Dual Leaf-Spring Prosthetic Foot for Adaptive Gait Energy Return
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Solution Overview
Problem
Prosthetic feet often lack versatility, as they are either too stiff for athletic use or too soft for everyday activities, and current designs fail to efficiently store and return sufficient energy to propel the user, limiting their universal applicability.
Innovation Solution
A prosthetic foot design featuring a pair of elongated forefoot leaf springs with different lengths, oriented one over the other, and coupled at both ends with hinge connections, providing a non-linear force deflection under loading during gait, allowing for energy storage and return.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a single spring with fixed stiffness is used in prosthetic feet, then the foot can provide consistent structural support, but it cannot adapt to different activity levels (walking vs. running) and terrain conditions
Solution Approach 1:
The prosthetic foot is divided into multiple leaf springs with different stiffness characteristics arranged in series. Each leaf spring segment has progressively increasing stiffness from bottom to top, allowing the system to provide different levels of support depending on the loading conditions and activity level.
Solution Approach 2:
The prosthetic foot uses a composite structure of multiple leaf springs made from materials with different mechanical properties. The combination of materials and structures creates a progressive stiffness system that adapts to varying loads while maintaining overall structural integrity.
2Adaptability or versatility
If multiple leaf springs with different stiffness are used, then the prosthetic foot can adapt to different activity levels, but the structural complexity increases
Solution Approach 1:
Multiple leaf springs with different stiffness characteristics are combined into a single integrated assembly that functions as one unified prosthetic foot component. The leaf springs are stacked and connected to work together, providing adaptive stiffness without requiring separate interchangeable components.
Solution Approach 2:
The multi-leaf spring assembly serves multiple functions simultaneously: it provides structural support, adapts to different activity levels (walking, running, jumping), and handles various terrain conditions, all within a single integrated component design.
3Strength
If a stiff spring is used for athletic use, then the foot provides necessary strength and support, but it feels too hard for everyday walking activities
Solution Approach 1:
Different regions of the prosthetic foot structure have different stiffness properties. The lower leaf springs are more compliant for comfort during walking, while the upper leaf springs provide increased stiffness and strength for athletic activities, creating a gradient of mechanical properties throughout the structure.
4Ease of operation
If a loose spring is used for everyday use, then the foot feels soft and comfortable, but it is too fragile for athletic activities
Solution Approach 1:
The effective stiffness parameter of the prosthetic foot changes dynamically based on the applied load. During light activities like walking, the system exhibits lower stiffness for comfort. During heavy activities like running or jumping, the progressive engagement of stiffer leaf springs increases the overall stiffness and strength to handle the higher forces.
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 design enhances energy storage and return, enabling the prosthetic foot to respond with a stiffer feel during high loads, such as running, and a looser feel during lower loads, like walking, thereby improving versatility and propulsion.
Implementation Method 1
Each of the pair of forefoot leaf springs has a different length and is coupled to one another at the proximal and distal ends defining an open, uninterrupted gap between the forefoot leaf springs. The pair of forefoot leaf springs together has a non-linear force deflection under loading during gait.
Data Source
AI summary
A prosthetic foot includes a pair of elongated forefoot leaf springs with proximal ends coupled to an attachment member and extending in an arc to distal ends with the forefoot leaf springs being oriented with one over another. The pair of forefoot leaf springs has different lengths and is coupled to one another at the proximal and distal ends defining an open, uninterrupted gap between the forefoot leaf springs. A pair of hinge connections can be disposed each at a different one of the proximal and distal ends of the pair of elongated forefoot leaf springs. The pair of forefoot leaf springs together has a non-linear force deflection under loading during gait.