UAV Motor RPM Randomization for Noise Abatement
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Solution Overview
Problem
Unmanned aerial vehicles (UAVs) generate noise during flight, which can disturb or annoy people, and existing modifications to flight paths do not completely mitigate this issue.
Innovation Solution
The implementation of motor RPM randomization and closed-loop noise control systems in UAVs, which vary the speed of motors to reduce tonal noise by altering the noise signature through randomization or feedback-based adjustments, and the use of movable ballast to modify flight characteristics and reduce noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If flight path modifications are implemented to reduce noise, then noise disturbance to customers is reduced, but the solution is incomplete and still results in some disruption and annoyance
Solution Approach 1:
The patent changes the operational parameters of the UAV motors by randomizing RPM values. Instead of maintaining constant speeds, the system varies motor speeds dynamically, which transforms the noise signature from repetitive tonal patterns to more random broadband noise, thereby reducing annoyance to customers while maintaining flight performance
Solution Approach 2:
The system introduces dynamic behavior to the previously static motor operation. By continuously adjusting motor RPMs based on randomization algorithms, the noise characteristics change over time rather than remaining constant, which effectively reduces the perceptual annoyance of the noise while maintaining productive flight operations
2Object-affected harmful factors
If motor RPM is randomized to reduce tonal noise, then noise annoyance is reduced, but motor speed control precision may be affected
Solution Approach 1:
The patent implements feedback mechanisms where the system monitors motor performance and flight conditions, then adjusts the randomization parameters accordingly. This ensures that while RPM values are randomized to reduce tonal noise, the overall flight performance and speed control precision are maintained through continuous monitoring and adjustment based on actual operating conditions
Data Source
AI summary
This disclosure is directed to varying a speed of one or more motors in an unmanned aerial vehicle (UAV) to reduce unwanted sound (i.e., noise) of the UAV. A UAV may include motors coupled with propellers to provide lift and propulsion to the UAV in various stages of flight, such as while ascending, descending, hovering, or transiting. The motors and propellers may generate noise, which may include a number of noise components such as tonal noise (e.g., a whining noise such as a whistle of a kettle at full boil) and broadband noise (e.g., a complex mixture of sounds of different frequencies, such as the sound of ocean surf). By varying the controls to the motors, such as by varying the speed or revolutions per minute (RPM) of a motor during operation by providing random or pseudo-random RPM variations, the UAV may generate a noise signature with reduced tonal noise.