Predictive Control Methodof Automotive Semi-active Suspension Considering Pitch Dynamics

Magnetorheological semi-active suspension is a promising vehicle suspension and an indispensable part of the development of intelligent vehicles.Traditionally,the driver controls and adjusts the vehicle to ensure the safety and comfort of the vehicle.Intelligent vehicles can be driverless,which need to be controlled by the vehicle's own controller.Besides the safety of the vehicle,it also needs to consider how to ensure the comfort of the passengers.With the increasing mileage of Expressway in China,it is very important to ensure the comfort of passengers under the condition of expressway.In this paper,considering the complex non-linear characteristics of MR semi-active suspension,the predictive control method of automobile semi-active suspension is studied for a kind of driving conditions with pitching motion on expressway.Considering that the undulating pavement is generally symmetrical left and right,and the excitation and feedback to the left and right wheels of the vehicle are basically the same,a semi-vehicle model of MR semi-active suspension is established,which can represent the pitching and vertical motions of the vehicle.The non-linear characteristics of MR damper of semi-active suspension are described by hyperbolic tangent model,and the accuracy of the model is verified by simulation.Then,based on the established model,the mathematical description of model predictive control is given,and the problem of non-linear optimization calculation is analyzed.Due to the complexity of solving the nonlinear model predictive control problem,the non-linear items in the model are transformed into non-linear constraints by introducing virtual inputs,and the control problem of non-linear systems is transformed into a control problem of linear systems with non-linear constraints.A continuous/generalized minimum residuals method(C/G)is used to optimize the solution,and a disposable method is given.The predictive control method of MR damper for semi-active suspension is presented.The simulation is carried out in Simulink simulation environment of MATLAB and veDYNA simulation software with high accuracy.The results show that the MPC controller of semi-active suspension can effectively reduce the influence of pitch motion and vertical motion on vehicle comfort.Then the hardware-in-the-loop experiment is carried out with the control circuit board based on TMS570,which verifies the feasibility of the control method applied in the embedded system.Finally,in order to further reduce the calculation time and improve the real-time performance of the control algorithm,considering the higher order of the semi-active suspension and semi-vehicle model,the predictive control method is decomposed into the front and rear suspensions to form a distributed predictive controller,which reduces the number of iteration equations in principle and greatly reduces the operation time.The effectiveness of MPC controller for distributed semi-active suspension is verified by simulation.The simulation results show that the proposed distributed semi-active suspension controller can effectively suppress vehicle pitching and vertical motion.