Rotor craft noise cancellation system and method
View Patent ↗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.
1 . A method for noise reduction in connection with a rotating fan system with propellers wherein said propellers include magnetic portions and wherein said magnetic portions interact with an electromagnet wherein said propellers produce noise and vibrations, the method comprising:
sensing the noise and vibrations produced by the propellers;
triggering modulation of the rotation of propeller blades, wherein rotation is optimized in terms of positive and negative compression towards and away from a listener, and
wherein said propellers rotated by a motor independent of energy generated by said electromagnet,
wherein said sensing occurs via microphone installments to an inner rim of the propellers encircling a rotor such that as the propeller blades rotate they are noise sensed;
creating interference using the electromagnet acting upon said rotation of said propellers so that said interference acting upon said rotation of said propellers is controlled so as to enable said propellers to maintain a desired rate of rotation,
wherein said interference is the result of generating an antiphase amplitude wave, and
wherein a desired rate of rotation can be achieved by control of rotor angles or varying rotational speed to influence sound pressure and a transported amount of air in each sound wave.
2 . The method of claim 1 wherein said propellers are manufactured with magnetic portions embedded within an electromagnetic coil, the coil being mounted to a inner rotor frame which encircles a plurality of rotors, with magnets fixed to the ends of said rotors.
3 . The method of claim 1 wherein magnets are attached to said propellers.
4 . The method of claim 1 wherein electronic waves are input to said electromagnet to modify movement of said propellers and include a feedback system so as to reduce said interference in proportion to environmental conditions and for comparatively reducing noise in proportion to maintaining a desired rate of rotation of said propellers.
5 . The method of claim 1 wherein interference is produced in a manner to achieve variable said noise reduction.
6 . An aerial drone with propeller noise reduction including reducing propeller noise by magnetizing propellers, the aerial drone comprising:
an electromagnet for creating interference acting upon a rotation of said propellers and applying an orthogonal magnetic field to an electrical field of said propellers to cancel noise;
a motor for rotating said propellers independent of energy generated by the electromagnet;
an oscillation sensor for mitigating noise interference from wind and exterior elements by compensating for rotations per minute, air density and speed;
wherein said rotating propeller system reacts in proportion to said interference acting upon said rotation of said propellers; and
wherein a produced antiresonance is independent of oscillator properties which controls said electric field.
7 . The aerial drone of claim 6 wherein said propellers are manufactured with magnetic portions.
8 . The aerial drone of claim 6 wherein magnets are attached to said propellers.
9 . The aerial drone of claim 6 wherein an electronic wave is input to said electromagnet to modify the movement of said propellers and include a feedback system so as to maintain a desired rate of rotation of said propellers wherein the magnets can be both generators of energy and may be acted upon as they rotate by electromagnetic coils.
10 . The aerial drone of claim 6 wherein said interference is produced in a manner to achieve variable noise reduction.
11 . A rotating fan system with propellers disposed upon an aerial drone wherein said propellers include magnetic portions and wherein said magnetic portions interact with an electromagnet wherein said propellers are rotated by a motor independent of energy generated by said electromagnet and wherein said electromagnet creates interference acting upon said rotation of said propellers, wherein said rotating fan system includes a position shift detector of said aerial drone so that said interference acting upon said rotation of said propellers is minimized so as to enable said aerial drone to maintain a steady position above a terrestrial target of interest.
12 . The system of claim 11 wherein said propellers are manufactured with magnetic portions.
13 . The system of claim 11 wherein magnets are attached to said propellers.
14 . The system of claim 11 wherein electronic waves are input to said electromagnet to modify the movement of said propellers and include a phase lock loop system so as to reduce said magnetic interference in proportion to said wind or other environmental conditions and for comparatively reducing noise in proportion to maintaining a steady position of said aerial drone above said terrestrial target of interest so as to minimize said noise but to sacrifice said noise reduction just enough to maintain said position of said aerial drone above said terrestrial target of interest.
15 . The system of claim 11 wherein said interference is produced in a manner to achieve noise reduction.
16 . The system of claim 15 wherein said noise reduction is maximized by varying said magnetic interference so as to minimize overall noise amplitude produced by said system during use.
17 . The system of claim 15 wherein active noise cancelation ANC is used to reduce said noise.
18 . The system of claim 15 wherein microphones are used to sense said noise.
19 . The system of claim 11 wherein a sound level of generated sound can either be controlled by different rotor angles or by varying the rotational speed for influencing sound pressure and an amount of transported air in each sound wave.
20 . The system of claim 19 wherein an algorithm that compensates for rotations per minute (RPM) and air density and speed controls an electronic oscillator which in turn controls production of an electronic field through coils surrounding a propeller rotor.