自动化专业英语第三课翻译（Third courses in English for automation）.doc

自动化专业英语第三课翻译（Third courses in English for automation） The desired basic control actions and industrial automatic control automatic controller compares the actual value of the plant output value determines the deviation, and produces a control signal which will reduce the deviation to zero or to a small value. The way in which the automatic controller produces the control signal is called control action. Here, we should basically control industrial automation controllers that are commonly used in action. First, we introduce the principles of operation of automatic controllers and methods for generating a variety of control signals, such as using derivative and integral error signals. Next, we discuss the impact, especially the control mode, of system performance. Then, we should give a brief discussion of the method of reducing the impact of external disturbances on system performance. Finally, we will introduce the current basic principles of fluidic amplifiers, and discuss the application of fluidic devices. Industrial automatic controllers may be classified according to their control action: (1) two position or on-off controllers; (2) the proportional controller; (3) the integral controller; (4) according to the proportional plus integral controller; (5) proportional plus derivative controller; (6) proportional plus derivative plus integral controller. Most industrial automatic controllers use electric or pressurized fluids, such as oil or air, as power sources. The automatic controller may also be employed according to the sort of power, such as pneumatic control, hydraulic controller, or electronic controller. What kind of controller must be used to determine the nature of the plant and job conditions, these factors include safety, availability, reliability, accuracy, weight and size. The automatic controller must detect drive error signals, usually at a very low power level, and extend to a fairly high level. Therefore, the amplifier is necessary. The output of