Study On Vibration And Control Of All Terrain Vehicle

All-terrain vehicle (ATV) is a practical mechanical equipment developed in recent years. The vehicle has integrated the functions of entertainment and sport, and has enormous military potential. With the development of the living standard of the people, the requirement for ATV service performance is getting higher and higher. The vibration levels is an important performance indicators and quality factor of ATV which also has a direct bearing on its occupant comfort, driving dafety, the strength of frame and other components and so on. At present, the vibration of domestic ATV and foreign products has bigger difference. This paper carries out research on the key technique of evaluating and controlling the vibration of the entire vehicle. The research work involves several aspects as follows:①Considering the characteristic of ATV vibration, the methods about evaluating the ATV vibration in frequency domain and time domain and road test are proposed through deep analysis of ISO2631. The weighted vibration level at handlebar, cushion and treading is used to evaluate the vibration of the driver, while the vibration level at front and rear luggage carrier is used to evaluate the vibration of the platform. The system’s hardware is set up based on this method and the software is developed based on IMC FAMOS. Vibration comfort of two vehicles is tested and analyzed. Analysis results demonstrate that both time-domain method and frequency-domain method are exact to evaluate the vibration of the whole vehicle. The time-domain method is characterized by speedy in computation and simple operation, and is suggested to use.②The dynamic characteristics of ATV frame are analyzed by analytical and experimental methods. The results prove that the finite element model is reliable. The dynamic characteristics of ATV frame with a mounted engine are analyzed by FEM to find out the parameters that affect the result of analytical method. Incorporating analysis of simplified simulation, a simple and common finite-element modeling method is proposed which simplified the engine as a meshed cuboid structure with same centroid, weight and rotary inertia to the engine. The feasibility and validity of the method is verified by comparing the simulation results with experimental results. This simple and common modeling method is useful to know the structural dynamic characteristic of ATV frame elastically connected with engine in the phase of product design and retrofit. Take two ATV vehicles as an example, their frame structure are changed to improve the dynamic characteristics of ATV frame. The analysis showed that improvement actions are available and easy-to-implement.③This paper analyzes the influence of engine on the dynamic characteristics of ATV frame. The results show that when the engine is mounted on the frame, the last three modal shapes changes and the first three modal frequencies improves. The influence of the engine position on the ATV frame has been analyzed, which shows that the engine position have a major influence on the dynamic characteristics of ATV frame with engine.④Shape optimization method is used to improve the dynamic characteristics of ATV frame, taking the position and pitch angle of the engine on the frame as the variables. By means of adjusting the position and pitch angle of the engine according to the optimization result, the first modal frequency of ATV bodywork was increased vastly, while other frequencies change little. It helps to keep the vehicle under control.⑤A vehicle is simplified into a multi-rigid body dynamic model to analyze the natural frequency of mounting system and its energy decoupling. Then, the simulated annealing algorithm is used to decouple the energy of the mounting system. For optimization, the stiffness of four mountings is taken as the variables, and the decoupling of power is taken as the objective. The results show that the energy decoupling rate of direction Z get a large increase which is very conducive to all-terrain-vehicle control.⑥By ADAMS, the multi-bodies dynamics software, a virtual prototype of rigid-flexible coupling model for ATV is built, including flexible frame, front and rear suspension, steering system, tires and human body. The simulated B-class road profile is generated by wave superposition method in Adams/car format. The whole vehicle vibration under the engine excitation force and torque is investigated, which provided the basis for further research.⑦In order to control the vibration, united simulation model of suspension control system, including sky-hook control, fuzzy control and fuzzy PID control, is built by using MATLAB/Simulink. This control system is based on the multi-rigid body dynamic model that was built in Chapter 5, and is used to analyze control effect of the three strategies. The results show that fuzzy PID control has the best effect, and is steady and robust.The final part is the conclusion, which introduces the main conclusions and makes some suggestions for future research on the topic under investigation.