Parallel Link Hub Layout With Coaxial Reducer Integration
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Solution Overview
Problem
Existing link operating devices 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, as they tend to increase the radial dimension and interfere with the link mechanisms.
Innovation Solution
A link operating device with a proximal-end-side link hub, a distal-end-side link hub, and at least three link mechanisms, where the proximal-side end link member includes a bent portion and a rotational connection portion with coaxial speed reduction mechanisms disposed between rotational connection bodies, allowing the speed reduction mechanism to be integrated without increasing the radial dimension, and enabling a compact and rigid configuration.
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 the operating range is limited
Solution Approach 1:
The speed reduction mechanism is repositioned from a radial arrangement to an axial arrangement along the input shaft. The input shaft extends in the radial direction while the speed reduction mechanism is disposed axially, changing the dimensional orientation from radial to axial to resolve the conflict between compact radial size and operational freedom.
Solution Approach 2:
The speed reduction mechanism is integrated within the link mechanism structure itself, with the input shaft of the speed reduction mechanism coupled to the proximal-side end link member. This nesting allows the speed reduction mechanism to be positioned without increasing the overall radial dimension of the device.
2Device complexity
If the parallel link mechanism uses a simple configuration with small operating angles, then the structure is simplified, but the link length must be increased to achieve wide operating range, resulting in increased device size
Solution Approach 1:
The link mechanism is segmented into multiple components including the proximal-side end link member, distal-side end link member, center link member, and speed reduction mechanism. This segmentation allows each component to be optimized independently, enabling compact link lengths while maintaining wide operating range through the coordinated action of multiple segments.
Solution Approach 2:
The operating parameters of the link mechanism are changed by introducing the speed reduction mechanism with specific reduction ratios. This allows the mechanism to achieve wide operating range and high positioning accuracy without increasing link length, as the speed reduction mechanism enables precise control of the link angles and positions.
3Length of stationary object
If the parallel link mechanism is made compact, then the radial dimension is reduced, but the rigidity decreases and weight capacity is limited
Solution Approach 1:
The link mechanism employs composite structural design combining multiple link members (proximal-side end link member, distal-side end link member, center link member) with the speed reduction mechanism. This composite structure achieves high rigidity and weight capacity in a compact form by distributing loads across multiple components and utilizing the mechanical advantage of the speed reduction mechanism.
Solution Approach 2:
The speed reduction mechanism is merged with the link mechanism structure, with the input shaft coupled to the proximal-side end link member and the output shaft to the distal-side end link member. This merging creates a unified structure that maximizes rigidity and load-bearing capacity within a compact radial dimension.
Data Source
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.