Research On Coordination Control Strategy Of Energy-Saving And ABS For 4MWIDEV

In recent years,great progress has been made in electric vehicles based on the structural modification of traditional centralized fuel vehicles.However,this kind of improvement inherits the traditional fuel vehicle chassis structure and power transmission form with power source changed,can merely improve the vehicle performance limited.In contrast,fourMotorized-Wheel Independent Drive Electric Vehicles(4MWIDEV)uses a wire control system,which integrates the drive and brake system into the wheel,and changes the structure and control of the vehicle fundamentally.As an all new vehicle structure,4MWIDEV can easily realize independent control of four-wheel driving and braking moment.Therefore,4MWIDEV has unique advantages in energy-saving control and active safety.Focusing on optimizing the torque distribution of 4MWIDEV,this paper studies the coordinated control strategy of energy-saving and ABS on the premise of ensuring braking efficiency and braking stability.The main work has been carried out is as follows:(1)Modeling and Simulation of 4MWIDEVBased on the hardware platform of the four-wheel independent driving electric vehicle of Shenzhen University,the dynamics of the 4MWIDEV and the working principle of its important components are analyzed.MATLAB/Simulink and Car Sim are used to establish the 4MWIDEV model,which includes vehicle dynamics model,driver model,motor model,on-board power battery model and electromagnetic brake model.For simulation,Car Sim benchmark vehicle is used as the contrast item.The typical vehicle test conditions are selected for simulation test,including the longitudinal ECE speed tracking test and the longitudinal-lateral coupling double lane change test.The results show that the dynamic modeling of 4MWIDEV and the verification of the Human-Vehicle-Road closed-loop control system are completed.(2)Research on Energy-saving Control Strategy of 4MWIDEV Based on Hierarchical Control FrameworkAccording to the overall structure of energy-saving control strategy for 4MWIDEV,a hierarchical energy-saving control structure framework is proposed,which includes reference speed input layer,motion tracking control layer,torque optimization distribution layer,actuator execution layer and state observation layer.Taking the optimal distribution layer of torque as the core,the objective functions of energy consumption for driving condition and braking condition of 4MWIDEV are established respectively.Moreover,relevant constraints such as ECE regulation,maximum torque of motor and battery charging state during regenerative braking are taken into consideration,so that the equations and inequalities are established.The optimal solutions of front and rear axle driving and braking distribution coefficients are obtained respectively by genetic algorithm and finite cycle interpolation method.Then,based on the factors affecting the actual operating conditions of automobiles,the corresponding correction strategies for battery SOC and vehicle speed are formulated.For simulation and verification,three different braking intensity conditions,typical cycle conditions NEDC and UDDS,are selected to carry out simulation tests by comparing with the traditional torque distribution strategy.The effectiveness of the energy-saving control strategy based on Hierarchical Control Framework for 4MWIDEV is verified.(3)Study on ABS Control Strategy Based on Optimal Slip RateFirst of all,the composition and working principle of hydraulic ABS are analyzed.Then,the traditional hydraulic ABS and electromagnetic mechanical ABS are compared from three dimensions: structure,control objectives and control methods.According to the structure of electromagnetic mechanical ABS,the on-line recognition system of road type and the ABS sliding mode control system based on 1/4 vehicle dynamics model is built.For simulation,the performance of sliding mode controller and PID controller applied in ABS,and the braking performance of ABS based on optimal slip rate control and fixed slip rate control were both compared under the conditions of high adhesion road,low adhesion road and opposite roads respectively.(4)Design of coordinated control strategy between regenerative braking system and ABS.Combined with regenerative braking control strategy and ABS control strategy of 4MWIDEVs,based on hierarchical control structure,ABS with sliding mode controller is embedded in braking system of the vehicle model.And then,regenerative braking torque is planned by braking intensity and slip rate.The coordinated control strategy of ABS for electromagnetic brake coupled regenerative braking system under emergency braking condition is designed and simulated on high and low adhesion road.