Research On Model Predictive Control And Implementation For Active Suspensions Excited By A Long Sinusoidal Road

Vehicles often run very fast on the expressway,while there may be up and downs along the expressway road surface.To deal with this condition,this paper presents a model predictive control method,and its implementation in vehicle control units.This paper first focuses on the condition of high-speed vehicles on a long sinusoidal road,and establishes a half-vehicle model.With the consideration of the constraints of forces generated by active suspension actuators,in order to optimize the accelerations of vehicle body vertical displacement and pitch angle,a model predictive controller is designed.After that,Simulink and high-precision vehicle dynamical model ve DYNA are carried out to run the simulation,and the results prove that the model predictive controller with varying weights can lower the accelerations of vehicle body vertical displacement and pitch angle,to improve the comfort.In order to reduce computational complexity of the designed MPC controller,a distributed implementation method of MPC controllers.The high-order half-vehicle model system is divided into three low-order subsystems,and then the distributed optimization process is derived.Still choosing the accelerations of vehicle body vertical displacement and pitch angle as the optimization objective,this paper gives out a distributed MPC subproblem for each suspension subsystem.Simulation results show that the distributed MPC method can inhibit the vehicle body vertical and pitch movements,and can shorten the running time of the original MPC controller.Considering that the computing power of vehicle control units are not very good,this paper uses a Continuation/GMRES(C/G)method to solve the MPC problems in control units.Firstly,the principle of C/G method is analyzed,and the code implementation and encapsulation are finished in MATLAB,C,and s-function environments,which forms a reusable solving tool for MPC problem.Then to deal with the limitation when calculating the initial value,in connect with the specific problem of active suspension control,this paper suggests C/G method start whenever the vehicle starts,and gives out the initial values of two distributed MPC subproblems.At last,this paper use C/G method to run the active suspension distributed MPC controllers in C environment,and the result proves the validity of C/G method.This paper also establishes the FlexRay communication network among TMS570 control units,to transmit parameters from a distributed subsystem to another.Reusable drivers are prepared,and the FlexRay communication protocol is configured to satisfy the requirements of parameter transmission among distributed subsystems.A set of FlexRay time parameters are also configured on the basis of the protocol.At last,three TMS570 circuit boards are connected together,and the distributed MPC controllers and FlexRay communication are combined.The results show that the real-time implementation of the distributed MPC controllers in TMS570 vehicle control units is finished.