Geolocation System Flexure Compensation via Inertial Measurement

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Solution Overview

Problem

Existing geolocation systems face significant errors in determining the location of a signal emitter due to the flexing of airplane wings, which introduces inaccuracies in baseline vector calculations, limiting their effectiveness on flexible platforms like modern aircraft.

Innovation Solution

A method and system that utilize inertial navigation data and inertial measurement units to calculate the velocity and position of detectors on flexible portions of a platform, combined with a filtering operation to null flexure motion measurements, allowing for accurate determination of a signal emitter's position by separating flexure motion from residual calculations.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If antennas are positioned on the wings of the airplane, then the geolocation system can function with the required baseline configuration, but the wing flexure introduces significant errors into the location determination

Engineering Contradiction:
Improveability to function on flexible platformVSAvoidlocation determination accuracy
Core Design Contradiction:
Adaptability or versatilityVSMeasurement precision

Solution Approach 1:

The system uses inertial measurement units (IMUs) to continuously monitor the position and orientation of antennas on flexing wings, feeding this motion data back to the geolocation processor. This feedback loop enables real-time compensation for wing flexure, allowing the system to maintain measurement precision despite the flexible platform. The IMUs provide continuous information about baseline vector changes, which are then used to correct geolocation calculations.

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

Inertial measurement units serve as intermediary devices between the flexible wing structure and the geolocation system. These IMUs measure the actual motion and deformation of the wing-mounted antennas, acting as a mediator that translates physical flexure into quantifiable data. This intermediary measurement layer enables the system to account for and compensate for the effects of wing flexure on baseline accuracy.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Measurement precision

If the baseline is shortened to reduce flexure effects, then measurement accuracy improves, but the geolocation system loses effectiveness

Engineering Contradiction:
Improvelocation determination accuracyVSAvoidgeolocation system effectiveness
Core Design Contradiction:
Measurement precisionVSProductivity

Solution Approach 1:

Rather than shortening the baseline, the system implements feedback through IMUs that continuously track the actual baseline vector despite its length and flexibility. This feedback mechanism allows the system to maintain long baselines for geometric strength while compensating for their flexure-induced errors, thus preserving both effectiveness and accuracy.

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The system dynamically adjusts the baseline vector parameters (length, orientation, position) based on real-time IMU measurements of wing flexure. By changing these parameters according to actual measured conditions rather than assuming a fixed baseline, the system maintains accuracy despite using long, flexible baselines mounted on the wings.

Inventive Principle:
Principle #35Parameter changes

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 significantly increases the accuracy of signal emitter location determination by compensating for wing flexure, providing a more precise geolocation solution even on flexible platforms like aircraft, enhancing the system's performance and observability without affecting accuracy.

Implementation Method 1

inertial measurement units to calculate a velocity and a position of detectors on the flexing portion

Methodology Applied
Scientific EffectInertial measurement: Accelerometer

Implementation Method 2

a filtering operation of a filter having notches set to vibrational modes defined in the flexure relationship data, whereby the flexure motion measurements are separated

Methodology Applied
Scientific EffectVibration: Vibration

Data Source

PatentEP3427078B1Geolocation on a single platform having flexible portions
Publication Date: 2020.03.11 RAYTHEON CO
  • EP3427078B1 patent drawingFigure 1.1~1.3
  • EP3427078B1 patent drawingFigure 2
  • EP3427078B1 patent drawingFigure 3

AI summary

A geolocation system on a platform, for example, an airplane, to identify a location of a signal emitting site includes an inertial navigation system and an array of signal detectors. A first subset of the detectors is on a flexing portion of the platform and a second subset of detectors is on a rigid portion of the platform. An inertial measurement unit is disposed adjacent to each of the detectors on the flexing portion. A locator module is configured to: calculate a respective velocity and a respective position of each one of the detectors positioned on the flexing portion as a function of respective inertial measurement data; and determine a position of the emitter as a function of the calculated velocity, calculated position, inertial navigation data, the detected signal data and data defining a flexure relationship between the flexing and rigid portions of the platform.