毕业设计外文原文万符.doc
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1、编号: 毕业设计外文翻译(原文) 院 (系): 电子工程与自动化学院 专 业: 测控技术与仪器 学生姓名: 李XX 学 号: XXX 指导教师单位: 电子工程与自动化学院 指导教师: XXX 职 称: XXX 2023 年 5 月 20日Information ControlAutomatic ControlAutomatic control has played a vital role in the advance of engineering and science. In addition to its extreme importance in space-vehicle syste
2、ms, missile-guidance systems, robotic systems, and the like, automatic control has become an important and integral part of modern manufacturing and industrial processes. For example, automatic control is essential in the numerical control of machine tools in the manufacturing industries, in the des
3、ign of autopilot systems in the aerospace industries, and in the design of cars and trucks in the automobile industries. It is also essential in such industrial operations as controlling pressure, temperature, humidity, viscosity, and flow in the process industries.Since advances in the theory and p
4、ractice of automatic control provide the means for attaining optimal performance of dynamic systems, improving productivity, relieving the drudgery of many routine repetitive manual operations, and more, most engineers and scientists must now have a good understanding of this field.Control engineeri
5、ng is based on the foundations of feedback theory and linear system analysis, and it integrates the concepts of network theory and communication theory. Therefore control engineering is not limited to any engineering discipline but is equally applicable to aeronautical, chemical, mechanical, environ
6、mental, civil, and electrical engineering. For example, a control system often includes electrical, mechanical, and chemical components. Furthermore, as the understanding of the dynamics of business, social, and political systems increases, the ability to control these systems will also increase.A c
7、ontrol system is an interconnection of components forming a system configuration that will provide a desired system response. The basis for analysis of a system is the foundation provided by linear system theory, which assumes a cause-effect relationship for the components of a system. Therefore a c
8、omponent or process to be controlled can be represented by a block, as shown in Figure 8.1. The input-output relationship represents the cause-and-effect relationship of the process, which in turn represents a processing of the input signal to provide an output signal variable, often with a power am
9、plification. In general, control systems can be categorized as being either open-loop or closed loop. The distinguishing feature between these two types of control systems is the use of feedback comparison for closed-loop operation.1Open-loop Control SystemAn open-loop control system utilizes a cont
10、roller or control actuator to obtain the desired response, as shown in Figure 8.2. An open-loop system is a system without feedback, simplest form of controlling devices. Figure 8.3 illustrates a simple tank-level control system. We wish to hold the tank level h within reasonable acceptable limits e
11、ven though the outlet flow through value V1 is varied. This can be achieved by irregular manual adjustment of the inlet flow rate by valve V2. The system is not a precision system,as it does not have the capability of accurately measuring the output flow rate through valve V1 ,the input flow rate th
12、rough valve V2, or the tank level. Figure 8.4 shows the simple relationship that exists in this system between the input (the desired tank level) and the output (the actual tank level). This control system does not have any feedback comparison,and the term open loop is used to describe this absence.
13、 Figure 8.3 Tank-level control systemOutput(actual tank level)OuputInputFigure 8.1 Process to be controlledProcessOutputActuatingdeviceProcessDisireouputresponseFigure 8.2 An open-loop systemhControl system(valueand operator)Input(desiredtank level)Figure 8.4 Tank-level control system black diagram2
14、Closed-loop Control SystemIn contrast to an open-loop control system, a closed-loop control system utilizes an additional measure of the actual output to compare the actual output with the desired output response. The measure of the output is called the feedback signal. A simple closed-loop feedback
15、 control system is shown in Figure 8.5. A feedback control system is a control system that tends to maintain a prescribed relationship of one system variable to another by comparing functions of these variables and using the difference as a means of control.OutputComparisonControllerProcessDesire ou
16、tputresponseMeasurementFigure 8.5Close-loop control systemClosed-loop control systems derive their valuable accurate reproduction of the input from feedback comparison. An error detector derives a signal proportional to the differences between the input and outputThe closed-loop control system drive
17、s the output until it equals the input and the error is zeroAny differences between the actual and desired output will be automatically corrected in a closed-loop control systemThrough proper design the system can be made relatively independent of secondary inputs and changes in component characteri
18、sticsFigure 8.6 illustrates an automatic tank-level control version of the system shown in Figure 8.3. It can maintain the desired tank level h within quite accurate tolerances even through the output flow rate through value V1 is varied. If the tank level is not correct,an error voltage is develope
19、dThis is amplified and applied to a motor drive that adjusts value V2 in order to restore the desired tank level by adjusting the inlet flow rateA block diagram analogous to this system is shown in Figure 8.7. Because feedback comparison is present,the term closed-loop is used to describe the system
20、s operation. Input(desiredtank level)h+v-vPoweramplifierMotordriveFloatErrorFigure 8.6Automatic tank-level control systemPower amplifierTankFloatMotordriveFigure 8.7 Black diagram of automatic tank-level control systemOutput(actual tank level)Error+-Due to the increasing complexity of the system und
21、er control and the interest in achieving optimum performance, the importance of control system engineering has grown in the past decade. Furthermore, as the system become more complex, the interrelationship of many controlled variables must be considered in the control scheme. A block diagram depict
22、ing a multivariable control system is shown in Figure 8.8.The introduction of feedback enables us to control a desired output and can improve accuracy, but it requires attention to the issue of stability of response.ControllerProcessMeasurementDesiredoutputresponseOutputvariablesFigure 8.8Mulutivari
23、able control systemMicrocontrollerA microcontroller (sometimes abbreviated C, uC or MCU) is a small computer on a single integrated circuit containing a processor core, memory, and programmable input/output peripherals. Program memory in the form of NOR flash is also often included on chip, as well
24、as a typically small amount of RAM. Microcontrollers are designed for embedded applications, in contrast to the microprocessors used in personal computers or other general purpose applications. Microcontrollers are used in automatically controlled products and devices, such as automobile engine cont
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