3R-3URU可展单元机构及其在构架式可展天线中的应用

提出了一种空间单自由度(DOF)可展单元机构3R-3URU。首先,基于螺旋理论和修正的G-K公式分析了RURUR单闭环机构的自由度,建立了该机构中主动关节和被动关节速度之间的解析关系式,基于此关系式和3个RURUR机构共用首尾转动副的结构特点推导了3R-3URU单元机构的自由度,得到了3R-3URU机构具有1个自由度时各运动副的方向和位置满足的几何关系式。其次,将3R-3URU机构应用于3RR-3RRR四面体可展单元及其组成的球面构架式可展天线中,得到了具有收拢和调姿两种自由度的新型可展机构。最后,利用Adams软件对3R-3URU可展单元机构的自由度和其在四面体构架式可展天线中的应用进行了仿真验证。该3R-3URU可展单元机构具有单自由度、铰链种类少、结构简单等优点,可用于曲面构架式可展天线的支撑机构中,实现大折叠比。

Deployable unit 3R-3URU and its application in deployable truss antenna

A spatial deployable unit 3R-3URU with one Degree of Freedom (DoF) is proposed .The DoF of the single closed-loop mechanism RURUR is analyzed ,based on the screw theory and the modified G-K formula .The analytical expres-sion for the velocities of active joints and passive joints of the mechanism RURUR are then established .According to the ve-locity expression and the structural characteristic that three RURUR mechanisms share their first and last revolute joints ,the DoF of the 3R-3URU mechanism is derived .The geometrical relationship among the positions and directions of all joints is al-so obtained when the 3R-3URU mechanism has one DoF .Novel deployable mechanisms are obtained by applying the 3R-3URU mechanism to the 3RR-3RRR tetrahedral unit and a deployable truss antenna composed of the tetrahedral units ,and the novel mechanisms have two types of DoFs:movement and orientation adjustment .DoF analysis and application of the 3R-3URU deployable unit are verified by the Adams software .The proposed deployable unit 3R-3URU has the advantages of one DoF ,simple structure ,and single type of joints ,and can be applied to the supporting mechanism of deployable truss anten-nas with a curved surface to achieve a large folding ratio .