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機械類數(shù)控外文翻譯外文文獻英文文獻數(shù)控(已改無錯字)

2022-07-25 03:44:38 本頁面
  

【正文】 ic and CNC milling machinesTo function as a system manager, a DSP must have robust onchip I/O and other peripherals. The event manager of the ‘240 is unlike any other available on a DSP . This applicationoptimized peripheral unit , coupled with the high performance DSP core, enables the use of advanced control techniques for highprecision and highefficiency full variablespeed control of all motor types. Include in the event manager are special pulsewidth modulation (PWM) generation functions, such as a programmable deadband function and a space vector PWM state machine for 3phase motors that provides stateoftheart maximum efficiency in the switching of power transistors.There independent up down timers, each with it’s own pare register, support the generation of asymmetric (noncentered) as well as symmetric (centered) PWM waveforms.OpenLoop and ClosedLoop ControlOpenloop Control SystemsThe word automatic implies that there is a certain amount of sophistication in the control system. By automatic, it generally means That the system is usually capable of adapting to a variety of operating conditions and is able to respond to a class of inputs satisfactorily . However , not any type of control system has the automatic feature. Usually , the automatic feature is achieved by feed.g the feedback structure, it is called an openloop system , which is the simplest and most economical type of control lies in the fact that one may not know the exact characteristics of the further ,which has a definite bearing on the indoor temperature. This alco points to an important disadvantage of the performance of an open loop control system, in that the system is not capable of adapting to variations in environmental conitions or to external disturbances. In the case of the furnace control, perhaps an experienced person can provide control for a certain desired temperature in the house。 but id the doors or windows are opened or closed intermittently during the operating period, the final temperature inside the house will not be accurately regulated by the openloop control.An electric washing machine is another typical example of an openloop system , because the amount of wash time is entirely determined by the judgment and estimation of the human operator . A true automatic electric washing machine should have the means of checking the cleanliness of the clothes continuously and turn itsedt off when the desired degised of cleanliness is reached.ClosedLoop Control SystemsWhat is missing in the openloop control system for more accurate and more adaptable control is a link or feedback from the output to the input of the system . In order to obtain more accurate bontrol, the controlled signal c(t) must be fed back and pared with the reference input , and an actuating signal proportional to the difference of the output and the input must be sent through the system to correct the error. A system with one or more feedback pat(s like that just described is called a closedloop system. human being are probably the most plex and sophisticated feedback control system in existence. A human being may be considered to be a control system with many inputs and outputs, capable of carrying out highly plex operations.To illustrate the human being as a feedback control system , let us consider that the objective is to reach for an object on aperform the task. The eyes serve as a sensing device which feeds back continuously the position of the hand . The distance between the hand and the object is the error , which is eventually brought to zero as the hand reacher the object. This is a typical example of closedloop control. However , if one is told to reach for the object and then is blindolded, one can only reach toward the object by estimating its exact position. It isAs anther illustrative example of a closedloop control system, shows the block diagram of the rudder control system ofThe basic alements and the bloca diagram of a closedloop control system are shown in fig. In general , the configuration of a feedback control system may not be constrained to that of fig amp。 . In plex systems there may be multitude of feedback loops and element blocks. 數(shù)控在先進制造技術(shù)領(lǐng)域最根本的觀念之一是數(shù)控(NC)。數(shù)控來臨之前,所有機床是手工操作和控制。手動控制機床有許多限制,或許沒有比操作者的技能更突出。用手動控制,產(chǎn)品質(zhì)量直接相關(guān),并僅限于操作者的技能。數(shù)控具有重要的意義在于它擺脫手動控制機床。數(shù)控機床意味著,機器操作和其他手寫機器操作系統(tǒng)的到來。操作機床,數(shù)控技術(shù)員只要寫出機床的指示程序,機床就會自動控制,它必須與一個接口接受和解碼程序指示,作為一個讀者已知的設(shè)備。數(shù)控開發(fā),克服了人工操作的局限性,并且已經(jīng)完成。數(shù)控機床比手動操作機器更為準確,他們可以使得生
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