毕业论文英文翻译.doc

英文原文：
The World of Control
Introduction
The word control is usually taken to mean regulate , direct , or command . Control systems abound in our environment . In the most abstract sense it is possible to consider every physical object as a control system .
Control systems designed by humans are used to extend their physical capabilities , to compensate for their physical limitations , to relieve them of routine or tedious tasks , or to save money . In a modern aircraft , for example , the power boots controls amplify the force applied by the pilot to move the control surfaces against large aerodynamic forces . The reaction time of a human pilot is too slow to enable him or her to fly an aircraft whit a lightly damped Dutch roll mode without the addition of a yaw damper system . An autopilot ( flight control system ) relieves the pilot of the task of continuously operating the controls to maintain the desired heading , altitude , and attitude . Freed of this routine task , the pilot can perform other tasks , such as navigation and/or communications , thus reducing the number of crew required and consequently the operating cost of the aircraft .
In many cases , the design of control system is based on some theory rather than intuition or trail-and-error . Control theory is used for dealing with the dynamic response of a system to commands , regulations , or disturbances . The application of control theory has essentially two phases : dynamic analysis and control system design . The analysis phase is concerned with determination of the response of a plant ( the controlled object ) to commands , disturbances , and changes in the response is unsatisfactory and modification of the plant is unacceptable , a design phase is necessary to select the control elements ( the controller ) needed to improve the dynamic performance to acceptable levels .
Control theory itself has two categories : classical and modern . Classical control theory , which had its start during World War Ⅱ ， can be characterized by the transfer function concept with analysis and design principally in the Laplace and frequency domains . Modern control theory has arisen with the advent of high-speed digital computers and can be characterized by the state variable concept with emphasis on matrix algebra and with analysis and design principally in the time domain . As might be expected , each approach has its advantages and disadvantages as well as its proponents and detractors .
As compared to modern approach , the classical approach has the tutorial advantage of placing less emphasis on mathematical techniques and more emphasis on physical understanding . Furthermore , in many design situations the classical approach is not adequate , the classical approach solution may aid in applying the modern approach and may provide a check on the more complete and exact design . For these reasons the subsequent articles will introduce the classical approach in detail .
Control System Engineering Design Problem
Control system engineering consists of analysis and design of control configurations . Analysis is the investigation of the properties of an existing system . The design problem is one choice and arrangement of system components to perform a specific task .
Designing a control system is not a precise or well-defined process ; rather , it is a sequence of interrelated events . A typical sequence might be :
1. Modeling of the plant ;
2. Linearization of the plant model ;
3. Dynamic analysis of the plant ;
4. Nonlinear simulation of the plant ;
5. Establishment of the control philosophy & strategy ;
6. Selection of the performance criteria and indices ;
7. Design of the controller ;
8. Dynamic analysis of the complete system ;
9. Nonlinear simulation of the complete system ;
10. Selection of the hardware to be used ;
11. Construction and test of the development system ;
12. Design of the production model ;
13. Test of the production model .
This sequence is not rigid , all-inclusive , or necessarily sequential . It is given here to establish a rationale for the techniques developed and discussed in the subsequent units .

英文翻译：
The World of Control
Introduction
控制通常指调整、指示或者命令。控制系统在我们的周围无处不在。从抽偶像的意义上说，可以将每一个物理对象考虑为一个控制系统。
人类设计的控制系统备于延伸我们的物理能力，弥补我们的物理限制，使我们从例行的或沉闷任务中解脱出来，或者节省经费。例如，在一个现代飞行器中，功率助推装置放大飞行员控制的能力，利用巨大的空气动力移动控制面（飞行器）。飞行员的反应速度太慢，如果不附加阻尼偏航系统，飞行员就无法通过轻微阻尼的侧倾转向方式来驾驶飞机。如果没有自动导航装置（飞行控制系统），飞行员将不停的操作控制器来保持希望的航向、高度和姿势。从这个例行的任务中解脱出来，飞行员就能执行其他的任务，如导航和/或通信，因此减少了需要的机组人员数量和飞机的运行费用。
在许多情况中，控制系统的设计是基于一些理论，而不是直觉或者试凑法。控制理论用于处理系统对命令、调整或者扰动的动态响应。控制理论的应用有两个基本的阶段：动态分析和控制系统设计。分析阶段关注的是确定控制对象对命令、扰动和参数变化的响应。如果动态响应令人满意，则不需要第二个阶段。如果响应不令人满意并且控制对象的修改不能接受，则设计阶段必须选择需要的控制元件（控制器）来提高动态性能以达到可接受的水平。
控制理论有两个类别：经典和现代。经典控制理论起源于第二次世界大战，以传递函数概念为特征，主要在拉氏空间和频域中进行分析和设计。现代控制理论随着高速数字计算机的出现而产生，以状态变量概念为特征，强调矩阵代数、主要在时域中进行分析和设计。可以想象，每一种理论都有其优点和缺点，有其提倡者和批评者。
Control System Engineering Design Problem
控制系统工程包括控制结构的分析和设计。分析是对现存系统性质的研究。设计问题是选择和配置系统组件以执行特定的任务。
设计一个控制系统不是一个精确或者明确定义的过程；而是一系列相关事件。一个典型的系统可能是：
1． 控制对象建模；
2． 对象模型线性化；
3． 控制对象动态分析；
4． 对象非线性模拟；
5． 建立控制原理&控制策略；
6． 性能标准和指标选择；
7． 控制器设计；
8． 整个系统动态分析；
9． 整个系统非线性模拟；
10．所用硬件的选择；
11．开发系统的构建和测试
12．产品模型设计；
13．产品模型测试。
这个系统不是严格的，全部都包括的或者顺序不变的。这里给出的是为后续单元中发展和讨论的技术建立一个基本原理。