Research On Electric Wheel State Estimation And Coordinated Control Of Hub Motor Distributed Drive Vehicle

Hub motor distributed drive technology brings the potential of improving dynamics and control performance for vehicles,and has received wide attention from the automotive industry and academia.In this thesis,the optimization mechanism of distributed drive system for vehicle dynamics control is studied,and the specific system modeling and analysis,state estimation algorithm and dynamics control algorithm design and verification are completed.The thesis establishes a distributed drive vehicle dynamics model,in which a three-degree-of-freedom torsional vibration model reflecting the motion transfer characteristics from the hub motor to the tire tread is established for the electric wheel.Based on the analysis of the vehicle dynamics model,the nonlinear state observation model is built by fusing the torque and speed state information of the electric wheel.Then,the joint multi-frequency domain multi-objective state parameter observation algorithm of the distributed drive vehicle based on extended-Kalman-particle-filter is designed.The corresponding simulation test,bench test and real vehicle test are completed for the proposed vehicle driving state observation algorithm to verify the optimization of the vehicle state observation algorithm by the state observability of the electric wheel.For the dynamics control of the distributed drive vehicle,the control algorithm for steering performance and handling stability is studied.This thesis names the torque allocation coordinated control strategy that uses the electric wheel differential torque to generate steering torque for the closed-loop control of distributed drive vehicle steering as the electronic moment power steering(EMPS).The steering mechanism of the electronic differential torque is analyzed based on the steering dynamics modeling of the electric drive steering axle,and a feasible domain criterion and the control strategy for EMPS are proposed.The EMPS control is combined with direct yaw moment control to propose a hierarchical and coordinated control strategy for control allocation.Simulations and real vehicle tests verify the effectiveness of the algorithm to improve the vehicle’s low-speed steering flexibility,high-speed driving stability and steering system redundancy tolerance.This study expands the application of the electric wheel in the field of vehicle driving safety control.For high-frequency coordination control problem of the drive/brake system composed of the electric wheel system and the mechanical brake system,the coordinated control strategy of electromechanical composite braking based on model predictive control and optimal energy feedback is proposed,and the simulation verifies the improvement effect of the proposed control strategy on braking performance.Based on the advantages of the distributed drive system,an electromechanical braking system driven by high-voltage permanent magnet synchronous motor is designed and developed,and a new electromechanical composite braking system with integrated controller is proposed,which improves the control band and the braking performance of the electromechanical composite braking system from the hardware level,expands the applicable work conditions range of electric wheel regenerative braking,improveing the braking energy recovery and bringing significant dynamics performance and safety improvements to distributed drive vehicles.This study expands the application of the electric wheel in the field of vehicle braking control.