Bézier Curve Correction for Magnetic Angle Detection
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional angle detection methods using three magnetic sensors for rotational position estimation face challenges in achieving high accuracy due to errors caused by in-phase signals such as third-order, fifth-order, and seventh-order harmonic signals, which cannot be linearized by existing correction processes.
Innovation Solution
The proposed method involves learning processing and angle estimation processing using Bézier curves to correct mechanical angle calculations, where the processing unit acquires and stores learning values for control points that minimize errors, allowing for precise mechanical angle detection despite varying signal bending across segments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional linear correction methods are used for mechanical angle calculation, then the device complexity remains low, but measurement precision deteriorates due to inability to correct harmonic signal errors
Solution Approach 1:
The patent applies Bézier curves, which are mathematical curves used to model non-linear relationships. The correction process uses cubic Bézier curves to represent the error characteristics of magnetic sensor signals, allowing accurate correction of harmonic distortions that cannot be addressed by linear methods. This curvature-based approach enables precise mechanical angle detection by compensating for the non-linear error patterns introduced by third-order, fifth-order, and seventh-order harmonic signals.
2Measurement precision
If Bézier curve correction is applied to all signal segments, then measurement precision improves, but loss of time increases due to extensive learning processing
Solution Approach 1:
The patent divides the mechanical angle range into multiple segments, with each segment having its own Bézier curve correction parameters. The learning process identifies characteristic points (start points, end points, and extreme points) within each segment to define local correction curves. This segmentation allows the system to apply targeted correction only where needed, reducing overall processing time while maintaining high accuracy across the full measurement range.
Solution Approach 2:
The patent performs learning processing during the manufacturing or initialization phase to pre-determine Bézier curve parameters for each segment. These learning values, including control point coordinates and segment boundaries, are stored in memory for rapid retrieval during operation. By completing the complex curve fitting and parameter optimization in advance, the system eliminates time-consuming calculations during real-time mechanical angle detection, achieving both high precision and fast response.
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 significantly reduces the error between estimated and true mechanical angles, enhancing the accuracy of rotational position detection even when signals include complex harmonic components.
Implementation Method 1
acquiring signals output from three magnetic sensors that detect a change in magnetic flux due to rotation of the rotation shaft as sensor signals
Data Source
AI summary
An angle detection device includes: three magnetic sensors detecting a change in magnetic flux due to rotation of a rotation shaft; and a signal processor that acquires sensor signals, generates a linear function θ(Δx) representing a straight line connecting adjacent intersection and zero-cross points, searches for a point where an error between a mechanical angle θ calculated based on the linear function θ(Δx) and a mechanical angle θe acquired from an encoder becomes a maximum value as a maximum error point, calculates a curve based on an origin, a vertex, and a control point, corrects the mechanical angle θ based on the curve, acquires a maximum error between the corrected mechanical angle θ and the mechanical angle θe, and after the value of Δx of the control point is changed in a direction in which the maximum error decreases, returns to the fifth process a predetermined number of times.