Rotating Microphone Doppler Tracking for UAV Collision Avoidance

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Solution Overview

Problem

Small unmanned aerial vehicles (UAVs) lack the weight capacity for radar-based collision avoidance systems, and ground-based UAV tracking systems struggle to locate all UAVs in a dense swarm, while fixed microphone arrays require a significant footprint and passive radar tracking is limited to scenarios where UAVs emit RF signals, leading to interference issues.

Innovation Solution

A method using pre-existing propellers on UAVs with Doppler-based acoustic tracking, where a rotating microphone attached to the propeller blade tip measures frequency shifts to calculate the location of acoustic sources in three dimensions, allowing for collision avoidance and navigation without the need for radar systems.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If radar-based collision avoidance systems are employed on UAVs, then collision avoidance capability is improved, but weight capacity is exceeded

Engineering Contradiction:

Improvecollision avoidance capabilityVSAvoidweight capacity

Core Design Contradiction:

ReliabilityVSWeight of moving object

Solution Approach 1:

The patent replaces radar-based collision avoidance systems with an acoustic tracking system using microphones and Doppler effect analysis. This substitution eliminates the need for heavy radar equipment on UAVs while maintaining collision avoidance capability through acoustic source localization algorithms.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent uses pre-existing propellers on UAVs as acoustic sources without requiring additional active transmitters. By treating the propellers themselves as the acoustic signaling elements, the system avoids adding weight while maintaining tracking capability.

Inventive Principle:

Principle #26Copying

2Measurement precision

If ground-based UAV tracking systems are used, then tracking capability is improved, but ability to locate all UAVs in dense swarm deteriorates

Engineering Contradiction:

Improvetracking capabilityVSAvoidability to locate all UAVs in dense swarm

Core Design Contradiction:

Measurement precisionVSProductivity

Solution Approach 1:

The patent divides the tracking task into individual UAV-level acoustic sources, allowing each UAV to be tracked independently through its propeller acoustic signature. This segmentation enables the system to handle dense swarms by processing multiple independent acoustic sources simultaneously.

Inventive Principle:

Principle #1Segmentation

3Measurement precision

If fixed array of microphones is deployed, then acoustic tracking capability is improved, but footprint requirement increases

Engineering Contradiction:

Improveacoustic tracking capabilityVSAvoidfootprint

Core Design Contradiction:

Measurement precisionVSArea of stationary object

Solution Approach 1:

The patent transitions from a static fixed microphone array to a dynamic rotating microphone system. The microphone is mounted on a rotating member that sweeps through different angular positions, enabling three-dimensional acoustic source localization with a compact footprint by utilizing temporal and angular information from the rotation.

Inventive Principle:

Principle #15Dynamics

4Measurement precision

If passive radar tracking is used, then tracking capability is improved, but applicability is limited to scenarios where UAV emits RF signal

Engineering Contradiction:

Improvetracking capabilityVSAvoidapplicability to different scenarios

Core Design Contradiction:

Measurement precisionVSAdaptability or versatility

Solution Approach 1:

The patent replaces RF-based passive radar tracking with acoustic-based tracking using microphone arrays and Doppler analysis. This substitution broadens applicability to all UAVs with acoustic-emitting components (propellers) regardless of their RF signal emission status, enabling universal tracking capability.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

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 provides a lightweight, low-cost, and compact tracking system capable of accurately determining the location of nearby UAVs, enabling effective collision avoidance and navigation, even in dense swarms, with minimal interference and no requirement for RF signal emission.

Implementation Method 1

Doppler-based acoustic tracking, where a rotating microphone attached to the propeller blade tip measures frequency shifts

Methodology Applied

Scientific EffectDoppler effect: Doppler Effect

Data Source

PatentUS10935630B2Method for three-dimensional tracking of sinusoidal acoustic source using a rotating microphone

Publication Date: 2021.03.02 THE UNITED STATES OF AMERICA AS REPRESENTED BY THE SECRETARY OF THE NAVY

AI summary

A method for determining the location of a first source. A first member is provided. A first tip microphone is attached to a first end of the first member. A first static microphone is provided. An initial frequency is recorded at the static microphone. The first member is rotated at an angular velocity. A tangential distance is calculated from the first tip microphone to the source. A source angle is calculated from the first member to the source. A height of the source is calculated.