Variable Stiffness Force Transmitting Frame for Ankle Assistance
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Solution Overview
Problem
Existing force transmitting frames are rigid, limiting the ability to transmit force specifically to certain portions, and ankle motion assistance devices fail to effectively power the forefoot during toe-off motions.
Innovation Solution
A force transmitting frame design with flexible middle portions and stiffer ends, allowing for improved force transmission between ends, and incorporating an actuator and power transmitting cables to assist toe-off motions by powering the forefoot directly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a rigid force transmitting frame is used, then structural strength is maintained, but the ability to transmit force specifically to certain portions is limited
Solution Approach 1:
The force transmitting frame employs different stiffness characteristics in different regions: the end portions are designed with higher stiffness to provide structural strength and force transmission capability, while the middle portion has lower stiffness to allow flexibility and adaptation. This local differentiation of mechanical properties enables the frame to simultaneously maintain overall strength while providing targeted force transmission to specific portions.
Solution Approach 2:
The force transmitting frame is divided into distinct segments with different mechanical properties: first and second end portions with higher stiffness and a middle portion with lower stiffness. This segmentation allows each region to perform its specific function - the end portions transmit force effectively while the middle portion provides flexibility, resolving the contradiction between overall strength and localized force transmission.
2Ease of operation
If existing ankle motion assistance devices are used, then basic support is provided, but effective powering of the forefoot during toe-off motions is not achieved
Solution Approach 1:
The force transmitting frame transitions from a static rigid structure to a dynamic structure with variable stiffness along its length. The middle portion's flexibility allows the frame to adapt its shape during motion, enabling effective force transmission to the forefoot during toe-off motions while maintaining basic support functionality throughout the gait cycle.
Solution Approach 2:
The flexible middle portion acts as an intermediary element that transmits and modulates force between the powered end portions. This intermediate section allows the device to maintain basic support while effectively delivering power to the forefoot during toe-off by adapting its mechanical properties to the specific phase of gait.
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
Enhances muscular strength assistance and improves user mobility by effectively transmitting force to the forefoot, minimizing body strain and enhancing the toe-off motion.
Implementation Method 1
a second longitudinal member with one end sliding with respect to the base
Implementation Method 2
a fastener configured to apply a fastening force to a first end of the first longitudinal member and a first end of the second longitudinal member
Data Source
Figure 1~2
Figure 3A~3C
Figure 4A~5
AI summary
A force transmitting frame including a base, a first longitudinal member connected to the base, a second longitudinal member configured to slide with respect to the base, and a first fastener configured to fasten one end of the first longitudinal member and one end of the second longitudinal member is provided.