Parallel Link Hub Mechanism for Wide-Range Rigid Actuation
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Solution Overview
Problem
Existing link actuation devices face challenges in achieving a compact configuration with a wide operating range while maintaining rigidity and load capacity, particularly in medical and industrial applications where precise operation over a wide range is required.
Innovation Solution
A link actuation device with a parallel link mechanism that includes a proximal-end-side link hub, a distal-end-side link hub, and three or more link mechanisms, where the central axes of revolute pairs intersect at a single point, allowing for arbitrary change in the distance between spherical links and control of the posture and distance through actuators and a control unit, using equations to calculate and achieve specific rotation angles and postures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the link length is increased to provide a large operation range for the travelling plate, then the operation range is improved, but the device size increases and rigidity decreases
Solution Approach 1:
The patent employs a parallel link mechanism with multiple links (first link, second link, third link, fourth link) connected through rotational joints, allowing the system to dynamically adjust its configuration. The traveling plate can achieve a wide operation range through coordinated rotation of multiple links rather than relying on a single long link, thus maintaining compact device dimensions while providing extensive operational capability.
Solution Approach 2:
The mechanism divides the motion transmission into multiple segmented links instead of using a single long link. Each link (first, second, third, fourth link) has a relatively short length, but their coordinated movement through rotational joints enables the traveling plate to cover a large operation range. This segmentation resolves the contradiction by achieving extended reach without proportionally increasing overall device size.
2Adaptability or versatility
If the link length is increased to provide a large operation range for the travelling plate, then the operation range is improved, but the rigidity of the mechanism decreases
Solution Approach 1:
The parallel link mechanism with multiple rotational joints allows the system to maintain rigidity through its structured geometry. The coordinated rotation of multiple short links provides structural stability while achieving a wide operation range, avoiding the rigidity loss associated with single long links.
Solution Approach 2:
By segmenting the mechanism into multiple short links (first, second, third, fourth links) connected through rotational joints, the patent maintains higher rigidity in each individual link while achieving extended operation range through their coordinated movement. This segmentation prevents the rigidity degradation that would occur with a single long link.
3Adaptability or versatility
If the link length is increased, then the operation range is improved, but the load capacity of the travelling plate is restricted to a small value
Solution Approach 1:
The parallel link mechanism distributes mechanical loads across multiple links and joints during operation. This dynamic load distribution allows the traveling plate to maintain high load capacity even while achieving a wide operation range, as the force is shared among the first, second, third, and fourth links rather than concentrated in a single long link.
4Volume of stationary object
If a compact configuration is achieved, then the device size is reduced, but the operating range is limited
Solution Approach 1:
The patent achieves a compact configuration through its parallel link mechanism structure, where multiple short links are arranged in parallel. The traveling plate achieves an extended operating range through the coordinated dynamic movement of these links, allowing the device to maintain a compact form factor while providing extensive operational capability.
Solution Approach 2:
By segmenting the mechanism into multiple short parallel links (first, second, third, fourth links), the patent achieves a compact overall device size while the coordinated movement of these segmented links enables a wide operating range for the traveling plate.
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 configuration with a wide operating range, allowing for precise control of the distal-end-side link hub's posture and distance from the proximal-end-side link hub, enhancing the device's ability to handle tools with varying loads and maintain stability across different operating conditions.
Implementation Method 1
a central axis of a revolute pair of the proximal-side end link member and the proximal-side intermediate link member intersects with a central axis of a revolute pair of the distal-side end link member and the distal-side intermediate link member
Data Source
AI summary
A link actuation device includes a proximal-end-side link hub, a distal-end-side link hub, three or more link mechanisms each coupling the link hubs such that a posture of the distal-end-side link hub can be changed relative to the proximal-end-side link hub. Each link mechanism includes a proximal-side end link member, a proximal-side intermediate link member, a distal-side intermediate link member, and a distal-side end link member. Actuators for arbitrarily changing the posture and a distance from the distal-end-side link hub to the proximal-end-side link hub are provided to three or more link mechanisms of the three or more link mechanisms. A control unit calculates a rotation angle of the proximal-side end link member according to a targeted posture of the distal-end-side link hub and a targeted distance between the centers of the spherical links, and controls the respective actuators so as to attain the calculated rotation angle.