Adjustable Prosthetic Blade Connector for Variable Torsional Stiffness
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Solution Overview
Problem
Existing prosthetic implants struggle to accurately mimic the natural gait cycle of amputees, particularly in terms of varying torsional stiffness and adapting to different ground conditions and loads, leading to discomfort and fatigue.
Innovation Solution
A prosthetic implant with laminated composite blades and an articulated joint, featuring a connector with adjustable length and position to vary torsional stiffness non-linearly, replicating the force-deformation curve of a natural foot.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a prosthetic implant uses a fixed stiffness design, then the structure is simple and reliable, but it cannot adapt to different ground conditions and loads, reducing comfort and increasing fatigue
Solution Approach 1:
The patent applies the dynamics principle by implementing a variable stiffness mechanism that allows the prosthetic implant to dynamically adjust its mechanical properties. The connector can be moved between different positions (first position for higher stiffness, second position for lower stiffness) to adapt to varying ground conditions and loads during the gait cycle, transforming a static structure into a dynamic one that responds to operational requirements
Solution Approach 2:
The patent applies the parameter changes principle by modifying the stiffness parameter of the prosthetic implant through positional adjustment of the connector. By changing the connector's position along the blade, the system alters the effective stiffness of the foot element, enabling adaptation to different terrain and load conditions without requiring completely different structural designs
2Adaptability or versatility
If the prosthetic implant allows varying stiffness, then it adapts better to patient needs, but the mechanism to connect/disconnect components becomes complex and difficult to actuate
Solution Approach 1:
The patent applies the partial action principle by providing multiple intermediate positions for the connector between the extreme first and second positions. This allows the system to achieve variable stiffness through partial adjustments rather than requiring complete disconnection or reconnection of components, simplifying the actuation process while maintaining adaptability
Solution Approach 2:
The patent applies the mechanics substitution principle by replacing complex mechanical connection/disconnection mechanisms with a sliding or movable connector system. Instead of requiring intricate coupling and uncoupling operations, the connector can be moved along the blade to different positions, achieving variable stiffness through a simpler mechanical action that is easier to actuate
3Reliability
If the prosthetic implant uses linear spring stiffness, then the structure is simple, but it cannot precisely mimic the non-linear force-deformation curve of natural gait
Solution Approach 1:
The patent applies the parameter changes principle by utilizing the non-linear elastic properties of composite materials for the blade construction. The laminate composite structure exhibits non-linear stress-strain behavior that naturally mimics the force-deformation characteristics of natural foot tissue during the gait cycle, eliminating the need for complex active control systems to achieve physiological accuracy
Solution Approach 2:
The patent applies the composite materials principle by constructing the blade from laminate composite materials that possess inherent non-linear elastic properties. These composite structures can be designed to exhibit specific force-deformation curves that replicate natural gait mechanics, providing biologically accurate performance through material selection rather than mechanical complexity
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 prosthetic implant provides a comfortable and reliable simulation of natural foot function, adapting to different loads and ground conditions by varying torsional stiffness in a non-linear manner, enhancing user mobility and reducing fatigue.
Implementation Method 1
laminated composite blades...capable of replicating, in a substantially faithful manner, the force-deformation curve representing the behaviour of a foot of a non-amputee patient
Implementation Method 2
prosthetic implant of the ESR (energy-storing-and-returning) type
Implementation Method 3
The connector is located in the rear region of the foot and has a first end that is connected to the upper assembly and a second end that is connected to the intermediate blade...one between the first and the second end of the connector is movable along a movement direction to vary the force applied on the intermediate blade
Implementation Method 4
varying the torsional stiffness of the ankle portion of the implant...controlling the torsional stiffness of the articulated system
Data Source
Figure 1
Figure 1A~2A
Figure 2B~2C
AI summary
A prosthetic implant (100) of the ESR (energy-storing-and-returning) type, comprises an upper assembly (200) and a lower assembly (300), configured to define a foot and including a lower blade (400b), an intermediate blade (400b) and an upper blade (400c). The upper blade (400c), the lower blade (400a) and the intermediate blade (300c) are fastened stably to each other at at least one connecting point (C) located in the front region (300a) or in the middle region (300b) of the foot. An articulated joint (5009) is interposed between the lower assembly (300) and the upper one (200) to allow relative motion between them. The implant comprises a connector (600) having a first end (600a) that is connected to the upper assembly (200) and a second end (600b) that is connected to the intermediate blade (400b) of the lower assembly (300). At least one between the first and the second end (600a, 600b) of the connector (600) is movable along a movement direction (X) to vary the force applied on the intermediate blade (400b) of the lower assembly (300).