2-DOF Link Assembly for Compact Joint Motion Assistance
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Solution Overview
Problem
Existing link assemblies and motion assistance apparatuses lack a compact and efficient mechanism to transmit power with 2-degree of freedom rotation, which limits their range of motion and effectiveness in assisting joints like the talocrural, knee, hip, wrist, or elbow joints, especially for elderly or disabled individuals.
Innovation Solution
A link assembly comprising a main frame, base link, input link, and output link with a center of rotation inside the main frame, allowing 2-degree of freedom rotation, supported by a rotary frame and connected through ball joints and universal joints, enabling a compact structure with enhanced range of motion and power transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a traditional link assembly structure is used, then the structure is simple, but the range of motion is limited and cannot achieve 2-degree of freedom rotation
Solution Approach 1:
The output link is nested within the main frame with its center of rotation positioned inside the main frame body. The rotary frame is rotatably connected to the interior of the main frame and supports the output link, creating a compact nested configuration that enables 2-DOF rotation without increasing external dimensions or structural complexity
Solution Approach 2:
The patent introduces rotational motion in multiple dimensions by enabling the output link to perform 2-degree of freedom rotation. The axis of rotation of the main frame with respect to both the base link and input link passes through the center of rotation of the output link, creating multi-dimensional motion capability while maintaining a compact three-dimensional structure
2Volume of moving object
If the center of rotation of the output link is outside the main frame, then the output link has easier access to external connections, but the structure becomes less compact and more prone to friction
Solution Approach 1:
The output link's center of rotation is positioned inside the main frame, and the output head is connected to the interior of the main frame in a ball joint manner. This nested configuration maximizes compactness while the ball joint provides omnidirectional connection capability, effectively resolving the conflict between compactness and connection accessibility
3Reliability
If conventional joints are used, then the mechanism is easier to manufacture, but friction is higher and stability is reduced
Solution Approach 1:
The patent employs ball joints for connecting the output head to the main frame and the input head to the base head. These spherical joints provide smooth rotational motion with reduced friction compared to conventional hinge joints, enhancing stability and reliability while remaining manufacturable using standard machining processes
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 solution provides a compact and efficient power transmission mechanism that extends the range of motion, allowing for effective assistance of joints like the talocrural joint, enhancing mobility and support for users by enabling both rotational and translational motions with reduced friction and increased stability.
Implementation Method 1
an output head connected to an interior of the main frame in a ball joint manner
Implementation Method 2
enabling both rotational and translational motions with reduced friction and increased stability
Data Source
AI summary
A link assembly includes a main frame, a base link rotatably connected to the main frame, an input link rotatably connected to the main frame, and an output link at least 2-degree of freedom (DOF) rotatably connected to the main frame.