NZ742287A - Systems and methods for acoustic radiation control - Google Patents
Systems and methods for acoustic radiation controlInfo
- Publication number
- NZ742287A NZ742287A NZ742287A NZ74228718A NZ742287A NZ 742287 A NZ742287 A NZ 742287A NZ 742287 A NZ742287 A NZ 742287A NZ 74228718 A NZ74228718 A NZ 74228718A NZ 742287 A NZ742287 A NZ 742287A
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- New Zealand
- Prior art keywords
- rotor
- noise
- flight
- acoustic
- acoustic radiation
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Abstract
Disclosed is a system for controlling acoustic radiation from an aircraft. The system comprising a plurality of rotor systems (one or more) (126) and a noise controller (102) configured to regulate acoustic radiation from the plurality of rotor systems (126). The noise controller (102) can be configured to regulate a commanded flight setting from the flight control system and to output a regulated flight setting (108a) to the plurality of rotor systems (126). Based on the regulated flight setting, the plurality of rotor systems (126) are configured to generate, individually and in aggregate, acoustic radiation having a target acoustic behavior (108a). The target acoustic behavior (108a) 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. ured to regulate a commanded flight setting from the flight control system and to output a regulated flight setting (108a) to the plurality of rotor systems (126). Based on the regulated flight setting, the plurality of rotor systems (126) are configured to generate, individually and in aggregate, acoustic radiation having a target acoustic behavior (108a). The target acoustic behavior (108a) 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.
Description
SYSTEMS AND METHODS FOR ACOUSTIC RADIATION CONTROL
TECHNICAL FIELD
The present invention relates to a system and method for controlling acoustic
radiation, more specifically to a system and method for controlling the acoustic radiation
generated and/or emitted by an aircraft’s propellers, fans, and/or rotors.
BACKGROUND
Managing the aural characteristics (the combination of the all of the acoustically
radiating sources) of an aircraft is important in many environments. Minimizing annoyance to
passengers and people on the ground (known as noise pollution) is important to civil
applications, while avoiding detection is important to military aircraft utility. Indeed, noise
pollution, and the desire to control (or reduce) it, has resulted in significant regulation preventing
or otherwise inhibiting, operation of aircraft in close proximity to people and/or residential areas.
Furthermore, this acoustic radiation has significant directionality and can propagate long
distances. Beyond nuisance, high-intensity noise produced in certain applications can pose a
health risk and can even pose a risk to nearby materials’ structural integrity.
Rotor-driven aircraft are particularly prone to generate acoustic radiation, where
the aircraft’s rotors/propellers are a dominant source of acoustic radiation. Accordingly, acoustic
radiation emitted by propellers/fans/rotors is an undesirable byproduct of their primary function
– to generate thrust/propulsion.
Any discussion of documents, acts, materials, devices, articles or the like which
has been included in the present disclosure is not to be taken as an admission that any or all of
these matters form part of the prior art base or were common general knowledge in the field
relevant to the present disclosure as it existed before the priority date of each claim of this
application.
SUMMARY OF THE INVENTION
The present invention is directed to a system and method for controlling the
acoustic radiation emitted by aircraft.
According to a first aspect, a system for controlling acoustic radiation in an
aircraft comprises: one or more rotor systems, each of the one or more rotor systems having a
rotor, a motor to rotate the rotor, and a rotor controller to control the operation of the motor,
wherein, upon receipt of a commanded flight setting from a flight control system, the one or
more rotor systems are configured to generate, individually and in aggregate, desired acoustic
radiation having a first acoustic behavior; and a noise controller operatively coupled with the
flight control system and each of the one or more rotor systems to regulate acoustic radiation
from the one or more rotor systems, wherein the noise controller is configured to regulate the
commanded flight setting from the flight control system and to output a regulated flight setting to
the one or more rotor systems, and wherein, upon receipt of the regulated flight setting from the
noise controller, the one or more rotor systems are configured to generate, individually and in
aggregate, acoustic radiation having a second acoustic behavior that is different from the first
acoustic behavior.
According to a second aspect, a system for controlling acoustic radiation
comprises: one or more rotor systems, each of the one or more rotor systems having a rotor, a
motor to rotate the rotor, and a rotor controller to control an operation of the motor; and a noise
controller operatively coupled with a flight control system and each of the one or more rotor
systems to regulate acoustic radiation from the one or more rotor systems, wherein the noise
controller is configured to receive a commanded flight setting from the flight control system and
to output a regulated flight setting to the one or more rotor systems to regulate the acoustic
radiation from the one or more rotor systems to comply with a target acoustic behavior.
In certain aspects, the noise controller is configured to employ one or more
beamforming techniques to adjust directionality of the acoustic radiation to comply with the
target acoustic behavior.
In certain aspects, the noise controller is configured to provide feedback to a
control interface reflecting present and future performance of the system.
In certain aspects, the noise controller regulates the commanded flight setting
based at least in part on noise configuration data from a noise control interface coupled to the
noise controller.
In certain aspects, the system further comprises one or more input modules,
wherein the noise controller regulates the commanded flight setting based at least in part on
operating parameter data from said one or more input modules.
In certain aspects, the noise configuration data specifies a target acoustic
behavior.
In certain aspects, the noise controller compares the second acoustic behavior
with the target acoustic behavior to determine whether the second acoustic behavior complies
with the target acoustic behavior.
In certain aspects, the noise controller employs beamforming techniques to adjust
directionality of the acoustic radiation from the one or more rotor systems.
In certain aspects, directionality of acoustic radiation from the one or more rotor
systems is controlled by regulating the frequency content and phase of each rotor within the one
or more rotor systems.
In certain aspects, the noise controller is configured to control thrust from each
rotor within the one or more rotor systems by regulating each rotor’s blade pitch.
In certain aspects, each of the one or more rotor systems includes a rotor feedback
device to provide feedback to the noise controller.
In certain aspects, the noise controller is configured to communicate the feedback
from each rotor feedback device to the flight control system.
In certain aspects, the operating parameter data includes at least one of: (1) flight
setting adjustment limits; (2) one or more models for the rotor controller; and (3) aircraft
configuration.
According to a third aspect, a method for controlling acoustic radiation in an
aircraft having a one or more rotor systems comprises: receiving, at a noise controller, a
commanded flight setting from a flight control system; receiving, from a noise control interface,
noise configuration data, wherein the noise configuration data specifies a target acoustic
behavior for the one or more rotor systems; regulating the commanded flight setting to generate a
regulated flight setting, wherein the regulated flight setting is generated based at least in part on
the noise configuration data; and communicating the regulated flight setting to at least one of the
one or more rotor systems.
In certain aspects, the method further comprises the step of determining an
acoustic behavior for the one or more rotor systems generated in response to the regulated flight
setting.
In certain aspects, the method further comprises the step of comparing the
acoustic behavior generated in response to the regulated flight setting with the target acoustic
behavior.
