Parallel Link Hub Layout for Compact Coaxial Speed Reduction
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Solution Overview
Problem
Existing parallel link mechanisms face challenges in achieving a wide operating range with high accuracy and speed while maintaining a compact size, particularly when the speed reduction mechanism has coaxial input and output shafts, leading to increased radial dimensions and interference with link mechanisms.
Innovation Solution
A link operating device with a proximal-end-side link hub, a distal-end-side link hub, and three or more quadric chain link mechanisms, where the proximal-side end link member includes a bent portion and rotational connection bodies, and the speed reduction mechanism is disposed between these bodies with coaxial input and output shafts, allowing for a compact configuration without radial expansion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the speed reduction mechanism is disposed radially outward of the parallel link mechanism, then the motor and speed reduction mechanism can be positioned, but the size in the radial direction is increased and interference with link mechanisms occurs
Solution Approach 1:
The speed reduction mechanism is nested within the space formed by the bent portion of the proximal-side end link member, specifically disposed between the imaginary planes extending the radially inner edge and radially outer edge of the bent portion. This nesting approach allows the speed reduction mechanism to occupy otherwise unused space within the link mechanism structure, avoiding radial expansion while preventing interference with link mechanisms.
2Ease of manufacture
If the parallel link mechanism is configured with simple structure, then manufacturing is easier, but the operating angle of each link is small and the dimension of the entire mechanism is increased
Solution Approach 1:
The proximal-side end link member incorporates a bent portion that utilizes three-dimensional spatial arrangement rather than simple linear configuration. By bending the link member and defining a rotational connection portion at the bent location, the mechanism achieves compact radial dimensions while maintaining adequate operating angles, effectively using vertical and radial dimensions to reduce overall mechanism footprint.
3Ease of manufacture
If the parallel link mechanism is configured with simple structure, then manufacturing is easier, but the rigidity of the entire mechanism is low and weight capacity is limited
Solution Approach 1:
The proximal-side end link member is constructed as a composite structure combining a bent portion (which may be formed from bent tube or plate material) and a rotational connection portion (which may be a separate component). This composite construction allows optimization of rigidity in critical areas while maintaining manufacturing feasibility, achieving high rigidity and weight capacity without overly complex configuration.
4Volume of moving object
If the speed reduction mechanism has coaxial input and output shafts, then the mechanism can be compact, but the configuration is not applicable when axes intersect and radial dimension increases
Solution Approach 1:
The bent portion of the proximal-side end link member is specifically designed with differentiated radial edges (radially inner edge and radially outer edge) to create an asymmetric spatial configuration. This local quality variation in the bent portion's geometry creates the necessary space to accommodate the coaxial speed reduction mechanism, allowing compact design without radial expansion by optimizing the local spatial arrangement rather than requiring uniform dimensional reduction throughout.
Data Source
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AI summary
In the link operating device, a distal-end-side link hub is connected to a proximal-end-side link hub so as to be changeable in position relative thereto via at least three link mechanisms. Each link mechanism includes a proximal-side end link member, a distal-side end link member, and a center link member. Position-controlling actuators and speed reduction mechanisms are provided to two or more of the link mechanisms. The proximal-side end link member includes a bent portion and a pair of rotational connection bodies disposed at one end of the bent portion. The speed reduction mechanism is disposed between the pair of rotational connection bodies, and includes an output shaft fixed to one of the rotational connection bodies, and an input shaft rotatably supported by the other one of the rotational connection bodies.