摘要本文研究的平衡机构所平衡的对象：并联平台[4]，它可以被定义为：固定平台和活动平台之间通过两个或两个以上的独立的运动链相连接，机构具有两个或两个以上自由度，且以并联方式驱动的一种闭环机构。

本文所研究的并联平台为钢带并联平台[7]，下平台（动平台）在最初状态下，是与水平面成45°倾斜角的，并且可以完成±45°的运动范围。在下平台近于竖直的时候，重力与支撑钢带之间的夹角将近有90°，易使支撑钢带变形，影响并联机器人的精度和使用寿命。51248

所以需要设计重力平衡机构，对下平台（动平台）上的载荷进行平衡，以改善支撑钢带的受力状况。本文从两个方面对平衡机构进行了设计，第一方面是对动平台的整体重心寻找机构的设计，第二方面是对平面内二维随动机构[10]的设计。

第一部分的设计：通过半圆拱形导轨与导轨末端的自由转动，构成球形工作空间。根据球面特性，当牵引力的作用点在球面时牵引力的作用方向总是与球的重力方向相反且在同一直线上，从而可以自定重心作用线，达到动态平衡重力的目的。

第二部分的设计：上端牵引力的作用点总是不断在二维平面内运动的，它的作用点集合为球面在水平面的投影，即上端作用点可以在一个圆形平面内自由移动。本文最终采用的是Rα结构方案。

毕业论文关键词：并联平台机构；重心寻找；二维随动机构；重力平衡[14]

Abstract In this paper, the balance of institutions balance of objects: the parallel platform, which can be defined as: a fixed platform and moving platform passed between two or more of the independent movement of the chain is connected to two or more institutions have freedom degrees, and driven in parallel a closed-loop mechanism.

Studied in this paper parallel parallel platform is a steel platform, the platform (moving platform) in the initial state, are inclined by 45 ° with the horizontal angle, and can complete range of motion of ± 45 °. Next platform when nearly vertical, gravity and the angle between the support strip is nearly 90 °, easy to make the support strip deformation, affecting parallel robot accuracy and service life.

So gravity balance mechanism needs to be designed for the next platform (moving platform) to balance the load on to improve the support strip force status. In this paper, two aspects were designed to balance the body, the first aspect is the overall center of gravity of the moving platform looking for mechanism design, the second aspect is the two-dimensional plane with the actuator design.

The first part of the design: semicircular arcuate rail and the guide rail at the end of free rotation, constituting the spherical work space. According to the spherical characteristics, when the traction point of the sphere when the acting direction of traction with the ball is always opposite to the direction of gravity, and in the same line, which can be the center of gravity from the line of action, to achieve the purpose of dynamic balance of gravity.

The second part of the design: the upper end point of the traction force constantly move within the two-dimensional plane, and its set point of the spherical projection in a horizontal plane, i.e. the upper end point of a circular plane can move freely. This paper uses a Rα final structure of the program.

Keywords: Parallel Mechanism；Seeking the center of gravity；Two-dimensional kinematic mechanism；gravity balance

目  录

第一章 绪论 1

1.1 并联机构简介 1

1.1.2并联机构的发展历程 1

1.1.3并联机构的优势