Research On Virtual Test Technology Of Key Performance Of Passenger Vehicle Based On Semi-physical Simulation Drive

Automobile test plays a very important role in the development of new automobile models,especially a large number of real vehicle tests are needed for the finalization test after the design of sample vehicles,consuming a lot of human,financial and material resources,prolonging the development cycle and indirectly reducing the market competitiveness of the new-type vehicles.Meanwhile,according to the relevant statistical analysis,the essential safety problems of the commercial vehicles especially the passenger vehicles are the main inducement of the traffic accidents with mass death and injury,moreover,the structure safety performance of vehicles are the dominant factors that supports the safe running of the passenger vehicles.With the rapid development of the computer science and technology,and the continuous development of the automobile product research digitalization,fully digital simulation of the vehicle performance test is one of the main development trends.However,the traditional vehicle virtual simulation test systems have many problems,such as high cost and too large and complex systems.Therefore,the research on the virtual test technology of key performance of passenger vehicles will have important practical and far-reaching social significance to improve the quality and efficiency of the development of the new passenger vehicle models.Based on the project of the national natural science foundation of China(51278062)and the natural science foundation of Shaanxi Province(2018JQ5142),the paper applied a combination of man-machine engineering,systems engineering,vehicle system dynamics,artificial intelligence,optimization theory,signal processing technology,virtual test technology and intelligent evaluation technology.Through a lot of theoretical analysis,modeling algorithm,program design,and off-line simulation,the key technologies such as real-time virtual test of passenger vehicle performance,timely evaluation and optimization of vehicle design parameters was analyzed,and the low cost,portable and personal aided design platform system was finished.Aiming at the technical problems of non-real-time vehicle operation information collection,and simple and equivalent vehicle operation parameter model construction,the multi-core and multi-thread method was adopted to carry out the research on real-time parallel operation information collection and fine refinement of vehicle operation parameter model construction.Through the hardware construction of line displacement sensor,angular displacement sensor,micro switch and optocoupler isolation module,the preliminary acquisition and calibration transformation of vehicle control information data were carried out.Based on the improved variable step LMS algorithm,the collected data could be cleaned by adaptive filtering,clutter interference could be suppressed,and the efficiency of information collection could be improved.Through adopting the shared cache on a multi-core architecture,building the parallel real-time sampling framework of condition variables synchronous between multi-threads,driving operation information “acquisition-processing-transmission” seamless connection was realized by using level tasks in parallel mode,which saved time consumption of the function switching during the program execution,achieving the effect of real-time driving operation information collection and transmission with low cost and high parallel.Considering the physical structure characteristics and power transmission characteristics of vehicle power system,transmission system,steering system and pneumatic braking system,a detailed model of vehicle operating parameters was established to realize the accurate transmission of vehicle operation information to vehicle operating parameter information and improved the effectiveness of the vehicle dynamic model parameter input.Aiming at the hysteresis problem of the traditional vehicle dynamic model,the improved fourth-order RTRK real-time algorithm and the template technology was adopted to study the real-time solution of the vehicle dynamics model.The boundary of the vehicle dynamic model was narrowed by setting up the constrain condition of the vehicle dynamic model,and the corresponding dynamic model of the vehicle was constructed based on the force analysis of the three-dimensional vehicle dynamic model with multi-angle.Based on the comparison between the tire rolling mechanics model and the mainstream tire model,the improved Gim model was used to construct the tire ground mechanics model,which effectively analyzed the tire mechanics characteristics under the changing of tire force and structural parameters,and then accurately described the vehicle running posture during the driving process.Through the standardization transformation of vehicle dynamics equation expression,the simulation time region was discretized according to a certain step,and the fourth-order improved RTRK algorithm was selected to carry out the real-time calculation of vehicle dynamics equation,so as to reduce the workload of integral operation subroutine.The solver of the vehicle dynamics equation was packaged through the template technology based on C++,and the expression of the vehicle dynamics equation was passed as a function parameter.The corresponding calculation example was formed during the compilation process,avoiding the time overhead caused by the expression object load,thus the code reusability was improved,and the real-time calculating optimization of the vehicle dynamics equations was completed.The co-existence problem of real-time and robustness of the numerical algorithm was solved,and the simulation of the vehicle test condition with low time consumption and high precision was realized.Aiming at the problem of various representational physical indexs of the vehicle key performance and the single function of the traditional vehicle performance evaluation method,the technology of the key performance evaluation of the vehicle was studied depending on the improved radar map theory.Based on the 3DMax polygon modeling technology,mapping technology and polygon smoothing group technology,the test vehicle and test environment were built combined with the reference to the template and the extended library,and then,the real-time roaming of 3D experiment scene was realized by calling the OpenGL matrix stack.According to the methods of the vehicle tests developed by the national standards and ECE regulations,the representational physical index program set of the vehicle critical performance was bulit.Through improving the traditional radar map evaluation method,the target layer,criterion layer and index layer of the analytic hierarchy model of the vehicle key performance were constructed using the evaluation feature vectors of the sector area and sector circumference with the combination of qualitative and quantitative methods.The weight of the evaluation indexs were determined by judgment matrix,the evaluation indexes with different dimensions were normalized,and the area and circumference of the evaluation object were selected as the evaluation eigenvectors calculating by the index weight and evaluation value.Finally,the evaluation of the vehicle key performance was finished according to the constructed evaluation vector and the analytical value of the constructor,which improved the effectiveness and practicability of the vehicle critical performance evaluation,and facilitated the improvement and the optimization of the designe parameters of the vehicle.In order to verify the effectiveness and real-time performance of the proposed algorithm,the virtual test system of the key performance of the passenger vehicle was bulit and the function of the system was realized.The key performance virtual test of the passenger vehicle was completed based on the popular vehicle of the market,meanwhile,the test results were analyzed and intelligently evaluated,and the vehicle design parameters were optimized.The test results showed that the proposed virtual test scheme for key performance of passenger vehicle combined with personal assistant control was effective and feasible.The system was convenient to use,low in cost,stable and reliable in work,and met the application requirements of personal assistant design of vehicle design engineer.