Robotic Prosthetic Leg With Wire-Guided Elastic Torque Assistance

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Solution Overview

Problem

Conventional prosthetic legs struggle to generate sufficient torque while maintaining a lightweight design for natural walking, posing challenges in stability and balance.

Innovation Solution

A robotic prosthetic leg design incorporating an ankle bracket, driving part, guide bracket, wire, pressing part, and elastic members to provide rotational torque and maintain a predetermined angle, utilizing elastic restoring forces for stable movement.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Force

If conventional prosthetic leg design is used, then the structure is simple and weight is reduced, but sufficient torque for natural walking cannot be generated

Engineering Contradiction:
ImprovetorqueVSAvoidstructure complexity
Core Design Contradiction:
ForceVSDevice complexity

Solution Approach 1:

The prosthetic leg is divided into multiple functional modules: driving part with motor, transmission mechanism with wire and pulley, elastic member for energy storage, and control unit. Each module performs a specific function, allowing the system to generate sufficient torque while maintaining manageable complexity through functional segmentation.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The prosthetic leg incorporates dynamic elements including a motor that actively adjusts torque output, an elastic member that dynamically stores and releases energy during the walking cycle, and a control unit that adapts to user movement patterns. This dynamic behavior enables the system to generate required torque on demand rather than requiring constant high-torque mechanical structures.

Inventive Principle:
Principle #15Dynamics

2Force

If high torque is generated for natural walking, then gait momentum is sufficient, but the prosthetic leg weight increases

Engineering Contradiction:
ImprovetorqueVSAvoidprosthetic leg weight
Core Design Contradiction:
ForceVSWeight of moving object

Solution Approach 1:

The elastic member operates in a periodic manner, storing energy during the stance phase when the user's weight compresses it, and releasing this energy during the swing phase to assist with limb advancement. This periodic energy storage and release provides torque augmentation without requiring continuous high-power motor operation, thereby reducing overall system weight.

Inventive Principle:
Principle #19Periodic action

Solution Approach 2:

The control unit dynamically adjusts motor operating parameters including torque output, rotation speed, and activation timing based on the user's walking phase and intensity. This parameter modulation allows the motor to deliver high torque only when necessary, reducing the need for an oversized motor and associated heavy mechanical components.

Inventive Principle:
Principle #35Parameter changes

3Power

If elastic member is compressed during driving part rotation, then additional rotational force is generated, but the wire and guide conduit structure becomes more complex

Engineering Contradiction:
Improverotational forceVSAvoidwire and guide conduit structure
Core Design Contradiction:
PowerVSDevice complexity

Solution Approach 1:

The guide conduit acts as an intermediary structure that channels the wire between the driving part and the elastic member. This intermediary component simplifies the overall wire routing by providing a dedicated pathway, reducing the complexity of managing wire tension and movement while enabling the elastic member to effectively transmit force to the driving part.

Inventive Principle:
Principle #24Intermediary (Mediator)

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 enables stable and efficient walking by generating additional rotational force through elastic members, reducing load on the driving part and maintaining uniform angles during toe-off and ground contact.

Implementation Method 1

a first elastic member 600 disposed between the base block 310 and the pressing part 500 to enclose the guide conduit 330, and configured to support the pressing part 500 toward the front side of the treading member 10

Methodology Applied
Scientific EffectElasticity: Elasticity

Implementation Method 2

The wire 400 has a rear side connected to the driving part 200 and extends toward a front side of the treading member 10 with enclosing a lower side of the driving part 200

Methodology Applied
Scientific EffectTension: Tension

Implementation Method 3

The wire 400 extends through the guide conduit 330

Methodology Applied
Scientific EffectFriction: Friction

Data Source

PatentEP3922216B1Robotic prosthetic leg and method for driving robotic prosthetic leg
Publication Date: 2025.09.17 KOREA INST OF MACHINERY & MATERIALS
  • EP3922216B1 patent drawingFigure 1
  • EP3922216B1 patent drawingFigure 2
  • EP3922216B1 patent drawingFigure 3A~3B

AI summary

In a robotic prosthetic leg and a method for driving the robotic prosthetic leg, the robotic prosthetic leg includes an ankle bracket, a driving part, a guide bracket, a wire, a pressing part and a first elastic member. The ankle bracket is disposed at a rear upper side of a treading member. The driving part is rotatably combined with the ankle bracket. The guide bracket has a base block and a guide conduit. The wire has a rear side connected to the driving part and extending toward a front side of the treading member. The pressing part is combined with a front side of the wire. The first elastic member is disposed between the base block and the pressing part to enclose the guide conduit and is configured to support the pressing part.