| Magneto-rheological dampers（MRD）require electrical power response,electromagnetic response,MR fluid response,and damper structure response during operation,which results in a time delay in the control of semi-active suspension.Aiming at the time-delay problem of the MR semi-active suspension system,based on the theoretical analysis,numerical simulation and experimental research methods,MRD mechanical model was established and Taylor series based improved H2/H∞control for time delay compensation of MR semi-active suspension is studied.The specific research work is as follows:Firstly,the mechanical properties of the MRD were tested,and the hyperbolic tangent model of the MRD was established based on the experimental results.Through the analysis of the model,it is known that the output force of the MRD is composed of the control force affected by the current and the output force that is not affected by the current,and the output force affected by the non-current includes a nonlinear portion.Secondly,in order to construct a MR semi-active suspension model with time-delay,combined with that the H2/H∞controller can handle the control force disturbance,the output forces that are not influenced by the current are divided into base-valued viscous damping force and non-base-valued viscous damping force.It is proposed that the non-basis viscous damping force is used as a disturbance force to lay the foundation for designing a Taylor series-based time-delay compensation controller.Thirdly,Taylor series based improved H2/H∞delay compensation control is proposed to solve the problem of time-delays in the MR semi-active suspension system.For the time delay problem,the first-order Taylor series is used to predict the future control force of the time-delay control force.The first-order Taylor series-delay equation and the suspension system state equation are combined to form the augmented state equation and the Taylor series-H2 controller is designed to control the predictive control force to optimize the evaluation index of the overall performance of the suspension.For the problem of predictive control force amplification,the Taylor series-H2/H∞controller is performed using the H∞norm to constrain predictive control force.Taylor series-H2/H∞controller is analyzed conservatively.It is proposed to use H2norm to constrain predictive control force and Taylor series-H2/H2 controller is designed.Based on Taylor series-H2/H2 controller,in order to obtain an accurate ideal control force,an H2 controller is used instead of the first-order Taylor series-delay equation to determine the input ideal control force.Finally,MATLAB/Simulink is used to construct the passive suspension,ideal MR Semi-active suspension model controlled by H2 controller and time-delay MR semi-active suspension model with time-delay compensation control.The results show that when the time delay of MR semi-active suspension is 30ms,compared with the passive suspension,the J value of MR series semi-active suspension controlled by Taylor series-H2/H∞is improved by 24.40%;The J value of the MR semi-active suspension system controlled by Taylor series-H2/H2 is improved by 28.40%and the J value of the MR semi-active suspension controlled by Taylor series-H2/H2/H2 is improved by 31.02%.The Taylor series-improved H2/H∞time-delay compensation control strategy can effectively improve the overall performance index of the vehicle.Taylor series based improved H2/H∞delay compensation control of MR semi-active suspension proposed in this paper can provide certain theoretical and experimental basis for the application of semi-active suspension. |
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