Development Of Real-Time Signal Acquisition System On The New Compression Ignition Device

In this paper,in order to study the characteristics of Homogeneous Compression Combustion Ignition(HCCI),on the basis of the new compression combustion device,a real-time signal acquisition system for displacement signals and cylinder pressure signal was developed combined with the experience by our research group to promote the research in this field.The main works in this paper include:In order to realize the correspondence between cylinder pressure and piston rod displacement,on the basis of the original device,the displacement measuring mechanism of piston rod was designed.The linear motion of the piston displacement is converted into the rotational motion of the final gear by means of the overextension gear and rack increasing mechanism,and the displacement signal is transmitted by the photoelectric switch.This design ensures the original cylinder structure and the accuracy of displacement conversion.According to the characteristics of cylinder pressure sensor signal,a two-stage amplification and filter conditioning circuit with adjustable small signal gain was developed.The frequency response characteristics of the circuit are verified by theoretical calculation and simulation analysis.And then,the real-time signal acquisition system was completed based on STM32.And then,in order to meet the needs of external trigger real-time signal acquisition,A/D conversion and serial port communication program design were designed on the embedded system.At the same time,in order to realize the real-time monitoring of the collection results,the program based on MFC is written on the PC to realize the function of serial port communication,drawing and saving data points.According to the characteristics of the periodic fluctuation of the noise signal of this sensor,the side lobe cancellation concept commonly used in the field of military radar and antenna was introduced,and two interference cancellation schemes of periodic noise signal were put forward.Then the typical solution for the periodic fluctuation of the noise signal was concluded.Finally,in order to verify the functions of each part of the system,along the signal data was the system tested flow step by step.The results showed that: the signal data in A/D conversion and serial communication parts had high conversion accuracy and transmission stability.Then,the overall low and high frequency trigger test were carried out.The results showed that the data acquisition accuracy and sampling frequency of the developed real-time signal acquisition system would meet the acquisition needs of the research object.