Design And Implementation Of An Automobile Multi-functional Tester Based On USB Data Acquisition Card

As an important output source of automobile power,the performance of the engine determines the overall quality of the automobile to a certain extent,so it is particularly important for engine parameter detection and fault analysis.With the deepening of the information age,various instruments and equipment continue to develop in the direction of intelligence,diversification of functions,and portability,which also put forward higher requirements for automotive testing and analysis.In order to meet the automotive vibration signal processing,analysis and performance parameter testing,a mixed programming technology of Matlab and Delphi is used,and based on the virtual instrument technology,an automobile multi-functional tester is realized by using Matlab and Delphi mixed programming technology based on USB data acquisition card,which possesses such functions like eight-channel signal data acquisition and storage,signal processing and analysis.Using Delphi programming,the human-computer interaction interface was written,which realized the eight-channel large-capacity uninterrupted acquisition,real-time signal value and waveform display;the data ring buffer class was customized in the programming to ensure the reading and writing of data inerrably;use multi-threaded programming to improve data processing capabilities;using the Component Object Model(COM)technology,the program can be compiled to generate a dynamic link library file(Dynamic Link Library,DLL),on the Delphi platform,DLL files are installed and called,and nearly 30 signal analysis and processing methods are realized with the help of Matlab’s powerful function toolbox.The use of Matlab and Delphi mixed programming technology enhances the analysis and processing capabilities of the automobile multi-functional tester,and it’s very convenient for function extension.In order to complement the advantages of different analysis methods,several time-frequency combination analysis methods are proposed,such as t EMD(Empirical Mode Decompositio)-FFT(Fast Fourier Transform),Wavelet decomposition and FFT,Wavelet noise reduction and FFT,EMD-WVD(Wigner-Ville Distibution),EEMD(Ensemble Empirical Mode Decomposition)-FFT and other time-frequency combination analysis methods.Its combination not only expands the time-frequency analysis method,but also makes it more accurate for signal analysis and processing.Through the detection and error analysis of the sensor of the Passat full-vehicle electrical training platform,the analysis of the simulation signal and the field test engine vibration signal and the use of various methods for analysis,through analysis and verification,it has a good collection and analysis of the unstability signal,the results verify the reliability and practicability of the automobile multi-functional tester.The tester can also be applied to the vibration signal acquisition and processing of mechanical equipment and the diagnosis of fault diagnosis.