Study On Several Key Technologies Of Steering Operating Svstem In Vehicle Simulator

The system formed by driver and vehicle is a kind of closed loop control system, called human-vehicle closed loop system (HVCLS). At present, most theoretical research on steering operating system of HVCLS is done by numerical simulation, due to driver’s feeling, judg-ment and action is difficult to describe completely by mathematical model, numerical simula-tion with driver model takes less consideration of human factors, so it is less effective and li-mited in some range. Directly using real vehicle experiment has some disadvantage on high cost, long cycle, limitation of ground and weather, safety problem, pollution of environment and so on. Therefore, driver’s online experiment in vehicle simulator is an effective way to study steering opearting problems of HVCLS. Combined with research project of MME that our group undertake, on the basis of developing a high fidelity vehicle simulator, key points of this paper are focus on steering wheel torque simulation and changeable steering ratio control method about steering operating system, experimental study is carried on vehicle simulator in different working condition, some analysis and evaluation is made with experiment result. Research result of this paper can provide certain guidance of real vehicle steering operating system design.Firstly, the features and key technologies of semi-physical vehicle simulator with6de-grees freedom of motion platform is described, which can provide a platform for further simu-lation and experiment. The function of steering operating system is analyzed, hardware struc-ture and processing procedure is designed. Based on above content, three research aspects of steering operating system are proposed.Secondly, the theoretical model of steering operating system is established, some simpli-fication are made according to its working condition of low frequency and locked rotor, sys-tem identification test is set to get the transfer function of steering operating system, frequency response characteristic is analyzed. This transfer function is used in SIMULINK to get torque output, compared with actual test torque output, two outputs are very close, the result indicates that applying this transfer function to control motor to generate required torque is feasible, the designed steering operating system meets the requirement of vehicle simulator experiment. Then, the relation of steering wheel torque and vehicle state parameters is analyzed, the range of steering wheel torque is confirmed. A steering wheel torque simulation control me-thod for vehicle simulator is proposed. Vehicle vertical state, road contact property, speed, steering angle and lateral acceleration is all taken into consideration. Each state parameter controller is simulated in SIMULINK. This method is set to steering operating system and ve-hicle simulator experiment is made. The result indicates that torque generated by this method can well present vehicle state change and let driver know it more clearly and completely.At last, a changeable steering ratio control method based on steering operating system is studied. The realization form and control principle of changeable steering ratio system is simply introduced. A fuzzy control changeable steering ratio feedback method is described, fuzzy controller of changeable steering ratio and yaw rate feedback factor is designed, simula-tion result shows that effect of two controllers are obvious. This method is taken to steering operating system, double shift line, serpentine and steering transient response experiment is set in vehicle simulator. The human-vehicle comprehensive performance index (HVCPI) of this method and const steering ratio is compared. Further discussion of two different weight selec-tion including vehicle stability and trajectory tracking accuracy is made to evaluate experiment result. The above experiment result all indicates that this method can reduce the burden of driver and optimize vehicle stability at the same time, HVCPI is improved significantly, this method is feasible and worthy for application.