交叉变轮距车辆转向机构运动学研究

发布时间：2018-01-19 22:33

本文关键词： 交叉变轮距转向单元优化设计有限元虚拟样机　出处：《青岛理工大学》2016年硕士论文　论文类型：学位论文

【摘要】：常见车辆一般为定轮距结构,而对于农用车辆来说,轮距可调能够扩大作业对象范围,大大提升利用效率。目前,国内可调轮距的车辆一般是人工有级调节的,在无级变轮距技术领域的研究较少;而国外很多农用车辆已应用变轮距技术,如自走式喷药机系列,这些车辆一般自动化程度较高,价格昂贵,且使用和维修比较复杂,因此,在国内推广应用受到极大限制。通过对变轮距技术的相关研究,提出了一种“交叉变轮距”技术,即将传统前后平行式车桥改为交叉布置,通过改变车桥间夹角来间接实现轮距的无级调节。由于车辆转向性能的优劣是评价作业质量高低的一个重要标准,故对交叉变轮距底盘转向机构的运动学研究是十分必要且极具价值的。首先,研究了交叉变轮距底盘转向原理。根据交叉变轮距底盘轮距无级可变的特点,将传统的定参数转向机构改为参数可变的“转向单元”,使转向特性能够随着轮距的改变而变化,从而保证车辆的正常转向。对转向单元进行优化设计,应用机构学相关理论,对转向单元建立平面几何模型,根据阿克曼转向原理推导出交叉变轮距车辆理想转向内外轮转角关系;利用平面几何模型求解出实际内外轮转角关系。建立转向单元的多参数优化目标函数,确定相关约束条件,借助Matlab软件对转向单元进行优化设计。其次,对转向横拉杆的强度和稳定性校核。转向横拉杆是决定转向单元能否正常工作的关键部件,在Ansys中对转向横拉杆进行有限元分析,观察其应力分布及变形情况,确保能够满足强度和稳定性的要求。最后,结合整车结构的设计参数,在Adams中建立虚拟样机模型,对交叉变轮距车辆的转向特性进行运动学研究。通过运动仿真得到实际内外轮转角变化曲线,再对比分析阿克曼理想转角变化曲线,验证建模、仿真及优化设计结果的准确性。
[Abstract]:Common vehicles are usually fixed wheel spacing structure, but for agricultural vehicles, the adjustable wheel spacing can expand the scope of operation objects, greatly improve the utilization efficiency. At present, domestic adjustable wheel distance vehicles are generally manually adjusted. The research in the field of stepless wheel spacing technology is less; Many foreign agricultural vehicles have applied variable wheel distance technology, such as self-propelled spraying machine series, these vehicles are generally high degree of automation, expensive, and the use and maintenance of more complex, so. Through the research on the technology of variable wheel distance, a kind of "cross variable wheel distance" technology is put forward, that is, the traditional front and rear parallel vehicle bridge is changed to cross arrangement. The stepless adjustment of wheel distance is realized indirectly by changing the angle between the vehicle and the axle. The steering performance of the vehicle is an important criterion to evaluate the operation quality. Therefore, it is necessary and valuable to study the kinematics of cross-variable wheel pitch chassis steering mechanism. Firstly, the principle of cross-variable wheel pitch chassis steering is studied. By changing the traditional fixed parameter steering mechanism into a variable parameter steering unit, the steering characteristics can change with the change of wheel spacing, thus ensuring the normal steering of the vehicle and optimizing the design of the steering unit. Based on the theory of mechanism, the plane geometry model of steering unit is established, and the ideal steering angle of cross variable wheel distance vehicle is deduced according to Ackermann steering principle. Using the plane geometry model to solve the actual internal and external wheel rotation angle, the multi-parameter optimization objective function of steering unit is established, and the relative constraint conditions are determined. The Matlab software is used to optimize the design of steering unit. Secondly, the strength and stability of steering bar are checked. The steering rod is the key component to determine whether the steering unit can work properly. Finite element analysis of steering bar is carried out in Ansys to observe its stress distribution and deformation to ensure that it can meet the requirements of strength and stability. Finally, combined with the design parameters of the whole vehicle structure. A virtual prototype model is established in Adams to study the steering characteristics of cross-wheeled vehicles. The actual curves of internal and external wheel angle change are obtained by motion simulation. The accuracy of modeling, simulation and optimization design is verified by comparing and analyzing Ackerman's ideal angle curve.
【学位授予单位】：青岛理工大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：U463.4

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