Research On Trajectory Tracking And Stability Control Strategy Of Distributed Drive Intelligent Vehicles

With the increase in car ownership,problems such as traffic safety,energy crisis and environmental pollution have become increasingly significant.The electrification and intelligence of automobiles is an effective way to solve the above problems.Among them,the independent drive of each wheel of distributed drive intelligent vehicles is an ideal carrier for intelligent driving technology and active safety control technology,and has become an important direction for future automobile development.However,as one of the core links of intelligent driving technology,the research on trajectory tracking control lacks comprehensive consideration of factors such as multi-source uncertainty of vehicle systems and driving safety under complex working conditions such as high speed and low adhesion road surface.Therefore,this paper proposes a cooperative control strategy for trajectory tracking and sideways stability for distributed driven intelligent vehicles.This strategy makes full use of the chassis advantages of distributed drive,combines intelligent driving motion control with direct swing torque control technology,and aims to improve the trajectory tracking accuracy and driving stability of vehicles under complex working conditions.Defines the three coordinate systems that need to be used for the study.Considering the characteristics of distributed drive intelligent vehicles,a seven-degree-of-freedom vehicle dynamics model including vehicle dynamics model,wheel model and nonlinear tire model is established.In order to facilitate theoretical analysis and control algorithm design,the highdegree-of-freedom model is simplified and decoupled,and the horizontal two-degree-offreedom dynamic model and longitudinal dynamic model are established respectively,and the feasibility of the simplified decoupled model is verified and analyzed.Aiming at the problems of strong coupling and multi-source uncertainty in the process of vehicle trajectory tracking,a trajectory tracking control method based on constraint following is proposed.In terms of lateral path tracing control,the equation constraint is constructed according to the path tracing kinematic relationship,the path tracking robust controller is designed based on the constraint following method,and the parameter selection of the adaptive law is optimized.According to the equation constraint of longitudinal motion control scene,the direct control structure is adopted to view the uncertainty such as wind resistance in longitudinal speed control,and the longitudinal speed robust controller is designed based on the constraint following method.Aiming at the problem of poor stability of vehicles under complex working conditions,a hierarchical control architecture of horizontal swing stability is proposed.On the basis of the nonlinear vehicle dynamics model,the unscented Kalman filter algorithm is used to estimate the key state parameters of the vehicle,and the stable domain boundary of the vehicle is determined by the phase plane theory.The expected control parameters are calculated by the linear two-degree-of-freedom dynamic model,and the direct yaw moment upper controller is designed based on the improved sliding mode control algorithm.A lower layer allocation algorithm based on quadratic programming is designed to meet the additional yaw moment and longitudinal dynamics requirements required by the upper layer.A joint CarSim-Simulink simulation platform is built to simulate and verify the proposed trajectory tracking and stability cooperative control strategy.The simulations were conducted under three conditions: high-speed high coefficient of adhesion road,medium-speed low coefficient of adhesion road and variable-speed high coefficient of adhesion road.The simulation results show that the proposed control strategy can make the vehicle combine excellent trajectory tracking accuracy and driving stability under various complex working conditions.