Environmental conditions associated with the operation of an aircraft may impose stress or strain on the aircraft. For example, a rotor hub associated with a rotorcraft may experience vibratory loads caused by aerodynamic forces on the blades. The blade loads may be summed at the hub and, if not attenuated, may be propagated through the rotor shaft and main transmission into the airframe.
An approach to controlling fuselage vibration has involved the use of hub-mounted passive absorbers tuned to attenuate the dominant rotating system vibration frequency (e.g., 3/rev for a four-bladed rotor) as well as 4/rev active vibration control (AVC) fixed system actuators throughout the fuselage. Many aircraft are equipped with a 3/rev bifilar to suppress some of the in-plane loads as well as fixed system AVC. These configurations only suppress 4/rev vibration and leave other frequencies, such as 2/rev or 8/rev un-attenuated. Some aircraft use two complete AVC systems to be able to attenuate both 2/rev and 4/rev, resulting in added aircraft weight.
An embodiment is directed to a method that includes obtaining, by a controller comprising a processor, data; determining, by the controller, a vibratory load based on the data; and setting, by the controller, an eccentric rotational speed of an actuator at a first frequency and modulating the eccentric rotational speed by a second frequency based on the vibratory load.
Another embodiment is directed to an apparatus having at least one processor; and memory having instructions stored thereon that, when executed by the at least one processor, cause the apparatus to: obtain data, determine a vibratory load based on the data, and set an eccentric rotational speed of an actuator at a first frequency and modulate the eccentric rotational speed by a second frequency based on the vibratory load.
Another embodiment is directed to a system having an actuator configured to reduce the impact of a vibratory load imposed on an airframe of a rotorcraft to an amount that is less than a threshold; and a controller configured to: obtain data, determine the vibratory load based on the data, and set an eccentric rotational speed of an actuator at a first frequency and modulate the eccentric rotational speed by a second frequency based on the vibratory load.
Another embodiment is directed to a system having a motor configured to spin an eccentric mass to provide a force output characterized by a plurality of frequencies associated with an operation of a rotor; and an electronics unit coupled to the motor and configured to determine a desirable position of the mass to obtain the force output.
Additional embodiments are described below.
The present disclosure is illustrated by way of example and not limited in the accompanying figures in which like reference numerals indicate similar elements.
It is noted that various connections are set forth between elements in the following description and in the drawings (the contents of which are included in this disclosure by way of reference). It is noted that these connections in general and, unless specified otherwise, may be direct or indirect and that this specification is not intended to be limiting in this respect. In this respect, a coupling between entities may refer to either a direct or an indirect connection.
Exemplary embodiments of apparatuses, systems, and methods are described for providing active vibration control (AVC). In some embodiments, the AVC may be used to mitigate the impact of two distinct frequencies. Eccentric rotational speed of an AVC actuator may be modulated, such that the actuator produces a controllable force output at the two distinct frequencies.
Referring to
The memory 102 may be configured to store data 106. Data 106 may include data originating from one or more sources. The data 106 may pertain to one or more parameters, such as an eccentric rotational speed, force, torque, etc.
The instructions stored in the memory 102 may be executed by one or more processors, such as a processor 110. The processor 110 may be configured to process the data 106. It is to be understood that the data 106 may be stored on separate media from the programs 104a, 104b.
The processor 110 may be coupled to one or more input/output (I/O) devices 112. In some embodiments, the I/O device(s) 112 may include one or more of a keyboard or keypad, a touchscreen or touch panel, a display screen, a microphone, a speaker, a mouse, a button, a remote control, a joystick, a printer, etc. The I/O device(s) 112 may be configured to provide an interface to allow a user or another entity (e.g., another computing entity) to interact with the system 100. The device 112 may also be configured to transmit or receive sensor data and/or commands to the processor 110.
The system 100 is illustrative. In some embodiments, one or more of the entities may be optional. In some embodiments, additional entities not shown may be included. In some embodiments, the entities may be arranged or organized in a manner different from what is shown in
As illustrated in
The system 202 may include one or more sensors, such as a sensor 206 located on the airframe 204. The sensor 206 may be configured to detect or measure the extent of the vibration caused by the operation and use of the blades 212, potentially as a function of a rotational speed or rotational frequency associated with the main rotor assembly 201. In some embodiments, the sensor 206 may include one or more accelerometers. The sensor 206 may provide data pertaining to the vibration to a controller 208.
The controller 208 may be configured to process the data from the sensor 206. Based on the data processing, the controller 208 may cause one or more commands or directives to be issued to the actuator 210 which acts as an active vibration controller to offset or cancel vibratory loads on the airframe 204. In some embodiments, the commands or directives may serve to modulate an eccentric rotational speed associated with the actuator 210. In exemplary embodiments, the eccentric rotational speed is set at a first frequency. The eccentric rotational speed is modulated by a second frequency to provide a force output at two distinct frequencies.
