Research On The Stability Control System Of Vehicle Active Suspension

The environment of vehicle traffic is complex and changeable, due to the changes of road conditions(road roughness grade), vehicle speed and operating mode(straight, acceleration, braking, steering) will changes the vehicle state.During the heavy acceleration vehicle will produce “accelerated back”,high-speed emergency braking will produce "brake nod" phenomenon and when the vehicle turning drive will produce the phenomenon such as “to roll” which will seriously affect the riding comfort and operation stability of the vehicle.Passive suspension due to its immutable structure stiffness and damping characteristics makes it difficult to ensure ride comfort and handling stability while achieving the best results. To solve this problem came into being electronically controlled suspension, electronically controlled suspension according to driving conditions of the vehicle to ensure the vehicle’s performance to an optimum level.The main content of this paper by comparing the features of the Fuzzy-PID control strategy and RBF-PID control strategy and select the higher performance control strategy establishing the entire vehicle vertical, roll and pitch sub-controller, then using fuzzy reasoning the operation condition of judgment about cars, eventually to build a whole vehicle controller based on functional allocation. Firstly introduces the characteristics and classification of electronic control suspension, establishes suspension pavement input model, the establishment of road input model vehicle suspension and 1/4 of two degree of freedom passive suspension and active suspension simulation model whilebuilding seven- freedom suspension model which can fully reflect the attitude of the whole car. Secondly according to the principle of PID and fuzzy control theory is based on a quarter vehicle suspension model of two degrees of freedom active controller is set up respectively and simulation comparison;Then building the Fuzzy-PID controller based on the movement principle and parameters of suspension and using the simulation to verify the Fuzzy-PID controller has a better performance on active suspension control. Furthermore by using of RBF neural network feature combines the advantages of PID control based on vehicle model 1/4 designing the RBF-PID controller, the simulation contrast RBF-PID comprehensive performance is better than Fuzzy-PID controller. Finally, select the excellent performance of the RBF-PID controller as vehicle body, roll, pitch of sub controllers; while taking advantage of the fuzzy inference car’s driving cycle judgment, by changing the weights of the three sub-controller to the car under different conditions for vertical, roll and pitch of the inhibition degree, improve the comprehensive performance of suspension when the vehicle under different conditions.Under certain road input, through the establishment of the model in Simulink simulation results show that: the Fuzzy-PID controller has a better performance of active suspension control than PID, fuzzy controller, and significantly lower suspension vertical acceleration at the same time reduces the wheel suspension travel and dynamic deflection; RBF-PID controller is more significant to inhibition of vertical acceleration than Fuzzy-PID controller. The function of the fuzzy reasoning applied to build distribution controller can be changed according to the running condition of the vehicle to the vertical, roll and pitch control degree, improve the overall driving performance of the car.