UAV Rotor Speed Synchronization for Noise Reduction

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Solution Overview

Problem

Existing unmanned aerial vehicle (UAV) technologies struggle to record high-quality sound data due to background noise generated by rotor blades, which is distributed across a wide frequency range, leading to the removal of desired sound components during noise filtering.

Innovation Solution

The UAV includes a processor that generates a control request to adjust the rotational speed of rotor blades to minimize the difference between their rotational speeds, thereby narrowing the frequency range of self-generated noise, allowing for effective noise filtering and enhancing sound quality during recording.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If rotor blades rotate at different speeds to maintain flight stability, then flight control flexibility is improved, but noise frequency range expands making sound recording quality deteriorate

Engineering Contradiction:

Improveflight control flexibilityVSAvoidnoise frequency range

Core Design Contradiction:

Adaptability or versatilityVSObject-affected harmful factors

Solution Approach 1:

The system dynamically adjusts rotor blade rotational speeds based on operational mode. During sound recording, the controller synchronizes rotor speeds to minimize frequency range; during normal flight, rotors operate at different speeds for flight control flexibility. This dynamic adaptation resolves the contradiction between flight control needs and noise reduction.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The controller changes the rotational speed parameter of rotor blades based on operational requirements. By adjusting the speed parameter to be synchronized during recording mode and desynchronized during flight mode, the system achieves both flight stability and noise reduction, resolving the technical contradiction.

Inventive Principle:

Principle #35Parameter changes

2Object-affected harmful factors

If background noise is removed through filtering, then noise interference is reduced, but desired sound components are also removed deteriorating sound quality

Engineering Contradiction:

Improvenoise interferenceVSAvoidsound quality

Core Design Contradiction:

Object-affected harmful factorsVSManufacturing precision

Solution Approach 1:

The invention converts the harmful broad-spectrum noise into a beneficial narrow-band noise by synchronizing rotor speeds. This allows the noise to be concentrated in a specific frequency range that can be effectively filtered without removing desired sound components, thus converting the harmful broad noise into a filterable narrow-band noise.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

Solution Approach 2:

The system performs preliminary action by synchronizing rotor blade speeds before sound recording begins. This pre-synchronization narrows the noise frequency range in advance, making subsequent noise filtering more effective and preserving desired sound components, thus resolving the contradiction between noise removal and sound quality.

Inventive Principle:

Principle #10Preliminary action

3Manufacturing precision

If rotor speeds are synchronized to narrow noise frequency range, then sound recording quality is improved, but flight control responsiveness may deteriorate

Engineering Contradiction:

Improvesound recording qualityVSAvoidflight control responsiveness

Core Design Contradiction:

Manufacturing precisionVSSpeed

Solution Approach 1:

The system dynamically switches between synchronized rotor operation during recording and desynchronized operation during normal flight. This dynamic mode switching ensures sound recording quality when needed while maintaining flight control responsiveness during maneuvering, resolving the contradiction between recording quality and control speed.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The controller periodically adjusts rotor speed synchronization based on operational phase. During recording phases, rotors operate synchronously for quality audio; during transition and maneuvering phases, rotors operate independently for responsive control. This periodic adjustment resolves the contradiction between recording quality and control responsiveness.

Inventive Principle:

Principle #19Periodic action

Data Source

PatentUS11469691B2Unmanned aircraft, information processing method, and recording medium

Publication Date: 2022.10.11 PANASONIC INTELLECTUAL PROPERTY MANAGEMENT CO LTD

AI summary

An unmanned aircraft includes: a processor; and at least two generators that generate thrust for the unmanned aircraft to fly, the at least two generators each including a corresponding one of rotor blades that produce airflows. In the unmanned aircraft, the processor generates a control request for changing a rotational speed of at least one of the rotor blades of the at least two generators to reduce a difference between rotational speeds, in response to start of sound recording by a microphone, and the at least two generators rotate the rotor blades in accordance with the control request.