Rotation Angle Detection Device Phase Deviation Correction
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Solution Overview
Problem
Conventional rotation angle detection devices face challenges in accurately calculating rotation angles due to phase deviations between cosine and sine signals from sensor elements, requiring external measurement and increased memory storage for trigonometric functions as signal combinations increase.
Innovation Solution
A rotation angle detection device comprising a sensor circuit, control circuit, and memory circuit that includes sensor element pairs, an output signal acquisition section, pre-correction rotation angle calculation, and phase correction values to correct phase deviations between output signals, allowing for precise rotation angle detection without external measurement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If sensor elements are arranged to produce cosine and sine signals with 90° phase difference, then rotation angle detection precision is improved, but manufacturing precision deteriorates because magnetization direction cannot be confirmed visually
Solution Approach 1:
The system performs self-correction by automatically calculating phase deviation from the detected signals and applying correction values stored in memory, eliminating the need for precise manual arrangement of sensor elements
Solution Approach 2:
The system changes the phase parameter dynamically by calculating the actual phase deviation from the detected cosine and sine signals and applying correction to achieve the required 90° phase difference
2Reliability
If the number of output signals from sensor element pairs is increased, then rotation angle detection reliability is improved, but memory storage capacity requirement increases due to need to store trigonometric functions for all signal combinations
Solution Approach 1:
The system extracts only the necessary correction values for phase deviation from the full set of trigonometric functions, storing only what is needed for correction rather than complete function tables for all signal combinations
Solution Approach 2:
The system pre-calculates and stores correction values in memory during a calibration phase, so that during normal operation only simple lookup and application of these pre-computed values is needed rather than complex real-time trigonometric calculations
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 high-precision detection of rotation angles by correcting phase deviations and reducing memory storage needs, ensuring continuous operation even if some output signals become abnormal.
Implementation Method 1
sensor elements and senses a rotating magnetic field varying with rotation of a detection target and changes impedance in accordance with a rotation angle of the detection target
Data Source
AI summary
A bridge circuit includes a plurality of half-bridges formed of sensor elements, which change impedance in accordance with a rotation angle of a detection target. A control circuit acquires output signals of the half-bridges and calculates a phase correction value for correcting a phase deviation. A memory circuit stores the phase correction value. The control circuit corrects a pre-correction rotation angle by the phase correction value. Since the pre-correction rotation angle is corrected by the phase correction value, a rotation angle of the detection target is detected with high accuracy even if the sensor elements are assembled with some positional deviations.