Study On Adaptive Cruise Control Of Four-Wheel Independent Driving And Steering Electric Vehicle

The development of vehicle adaptive cruise control is based on traditional constant speed cruise control.According to the relative distance between the vehicle and the front target vehicle or obstacle,the vehicle driving or braking is automatically controlled to ensure the appropriate safe distance.The four-wheel independent driving and steering electric vehicle is selected as subject,the adaptive cruise control,regenerative braking control and rear wheel active angle control are studied,taking advantages of its four wheels drive torque,brake torque and four wheels angle can be controlled independently based on the National Natural Science Foundation of China “Study on dynamics control for four wheel independent driving and steering electrical vehicle considering driver characteristic”(No.51675257).On the premise of make sure adaptive cruise control,the electric power can be saved by regenerative braking control.Additionally,the driving comfort and handling stability of electric vehicles can be improved by the rear wheel active angle control.First of all,a simulation model of four-wheel independent driving and steering electric vehicle is conducted.According to the parameters of four-wheel independent driving and steering electric vehicle,the model of the four-wheel independent driving and steering electric vehicle simulation is established,and the CarSim software is combined to simulate the designed model,which proves the rationality of the model.What's more,a strategy of adaptive cruise control(ACC)is designed,which consider the mode switching control of the difference of theoretical safety distance and the actual distance as well as the relative speed between two cars and regenerative braking.The ACC system is divided into following vehicle,constant speed cruise and uniform speed mode by the control strategy.Furthermore,the adaptive cruise controller is designed including the algorithm of theoretical safety distance,driving torque control and braking torque control.In addition,take advantages of four-wheel independent driving and steering electric vehicle,the regenerative braking control is used in order to retrieve the energy which consumed during the process of braking,therefore,the energy consumption of the electric vehicle is saved.The combination of MATLAB/Simulink and CarSim software is used to verify the control strategy by simulation experiments.Moreover,the strategy of active rear wheel steering is designed.The linear two degrees of freedom vehicle model is selected as the reference model,the additional rear wheel angle decision controller is designed based on the optimal control theory.When the vehicle's mass side slip angle and yaw rate exceed the expected value calculated in the reference model,the additional rear wheel angle decision controller will control two rear wheels to generate a certain rotation angle.Therefore,it improves the handling stability of the adaptive cruise control process.Finally,the adaptive cruise control strategy with rear wheel active steering control is tested and verified based on the driving simulator experiment platform.The whole vehicle model of the driving simulator is built,and designed typical experimental conditions of adaptive cruise control system,and conducted a verification test regarding to aforementioned control strategy.The experimental results show that the designed algorithm of adaptive cruise control,the theoretical safety distance and the active rear wheel steering control can make the vehicle follow the preceding vehicle safely as well as improve the handling stability of the vehicle to a certain extent.