Variable Friction Shoe for Foot Drop Rehabilitation
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Solution Overview
Problem
Current rehabilitation devices for foot drop, such as the MIT-Skywalker, face challenges with high cost, complexity, and portability, limiting their effectiveness for regular, independent use outside clinical settings.
Innovation Solution
A variable friction shoe with a midsole and outsole that features a high-friction surface during the stance phase and a low-friction surface during the swing phase, utilizing compressible materials and low-friction materials like PTFE to adapt to changing ground reaction forces, allowing for improved gait mechanics and reduced slipping.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If robotic rehabilitation devices like MIT-Skywalker are used to restore rhythmic gait, then gait rhythmicity is improved, but cost and device complexity increase significantly
Solution Approach 1:
The patent changes the friction parameter of the shoe-outsole interface dynamically during the gait cycle. By varying friction levels between swing and stance phases, the system restores gait rhythmicity without requiring complex robotic actuation mechanisms, thereby resolving the contradiction between reliability improvement and device complexity avoidance
Solution Approach 2:
The patent introduces dynamic friction modulation through materials that automatically adjust their friction characteristics based on loading conditions. This dynamic behavior enables gait restoration while maintaining a simple, passive device structure, addressing both improved reliability and reduced complexity
2Speed
If robotic rehabilitation devices are used for foot drop, then swing phase clearance is improved, but portability deteriorates
Solution Approach 1:
The patent modifies the friction parameter of the outsole to enable rapid swing phase clearance. By using materials that provide low friction during swing, the device achieves improved foot clearance without the portability penalties associated with heavy robotic actuators
Solution Approach 2:
The friction-modulating materials automatically adjust their properties based on the gait phase and loading conditions without requiring external control systems. This self-regulating behavior enables effective swing clearance while maintaining device portability and simplicity
3Reliability
If static ankle-foot orthosis is used for foot drop, then ankle dorsiflexion is supported, but gait naturalness and efficiency are reduced
Solution Approach 1:
The patent transitions from static to dynamic friction characteristics in the shoe-outsole system. The friction level automatically adapts during the gait cycle, providing support when needed while minimizing interference during swing, thereby improving both reliability and gait efficiency
Solution Approach 2:
By changing the friction parameter dynamically rather than maintaining a fixed mechanical constraint, the device provides necessary dorsiflexion support while allowing more natural and efficient gait mechanics compared to static orthotic approaches
4Stability of the object's composition
If high-friction outsole is used throughout gait cycle, then stance phase stability is improved, but swing phase performance deteriorates due to increased friction
Solution Approach 1:
The patent applies periodic variation in friction characteristics that corresponds to the gait cycle. Low friction is provided during swing phase to enhance performance, while high friction is provided during stance phase to ensure stability, resolving the contradiction between these two opposing requirements
Solution Approach 2:
The friction parameter is dynamically adjusted based on gait phase: reduced during swing to improve speed and reduced during stance to maintain stability. This parameter modulation resolves the contradiction between swing performance and stance stability
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 variable friction shoe enhances walking speed, reduces hip angle compensation, and improves gait efficiency for individuals with foot drop by providing adaptive friction levels, making it a more practical and cost-effective solution for daily use.
Implementation Method 1
the compressible material is compressed, which causes the low-friction surface to recede from a position prominent relative to the high-friction surface
Implementation Method 2
During the swing stage of the gait, when vertical GRFs are low, the low-friction surface allows the shoe to slide along the ground
Data Source
AI summary
A variable friction shoe includes a midsole and an outsole. The outsole includes at least a first high-friction surface and at least a first low-friction surface, wherein the first low-friction surface remains prominent if vertical ground reaction forces (GRFs) are low and wherein the high-friction surface is prominent in response to increasing GRFs.