自控控制专业外语一,常考的句子和段落

1．1 Introduction

In the first part of this chapter，after a general introduction． The concepts of open-loop and closed—loop control are discussed in the context of a water level control system . 本章第一部分，大体的介绍之后在液位控制系统的内容中介绍的开环控制和闭环控制的概念This example is then used to introduce fundamental considerations in control system analysis and design．这个例子随后被用作介绍控制系统分析和设计的基本思想

In the second part of the chapter，Laplace transforms are discussed and used to define the transfer function of a system．This is a linearized model of the dynamic behavior of the system that will serve as the basis for system analysis and design in most of this book．Block diagram reduction is used to obtain the transfer function of a system consisting of interconnected subsystems.This completes the framework necessary for Chapter in which transfer functions are derived for a variety of physical(sub)systems.本章第二部分，介绍了拉氏变换和用拉氏变换来定义系统的传递函数，这事一个线性化的系统动态特性模型，该模型将在本书的大部分地方作为系统分析和设计的基础，方框图化简是用来获得由相互关联的子系统组成的系统的传函的。这就完成了第二章所需的框架，在第二

章中导出了各种物理（子）系统的传递函数。

1．2 Examples and Classifications of control systems控制系统和分类

Control systems exist in a virtually infinite variety，both in type of application and level of sophistication .实际上，控制系统无论是在应用种类还是复杂程度上都存在许许多多的形式。The heating system and the water heater in a house,are systems in which only the sign of the difference between desired and actual temperatures is used for control．If the temperature drops below a set value，a constant heat source is switched on，to be switched off again when the temperature rises above a set maximum．Variations of such relay or on—off control systems，sometimes quite sophisticated，are very common in practice because of their relatively low cost室内的加热系统和热水箱都仅仅是利用期望温度和实际温度间的偏差信号控制的系统。如果温度降到设定值以下，一个恒定的热源将开启，当温度上升到设定的最高值以上时，关闭恒定热源。有时继电器系统或开关控制系统的变换在实际中非常常见，因为它们相对低廉的价格

In the nature of such control systems．the controlled variable will oscillate continuously between maximum

and minimum limits．For many applications this control is not sufficiently smooth or accurate．In the power steering of a car，the controlled variable or system output is the angle of the front wheels．It must follow the system input,the angle of the steering wheel，as closely as possible but at a much higher power level．在控制系统的特性中，被控变量将会在上限和下限之间持续振荡。对于一些应用，这个控制系统不够顺畅和精确，在车辆的动力转向中，被控变量或系统输出是方向的角度，它必须尽可能地跟踪系统输入-方向盘角度，但是功率水平更高。

(1)Process control OF regulator systems：the controlled

variable，or output，must be held as close as possible to a usually constant desired value, or input, despite any disturbances.过程控制和调节系统：尽管存在干扰，被

控变量或叫输出必须尽可能保持在一个希望的常值也就是输

入上。

This last example brings to mind the distinction between continuous and discrete systems．The latter are inherent in the use of digital computers for control．最后的例子使人想起连续系统和离散系统的差别，后者是属于控制数字计算机的使用。

The classification into linear and nonlinear control