Multi-objective Optimization Control Of Vehicle Semi-active Suspension

During the running of the vehicle,uneven and undulating road surface will cause the body to produce pitching movement,thus affecting the ride comfort and driving safety of the vehicle.Therefore,in this paper,the semi-active suspension is taken as the research object.First,the reach of the damping force of the semi-active suspension is analyzed.Next,according to the two types of typical uneven road conditions—random road and fluctuating road,the corresponding semi-active suspension control strategy is designed to suppress the pitching motion of the vehicle and optimize the overall performance of the vehicle,which purpose improving the running smoothness and handling stability of the vehicle.Firstly,according to the knowledge of vehicle driving dynamics,this paper establishes an incentive model for random roads,pit-paved roads and long-wave roads,and analyzes the influence of different road-motivation on the pitching dynamics of vehicles.Then,the hyperbolic tangential inverse model and the damping force constrained model based on the magnetorheological semi-active suspension are established.After that,according to the pitch dynamics of the car and neglecting the slight influence of the roll motion on the pitching motion of the vehicle,a front-and-rear half-vehicle suspension model that can characterize the pitch and vertical motion of the vehicle was established,providing a model basis for the design of the post-controller.Next,according to the driving conditions of the vehicle on a random road,the system performance evaluation index based on the semi-active suspension of the vehicle is first introduced.O n this basis,the constraints optimal controller of the semi-active suspension are designed by analyzing the characteristics of the optimal control.In the process of designing the controller,the weighting coefficient of each sub-goal is determined by using the tomographic analysis method.And by comparing the different effects of the constrained optimal control under different weighting coefficients,it can be concluded that only by changing the weighting coefficient can it not be possible to optimize one performance index individually without sacrificing other performance.In view of this,the fuzzy optimal controller based on pitch angle optimization is designed.The simulation results show that the fuzzy optimal controller can further suppress the pitch angle of the vehicle on the premise of ensuring other performance.In the end,the special conditions of the vehicle running on the fluctuating road surface(including pit and long-wave pavement)is chosen.Firstly,the optimal controller is designed and the limitation of the optimal control for long-wave road surface is analyzed.Then the constraint model predictive control is designed to suppress the pitching motion of the vehicle,which purpose improving the running smoothness and steering stability of the vehicle.Considering that the vehicle will reac h the resonance state at high speeds,the model-based control methods are usually limited due to the inherent parameters of the suspension model.In view of this,the dual fuzzy controller with low requirement of the model is selected to suppress the vehic le pitch acceleration and vertical acceleration when passing through long-wave roads at high speeds.Finally,for the difference in the control effect exhibited by the dual-fuzzy controller and the model predictive controller when the vehicle passes through the long-wave road at an increasing speed,the speed switching controller is designed by analyzing the speed information of the critical points of each performance index,in order to optimize the vehicle performance further.The simulation results show that with the increase of the vehicle speed,the switching control can effectively improve the overall performance of the vehicle during driving.