In certain aspects, the method further comprises the step of regulating the
regulated flight setting if the acoustic behavior does not comply with the target acoustic
behavior.
In certain aspects, the regulated flight setting employs beamforming techniques to
change the directionality of acoustic radiation from the one or more rotor systems.
In certain aspects, the regulated flight setting regulates the frequency content and
phase of each motor within the one or more rotor systems to change the directionality of acoustic
radiation from the one or more rotor systems.
In certain aspects, the method further comprises the step receiving, from one or
more input modules, operating parameter data, wherein the regulated flight setting is generated
based at least in part on the operating parameter data.
In certain aspects, the operating parameter data includes at least one of: (1) flight
setting adjustment limits; (2) one or more models for the rotor controller; and (3) aircraft
configuration.
In certain aspects, the method further comprises the step of tuning each motor
within the one or more rotor systems to distribute the acoustic energy across a range of
frequencies as possible or otherwise optimize the acoustic character of each motor to reduce
detectability and/or annoyance.
An embodiment of the invention involves a system for controlling acoustic
radiation in an aircraft, the system includes one or more rotor systems, each of the one or more
rotor systems having a rotor, a motor to rotate the rotor, and a rotor controller to control the
operation of the motor, wherein, upon receipt of a commanded flight setting from a flight control
system, the one or more rotor systems are configured to generate, individually and in aggregate,
desired acoustic radiation having a first acoustic behavior; and a noise controller operatively
coupled with the flight control system and each of the one or more rotor systems to regulate
acoustic radiation from the one or more rotor systems, wherein the noise controller is configured
to regulate the commanded flight setting from the flight control system and to output a regulated
flight setting to the one or more rotor systems, and wherein, upon receipt of the regulated flight
setting from the noise controller, the one or more rotor systems are configured to generate,
individually and in aggregate, acoustic radiation having a second acoustic behavior that is
different from the first acoustic behavior. The noise controller may be configured to regulate the
commanded flight setting based at least in part on noise configuration data from a noise control
interface coupled to the noise controller. This can enhance operation. The system may also
include one or more input modules, wherein the noise controller is configured to regulate the
commanded flight setting based at least in part on operating parameter data from said one or
more input modules. The noise configuration data may specify a target acoustic behavior. The
noise controller may be configured to compare the second acoustic behavior with the target
acoustic behavior to determine whether the second acoustic behavior complies with the target
acoustic behavior. The noise controller may be configured to employ beamforming techniques
to adjust directionality of the acoustic radiation from the one or more rotor systems.
Directionality of acoustic radiation from the one or more rotor systems may be controlled by
regulating the frequency content and phase of each rotor within the one or more rotor systems.
The noise controller may be configured to control thrust from each rotor within the one or more
rotor systems by regulating each rotor’s blade pitch. At least one of the one or more rotor
systems may include a rotor feedback device to provide feedback to the noise controller. The
noise controller may be configured to communicate the feedback from each rotor feedback
device to the flight control system. The operating parameter data may include at least one of:
(1) flight setting adjustment limits; (2) one or more models for the rotor controller; and (3)
aircraft configuration.
Another embodiment of the invention involves a method for controlling acoustic
radiation in an aircraft having a one or more rotor systems, the method includes receiving, at a
noise controller, a commanded flight setting from a flight control system; receiving, from a noise
control interface, noise configuration data, wherein the noise configuration data is configured to
specify a target acoustic behavior for the one or more rotor systems; regulating the commanded
flight setting to generate a regulated flight setting, wherein the regulated flight setting is
generated based at least in part on the noise configuration data; and communicating the regulated
flight setting to at least one of the one or more rotor systems. The method may also include the
step of determining an acoustic behavior for the one or more rotor systems generated in response
to the regulated flight setting. The method may also include the step of comparing the acoustic
behavior generated in response to the regulated flight setting with the target acoustic behavior.
The method may also include the step of regulating the regulated flight setting if the acoustic
behavior does not comply with the target acoustic behavior. The regulated flight setting may be
configured to employ beamforming techniques to change the directionality of acoustic radiation
from the one or more rotor systems. The regulated flight setting may be configured to regulate
the frequency content and phase of each motor within the one or more rotor systems to change
the directionality of acoustic radiation from the one or more rotor systems. The method may
also include the step receiving, from one or more input modules, operating parameter data,
wherein the regulated flight setting is generated based at least in part on the operating parameter
data. The operating parameter data may include at least one of: (1) flight setting
adjustment limits; (2) one or more models for the rotor controller; and (3) aircraft configuration.
The method may also include the step of tuning each motor within the one or more rotor systems
to distribute the acoustic energy across a range of frequencies as possible or otherwise optimize
the acoustic character of each motor to reduce detectability and/or annoyance.
Another embodiment of the invention involves a system for controlling acoustic
radiation, the system that includes one or more rotor systems, each of the one or more rotor
systems having a rotor, a motor to rotate the rotor, and a rotor controller to control an operation
of the motor; and a noise controller operatively coupled with a flight control system and each of
the one or more rotor systems to regulate acoustic radiation from the one or more rotor systems,
wherein the noise controller is configured to receive a commanded flight setting from the flight
control system and to output a regulated flight setting to the one or more rotor systems to
regulate the acoustic radiation from the one or more rotor systems to comply with a target
acoustic behavior. The noise controller may be configured to employ one or more beamforming
techniques to adjust directionality of the acoustic radiation to comply with the target acoustic
behavior. This will enhance operation. The noise controller may be configured to provide
feedback to a control interface reflecting present and future performance of the system.
DESCRIPTION OF THE DRAWINGS
These and other advantages of the present invention will be readily understood
with the reference to the following specifications and attached drawings wherein:
Figure 1 illustrates an architecture of an example acoustic radiation control
system.
Figures 2a through 2c illustrate acoustic radiation patterns emitted by an example
fixed wing aircraft vis-à-vis a distant observer.
Figure 3 illustrates a second example aircraft suitable for use with an acoustic
radiation control system.
Figure 4 illustrates an exemplary acoustic radiation control process for an acoustic
radiation control system.
Figure 5 illustrates a functional diagram for a flight control system embodying an
acoustic radiation control process.
DETAILED DESCRIPTION
Preferred embodiments of the present invention will be described hereinbelow
with reference to the accompanying drawings. The components in the drawings are not
necessarily drawn to scale, the emphasis instead being placed upon clearly illustrating the
principles of the present embodiments. For instance, the size of an element may be exaggerated
for clarity and convenience of description. Moreover, wherever possible, the same reference
numbers are used throughout the drawings to refer to the same or like elements of an
embodiment. In the following description, well-known functions or constructions are not
described in detail because they may obscure the invention in unnecessary detail. No language in
the specification should be construed as indicating any unclaimed element as essential to the
practice of the embodiments. In the following description, it is understood that terms such as
“first,” “second,” “top,” “bottom,” “side,” “front,” “back,” and the like, are words of
convenience and are not to be construed as limiting terms. For this application, the following
terms and definitions shall apply:
As used herein, the words “about” and “approximately,” when used to modify or
describe a value (or range of values), mean reasonably close to that value or range of values.
