Rotational Angle Detection Circuit Using Coefficient-Based Error Correction

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Solution Overview

Problem

Conventional rotational angle detecting devices require extensive data storage to correct for rotational angle errors caused by disturbance magnetic flux, leading to increased storage needs and preparation time.

Innovation Solution

A rotational angle detecting device with a magnet, magnetic sensor, disturbance magnetic flux detection circuit, and correction circuit that stores data for obtaining coefficients of a relational expression between disturbance magnetic flux and rotational angle error, allowing for correction without storing data for all possible disturbance magnetic flux values.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If data indicating the relationship between disturbance magnetic flux and rotational angle error for all possible disturbance magnetic flux values is stored, then rotational angle error correction accuracy is improved, but data storage volume increases enormously

Engineering Contradiction:

Improverotational angle error correction accuracyVSAvoiddata storage volume

Core Design Contradiction:

Measurement precisionVSQuantity of substance

Solution Approach 1:

The patent transforms the correction approach by changing from storing complete lookup tables to storing only coefficient parameters. The correction circuit uses these parameters to calculate correction values dynamically based on the relational expression between disturbance magnetic flux and rotational angle error, thereby reducing data storage requirements while maintaining correction accuracy.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent extracts only the essential elements (coefficients and relational expressions) from the complete disturbance magnetic flux vs. rotational angle error data set. By storing only these extracted parameters rather than the entire data matrix, the system achieves significant data reduction while preserving the capability to correct rotational angle errors.

Inventive Principle:

Principle #2Taking out (Extraction)

2Reliability

If complete correction data for all disturbance magnetic flux regions is stored, then correction reliability is improved, but data preparation time and effort increase

Engineering Contradiction:

Improvecorrection reliabilityVSAvoiddata preparation time

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

The patent reduces data preparation complexity by transforming comprehensive correction data into concise parameter sets. Instead of measuring and storing correction values for every possible disturbance magnetic flux condition, the system only requires determining the relational expression and its coefficients, significantly reducing preparation time while maintaining correction reliability across all operating regions.

Inventive Principle:

Principle #35Parameter changes

3Adaptability or versatility

If data for all current values in the predetermined current region is stored, then rotational angle error coverage is improved, but storage region size becomes enormous

Engineering Contradiction:

Improverotational angle error coverageVSAvoidstorage region size

Core Design Contradiction:

Adaptability or versatilityVSVolume of stationary object

Solution Approach 1:

The patent creates a universal correction mechanism where the stored coefficients and relational expressions can be applied to calculate correction values for any disturbance magnetic flux value within the operating range. This multi-functional approach allows the system to handle all current values and disturbance regions using a compact set of parameters rather than dedicated data for each condition.

Inventive Principle:

Principle #6Universality (Multi-functionality)

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 effectively suppresses rotational angle errors while reducing the volume of data required for storage, thereby minimizing storage needs and preparation time.

Implementation Method 1

a magnet, disposed on a rotational shaft of a rotating body, which rotates together with the rotational shaft to generate a magnetic flux

Methodology Applied

Scientific EffectElectromagnetic induction: Electromagnetic Induction

Implementation Method 2

a magnetic sensor disposed at a distance from the magnet for detecting the magnetic flux that interlinks with the magnetic sensor

Methodology Applied

Scientific EffectMagnetic field detection: Magnetic Field

Implementation Method 3

a disturbance magnetic flux detection circuit that detects a disturbance magnetic flux interlinking to a magnetic flux that is a flux excluding a magnetic flux generated by the magnet

Methodology Applied

Scientific EffectMagnetic flux detection: Magnetic Field

Data Source

PatentUS10006784B2Rotational angle detecting device

Publication Date: 2018.06.26 DENSO CORP

AI summary

A correction circuit stores data for obtaining coefficients of a relational expression indicating a relationship between a disturbance magnetic flux and a rotational angle error. Then, the coefficients are obtained from the data for obtaining the coefficients, and a detection result of a magnetic sensor is corrected based on the coefficients obtained, a relational expression, and a detection result of a disturbance magnetic flux detection circuit. Since it is possible to obtain the rotational angle error with respect to the disturbance magnetic flux from the coefficient obtained and the relational expression, it is not necessary to store the data indicating the relationship between the disturbance magnetic flux and the rotational angle error for all of the disturbance magnetic flux value in disturbance magnetic flux regions that may be applied.