| At present,the world’s increasing demand for energy has promoted the rapid development of the commercial vehicle as the carrier of the transportation industry.China attaches great importance to the technological innovation of commercial vehicles and expects to promote the development of commercial vehicles to meet the more diversified needs in the future.The commercial vehicle is heavy,the driving environment is bad,the uneven road surface caused by the vehicle body vibration,will cause the driver’s discomfort,in the long run will seriously damage the driver’s physical and mental health.Due to the high carrying capacity demand of transporters and maintenance cost control,leaf spring suspension is widely used.Suspension is the core subsystem of the vehicle.Its role is to provide support for the sprung mass,transfer the force and moment between the wheel and the frame,mitigate the impact of uneven road excitation on the sprung mass,and mitigate the vibration caused by it,so as to ensure the smooth running of the vehicle.The key design requirements of the vehicle suspension system are to ensure the comfort of the driver and the passenger and the grounding of the tire.While satisfying the above two functions,the dynamic travel of the suspension should be guaranteed within the allowable limit.The stiffness damping of traditional leaf spring suspension varies non-linearly with the state of suspension and cannot adapt to various road conditions.Therefore,it is very necessary to study how to improve the vehicle ride comfort and safety with leaf spring suspension system.The main research work of this paper is as follows:（1）For nonlinear systems,an algorithm of hypersphere distribution untraced Kalman filter（SSUKF-UI）suitable for unknown input is proposed.Based on the traditional Unscented Kalman filter（UKF）algorithm,the algorithm combines the hypersphere sampling transform（SSUT）.At the same time,the least square method is used to synchronously identify the unknown inputs,which improves the accuracy of the observer state estimation under the condition of unknown inputs.（2）A robust H?fuzzy sampling controller design method for nonlinear systems with state feedback and output feedback is proposed.In view of the nonlinear system,in order to 1)system asymptotically stable under without outside interference,and 2)under control output to minimize interference,3)constraint output fluctuations within a certain scope as control target,in the state and part of the state of information as a controller input respectively designed state feedback and output feedback robust fuzzy sampling controller.The convex combinatorial inequalities satisfying the control objectives were obtained by using Lyapunov functional method,and the robust control gains of state feedback and output feedback were derived by combining the LMI technique.（3）An observer（SSUKF-UI）-control(output feedback robust H?fuzzy sampling control)closed loop system for nonlinear leaf spring suspension was proposed.Based on sensor to measure acceleration of sprung mass and unsprung mass information,combined with SSUKF-UI of leaf spring suspension state and pavement unknown displacement excitation state estimation,with reference to the state information of the observed leaf spring suspension system output feedback robust H?fuzzy sampling controller input,calculate the control,the suspension system of the sprung mass vibration acceleration,The suspension dynamic travel and tire dynamic load are actively controlled,which effectively improves the ride comfort and safety of the suspension system.To sum up,this paper takes the leaf spring suspension as the research object.Aiming at the nonlinear characteristics of the leaf spring suspension system and the complex and variable road excitation problems,the research on the synchronization observation algorithm of the unknown input and system state of the nonlinear system is carried out.Multi-objective requirement for the leaf spring suspension system,consider comfort（minimize sprung acceleration）,security（suspension travel and tyre dynamic load fluctuations within a certain range）,conducted of the nonlinear system state feedback and output feedback robust H?fuzzy sampling controller strategy research,research to improve the comfort and security of the suspension system.This paper provides a new research idea for nonlinear suspension system state and pavement synchronization estimation method and nonlinear suspension system control algorithm under the condition of complex and changeable road surface,which has good practical value. |
