Power Steering Angle Detection with Harmonic Signal Correction
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Solution Overview
Problem
Existing rotation angle detection devices fail to accurately detect angles when sine and cosine signals include frequency components other than fundamental waves, leading to errors in the detected rotation angle.
Innovation Solution
A rotation angle detection device that includes a coefficient identification unit to identify frequency components in sine and cosine signals, a correction value calculation unit to calculate correction values, and a rotation angle calculation unit to correct the signals using these values, thereby suppressing errors caused by non-fundamental frequency components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the rotation angle detection device uses sine signal and cosine signal to detect rotation angle, then the detection method is simple and widely applicable, but when frequency components other than fundamental waves are included in the signals, detection error occurs
Solution Approach 1:
The patent segments the frequency components of the sine and cosine signals by using Fast Fourier Transform (FFT) to separate the fundamental wave components from harmonic components. This segmentation allows the system to identify and eliminate the effect of non-fundamental frequency components that cause detection errors, thereby maintaining measurement precision while keeping the detection method relatively simple.
Solution Approach 2:
The patent introduces an intermediary processing stage between signal acquisition and angle calculation. This intermediary includes FFT analysis to identify frequency components and a correction mechanism that compensates for harmonic distortions. This intermediary layer acts as a mediator that filters out erroneous frequency components before they affect the final rotation angle detection accuracy.
2Measurement precision
If the device corrects for frequency components other than fundamental waves, then detection accuracy improves, but device complexity increases
Solution Approach 1:
The patent replaces complex hardware-based frequency filtering mechanisms with software-based digital signal processing. By using FFT algorithms and digital correction methods, the system achieves frequency component separation and error compensation through computational means rather than mechanical or analog circuitry, thereby improving accuracy without proportionally increasing physical device complexity.
Solution Approach 2:
The patent changes the processing parameters of the sine and cosine signals by applying FFT transformation and identifying specific frequency components. This parameter-based approach allows the system to adaptively correct for harmonic distortions by modifying the signal representation in the frequency domain, achieving high detection accuracy through parameter manipulation rather than complex structural modifications.
Data Source
AI summary
Provided is a rotation angle detection device including: a coefficient identification unit configured to identify, based on a sine signal and a cosine signal which are based on a rotation angle of a rotating body, coefficients of frequency components included in the sine signal and the cosine signal; a correction value calculation unit; and a rotation angle calculation unit. The coefficient identification unit is configured to identify, for each of integers M and N which satisfy a relationship in which M+N is equal to a positive constant, and each of which is equal to or larger than 0, a coefficient of each of (M+N−1)th order components included in the sine signal and the cosine signal, based on results of application of low-pass filters to products of an M-th power of the sine signal and an N-th power of the cosine signal.