Abstract:
Embodiments are directed to obtaining data from a plurality of sensors located on a rotorcraft, wherein a first plurality of the sensors is associated with a hub of the rotorcraft and a second plurality of the sensors is associated with blades of the rotorcraft, processing the data to isolate blade dynamics using the data from the sensors associated with the blade from rotorcraft maneuvering dynamics using the data from the sensors associated with the hub, obtaining at least one parameter associated with the blade dynamics based on the processing, and analyzing the at least one parameter to control at least one of the rotorcraft and the blades.

Description:
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
     This invention was made with Government support with the United States Army under Contract No. W911W6-10-2-0004. The Government has certain rights in this invention. 
    
    
     BACKGROUND 
     On an aircraft, such as a rotorcraft, mechanical stops may be used to prevent blades from contacting one or more objects. For example, mechanical stops may impose a limit such that rotor blades may be precluded from hitting the body or frame of a helicopter. 
     The rotor information, or state, used by a helicopter diagnostic or flight control system can be measured in real-time and used to augment vehicle flight dynamics, improve disturbance rejection, detect damage, and limit rotor loads. This rotor information can include parameters such as flapping, pitching, and lead-lag accelerations, velocities, positions, and moments. Rotor states are not directly used in current helicopter flight control systems because the harsh rotor operating environment (centrifugal force, rain, dirt, sand, sunlight, vibrations, EMI, etc.), the difficulty providing reliable power and data to and from rotor sensors and the difficulty with fuselage dynamics contaminate sensed rotor state information. 
     BRIEF SUMMARY 
     An embodiment is directed to a method applied to a rotorcraft comprising a rotor including blades, the method comprising: obtaining data from a plurality of sensors located on the rotorcraft, wherein a first plurality of the sensors is associated with a hub of the rotorcraft and a second plurality of the sensors is associated with the blades, processing the data to isolate blade dynamics using the data from the sensors associated with the blade from rotorcraft maneuvering dynamics using the data from the sensors associated with the hub, obtaining at least one parameter associated with the blade dynamics based on the processing, and analyzing the at least one parameter to control at least one of the rotorcraft and the blades. 
     An embodiment is directed to an apparatus for use in a rotorcraft having at least one rotor with blades, the apparatus comprising: 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 from a plurality of sensors located on the rotorcraft, wherein a first plurality of the sensors is associated with a hub of the rotorcraft and a second plurality of the sensors is associated with the blades, process the data to isolate blade dynamics from rotorcraft maneuvering dynamics, obtain at least one parameter associated with the blade dynamics based on the processing, and analyze the at least one parameter to control at least one of the rotorcraft and the blades. 
     An embodiment is directed to an aircraft comprising: an airframe, a hub extending from the airframe and which rotates about an axis, blades extending from the hub which generate lift according to the rotation of the hub, a plurality of hub sensors disposed at the hub which measure motion associated with the hub of the aircraft, a plurality of blade sensors disposed at the blades which measure motion associated with each of a plurality of blades of the aircraft, and a control computer configured to: obtain data from the hub sensors and the blade sensors, process the data to isolate blade dynamics using the data from the blade sensors from aircraft maneuvering dynamics using the data from the hub sensors, obtain at least one parameter associated with the blade dynamics based on the processing, and control the blades using the obtained one parameter. 
     Additional embodiments are described below. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The present disclosure is illustrated by way of example and not limited in the accompanying figures in which like reference numerals indicate similar elements. 
         FIG. 1A  is a general perspective side of an exemplary rotary wing aircraft; 
         FIG. 1B  is a schematic block diagram illustrating an exemplary computing system; 
         FIG. 2  is a block diagram of an exemplary system environment; 
         FIG. 3  illustrates a flow chart of an exemplary method; and 
         FIGS. 4A-4C  illustrates block diagrams of exemplary system environments. 
     
    
    
     DETAILED DESCRIPTION 
     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 determining one or more parameters associated with one or more blades of an aircraft. In some embodiments, a relative acceleration technique may be used to eliminate fuselage motion. In some embodiments, acceleration may be measured at a blade root, which may be used to minimize or eliminate high order effects. 
       FIG. 1A  illustrates a general perspective view of a helicopter embodiment  10  of a rotary wing aircraft for use with aspects of the present. invention. The helicopter includes a main rotor assembly  12  and tail rotor assembly  14 , A mechanical lead/lag damper D (illustrated schematically) is mounted between a rotor hub  12 H and each rotor blade assembly  12 B to react in-plane edgewise motion of each blade assembly  12 B to dampen vibration, Although a particular helicopter configuration is illustrated and described in the disclosed embodiment, other configurations and/or machines, such as high speed compound rotary wing aircraft with supplemental translational thrust systems, dual contra-rotating, coaxial rotor system aircraft, turbo-props, tilt-rotors and tilt-wing aircraft, will also benefit from the present invention. 
