畢業(yè)設(shè)計（論文）附二: 外文翻譯High Precise Control Method for a New Type ofPiezoelectric Electro—hydraulic Servo Valve Abstract：A new type of piezoelectric electro-hydraulic servo valve system was proposed． And then multilayer piezoelectric actuator based on new piezoelectric ceramic material was used as the electricity-machine converter of the proposed piezoelectric electro-hydraulic servo valve. The proposed piezoelectric electro -hydraulic servo valve has ascendant performance compared with conventional ones.But the system is of high nonlinearity and uncertainty, it cannot achieve favorable control performance by conventional control method．To develop an efficient way to control piezoelectric electro—hydraulic servo valve system．A high—precise fuzzy control method with hysteresis nonlinear model in feedforward loop was proposed. The control method is separated into two parts：a feedforward loop with Preisach hysteresis nonlinear model and a feedback loop with high-precise fuzzy contro1. Experimental results show that the hysteresis loop and the maximum output hysteresis by the PID control method are 4.22％ and 2．11 pm, respectively；the hysteresis loop and the maximum output hysteresis by the proposed control method respectively are 0．74％ and 0．37μm，respectively；the maximum tracking error by the PID control method for sine wave reference signal is about 5．02％ , the maximum tracking error by the proposed control method for sine wave reference sign al is about 0．85％．contro1．Key words：piezoelectric electro—hydraulic servo valve；hysteresis nonlinearity；Preisach model；fuzzy control1 IntroductionElectro—hydraulic servo system is widely applied in industrial domain nowadays．for example．robot drive，machine building, architectural engineering．The electro-hydraulic servo valve is the kernel of the electro-hydraulic servo system,and its performance has decisive effect Of the whole system．The conventionaldrive mode of electro．hydraulic servo valve has lower resolution and narrower work band width，which restricts the applications of the electro-hydraulic servo valve．The proposed piezoelectric electro-hydraulic servo valve adopts multilayer piezoelectric actuator as electricity-machine converter. This Hew type of piezoelectric electro-hydraulic servo valve has better dynamicperformance than that of conventional ones． At present，with the research and the development of new-type actuator based on new type materials, it is possible to make the new electricity-machine converter with high frequency. New materials include piezoelectric ceramic materials, magnetostrjctive materials, shape memory alloys．Thereinto, multilayer piezoelectric actuators based on new piezoelectric ceramic materials have many merits such as small cubage，high resolution，high frequency and large drive force．Hence，they are widely used in the micro-position device of machine tools and other precision machines [1-6]．However, they also have many shortcomings，for example，hysteresis nonlinearity model in feedforward loop was proposed．2 Work principle and characteristic of new-type of piezoelectric electro-hydraulic ValveBecause the pulling force capacity of multilayer piezoelectric actuator is very poor, it cannot make the slide valve of the electro, hydraulic servo valve bidirectionallv move. Two multilayer piezoelectric actuators were adopted to solve this problem [7-8]. The shortcoming of this method is high cost and system is difficult to contro1. Utilizing the restoring force of a leaf spring，one multilayer piezoelectric actuator can realize bidirectional movement of the slide valve in this paper. W hen the voltage imposed on multilayer piezoelectric actuator 1s increased，multilayer piezoelectric actuator will elongate and drive the slide valve to move towards the left，which makes the leaf spring deform．On the contrary, when the voltage imposed on multilayer piezoelectric actuator is reduced，multilayer piezoelectric actuator will be shortened and then drive the slide valve move towards the right by the action of the restoring force of the leaf spring.The structure of new type of piezoelectric electro—hydraulic servo valve is shown in Fig．1． The input-output characteristic of the new type of piezoelectric electro-hydraulic servo valve system indicates that it has hysteresis nonlinearity with nonloca1 memory(see Fig．2). At any reachable point L (Ua ，Ya)in input-output diagram，the number of alternative curve that describes the future path of hysteresis nonlinearity with nonloca1 memory is infinite. Namely, the future output of the system depends not only on the current output Ya and future input，but also on the past history of input value’s extremum. Hence, the output response of new type of piezoelectric electro-hydraulic servo valve to an applied input voltage becomes unpredictable. In the system，there exist other nonlinearities such as force of friction and work dead zone of valve, furthermore，damping coefficient an。