Magnetic Shaft Angle Detection with Learned Error Correction
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Solution Overview
Problem
Existing methods for estimating the mechanical angle of a motor's rotation shaft using magnetic sensors are not sufficiently accurate for higher precision requirements.
Innovation Solution
An angle detection method and device utilizing a sensor group of three magnetic sensors and a signal processing unit to perform learning and angle estimation processing, including multiple correction steps to refine sensor signals, improving estimation accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a full-scale rotary encoder is used to achieve high measurement precision, then the angle detection precision is improved, but the device complexity and cost increase
Solution Approach 1:
The rotary encoder is segmented into a master scale and multiple sub-scales with different resolutions. The master scale provides coarse positioning while sub-scales provide fine positioning. This segmentation allows achieving high measurement precision without requiring a full-scale high-resolution encoder, thus reducing device complexity and cost.
Solution Approach 2:
The patent introduces a temporal dimension by using multiple measurement cycles. Instead of relying on a single high-resolution spatial encoding, the system performs multiple measurements with different scale configurations and combines them through signal processing. This transforms a spatial resolution problem into a temporal accumulation problem, achieving high precision without proportionally increasing spatial complexity.
2Measurement precision
If a full-scale rotary encoder is used to achieve high measurement precision, then the angle detection precision is improved, but the cost increases
Solution Approach 1:
The rotary encoder is segmented into a master scale and multiple sub-scales with different resolutions. The master scale provides coarse positioning while sub-scales provide fine positioning. This segmentation allows achieving high measurement precision without requiring a full-scale high-resolution encoder, thus reducing device complexity and cost.
Solution Approach 2:
Instead of using a single expensive high-resolution encoder, the patent creates multiple copies of lower-resolution scales (sub-scales) that work together. Each sub-scale is simpler and cheaper to manufacture, but when combined through the measurement method, they achieve the equivalent precision of a much more expensive single high-resolution encoder.
3Measurement precision
If multiple scales with different resolutions are used to improve measurement precision, then the angle detection precision is improved, but the device complexity increases
Solution Approach 1:
The rotary encoder is segmented into a master scale and multiple sub-scales with different resolutions. The master scale provides coarse positioning while sub-scales provide fine positioning. This segmentation allows achieving high measurement precision without requiring a full-scale high-resolution encoder, thus reducing device complexity and cost.
Solution Approach 2:
The system dynamically switches between different scale configurations during measurement. The master scale and sub-scales are activated in different sequences and combinations depending on the measurement requirements. This dynamic operation allows the system to achieve high precision when needed while maintaining simpler operation for less demanding tasks, effectively managing device complexity.
Data Source
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AI summary
One aspect of an angle detection device of the present invention includes: three magnetic sensors that detect a change in magnetic flux due to rotation of a rotation shaft; and a signal processing unit that processes signals output from the three magnetic sensors. The signal processing unit acquires sensor signals output from three sensor signals, extracts an intersection point at which two sensor signals among the three sensor signals intersect with each other and a zero-cross point at which each of the three sensor signals intersect with a reference signal level, generates a linear function θ(Δx) representing a straight line connecting the intersection point adjacent to each other and the zero-cross point, calculates a deviation between a mechanical angle θ calculated based on the linear function θ(Δx) for a plurality of points on the straight line and a mechanical angle θe acquired from an encoder installed on a rotation shaft as a first angle error, and generates a first angle error function for calculating a first angle error corresponding to an arbitrary point on the straight line based on the first angle error calculated for the plurality of points on the straight line.