| In recent years,with the improvement of material and living standards,consumers have put forward higher requirements for vehicle dynamic performance.Traditional passive suspension is difficult to satisfy the requirements of vehicle dynamic performance under different road conditions because of its non-adjustable control parameters.Although active suspension can effectively improve the dynamic performance of the vehicle,its popularity is limited by the complex system structure and the additional energy consumption.Semi-active suspension can coordinate the contradiction between dynamic performance and energy consumption,which has become a research hotspot in the automotive field.However,the current research on semi-active suspension control ignores the influence of road excitation on the control effect,which makes the designed control parameters difficult to adapt to the dynamic performance requirements when the road conditions change.Therefore,this paper proposes a switching control strategy by combining the online road estimation technology with semi-active suspension control,which can effectively improve the dynamic performance of the vehicle under different road conditions.The main research contents are as follows:Firstly,a two-degree-of-freedom quarter car model equipped with MR damper is established,and the characteristics of MR damper are tested.On this basis,a polynomial model of MR damper is established.The models of continuous random road and discrete bump road are established,which are used as the road profile excitation.Then,according to the transmission characteristics of suspension system,an online road estimation method based on vehicle dynamic response is designed.The road profile estimator is designed based on the adaptive neural fuzzy network,and according to estimation results,an AR power spectral density estimation-based road level classification method is developed.Furthermore,the simulation of road profile estimation and road level classification is carried out,which verifies the effectiveness and feasibility of the online road estimation method.Thirdly,based on the online road estimation method and the modified skyhook control strategy,a switching controller with multiple sub controllers is designed.According to the road level and driving speed,the control objectives under different driving condition are divided,and the optimal control parameters under each control objectives are determined using cuckoo search algorithm.On this basis,the simulation comparison analysis under the random road sequence is carried out,and the simulation results verify the rationality of control objective division and control parameter optimization.Finally,a 1/4 semi-active suspension test bench is built,and the online road estimation and dynamic control test are carried out.The test results are consistent with simulation results,which verify the correctness of the simulation results and the feasibility of the online road estimation method and the switching control strategy.The theoretical analysis and test results show that the switching control strategy with the road level as the switching condition can improve the vehicle dynamic performance under all road condition.Specifically,compared with the passive suspension,under the B-class road with the main control objective of handling stability,the suspension working space and dynamic tire load of magnetorheological semi-active suspension are optimized by 9.2% and-4.2% respectively;under the C-class road,which takes the comprehensive performance of the ride comfort and handling stability as the main control objective,the body acceleration,the suspension working space and the dynamic tire load are optimized by 16.0%,7.6% and-6.8% respectively;under the D-class road with the main control objective of ride comfort,the body acceleration and the suspension working space are optimized by 20.0% and 5.1% respectively. |
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