(19)
(11)EP 2 738 090 B1

(12)EUROPEAN PATENT SPECIFICATION

(45)Mention of the grant of the patent:
26.06.2019 Bulletin 2019/26

(21)Application number: 13194455.5

(22)Date of filing:  26.11.2013
(51)International Patent Classification (IPC): 
B64C 27/00(2006.01)
B64C 27/46(2006.01)

(54)

Rotary wing aircraft blade tracking

Drehflügelflugzeug-Blattverfolgung

Suivi de pale d'aéronef à voilure tournante


(84)Designated Contracting States:
AL AT BE BG CH CY CZ DE DK EE ES FI FR GB GR HR HU IE IS IT LI LT LU LV MC MK MT NL NO PL PT RO RS SE SI SK SM TR

(30)Priority: 29.11.2012 US 201213688388

(43)Date of publication of application:
04.06.2014 Bulletin 2014/23

(73)Proprietor: Sikorsky Aircraft Corporation
Stratford, CT 06615 (US)

(72)Inventors:
  • Fang, Austin
    Fairfield, CT Connecticut 06824 (US)
  • Lozano, Steven P.
    Wolcott, CT Connecticut 06716 (US)

(74)Representative: Schmitt-Nilson Schraud Waibel Wohlfrom Patentanwälte Partnerschaft mbB 
Pelkovenstraße 143
80992 München
80992 München (DE)


(56)References cited: : 
EP-A2- 2 431 273
EP-A2- 2 662 741
EP-A2- 2 433 866
WO-A1-2009/085639
  
      
    Note: Within nine months from the publication of the mention of the grant of the European patent, any person may give notice to the European Patent Office of opposition to the European patent granted. Notice of opposition shall be filed in a written reasoned statement. It shall not be deemed to have been filed until the opposition fee has been paid. (Art. 99(1) European Patent Convention).


    Description


    [0001] The subject matter disclosed herein relates generally to rotary wing aircraft, and in particular to tracking blades of a rotary wing aircraft.

    [0002] Conventional methods for measuring blade track use optical camera equipment sensitive to visible and electromagnetic light wave spectra to detect contrast differences as blades block the background sky. The time difference between the leading and trailing edges of each blade pass is used to calculate blade track as well as lead/lag motions. Some of the shortcomings of conventional methods are the lack of reliable timing triggers due to low contrast differences between light colored blades and the background sky, along with increased rotor speed with reduced blade chord width. The low detection of lighter color blades works against the process of gathering blade track data. In addition, the blade track is only measured at one azimuthal location in the blade path above the optical camera.

    [0003] EP 2 433 866 A2 discloses a rotor track and balance system for rotorcraft that includes a data processing unit, a tachometer sensor and at least one accelerometer. The tachometer sensor is located remotely from the data processing unit and is mounted proximate to the rotating blades of the rotorcraft. The tachometer sensor is adapted to measure the speed and position of the rotating blades and to wirelessly transmit speed and position data to the data processor. Each accelerometer is adapted to measure vibration anomalies in the rotating blades and to wirelessly transmit vibration data to the data processor. The at least one accelerometer is also located remotely from the data processing unit and is preferably mounted proximate to the rotating blades of the rotorcraft. However, the vibration sensors could be positioned remotely from the rotating blades. The data processing unit synchronizes the wireless data transmitted from the tachometer sensor and the wireless accelerometer(s) and determines necessary adjustments to be made in order to reduce the vibration anomalies in the rotor blades.

    [0004] The invention relates to a blade tracking system for a rotary wing aircraft, and to a rotary wing aircraft according to the appended claims.

    [0005] One embodiment includes a blade tracking system according to claim 1 for a rotary wing aircraft, the system comprising a plurality of blade sensors mounted on and along the blade span of the rotary wing aircraft, the blade sensors wirelessly transmitting blade data and the plurality of sensors being capable of pre-processing of data; a reference sensor mounted to the rotary rotor hub of the wing aircraft, the blade driven by the rotor hub, the reference sensor transmitting reference data; and a processor receiving the blade data and the reference data, the processor determining at least one of lead-lag, flap and pitch of the blade in response to the blade data and the reference data. Particular embodiments may include any of the following optional features, alone or in combination: The reference sensor may transmit the reference data wirelessly. The blade sensor wirelessly may transmit raw data as the blade data. The blade sensor wirelessly transmit preprocessed data as the blade data. The at least one of lead-lag, flap and pitch of the blade may be determined for a tip of the blade.

    [0006] The blade data may indicate blade motion in nine degrees of freedom.

    [0007] The nine degrees of freedom may include three axis linear acceleration, three axis angular acceleration, and three axis magnetic motion sensing.

    [0008] The blade tracking system further may comprise a second blade sensor mounted on a second blade of the rotary wing aircraft, the second blade sensor wirelessly transmitting second blade data.

    [0009] The blade tracking system further comprise a tachometer generating a tachometer signal indicative of rotation phasing of a rotor hub.

    [0010] The processor may compute a distance between the blade and the second blade in response to the blade data, second blade data, reference data and tachometer signal.

