【作者】 余烽；

【导师】 徐中明；

【作者基本信息】 重庆大学 ， 车辆工程， 2011， 博士

【摘要】 全地形车是近几年兴起的集休闲、竞技、娱乐为一体的实用型车辆,且其军用潜力巨大。随着人们生活水平的提高,对全地形车的使用性能要求也越来越高。全地形车的整车振动水平是其重要的性能指标,直接影响乘员舒适、驾驶安全、车架等部件的强度等,是全地形车重要的产品品质因素之一。目前,国产全地形车整车振动水平与国外产品相比还有较大差距。本文针对全地形车振动及其控制的关键技术问题展开深入系统研究,具体包括以下几个方面的工作:①深入分析了ISO2631等相关振动标准,并结合全地形车自身振动特点,在国内首次系统的提出了基于时域法和频域法的全地形车整车振动评价方法及道路试验方法,以手把、坐垫及脚踏处加权加速度振级来评价驾驶员所受振动,以前后货架处加速度振级评价货架或平台处的振动。基于此方法,搭建了硬件测试系统,基于IMC FAMOS平台开发了软件分析系统,并针对多款全地形车进行了实车振动道路试验评价测试与分析。结果表明,时域法和频域法的结果相差很小,都可准确评价全地形车的振动。时域法思路清晰,计算速度更快,本文推荐使用时域法进行评价。②分析了多款全地形车车体结构动态特性,采用解析法和试验法分析了其车架结构动态特性,试验结果验证了所建立的车架有限元模型的正确性;在对车架挂发动机结构动态特性分析时,以有限元分析的基本原理为基础,找出了影响解析法结果的参数;结合简化模拟仿真分析结果,创造性的提出了将发动机简化为相同质心、质量及转动惯量的长方体,进而建立车架挂发动机有限元模型的新方法。试验法和解析法的结果对比表明,所提出的发动机简化方法简便可行,可在产品设计和改型阶段就能了解车架挂发动机结构的动态特性。以此方法改进了两款量产全地形车车体动特性,从车架及车架挂发动机结构动态特性的改进角度出发,分别对其车架的结构进行了改进,改进后的分析结果表明,所提出的改进措施均可行且易实施。③分析了发动机对全地形车振动的影响及其与车架的合理匹配。首先分析了车架挂发动机后发动机对车架的动态特性影响,结果表明,车架挂发动机后,后三阶自由频率振型发生了变化,但关心的前三阶频率均有所提高。进行了发动机在车架上的位置匹配分析,左、右、前、后平动对车架挂发动机动态特性影响分析结果表明,发动机对车架挂发动机的结构动特性有重要影响。④将形状优化方法应用到全地形车结构动态特性分析中。在国内首次采用了形状优化方法,以发动机安装位置和俯仰角度为变量对车架挂发动机的结构动态特性进行优化。优化结果表明,在保障其它几阶频率变化较小的情况下,优化后车架挂发动机的一阶模态频率有大幅的提高,有利于整车振动的控制。⑤建立了全地形车悬置系统刚体动力学模型,分析了其悬置系统固有频率及各个方向能量解耦情况。以各阶模态能量百分比占优方向上的能量解耦率最大为目标函数,四个悬置件的三向刚度为优化变量,采用模拟退火算法对悬置系统进行了能量解耦优化。结果表明,优化后Z向解耦率获得了大幅的提高,非常有利于全地形车整车的振动控制。⑥运用多体动力学软件ADAMS建立了包含柔性车架、前后悬架、转向系、轮胎和人体的全地形车刚柔耦合多体动力学模型。采用谐波叠加法生成了ADAMS/View格式的B级随机路面谱文件,并在ADAMS中施加了发动机激振力和激振力矩,从动力学仿真的角度分析了全地形车整车振动,为后续控制策略研究提供基础。⑦基于第5章建立的全地形车多体动力学模型,利用MATLAB/Simulink建立了包含天棚阻尼控制、模糊控制和模糊PID控制的悬架控制联合仿真系统模型。并在此基础上,分析了三种悬架控制策略效果。结果表明,模糊PID控制效果最佳,而且稳定性好,具有较强的鲁棒性。最后,对本文的研究工作进行了总结,并对下一步的研究进行了展望。更多还原

【Abstract】 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.更多还原