Research On The Active Fault-Tolerant Control And Prototyping Of Magnetorheological Semi-Active Suspension System

The semi-active suspension system based on magnetorheological shock absorber has been widely concerned by domestic and foreign scholars because of its simple structure,continuous adjustable resistance,fast response and low energy consumption.As semi-active control system,any fault of the system will affect the control of the magnetorheological suspension system,which makes the fault-tolerant control necessary for magnetorheological semi-active suspension system.The work of this paper mainly starts from the research on active fault-tolerant control method and prototyping of magnetorheological semi-active suspension system.The fault-tolerant control of vehicle magnetorheological semi-active suspension system mainly includes fault detection and fault signal output reconstruction.As a nonlinear system,the state estimation of the magnetorheological semi-active suspension system is carried out by the unscented Kalman filter,which avoids the modeling error introduced by the approximation algorithms in linear modeling.Based on the state space model of the quarter car,the semi-active suspension system sensor fault diagnosis system based on a set of unscented Kalman filter is designed.By comparing the residual sequence of unscented Kalman filter with the preset threshold,the fault could be detected and the fault signal could be reconstructed according to the results of state estimation.Thus the process of fault detection,isolation and output construction of single sensor fault is realized.For different requirements of ride comfort and driving safety under various driving conditions,this paper adopts the Skyhook-Groundhook hybrid damping control which adapts the control requirements of different performance of magnetorheological semi-active suspension system by adjusting the weighting coefficient between Skyhook and Groundhook control.The simulation results show that increasing the weighting coefficient can effectively improve ride comfort but worsens the driving safety to some extent,on the contrary,reducing the weighting coefficient improves the driving safety and reduces the riding comfort.At last,the quarter car semi-active suspension system and the whole car semi-active suspension system with and without fault-tolerant control are compared with Matlab / Simulink and Car Sim combined simulation.The results show that the fault-tolerant control under different sensor fautls can effectively improve the reliability and stability of the control system.For the prototype development of the magnetorheological semi-active suspension system,a group of four magnetorheological shock absorber prototypes with internal bypass are designed and manufactured based on the prototype a small new energy vehicle,and the damping force characteristics of the designed magnetorheological shock absorber prototypes are tested on the servo-hydraulic excitation platform.The test results show that the damping force characteristics of the designed magnetorheological shock absorber prototypes meet the requirements of the vehicle suspension performance.According to the control requirements of the vehicle semi-active suspension,a controller and a controllable current driver for the magnetorheological suspension system are designed.Finally,the prototype of the vehicle magnetorheological semi-active suspension system is installed according to the structural installation requirements of the suspension system.