Inductive Sensor for Prosthetic Joint Angle Measurement
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Solution Overview
Problem
Modern computer-controlled prosthetic devices face limitations due to the sensitivity of electrical sensors to environmental elements and high power consumption, which affects their lifespan and usability in various activities, particularly for amputees of shorter stature or children, as increased battery size and weight become cumbersome.
Innovation Solution
A sensor device utilizing an inductive proximity sensor with a non-ferrous metal material, which detects the amount of metal in proximity to determine the angle of a rotatable member in a prosthetic joint, offering resistance to environmental elements and reduced power draw by employing an absolute or relative monotonic function without the need for memory to calculate positions, thus reducing component count and power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional electrical sensors are used to measure joint angle, then measurement capability is provided, but the sensor lifespan is reduced due to sensitivity to dust, moisture, and environmental elements
Solution Approach 1:
The patent replaces traditional electrical sensors with an inductive sensor system that uses magnetic fields instead of electrical contacts. The inductive sensor detects the position of a magnetic indicator on the rotatable member through magnetic field coupling, eliminating the need for electrical contacts that would be exposed to environmental elements. This substitution of electrical measurement with magnetic field-based measurement resolves the contradiction by maintaining measurement capability while eliminating sensitivity to dust, moisture, and other environmental factors.
2Measurement precision
If the number of electrical parts is increased to provide comprehensive sensor functionality, then measurement capability is improved, but power consumption increases
Solution Approach 1:
The patent extracts and eliminates unnecessary electrical components from the sensor system. By using an inductive sensor that detects position through magnetic field coupling rather than requiring multiple electrical contacts and signal processing circuits, the system achieves comprehensive measurement capability with fewer electrical parts. The inductive sensor directly provides the angle measurement signal without requiring additional electrical components, thereby reducing overall power consumption while maintaining measurement precision.
3Power
If battery size is increased to support higher power draw from multiple electrical parts, then power supply capability is improved, but device size and weight increase
Solution Approach 1:
The patent changes the power consumption parameter of the sensor system by switching from electrical contact-based sensing to inductive sensing. This parameter change reduces the power draw from the battery, which in turn allows for a smaller battery size. The reduced battery size directly decreases the weight of the prosthetic device, resolving the contradiction between power supply capability and device weight.
4Ease of operation
If electrical parts are used for joint angle measurement, then measurement functionality is provided, but device complexity increases
Solution Approach 1:
The patent applies multi-functionality by using a single inductive sensor to perform the joint angle measurement function that would traditionally require multiple electrical parts and signal processing stages. The inductive sensor directly detects the position of the magnetic indicator and provides the angle measurement signal in a single component, eliminating the need for separate electrical contacts, signal conditioners, and processors. This universal approach maintains measurement functionality while significantly reducing device 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 solution enhances the longevity of the sensor and reduces the weight and size of the prosthetic device, allowing amputees to engage in diverse activities while minimizing battery size and weight, thereby improving mobility and usability across different populations.
Implementation Method 1
an inductive proximity sensor configured to detect an amount of metal material in a proximate location to the inductive sensor
Data Source
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AI summary
The present invention relates to a sensor device for determining an absolute angle of a prosthetic joint, and which is resistant to environmental elements and has a reduced power draw. The sensor device includes an inductive sensor and a rotatable member including a metal material. The metal material can include a non-ferrous metal material. The inductive sensor detects an amount of the metal material in a proximate location to the inductive sensor. Rotation of the rotatable member increases or decreases an amount of metal material in the proximate location of the inductive sensor. The amount of metal material in the proximate location corresponds to an angle of the rotatable member and the prosthetic joint based on a monotonic function. Thus, the inductive sensor detects the amount of metal material in the proximate location to determine the angle of the rotatable member and subsequently the angle of the prosthetic device.