现代控制理论 Modern control theory
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现代控制理论 早在人类文明出现之初,人们就有了控制自然的愿望。尽管历史上出现过许多控制系统的实例,但是直到18世纪中期才出现一些蒸汽驱动的控制装置。 从二战前的25年开始,电子学特别是电路理论发展迅速。这也得益于奈奎斯特关于稳定性理论方面的研究工作,这一理论到现在还是经典性的。模拟计算机的出现加上电子学的进展奠定了控制系统作为一门学科的基础。计算机的使用开辟了数据采集、计算机控制、状态空间法等现代分析方法的新纪元。 有几个因素激励了现代控制理论的发展: (a) 处理更加真实的系统模型的必要性。 (b) 研究重点朝向最优控制和最小系统设计的转移。 (c) 数字计算技术的不断发展。 (d) 原有方法的短缺。(毕业设计 ) (e) 对于将熟知方法在其他知识领域中的应用的广泛认同。 这种从简单易用的近似模型到更加真实模型的转移产生了几个方面的影响。首先,模型中必须包含众多的变量。其次,更为真实的模型往往具有非线性和时变参数。以前往往忽略的一些系统问题,例如关联问题以及通过环境形成的反馈等,现在却需要考虑。计算机技术的不断发展,已经对控制领域产生了三个方面的影响。影响之一与超大规模的巨型机有关。现在能够进行建模、分析和控制研究的问题的规模和困难级别都已经大大超过了本书第一版时的情况。 Modern control theory The desire to control the forces of narure has been with man since early civilizations. Although many examples of control systems exited in early times, it was not until the mid-eighteenth century that several steam operated control devices appeared. The period beginning about twenty-five years before World War Two saw rapid advances in electronics and especially in circuit theory, aided by the now classical work of Nyquist in the area of stability theory. The advent of the analog computer coupled with advances in electronics saw the beginning of the establishiment of control systems as a science. The availability of computers also opened the era of data logging, computer control, and the state space of modern method of analysis. Several factors provided the stimulus for the development of modern control theory: a. The necessity of dealing with more realistic models of systems. b. The shift in emphasis towards optimal control and optimal system design. c. The continuing developments in digital computer technology. d. The shortcomings of previous approaches. e. A recognition of the applicability of well-known methods in other fields of knowledge. The continuing advances in computer technology have had three principal effects on the controls field. One of these relates to the gigantic supercomputers. The size and class of problems that can now be modeled, analyzed, and controlled are considerably larger than they were when the first of this book was written. |