An Output Feedback Approach To Active Suspension Of Intelligent Vehicle

With the development of Intelligent Vehicles, it is possible to acquire the characteristics of road and the state information of vehicle in real time, which can provide more effective information for active suspension control, and then the control performance of active suspension will be further improved. In order to enhance the performance of active suspension further, this paper discusses the control methods for active suspension based on the characteristics of road provided by Intelligent Vehicles.When travelling speed is constant and the road roughness is changeless, the vehicle-road coupling excitation possesses stationary random excitation characteristics. At present, the research of active suspension control is carried out under the precondition of this assumption extensively. Instead, in this paper, considering the vehicle-road coupling has non-stationary random excitation when the travelling speed and road roughness various. Considering the characteristics of non-stationary excitation change with time, firstly, this paper analyzes the frequency distribution characteristics of vehicle-road coupling excitation. On this basis, discussing the ideas and methods for active suspension controller according to the information of road roughness. And then, An output feedback control approach changing with road roughness is present. Finally, to verify the control effect, the simulation platform for active suspension system is built.In this paper, the second chapter puts forward a time-domain modeling method for single wheel road excitation. And then, we analyze the frequency distribution of the vehicle-road coupling excitation when the road level and travelling speed changes based on short-time fourier transform. The time-frequency characteristics of vehicle-road coupling excitation provide the basis for the active suspension controller design. The results of high precision veDYNA dynamic model and experiment show that the modeling method for vehicle-road coupling excitation is feasible and effectiveBased on the characteristics of vehicle-road coupling excitation, the third chapter of this article considers the vehicle ride comforts and handling stability performance, and then analyzes the design method of weighting functions according to different road level. In consideration of the available measurement information in practical application, a constrained output feedback H∞ control approach is present. The simulation results show that this control algorithm can inhibit disturbance of uneven road surface more effectively and improve the vehicle comfort.The fourth chapter in view of the sensitivity of human body to virbration in a limited frequency domain feature. Firstly, determining the upper limit and lower limit frequency based on the frequency distribution of road excitation, then considering the constraints of suspension deflection, dynamic tire load and active force, Finally, introducing generalized KYP lemma to convert the transfer function to linear matrix inequality(LMI), a finited frequency output feedback controller is present. And the simulation results verify the effectiveness of control algorithm.For the realization of the hardware in the loop simulation, this paper builds the simulation platform of active suspension system based on AMESim, LabVIEW and National Instruments equipment. The simulation model of vehicle and suspension system in AMESim is running in NI. Then, this article decribes the design procedures of data interaction module between AMESim and Lab VIEW, the sensor signal processing module, the CAN message sending and receiving module. The development of active suspension system provided simulation platform for the test of hardware in the loop.