     Referring to  FIG. 1B , an exemplary computing system  100  is shown. Computing system  100  may be part of a flight control system of the aircraft  10 . The system  100  is shown as including a memory  102 . The memory  102  may store executable instructions. The executable instructions may be stored or organized in any manner and at any level of abstraction, such as in connection with one or more applications, processes, routines, procedures, methods, etc. As an example, at least a portion of the instructions are shown in  FIG. 1B  as being associated with a first program  104   a  and a second program  104   b.    
     The instructions stored in the memory  102  may be executed by one or more processors, such as a processor  106 . The processor  106  may be coupled to one or more input/output (I/O) devices  108 . In some embodiments, the I/O device(s)  108  may be configured to receive the sensor data from the hub sensors  402  and blade sensors  404  (see, e.g.,  FIG. 4A ). While not required in all aspects, the I/O device(s)  108  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 control stick, a joystick, a printer, a telephone or mobile device (e.g., a smartphone), etc. so as to also provide an interface to allow a user to interact with the system  100  in addition to the sensor data. Alternately, the user interface could be provided separately. 
     As shown, the processor  106  may be coupled to a number ‘n’ of databases,  110 - 1 ,  110 - 2 , . . .  110 -n. The databases  110  may be used to store data, such as data obtained from one or more sensors (e.g., accelerometers). In some embodiments, the data may pertain to one or more parameters associated with a blade of an aircraft (e.g., aircraft  10 ). 
     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  FIG. 1B . For example, in some embodiments, the memory  102  may be coupled to or combined with one or more of the databases  110 . While not required in all aspects, the memory  102  can be a magnetic medium, an optical medium or other like computer readable medium. 
     Turning now to  FIG. 2 , a block diagram of a system  200  in accordance with one or more embodiments is shown. The system  200  may be used to obtain one or more parameters associated with blade operation or motion. Blade or rotor motion may be used, potentially as a feedback mechanism, for purposes of flight controls. 
     The system  200  may include one or more sensors  202 . The sensors  202  may include accelerometers, such as gravimetric accelerometers. One or more sensors  202  may be located on, or associated with, a hub arm  12 H and a blade  12 B (see, e.g.,  FIG. 4C ). The sensors  202  may be configured to obtain data in connection with the axial, radial, and tangential directions associated with, e.g., the rotor system  12 . While not required in all aspects, the sensors  202  include sensors  402  on the hub arm  12 H, and other sensors  404  on the root of the blade  12 B. Measurement at the root includes minimal high order blade bending and torsional detection. Where these measurements are intended for flight control feedback use, it is desirable to measure the first order blade movement, so the root measurement is thought to be the most effective location. The sensors  202  are also mounted as sensors  402  on the hub-arm  12 H and as other sensors  404  on the inboard portion of the blade  12 B. Because the hub-arm  12 H will have minimal flapping and lead-lag deflection (only root bending, which is relatively small), the hub-arm  12 H mounted accelerometers provide a steady reference point for comparison with the blade measurements. However, it is understood that other locations could be utilized. 
     The data provided by the sensors  202  may pertain to one or more angles, velocities, accelerations, positions, or any other parameter. The data may be processed in connection with a processing system  204 , such as a rotating frame processing system. The processing system  204  may include one or more components or devices, such as those described above in connection with  FIG. 1B . In some embodiments, the processing system  204  may be implemented as a processing unit on a rotor head. In some embodiments, the processing system  204  may be implemented in connection with a slip ring. 
     The processing system  204  (or one or more additional or alternative entities) may transform the data from a rotating frame to a fixed frame. Based on the transformation, one or more states associated with the operation of the aircraft may be obtained. For example, one or more states associated with the coning angle, the longitudinal tilt of the tip path plane (TPP), and the latitudinal tilt of the TPP may be obtained. 
     In some embodiments, as part of the processing in connection with the processing system  204 , one or more gains may be applied as shown in block  206 . 
     Based on the processing performed by the processing system  204 , one or more control laws may be defined in block  208 . For example, the control laws  208  may be defined to provide one or more metrics or requirements. Such requirements may include minimizing hub moments, maximizing aircraft maneuverability, maximizing gust rejection, and maintaining or maximizing stability margins. 
     The control laws  208  may, in turn, drive one or more commands  210  (e.g., servo commands). For example, control of a swashplate, an actuator, and individual blade control may be provided via the commands  210 . 
     In some embodiments, blade motion parameters may be used for scheduling maintenance operations. For example, data regarding blade motion may be analyzed to determine if a blade is approaching a mechanical or theoretical limit If the blade is approaching such a limit, a maintenance or service activity may be scheduled. 
