Abstract:
Embodiments are directed to obtaining data from at least one sensor, processing, by a processor, the data to determine an independent rotor phase lag for each of a plurality of axes associated with a rotorcraft, and issuing, by the processor, at least one command to provide for on-axis moments in accordance with the independent rotor phase lag for each of the axes.

Description:
BACKGROUND 
       [0001]    On an aircraft, such as a rotorcraft, rigid rotor design is typically associated with a small amount of rotor phase lag, that is, the time between the feathering of a blade and the resulting moment is small when compared to a traditional rotor system where approximately 90 degrees of phase lag is expected. 
         [0002]    Analysis of a rigid rotor system has shown that the rotor phase lag can vary significantly with speed. In addition to varying with speed, feathering commands introduced at different positions around the rotor will generate moments at different rates. This means that phase lag varies around the rotor as well. As a result, it is difficult to ensure correct on-axis commands for pitching and rolling maneuvers. For the particular case of a coaxial rotor, differential cyclic commands may result in off-axis net moments, and gang cyclic commands may result in undesirable inter-hub moments. 
       BRIEF SUMMARY 
       [0003]    An embodiment is directed to a method comprising: obtaining data from at least one sensor, processing, by a processor, the data to determine an independent rotor phase lag for each of a plurality of axes associated with a rotorcraft, and issuing, by the processor, at least one command to provide for on-axis moments in accordance with the independent rotor phase lag for each of the axes. 
         [0004]    An embodiment is directed to an 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, process the data to determine an independent rotor phase lag for each of a plurality of axes associated with a rotorcraft, and issue commands to provide for on-axis moments in accordance with the independent rotor phase lag for each of the axes. 
         [0005]    An embodiment is directed to a rotorcraft comprising: at least one rotor comprising a plurality of blades, a plurality of sensors associated with the at least one rotor, and a control system configured to: obtain data from the sensors, process the data to determine an independent rotor phase lag for each of a plurality of axes associated with the rotorcraft, and issue commands to provide for on-axis moments in accordance with the independent rotor phase lag for each of the axes. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0006]    The present disclosure is illustrated by way of example and not limited in the accompanying figures in which like reference numerals indicate similar elements. 
           [0007]      FIG. 1A  is a general perspective side view of an exemplary rotary wing aircraft; 
           [0008]      FIG. 1B  is a schematic block diagram illustrating an exemplary computing system; 
           [0009]      FIG. 2  is a block diagram of an exemplary system environment; and 
           [0010]      FIG. 3  illustrates a flow chart of an exemplary method. 
       
    
    
