Bias Error Bounds for Positioning Protection Level Calculation

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Solution Overview

Problem

Conventional protection level calculation devices struggle to effectively calculate the protection level for positioning solutions when anomalous measurements are present, leading to invalidity in determining the validity of positioning solutions.

Innovation Solution

A protection level calculation device that includes a bias error model unit to output upper and lower limits of bias errors in measurements from positioning signals, and a protection level calculation unit that uses these limits to determine the validity of positioning solutions.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a multivariate probability distribution model is used to calculate protection level, then the protection level can be derived from measurement data, but the calculation becomes invalid when anomalous measurements are included

Engineering Contradiction:

Improveprotection level calculation validityVSAvoidanomalous measurements

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent extracts and separates the bias error component from the measurement data. By modeling bias error as a distinct parameter with upper and lower limits, the system can identify and handle anomalous measurements without rejecting them entirely, allowing the protection level calculation to remain valid even when anomalies are present in the measurement data.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent changes the approach from using a multivariate probability distribution model to using bias error bounds. Instead of calculating protection level based on probability distributions of measurement errors, the system uses explicit upper and lower limit parameters for bias error, which allows for more robust handling of anomalous measurements while maintaining calculation validity.

Inventive Principle:

Principle #35Parameter changes

2Productivity

If anomalous measurements are rejected to calculate protection level, then the protection level can be calculated, but the calculation becomes ineffective when anomalies cannot be rejected

Engineering Contradiction:

Improveprotection level calculation effectivenessVSAvoidpositioning solution validity determination

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The patent converts the presence of anomalous measurements from a harmful factor into a beneficial diagnostic opportunity. By establishing bias error bounds, the system can identify when measurements are anomalous and understand their impact on the positioning solution, thereby improving the effectiveness of protection level calculation rather than simply rejecting measurements.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

Solution Approach 2:

The patent introduces bias error bounds as an intermediary between the measurement data and the protection level calculation. These bounds act as a mediator that allows the system to process anomalous measurements without compromising the validity determination, enabling effective protection level calculation even when measurements contain anomalies.

Inventive Principle:

Principle #24Intermediary (Mediator)

Data Source

PatentUS20250068496A1Protection level calculation device, protection level calculation system, positioning system, and protection level calculation method

Publication Date: 2025.02.27 MITSUBISHI ELECTRIC CORP

AI summary

A protection level calculation device includes a bias error model unit that outputs the upper limit and the lower limit of a bias error assumed to be contained in a measurement obtained from a positioning signal, and a protection level calculation unit that calculates a protection level for determining the validity of a positioning solution calculated based on the measurement, using the upper limit and the lower limit. The protection level calculation device can calculate the protection level effective for determining the validity of the positioning solution calculated from the measurement.