Research On Design And Experiment Of Multi-level Adjustable Damping Semi-active Suspension Control Based On Multi-operating Conditions For A Sedan

This paper used the magnetorheological damper to develop multi-level adjustable damping semi-active suspension based on multi-operating conditions,established simulation platform,weighed and set multi-operating condition control target,optimized the control parameters to improve the vehicle performance under multi-operating conditions.The paper mainly elaborated the content as follows:(1)By searching relevant literatures,the adjustable damping semi-active suspension damper and the control algorithm,the practical situation and the related control strategy of the multi-operating condition adjustable damping semi-active suspension were reviewed.(2)Derived the four-wheel road model formula based on the road grading theory,the left and right wheel characteristics and the front and rear wheelbase characteristics,derived passive suspension,semi-active suspension quarter vehicle model and seven degrees of freedom vehicle model,created the model based on MATLAB software.(3)Applied the LQG control according to the semi-active quarter vehicle model,the seven-degree-of-freedom model formula and the road model formula and divided the different performance control objectives.The uniform straight-line driving condition mainly considers the trade-off between ride comfort and handling stability.Transformed the semi-active suspension LQG control problem into a multi-objective control problem with constraints.Transformed the multi-objective problem into a single-objective problem by using the weight coefficient transformation method and optimized the control parameters by applying the genetic algorithm.The simulation results show that the LQG control can improve the comfort of the ride with the small handling stability cost.(4)Built the vehicle system dynamics software Carsim and MATLAB cosimulation platform and carried out the characteristic test of magnetorheological fluid and the damping characteristic test of magnetorheological dampers.Based on the experimental data,BP neural network theory was used to establish the inverse model.Combined with the vehicle system dynamics cosimulation platform to set the standard test conditions and used genetic algorithm to optimize the control parameters.The special test conditions mainly considered the body posture control.(5)Built the semi-physical hardware in the loop platform to verify the effectiveness of the control algorithm,the platform is divided into three parts: the controllers,the actuators and other necessary devices.The controller design includes the hardware circuit design based on the Freescale microcontroller and the software design that combines the Codewarrior PE function with MATLAB Stateflow to generate code automatically.Based on the Carsim RT software and the d SPACE Auto Box real-time simulation environment,the passive suspension and the sub-optimal control hardware-in-the-loop verification experiment combined with the related software model were carried out for the partially uniform linear driving condition and the special working condition.