考虑关节间隙的平面2R开环和5R闭环机构定位误差的研究

发布时间：2018-07-03 00:48

本文选题：平面机构 + 静态误差　；参考：《哈尔滨工业大学》2017年硕士论文

【摘要】：随着高科技的快速发展,航空航天工业、精密机械、医疗器械和工业自动化等行业对机构的位置精度有了更高的要求,特别是高速、高精度和高可靠性场合,机构的定位精度是衡量其工作性能的重要指标之一。关节间隙容易引起运动副元素的碰撞、摩擦和磨损,降低机构的定位精度和运行稳定性。因此,考虑机械系统中的关节间隙,本文以平面2R开环和5R闭环机构为研究对象,从不同的角度深入研究关节间隙对机构定位误差和动力学特性的影响,为机构可靠性分析、定位误差的补偿等提供理论基础。本文主要包括以下内容:针对从运动学角度考虑关节间隙的平面机构,建立了平面2R开环和5R闭环机构的运动学误差分析模型。将转动关节间隙看作成无质量杆,利用几何法,分别推导出了两个机构末端执行器的定位误差公式,以误差指数作为机构定位精度的评价指标,通过Matlab仿真出了机构末端点定位误差在工作区间内的变化规律。针对静力和惯性力作用下考虑关节间隙的平面机构,建立了考虑关节间隙的平面2R开环和5R闭环机构的误差分析模型。对两个机构分别进行了静力学分析,用牛顿-欧拉法建立了两个机构的动力学方程,求解出了各关节的约束反力;建立了转动关节局部误差模型,运用虚功原理建立了末端执行器定位误差和局部误差的映射关系,通过Matlab仿真分析了两个机构分别在静力和惯性力作用下的定位误差在位形空间上的分布情况。针对关节间隙引起的运动副元素的碰撞和摩擦现象,建立了转动关节间隙的矢量模型和数学模型,引入碰撞力和摩擦力模型,利用拉格朗日乘子法分别建立了考虑间隙的平面2R开环和5R闭环机构的动力学模型,通过Matlab仿真分析了不同的间隙尺寸和关节转速对两个机构动力学特性的影响。以位置误差和速度振荡可靠指数作为机构运动精度的评价指标,分析了不同的关节间隙和关节转速对平面两个机构运动精度的影响。
[Abstract]:With the rapid development of high-tech, the aerospace industry, precision machinery, medical devices and industrial automation industries have higher requirements for the accuracy of the position of the organization, especially in high-speed, high-precision and high-reliability situations. The positioning accuracy of the mechanism is one of the important indexes to measure its working performance. The joint clearance can easily cause collision, friction and wear of the moving pair elements, and reduce the positioning accuracy and operation stability of the mechanism. Therefore, considering the joint clearance in the mechanical system, this paper takes the planar 2R open-loop and 5R closed-loop mechanism as the research objects, and studies the effect of the joint clearance on the positioning error and dynamic characteristics of the mechanism from different angles, which is the reliability analysis of the mechanism. The compensation of positioning error provides the theoretical basis. The main contents of this paper are as follows: the kinematics error analysis models of planar mechanisms with planar 2R open loop and 5R closed loop are established for the planar mechanism which considers the joint clearance from the kinematics point of view. The rotation joint clearance is regarded as a mass free rod. By using geometric method, the positioning error formulas of the end actuators of two mechanisms are derived, and the error index is taken as the evaluation index of the positioning accuracy of the mechanism. Through Matlab simulation, the change rule of the end point positioning error in the working interval is obtained. An error analysis model for planar mechanisms with joint clearance under static and inertial forces is established, in which the planar 2R open-loop and 5R closed-loop mechanisms consider the joint clearance. The static analysis of the two mechanisms is carried out, the dynamic equations of the two mechanisms are established by Newton-Euler method, the constrained reaction forces of each joint are solved, and the local error model of the rotational joint is established. The mapping relationship between the positioning error and the local error of the end effector is established by using the virtual work principle. The distribution of the positioning error in the configuration space of the two mechanisms under the action of static force and inertial force is analyzed by Matlab simulation. Aiming at the collision and friction of moving pair caused by joint clearance, the vector model and mathematical model of rotational joint clearance are established, and the collision force and friction model are introduced. The dynamic models of planar 2R open-loop and 5R closed-loop mechanisms with clearance are established by using Lagrange multiplier method, respectively. The effects of different clearance sizes and joint rotational speeds on the dynamic characteristics of the two mechanisms are analyzed by Matlab simulation. Based on the position error and reliability index of velocity oscillation, the effects of different joint clearance and rotation speed on the kinematic accuracy of two planar mechanisms are analyzed.
【学位授予单位】：哈尔滨工业大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TH112

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