Thus, the embodiments described herein are not limited to only the recited values and ranges of
values, but rather should include reasonably workable deviations. The terms horizontal and
vertical, as used herein, are used to describe angles or planes relative to the ground, such as when
the aircraft is on the ground.
As used herein, the terms “aerial vehicle” and “aircraft” refer to a machine
capable of flight, including, but not limited to, fixed-wing aircraft, unmanned aerial vehicle,
variable wing aircraft, and vertical take-off and landing (VTOL) aircraft. VTOL aircraft may
include fixed-wing aircraft (e.g., Harrier jets), rotorcraft (e.g., helicopters), tilt-rotor/tilt-wing
aircraft, multi-rotor aircraft, etc.
As utilized herein, “and/or” means any one or more of the items in the list joined
by “and/or”. As an example, “x and/or y” means any element of the three-element set {(x), (y),
(x, y)}. In other words, “x and/or y” means “one or both of x and y”. As another example, “x, y,
and/or z” means any element of the seven-element set {(x), (y), (z), (x, y), (x, z), (y, z), (x, y, z)}.
In other words, “x, y, and/or z” means “one or more of x, y, and z.”
As used herein, the terms “communicate” and “communicating” refer to both
transmitting, or otherwise conveying, data from a source to a destination and delivering data to a
communications medium, system, channel, network, device, wire, cable, fiber, circuit, and/or
link to be conveyed to a destination.
As used herein, the terms “circuits” and “circuitry” refer to physical electronic
components (i.e., hardware) and any software and/or firmware (“code”) which may configure the
hardware, be executed by the hardware, and or otherwise be associated with the hardware. As
used herein, for example, a particular processor and memory may comprise a first “circuit” when
executing a first set of one or more lines of code and may comprise a second “circuit” when
executing a second set of one or more lines of code.
As used herein, the term “exemplary” means serving as a non-limiting example,
instance, or illustration. As utilized herein, the terms “e.g.” and “for example” set off lists of one
or more non-limiting examples, instances, or illustrations. As utilized herein, circuitry is
“operable” to perform a function whenever the circuitry comprises the necessary hardware and
code (if any is necessary) to perform the function, regardless of whether performance of the
function is disabled or not enabled (e.g., by an operator-configurable setting, factory trim, etc.).
As used herein, the term “processor” means processing devices, apparatuses,
programs, circuits, components, systems, and subsystems, whether implemented in hardware,
tangibly embodied software, or both, and whether or not it is programmable. The term
“processor” as used herein includes, but is not limited to, one or more computing devices,
hardwired circuits, signal-modifying devices and systems, devices and machines for controlling
systems, central processing units, programmable devices and systems, field-programmable gate
arrays, application-specific integrated circuits, systems on a chip, systems comprising discrete
elements and/or circuits, state machines, virtual machines, data processors, processing facilities,
and combinations of any of the foregoing. The processor may be, for example, any type of
general purpose microprocessor or microcontroller, a digital signal processing (DSP) processor,
an application-specific integrated circuit (ASIC). The processor may be coupled to, or integrated
with a memory device.
As used herein, the term “memory device” means computer hardware or circuitry
to store information for use by a processor. The memory device can be any suitable type of
computer memory or any other type of electronic storage medium, such as, for example, read-
only memory (ROM), random access memory (RAM), cache memory, compact disc read-only
memory (CDROM), electro-optical memory, magneto-optical memory, programmable read-only
memory (PROM), erasable programmable read-only memory (EPROM), electrically-erasable
programmable read-only memory (EEPROM), a computer-readable medium, or the like.
As used herein, the term “rotor” means a device having a central hub with one or
more radiating blades to convert rotary motion to produce thrust and/or a propulsive force.
Example rotors include, without limitation, aircraft propellers, fans, integrally bladed rotors
(IBR), bladed disks (e.g., blisks), and helicopter rotors.
Throughout this specification the word “comprise”, or variations such as
“comprises” or “comprising”, will be understood to imply the inclusion of a stated element,
integer or step, or group of elements, integers or steps, but not the exclusion of any other
element, integer or step, or group of elements, integers or steps.
Disclosed herein is a system and method for controlling acoustic radiation emitted
by an aircraft, including the aircraft’s rotor assembly (e.g., a propeller, or other rotor, driven by a
mechanical device). While existing solutions attempt to mitigate acoustic radiation through the
design of quiet rotor blades, quiet motors, etc., these existing solutions do not address the
acoustic radiation sources as a collective, which can be managed as a whole to yield more
effective results. There are tunings that can be applied in real-time to the operation of the one or
more rotors to make the radiated energy less perceptible and/or less annoying to an acoustic area
of interest (e.g., persons on the ground), however they do not address the acoustic radiation
sources as a collective either.
The disclosed acoustic radiation control system offers a number of advantages
over existing solutions for controlling acoustic radiation, which traditionally sustain significant
performance and/or operational penalties. For example, one solution for controlling acoustic
radiation is to reduce thrust by controlling rotational speed and/or disk loading, thus reducing
acoustic radiation. Another solution for controlling acoustic radiation requires narrowly defined
flight profiles. The acoustic radiation control system disclosed herein, however, manages
aggregate noise from one or more of rotor systems as a collective set using a central noise
controller (i.e., managing the noise sources together). The noise controller can therefore alter the
aggregate acoustic radiation of the aircraft in ways that were not previously possible when the
noise sources are allowed to operate independently of one another. Integrating the acoustic
radiation control system into an aircraft’s propulsion control system makes it possible to tailor
the acoustic radiation produced from one or more rotors, for example, controlling perceptibility
and/or annoyance to an acoustic area of interest without critically compromising the rotor’s
primary role of sustaining flight.
Figure 1 illustrates an architecture of an example acoustic radiation control
system 100 employed in an aircraft (e.g., fixed wing aircraft 202, multi-rotor aerial vehicle 300).
As can be appreciated, however, the components of the acoustic radiation control system 100
may be varied across the different types of aircraft configurations (e.g., turbo-prop, all electric,
hybrid electric), but the underlying principles of the acoustic radiation control system 100 remain
applicable, regardless of the aircraft configuration and type of rotor assembly 128.
As illustrated, the acoustic radiation control system 100 may comprise a central
noise controller 102, a noise control interface 104, a flight control system 106, a flight control
system interface 108, a plurality of input modules 122, and a plurality of rotor systems 126. Each
of the plurality of rotor systems 126 may include a rotor assembly 128 (e.g., a combination of a
rotor 120 and a mechanical device 124 to rotate the rotor 120), a rotor controller 116, and/or a
rotor feedback device 118. The plurality of input modules 122 may include, for example, an
allowed deviation module 110, a rotor driver module 112, and an aircraft layout module 114.
