3R-3RSR single-degree-of-freedom tetrahedron expandable unit

Abstract

The invention discloses a 3R-3RSR single-degree-of-freedom tetrahedron expandable unit, which comprises a top face plate, three swing rods with equal lengths, six connecting rods, nine rotation pairs and three ball pairs, wherein the upper ends of the three swing rods are connected with the top face plate through three coplanar rotation pairs; the axis of each rotation pair is vertical to a plane which is determined by an intersection point of the upper ends of the three swing rods, a triangular circumcenter of the tetrahedron unit and the lower end point of the corresponding swing rod; the lower end of each swing rod is respectively connected with two folding rods through two rotation pairs; each folding rod comprises two connecting rods with equal lengths and one ball pair; the unit is in a completely expanded state; the axes of the rotation pairs at two ends of each folding rod are parallel to each other and are vertical to the connected line of the centers of two rotation pairs; and the unit can be folded or expanded by driving any rotation pair. The 3R-3RSR single-degree-of-freedom tetrahedron expandable unit has the advantages of being single in degree of freedom, few in hinges, simple in structure, small in folding volume and the like, and is suitable for a large-caliber truss-type expandable antenna.

Description

technical field [0001] The invention relates to an expandable mechanism, in particular to a single-degree-of-freedom tetrahedron expandable unit. Background technique [0002] The expandable mechanism originated in the 1960s. It is integrated with prefabricated units and can switch between the initial compact configuration and the expanded configuration in the working state. It generally has two stable states: a fully folded state and a fully expanded state ( working status). In order to meet the high-gain requirements of spaceborne antennas for key aerospace technologies such as electronic reconnaissance, data relay, and ground navigation, directly increasing the reflector aperture is the most effective way, but limited by the payload space of the vehicle, These large-aperture reflectors inevitably adopt an expandable mechanism. During storage and transportation, they are in a fully retracted state, and they will gradually expand to a working state after being launched int...

AI Technical Summary

Problems solved by technology

[0005] The basic expandable units of most truss reflectors are composed of hinges and connecting rods, and factors such as gaps and friction in the hinges are likely to cause instability of the expandable mechanism, poor positioning accuracy, failure to expand or retract, etc.

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