Geomagnetic Sensor Control for Prosthetic Gait Stability

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Solution Overview

Problem

Conventional prosthetic and orthotic devices lack the ability to dynamically adjust to changing environments, leading to movement instability, high energy expenditure, and gait deviations due to the absence of effective sensors that can detect sudden changes in direction.

Innovation Solution

Incorporating geo-magnetic sensors to measure orientation and movement with respect to the earth's magnetic field, allowing for real-time feedback control and comparison with predefined safe and unsafe gait patterns to issue warnings or adjust movement accordingly.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If conventional sensors (proximity, load, accelerometers, tactile sensors, pressure sensors) are used in prosthetic or orthotic devices, then basic feedback control is provided, but the system cannot detect sudden changes in direction and identify unsafe gait patterns

Engineering Contradiction:
Improvedirectional detection capabilityVSAvoidinformation about sudden direction changes
Core Design Contradiction:
Measurement precisionVSLoss of information

Solution Approach 1:

The patent replaces conventional mechanical and basic electronic sensors (accelerometers, pressure sensors) with a geomagnetic sensor system that uses the Earth's magnetic field as a reference. This substitution enables precise detection of directional changes and gait patterns by measuring orientation relative to the magnetic north, providing information that mechanical sensors cannot capture.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent introduces the Earth's magnetic field as an intermediary reference frame for directional measurement. By using the geomagnetic field as a stable external reference, the system can accurately determine orientation and detect changes in gait patterns without relying solely on internal sensor measurements, which may drift or lack absolute directional context.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Device complexity

If basic controllers are used to artificially mobilize joints without user interaction, then device complexity is reduced, but movement stability and adaptability to dynamic environments deteriorate

Engineering Contradiction:
Improvecontroller structureVSAvoidmovement stability
Core Design Contradiction:
Device complexityVSReliability

Solution Approach 1:

The patent implements a feedback control system where geomagnetic sensor data continuously monitors user movement and orientation. The controller compares measured gait patterns against stored safe/unsafe patterns and provides real-time feedback by adjusting actuator commands or alerting the user, thereby maintaining movement stability and preventing unsafe motions without requiring complex user interaction.

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The patent transitions from static, pre-programmed joint mobilization to dynamic, adaptive control that responds to real-time geomagnetic sensor measurements. The system dynamically adjusts its control strategy based on detected gait patterns and environmental context, enabling adaptability to changing conditions while maintaining manageable device complexity through pattern recognition algorithms.

Inventive Principle:
Principle #15Dynamics

3Device complexity

If conventional passive prosthetic and orthotic devices are used, then device complexity is minimized, but energy expenditure by the user increases and gait deviations occur

Engineering Contradiction:
Improvedevice structureVSAvoiduser energy expenditure
Core Design Contradiction:
Device complexityVSUse of energy by moving object

Solution Approach 1:

The patent enables the prosthetic or orthotic device to monitor and regulate its own operation through geomagnetic sensing and automated pattern recognition. The system independently detects unsafe gait patterns and adjusts actuator commands or provides alerts without requiring user intervention, allowing the device to serve itself in maintaining safe and efficient movement while reducing user energy expenditure.

Inventive Principle:
Principle #25Self-service

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 geo-magnetic sensing system enhances stability and control by providing immediate directional information, enabling safer and more efficient movement, reducing the risk of injury and improving user training in healthy movement techniques.

Implementation Method 1

measuring with a geo-magnetic sensor a plurality of data points over a time interval. The plurality of data points provides orientation data information of a prosthetic or orthotic device with respect to the earth's magnetic field

Methodology Applied
Scientific EffectGeomagnetic sensing: Magnetic Field

Data Source

PatentEP2434992B1Control systems and methods for prosthetic or orthotic devices
Publication Date: 2019.06.26 OSSUR HF
  • EP2434992B1 patent drawingFigure 1A
  • EP2434992B1 patent drawingFigure 1B
  • EP2434992B1 patent drawingFigure 2A~2B

AI summary

Geomagnetic methods and systems are used for monitoring the directionality of a prosthetic or orthotic device. Certain methods may include measuring multiple data points over a particular time interval to identify orientation information with respect to a prosthetic or orthotic device and/or used in the real-time control of the prosthetic or orthotic device. In certain examples, multiple points may be further compared with stored orientation data associated with predefined unsafe gait patterns. Control instructions and/or alerts based on the geomagnetic measurements can then be generated for the prosthetic or orthotic device, such as if the orientation data information matches one of the predefined unsafe gait patterns.