Angle Detection via Sum-Difference Signals for Second-Order Error Suppression

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Existing angle detection methods fail to effectively reduce rotation second-order angle errors caused by phase differences between sine and cosine signals deviating from π/2.

Innovation Solution

An angle detection device that includes an angle detector for sensing sine signals with different phases, a detection signal calculation unit to generate detection signals from the sum and difference of these sine signals, and an angle calculation unit to suppress second-order angle errors by ensuring orthogonality between the detection signals.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If conventional angle detection methods using sine and cosine signals are used, then offset errors and amplitude ratio errors can be corrected, but rotation second-order angle errors due to phase difference deviation from π/2 cannot be reduced

Engineering Contradiction:

Improveangle detection accuracyVSAvoidrobustness against phase difference errors

Core Design Contradiction:

Measurement precisionVSReliability

Solution Approach 1:

The patent transforms the phase difference parameter issue into an amplitude ratio issue. By using the sum and difference of two sine signals with phase difference γ to create detection signals, the method changes the parameter representation such that the orthogonality condition becomes independent of the original phase difference γ, thereby resolving the sensitivity to phase deviation

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent replaces the traditional mechanical assumption of exact π/2 phase difference with a mathematical transformation system. Instead of relying on precise mechanical phase alignment, the system uses signal processing (sum and difference operations) to achieve orthogonality, substituting mechanical precision requirements with computational robustness

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Device complexity

If the phase difference between sine and cosine signals deviates from π/2, then the angle detection system becomes simpler to implement, but rotation second-order angle errors increase

Engineering Contradiction:

Improvesignal processing complexityVSAvoidangle detection accuracy

Core Design Contradiction:

Device complexityVSMeasurement precision

Solution Approach 1:

The detection signal generation system performs self-correction by using the sum and difference of the two sine signals. The mathematical transformation inherently compensates for phase difference deviations without requiring external calibration or complex correction algorithms, making the system self-adjusting to phase variations

Inventive Principle:

Principle #25Self-service

Data Source

PatentUS12345553B2Angle detection device

Publication Date: 2025.07.01 MITSUBISHI ELECTRIC CORP

AI summary

There has been a problem that a rotation second-order angle error due to a phase difference between a sine signal and a cosine signal deviating from π/2 cannot be reduced. Therefore, provided is an angle detection device that can suppress a second-order angle error caused due to the phase difference between a first sine signal and a second sine signal deviating from π/2, by calculating a detection angle from a first detection signal based on the sum of two sine signals having different phases and a second detection signal based on the difference of the two sine signals.