外文翻譯---控制系統(tǒng)的介紹(文件)
【正文】 nalflow representation of the physical system is called a block diagram. Arrows are used to show the input entering and the output leaving the control system. Tanklevel controlsystem black diagram Tanklevel control system 3 This control system does not have any feedback parison, and the term open loop is used to describe this absence. illustrate a fieldcontrolled dc motor turning a cutting wheel at a constant speed. When a piece of wood is applied to the surface of the cutting wheel, it acts as a disturbing torque of the motor any results in a reduction of the speed of the cutting wheel, assuming that control signal remains constant. This situation can be represented as shown in . The symbol appearing between the motor and the load represents a substractor. The effect of disturbance torques, or other secondary inputs, is detrimental to the accurate functioning of an open –loop control system, it has no way of automatically correcting its output, because there is no feedback parison. Closedloop Control System Closedloop control systems derive their valuable accurate reproduction of input from feedback parison. An error detector derives a signal proportional to the differences between the input and output. The closedloop control system drives the output until it equals the input and the error is zero. Any differences between the Fieldcontrolled dc motor Fieldcontrolled dc motor having a disturbance torque 4 active and desired output will be automatically corrected in a closedloop control system. Through proper design, the system can be made relatively independent of secondary inputs and changes in ponent character
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