The noise controller 102 couples (e.g., monitors and controls) the plurality of
rotor systems 126 to create a radiating array. In operation, the radiating array can dynamically
(e.g., continuously in real-time or near real-time) set one or more of the control parameters for
each rotor assembly 128. The control parameters may include, for example, revolutions per
minute (RPM), blade pitch, and phase for each mechanical device 124 (e.g., an electric motor).
The control parameters may be selected by the noise controller 102 such that the rotor systems
126 operate within acceptable operating ranges, which can be specified by a primary function set
point (e.g., desired thrust setting). The acoustic radiation control system 100 may use high
bandwidth, fast response motor controllers. Each rotor system 126 may provide, as feedback,
precise motor state information (e.g., via a rotor controller 116 and/or a rotor feedback device
118), which may be facilitated using, for example, high-precision rotation position encoders.
Noise Management Components. The primary noise management components
include a noise controller 102 communicatively coupled with a noise control interface 104. The
noise control interface 104 enables a high-level operator (e.g., an autopilot, human pilot, etc.) to
interface, or otherwise communicate, with the noise controller 102 to facilitate noise
management. For example, the noise control interface 104 may enable the high-level operator to
input a desired noise configuration (or otherwise regulate the noise profile) to generate noise
configuration data that may be passed to the noise controller for processing.
The noise control interface 104 may be an interface to communicate with another
system (e.g., autopilot), or include one or more user-actuated input devices for use by a human
operator. The one or more user-actuated input devices may include, for example, physical
buttons, physical switches, a digitizer (whether a touch pad, or transparent layer overlaying a
display device), and other input devices. The noise control interface 104 may further include one
or more display devices, such as one or more light emitting diodes (LEDs), liquid crystal display
(LCD) screens, speakers, alarms, etc. The one or more user-actuated input devices may be local
(i.e., on the aircraft) or remote (e.g., off the aircraft and communicatively coupled via a network,
such as wireless communication). The noise control interface 104 may provide feedback
information on how the commanded flight behaviors impact the acoustic signature of the aircraft
(e.g., pitching up may project more acoustic energy forward, rapid throttle changes will be more
noticeable), possibly including indication of performance metrics with regard to achieving a
desired acoustic signature and how aircraft maneuvering impacts the metrics (e.g., experienced
perceived noise level (EPNL)) or violates thresholds (e.g., operating requirements over a
residential area require do not exceed n dB). This feedback may be provided in real-time or
forward predicted to facilitate flight planning or operation (e.g., staying on this descent profile
will violate the desired perception threshold in n seconds). This feedback many be utilized by a
human or an autonomous controller to plan, execute, and/or monitor the acoustic performance of
the aircraft. As one example, the feedback may be provided in a form useful to a route planning
routine to balance the acoustic impact of a route against other cost parameters (e.g., fuel burn,
flight time, etc.).
The noise control interface 104 may be integrated with (or incorporate therein),
for example, a geographic information system (GIS). The GIS may be used to automatically
determine a desired acoustic management technique for a given location and flight operation
based, at least in part, on geographic conditions, structures, population distributions, other GIS
data. To that end, the GIS may be employed to capture, store, check, and/or display data related
to the geography of Earth’s surface. The GIS may further display and/or provide map data to
enable the noise controller 102 to comprehend and analyze geographic features of the Earth’s
surface.
The noise controller 102 includes one or more processors operatively coupled
with at least one memory device to execute the one or more noise control processes and/or
algorithms stored to the memory device(s). The noise controller 102 is communicatively coupled
between the flight control system 106 and a plurality of rotor systems 126. In operation, the noise
controller 102 receives and regulates (e.g., modifies) one or more commanded flight settings
(e.g., rotor assembly commands and/or navigational commands) from the flight control system
106.
The one or more commanded flight settings are regulated by the noise controller
102 to yield one or more one or more regulated flight settings, which may then be passed to each
of the plurality of rotor systems 126. For example, the noise controller 102 may determine (e.g.,
through modeling and/or actual measurements) that the commanded flight settings may, when
communicated to the plurality of rotor systems 126, yield an acoustic behavior that differs from a
target acoustic behavior identified via the noise control interface 104. To achieve the target
acoustic behavior, the regulated flight settings are communicated to the plurality of rotor systems
126 to adjust the aggregate acoustic behavior.
The noise controller 102 may further monitor one or more parameters of each of
the rotor systems 126 using a rotor feedback device 118 at each rotor system 126. The noise
controller 102 communicates the one or more parameters as a rotor/propeller position data-
stream from the rotor system 126 back to the flight control system 106.
The mechanical devices 124 can be further tuned to distribute the acoustic energy
into as wide a range of frequencies as possible, which can be accomplished by selecting different
RPM settings for each mechanical device 124 and/or varying the RPM settings rapidly over time.
This spreading of energy inhibits constructive interference and otherwise reduces the prominence
of tones or other attributes that may be easily perceived or regarded as annoying.
The noise modification schemes applied by the noise controller 102 are designed
to incorporate operating parameter data from one or more of a plurality of input modules 122.
The operating parameter data may reflect operating information and/or parameters (i.e.,
operating limits). The operating information and/or parameters may include, for example, a
desired noise modification scheme, one or more parameters of the particular noise modification
scheme (e.g., a beam direction when beamforming is employed), flight setting adjustment limits
(e.g., from an allowed deviation module 110), one or more models for the rotor controller 116
(e.g., from the rotor driver module 112), aircraft configuration data (e.g., from the aircraft layout
module 114), etc.
The noise controller 102 utilizes the noise configuration data and the operating
parameter data, as well any internally structured schemes, to determine how to regulate the
commanded flight settings from the flight control system 106 to achieve a targeted acoustic
behavior or otherwise comply with the targeted acoustic behavior (i.e., within an predetermined
acceptable deviation from the targeted acoustic behavior). The noise controller 102 may further
communicate status information (e.g., feedback data) to the noise control interface 104 or the
flight control system 106. The status information may include information and/or feedback on
the current state of the noise control scheme. The status information may further include noise
modifications that the noise controller 102 can produce given the limits of a particular
implementation (e.g., based on aircraft configuration).
Input Modules 122. As noted above, the noise controller 102 may be
communicatively coupled with a plurality of input modules 122, such as an allowed deviation
module 110, a rotor driver module 112, and an aircraft layout module 114. Each of the plurality
of input modules 122 may employ any combination of hardware, firmware, and software that is
capable of performing the function associated with the respective module, including, without
limitation, a processor (or other circuitry) coupled to a memory device. The operating parameter
data from the plurality of input modules 122 is used by the noise controller 102 to limit and/or
direct how the commanded flight settings are regulated, or otherwise altered.
