Research On Active Lane Changing And Driver-machine Shared Control Of Intelligent Vehicle Based On Steer-by-wire System

As an advanced technology of automobile chassis control,wire steering system breaks the structural constraint of traditional steering system and promotes the development of vehicle automation and intelligence.In this thesis,the active lane changing and drivermachine shared control of intelligent vehicles are studied on the design platform of steerby-wire.Firstly,the structure and working principle of the steer-by-wire system are introduced in detail.According to the particularity of the system structure,the variable transmission ratio is established,and the steady state steering gain is taken as the starting point to realize the stable feedforward control of steering wheel to vehicle steering instruction control.Aiming at the steering force feedback control of the steer-by-wire system,a steering resistance moment model satisfying the driver’s virtual hand feeling is designed.The reference model and Car Sim vehicle model system are established as the control object.Then through the verification of road feeling simulation by using Car Sim/Simulink co-simulation model,it establishes the foundation for the research and analysis of driver’s shared control of steer-by-wire system.Secondly,the active lane changing control is studied.Considering the vehicle driving conditions and road environment information,a method for longitudinal and lateral cooperative trajectory planning for lane change trajectory is designed suitable for curved road.By establishing a vehicle system control model,a backstepping sliding mode trajectory tracking controller based on Lyapunov’s stability principle is adopted.Combined with Car Sim and Simulink for simulation verification,the effects of trajectory tracking control under different curvatures are analyzed and compared with traditional tracking control methods.In addition,for the driver intervention control in the process of vehicle lane changing,a driver authority dynamic allocation control strategy is proposed.The vehicle safety evaluation coefficient is established based on the vehicle-road position information and the vehicle state,the driver’s operation intention evaluation coefficient is established based on the difference between the driver’s and the automatic control system’s control intention,then the fuzzy logic control is introduced to dynamically allocate the driving authority coefficient.According to the controlled state of the vehicle,the control mode of the road feeling motor is designed,and the driver’s intention is warned when the road feeling motor uses the force feedback function of the driver to the driver-machine shared control.And through simulation to verify the effectiveness of the man-machine shared control system designed in this thesis.Finally,in order to verify the effectiveness of the control strategy involved,a hardwarein-the-loop test bench was built according to the structure of the steer-by-wire system.By testing the hardware and software of the test bench,the steering angle following and road feeling tests were conducted to verify the established test bench.The hardware-in-theloop simulation of the active lane changing control and driver-machine shared control proposed in this thesis is carried out,and the test result verify the effectiveness of the active lane change and driver-machine shared control of the steer-by-wire vehicle.