     Turning now to  FIG. 3 , a flow chart of an exemplary method  300  is shown. The method  300  may be executed by one or more systems, components, or devices, such as those described herein (e.g., the system  100  and/or the system  200 ). The method  300  may be used to robustly and accurately obtain one or more parameters associated with the motion of a blade of an aircraft. 
     In block  302 , data associated with the operation of the aircraft may be obtained from one or more sensors (e.g., sensors  202 ). The data may pertain to the movements or positions of one or more blades of the aircraft. 
     In block  304 , the data of block  302  may be processed. For example, the data may be processed by the processing system  204  of  FIG. 2 . 
     In block  306 , the processed data of block  304  may be filtered. The filtering may be done to remove extraneous data, to reduce the impact of noise on one or more measurements, or to obtain a data profile that more closely mirrors or resembles the physical world. 
     In block  308 , one or more parameters associated with the blades may be derived or obtained. Such parameters may be obtained based on an integration of the filtered data of block  306 . 
     In block  310 , the parameters of block  308  may be analyzed to control or regulate the operation of the blades or the aircraft. For example, the parameters may be applied in connection with a blade frame or a vehicle frame. 
     In block  312 , one or more maintenance activities may be scheduled. For example, if the data (blocks  304  and  306 ) or parameters (block  308 ) indicate that the operation of a blade is causing the blade to approach a mechanical stop or limit within a threshold, a maintenance activity may be scheduled to obtain a greater degree of margin from the threshold. 
     Turning to  FIGS. 4A-4B , system environments  400  and  450  in connection with one or more embodiments are shown, and  FIG. 4C  shows, for a single blade  12 B, the location of the sensors  402  on the hub  12 H and the sensors  404  on the root end of the blade  12 B. One or both of the systems  400  and  450  may be implemented in connection with one or more components, devices, or other systems, such as those described herein (e.g., the systems  100  and  200 ). 
     As represented in  FIG. 4A , an aircraft (e.g., aircraft  10 ) may have a count ‘N’ of blades (denoted as blade  1 , blade  2 , . . . blade N). Each of the ‘N’ blades may be associated with, or include, one or more hub-arm sensors  402  and blade/spindle sensors  404 . The sensors  402 ,  404  may include accelerometers, such that the sensors may output or provide data pertaining to acceleration. The data may include one or more identifiers or tags in order to associate a given portion of the data with a particular sensor or blade. 
     The acceleration data may be provided to a device  408  that may be used to transfer the data and/or power. The device  408  may be used to transition from a rotating frame to a fuselage fixed frame. In some embodiments, the device  408  may include a slip ring. 
     The output of the device  408  may be provided on a bus to one or more flight control computers (denoted as FCC 1 , FCC 2 , FCC 3 ) and/or a health monitoring system  416 . 
     The health monitoring system  416  may be coupled to one or more databases, such as the databases  110 . The acceleration data, potentially subject to one or more transformations or processing, may be stored in the databases  110 . The acceleration data may be analyzed by the health monitoring system  416  in order to provide status regarding aircraft state or health. For example, the state or health regarding one or more of the blades may be determined by the health monitoring system  416 . 
     The flight control computers FCC 1  through FCC 3  may manipulate or process the acceleration data to generate commands to be utilized by one or more flight control systems. In this respect, the commands may be provided to one or more servos (denoted as servo  1 , servo  2 , . . . servo N). The servos may be fixed frame and/or on-blade rotating frame servos. 
     Referring to  FIG. 4B , additional details regarding the operation of one or more of the flight control computers in accordance with one or more embodiments is shown. The data obtained from the device  408  may be analyzed for each of the blades. In this respect, the data  452  and  454  may correspond to the data obtained from the hub-arm sensors  402  and the blade/spindle sensors  404 , respectively, for each of the blades. 
     The data  452 ,  454  for each of the blades may be processed by devices  460  to determine the acceleration of the blade relative to a hub-arm. A device  470  may perform further processing to transform from an individual blade to multiple blades, or from a rotating frame to a fixed frame. 
     The output of the device  470  may be provided to one or more feedback devices  480 . The feedback device  480  may implement one or more filters and/or gains/amplifiers to generate one or more commands (e.g., servo commands). The commands output by the feedback device  480  may be used to adjust or modify the state of one or more aircraft components or devices, such as one or more of the blades, potentially in response to dynamic conditions (e.g., gusts of wind). 
     The output of the device  470  may be provided to a FCC cross-channel comparison device  490 . The device  490  may be used to output the results of the processing performed by the devices  460  and/or  470  to other flight control computers. The sharing of such results or data may be used for purposes of redundancy or safety, or to guard against a failure of a given flight control computer. 
     As described herein, by measuring the acceleration of the hub and the blade, it is possible to isolate the blade dynamics from the rest of the aircraft maneuvering dynamics. 
     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.