现代的控制理论的简单介绍

现代的控制理论的简单介绍(中文4100字,英文2300字)
下列几方面为现代控制理论发展的促进因素:
1.处理更多的现实模型系统的必要性
2.强调向最佳的控制和最佳的系统设计的升级
3.数字化计算机技术的持续发展.
4.当前技术的不成熟.
众所周知的方法在其它知识领域的适用性得到承认.
从容易解决的简单近似的模型到更多的现实模型的转变产生了两种效果：首先，模型必须包括很多的变量。其次，一个十分逼真的模型是尽可能的包括非线性和随时间变化的参数。早先的忽略了系统的一些方面，例如很有可能的一方面就是在环境中有着反馈的交互作用。
在现代科技高度发达的社会，存在一种非常雄心的目标的趋势，这也意味着要处理有着很多相互关联成分的复杂系统，高精确度与高效率的需要改变了控制系统的执行重点。在超频百分比，时间设置，频宽等等方面的经典规范，在很多情况下解决了优化标准如最小能量，最小花费，最小时间控制，优化这些标准时很难避免和不开心的非线性打交道。即使基础系统是线性的和不随时间变化的，优化控制理论显示非线性时间变化控制也被应用到了。
不停发展的计算机技术在控制领域创造了三条最重要的影响。其中一项是有关数字化的超级计算机，较之这本书首印时期，现在能模拟，分析，控制的问题的大小和种类都要大得惊人。

Introduction to Modern Control Theory
Several factors provided the stimulus for the development of modern control theory:
a. The necessary of dealing with more realistic models of system.
b. The shift in emphasis towards optimal control and optimal system design.
c. The continuing developments in digital computer technology.
d. The shortcoming of previous approaches.
e. Recognition of the applicability of well-known methods in other fields of knowledge.
The transition from simple approximate models, which are easy to work with, to more realistic models, produces two effects. First, a large number of variables must be included in the models. Second, a more realistic model is more likely to contain nonlinearities and time-varying parameters. Previously ignored aspects of the system, such as interactions with feedback through the environment, are more likely to be included.
With an advancing technological society, there is a trend towards more ambitious goals. This also means dealing with complex system with a large number of interacting components. The need for greater accuracy and efficiency has changer the emphasis on control system performance. The classical specifications in terms of percent overshoot, setting time, bandwidth, etc. have in many cases given way to optimal criteria such as mini mum energy, minimum cost, and minimum time  operation. Optimization of these criteria makes it even more difficult to avoid dealing with unpleasant nonlinearities. Optimal control theory often dictates that nonlinear time-varying control laws are used, even if the basic system is linear and time-invariant.