The actuator 210 may be associated with one or more eccentric masses (not shown). The actuator 210 may be configured to produce one or more outputs that may mitigate (e.g., cancel) the impact or effect of the vibration caused by the main rotor assembly 201 on the airframe 204. For example, the actuator 210 may be configured to control the mass(es) to produce a force that is approximately equal to (e.g., within a threshold of the magnitude of), but opposite in sign from, the forces generated as a result of the operation/vibration associated with the main rotor assembly 201. In some embodiments, the force produced or caused by the actuator 210 may be characterized by two (or more) distinct frequencies, as will be described below in
Referring now to
As shown in
The force generator 252 may be coupled to an electronics unit 260. The electronics unit 260 may provide power to the force generator 252 to control the motor 254. The force generator 252 may provide feedback to the electronics unit 260 regarding the position or location of the eccentric masses 256. The electronics unit 260 may provide directives or commands to the force generator 252 regarding a desired position for the mass 256 in order to realize a damping effect at two or more of the vibration frequencies.
The electronics unit 260 may be coupled to an AVC computer 270. The electronics unit 260 may provide power to the AVC computer 270. The AVC computer 270 may be configured to receive data, such as data pertaining to accelerometer readings or measurements. Based on a processing of the data, the AVC computer 270 may calculate one or more parameters, such as an amplitude, phase, force, or frequency that should be realized by the force generators 252. The AVC computer 270 may provide such parameters to the electronics unit 260, and the electronics unit 260 may process the parameters to determine the desired position for the mass 256 as described above.
The systems 200 and 250 are illustrative. In some embodiments, one or more of the entities may be optional. In some embodiments, additional entities not shown may be included. In some embodiments, the entities may be arranged or organized in a manner different from what is shown in
Turning to
In block 302, data may be obtained from one or more sources. For example, in connection with
In block 304, a determination or calculation may be made regarding the vibratory load imposed on the airframe 204 based on the received sensor data obtained in block 302. The determination/calculation may be made by, e.g., a controller 208.
In block 306, one or more signals representative of commands or directives may be issued by, e.g., a controller 208. The commands/directives may serve to modulate an eccentric rotational speed associated with an actuator 210 at two or more frequencies.
In block 308, the one or more commands of block 306 may be received by, e.g., the actuator 208 as signals.
In block 310, one or more forces may be output by, e.g., the actuator 210. The forces may be based on the received commands of block 308. The forces may be associated with more than one frequency.
The method 300 is illustrative. In some embodiments, one or more of the blocks or operations may be optional. In some embodiments, additional blocks or operations not shown may be included. In some embodiments, the blocks or operations may execute in an order or sequence different from what is shown in
In the example illustrated in
Fz=4 MRω12(1−(|mod(φa,+/−π)|/π)) cos(ω1t+φ1) (1)
Fy=0 (2)
In the example illustrated in
Fz=4 MRω12(1−(|mod(φa,+/−π)|π))cos(ω1t+φ1)+F2cos((ω1+ω2)t+φ2) (3)
Fy=0 (4)
F
2
=g(φb1, φb2,M,R) (5)
In the example illustrated in
Fz=4 MRω12(1−(|mod(φa,+/−π)|/π))cos(ω1+ω2)t+φ2) (6)
Fy=0 (7)
In the example illustrated in
Fz=4 MRω12(1−(|mod(φa,+/−π)|/π)cos(ω1t+φ1)+F2cos((ω1+ω2)t+φ2) (8)
Fy=0 (9)
F
2
=g(φb1, φb2,M,R) (10)
In some embodiments, energy harvesting may be performed. The energy harvesting may be based on a cyclic nature of a given modulation technique and may mitigate any additional power requirements that may be imposed.
Embodiments may be used to produce or generate a controllable force output at two or more frequencies. For example, in connection with the operation of a rotor with four blades, a force output may be generated at a fundamental frequency, which may be 4/rev in this example. The force output may include frequency components at multiples of the fundamental frequency (e.g., 8/rev, 12/rev, 16/rev, etc., in the case of a rotor with four blades). In some embodiments, the force output may include frequency components that are not multiples of the fundamental frequency. For example, integer variations or increments of the fundamental frequency (e.g., 5/rev, 6/rev, 7/rev, etc., in the case of a rotor with four blades) may be included in the force output.
Embodiments have been described in connection with the operation of aircraft or rotorcraft. Aspects of this disclosure may be applied in other contexts. For example, aspects of this disclosure may be used in any environment where vibratory frequencies need to be controlled, such as in the manufacturing of semiconductors.
As described herein, in some embodiments various functions or acts may take place at a given location and/or in connection with the operation of one or more apparatuses, systems, or devices. For example, in some embodiments, a portion of a given function or act may be performed at a first device or location, and the remainder of the function or act may be performed at one or more additional devices or locations.
Embodiments may be implemented using one or more technologies. In some embodiments, an apparatus or system may include one or more processors and memory storing instructions that, when executed by the one or more processors, cause the apparatus or system to perform one or more methodological acts as described herein. Various mechanical components known to those of skill in the art may be used in some embodiments.
Embodiments may be implemented as one or more apparatuses, systems, and/or methods. In some embodiments, instructions may be stored on one or more computer-readable media, such as a transitory and/or non-transitory computer-readable medium. The instructions, when executed, may cause an entity (e.g., an apparatus or system) to perform one or more methodological acts as described herein.
Aspects of the disclosure have been described in terms of illustrative embodiments thereof. Numerous other embodiments, modifications and variations within the scope and spirit of the appended claims will occur to persons of ordinary skill in the art from a review of this disclosure. For example, one of ordinary skill in the art will appreciate that the steps described in conjunction with the illustrative figures may be performed in other than the recited order, and that one or more steps illustrated may be optional.