Odd-Number Magnetic Sensor Array for Rotation Angle Precision
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Solution Overview
Problem
Existing devices for contactless rotation angle measurement using magnetic field sensors require improvement in signal processing precision and often use a large number of sensors, increasing computational effort.
Innovation Solution
A device with an odd number of magnetic field sensors, preferably arranged equiangularly in a circular path, and a signal processing unit that filters the fundamental frequency from the measurement signals to calculate the rotation angle, reducing the demodulation of odd harmonic waves to the fundamental wave and minimizing computational effort.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If an even number of magnetic field sensors is used, then the measurement system can detect the magnetic field at multiple positions, but odd harmonic waves are demodulated to the fundamental wave causing measurement errors
Solution Approach 1:
The patent applies asymmetry by using an odd number of magnetic field sensors instead of the conventional even number. This asymmetric configuration prevents odd harmonic waves from being demodulated to the fundamental wave frequency, thereby eliminating a specific source of measurement error and improving the reliability of rotation angle measurement.
2Measurement precision
If more magnetic field sensors are used to improve measurement precision, then the measurement precision increases, but the computational effort and device complexity increase
Solution Approach 1:
The patent changes the parameter of sensor quantity from an even number to an odd number. This parameter change optimizes the measurement system by preventing harmonic wave demodulation errors while maintaining adequate measurement precision, thereby reducing device complexity and computational effort compared to using a larger even number of sensors.
3Ease of operation
If magnetic field sensors are arranged in a circular path, then the measurement of rotation angle is simplified, but higher frequency components cause angle errors
Solution Approach 1:
The patent extracts and removes higher frequency components (odd harmonic waves) from the measurement signal by using an odd number of sensors arranged in a circular path. This configuration naturally filters out these harmful frequency components, maintaining the simplicity of circular arrangement while improving measurement precision by eliminating angle errors caused by higher frequency components.
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 enhances measurement precision by suppressing higher frequency components, reducing angle errors, and minimizing the number of sensors required, thus optimizing computational efficiency while maintaining accurate rotation angle calculation.
Implementation Method 1
a permanent magnet, an odd number of magnetic field sensors that supply signal values of the measurement signals, wherein the odd number of magnetic field sensors is arranged in a plane below the permanent magnet having either two or four poles
Implementation Method 2
The magnetic field sensors are Hall sensors. These magnetic field sensors can determine the value of a rotation angle from the filtered fundamental frequency.
Data Source
AI summary
A device and method for the processing of a measurement signal of a magnetic field B(φ) is described. The device comprises a permanent magnet having two or four poles, an odd number of magnetic field sensors that are arranged in a plane below the magnets, and a signal processing unit, which is adapted to detect the values of the odd number of magnetic field sensors, to filter the fundamental frequency of the magnetic field out of the detected values of the lateral magnetic field sensors in order to calculate the value of the rotation angle from the fundamental frequency.