Inductive Position Sensing via Modulated Mutual Inductance
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Solution Overview
Problem
Existing position sensing technologies are often expensive, sensitive to contamination, require electrical connections that can lead to mechanical failure, and are affected by temperature drift, particularly in angular position sensing applications.
Innovation Solution
An inductive position sensing system that uses a movable inductive position element with a position inductor and a plurality of inductive load elements, where the load elements are selectively controlled by modulation signals to provide mutual inductance, allowing for the calculation of the position based on changes in the position signal, eliminating the need for conductive connections and reducing sensitivity to environmental factors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If optical encoders are used for position sensing, then measurement precision is improved, but sensitivity to contamination increases
Solution Approach 1:
The patent replaces optical sensing mechanisms with inductive sensing mechanisms. Instead of using optical encoders that require light paths susceptible to contamination, the invention uses inductive position elements and load elements that generate magnetic fields for position detection, eliminating the harmful effect of contamination on measurement precision
Solution Approach 2:
The patent changes the physical parameter used for sensing from optical properties to electrical inductance properties. By measuring changes in inductance of the position element relative to fixed load elements, the system achieves contamination-resistant position sensing while maintaining measurement precision
2Ease of operation
If Hall sensors with permanent magnets are used for position sensing, then ease of operation is improved, but temperature drift increases
Solution Approach 1:
The patent substitutes Hall effect sensors and permanent magnets with an inductive sensing system using inductive position elements and load elements. This replacement eliminates the temperature-sensitive permanent magnets while maintaining ease of operation through non-contact inductive coupling for position detection
Solution Approach 2:
The patent introduces an inductive position element as an intermediary between the actuator and the sensing system. This inductive element mediates the position information through magnetic coupling without requiring direct electrical connections or temperature-sensitive components, thereby reducing temperature drift while preserving operational simplicity
3Measurement precision
If electrical connections are used between moving and non-moving parts for position sensing, then measurement precision is improved, but reliability worsens due to mechanical failure
Solution Approach 1:
The patent replaces electrical connections with inductive coupling between the inductive position element and fixed load elements. This substitution eliminates physical contacts that are susceptible to mechanical failure while maintaining measurement precision through non-contact inductive sensing of position
Solution Approach 2:
The inductive position element serves as an intermediary that transfers position information through magnetic fields without requiring direct electrical or mechanical connections between moving and stationary parts, thereby improving reliability while preserving measurement accuracy
4Measurement precision
If complex circuitry is used for position sensing, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The patent extracts the sensing function from complex circuitry and concentrates it in simple inductive elements. The position element and load elements are designed as simple inductive components without complex internal circuitry, achieving measurement precision through their inductive coupling characteristics rather than complex electronic circuits
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 system provides accurate and reliable angular position sensing without the need for complex circuitry or electrical connections, is resistant to contamination and temperature drift, and offers a cost-effective solution for position sensing applications.
Implementation Method 1
Each of the plurality of inductive load elements can be selectively controlled in response to a modulation signal to provide a corresponding mutual inductance between the position inductor and the respective load inductor, the corresponding mutual inductance depending on a position of the inductive position element relative to the respective load inductor
Data Source
AI summary
One example includes a position sensing system. The system includes an inductive position element that is moveable and comprises a position inductor. The system also includes a plurality of inductive load elements. Each of the inductive load elements includes a load inductor. Each of the plurality of inductive load elements can be selectively controlled in response to a modulation signal to provide a corresponding mutual inductance between the position inductor and the respective load inductor, the corresponding mutual inductance depending on a position of the inductive position element relative to the respective load inductor. The system further includes a position controller configured to generate the position and modulation signals and to calculate the position of the inductive position element relative to the plurality of inductive load elements based on a difference of the position signal with respect to the mutual inductance between the position inductor and each respective load inductor.