The allowed deviation module 110 may be configured to impose a set of system
limits (e.g., permissible variances) to restrict the degree by which the noise controller 102 can
alter the commanded flight settings from the flight control system 106 without compromising
flight characteristics or safety of the aircraft. The system limits may be provided in any number
of ways (e.g., ranges, acceptable percentage deviations) which may change in real-time
throughout the flight. These limits will likely have complex relationships with different flight
phases, weather conditions, etc. For example, the allowed deviation module 110 may indicate
that the aircraft is taking off at its maximum (or near maximum) gross takeoff weight and,
therefore, will require all available thrust to achieve liftoff. Conversely, during descent, the
allowed deviation module 110 may indicate that the rotor assemblies 128 may be throttled down
to an idle speed or a near idle speed.
The allowed deviation module 110 may further impose the set of system limits
based at least in part on weather conditions (e.g., cloud cover). For example, when operating at
or above clouds, the rotor assemblies 128 may not need to be tightly controlled for noise because
clouds can dissipate and/or reflect sound. Therefore, when operating above clouds, an aircraft
can be louder because the clouds can dissipate or deflect the sound upward (away from the
ground). However, when operating just below clouds, an aircraft should be more tightly
controlled for noise (e.g., particularly quiet) because the clouds can deflect the sound downward
(toward the ground and the acoustic area of interest).
The rotor driver module 112 may employ a dynamic model of the rotor controller
116 to provide the noise controller 102 with an understanding of the limits of the rotor controller
116 (e.g., step response time) that will influence the performance of various noise control
schemes. For example, a gas turbine cannot quickly change RPM, therefore an acoustic control
scheme based on fast RPM modulation may not be useful for aircraft that use a gas turbine as the
mechanical device 124.
The aircraft layout module 114 is configured to provide a set of configuration data
describing the configuration of the aircraft and/or the rotor system 126. For example, the
configuration data may describe the rotor system 126 placement/layout in space, propeller/rotor
blade characteristics, fuselage layout, etc. The configuration data may further describe any
aircraft components that are major influencers on the sound propagation (e.g., fuselage). These
various attributes may be used by the noise controller 102 to calculate acoustic propagation and
interference (e.g., calculating the needed phase delays to achieve beamforming may be
accomplished using the relative locations of the noise sources vis-à-vis an acoustic area of
interest using is a trigonometry). This information may be combined with directivity models of
the sources to determine the acoustic behavior.
Rotor System 126. The acoustic radiation control system 100 includes a plurality
of rotor systems 126 coupled to the noise controller 102. Each rotor system 126 may include a
rotor controller 116, a rotor feedback device 118, and a rotor assembly 128 (e.g., a rotor 120 and
a mechanical device 124 to rotate the rotor 120). The mechanical device 124 may be an electric
motor, such as DC-brushless motor, although other mechanical devices 124 are contemplated,
such as gas turbine engines, piston engines, etc.
The rotors 120 may be arranged in various configurations and with one or more
blades (e.g., 1 to 25 or more blades, more preferably 2 to 20 blades, even more preferably 2 to 10
blades, and most preferable 2 to 6 blades). The one or more rotor blades may be adjustable in
terms of blade pitch or other parameters (e.g., integrated flap, deicing bladder, etc.). The blade
pitch may be controlled, for example, by a swashplate connected to the flight control system 106
and/or the noise controller 102. In certain aspects, the rotors 120 may employ a single rotor blade
with a counterweight to provide balance. Further, the one or more rotor blades may be designed
to be inherently low noise.
The acoustic radiation control system 100 is not restricted to a predetermined
number of rotor systems 126. To that end, the acoustic radiation control system 100 is illustrated
th th
as having first, second, and n rotor systems 126, where rotor n 120n represents the n rotor on
the aircraft. The acoustic radiation control system 100 is flexible in that it does not require that
the rotors 120 or the rotor system 126 be aligned in any particular plane or other configuration.
In operation, the rotor controller 116 controls the mechanical device 124 and/or
the rotor 120. The rotor controller 116 may control, for example, the speed of the rotor 120 (e.g.,
the RPM) by controlling current (or throttle/fuel flow) to the mechanical device 124. The rotor
controller 116 can also control or adjust the blade pitch, shaft position, current draw, thrust,
phase for each electric motor, etc. For example, where the mechanical device 124 is an electric
motor, the rotor controller 116 may control the electric motor by adjusting the operating current
to the electric motor via a current controller in response to, for example, a flight setting
command from the noise controller 102 and/or the flight control system 106.
The rotor feedback device 118 uses one or more sensors to monitor dynamically
one or more parameters of the rotor assembly 128. The one or more parameters may include, for
example, blade pitch, shaft position, RPM, noise level, current draw, thrust, phase for each
electric motor, etc. The one or more parameters may be dynamically communicated to the noise
controller 102 by the rotor feedback device 118 as a data-stream of rotor parameter data.
The mechanical devices 124 can be tuned such that they each produce the same
set of frequencies. In the case of an aircraft with varying rotor 120 radii, for example, different
RPMs and/or blade pitches may be selected by the noise controller 102 to achieve the desired
acoustic frequency content and thrust performance.
Flight Control Components. The flight control components include a flight
control interface 108 and the flight control system 106. The flight control interface 108 provides
for communication of aircraft flight characteristics between a high-level operator (e.g., an
autopilot, human pilot, etc.) and low-level flight control system to provide flight commands of
the desired aircraft behavior (e.g., commanded flight settings). The commanded flight settings
may include rotor assembly commands and/or navigational commands, such as a target waypoint
location, rotor speed/RPM, blade pitch, etc. The flight control interface 108 may include one or
more user-actuated input devices, such as physical buttons, physical switches, a digitizer
(whether a touch pad, or transparent layer overlaying a display device), and other input devices.
The flight control interface 108 may further include one or more display devices, such as one or
more LEDs, LCD screens, speakers, alarms, etc.
The flight control interface 108 may be operatively coupled with one or more
cockpit controls, such as primary flight controls (stick/yoke, stick, side-stick or collective, rudder
pedals, brakes, and throttles) and the secondary flight controls (e.g., switches, knobs, rockers,
fuses, etc.). The cockpit controls may be local (i.e., on the aircraft) or remote (e.g., off the
aircraft and communicatively coupled via a network, such as wireless communication).
The flight control system 106 is communicatively coupled with the noise
controller 102. The flight control system 106 is configured to translate the commanded behaviors
from the operator into one or more commanded flight settings reflecting individual control
effector commands for the aircraft, such as control surfaces, setting for the rotor assembly 128.
In a traditional system, commands from the flight control system 106 would be directly linked to
the rotor controller 116. When using an acoustic radiation control system 100, however, the
flight control system 106 instead passes the one or more commanded flight settings (e.g., original
commanded flight settings) to the noise controller 102, which can relay and/or modify the one or
more commanded flight settings (e.g., as adjusted commanded flight settings) to the rotor system
126. It is contemplated, however, that the functionality of the acoustic radiation control system
100 may be integrated with the flight control system 106 as a single system.
