.1 --- Example 1 --- p.41 / Chapter 4.4.2 --- Example 2 --- p.42 / Chapter 4.5 --- Conclusion --- p.43 / Chapter 5 --- Leader-following Connectivity Preservation Rendezvous of Multi-agent Systems Based Only Position Measurements --- p.46 / Chapter 5.1 --- Introduction --- p.46 / Chapter 5.2 --- Problem Formulation --- p.47 / Chapter 5.3 --- Construction of Distributed Controller --- p.49 / Chapter 5.4 --- Example --- p.55 / Chapter 5.5 --- Conclusion --- p.58 / Chapter 6 --- Cooperative Global Robust Output Regulation for Nonlinear Multiagent Systems in Output Feedback Form --- p.61 / Chapter 6.1 --- Introduction --- p.61 / Chapter 6.2 --- Preliminaries --- p.63 / Chapter 6.3 --- Construction of Distributed Controller --- p.66 / Chapter 6.4 --- Application to Lorenz Multi-agent Systems --- p.69 / Chapter 6.5 --- Conclusion --- p.72 / Chapter 7 --- Cooperative Global Output Regulation for a Class of Nonlinear Multiagent Systems --- p.75 / Chapter 7.1 --- Introduction --- p.75 / Chapter 7.2 --- Preliminaries --- p.77 / Chapter 7.3 --- Solvability of Problem --- p.82 / Chapter 7.4 --- Application to Hyper-Chaotic Lorenz Multi-agent Systems --- p.90 / Chapter 7.5 --- Concluding Remarks --- p.97 / Chapter 8 --- Conclusions and Future Work --- p.100 / Chapter 8.1 --- Conclusions --- p.100 / Chapter 8.2 --- Future Work --- p.101 / Bibliography --- p.102 / Biography --- p.112

Thesis (Ph. D.)--University of Texas at Austin, 2003. / Vita. Includes bibliographical references. Available also from UMI Company.

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Packet-switched communication networks such as today's Internet are built with several interconnected core and distribution packet forwarding routers and several sender and sink transport agents. In order to maintain stability and avoid congestion collapse in the network, the sources control their rate behavior and voluntarily adjust their sending rates to accommodate other sources in the network. In this thesis, we study one class of sender rate control that is modeled using continuous first-order differential equation of the sending rates. In order to adjust the rates appropriately, the network sends continuous packet-loss feedback to the sources. We study a form of closed-loop feedback congestion controllers whose rate adjustments exhibit a nonlinear form. There are three dimensions to our work in this thesis. First, we study the network optimization problem in which sources choose utilities to maximize their underlying throughput. Each sender maximizes its utility proportional to the throughput achieved. In our model, sources choose a utility function to define their level of satisfaction of the underlying resource usages. The objective of this direction is to establish the properties of source utility functions using inequality constrained bounded sets and study the functional forms of utilities against a chosen rate differential equation. Second, stability of the network and tolerance to perturbation are two essential factors that keep communication networks operational around the equilibrium point. Our objective in this part of the thesis is to analytically understand the existence of local asymptotic stability of delayed-feedback systems under homogeneous network delays. Third, we propose a novel tangential controller for a generic maximization function and study its properties using nonlinear optimization techniques. We develop the necessary theoretical background and the properties of our controller to prove that it is a better rate adaptation algorithm for logarithmic utilities compared to the well-studied proportional controllers. We establish the asymptotic local stability of our controller with upper bounds on the increase / decrease gain parameters.

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In this thesis, a class of control and identification methods on a typical laboratory process - a ball and beam system - are discussed. The ball and beam is a common laboratory process which contains nonlinearity, a double integrator and time-delay. In our project, the hardware made by Wincon (Quanser SRV02 +BB01) is used. The main contribution of this work is the development of a variety of controller design methods, which together with suitable parameter identification techniques provide tools for rapid prototyping for real time control of processes within the laboratory, in preparation for industrial implementation of more complex schemes. The novelty of this work lies in the use of model predictive control (MPC) methods based on a non-minimal state space formulation, which permits the inclusion of process measurements and actuations in the state vector, leading to controller designs which are immediately ready for on-line implementation. A linear MPC controller based on a non-minimal state space model is based on an approximate linear model. The results from simulation and online experiment show that the linear MPC controller realizes a satisfying reference tracking in the face of nonlinearity and time-delay. In the following chapter, a nonlinear Hammerstein model is identified, which is a type of reliable structure for describing nonlinear plants. A nonlinear MPC scheme is developed based on the Hammerstein model. An inversion block is created to cancel the effect of the nonlinearity. The performance IS also tested in both simulation and experiment. Finally, MPC is combined with sliding mode control. The non-minimal state space model is also used here. In the first part of this chapter, the idea underlying sliding mode control contributes a method of modifying the definition of the cost function in MPC. In the second half, MPC is used to design the switching surface in sliding mode control. The performance of tests on the example (ball and beam system) illustrates that these are both valid methods for dealing with complex processes.

Thesis (Ph.D.)--Auburn University, 2006. / Abstract. Vita. Includes bibliographic references (ℓ. 64-65)

Thesis (M.Sci.)--Massachusetts Institute of Technology, 1959. / Includes bibliographical references (leaf 98).