Inductive Angle Sensor Using Coprime Symmetry Coils
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Solution Overview
Problem
Inductive angle sensors face challenges with limited resolution, ambiguity in angular displacement measurement, and susceptibility to external magnetic fields due to their design, which affects their precision and reliability.
Innovation Solution
The design incorporates a stator with m-fold and n-fold symmetry pickup coil arrangements and conductive targets, where m and n are coprime, allowing for independent signal processing of induced signals to determine rotational position with enhanced resolution and robustness against external interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a single pickup coil arrangement with m-fold symmetry is used, then the device complexity is reduced, but the measurement precision and resolution are limited due to ambiguity over full revolution
Solution Approach 1:
The pickup coil arrangement is segmented into multiple independent coil sets, each with different fold symmetries (m-fold and n-fold where gcd(m,n)=1). Each coil set independently measures angular displacement within its periodic range, and the results are combined to achieve unambiguous measurement over full revolution, resolving the measurement precision limitation without requiring a single complex coil arrangement.
Solution Approach 2:
The solution transitions from a single-dimensional measurement (one pickup coil arrangement with limited periodicity) to a multi-dimensional measurement system. By using multiple pickup coil arrangements with different fold symmetries, the system creates independent measurement dimensions that, when combined, eliminate ambiguity and extend the measurable range to full revolution.
2Reliability
If conventional inductive angle sensor design is used, then the device structure is simple, but the reliability is reduced due to susceptibility to external magnetic fields
Solution Approach 1:
Astatic targets are introduced as intermediary elements between the exciter coil and pickup coils. These astatic targets generate magnetic flux that is insensitive to external magnetic field interference, acting as a mediator that transfers rotational position information while filtering out external magnetic disturbances, thereby improving reliability without fundamentally changing the inductive sensing principle.
3Measurement precision
If pickup coil arrangements with different fold symmetries are used, then the measurement precision and unambiguity are improved, but the device complexity increases due to multiple coil arrangements and signal processing requirements
Solution Approach 1:
The signal processing is segmented into independent processing channels for each pickup coil arrangement. Each channel processes signals from its corresponding coil set independently, determining angular displacement within its own periodic range. This segmentation simplifies the overall processing complexity by avoiding the need for complex integrated processing of all signals simultaneously, while still achieving high precision through combination of results.
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
This approach provides unambiguous angular displacement measurement over a full revolution, improving resolution and robustness against external magnetic fields, enabling precise determination of rotational position.
Implementation Method 1
the determination of the relative displacement is based on the principle of electrical induction. the stator generates an alternating magnetic field. The rotor may comprise a target coil, wherein the alternating magnetic field induces eddy currents in the target coil
Implementation Method 2
the alternating magnetic field induces eddy currents in the target coil which results in a magnetic flux. The aforementioned magnetic flux induces an induction current in the pickup coil
Data Source
AI summary
An inductive angle sensor for determining a rotational position of a rotor relative to a stator includes an exciter coil, at least one pickup coil arrangement having an m-fold symmetry and at least one conductive target having an m-fold symmetry. The exciter coil may excite the conductive target which, in turn, may induce an induced signal in the pickup coil arrangement. A signal analysis device may determine the rotational position of the rotor based on the induced signal. The inductive angle sensor may comprise a second pickup coil arrangement having an n-fold symmetry and a second conductive target having an n-fold symmetry. The exciter coil may excite the second conductive target which, in turn, may induce a second induced signal in the second pickup coil arrangement. The signal analysis device may determine the rotational position of the rotor based on the two induced signals according to a Vernier principle.