Parallel Link Hub Positioning for Accurate Compact Initialization
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Solution Overview
Problem
Existing link actuating devices face challenges in achieving a wide operating range with high accuracy and ease of initialization, particularly due to mechanical backlash and limited weight capacity, which restricts their application in precise and compact configurations.
Innovation Solution
A link actuating device with a two-degrees-of-freedom parallel link mechanism, featuring three or more quadric chain link mechanisms, a posture control drive source, and a positioning member that allows for easy positioning of the distal end side link hub relative to the proximal end side link hub, even in confined spaces with mounted end effectors or cables, by using a storage unit to store the operating position of the posture control drive source and providing a positioning portion on intermediate link members.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the link length is increased to set the operating range of the travelling plate to be large, then the operating range is improved, but the dimensions of the entire mechanism are increased and the size of the device is increased
Solution Approach 1:
The patent employs a parallel link mechanism where multiple link mechanisms are nested within a compact structure. The proximal end side link hub and distal end side link hub are connected through three or more link mechanisms that are arranged in parallel, allowing the mechanism to achieve a large operating range without proportionally increasing the overall device dimensions. This nested arrangement enables efficient space utilization.
2Adaptability or versatility
If the link length is increased to set the operating range of the travelling plate to be large, then the operating range is improved, but the rigidity of the entire mechanism is reduced
Solution Approach 1:
The patent combines three or more link mechanisms in parallel to form a parallel link mechanism. This merging of multiple mechanisms works together to maintain high rigidity while achieving a large operating range. The distributed structure of the parallel links provides both the necessary flexibility for wide operation and the structural strength to maintain precision throughout the range.
3Measurement precision
If the origin positioning member is provided to the proximal end side link hub and the distal end side link hub, then the origin can be positioned with good reproducibility, but it is necessary to dismount the end effector from the distal end side link hub to prevent interference with the origin positioning member or cable
Solution Approach 1:
The patent extracts the origin positioning function from the link hubs and implements it through a separate positioning member that is provided to at least one link member of the link mechanisms. This positioning member can be a detachable element such as a pin or marker that is independent of the end effector mounting structure, allowing origin positioning to be performed without removing the end effector from the distal end side link hub.
4Measurement precision
If a positioning member is provided to position the distal end side link hub in a defined posture, then initialization work can be performed with high accuracy, but the device complexity is increased
Solution Approach 1:
The patent implements origin positioning through the existing link members themselves, which serve dual purposes: they are both structural components of the mechanism and carriers for the positioning function. The positioning portion is provided to at least one link member, allowing the link member to self-position the distal end side link hub in the defined posture without requiring separate complex positioning mechanisms.
Data Source
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AI summary
In a link actuating device (1), a distal end side link hub (13) is coupled to a proximal end side link hub (12) via three or more link mechanisms (14). A posture control drive source (11) configured to arbitrarily change the posture of the distal end side link hub (13) is provided to each of two or more link mechanisms (14). The link actuating device (1) includes a storage unit (8) configured to store therein an operating position of the posture control drive source (11) when the distal end side link hub (13) is in a defined posture. In each of the two or more link mechanisms (14), a positioning portion (4) is provided to at least one of the proximal side end link member (15), the distal side end link member (16), and the intermediate link member (17). A positioning member (3) configured to position the distal end side link hub (13) in the defined posture is dismountably mounted between a plurality of the positioning portions (4).