The flight control system 106 may include, or communicate with, existing flight
control devices or systems, such as those used in fixed-wing aircraft and rotary-wing aircraft. To
that end, a communication system may be provided to enable the flight control system 106 to
communicate with other devices (including remote or distant devices) via, for example, a
network. The communication system may receive communication commands and configuration
data from the flight control interface 108, while sending status and response information from
the communication system to the flight control interface 108.
Other Aircraft System Components. The noise controller 102 and/or the flight
control system 106 may also be communicatively coupled with an onboard data storage device
(e.g., hard drive, flash memory, or the like), a wireless communication device, or virtually any
other desired service(s). The noise controller 102 and/or the flight control system 106 may
further be communicatively coupled with navigational devices, such as an inertial navigation
system (“INS”) communicatively coupled with an inertial measurement unit (“IMU”) and/or a
global positioning system (“GPS”) receiver). The GPS gives an absolute drift-free position value
that can be used to reset the INS solution or can be blended with it by use of a mathematical
algorithm, such as a Kalman Filter. The flight control system 106 may further be coupled with an
intelligence, surveillance, and reconnaissance (“ISR”) surveillance payload, which may be used
to collect data, monitor an area, and/or provide feedback to the flight control system 106. For
example, the aircraft may be equipped with one or more cameras, audio devices, and other
sensors. Any video, or other data, collected by the aircraft may be communicated to a ground
control station in real-time, wirelessly. The aircraft may be further equipped to store said video
and data to the onboard data storage device.
Noise Modification Schemes. The noise controller 102 can employ one or more
of a plurality of noise modification schemes (and other noise-quality improvement techniques) to
generate the regulated flight settings and/or to achieve a target acoustic behavior. A few example
noise modification schemes include, for example, beamforming, spectral tone spreading, tailored
throttle change profiles, or exploitation of frequency masking.
By way of example, the noise controller 102 may employ beamforming
techniques to cancel the noise and/or direct the noise toward (or away from) a specific area (e.g.,
an acoustic area of interest). To initiate the beamforming, an operator may input a command
(e.g., a beam direction, such as 45 degrees azimuthal) to the noise controller 102 (via the noise
control interface 104). In response, the noise controller 102 may modify the noise profile of the
aircraft to achieve an acoustic behavior that directs the noise toward (or away from) a
predetermined location (e.g., complying with a target acoustic behavior). The beam direction
may also be automatically determined by the noise controller 102 based on geography data from
the GIS or images captured by the ISR. For example, the GIS may identify a specific
geographical region has having a dense population. Using the geographic data, beamforming
techniques may be employed to automatically and/or dynamically modify the noise to have an
acoustic behavior to avoid the specific geographic region.
To illustrate, Figures 2a through 2c depict the acoustic radiation patterns 204
emitted by an example fixed wing aircraft 202 with two wing-mounted rotor assemblies 128.
Specifically, Figure 2a illustrates a top plan view 200a of the acoustic radiation patterns 204 of a
fixed wing aircraft 202 at a predetermined altitude (A) vis-à-vis a distant acoustic area of
interest, while Figures 2b and 2c illustrate, respectively, a front elevational view 200b and a side
elevational view 200c.
The example acoustic area of interest is an observer 206 located at: (1) a
longitudinal distance (D ) forward of the two wing-mounted rotor assemblies 128a, 128b; (2)
Long
a first lateral distance (D ) from the port-side rotor assembly 128a and a second lateral
Lat_1
distance (D ) from the starboard-side rotor assembly 128b; and (3) a vertical distance (D )
Lat_2 V
below the fixed wing aircraft 202. At this location, the distance from the observer 206 to the two
acoustic radiation patterns 204 (e.g., from rotor assemblies 128a, 128b), which is identified as
vectors Path and Path , is unequal. Path is greater (longer) than Path because the starboard-side
1 2 2 1
rotor assembly 128b is further away from the observer 206 (i.e., D is greater than D ).
Lat_2 Lat_1
Moreover, the nose end of fuselage 208 may partially shield the observer 206 from the starboard
rotor assembly 128.
The different distances and obstruction(s) each influence the noise experienced by
the observer 206. Using the known location(s) of the acoustic radiation pattern(s) 204 and one or
more observer(s) 206, the noise controller 102 may calculate acoustic propagation and
interference to control noise (whether directed toward or away from the observer) along one or
more vectors (e.g., Path and Path ). For example, the noise controller 102 can calculate the
needed phase delays to achieve desired beamforming vectors using trigonometry (e.g., using the
known distances, e.g., D , D , D , etc.), which may be combined with directivity models of
V Long Lat
the sources to determine the acoustic behavior.
Beamforming allows the acoustic energy to be steered to desirable directions
(e.g., aiming a null, a portion of the acoustic radiation pattern that is very quiet, in the direction
of nearby people). Acoustic beamforming can be accomplished by tuning each of the individual
frequency content and phases of each mechanical device 124 (e.g., an electric motor). For
example, beamforming techniques may control each mechanical device 124 to change the
directionality of the array, thereby defining a pattern of constructive and destructive interference
in the wave front. The various aircraft controllers and systems (e.g., the acoustic radiation control
system 100, or components thereof) may be provided via an electronics module, which may be
integrated with the airframe, such as a fuselage, or provided via a separate housing or pod.
While Figures 2a through 2c illustrate fixed-wing aircraft with two rotor
assemblies 128, the acoustic radiation control system 100 is not limited to a particular aircraft
configuration or number of rotor assemblies. Indeed, the acoustic radiation control system 100 is
aircraft and aircraft configuration agnostic, therefore it may be incorporated into virtually any
aircraft that employs one or more rotor assemblies 128 to generate lift and/or thrust, including,
inter alia, rotor-craft (including helicopters and multi-rotor aerial vehicles), fixed-wing aircraft
(including flying wing aircraft), tilt-rotor aircraft, tilt-wing aircraft, etc. Examples include,
without limitation, Cessna-421, Northrop XB-35, Diamond DA42, etc.
Figure 3 illustrates an example multi-rotor aerial vehicle 300 that may be
configured with an acoustic radiation control system 100. As illustrated, the multi-rotor aerial
vehicle 300 may include an airframe 302, landing gear 304 (e.g., skids or wheeled landing gear),
a plurality of booms 306, and a plurality of rotor assemblies 128. The airframe 302 may be
coupled with a proximal end of each of the plurality of booms 306 such that the distal ends of the
plurality of booms 306 extend radially from the airframe 302 (e.g., when viewed form the top, in
an “X” arrangement, as illustrated). The airframe 302 and the plurality of booms 306 may be
fabricated as a singular unit, or as separate components to be coupled to one another. The distal
end of each of the plurality of booms 306 may be coupled with a rotor assembly 128, each of
which is illustrated as a rotor 120 coupled with a mechanical device 124 to drive/rotate the rotor
120. The mechanical device 124 may be an electric motor controlled via an electronic speed
controller (ESC). While the mechanical devices 124 are illustrated as positioned at the distal end
of the boom 306, the mechanical devices 124 (or a single mechanical device 124) may instead be
positioned in the airframe 302 and configured to drive (rotate) one or more rotors 120 via a
gearbox and/or a driveshaft between the mechanical device 124 and the one or more rotor 120.
