81results about "Active noise reduction system" patented technology

Noises that are to be emitted by an aerial vehicle during operations may be predicted using one or more machine learning systems, algorithms or techniques. Anti-noises having equal or similar intensities and equal but out-of-phase frequencies may be identified and generated based on the predicted noises, thereby reducing or eliminating the net effect of the noises. The machine learning systems, algorithms or techniques used to predict such noises may be trained using emitted sound pressure levels observed during prior operations of aerial vehicles, as well as environmental conditions, operational characteristics of the aerial vehicles or locations of the aerial vehicles during such prior operations. Anti-noises may be identified and generated based on an overall sound profile of the aerial vehicle, or on individual sounds emitted by the aerial vehicle by discrete sources.

The present invention includes an a plurality of first variable speed motors arranged in a first matrix pattern and mounted on a tail boom of the helicopter; one or more fixed pitch blades attached to each of the plurality of first variable speed motors; and wherein a speed of one or more of the plurality of first variable speed motors is varied to provide an anti-torque thrust.

An unmanned aerial vehicle (UAV) may emit masking sounds during operation of the UAV to mask other sounds generated by the UAV during operation. The UAV may be used to deliver items to a residence or other location associated with a customer. The UAV may emit sounds that mask the conventional sounds generated by the propellers and/or motors to cause the UAV to emit sounds that are pleasing to bystanders or do not annoy the bystanders. The UAV may emit sounds using speakers or other sound generating devices, such as fins, reeds, whistles, or other devices which may cause sound to be emitted from the UAV. Noise canceling algorithms may be used to cancel at least some of the conventional noise generated by operation of the UAV using inverted sounds, while additional sound may be emitted by the UAV, which may not be subject to noise cancelation.

Disclosed is a system for controlling acoustic radiation from an aircraft. The system comprising a plurality of rotor systems (one or more) and a noise controller configured to regulate acoustic radiation from the plurality of rotor systems. The noise controller can be configured to regulate a commanded flight setting from the flight control system and to output a regulated flight setting to the plurality of rotor systems. Based on the regulated flight setting, the plurality of rotor systems are configured to generate, individually and in aggregate, acoustic radiation having a target acoustic behavior. The target acoustic behavior may be achieved using beamforming techniques to, for example, change the directionality of acoustic radiation from the plurality of rotor systems, or otherwise tune the acoustic radiation to reduce detectability and/or annoyance.

A propeller system for an aircraft includes an assembly for modifying a sound field of the propeller system. The propeller system includes a rotor supported for rotation about a rotor axis. The rotor has a central hub and a plurality of blades each extending outwardly from the hub to a tip. The rotor and blades are operable to propel an aircraft to travel in a direction. The rotor blades define a rotor plane perpendicular to the rotor axis. The blade tips define a circumferential rotational path as the blades are rotated by the rotor. The propeller system includes an acoustic resonator or multiple resonators having openings disposed within a distance to the propeller blade tip that is small compared to the wavelength of the propeller's fundamental blade tone and proximate to the rotor plane. The resonators are excited by tip flow of the blade as it passes the opening. The acoustic resonators are configured and positioned so as to direct acoustic energy to modify the sound field of the propeller system at blade pass or higher harmonic frequency tones in a desired direction relative to the aircraft.

An active pylon noise control system for an aircraft includes a pylon structure connecting an engine system with an airframe surface of the aircraft and having at least one aperture to supply a gas or fluid therethrough, an intake portion attached to the pylon structure to intake a gas or fluid, a regulator connected with the intake portion via a plurality of pipes, to regulate a pressure of the gas or fluid, a plenum chamber formed within the pylon structure and connected with the regulator, and configured to receive the gas or fluid as regulated by the regulator, and a plurality of injectors in communication with the plenum chamber to actively inject the gas or fluid through the plurality of apertures of the pylon structure.

Vertical and/or lateral acceleration sensors are mounted in or on the engines or pylons of an aircraft to measure the vibrations induced by the operating dynamics of the engines. The sensors provide measured vibration signals to a controller that generates control signals in response to and dependent on the measured vibration signals. The control signals are provided to the aileron actuators, so as to actuate the ailerons appropriately to counteract and thereby reduce the engine-induced vibrations. Thus, the engine-induced vibrations acting on the fuselage are diminished and the passenger flight comfort is significantly improved.

A drone-based audio system comprising a microphone mounted to a drone body for receiving environmental sound information. The drone-based audio system additionally comprising a processing unit configured to analyze the environmental sound information and calculate active noise cancellation information. The drone-based audio system further comprising a speaker mounted to the drone body for emitting the active noise cancellation information.

