Research On State Observation Based On SSUKF Observer And Extension Control For Semi-active Suspension

With the development of automotive suspension electronic control technology,the demand of the suspension system performance is constantly increasing.The adjustment of the semi-active suspension can improve the ride comfort performance of the suspension.Because of the simple algorithm and high reliability,the research on the semi-active suspension of the sky-hook control has attracted extensive attention at home and abroad.In order to improve the ride comfort and driving safety performance of the vehicle under the sky-hook control,spherical simplex unscented Kalman filtering algorithm observer is designed by MATLAB.Based on suspension ride comfort and driving safety indexes,the sky-hook and ground-hook hybrid extension control system is established,which can intelligently switch the control method,suppressing the vibration of the sprung mass and the unsprung mass.The software and hardware design and bench test are carried out to verify the performance of the control system.Based on the vehicle suspension dynamics,the models of two-degree-of-freedom(2-dof)and seven-degree-of-freedom(7-dof)controlled suspensions were built.The analysis of sky-hook control,ground-hook control and SGHC under frequency domain were obtained.Based on vehicle dynamics and random vibration theory,the time-domain road excitation model was derived.The vehicle dynamics simulation software CarSim and the two controlled suspension models verified the feasibility of the two controlled suspensions,which provided the model for the study of ride comfort and driving safety.Then,in order to measure the driving state of the suspension system,a kind of suspension observer system was designed.The system was based on Kalman filtering theory,adding symmetrical sampling to obtain the standard unscented Kalman filtering suspension observer system.By means of measuring part of the ride comfort index and road surface information,the driving state of the suspension system was predicted.In order to improve the real-time performance of the suspension observer,the symmetry sampling was replaced by the spherical simplex sampling,and the SSUKF suspension observer system was designed.Based on the 2-dof sky-hook control model,the SSUKF observer and the SUKF observer were compiled in MATLAB software.The comparison of SSUKF,SUKF,and other filtering algorithms verified the estimation accuracy and calculation speed of SSUKF.Subsequently,based on the extension theory,the SGHEC suspension system was designed.The control system was composed of upper and lower controllers.The upper layer was an extension controller,and the weight of the lower layer controller was determined by the correlation function.The lower controller was a hybrid controller.According to the weight of the upper controller,the switching of sky-hook control,ground-hook control,and SGHC were realized.The SGHEC suspension model was built to verify the feasibility of SGHEC system.Through the joint simulation of MATLAB/Simulink and ve-DYNA software,the vehicle ride comfort and driving safety of the passive suspension system,the sky-hook control system,and the SGHEC system in the time and frequency domains were compared and analyzed.The simulation showed that the SGHEC suspension can ensure the performance of ride comfort and driving safety.Finally,SGHEC bench with SSUKF observer was conducted.Compared with the passive suspension system,the results of the test showed that the body acceleration decreased by 34% and the tire dynamic load decreased by 6%.The ride comfort and driving safety feasibility of the SGHEC with SSUKF observer could be verified.