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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。
A 3 DOF-expandable unit mechanism 3R-3URU is proposed. First, based on the spiral theory and the modified GK formula, the degree of freedom of RURUR single-closed-loop mechanism is analyzed and the analytical relationship between the active joint and the passive joint speed is established. Based on the relationship, the three RURUR mechanisms share the same rotation The structural characteristics of the secondary structure of the 3R-3URU have been deduced. The geometric relations of the directions and positions of the pairs of 3R-3URU with one degree of freedom are obtained. Secondly, the 3R-3URU mechanism is applied to the 3RR-3RRR tetrahedral expansile unit and the spherical scaffolding antenna with the same structure, and a new type of expandable mechanism with two degrees of freedom of folding and adjusting is obtained. Finally, the degree of freedom of the 3R-3URU expandable unit mechanism and its application in the tetrahedral scalable antenna system are verified by using Adams software. The 3R-3URU expandable unit has the advantages of single degree of freedom, few types of hinges, simple structure, etc., and can be used in the supporting mechanism of a curved frame-type extendable antenna to realize a large folding ratio.