| Due to the advantages of fast response,simple structure,low-power consumption and good safety performance,the semi-active suspension system based on magnetorheological(MR)damper has obtained widespread concern of researchers at home and abroad.Without considering the potential faults and treatment countermeasures,the traditional control strategy will lead to the degradation of system performance,and even invalidation in event of a malfunction.The study on the fault diagnosis and fault-tolerant control of MR semi-active suspension system will improve the reliability of the suspension system and has important theoretical significance and engineering application value.At present,there are few researches on the fault diagnosis and fault-tolerant control of vehicle MR suspension.Under the support of the national science and technology support plan project,this paper has carried on the systematic research of fault diagnosis and fault-tolerant control in the vehicle MR suspension system by both theoretical analysis and road experiment.The main contents of the paper are as follows:1)An unknown input observer residual was used to detect the actuator or sensor fault in the vehicle MR suspension system.On the basis of suspension system model and fault model,the observer coefficients were derived according to the designed observer structure,and then the simulations of faults(actuator and sensor output gain fault,stuck fault,constant deviation fault)were conducted.The results show that the designed observer can accurately detect the sensor and actuator faults with the independent of road excitation,and has strong robustness.2)The correlation coefficient method was used to isolate the fault of vehicle MR suspension control system.According to the correlation between the system residual and the actuator fault vector or the characteristic plane projection of sensor fault,the correlation coefficient of fault isolation was set up,thereby the fault was isolated in accordance with the correlation coefficient.In terms of the given fault isolation theory,the simulation study of actuator and sensor under various faults was carried out.The results show that the correlation coefficient method can be used to isolate the faults effectively.3)The internal condition monitoring system of the MR damper based on self-powered wireless communication technology was established.The internal temperature,pressure and piston's acceleration of the MR damper were employed to determine whether the damper is faulty.The experimental results show that the feasibility and effectiveness of the on-line monitoring system for the internal state of the MR damper,which provides an experimental verification platform for the observer-based fault diagnosis method.4)Aiming at the actuator gain fault of 1/4 vehicle suspension system,the skyhook fault-tolerant controller was designed for control compensation.The simulation results show that the proposed controller can attenuate the peak sprung mass acceleration passing through speed bump(high 0.1m)maximum by 61.21% with respect to without fault-tolerant when fault gain factor is 0.2.5)A fault-tolerant control method for the actuator failure of vehicle MR suspension was proposed.Through the decoupling transformation theory,the control law was re-optimized,and the renewed optimal control force of the system under partial damper failure was obtained and verified by simulation.The fault-tolerant control experiment system of vehicle MR suspension was established and the road experiment was carried out under random and pulse road excitation.The experimental results show that the proposed fault-tolerant control algorithm can effectively improve the performance of the MR suspension in the case of failure.In this study,the fault diagnosis and fault-tolerant control theory is applied to the vehicle MR suspension system.This approach can improve the control performance in the fault condition,enhance the operating stability and promote the development of MR suspension system technology. |
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