Research On Robust And Fault-Tolerant Control Methods Of Active Suspension

As one of the important systems of automobile chassis,suspension directly affects the ride and operation stability of the whole vehicle.The development of intelligent electric vehicles,as well as the complex and changeable driving conditions of vehicles,make the performance requirements of suspension system more and more high,and the traditional suspension is difficult to meet the growing demand.Therefore,active suspension has always been one of the hot spots in the research of automotive intelligent chassis system.The components of active suspension will perturb or even fail with the increase of time,which will seriously affect the normal work and performance of the suspension.Robust control has the advantage of being insensitive to parameter disturbance and ensuring the stability of the system.Fault-tolerant control can make the performance indexes of the control system meet the requirements under the condition of intact and fault-free.Therefore,robust and fault-tolerant control of active suspension system is an effective way to improve the dynamic characteristics of suspension.In this paper,the fault detection and diagnosis of active suspension actuators are carried out,and the fault tolerant control and robust fault tolerant control strategies of active suspension are studied.The main research contents of this paper are as follows:（1）The performance evaluation method of suspension is introduced and fault tolerance is put forward into the performance evaluation method.Based on the two-degree-of-freedom 1/4 vehicle model and random road model,the active suspension adaptive LQG controller based on analytic hierarchy process（AHP）was designed and simulated without considering the faults of each component.The analysis results shows that the active suspension adaptive LQG based on analytic hierarchy process has better control effect and can improve the ride comfort of the vehicle.（2）The active suspension actuator fault model is established,and the vehicle state estimator is designed based on the kalman filter principle.The vehicle state is estimated in real time,and the residual information before and after suspension fault is extracted.Combined with the state estimator’s estimation of vehicle state and fault diagnosis results,an active suspension actuator fault compensation fault-tolerant control method based on residual theory is proposed and simulated.The analysis results show that the designed state estimator has a good effect on the fault detection of the actuator,the fault-tolerant control method proposed based on control force compensation can well compensate the control force lost of the actuator,so that the fault suspension can restore its normal state quickly,and improve the reliability of the active suspension.（3）Taking two-degrees-of-freedom 1/4 vehicle model as the research object,the normal H₂/H_∞state feedback controller is designed based on the H₂/H_∞state feedback control rate.In order to solve the uncertainties such as parameter perturbation and actuator fault,an active suspension model with parameter perturbation based on linear fractional transformation is constructed.A robust fault-tolerant controller based on H₂/H_∞for active suspension is derived and designed by using linear matrix inequality（LMI）method,and the simulation analysis is carried out.The results show that compared with the normal H₂/H_∞state feedback control,the designed robust fault-tolerant controller enables the suspension system to be robust to faults,which can improve the ride comfort of the vehicle and ensure the safety of the active suspension system.