全约束空间三自由度索驱动并联机构运动仿真

发布时间：2018-11-08 09:26

【摘要】：通常情况下,电缆驱动并联机构(CDPMs)是一种特殊类型的由电缆驱动而不是刚性体驱动的并联机构。由于电缆的单侧传动性能,CDPMs需要冗余驱动维持大于零的绳索张力。作为并联机器人中的一种,CDPMs有负载能力强,刚度大,效率高等优点。此外,CDPMs克服了刚性并联机器人工作空间小的缺点。不同于刚性连接,电缆长度可在很大的范围内变化,从而增大CDPMs工作区。本文重点研究了CDPMs静力学、运动学、动力学、张力分配、工作空间、控制和仿真问题,旨在提高CDPMs的运动学正反解、静态位姿、可行轨迹和空间规划精度的问题。为了研究这些问题,搭建由四根绳索牵引的空间三自由度CDPMs模型。在几乎所有的CDPR/CDPM研究工作中,机构的结构被布置成使得所有的电缆连接在平台的上边缘或者下边缘,以使平台能够自由移动覆盖大部分工作区。然而,也有一些应用领域,其不一定需要在底部没有电缆或自由旋转的平台,而是用一根电缆固定在底部。因此,在本论文中,有一根电缆放置在机构的底部。由于CDPMs的运动学正解是闭环结构,与运动学反解相比相对困难。在本论文中,应用牛顿-拉夫逊数值方法,通过建立牛顿-拉夫逊矩阵和雅可比矩阵之间的映射来改进其计算性能,以获得运动学正解。为了帮助这个过程,开发了一种算法。此外,对于三自由度空间类型CDPMs机构,计算运动学反解即为给定平台的位置计算电缆的长度变化。CDPMs的另一个显着特点是电缆的单向性,即电缆只能拉而不推。因此,CDPMs需要冗余驱动来保持电缆的正向张力。确保CDPMs中适当的张力是很重要的,这样使得移动平台的姿态可以通过至少一个适当的正电缆张力来完全约束。在本论文中,力闭环、零空间法和分割工作空间方法均可以被用来获得CDPMs的正张力解决方案。此外,本研究工作也涵盖了3自由度空间CDPMs的动力学分析与控制。本论文论述了应用具有内循环和外循环的级联控制方案。内环用于控制机构的位置,而外环控制张力。此外,本论文也使用Simulink,SimMechanics和SolidWorks进行编程、建模和运动模拟。
[Abstract]:In general, the cable driven parallel mechanism (CDPMs) is a special type of parallel mechanism driven by cable rather than rigid body. Because of the single-side transmission performance of the cable, CDPMs needs redundant drive to maintain rope tension greater than zero. As a parallel robot, CDPMs has many advantages, such as high load capacity, high stiffness and high efficiency. In addition, CDPMs overcomes the disadvantage of small workspace of rigid parallel robot. Unlike rigid connections, cable lengths can vary over a wide range, increasing the CDPMs workspace. This paper focuses on the problems of CDPMs statics, kinematics, dynamics, tension distribution, workspace, control and simulation. The purpose of this paper is to improve the kinematics inverse solution, static pose, feasible trajectory and spatial planning accuracy of CDPMs. In order to study these problems, a three-degree-of-freedom (CDPMs) model with four ropes was built. In almost all CDPR/CDPM studies, the structure of the mechanism is arranged so that all cables are connected to the upper or lower edges of the platform so that the platform can move freely to cover most of the work areas. However, there are also areas of application where there is not necessarily a cable at the bottom or a freely rotating platform, but a cable attached to the bottom. Therefore, in this paper, there is a cable placed at the bottom of the mechanism. Because the positive kinematics solution of CDPMs is a closed loop structure, it is relatively difficult compared with the inverse kinematics solution. In this paper, Newton-Raphson numerical method is used to improve the computational performance of Newton-Raphson matrix and Jacobian matrix by establishing the mapping between Newton-Raphson matrix and Jacobian matrix to obtain the positive kinematics solution. In order to help this process, an algorithm is developed. In addition for the 3-DOF spatial type CDPMs mechanism the inverse solution of computational kinematics is to calculate the length change of the cable for the position of the given platform. Another significant feature of CDPMs is the unidirectionality of the cable which means that the cable can only be pulled but not pushed. Therefore, CDPMs requires redundant drivers to maintain the forward tension of the cable. It is important to ensure proper tension in the CDPMs so that the posture of the mobile platform can be fully constrained by at least one appropriate positive cable tension. In this paper, the force closed loop, zero space method and partition workspace method can be used to obtain the normal tension solution of CDPMs. In addition, the dynamic analysis and control of 3 DOF spatial CDPMs are also covered in this paper. In this paper, a cascade control scheme with internal and external cycles is discussed. The inner ring is used to control the position of the mechanism, while the outer loop controls the tension. In addition, Simulink,SimMechanics and SolidWorks are used for programming, modeling and motion simulation.
【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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