Quaternion Joint Offset Pulley Design Eliminates Wire Guides
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Solution Overview
Problem
The existing quaternion joint design with a moving pulley structure and obliquely hung wires is prone to wire dislodgment, leading to increased component weight and mechanism size due to the need for wire guides and support structures.
Innovation Solution
The quaternion joint design incorporates a configuration where the rotation shafts of the first and second pulleys are offset, allowing the pulleys to be arranged such that the wire is not obliquely hung, eliminating the need for wire guides and reducing the mechanism's size and weight.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a moving pulley structure with obliquely hung wires is employed, then the quaternion joint can achieve its rotational function, but the wire can easily come off the pulley requiring additional guide components that increase weight
Solution Approach 1:
The patent applies asymmetry by offsetting the rotation shafts of the first and second pulleys from the swing shafts. Specifically, the rotation shaft of the first pulley is offset from the swing shaft of the first pulley, and the rotation shaft of the second pulley is offset from the swing shaft of the second pulley. This asymmetric arrangement changes the geometric relationship between the pulleys and wires, allowing the wires to be hung vertically rather than obliquely, thereby eliminating the need for guide components and reducing weight while maintaining wire retention.
2Device complexity
If two degrees of freedom of the pulley are coaxially arranged, then the pulley structure can be simplified, but the mechanism size increases
Solution Approach 1:
The patent applies dimensionality change by transitioning from a coaxial arrangement (one-dimensional alignment) to an offset arrangement where rotation shafts are positioned at different locations relative to swing shafts. This spatial reconfiguration in multiple dimensions allows the mechanism to maintain compact size while achieving the necessary two degrees of freedom for quaternion joint rotation.
3Weight of moving object
If the rotation shafts of first and second pulleys are offset, then wire guides can be eliminated reducing weight and size, but the pulley arrangement becomes more complex
Solution Approach 1:
The offset pulley shaft arrangement is designed to be self-configuring, where the geometric relationship between the offset rotation shafts and swing shafts automatically determines the wire hanging path. The system uses its own structural parameters (offset distances and angles) to achieve the desired wire alignment without requiring external guide components, thereby reducing weight while the complexity is contained within the inherent geometric design of the pulley system.
Data Source
AI summary
A quaternion joint includes a first member, a second member rotatably connected to the first member through links, a plurality of first pulleys provided on the end face of the first member so that the first pulleys are able to swing, a plurality of second pulleys provided on the end face of the second member facing the end face of the first members so that the second pulleys correspond to the first pulleys and so that the second pulleys are able to swing, and a plurality of wires hung between the first pulleys and the second pulleys corresponding to the first pulleys. A rotation shaft of the first pulley is offset from a rotation shaft of the second pulley corresponding to the first pulley in a state in which the rotation shaft of the first pulley is rotated around a direction in which the wire is extended.