Research On Driving Stability And Control Technology For Coach Bus In The Extreme Turn Conditions

The condition of extreme turn for coach bus are the special driving conditions,which are affected by the “driver-vehicle-road”.The bus is prone to rollover or sideslip under extreme turn condition which is driving or turning too fast,thus causing traffic accidents.The driving stability and its control of the coach bus under extreme turn conditions being taken as the research object,the formation of the extreme turn conditions of the coach bus,the main related factors and the mechanism of action of the driving stability under extreme turn conditions,the evaluation and the integrated control of the driving stability under extreme turn conditions,the stability integrated control network and the application layer protocol based on CAN are deeply studied,which provide solutions to the active safety control of the coach bus.The main research work of this paper are as follows:(1)The extreme turn conditions and the concept model of the coach bus are put forward by analyzing the influence law of the “driver-vehicle-road” on the driving stability of the coach bus under extreme turn conditions and by studying the formation mechanism of the extreme turn conditions.Based on the research of the main related factors and the mechanism of action of the driving stability under extreme turn conditions,the correlation model of the stability influence factors of the coach bus under extreme turn conditions is built,and is taken as the theoretical basis for the analysis and evaluation of the driving stability of the coach bus.(2)Through the analysis on the steering state and the center of mass motion of the coach bus,based on the classical theory of the vehicle dynamics,the main force and the motion status of the coach bus under extreme turn conditions are analyzed,the dynamic equations of the motion status of the coach bus under extreme turn conditions are built,the real vehicle road test and the vehicle dynamics simulation software IPG TruckMaker are adopted to simulate and have a comparison,the effectiveness and the correctness of the dynamic equations are verified.The results show that it can describe the driving state of the coach bus under extreme turn conditions,and can be used for the simulation and verification of the driving stability control of the follow-up coach bus under extreme turn conditions.(3)The lateral force coefficient method and the calculation formula of the coach bus driving stability control under extreme turn conditions are put forward by analyzing the relationship between the lateral force coefficient and the driving stability when the coach bus is steering.The calculation methods of the early warning threshold and risk threshold of the lateral force coefficient of the coach bus under extreme turn conditions are built based on the analysis of the lateral force coefficient by the methods of data analysis and simulation experiment.The safe turning radius calculation model and the safe speed calculation model of the coach bus driving stability are established based on the lateral force coefficient,and the computation model is verified through the method of simulation comparison.The model can well reflect the characterization on the safe turning radius and the anti-rollover safety speed of the coach bus under extreme turn conditions.(4)Based on the analysis of the control characteristics of the two driving stability control methods,which are the active steering adjusted the tire lateral force and the yaw moment produced by the differential braking control adjusted longitudinal force,the control strategy and the control algorithm,the control process and the control mode switching algorithm of the active turning control,the differential braking control and the integrated control under extreme turn conditions are put forward,thus meeting the driving stability control requirements of the active safety and the auxiliary driving.The driving stability integrated control network and the application layer protocol under extreme turn conditions based on CAN is designed.(5)The driving stability integrated control hardware in loop simulation test platform of the coach bus under extreme turn conditions is built by using the IPG TruckMaker dynamics simulation system,the Matlab/Simulink simulation software,the coach vehicle network experiment platform,the active steering,and the pneumatic differential braking actuator.By the verification of the hardware in loop simulation on the driving stability integrated control method and control network,the control method has good control performance,and the performance of the control network can fully meet the requirements of the control system.The paper provides a theoretical basis for the development of the active safety control,the auxiliary driving and the automatic driving,thus greatly enhancing the independent innovation ability of the active safety control technology of the coach bus of our own country.