Research On Vehicle Road Surface Adhesive Condition Identification Approach

With the rapid development of automobile industry and the increasing automobilequantity as well as the declining of driver’s manipulation skills, more accidents and casualtiesare caused by traffic transportation. In order to reduce the occurrence of traffic accidents, inrecent years, many car companies and scientific research units begin to study automobile activesafety control technology, which is gradually applied in the actual vehicle. The main controlobjective of automobile active safety control technology is to regulate the tire forces betweentyres and road surface, which are restrained by road adhesion conditions. Road surfaceconditions not only affect vehicles’ acceleration performance, braking performance, but alsoinfluence on the handling stability of the vehicle, so how to identify the adhesive conditionbetween vehicle and road accurately and effectively is the key factor of various automotiveactive safety control system control strategy. In order to make full use of the maximumadhesion conditions on different roads for the use of active electronic control system, it isnecessary to identify the current road on which a vehicle travel and regulate the control targetof controller in real-time based on the identification results.The domestic and foreign research on road surface condition identification is developedmostly on straight road, which has not taken into consideration of the influence of roadroughness on identification parameters. In this paper, having considered the influence of roadroughness and dynamic loads on the identification algorithm, a road surface conditionidentification approach is proposed on the basis of “road surface characteristic value withoutunit” with the application of two kinds of typical tire models (Burckhardt and Kiencke), androad surface characteristic value threshold on6typical roads is calculated,which representsthe closed area under the segment of road friction coefficient-slip ratio curve before optimalslip ratio, according to Burckhardt and Kiencke road-tire mathematical model, and6kinds oftypical road surface characteristic intervals are defined based on these typical roadcharacteristic value thresholds mean value. The identification is finished according to the roadcharacteristic value interval in which estimated real-time value falls during braking process,and real-time estimation of the current road peak friction coefficient and optimal slip ratio iscompleted in accordance with this method. In order to consider the influence of roadroughness on the identification approach, the road surface characteristic intervals are modifiedbased on14-DOF vehicle simulation platform on C grade road surface to improve therobustness of the method proposed on uneven road surface.The14-DOF vehicle dynamics model is built,14degrees of freedoms involve vehiclebody longitudinal, lateral,vertical,yaw, pitch and roll motion as well as vertical and rotational motion of four wheels, and vehicle simulation model is built by MATLAB/Simulink software.Braking simulation tests are conducted on all kinds of single typical road surface and varyingroad surface as well as uneven road respectively, the simulation results of typical roadcharacteristic value without unit, identified road condition, real-time slip ratio, adhesioncoefficient are given, which show that the identification approach can identify the currentroad rapidly and accurately. The bench test results from a braking test data on the self-madeABS test-bench further verify the feasibility of this approach.The research results show that the proposed road identification method can beconveniently used in the optimal slip ratio control of vehicle electronic control brake systemand active safety control system, which can improve vehicle active safety. However, roadsurface identification for the combined condition and how to improve the reliability of theidentification algorithm in the actual controller are still major problems.