    [0011] Another embodiment is a rotary wing aircraft including an airframe; a rotor hub; a rotor blade driven by the rotor hub; a blade sensor mounted on the blade, the blade sensor wirelessly transmitting blade data; a blade tracking system according to claim 1.

    [0012] Particular embodiments may include any of the following optional features, alone or in combination:
    The rotary wing aircraft may comprise an airframe; a rotor hub; a rotor blade driven by the rotor hub; and a blade sensor mounted on the blade. The blade sensor wirelessly may transmit blade data. A reference sensor may be mounted to the rotary wing aircraft. The reference sensor may transmit reference data. A processor may receive the blade data and the reference data. The processor may determine at least one of lead-lag, flap and pitch of the blade in response to the blade data and the reference data.

    [0013] The reference sensor may transmit the reference data wirelessly.

    [0014] The blade sensor wirelessly may transmit raw data as the blade data.

    [0015] The blade sensor wirelessly may transmit preprocessed data as the blade data.

    [0016] The at least one of lead-lag, flap and pitch of the blade may be determined for a tip of the blade.

    [0017] The blade data may indicate blade motion in nine degrees of freedom.

    [0018] The nine degrees of freedom may include three axis linear acceleration, three axis angular acceleration, and three axis magnetic motion sensing.

    [0019] The rotary wing aircraft further may comprise a second blade sensor mounted on a second blade of the rotary wing aircraft, the second blade sensor wirelessly transmitting second blade data.

    [0020] The rotary wing aircraft further may comprise a tachometer generating a tachometer signal indicative of rotation phasing of a rotor hub.

    [0021] The processor may compute a distance between the blade and the second blade in response to the blade data, second blade data, reference data and tachometer signal.

    [0022] Other aspects, features, and techniques of the invention will become more apparent from the following description taken in conjunction with the drawings.

    [0023] Referring now to the drawings wherein like elements are numbered alike in the several FIGURES, in which:

    FIG. 1 depicts a rotary wing aircraft in an exemplary embodiment;

    FIG. 2 depicts a blade tracking system in an exemplary embodiment;

    FIG. 3 depicts wireless sensors in a rotor blade in an exemplary embodiment;

    FIG. 4 is a top down view of a rotor blade in an exemplary embodiment;

    FIG. 5 is a tip view of a rotor blade in an exemplary embodiment; and

    FIG. 6 depicts blade tracking for proximity detection in an exemplary embodiment.



    [0024] FIG. 1 illustrates a rotary wing aircraft 10 having a main rotor assembly 12 in an exemplary embodiment. The aircraft 10 includes an airframe 14 having an extending tail 16 which mounts a tail rotor system 18, such as an anti-torque system, a translational thrust system, a pusher propeller, a rotor propulsion system, and the like. The main rotor assembly 12 is driven about an axis of rotation R through a main gearbox (illustrated schematically at 20) by one or more engines 22. The main rotor assembly 12 includes a plurality of rotor blades 24 mounted to a rotor hub 26. Although a particular rotary wing aircraft configuration is illustrated, other configurations and/or machines, such as high speed compound rotary wing aircraft with supplemental translational thrust systems, dual contra-rotating aircraft, coaxial rotor system aircraft, turbo-props, tilt-rotors and tilt-wing aircraft, will also benefit from embodiments of the invention.

    [0025] FIG. 2 depicts a blade tracking system in an exemplary embodiment. One or more blades 24 include blade sensors 30. Blade sensors 30 are located along the span of a blade 24 to obtain blade data as the blade rotates. A reference sensor 32 is positioned in rotor hub 26 and provides reference data along with blade azimuth. The blade sensors 30 and reference sensor 32 wirelessly communicate with a receiver 34 that provides the blade data and reference data to processor 36. In alternative embodiments, reference sensor 32 may be wired to processor 36. The receiver 34 and processor 36 may be mounted on rotor hub 26 or in the non-rotating air-frame 14. Processor 36 may be implemented using a general-purpose microprocessor executing a computer program to perform the operations described herein. Processor 36 may be implemented using hardware (e.g., ASIC, FPGA, microcontroller) and/or a combination of hardware and software.

    [0026] The blade sensors 30 and reference sensor 32 may be micro-electromechanical systems (MEMS) based sensors designed to be system-on-chips that have the ability for local processing of data and data transmission through wireless radio signals back to processor 36, via receiver 34. Exemplary MEMS embedded sensors include gyroscopes, accelerometers, magnetometers, pressure transducers, and strain gages, whose collective data from each of the locations is fused together by processor 36, along with known blade material properties, to accurately determine blade motion and position in nine degrees of freedom. In an exemplary embodiment, the degrees of freedom are three axis linear acceleration, three axis angular acceleration, and three axis of magnetic motion sensing.

    [0027] Blade sensors 30 and reference sensor 32 may be powered by a battery positioned proximate the sensor. Alternatively, energy harvesting devices may be used to convert motion of the rotor hub/blades to electrical power. In other embodiments, the sensors may be line powered from a source delivered to the rotating frame.

