Angular Position Sensor with Segmented Magnet for Linear Output
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Solution Overview
Problem
Existing angular position sensors face challenges in measuring magnetic flux density with high linearity, leading to increased operational load due to the need for complex trigonometric calculations and mapping, especially when determining the absolute angular position of a rotary shaft.
Innovation Solution
An angular position sensor design featuring a hard magnetic member with uniform magnetic flux distribution and a soft magnetic member forming a magnetic circuit, along with a magnetic flux density measuring sensor, which produces a signal indicative of the angular position, allowing for linear output changes upon rotation. This design includes a hard magnetic member with varying thickness and sub-soft magnetic members to maintain flux uniformity and minimize external interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a ring-shaped magnet with N-pole and S-pole arrayed in circumferential direction is used, then the magnetic flux density can be measured, but the output changes in sine wave form which reduces measurement linearity
Solution Approach 1:
The magnet is divided into multiple independent magnetic segments (first magnetic segment, second magnetic segment, etc.) along the circumferential direction. Each segment can be independently designed with specific magnetic properties and pole configurations. This allows different regions of the magnet to produce different magnetic flux density characteristics, enabling linear output while maintaining measurement capability.
Solution Approach 2:
The ring-shaped magnet is segmented into multiple independent magnetic segments arranged in circumferential direction. Each segment acts as an independent magnetic unit that can be optimized separately. This segmentation enables the overall system to achieve linear output by carefully designing the magnetic properties of individual segments.
2Measurement precision
If traditional magnetic sensor structure is used, then angular position can be detected, but complex trigonometric calculations are required increasing operational load
Solution Approach 1:
The magnetic flux density distribution is changed by adjusting the magnetic segment configurations, pole pairs, and spacing parameters. By optimizing these parameters, the output of the magnetic sensors becomes proportional to the angular position, transforming the relationship from trigonometric to linear, thereby reducing calculation complexity.
3Ease of operation
If uniform magnetic flux distribution is achieved, then linear output is improved, but magnetic circuit design becomes more complex
Solution Approach 1:
Different magnetic segments are designed with different local magnetic properties, pole configurations, and flux densities according to the specific requirements of each region. This localized optimization allows uniform overall flux distribution while keeping individual segment designs manageable and systematic.
Solution Approach 2:
The magnetic circuit is divided into multiple independent segments that can be designed and optimized separately. This segmentation simplifies the overall design process by breaking down the complex uniform flux distribution problem into smaller, more manageable sub-problems for each magnetic segment.
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 provides a more linear output change with reduced operational load, enabling accurate angular position determination through simpler calculations and minimizing errors from external magnetic disturbances.
Implementation Method 1
a hard magnetic member connected to a rotary member, the hard magnetic member having a circumference and magnetized in a circumferential direction thereof to produce a magnetic field therearound
Implementation Method 2
a soft magnetic member disposed within the magnetic field produced by the hard magnetic member to form a magnetic circuit
Implementation Method 3
a magnetic flux density measuring sensor disposed at an interval away from the soft magnetic member. The magnetic flux density measuring sensor works to measure the magnetic flux density in the magnetic circuit to produce a signal as a function of the magnetic flux density
Data Source
AI summary
An angular position sensor is provided which is designed to an angular position of a rotary shaft. The angular position sensor has a magnet affixed to the rotary shaft. The magnet has an N-pole and an S-pole and is so geometrically shaped as to produce magnetic flux which is substantially uniform in amount within a range extending around each of centers of the N-pole and the S-pole. This improves the linearity of a change in sensor output upon rotation of the rotary shaft.