With the progress of vehicle intelligence and integration,steering-by-wire(SBW),as a new steering technology,has drawn more and more attention.Compared with the traditional mechanical steering system,the steering-by-wire system has many advantages,including simplifying the steering system structure,Improving the utilization rate of cab space,and facilitating the combination with advanced technologies such as automatic driving.Although there are many advantages of steering-by-wire system,there are still some key problems to be solved.In traditional vehicles,drivers can acquire road feedback information through mechanical connection of steering system,namely "road sense".However,because the peculiar structure of SBW cannot obtain road sense directly,it needs power components to generate road sense.In order to solve the problem that the road sense can not be acquired in the SBW system,this paper studies the key technology of road sense simulation.Firstly,the structure and working principle of the SBW system are analyzed,and the dynamics model of the steering wheel assembly is established.In addition,the lateral characteristics of the tire were added to the linear 2-DOF vehicle model.Combined with the "magic formula" tire model,a nonlinear 2-Dof vehicle model with certain accuracy under large lateral acceleration was established,which laid a foundation for the study and simulation of the upper level road sense planning.Secondly,in the study of upper road sense planning,two kinds of road sense planning schemes are proposed.In the mechanical road sense scheme,the vehicle modelbased method is used to calculate the road sense,and the influence of the traditional vehicle steering assist on the steering wheel feedback torque is considered,so that the driver can acquire the road sense similar to the traditional vehicle.In the scheme of driver preference road sense,combined with the efficient nonlinear fitting ability of neural network algorithm,the driver preference road sense model was established to calculate the driver preference road sense for the vehicle with SBW.At the same time,the simulation model of mechanical road sense and driver preference road sense simulation strategy is established in the simulation software,and the feasibility of the two road sense schemes is preliminarily analyzed through simulation.Finally,in the study of the control strategy of the lower level road sense motor,the design of the road sense motor control system based on permanent magnet synchronous motor(PMSM)is completed,including the establishment of PMSM model,the research of vector control algorithm and the research of the current dynamic decoupling control strategy based on active disturbance rejection control(ADRC).The simulation results show that the torque and position control performance of the road sense motor under the control scheme are preferable.In order to further verify the feasibility of road sense simulation algorithm and road sense motor control algorithm,the controller of road sense simulation system is designed based on STM32 single chip microcomputer.Then,the embedded automatic code generation technology is used to download the algorithm to the controller,and the off-line test of the road sense simulation system is completed,which verifies the rationality of the designed algorithm and controller. |