Research On Test And Evaluation Method Of Vehicle Adaptive Cruise Control

With the strong growth of the number of motor vehicles in China,the traffic safety problems caused by human factors such as overspeed driving,fatigue driving or distraction are becoming more and more prominent.Adaptive Criuse Control(ACC)system is based on the Cruise Control system,through the information detected by the workshop distance sensor to perceive whether there is a vehicle in front of the vehicle,according to the clearance between the subject vehicle and the target vehicle to replace the driver to drive or brake the vehicle.This function can relieve the fatigue of drivers in urban traffic congestion and longdistance driving on expressways,and improve highway transportation safety.At the same time,ACC System is an Advanced Driving Assistance System(ADAS)that needs to long hours of man-machine collaboration.According to the feature that drivers need to cooperate with ACC system for a long time,it can be concluded that the subjective feeling of drivers to ACC system is crucial to reflect its advantages and disadvantages.At present,professional subjective evaluation engineers with rich experience are mostly relied on to complete the subjective evaluation of ACC system.However,the evaluation studies of ACC system by large test institutions at home and abroad mostly focus on the evaluation of the objective performance of ACC system,that is,whether the performance of ACC test data meets the requirements,ignoring the subjective feelings of drivers.This paper studies the comprehensive evaluation method of ACC system,mainly including the following contents:(1)Build typical ACC system test scenarios and test methods.Based on the analysis of ACC test standards and regulations at home and abroad,this paper establishes typical test scenarios and test methods of ACC system under different operating conditions according to the test evaluation methods of intelligent connected vehicles at home and abroad and combined with the research results of Natural driving data in China.(2)Closed site test and data pretreatment.The original data of subjective evaluation and objective evaluation were obtained through the closed field test of 4 sample vehicles.Pearson correlation coefficient was used to screen the subjective score of 6 test engineers to obtain the final subjective feeling score of ACC system of each sample vehicle under various test scenarios.RT and RT-Range were used to complete the acquisition and pre-processing of objective test data,and the index curve of objective test and the value of objective evaluation index were obtained.(3)Determine the evaluation index of ACC system,and evaluate ACC system from three dimensions of safety,comfort and efficiency.AHP was used to assign weights to all indexes,entropy method was used to assign weights to the lowest indexes,and then the combination of subjective and objective weights was completed based on multiplication normalization,and the subjective and objective weights were flexibly unified.In the evaluation model,the grey comprehensive evaluation method based on grey theory is adopted.By calculating the fitting degree between the measured value and the "ideal value" of a certain car index,the grey correlation degree between the measured value and the ideal value of the sample car index is obtained.Based on this,the performance of ACC system of four sample cars is ranked.The effectiveness of the evaluation method proposed in this paper is verified by comparing the evaluation results with the subjective scoring results of testing institutions and testers.(4)Study on subjective and objective correlation of ACC system.Firstly,linear analysis of ACC system subjective perception score and objective index measurement values was conducted based on stepwise regression analysis.The objective data and subjective feeling scores which were removed from the linear equation were further analyzed by unary nonlinear regression,and the sample data were fitted by common nonlinear equations.The results show that the subjective feeling score of ACC system has a binary linear relationship with deceleration rate and headway,and deceleration rate has a more significant effect on subjective feeling.It has a nonlinear relation with deceleration.