| The hydraulic actuator is the key actuator of the electro-hydraulic servo system,and its performance directly affects the operation of the electro-hydraulic servo system.As one of the main performance indicators of hydraulic actuators,the frequency response characteristics have an important impact on the application of hydraulic actuators.Therefore,it is necessary to study the frequency sweep test system of hydraulic actuators to test the frequency characteristics of the actuators,in order to improve its practical application in hydraulic system.The main research content of this paper is as follows:First of all,this paper determines the overall scheme of the hydraulic actuator frequency sweep test system,which is mainly divided into three parts: excitation signal source,data acquisition and algorithm processing.For the excitation signal source,a lowpass filter and a power amplifier module are further designed to improve the spectral purity and driving ability of the output signal,so as to realize the design of the hardware related to the excitation signal source of the frequency sweep test system.The DDS module is designed based on FPGA and DAC,and the program design of single-point,linear and logarithmic sweep sinusoidal signals is completed,and use Model Sim software to simulate DDS modules to verify the correctness of the program design of sinusoidal signal excitation source.The design of the synchronous acquisition module,frequency division module and command control module of dual-channel analog is realized,and the ILA test of the command and control module is carried out to verify that the instructions can be transmitted reliably.Then,according to the UDP communication protocol of the lower computer,the development of the upper computer software is developed based on Py Qt to realize parameter setting,data processing and acquisition waveform display functions.An amplitude calculation method based on sinusoidal signal sampling value is proposed,and when the sampling frequency is much greater than the sinusoidal signal frequency in the initial phase of any sinusoidal signal sampling,the amplitude error rate is approximately satisfied with the derived amplitude error rate range,and the error rate range is only related to the number of full waves sampled.Finally,the excitation signal source and data acquisition processing function of the sweep frequency test system are verified,and the proposed sinusoidal signal amplitude calculation method is verified.The circuit simulation system was constructed,the frequency sweep test was carried out,and the amplitude-frequency characteristics obtained by the experiment were compared with the ideal amplitude-frequency characteristics,and the curves were basically consistent,and the gain error was within 1d B,which verified the accuracy of the sweep test system.The test system of hydraulic pressure cylinder was built,and the amplitude-frequency characteristics obtained by experiment and the amplitudefrequency characteristics obtained by modeling were compared,which further explained the effectiveness of the sweep frequency test system. |
