Jointless Prosthetic Foot With Convex Attachment Path

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Solution Overview

Problem

Conventional sports prosthetic feet experience misalignment of the action line with the body's center of gravity due to the upward and forward movement of the leaf spring during loading, leading to inefficient energy release and potential slowing of the user.

Innovation Solution

A jointless prosthetic foot with a leaf spring featuring an adjustable attachment adapter that moves along a convex path, maintaining the foot-strike area's position relative to the perpendicular, allowing for variable force introduction without changing the prosthetic setup, and incorporating a concave connecting section to prevent rearward ground contact and maintain constant prosthetic foot height.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If the attachment adapter is fixed on the leaf spring, then the structure is simple, but the adaptability to different user needs is limited

Engineering Contradiction:

Improveadaptability to different user needsVSAvoidstructure complexity

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The attachment adapter is made adjustable along the convex path instead of being fixed, allowing dynamic repositioning to adapt to different user needs while maintaining a relatively simple overall structure

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The prosthetic foot is divided into functional sections (distal foot-strike section, connecting section, proximal attachment section), with the attachment adapter as a separate adjustable component, enabling independent optimization of each section

Inventive Principle:

Principle #1Segmentation

2Adaptability or versatility

If the attachment adapter position is changed in the anterior-posterior direction, then the force lever variability increases, but the foot-strike area position shifts forward causing slowing effect

Engineering Contradiction:

Improveforce lever variabilityVSAvoiduser speed

Core Design Contradiction:

Adaptability or versatilityVSSpeed

Solution Approach 1:

The attachment adapter moves along a convex (curved) path instead of a straight line, which geometrically constrains the motion to maintain constant horizontal distance between the foot-strike area and the perpendicular, preventing forward shifting while allowing force lever adjustment

Inventive Principle:

Principle #14Spheroidality (Curvature)

Solution Approach 2:

The adjustment mechanism transitions from one-dimensional linear movement to two-dimensional curved path movement, adding a vertical dimension to the adjustment while constraining the horizontal position

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

3Use of energy by moving object

If the leaf spring flexes upward and forward during loading, then the spring stores and releases energy, but the action line misaligns with the body's center of gravity reducing efficiency

Engineering Contradiction:

Improveenergy storage and releaseVSAvoidenergy transfer efficiency

Core Design Contradiction:

Use of energy by moving objectVSProductivity

Solution Approach 1:

The convex path geometry ensures that during leaf spring flexion, the attachment adapter's horizontal position relative to the foot-strike area remains constant, keeping the action line aligned with the body's center of gravity and maintaining efficient energy transfer

Inventive Principle:

Principle #14Spheroidality (Curvature)

4Adaptability or versatility

If the attachment adapter is adjustable, then the adaptability increases, but the prosthetic foot height may change affecting user perception

Engineering Contradiction:

ImproveadjustabilityVSAvoidprosthetic foot height

Core Design Contradiction:

Adaptability or versatilityVSShape

Solution Approach 1:

The convex path is designed with specific curvature characteristics that compensate for height changes during adjustment, maintaining substantially constant prosthetic foot height despite the adjustable attachment adapter position

Inventive Principle:

Principle #14Spheroidality (Curvature)

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

This design ensures efficient energy transfer and maintains a constant prosthetic foot height and position of the foot-strike area, enhancing the user's performance by preventing rearward force components and maintaining the prosthetic's dimensions, thus avoiding slowing effects.

Implementation Method 1

The binding to a socket, which is also intended to be possible in below-knee prostheses, has the effect that, during loading, the tip of the leaf spring not only moves upward with respect to the socket, i.e. in the vertical direction, but also moves forward as a result of a flexion of the spring. Moreover, when the energy stored in the spring is released...

Methodology Applied

Scientific EffectElasticity: Elasticity

Data Source

PatentUS10646357B2Jointless prosthetic foot

Publication Date: 2020.05.12 OTTOBOCK SE & CO KGAA

AI summary

A jointless prosthetic foot having a leaf spring which has a distal footfall section, a connecting section and a proximal attachment section which extends in an anterior-posterior direction and to which an attachment adapter can be fixed. The attachment adapter is mounted such as to be movable along a convexly curved path in the anterior-posterior direction.