Self-Calibrating Multi-Axis Field Sensors Using Cross-Sensor Correlation

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Solution Overview

Problem

Existing methods struggle to accurately calibrate multiple field sensors with skewed sensing axes attached to a rigid body, especially when different types of sensors like acceleration, magnetic field, and force sensors are used, due to external disturbances and the lack of a special measuring device for calibration.

Innovation Solution

A self-calibration method using a processor to obtain and analyze measured values from multiple field sensors, calculating relative rotation matrices and calibration variables based on correlations between sensors to align their frames with a common coordinate system, without requiring an external device.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If multiple field sensors with skewed sensing axes are attached to a rigid body, then three-dimensional vector measurement capability is achieved, but measurement accuracy deteriorates due to axis skewing and external disturbances

Engineering Contradiction:

Improvethree-dimensional vector measurement capabilityVSAvoidmeasurement accuracy

Core Design Contradiction:

Adaptability or versatilityVSMeasurement precision

Solution Approach 1:

The system performs self-calibration by utilizing correlations between measurements from multiple different types of field sensors (acceleration, magnetic field, force sensors) attached to the same rigid body. The calibration process uses the inherent relationships between these sensor types to automatically determine and correct skewing angles without requiring external calibration equipment or specialized measuring devices.

Inventive Principle:

Principle #25Self-service

Solution Approach 2:

The invention changes the calibration approach by transforming from individual sensor calibration to multi-sensor correlated calibration. By analyzing the correlations between measurements from different sensor types under various motion conditions, the system dynamically adjusts calibration parameters (skewing angles) to compensate for axis misalignment and external disturbances.

Inventive Principle:

Principle #35Parameter changes

2Ease of manufacture

If conventional calibration methods are used for each sensor individually, then calibration can be performed, but calibration accuracy deteriorates due to lack of correlation between different sensor frames

Engineering Contradiction:

Improvecalibration process simplicityVSAvoidcalibration accuracy

Core Design Contradiction:

Ease of manufactureVSMeasurement precision

Solution Approach 1:

The invention merges the calibration processes of multiple different field sensor types into a unified calibration framework. By combining acceleration sensor, magnetic field sensor, and force sensor measurements into a single correlated calibration system, the method achieves mutual reinforcement of calibration accuracy while maintaining ease of implementation through integrated processing.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The invention introduces a correlation-based intermediary mechanism that links different sensor frames through their mutual measurements of the same rigid body motion. This correlation acts as a mediator that transfers calibration information between different sensor types, enabling accurate alignment of their respective coordinate systems without requiring direct physical alignment or external reference equipment.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Reliability

If large-scale data acquisition is performed for calibration, then calibration completeness is improved, but system complexity and data processing requirements increase

Engineering Contradiction:

Improvecalibration completenessVSAvoiddata processing complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The invention applies partial action by utilizing the correlated measurements from multiple sensor types during normal operation rather than requiring exhaustive calibration data acquisition. The correlation between different sensor measurements provides sufficient calibration information through routine operations, eliminating the need for extensive specialized calibration procedures while maintaining high calibration completeness.

Inventive Principle:

Principle #16Partial or excessive action

Data Source

PatentUS11442118B2Method for self-calibrating multiple field sensors having three or more sensing axes and system performing the same

Publication Date: 2022.09.13 INTELLECTUAL DISCOVERY CO LTD

AI summary

Embodiments relate to a method including obtaining m measured values for each field sensor by measuring with respect to a first sensor group including first type of field sensors and a second sensor group including different second type of field sensors, which are attached to the rigid body, at m time steps; and calibrating a sensor frame of the first type of field sensor and a sensor frame of the second type of field sensor by using a correlation between the first type of field sensor and the second type of field sensor based on measured values of at least some of the m time steps, wherein the multiple field sensors include different field sensors of a magnetic field sensor, an acceleration sensor, and a force sensor, and a system therefor.