Rotor Craft Noise Cancellation via Electromagnetic Blade Modulation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Rotor-based systems, including drones, generate complex noise patterns due to rotating pressure fields, making it challenging to effectively cancel noise using traditional Active Noise Control (ANC) methods.
Innovation Solution
The implementation of an ANC system that modulates the propeller blades' rotation using embedded magnets and an electromagnetic coil, creating an antiphase amplitude wave to cancel noise. This system includes microphones or oscillation sensors to detect noise and adjust the electromagnetic field to match the phase and rotation pattern of the original noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If traditional Active Noise Control (ANC) methods are used to cancel rotor noise, then noise cancellation is attempted, but the complex phase structure of rotating pressure fields makes effective cancellation difficult to achieve
Solution Approach 1:
The patent replaces traditional acoustic ANC methods (microphones and speakers) with an electromagnetic-mechanical system. Electromagnetic coils generate forces that directly modulate the rotor blades' rotation, creating anti-noise pressure fields through mechanical means rather than acoustic means. This substitution addresses the complex phase structure by directly controlling the source of the rotating pressure field.
Solution Approach 2:
The system changes the operational parameters of the rotor blades by dynamically adjusting their rotation speed and phase using electromagnetic forces. By modifying these parameters in real-time, the system can create anti-noise fields that match the complex phase structure of the original rotor noise, enabling effective cancellation despite the complexity.
2Object-affected harmful factors
If ANC is applied to rotor systems, then noise reduction is achieved, but the system requires insertion of anti-noise source in the heart of the flow which is position-critical and difficult to implement
Solution Approach 1:
The patent merges the anti-noise generation function with the existing rotor blade structure. The electromagnetic coils are integrated into the rotor assembly, allowing the anti-noise source to be positioned exactly at the center of the rotating flow without requiring separate components or complex positioning mechanisms. This integration eliminates the positioning difficulty while maintaining effectiveness.
3Object-affected harmful factors
If conventional ANC uses microphones and speakers to generate anti-noise, then noise cancellation is attempted, but the system cannot effectively address the rotating pressure fields generated by rotor blades
Solution Approach 1:
The patent replaces the acoustic-based ANC system (microphones and speakers) with an electromagnetic-mechanical system that can directly interact with the rotating rotor blades. The electromagnetic coils generate forces that modulate the blade rotation, enabling the system to address rotating pressure fields in a way that conventional acoustic ANC cannot.
Solution Approach 2:
The system implements dynamic control by continuously adjusting the electromagnetic forces applied to the rotor blades in real-time. This dynamic adjustment allows the system to adapt to the changing phase and amplitude of the rotating pressure fields, making the ANC effective for rotor systems where static or simple periodic control would fail.
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 effectively reduces rotor noise by creating destructive interference, achieving noise cancellation through mechanical means, and can be applied to omnidirectional rotors, providing a solution for noise reduction in drones and other rotor-based systems.
Implementation Method 1
The implementation of an ANC system that modulates the propeller blades' rotation using embedded magnets and an electromagnetic coil, creating an antiphase amplitude wave to cancel noise
Implementation Method 2
The noise, like any sound, is composed of alternating compression and rarefaction phases, which the human ear perceives as sound
Implementation Method 3
By creating an inverted sound, with a rarefaction phase during the noise's compression phase and vice versa, the noise pressure wave is cancelled out, reducing the noise
Data Source
AI summary
Rotor noise cancellation through the use of mechanical means for a personal aerial drone vehicle. Active noise cancellation is achieved by creating an antiphase amplitude wave by modulation of the propeller blades, by utilizing embedded magnets through an electromagnetic coil encircling the propeller blades. A noise level sensor signals the rotor control system to adjust the frequency of the electromagnetic field surrounding the rotor and control the speed of the rotor. An additional method comprises of incorporating a phase lock loop within the control system configured to determine the frequencies corresponding to the rotors and generate corrective audio signals to achieve active noise cancellation.