A method for damping vibrations in a tail boom of a rotary-wing aircraft includes the steps of detecting tail boom vibrations induced by external vibration excitation, and generating and introducing strains into the tail boom based on the detected tail boom vibrations. The strains are applied over a surface area and are out-of-phase with respect to the detected tail boom vibrations so as to damp the externally excited induced tail boom vibrations. In addition, a rotary-wing aircraft, includes a fuselage, a cockpit area integrated into the fuselage, a tail boom arranged on the fuselage and a tail boom vibration-damping device. The vibration-damping device has at least one sensor element configured to detect tail boom vibrations induced by external vibration excitation and at least one actuator configured to generate and introduce strains into the tail boom that are out-of-phase with respect to the induced tail boom vibrations, the actuator being functionally coupled to the sensor element, engaging with a tail boom structure at one side of the tail boom, and forming a flat-surfaced bond with the tail boom.

Methods and apparatus for suppressing noise. The present invention provides a method that includes directing a laser at a first volume of gas and directing microwave radiation to a second volume. The method includes selecting the location of the second volume so that it is overrun by a shockwave system of a supersonic vehicle. Preferably, the directing of the radiation is from a vehicle that flies at high altitude and is of practical length (e.g., 100-400 feet or more). The radiation may be pulsed and steered. The present invention also provides a system including a laser and microwave antenna for controlling the noise of a supersonic vehicle. The laser is directed at a first volume while the antenna is pointed at a second volume that envelops the first volume. The location of the second volume is such that it will be overrun by the shockwave system of the vehicle.

A noise control system for a ducted rotor assembly, the ducted rotor assembly including a hub, a duct, and two or more blades coupled to the hub and supported by the duct. The noise control system including a microphone configured to receive a sound input generated by the ducted rotor assembly, the microphone configured for association with the hub; a speaker unit configured to generate a cancellation noise, the speaker configured for association with the hub; and a controller operably connected to the microphone and the speaker unit, the controller configured to selectively adjust harmonics of the cancellation noise to reduce an acoustic signature of the ducted rotor assembly. In another aspect, there is provided a rotorcraft with a ducted rotor assembly in a tail portion including a noise control system. In a third aspect, there is a method of reducing an acoustic signature of a ducted rotor assembly.

Vibrations due to excitation of the natural modes of an aircraft's body are suppressed by an active multi-axis modal suppression system. Dedicated sensors are positioned in the aircraft at optimal locations for sensing modal induced vibrations. The sensor produced signals are processed through control logic which, in response thereto, and in response to aircraft inertial, velocity and altitude related signals produces output control signals. The control signals effect control surface deployment creating forces to suppress the natural mode induced vibrations on multiple geometric axis's. More particularly, symmetric and anti-symmetric control surface deployments are used on one or more geometric axis's to damp lateral, longitudinal, vertical and most importantly torsional vibrational modes.

Various embodiments provide systems and methods for noise reduction for lift-augmentation wing-sections (e.g., flaps, slats, elevons, etc.) by the use of flow disruption devices placed upstream of vortex generation locations. The flow disruption devices may reduce the noise radiating from side edges of lift-augmentation control wing sections. An embodiment flow disruption device may include a body configured to protrude into a flow over a vehicle's surface, wherein the body is coupled to the vehicle upstream of a side edge of a structure of the vehicle such that a wake produced by the body introduces unsteadiness and a flow velocity deficit in a vortex formation region of the side edge of the structure.

Techniques for using an unmanned aerial vehicle (UAV) to deliver a payload while reducing and/or altering sound generated by the UAV during delivery may be provided. For example, during delivery, the UAV may be instructed to utilize one or more sets of propellers of different sizes to reduce and/or alter the sound generated by and/or around the UAV. Intrinsic and extrinsic information associated with the UAV may be utilized to dynamically adjust the particular sets of propellers of a certain and different size to utilize during different portions of a flight path while delivering the payload.

The invention discloses a multi-rotor aircraft noise suppression method based on phase angle control, and the method comprises the following steps that a system obtains the three-dimensional coordinates of a target noise reduction position, and transmits the position information to a noise prediction module; the flight control module takes the attitude angle and the speed as characteristic parameters and sends the characteristic parameters to the noise prediction module; the noise prediction module calculates noise information generated by a rotor at a target position through a rapid noise prediction method and sends the noise information to the phase angle optimization module; the phase angle optimization module obtains an optimal phase angle combination based on an optimization algorithmand sends the optimal phase angle combination to the phase synchronization control module; and the phase synchronization control module adjusts the phase angle positions of the plurality of rotors according to the received optimal phase angle combination in combination with the phase angle position information to realize noise reduction of the target position. According to the invention, the target function can be adjusted and optimized according to the noise reduction requirement, and compared with a passive noise reduction method, the method of the invention can control noise components ina targeted mode and has a better inhibition effect on multi-rotor-wing low-frequency-band noise.