Relative Angle Detection Device Using Magnetic Field Correction
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Solution Overview
Problem
Existing rotation angle detection devices face challenges in accurately sensing relative rotation angles between coaxially arranged rotary shafts, especially when the magnitudes of magnetic field components orthogonal to each other in the magnetically sensitive surface are different.
Innovation Solution
A relative angle detection device is proposed, comprising a magnet on one rotary shaft, two magnetic field sensing units on the other shaft, a correction unit to adjust output values based on the amplitude ratio of magnetic field components, and a computing unit to calculate the relative angle, allowing for accurate detection even with differing magnetic field component amplitudes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a magnet and magnetic field sensing unit are used to detect relative rotation angle between two coaxially arranged rotary shafts, then the device can detect rotation angles, but sensing accuracy deteriorates when the magnitudes of magnetic field components orthogonal to each other in the magnetically sensitive surface are different
Solution Approach 1:
The patent applies parameter changes by detecting the amplitude ratio of orthogonal magnetic field components and using this ratio to determine correction values. The correction unit modifies the output values of magnetic field sensing units based on the detected amplitude ratio, thereby compensating for non-ideal magnetic field conditions and maintaining accurate rotation angle detection
Solution Approach 2:
The patent implements feedback by using the detected amplitude ratio of magnetic field components to dynamically determine correction values. The correction unit continuously adjusts output values based on the measured magnetic field characteristics, creating a closed-loop system that maintains sensing accuracy despite variations in magnetic field amplitude
2Measurement precision
If correction values are applied based on amplitude ratio of magnetic field components, then sensing accuracy is improved, but device complexity increases due to additional correction and computation units
Solution Approach 1:
The patent applies universality by designing correction values and correction methods that can be applied across different device configurations and magnetic field conditions. The correction unit and computing unit serve multiple functions: detecting amplitude ratios, determining correction values, correcting output values, and computing rotation angles, thereby managing complexity through multi-functional integration
3Measurement precision
If the device layout is fixed to ensure equal magnetic field component amplitudes, then sensing accuracy is maintained, but manufacturing flexibility and ease of assembly are reduced
Solution Approach 1:
The patent applies self-service by enabling the device to automatically detect and compensate for its own magnetic field characteristics. The magnetic field sensing units detect the amplitude ratio of orthogonal components, and the correction unit automatically applies appropriate correction values, allowing the device to maintain accuracy without requiring precise manual alignment or fixed layout during manufacturing and assembly
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 solution enables high-accuracy sensing of rotation angles, reducing sensing errors and allowing for flexible device layout, as the device can operate effectively regardless of the relative position and magnetic field strengths, thus enhancing precision and cost-effectiveness.
Implementation Method 1
a magnet that is provided to any one rotary shaft out of the first rotary shaft and the second rotary shaft; a first magnetic field sensing unit that is provided to the other rotary shaft different from the one rotary shaft, and outputs a value according to a magnetic field of the magnet
Data Source
AI summary
Disclosed is a relative angle detection device for detecting a relative angle between a first rotary shaft and a second rotary shaft, the relative angle detection device being provided with a first magnetic field sensing unit which outputs a value according to a magnetic field of a magnet, a second magnetic field sensing unit which outputs a value according to the magnetic field of the magnet and outputs a value different from the output value of the first magnetic field sensing unit even if being placed in the same magnetic field as that of the first magnetic field sensing unit, a correction unit which corrects one output value out of the output value of the first magnetic field sensing unit and the output value of the second magnetic field sensing unit in accordance with an amplitude ratio between magnetic field components orthogonal to each other in the magnetic field of the magnet, and a computing unit which computes the relative angle between the first rotary shaft and the second rotary shaft on the basis of the one output value corrected by the correction unit and the other output value different from the one output value. Consequently, a technique capable of detecting the relative rotation angle with high accuracy is provided even if magnitudes of amplitudes of magnetic field components orthogonal to each other in the magnetically sensitive surface of the magnetic field sensing unit are different from each other.