機(jī)械專業(yè)外文翻譯--伺服系統(tǒng)-全文預(yù)覽
【正文】 磁通方向向下。例如。 旋轉(zhuǎn)磁通的速度叫做同步轉(zhuǎn)速，它由線圈電流的頻率決定。當(dāng) A 線圈電流 IA 極性反向時(shí)，磁通的旋轉(zhuǎn)方向也由順時(shí)針變?yōu)榉磿r(shí)針。 N39。 附件 2：外文原文 （復(fù)印件） Servo Systems One means of causing an output shaft to follow the arbitrary motion of an input shaft is the synchro transmitterreceiver system. Another means is the servomechanism or servo system. Synchro systems can operate between shafts separated by a considerable distance but cannot supply torque amplificationthe torque delivered to the load can never exceed the input torque. For this reason, and because the error angle increases when large torques are transmitted, synchro systems are employed only to turn dials and pointers, move control values, and actuate other low torque loads. Servo systems on the other hand, can supply the large torques required to move heavy loads, and only a very small torque need be applied at the input shaft. Remote operation is not inherent in a servo system but may be obtained if data transmission devices, usually synchros, are made part of the system. 1. BASIC REQUIREMENTS OF SERVOS A servo system is a device that has the ability to respond to and carry out an order. A servo system must be able to fulfill five basic requirements. They are: a. A servo must be able to accept an order which defines the result that is desired. b. A servo must be able to evaluate the existing conditions. c. A servo must be able to pare the desired result with the existing conditions, obtaining a difference, or error, signal. d. A servo must be able to issue a correcting order, based on the error signal, which will properly change the existing conditions to the desired result. e. A servo must have the means of carrying out the correcting order. In order for a servo system to meet the five basic requirements, it must possess an error detecting device and a controller that operates the load positioning motor. 2. COMPONENTS OF SERVO SYSTEMS A servo system prises an error indicator and a controller connected to the input and output shafts in the manner shown in Fig. 1. The object of the servo system is to cause the output shaft to repeat the motion of the input shaft by maintaining the error angle (deviation in angular position of output shaft from that of input shaft) as near to zero as possible. The error indicator determines the magnitude and direction of the error angle. Under control of the signal from the error indicator, the controller exerts a torque on the output shaft in a direction to reduce the error. The servo is a closedloop, or feedback system, because a signal applied to the controller causes rotation of the output shaft and thus changes the error angle with the result that an al tered signal is applied to the controller. Figure 1 Basic Servo System. The error indicator and controller may take a wide variety of forms. The controller must include a servo motor or some device for developing the output torque. Servos are classified as electrical, hydraulic
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