Research On The Dynamic Performance Evaluation Of The Dynamic Test System Of The Missile-Borne Recorder And The Improvement Of The Signal-to-Noise Ratio Of The Test Signal

The dynamic test system of the missile-borne recorder is an important instrument to obtain the dynamic parameters of the projectile.With the development of science and technology,the requirements for its speed and accuracy are constantly increasing.However,the test environment for the device is extremely complex and harsh,and the signal-to-noise ratio of the test signal is low.Whether the performance of the dynamic test system of the missile-borne recorder can meet the requirements of the test requirement is one of the core issues that need to be considered,and its own dynamic performance is a key indicator of its test capability.On the premise that the dynamic performance of the dynamic test system cannot be changed,how to further improve the signal-to-noise ratio of the test signal is another important issue.Therefore,how to accurately and effectively evaluate the dynamic performance of the dynamic test system of the missile-borne recorder is a prerequisite for achieving accurate acquisition of dynamic parameters.On this basis,further improving the signal-to-noise ratio of the test signal is the key to accurate testing,and it is related to the success or failure of the test.Based on the preliminary research of the research group,this paper focuses on how to accurately and effectively evaluate the dynamic performance of the dynamic test system of the missile-borne recorder and improve the signal-to-noise ratio of the test signal,and studies the method of obtaining the dynamic parameters of the dynamic test system of the missile-borne recorder,working frequency band estimation method and test signal signal-to-noise ratio improvement method.Comprehensive research methods such as theoretical analysis and experiments have verified the effectiveness of the proposed method.On the basis of consulting a large number of documents and analyzing the research status of dynamic test technology of missile-borne recorder at home and abroad,the research methods and technical difficulties in the field of dynamic test of missile-borne recorder at home and abroad are analyzed,and the main research content and research methods are determined.The research work of this article mainly includes the following aspects:(1)In the acquisition of dynamic parameters of the dynamic test system of the missile-borne recorder,the strict coherent test conditions are difficult to meet.The FFT method has serious spectrum leakage under the non-coherent test conditions,and the sine fitting method is sensitive to the initial value of the calculation parameter.It may not converge and the signal source has a large fitting error when there is harmonic distortion.A dynamic parameter acquisition method of dynamic test system based on the separation and reconstruction of sinusoidal signal is proposed.This method can accurately separate the non-coherent sinusoidal signal,and then use the coherent sinusoidal signal to reconstruct the test signal,so as to achieve the measurement accuracy of the coherent test under the incoherent test condition.In this way,the spectrum leakage is fundamentally avoided.Because the requirement of coherent sampling is eliminated,the test device is greatly simplified,expensive equipment and tedious manual calibration are no longer needed,and the test time and test cost are greatly reduced.(2)In the working frequency band estimation of the dynamic test system of the missile-borne recorder,the actual step,impact and half-sine excitation signal are difficult to meet the requirements of the amplitude-frequency and phase-frequency characteristics of the excitation signal under the high-speed and high-bandwidth conditions of the dynamic test system.A method for working frequency band estimation of the dynamic test system of the missile-borne recorder based on the multi-frequency sinusoidal response is proposed.The failure mechanism of the high-speed and high-bandwidth dynamic test system under the actual step,impact and half-sine excitation signal conditions is analyzed.Based on the feasibility analysis of the multi-frequency sinusoidal excitation signal,a model identification algorithm based on the multi-frequency sinusoidal excitation signal is proposed.A detailed theoretical derivation and analysis is conducted,and specific formulas for parameter estimation are given.On this basis,in order to meet the needs of real-time online identification of model parameters in complex and harsh test environments,the recursive realization of the model identification of the test system under multi-frequency sinusoidal excitation signals is deduced,and the specific formulas for parameter estimation are given.Finally,the working frequency band of the test system is estimated through the dynamic test system model obtained by the identification.(3)In the complex and harsh environment of the dynamc test system of the missile-borne recorder,the collected signal,non-stationary and nonlinear,contains complex frequency components and low signal-to-noise ratio,difficult to achieve adaptive processing of test signals.The data processing method of the dynamic test system of the missile-borne recorder is studied,and an adaptive signal-to-noise ratio improvement method based on variational modal decomposition/sample entropy/wavelet analysis is proposed.The filter model is constructed,and the adaptive optimal selection of the penalty factor and the number of modes is realized by introducing the relative change rate of the center frequency and the average correlation coefficient,which improves the accuracy of the separation of the signal components;to further improve the signal noise and to ensure that the effective data is not removed,sample entropy is used to divide the signal into noise part,mixed part and trend part,and a wavelet threshold is used for the mixed part to reduce noise.Finally,the signal is reconstructed to achieve an effective improvement in the signal-to-noise ratio of the test signal.The research results of this paper have important reference significance for evaluating the dynamic performance of the dynamic test system of the missile-borne recorder and improving the measurement accuracy of the dynamic test system.