Link Actuating Device with Interlocking Unit for Two Degrees of Freedom
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Solution Overview
Problem
Conventional link actuating devices have a large outer diameter, are difficult to assemble, and costly, with limited rigidity and mobility, making them unsuitable for compact applications and human joint assistance, particularly in the medical field where they struggle to provide two degrees of freedom for complex movements.
Innovation Solution
A link actuating device with two sets of three-link-chain link mechanisms and an interlocking unit, allowing for two degrees of freedom while maintaining a compact configuration and preventing interference, using rolling bearings and actuators to enhance rigidity and mobility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If three sets of link mechanisms are used to define the attitude of the output side link hub, then the device can achieve the required two degrees of freedom, but the outer diameter becomes large and the structure becomes complex
Solution Approach 1:
The patent merges two sets of link mechanisms into a single integrated structure where the intermediate link serves both mechanisms. This consolidation reduces the overall outer diameter while maintaining the two degrees of freedom capability, as the shared intermediate link eliminates redundant components that would otherwise increase the device volume.
Solution Approach 2:
The intermediate link performs multiple functions simultaneously: it connects to both input and output side end links, provides revolute pairs for both link mechanisms, and enables the two degrees of freedom motion. This multi-functionality reduces the total number of components needed, thereby reducing the outer diameter of the device.
2Adaptability or versatility
If three sets of link mechanisms are used, then the two degrees of freedom are achieved, but the device becomes costly and difficult to assemble
Solution Approach 1:
By combining two link mechanisms that share a common intermediate link, the patent reduces the total number of components from three sets to two sets. This reduction simplifies the assembly process and lowers manufacturing costs while preserving the two degrees of freedom capability through the shared intermediate link structure.
3Ease of operation
If conventional CPM devices with one degree of freedom are used, then the structure is simple, but they cannot provide complex movements required for human joint assistance
Solution Approach 1:
The patent transitions from a static one-degree-of-freedom structure to a dynamic two-degree-of-freedom structure that can adapt to complex human joint movements. The two sets of link mechanisms with shared intermediate link enable dynamic motion in two independent directions, providing the flexibility needed for human joint assistance while maintaining structural efficiency.
4Volume of moving object
If two sets of link mechanisms are used with crossing revolute pair axes, then the outer diameter is reduced, but interference between mechanisms may occur
Solution Approach 1:
The patent positions the two sets of link mechanisms asymmetrically with crossing revolute pair axes, where the first revolute pair axes of each set are located on the same plane but at different orientations. This asymmetric arrangement reduces the outer diameter while the careful geometric design prevents interference between the mechanisms during operation.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The device achieves a compact design with improved rigidity and cost-effectiveness, enabling easy assembly and effective two-degree-of-freedom movement, suitable for human joint assistance and complex operations.
Implementation Method 1
rolling bearings that rotatably support the input side and output side end links relative to the input side and output side link hubs
Data Source
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AI summary
A link actuating device (1) includes input side and output side link hubs (2, 3), and two sets of link mechanisms (4A, 4B). Each of the link mechanisms (4A, 4B) is a three-link-chain link mechanism including four revolute pairs, and includes input side and output side end links (5, 6) rotatably connected to the input side and output side link hubs (2, 3) and an intermediate links (7) rotatably connected to input side and output side end links (5, 6). The link mechanism (4A, 4B) have a positional relationship in which the revolute pair axes (O1A, O1B, 02A, and 02B) between the link hubs (2, 3) and the end links (5, 6) are located on the same plane and cross each other. At least one of the two sets of link mechanisms (4A, 4B) is provided with interlocking unit (9) that interlocks the input side end link (5) and the output side end link (6) to each other so as to be rotationally displaced.