Asymmetric Ring Magnet Position Sensing for Full-Revolution Angle Detection
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Solution Overview
Problem
Existing magnetic sensors face challenges in providing unambiguous angular measurements within one full revolution of a rotating object, particularly in applications requiring precise rotational angle or position sensing.
Innovation Solution
An apparatus and method utilizing a ring magnet with asymmetrically magnetized pole pairs, including at least one larger pole pair and multiple smaller pairs, coupled with a sensor to differentiate these signals digitally for precise position determination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a conventional magnetic sensor with uniformly magnetized pole pairs is used, then the sensor can detect rotational position, but it cannot provide unambiguous angular measurements within one full revolution
Solution Approach 1:
The patent applies asymmetry by making at least one pole pair larger than the other pole pairs on the ring magnet. This asymmetric configuration creates a unique magnetic field pattern that allows the sensor to distinguish between different rotational positions within a single revolution, thereby providing unambiguous angular measurements while maintaining continuous rotational position information
Solution Approach 2:
The ring magnet is segmented into multiple pole pairs with different sizes. This segmentation creates distinct magnetic signatures for each pole pair, enabling the sensor to identify specific angular positions. The digital circuit processes these segmented signals to determine precise rotational position within one full revolution
2Measurement precision
If a ring magnet with asymmetric pole pairs is used, then unambiguous angular measurements can be achieved, but the manufacturing complexity increases
Solution Approach 1:
The patent changes the physical parameter of pole pair size to create asymmetric magnetic patterns. By varying the size parameter of different pole pairs rather than changing the fundamental structure or material composition, the design achieves precise angular measurement capability while maintaining compatibility with conventional magnet manufacturing processes
3Measurement precision
If digital signal processing is added to differentiate pole pairs, then precise position determination is achieved, but the device complexity increases
Solution Approach 1:
The patent replaces complex mechanical position encoding mechanisms with a simpler magnetic field pattern approach. The asymmetric pole pairs create inherent magnetic signatures that require only basic digital signal processing to interpret, rather than complex mechanical encoders or multiple sensor arrays, thereby reducing overall device complexity while achieving precise position sensing
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 and repeatable detection of rotational positions, providing identifiable home and stop points for actuation control, enhancing precision in automotive and industrial applications.
Implementation Method 1
a sensor that is sensitive to magnetic polarities... The sensor detects each period of an analog signal produced by the magnetic polarities of each pole pair
Data Source
AI summary
An apparatus and method for determining the position of a ring magnet fixed to a rotating device includes locating the ring magnet proximate to a sensor that is sensitive to magnetic polarities. The ring magnet includes a plurality of magnetic pole pairs of opposite magnetic polarities, having at least one pole pair larger than at least three other pole pairs. The sensor produces an output signal for each pole pair that represents a period when a pole pair is detected by the sensor as the ring magnet is rotated by the device. The output signals from the sensor are coupled to a digital circuit that differentiates the three smaller pole pairs from the at least one larger pole pair to determine the position of the ring magnet.