While the multi-rotor aerial vehicle 300 is illustrated as having an airframe 302
with four booms 306 (each with a single rotor assembly 128 at the distal end of the boom 306),
one of skill in the art would appreciate that additional, or fewer, booms 306 and/or rotor
assemblies 128 may be employed to achieve a desired function. Further, while each boom 306 is
illustrated as having only a single rotor assembly 128, multiple rotor assemblies 128 may be
provided at the distal end of each boom 306. For example, a cross-member may be positioned at
the distal end of each boom 306 and arranged to space the rotor assemblies 128 from one another
(e.g., perpendicularly to the length of the boom 306) to prevent interference between rotors 120.
The multi-rotor aerial vehicle 300 may be equipped with one or more payload pods 308
comprising one or more cameras, audio devices, and other sensors to provide ISR functionality.
Figure 4 illustrates an exemplary acoustic radiation control process 400 for an
acoustic radiation reduction system 100. While the acoustic radiation control process 400 is
illustrated as having steps 404 through 420, one of skill in the art would appreciate that fewer or
additional steps may be implemented. For example, one or more modes may be omitted from the
acoustic radiation control process 400, or performed separately and/or upon request. Moreover,
the order in which the steps are performed may be adjusted depending on the needs of the
aircraft.
Upon startup at step 402, the acoustic radiation reduction system 100 may be
configured to, via a processor of said noise controller 102, cycle through multiple steps, starting
with step 404. At step 404, the noise controller 102 receives a commanded flight setting from,
for example, the flight control system 106 (e.g., an original commanded flight setting).
At step 406, the noise controller 102 may output the commanded flight setting to
one or more rotor systems 126. For example, the commanded flight setting from the flight
control system 106 may be communicated to a rotor controller 116 of each of the one or more
rotor systems 126.
At step 408, the noise controller 102 receives operating parameter data (e.g.,
operating information and/or parameters) from, for example, from one or more of a plurality of
input modules 122. The operating parameter data may include, for example, a desired noise
modification scheme, parameters of the particular noise modification, a range of flight setting
adjustment limits, one or more models for the rotor controller 116, aircraft configuration, etc.
At step 410, the noise controller 102 determines the acoustic behavior of the noise
generated by the one or more rotor assemblies 128 in response to the commanded flight setting.
In one example, the noise controller 102 may be configured to determine the acoustic behavior at
the one or more rotor systems 126 based at least in part on the commanded flight setting and/or
the operating parameter data.
The noise controller 102 may determine the acoustic signature of the aircraft (e.g.,
the total/aggregate acoustic behavior of all rotor assemblies 128 and other noise sources
associated with the aircraft). Alternatively, the noise controller 102 may be configured to
determine separately the acoustic behavior of each rotor assembly 128 or noise source to
determine the aggregate acoustic behavior of the aircraft.
The noise controller 102 may be configured to measure and/or calculate the
acoustic behavior of the rotor assemblies 128 using one or more sensors. Using sensors ensures
that the aggregate acoustic behavior of the aircraft is based on the rotor assemblies’ 128 actual
response to the commanded flight setting from the flight control system 106 (e.g., via rotor
feedback devices 118). For example, microphones and/or other audio sensors may be provided at
or adjacent/near each of the one or more rotor assemblies 128 to measure the aggregate acoustic
behavior (e.g., a waveform, noise map, etc.) of the aircraft.
Alternatively, the acoustic behavior of the aircraft may be determined using
modeling without actually passing the commanded flight setting to the rotor system 126, in
which case step 406 may be omitted. For example, the aggregate acoustic behavior may be
determined through calculations or a look up table of known acoustic behaviors for various
aircraft configurations vis-à-vis the available/known commanded flight settings.
At step 412, the noise controller 102 determines whether the aggregate acoustic
behavior determined at step 408 complies with a target acoustic behavior or profile (e.g., is
within a predetermined deviation/range of a desired acoustic behavior or profile). The target
acoustic behavior or profile may be a static value (or set/range of values) associated with the
aircraft or dynamically selected and/or updated by the operator. For example, the target acoustic
behavior may be received dynamically by the noise controller 102 from the noise control
interface 104, the flight control system 106, and/or the plurality of input modules 122. If the
aggregate acoustic behavior of the aircraft is not within the target acoustic behavior range, the
process continues to step 414. If the aggregate acoustic behavior of the aircraft is within the
target acoustic behavior range, the process continues to step 416.
At step 414, the noise controller 102 generates (e.g., determines/calculates) a
regulated flight command (e.g., adjusted commanded flight settings) that, when communicated to
the one or more rotor systems 126, is predicted to generate a noise that complies with the target
acoustic behavior range.
At step 416, the noise controller 102 outputs a flight setting (either the
commanded flight setting or the regulated flight setting) to the one or more rotor systems 126
(e.g., via the rotor controller 116). The flight setting communicated at step 414 may be
contingent upon whether the measured acoustic behavior was compliant at step 412. Specifically,
if the measured acoustic behavior was compliant, the commanded flight setting is sent to the one
or more rotor systems 126, otherwise the regulated flight setting from step 414 is sent to the one
or more rotor systems 126.
At step 418, the acoustic radiation reduction system 100 determines whether the
acoustic radiation control process 400 should be concluded (e.g., based on an input from the
noise control interface 104 and/or flight control interface 108). If the acoustic radiation control
process 400 is to be concluded, the process ends at step 420. At step 420, the aircraft may be shut
off or simple resume normal operation based on flight commands from the flight control system
106 without modification by the acoustic radiation reduction system 100. Otherwise, the process
400 returns to step 404, whereby the process repeats for the next commanded flight setting.
Figure 5 illustrates a functional diagram 500 for a flight control system 106
embodied with an acoustic radiation control process, such as the acoustic radiation control
process 400. As can be appreciated, a person of skill in the art may elect to loosely or tightly
integrate the acoustic radiation control process 400 with flight controller processes of the flight
control system 106. That is, the acoustic radiation control process 400 may be placed between
the flight control system 106 and the rotor system(s) 126, or integrated directly into the flight
control system 106.
