Adaptive Cruise Control System Of Hub Motor Electric Vehicle

Cars bring convenience to people’s lives, but also produced a series of social problems. With the increase in car ownership, traffic safety, energy consumption, environmental pollution, traffic congestion and other problems have become increasingly prominent. How to solve these problems become a hot topic in the automotive industry. Currently, electric cars, intelligence can effectively reduce energy consumption, reduce the burden on the driver’s driving and improve traffic safety. Therefore, the electric and intelligence become the future development trend of the car. As a kind of Advanced Driver Assistance Systems(ADAS), Adaptive Cruise Control(ACC) System can effectively reduce the burden on drivers, improve road safety and reduce traffic congestion to some extent. Based on the National 863 Program "The Electric Vehicle Chassis Dynamics Control System Development", this paper presents adaptive cruise control system of hub motor electric vehicle.First, this paper selected four-wheel hub motor electric vehicle as the target type. The hub motor electric vehicle eliminates the engine, transmission and other mechanical devices to reduce vehicle weight and improve transmission efficiency. Based on the target vehicle, this paper developed a vehicle modeling program, and select the permanent magnet synchronous motor to drive the car, and then on the basis of CarSim vehicle model, modify powertrain, built in-wheel motor electric-vehicle model and simulation verify the validity of the model.Then, according to the working characteristics of an adaptive cruise control system, developed a system control mode switching strategy, including the driver’s control policy priority, the system working mode switching strategy and drive/brake switch strategy to ensure that the driver can keep control of the vehicle and system uptime; Access to a large number of references, a safe distance algorithm which consider the acceleration of the target car is proposed, and stability is analyzed. This paper designed the upper controller based on the linear quadratic optimal control theory, and this controller meet the requirement of follow stability and it has good real-time; Analysis of vehicle longitudinal dynamics model, the lower controller is designed according to the principle of self-tuning fuzzy PID using Matlab fuzzy toolbox.At last, the ACC controller is designed according to the proposed algorithm in the Matlab/Simulink environment, and electric vehicle models built jointly ACC system simulation platform. Though CarSim and Simulink combine, this paper simulate the cruise control, vehicle following, cut in, cut out, stop and go five typical working condition. The simulation results show that the adaptive cruise control algorithm developed in this paper effects good, able to adapt to changes in the traffic environment, and meet the design requirements of the adaptive cruise control system in offline environment.