两种三自由度并联角台机构的转动空间分析

Rotation Workspace Analysis of Two 3-DOF Cubic Parallel Mechanisms

传统的三自由度转动并联机构的各分支之间存在有多个空间汇交于一点的转动副轴线。这种严格的几何条件给机构的加工制造带来很大的难度,增加制造成本,且不容易保证加工精度,严重制约这类机构的应用。为解决上述问题,提出一类新型的无汇交轴线的三自由度转动并联机构。这类机构的动平台具有三个转动自由度,能够实现空间任意给定姿态,且各分支之间没有空间汇交的转动副轴线,很容易进行加工制造和保证制造精度。通过对两种具有这类运动特点的三自由度并联角台机构进行运动学求解和转动空间分析,可以看出这类机构能够实现期望的三个转动自由度,且具有较大的转动空间,可以用作姿态控制装置。

Among the branches of the traditional three degrees of freedom （3-DOFs） rotational parallel mechanism, there are multi revolute joint axes intersecting at one common point. This strict geometric requirement brings much difficulty to the manufacturing, which will increase the manufacturing cost and make it hard to ensure the machining accuracy. So, the applications of this kind of parallel mechanisms are severely restricted. To solve the above-mentioned problem, a new kind of 3-DOF rotational parallel mechanism without intersecting axes is proposed. The moving platform of this kind of parallel mechanism has three rotational freedoms and can realize any given three dimension rotations. Because there are no intersecting axes among the branches, this new kind of rotational parallel mechanism has the advantages of easy manufacturing and the accuracy can be easily ensured. The kinematic solutions and orientation workspaces of two cubic parallel mechanism of this kind are studied which shows that this kind of parallel mechanism can realize the expected 3-DOF rotations and has large rotation workspace. This new kind of rotational parallel mechanism can be used as attitude control device.