     DETAILED DESCRIPTION 
       [0011]    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 are 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. 
         [0012]    Exemplary embodiments of apparatuses, systems, and methods are described for ensuring correct on-axis commands for an aircraft (e.g., a rotorcraft, such as a helicopter) by adjusting the phasing of kinematics for each axis separately or independently to obtain an on-axis response. In some embodiments, such adjustments may be based on one or more tables or maps. 
         [0013]      FIG. 1A  illustrates an exemplary rotary wing aircraft  10 . The aircraft  10  is shown as having a dual, counter-rotating main rotor system  12 , which rotates about a rotating main rotor shaft  14 U, and a counter-rotating main rotor shaft  14 L, both about an axis of rotation A. Other types of configurations may be used in some embodiments, such as a single rotor system  12 . 
         [0014]    The aircraft  10  includes an airframe F which supports the main rotor system  12  as well as an optional translational thrust system T which provides translational thrust during high speed forward flight, generally parallel to an aircraft longitudinal axis L. 
         [0015]    A main gearbox G located above the aircraft cabin drives the rotor system  12 . The translational thrust system T may be driven by the same main gearbox G which drives the rotor system  12 . The main gearbox G is driven by one or more engines E. As shown, the main gearbox G may be interposed between the engines E, the rotor system  12 , and the translational thrust system T. 
         [0016]    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.    
         [0017]    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 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. The I/O device(s)  108  may be configured to provide an interface to allow a user to interact with the system  100 . 
         [0018]    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 physical parameters, such as advance ratio and air density. 
         [0019]    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 . 
         [0020]    Referring to  FIG. 2 , a system  200  in accordance with one or more embodiments is shown. The system  200  may be implemented in connection with one or more of the components or devices described above in relation to the system  100 . The system  200  may be used to correct on-axis commands by independently adjusting phasing kinematics for one or more axes. The system  200  may be built off of, or adopt principles of, a fly-by-wire (FBW) system with an electronic mixer. 
         [0021]    The system  200  may include a control computer  202 , such as a flight control computer (FCC). The control computer  202  may be coupled to one or more sensors  216 . The sensors  216  may be configured to measure one or more parameters, such as temperature, pressure, density, speed (e.g., vertical speed), advance ratio, etc. Such parameters may be measured during flight of an aircraft. 
         [0022]    The control computer  202  may include one or more schedules, maps, or tables, such as a first table  222   a  and a second table  222   b . As described above, in some embodiments on-axis commands may be provided by adjusting a phasing of kinematics for each axis separately to obtain an on-axis response. In some embodiments, a separate table  222  may be created for each of one or more axes (e.g., pitch, roll) that maps out the phase lag needed to generate correct on-axis moments at varying airspeeds. 
         [0023]    The tables  222  may be used so that control inputs going through kinematics generate correct on-axis moments. The tables  222  may be populated based upon a model or type of rotor that is used on a given aircraft platform. Values for the tables  222  may be determined based on flight testing. 
         [0024]    The tables  222  may map parameters or sensor values (e.g., values obtained from the sensors  216 ) to one or more commands to generate on-axis moments or responses. The control computer  202  may issue the commands to one or more actuators  234  to provide for such on-axis moments. In some embodiments, the commands issued by the control computer  202  may correspond to orthogonal cyclic commands. The commands may be orthogonal if phasing is the same for pitch and roll axes. If phasing is different for the pitch and roll axes, non-orthogonal cyclic commands may be provided. The commands may be associated with a swashplate. 
         [0025]    In some embodiments, individual blade control (e.g., individual blade pitch around azimuth) may be provided via the commands. 
         [0026]    The system  200 , or portions thereof, may correspond to an electronic control system. In some embodiments, an analogous mechanical control system may be used. 
         [0027]    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 provide for flight controls in order to obtain an on-axis response from an aircraft. 
         [0028]    In block  302 , data associated with the operation of the aircraft may be obtained from one or more sensors (e.g., sensors  216 ). The data may pertain to one or more parameters, such as environmental parameters. 
         [0029]    In block  304 , the data of block  302  may be processed. For example, the data may be processed by the control computer  202 . The data may be processed in accordance with one or more tables (e.g., tables  222 ). 
         [0030]    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 minors or resembles the physical world. 
         [0031]    In block  308 , one or more commands or directives may be issued. The commands may represent a phase shift relative to traditional on-axis commands in such a way that control inputs going through kinematics may generate correct on-axis moments. The commands may be issued independently, or that is to say, that the commands may correspond to different axes of the aircraft. The commands may be used to adjust rotor phasing separately for each axis. 
         [0032]    The method  300  is illustrative. In some embodiments, one or more of the blocks or operations (or a portion thereof) may be optional. In some embodiments, additional blocks or operations not shown may be included. In some embodiments, the blocks or operations may be executed in an order or sequence that is different from what is shown. 
         [0033]    As described herein, embodiments of the disclosure may be used to generate correct or proper on-axis moments through separate phase scheduling of each command axis. Traditional mixing may provide an ability to mix-in a command from a first axis to offset its expected effect on one or more additional axes. Embodiments of the disclosure may be used to adjust rotor phasing separately for one or more axes as the rotor phasing changes with, e.g., one or more parameters, in order to provide corrected kinematics for on-axis moment generation. Embodiments of the disclosure may prevent off-axis moments from being generated due to differential cyclic commands, or inadvertent inter-hub moments from being generated due to gang cyclic commands in coaxial applications. 
         [0034]    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. 
         [0035]    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. 
         [0036]    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. 
         [0037]    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.