| With the increasingly vigorous development of the infrastructure industry,the field of construction vehicles has attracted more and more attention from infrastructure practitioners.Since the working environment of engineering vehicles is outdoors,and outdoor operations will inevitably encounter harsh environments such as extreme cold,high temperature,dust,vibration and electromagnetic interference.This special working environment will cause frequent failures of the CAN bus of the electronic control unit of the engineering vehicle,which will lead to communication failure and affect the normal operation of the vehicle.This essay is based on the horizontal subject and the specific requirements put forward by the enterprise,the requirements of enterprise is judging the CAN bus physical link failure when the engineering vehicle cannot communicate normally;positioning and analyzing the CAN bus electromagnetic interference in the electromagnetic interference environment.This essay main contributions are as follows:1.Aiming at the problem of the failure of the CAN bus physical link of the engineering vehicle electronic control unit that causes the data to be unable to be transmitted normally,this essay analyzes the causes of the common failures of the physical link and divides them into seven types of failures.By summarizing the characteristics of these seven types in failures in terms of voltage difference,a method of CAN bus physical link fault diagnosis based on voltage difference is proposed.We built a physical link detection experimental environment,implemented the algorithm based on virtual instruments,and passed physical and simulation experiments.A total of seven hundred experimental data are collected for seven types of failures,and the experimental analysis shows that the average accuracy of the method can reach 92%.2.Aiming at the problem of abnormal CAN bus data transmission in engineering vehicle nonpublic CAN messages in the electromagnetic interference environment,this essay research the electromagnetic interference characteristic parameter extraction method,and judges whether there is electromagnetic interference through wavelet analysis,wavelet packet decomposition and interference characteristic parameter extraction.Then a CAN bus electromagnetic interference location algorithm based on runt pulse search is proposed,which can locate the position of electromagnetic interference in CAN frames.Through experimentation,the accuracy rate of BEILRPS algorithm using custom threshold can reach 85.5%,and the accuracy of BEIL-RPS algorithm using average threshold can reach 90.5%.3.According to the above two algorithms,this essay has developed a virtual instrument-based CAN bus detection software system for the electronic control unit of an engineering vehicle,and developed a prototype of the CAN bus detection instrument.The software system mainly includes the function of physical link fault detection and the function of locating interference points under electromagnetic interference and so on. |
