【文章內(nèi)容簡介】 ilter out the signals different with the exciting signal of the flow signal and serve it as the response signals of the servo valve to be tested . The two signals are entered into the puter by turns after sampling , and epuate the autospectral spectrum of the exciting signals GXX(f) and crosspower spectrum of exciting signals and responding signals GXY(f) . By this method we can get the frequency response H (f) = GXX (f) / GXY (f) . When we do the test of the dynamic characteristics , close switch valve 6 and open valve 8 . An independent signal generator produces scaning sinusoidal signal . The signal is entered into the servo amplifier after amplification and drive the dynamic cylinder to move . With the help of the speed sensor installed on the dynamic cylinder ,we can equate the output flow of the servo valve being tested . 8 And the shift sensor installed on the other side can be used for preventing the dynamic cylinder from deviating from the central position . 4. Current circuit of the test system The signals need to be collected during the static characteristics test of the testing system signals include Current signals of the servo valve coil to be tested, Pressure of inlet oil port , Pressure signal of load port A and B , Pressure signal of leaking mouth , Flow signal of load port A and B , Flow signal of leaking mouth . The signals need to be collected during the dynamic characteristics test include current signals of valve coil to be tested ,Voltage signal outputed by speed sensor signals outputed by the testing system include setting value of pressure of the proportional relief valve , Stimulating signals of valve coil to be tested produced by signal generator . The amplify signals of the servo valve to be tested in the above signals are current signals and the others are voltage signal . As these signals detected by the sensor usually contain noise or through modulation . So the signals should go through corresponding treatment before being inputed into the puter , then converted into digital signals by A/D converter for further use . Separate digital signal generator is used during the test ,and the signal generator use single chip microputer 16 as its core and can produce triangle waves, sine waves, square waves, linear sweep sine wave signals with the frequency of 0～ 800HZ and so on for servo valve testing . Signal generator municate with the main puter by RS232 . During the test , the main 9 puter tell signal generator the parameters such as generative type of waveform , amplitude and frequency of waveform . Signal generator produce stipulated type of waveform and input it into the servo amplifier of the valve to be tested . During the test of dynamic characteristics , transport the produced waveform data into the mian puter at the same time for calculating dynamic characteristics . Circuit structure of the system is shown in Figure 2. current signal i ofvalve to be t es te dpressure signal 12,13, 14,15flow sign al 1 6leakage flow signal 5sinusoidal cu rr en tsignal of valve to betes tedvelocity tran sd uc er 2 0sig nalinputchammelandcon dit ion ingdatecollectcardtestingsys temdigital signal g en er at orservo amplifie r of v al ve to be testedsig nalout putchannelpressure s et ti ngdra w d yna miccharacteristics curvetest result do cu me ntand date conservation current signal of testing syste m 5. Software of testing system The main function of the software system is to plete the disposition of measured data and draw the testing curve . So the system can be divided into signal processing module , data munication module , interface management module 10 and auxiliary function modules responsible for test document processing and data storage . These modules also contain a number of submodule respectively , and then submodule call the function of basic library functions to plete their respective functions. Signal processing module is the most important module of the test system and its submodules include digital filtering, curve fitting , the difference, frequency response calculation and error pensation. Algorithms can be used by digital filtering conclude median filtering , correlation filtering , limited convergence filter