The flight controller processes can include a state estimation process (e.g., in
response to navigational command inputs 510) and trajectory optimization process (e.g., in
response to flight command input 512). As can be appreciated, the state estimation process may
employ taking multiple sensor inputs and fusing them into a unified estimate of the aircraft’s
position, orientation, and other health/status parameters, while the trajectory optimization
process computes a preferred trajectory for the aircraft based at least in part on knowledge of the
aircraft’s state (e.g., from the state estimation process) and capabilities. The trajectory
optimization process can produce the command outputs to the control surfaces 520 and rotor
system(s) 126 via the output 518.
The navigational command inputs 510 may include, for example, information
(e.g., data representing one or more parameters) from the navigational devices or systems, such
as INS, IMU, GPS, etc., while flight command input 512 includes flight commands received
from the flight control interface 108, such as pilot/autopilot navigational commands.
At element 502, the noise controller 102 can calculate a noise profile and output
the noise parameters for the current state of the aircraft and commanded flight condition of the
aircraft using information (e.g., aircraft state data, GIS data, and feedback data) available from
various data inputs 514. The various data inputs 514 may include, for example, one or more rotor
feedback devices 118, rotor driver module 112, aircraft layout module 114, flight control system
106, etc.
The noise controller 102 may process the information (e.g., via a processor)
available from various data inputs 514 to output noise data, including, for example, a global
noise parameter, a maximum/minimum value, or other informative values about the acoustics of
the aircraft.
At element 504, the noise controller 102 may determine whether the noise data
indicates that the commanded flight setting(s) complies with one or more noise objective inputs
516. The one or more noise objective inputs 516 may be received from the noise control
interface 104.
If the one or more noise objectives are not met at step 504, the process proceeds
to step 506, where one or more of the above-described noise modification schemes (e.g.,
beamforming) are applied to optimize the noise before generating the data outputs and outputting
adjusted commanded flight setting(s) 108a as commanded flight settings 108a to the output 518.
If the noise objective inputs 516 are met by the commanded flight setting(s), the
noise controller 102 outputs the original commanded flight setting(s) as commanded flight
settings 108a to the output 518 without modification and the noise data 508b as feedback. As
illustrated, the output 518 may be communicatively coupled with one or more rotor systems 126
and surface controllers 520 (e.g., airfoil surfaces, such as flaps, rudder, etc.). The output 518 may
further provide feedback dynamically to the noise controller (e.g. via element 502).
While the subject disclosure is described with regard to aircraft applications, the
aircraft is presented as an exemplary platform to demonstrate the acoustic radiation control
system described herein. Indeed, one of skill in the art would appreciated that the underlying
principles may be used in other applications where it is desirable to limited noise generated by a
fan or rotor system, including non-aircraft rotor or fan arrays. Example applications include,
heating, ventilation, and air conditioning (HVAC) systems that use fans for cooling, wind
turbines, cooling systems for electronics, etc.
Although various embodiments have been described with reference to a particular
arrangement of parts, features, and like, these are not intended to exhaust all possible
arrangements or features, and indeed many other embodiments, modifications, and variations
will be ascertainable to those of skill in the art. Thus, it is to be understood that the invention
may therefore be practiced otherwise than as specifically described above. The above-cited
patents and patent publications are hereby incorporated by reference in their entirety.
Claims (15)
1. A system for controlling acoustic radiation in an aircraft, the system comprising: one or more rotor systems, each of the one or more rotor systems having a rotor, a motor to rotate the rotor, and a rotor controller to control the operation of the motor, wherein, upon receipt of a commanded flight setting from a flight control system, the one or more rotor system are configured to generate, individually and in aggregate, desired acoustic radiation having a first acoustic behavior; and a noise controller operatively coupled with the flight control system and each of the one or more rotor system to regulate acoustic radiation from the one or more rotor systems, wherein the noise controller is configured to regulate the commanded flight setting from the flight control system and to output a regulated flight setting to the one or more rotor systems, and wherein, upon receipt of the regulated flight setting from the noise controller, the one or more rotor system are configured to generate, individually and in aggregate, acoustic radiation having a second acoustic behavior that is different from the first acoustic behavior.
2. The system of claim 1, wherein the noise controller is configured to regulate the commanded flight setting based at least in part on noise configuration data from a noise control interface coupled to the noise controller.
3. The system of claim 2, further comprising one or more input modules, wherein the noise controller is configured to regulate the commanded flight setting based at least in part on operating parameter data from said one or more input modules.
4. The system of claim 2 or claim 3, wherein the noise configuration data specifies a target acoustic behavior.
5. The system of claim 4, wherein the noise controller is configured to compare the second acoustic behavior with the target acoustic behavior to determine whether the second acoustic behavior complies with the target acoustic behavior.
6. The system of claim 1, claim 2, claim 3, claim 4 or claim 5 wherein the noise controller (102) is configured to employ beamforming techniques to adjust directionality of the acoustic radiation from the one or more rotor systems.
7. The system of claim 1, claim 2, claim 3, claim 4 claim 5 or claim 6 wherein directionality of acoustic radiation from the one or more rotor system is controlled by regulating the frequency content and phase of each rotor within the one or more rotor systems .
8. The system of claim 1, claim 2, claim 3, claim 4 claim 5, claim 6 or claim 7 wherein the noise controller is configured to control thrust from each rotor within the one or more rotor systems by regulating each rotor’s blade pitch.
9. The system of claim 1, claim 2, claim 3, claim 4 claim 5, claim 6, claim 7 or claim 8 wherein each of the one or more rotor systems includes a rotor feedback device to provide feedback to the noise controller.
10. The system of claim 3, claim 4, claim 5 claim 6, claim 7, claim 8 or claim 9 wherein the operating parameter data includes at least one of: (1) flight setting adjustment limits; (2) one or more models for the rotor controller; and (3) aircraft configuration.
11. A method for controlling acoustic radiation in an aircraft having a one or more rotor systems, the method comprising: receiving, at a noise controller, a commanded flight setting from a flight control system; receiving, from a noise control interface, noise configuration data, wherein the noise configuration data is configured to specify a target acoustic behavior for the one or more rotor systems ; regulating the commanded flight setting to generate a regulated flight setting, wherein the regulated flight setting is generated based at least in part on the noise configuration data; and communicating the regulated flight setting to at least one of the one or more rotor systems.
12. The method of claim 11, further comprising the step of determining an acoustic behavior for the one or more rotor system generated in response to the regulated flight setting.
13. The method of claim 11, or claim 12 wherein the regulated flight setting is configured to employ beamforming techniques to change the directionality of acoustic radiation from the one or more rotor systems.
14. The method of claim 11, claim 12, or claim 13 wherein the regulated flight setting is configured to regulate the frequency content and phase of each motor within the one or more rotor system to change the directionality of acoustic radiation from the one or more rotor systems.
15. The method of claim 11, claim 12, claim 13, or claim 14 further comprising the step receiving, from one or more input modules, operating parameter data, wherein the regulated flight setting is generated based at least in part on the operating parameter data.
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US15/588977 | 2017-05-08 |
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