IMU Position Correction via Loop-Closure Drift Compensation

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Solution Overview

Problem

Existing position determination systems, such as laser-based systems, are limited to line-of-sight measurements and cannot accurately determine position information in interior or occluded areas of large structures like aircraft, making it difficult to assemble or maintain components within these areas.

Innovation Solution

A portable device equipped with an inertial measurement unit (IMU) that gathers acceleration and rotational data to calculate position estimates, using numerical integration and drift correction algorithms to correct errors and determine positions in areas inaccessible to traditional systems.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If laser-based position determination systems are used, then measurement precision is improved for line-of-sight areas, but the system cannot determine positions in occluded areas

Engineering Contradiction:

Improveposition determination accuracyVSAvoidcoverage area

Core Design Contradiction:

Measurement precisionVSAdaptability or versatility

Solution Approach 1:

The patent introduces an inertial measurement unit (IMU) as an intermediary device that carries position determination capabilities into occluded areas where laser-based systems cannot reach. The IMU measures acceleration and uses numerical integration to calculate position estimates in areas inaccessible to traditional line-of-sight systems, thereby extending the coverage while maintaining measurement capability

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent replaces the optical laser-based measurement system with an inertial measurement system based on acceleration sensing and mathematical integration. This substitution allows the system to operate independently of line-of-sight requirements, enabling position determination in occluded areas while providing comparable or sufficient precision for assembly and maintenance applications

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Adaptability or versatility

If inertial measurement units are used to determine positions in occluded areas, then coverage area is improved, but measurement precision deteriorates due to drift errors

Engineering Contradiction:

Improvecoverage areaVSAvoidposition determination accuracy

Core Design Contradiction:

Adaptability or versatilityVSMeasurement precision

Solution Approach 1:

The patent implements a feedback mechanism where the IMU system continuously monitors its own position estimates and compares them against expected positions or reference points. When drift errors are detected, the system uses this feedback information to correct subsequent measurements, thereby maintaining measurement precision over extended periods and distances in occluded areas

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The patent applies preliminary drift correction algorithms that anticipate and compensate for integration errors before they significantly degrade position accuracy. By pre-correcting for expected drift based on motion patterns and environmental factors, the system maintains higher precision in position determination throughout the measurement period

Inventive Principle:

Principle #10Preliminary action

3Device complexity

If traditional line-of-sight position determination systems are used, then device complexity is reduced, but ease of operation deteriorates in occluded areas

Engineering Contradiction:

Improvesystem structureVSAvoidusability in occluded areas

Core Design Contradiction:

Device complexityVSEase of operation

Solution Approach 1:

The patent creates a universal position determination system that combines both laser-based measurement capabilities for open areas and IMU-based inertial navigation for occluded areas. This multi-functional system can automatically switch between or integrate both methods, providing ease of operation across all environments without requiring separate specialized equipment for different measurement scenarios

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

Enables precise determination of positions within occluded areas, reducing assembly and maintenance errors by up to 1% margin, allowing for accurate placement and identification of components inside large structures.

Implementation Method 1

gathering acceleration data as the IMU is moved to an intermediate location

Methodology Applied

Scientific EffectInertial measurement: Accelerometer

Data Source

PatentUS9423250B1Position measurement correction using loop-closure and movement data

Publication Date: 2016.08.23 THE BOEING CO

AI summary

A method includes initializing an inertial measurement unit (IMU) at a starting location and gathering acceleration and rotational data as the IMU is moved to an intermediate location. An indication that the IMU is at the intermediate location is received. The method includes gathering acceleration and rotational data as the IMU is moved to an ending location and calculating a position of the ending location based on a known position of the starting location and the acceleration data. The method includes calculating corrected acceleration data based on a difference between the calculated position of the ending location and a known position of the ending location, and calculating a position of the intermediate location based on the corrected acceleration data are provided.