Inductive Joint Sensor for Torsion and Bending Measurement
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Solution Overview
Problem
Existing methods for measuring torsion and bending in joints, such as those in the human or animal body, face limitations in detecting a wide range of motions due to mechanical fragility and limited angle measurement capabilities, particularly with optical fibers which are prone to damage and restricted to small angles.
Innovation Solution
A sensor system utilizing an electrically conductive loop that extends across both limbs at a joint, allowing for the measurement of self-inductance and mutual inductance to detect a wide range of bending and torsion motions, with the loop being flexible to accommodate large deformations without damage, and optionally calibrated with additional sensors for accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If optical fibers are used for measuring joint angles, then measurement precision is improved, but reliability deteriorates due to mechanical fragility and limited angle range
Solution Approach 1:
The patent replaces the mechanical optical fiber system with an electrical inductance-based sensing system. The conductive loop integrated into the garment uses electromagnetic induction to measure joint angles, eliminating the mechanical fragility of optical fibers while maintaining measurement precision through inductance changes detected by a sensor.
Solution Approach 2:
The patent changes the measurement parameter from optical properties (light transmission) to electrical properties (inductance). By measuring the inductance of a conductive loop that deforms with joint movement, the system achieves both high measurement precision and improved reliability, as electrical conductors are more mechanically robust than optical fibers.
2Adaptability or versatility
If a conductive loop extends across both limbs at a joint, then the measurement range is improved to detect wide range of motions, but the device complexity increases
Solution Approach 1:
The conductive loop integrated into the garment serves multiple functions: it acts as both the sensing element and the structural component of the garment. This single element can detect various types of joint movements (bending, torsion) across different joints, providing universal applicability without requiring separate sensors for each measurement type.
Solution Approach 2:
The patent merges the sensor with the garment structure by integrating the conductive loop directly into the fabric. This combination eliminates the need for separate sensor assemblies and mounting mechanisms, reducing device complexity while maintaining the ability to measure a wide range of motions through the loop's deformation.
3Measurement precision
If additional sensors are added for calibration, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The system performs self-calibration by utilizing the known geometric relationship between the conductive loop and the joint it measures. The loop's inherent deformation characteristics serve as the calibration reference, eliminating the need for external calibration sensors or complex calibration procedures, thus maintaining measurement precision without increasing 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
Enables accurate measurement of torsion and bending across a wide range of angles, including large deformations, with enhanced sensitivity and reliability, suitable for dynamic situations without compromising mechanical integrity.
Implementation Method 1
A sensor system utilizing an electrically conductive loop that extends across both limbs at a joint, allowing for the measurement of self-inductance and mutual inductance to detect a wide range of bending and torsion motions
Implementation Method 2
allowing for the measurement of self-inductance and mutual inductance to detect a wide range of bending and torsion motions
Data Source
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AI summary
Method, device and system for measuring a degree of torsion or bending of a joint. The method comprises the steps of attaching a sensor (56) to the limbs that are joined by the joint, measuring an output signal of the sensor during torsion or bending at the joint, and a final step of relating said output signal of the sensor to a degree of torsion or bending. The sensor comprises an electrically conductive loop (51), with loop parts that run from one limb to other and back in the loop, the area of said loop at least partially covering both limbs from one limb to the other. The limbs may be limbs of the human or animal body, for instance limbs at a knee. The sensor further comprises an output unit (57) for providing an output signal that is a measure for the inductance of the loop. Calibration data for the sensor may be determined by detecting the output signal of the sensor for a well defined degree of torsion or bending at said joint under static conditions and storing the calibration data.