Robust Sliding Mode Control Of Adaptive Cruise Control System For Electric Vehicles

The auto-adapted cruise control system monitors the running status of the vehicle in real time,and controls the throttle opening or brake pressure to ensure the ideal safety distance between the vehicle and the target following vehicle.As an important part of the advanced driver assistance system,the adaptive cruise system plays an important role in improving the safety,comfort and maneuverability of the vehicle during driving.This parper takes a four-wheeled hub motor-driven pure electric vehicle as the research object.The wheel hub motor can realize the unified integration of the power mechanism and the wheels,which can not only simplify the mechanical structure of the electric vehicle,but also enable the vehicle to achieve independent drive and independent steering and greatly enhance the flexibility of the vehicle in the control process.In this dissertation,when studying the adaptive cruise process of a four-wheeled hub-and-wheel motor pure electric vehicle,it mainly proceeds from the design of the discrete second-order sliding mode cruise tracking controller and the design of the auxiliary steering tracking controller.Among them,the cruise tracking controller in the design process,considering the strong nonlinear,time-varying,and strong disturbances of the vehicle model and the problem of mismatched models that occur with the increase in the service life of the vehicle,a data-driven subspace identification method is designed to estimate the state-space equations.The output is used as the input of a discrete second-order sliding mode cruise tracking controller to achieve a stable follow of the actual distance and the ideal safety distance.In order to improve the practicability of adaptive cruise system,this paper aims at the adaptive cruise following control of electric vehicles,and designs the steering assist control based on terminal sliding mode with the vehicle steering stability as the control target for the emergency turning conditions during vehicle driving.For the problem of insufficient torque in the steering process,a vehicle-based dynamic performance compensation controller based on a linear sliding mode is also designed to improve the dynamic performance of the vehicle during cornering.This paper adopts the torque distribution method based on the objective optimization function to distribute the vehicle demand torque to each hub motor to ensure the safety and stability of the vehicle during operation.Finally,through the AVL Crusie and Matlab/Simulink co-simulation,the control effect of the pure electric vehicle under the conditions of cruise control and vehicle following conditions is verified.The results show that the four-wheeled hub motor driven pure electric vehicle adaptive cruise control strategy can be achieved.Ensure that the car and the target vehicle have a good tracking effect during driving.The auxiliary steering controller proposed in this paper is verified by emergency turning conditions.The results show that this method can effectively ensure the stability of the vehicle in the steering process.