Distributed Pheromone Map Search Strategy for UAVs

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Solution Overview

Problem

Existing swarming search strategies for UAVs using pheromone maps are susceptible to local minima, inefficient synchronization, and poor network coverage, leading to suboptimal search coverage and increased susceptibility to agent attrition.

Innovation Solution

A system that creates a digital pheromone map with a distance gradient to guide agents towards unsearched areas, optimizing agent movement and network coverage by synchronizing map updates only when necessary and using behaviors like contour following, avoidance, and gradient descent to ensure exhaustive search coverage.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If a centralized map system is used, then synchronization is simplified, but the system becomes susceptible to network outages and loses reliability

Engineering Contradiction:

Improvesynchronization complexityVSAvoidsystem reliability

Core Design Contradiction:

Device complexityVSReliability

Solution Approach 1:

The patent divides the centralized map into distributed map segments stored across multiple agents. Each agent maintains a local map copy, eliminating the single-point failure vulnerability of centralized systems while distributing the synchronization burden, thus resolving the contradiction between synchronization complexity and system reliability.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent introduces a version number mechanism as an intermediary that mediates synchronization between distributed agents. Agents exchange version numbers to determine whether map updates are needed, reducing unnecessary communication overhead while maintaining consistency across the distributed system, thereby simplifying synchronization without compromising reliability.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Reliability

If a distributed map system is used, then system reliability improves, but sophisticated synchronization strategies are required increasing complexity

Engineering Contradiction:

Improvesystem reliabilityVSAvoidsynchronization complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

Each agent autonomously determines whether it needs to synchronize its map by comparing version numbers with neighboring agents. This self-service approach eliminates the need for complex centralized coordination, allowing each agent to independently manage its own synchronization needs, thus reducing overall system complexity while maintaining reliability.

Inventive Principle:

Principle #25Self-service

3Ease of operation

If agents follow pheromone gradient from high to low concentration, then agents are guided to unsearched areas, but agents get trapped in local minima

Engineering Contradiction:

Improveagent guidanceVSAvoidsearch coverage

Core Design Contradiction:

Ease of operationVSProductivity

Solution Approach 1:

The patent pre-calculates and stores distance-to-unsearched-cell values in each map cell before agents begin their search. This preliminary action creates a distance gradient field that guides agents directly toward unsearched areas, preventing them from getting trapped in local minima by providing global search progress information rather than relying solely on local pheromone gradients.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

Instead of having agents follow pheromone gradients from high to low concentration (which causes local minima trapping), the patent inverts the approach by having agents follow distance gradients from high to low values, where low values indicate proximity to unsearched areas. This inversion transforms the guidance mechanism to actively seek unsearched regions, improving search coverage while maintaining ease of operation.

Inventive Principle:

Principle #13The other way round (Inversion)

4Measurement precision

If agents synchronize map updates frequently, then map accuracy is maintained, but communication overhead increases reducing efficiency

Engineering Contradiction:

Improvemap accuracyVSAvoidsynchronization efficiency

Core Design Contradiction:

Measurement precisionVSProductivity

Solution Approach 1:

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent implements partial synchronization by having agents exchange only the version number information rather than complete map data. This partial action approach maintains map accuracy by tracking changes while significantly reducing communication overhead compared to full map exchanges, thus improving synchronization efficiency without sacrificing map precision.

Inventive Principle:

Principle #16Partial or excessive action

Data Source

PatentUS7856314B2Exhaustive swarming search strategy using distributed pheromone maps

Publication Date: 2010.12.21 THE BOEING CO

AI summary

Method and systems for using agents to perform an operation (e.g., a search) over a geographic area are provided. The system can first create a digital map of the geographic region divided into cells that contain information about the progress of an operation related to the geographic region. Next, the system can calculate a distance gradient of the digital map. The distance gradient indicates the distance from cells of the digital map to the nearest unoperated cell. The system can determine the next move for each agent based on the distance gradient. Also described are methods and systems for efficiently exchanging digital map information among agents and for distributing agents to increase network coverage and decrease agent crowding.