| With the elimination and scrapping of the old commercial vehicles(China Ⅲ and China Ⅳ)and the start of the 14 th Five-Year Plan,the commercial vehicle market has continued to expand in the past two years.With the economic growth,customers are more concerned about the riding comfort.In order to win the recognition of customers,suppliers have increased investment in research and development,hoping to seize the market through technological upgrades.The suspension system is a vibration damping device connecting the frame and the cab.Once the damping and stiffness of the traditional suspension are selected,they cannot be changed during driving and cannot adapt to changing road conditions.In this thesis,for a certain 8x4 dump truck,based on the MRD(Magnetorheological Damper),it is planned to research and develop a semi-active suspension electronic control system with continuously adjustable damping.Firstly,the working principle of the MRD which is the executive device of the electronic control system,is introduced in the thesis,and a certain MRD is selected for research.Its performance is tested by experiments,and two parametric models,BoucWen and Dahl,are established in Simulink based on the experimental data.Their fitting effects are compared and analyzed.Open-loop control and closed-loop control are used as the control methods of MRD,and a compensation closed-loop control is proposed.The advantages and disadvantages of the three control methods are compared by simulation.Secondly,the semi-active control strategy is researched in this thesis.Through the research on the principles of skyhook damping control,PID semi-active control and optimal control,the characteristics of the three are compared.Based on PID control and optimal control theory,Smith-PID controller,fuzzy PID controller and LQG controller are designed.In this thesis,the vertical,pitch and roll directions of the cab are semi-actively controlled,and the control effects of the three controllers are quantified through modeling and simulation.The control effects of the three controllers are compared and analyzed.Thirdly,based on the requirements of the national standard and the actual situation,the ride comfort data of the 8x4 commercial vehicle is measured to provide comparative parameters after the semi-active suspension was mounted.At the same time,the inertial parameters of the cab are measured by the test modal method,and the important parameters required by the control algorithm such as the cab’s center of mass and moment of inertia are obtained.Finally,the thesis describes the design process of software and hardware in detail.The software design adopts the development method of MBD(Model-Based Design).NXP’s S32K1 xx series main processor and its model development tools are used to build the driver environment and application layer software model on Simulink.The feasibility of using the tool chain for software development is verified through unit testing.Regarding the hardware part of the controller,the selection of sensors and driver chips has been completed around the S32K144 processor,and the design of the minimum system circuit,power supply circuit,communication circuit,and drive circuit has been completed. |
