GPS-Denied Positioning via Terrain Feature Pattern Matching

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Solution Overview

Problem

Current navigation systems face challenges in GPS-denied areas, particularly in environments like forests where prior knowledge and clear views of landmarks are needed for accurate positioning, and existing vision-aided navigation methods are complex and mainly focused on local navigation rather than global geolocation.

Innovation Solution

A computer-implemented method using a navigation processor to obtain local terrain feature location data from sensors like LiDar or cameras, comparing it to global terrain feature data to develop multiple pattern matching hypotheses, determining global location coordinates without prior knowledge, and updating them with inertial measurement unit data, employing a k-closest vector search algorithm and considering uncertainty factors.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If vision-aided navigation is used to match images from horizontal and vertical perspectives, then landmark-based navigation capability is improved, but data processing complexity and system complexity increase significantly

Engineering Contradiction:

Improvepositioning accuracyVSAvoiddata processing complexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The patent extracts and uses only the essential geometric relationships (bearings and distances to landmarks) rather than processing complete images. By taking out only the necessary positional parameters from the complex image data, the system achieves positioning accuracy without the burden of complex image matching algorithms.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

Instead of matching images from different perspectives (horizontal to vertical), the patent inverts the approach by using bearing and distance measurements directly to compute position. This inversion simplifies the problem from complex image processing to straightforward trigonometric calculations.

Inventive Principle:

Principle #13The other way round (Inversion)

2Reliability

If terrain-aided navigation with prior knowledge is used, then positioning reliability is improved, but adaptability to unknown environments deteriorates

Engineering Contradiction:

Improvepositioning reliabilityVSAvoidadaptability to unknown environments

Core Design Contradiction:

ReliabilityVSAdaptability or versatility

Solution Approach 1:

The patent performs preliminary action by pre-computing bearing relationships between landmarks and storing them in a database. This preliminary processing enables rapid positioning when in the environment without requiring complex real-time analysis, thus maintaining reliability while improving adaptability to unknown locations.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The system uses a universal bearing-based approach that works across different environments and terrain types. By relying on fundamental geometric relationships rather than environment-specific features, the navigation method becomes adaptable to various unknown environments while maintaining reliability.

Inventive Principle:

Principle #6Universality (Multi-functionality)

3Ease of operation

If GPS is used for navigation, then positioning speed and ease of operation are improved, but reliability in GPS-denied areas deteriorates to zero

Engineering Contradiction:

Improvenavigation easeVSAvoidpositioning reliability in GPS-denied areas

Core Design Contradiction:

Ease of operationVSReliability

Solution Approach 1:

The patent introduces landmark bearings as an intermediary method between GPS and traditional map reading. By using bearing measurements to known landmarks as a mediator, the system provides GPS-like ease of operation while maintaining reliability in GPS-denied environments through geometric positioning.

Inventive Principle:

Principle #24Intermediary (Mediator)

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 accurate global positioning in GPS-denied areas with minimal equipment and data processing requirements, effectively navigating in environments with multiple terrain features like trees, even without prior position information, by matching local terrain features to existing maps.

Implementation Method 1

The local sensor device may specifically be a LiDar device

Methodology Applied

Scientific EffectLIDAR: LIDAR

Implementation Method 2

a laser range finding device

Methodology Applied

Scientific EffectTime of flight: Time of Flight

Data Source

PatentUS11644527B2Lost-in-forest GPS-denied positioning system

Publication Date: 2023.05.09 THE CHARLES STARK DRAPER LABORATORY INC

AI summary

Local terrain feature location data is obtained from a local sensor device at a user location without a prior-known global position. The local terrain feature location data characterizes relative distances and directions to a plurality of local terrain features nearest to the user location. Global terrain feature location data stored in at least one hardware memory device is accessed. The global terrain feature location data characterizes relative distances and directions between a plurality of distinctive terrain features located in a defined terrain region in terms of absolute global location coordinates. The local terrain feature location data is compared to the global terrain feature location data to develop multiple pattern matching hypotheses, wherein each pattern matching hypothesis characterizes a likelihood of a subset of the local terrain features matching a subset the global terrain features. Global location coordinates for the user location is then determined from the pattern matching hypotheses.