| In order to solve the problem of severe vibration of wheeled transport vehicles in hilly mountains and improve the driving comfort of drivers and the quality of transport materials,this thesis studies the semi-active suspension of hilly wheeled transporters.At present,the research status at home and abroad is mainly concentrated on In the study of semi-active suspension systems for cars,there are few studies on semi-active suspension systems for agricultural vehicles.In order to solve the problem of difficult transportation in hilly and mountainous areas in South China,the team has developed a hilly mountain wheeled transporter.The front axle of the previously developed mountain orchard transporter adopts a rigid connection arrangement without a suspension system,and the transporter is transported on the mountain road.The vibration generated by the vehicle has a great influence on the driver.Working under such conditions for a long time will increase the driver’s driving fatigue and affect the safety of driving.At the same time,the vibration generated also has a direct impact on the quality of the transported fruit.Indirectly causing economic losses.Therefore,it is very meaningful to develop a suspension system suitable for mountain orchard transport aircraft.In this paper,considering the simple structure,mature technology and low cost of the CDC damper,a semi-active suspension system using CDC damper is designed for hilly orchard electric wheeled transporter based on the research and development of laboratory.Fuzzy PID control method is used to control the semi-active suspension system,and an effective semi-active suspension system is designed through loading test.According to the suspension system dynamics model,the Simulink model of the fuzzy-PID controller is established by matlab,and its parameters are analyzed and adjusted.The ideal simulation results are obtained.The analysis shows that the performance of semi-active suspension system is improved by 10%-20% than that of passive suspension system.Design the hardware part of the semi-active suspension system and carry out the loading test.The mechanical structure part of the design system includes the elastic element,the damper modification,the guiding mechanism and the connection parts of each part.The system layout is arranged considering the front axle arrangement space,and the damper is adopted.The system is arranged in an oblique arrangement with an angle of 30° with the horizontal plane,the elastic elements are arranged vertically,and the guiding mechanism is installed at the middle position of the front axle to limit the movement of the front axle and to constrain the vertical movement.According to the fuzzy PID controller designed in the previous section,the control circuit system is designed.The acceleration sensor is arranged in the middle of the vehicle body.The control chip uses the stm32 chip.The signal amplification circuit uses the pulse control module.The power supply is rated at 12 V and the rated current is 5A.And the system is powered.Based on ANSYS software,the finite element statics simulation analysis and fatigue life analysis of the mechanical structure of the suspension system are carried out.Under the premise of meeting the mechanical properties and reliability of the structural requirements,the main structure of the front axle assembly is optimized based on multi-objective optimization.Quantitative design,optimized design results are 43.26% lighter than the original weight,and the lightweight effect is significant.Finally,the semi-active suspension loading test is carried out,and the vibration test system is constructed by using the vibrometer and the vibration sensor to test the vibration signal of the z-axis of the seat position of the vehicle during driving,and comparing the test results with the original state after loading.It can be obtained that the vibration attenuation of the transporter equipped with semi-active suspension exceeds 50% under the conditions of speed and load,respectively,which meets the design requirements of the semi-active suspension system.The vibration frequency of the vehicle body equipped with the semiactive suspension system is more than 8 Hz,indicating that the driving comfort of the vehicle is better. |
