Research On Functions And Algorithms Of Active Rear Wheel Steering And Full Active Four-wheel Steering Control

With the continuous development of human society and the continuous update of automobile technology,people have higher and higher requirements for the stability of the car’s operation.The active steering technology born from this makes the car more flexible and stable during the turning process.This article mainly focuses on active steering technology,including active rear-wheel steering,full-active four-wheel steering strategy research with integrated front-wheel steering by wire,and the establishment of the mass center slip angle estimation module.Simultaneously,simulation experiments and benches are carried out for the response strategy.The hardware-in-the-loop experiment mainly includes the following aspects:(1)Design an active rear-wheel steering control strategy.Based on the linear two-degree-of-freedom vehicle model,consider the non-linear characteristics of the vehicle tires,combined with the optimal control theory,and design the variable weight coefficient active according to the non-linear characteristics of the tires.The optimal controller for rear-wheel steering,and a brief introduction to the active rear-wheel steering proportional control,is used for the control experiment of the control strategy simulation experiment.(2)Design a fully active four-wheel steering control strategy with integrated front-wheel steering by wire.Propose a suitable vehicle ideal reference model,and take the steady-state value of reducing the side slip angle of the center of mass and the steady-state value of the yaw rate tracking the ideal reference model as the control targets,and design the optimal control of all-active four-wheel steering based on the optimal control theory.It analyzes the discrete-time optimal control,designs the Riccati equation solver based on the iterative method of the discrete Riccati equation,and makes corresponding simulation experiments.(3)Through simulation experiments,it can be seen that proportional control,full-active four-wheel control,and active rear wheel optimal control strategies can all achieve the goal of compressing the side slip angle of the center of mass,but the full-active four-wheel control strategy can also perfectly track the ideal Yaw rate.(4)A nonlinear full-dimensional state observer is built based on the vehicle dynamics model and tire model to estimate the vehicle’s center of mass slip angle,and the corresponding simulation experimental conditions are designed to analyze the estimation effect.The experimental results show that the center of mass slip angle is between conventional and Good estimation results are achieved under extreme conditions.(5)By building a hardware-in-the-loop simulation platform,for the four-wheel steering control strategy designed in this paper,under the set working conditions,the hardware-in-the-loop simulation of the control strategy is completed,which verifies the effectiveness of the algorithm.