    [0028] Processor 36 executes methods to filter, combine, and process data from individual sensors. Blade data from blade sensors 30 and reference data from reference sensor 32 may be raw data or may be pre-processed data from the reference sensor,and are pre-processed data from the blade sensors.

    [0029] The methods also utilize blade properties determined from empirical testing for accurate blade stiffness in each of the degrees of freedom. Reference data from reference sensor 32 is used to provide the azimuth for the blades and provides a value to offset the data from blade sensors 30. For example, forces on the reference sensor 32 can be subtracted from the forces measured by blade sensors 30 to provide an absolute indication of forces on the blades 24. The output of processor 36 includes one or more blade parameters, such as blade position, lead/lag, flap, and pitch, at one or more locations along each blade 24 (e.g., the blade tip).

    [0030] The blade parameters output by processor 36 may be used by one or more aircraft systems. A flight control system (FCS) 40 may use the blade parameters to adjust operation of the aircraft to improve flight characteristics (e.g., reduce blade vibration). A blade proximity detector 42 may use positional information of blades 24 to reduce likelihood of blade collision, in a dual rotor aircraft. The blade proximity determination is described in further detail with reference to FIG. 6. A post flight analysis unit 44 may use blade parameters for flight evaluation and scheduling of maintenance. An adaptive rotor controller 46 may use the blade parameters to adjust characteristics of one of more blades 24, in an aircraft that employs mission adaptive rotor blades.

    [0031] FIG. 3 depicts wireless sensors in a rotor blade in an exemplary embodiment. In FIG. 3, reference sensor 32 is positioned in rotor arm hub 50. A blade spindle 52 supports blade 24. It is understood that reference sensor 32 may be positioned in a different portion of the rotor hub, and FIG. 3 depicts an exemplary embodiment. Blades sensors 30 are positioned at or more locations along blade 24. In exemplary embodiments, at least one blade sensor 30 is positioned proximate the tip of blade 24. In exemplary embodiments, blade sensors 30 are positioned on opposing sides of a longitudinal, feathering axis of blade 24. This arrangement facilitates detection of blade pitch.

    [0032] FIG. 4 is a top down view of a rotor blade in an exemplary embodiment. FIG. 4 illustrates tracking of lead-lag of blade 24. The amount of lead-lag is represented as an angle, A, shown in FIG. 4. As noted above, by using the blade data from blade sensors 30 and reference data from reference sensor 32, the lead-lag for each blade 24 can be computed by processor 36.

    [0033] FIG. 5 is a tip view of a rotor blade in an exemplary embodiment. FIG. 5 illustrates tracking of flap and pitch of blade 24. The amount of flap is represented as distance, B, shown in FIG. 5. The amount of blade pitch is represented as angle, C, shown in FIG. 5. As noted above, by using the blade data from blade sensors 30 and reference data from reference sensor 32, the flap and pitch for each blade 24 can be computed by processor 36.

    [0034] FIG. 6 depicts blade tracking for proximity detection in an exemplary embodiment. In FIG. 6, the rotary wing aircraft includes two, counter rotating blades 24. In such aircraft, it is desirable to detect if the tips of blades 24 are in threat of coming in contact. Blades 24 include one or more blade sensors 30, as described above.

    [0035] Reference sensor 32 is mounted to the rotor hub, on the rotor shaft 60. A tachometer 64 is mounted, for example, to swashplate 62.

    [0036] Processor 36 uses the blade data from blade sensors 30, reference data from reference sensor 32 and a tachometer signal from tachometer 64 to determine a distance, D, between the upper and lower rotor blades 24 upon crossing. The tachometer signal is used to determine when the blades 24 cross each other (e.g., rotation phasing). The blade data and reference data are used to compute the distance between blade tips upon crossing.

    [0037] Processor 36 or blade proximity detector 42 may compute distance D. In one embodiment, processor 36 computes distance, D, between blades at crossing and outputs the distance to blade proximity detector 42 for analysis and corrective action, if necessary. In alternate embodiments, processor 36 forwards blade data, reference data and tachometer signal to blade proximity detector 42 to compute distance, D. A direction cosine matrix and quaternions may be generated from the blade data and reference data to calculate orientation and rotation of the blades 24 in three dimensions. Together with geometric constraints, the distance, D, between the upper and lower blades 24 is derived.

    [0038] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. While the description of the present invention has been presented for purposes of illustration and description, it is not intended to be exhaustive or limited to the invention in the form disclosed. Many modifications, variations, alterations or substitutions not hereto described will be apparent to those of ordinary skill in the art without departing from the scope of the invention. Additionally, while various embodiments of the invention have been described, it is to be understood that aspects of the invention may include only some of the described embodiments. Accordingly, the invention is not to be seen as limited by the foregoing description, but is only limited by the scope of the appended claims.


    Claims

    1. A blade tracking system for a rotary wing aircraft (10), the system comprising:

    a plurality of blade sensors (30) mounted on and along a span of a blade (24) of the rotary wing aircraft (10), the blade sensors (30) wirelessly transmitting blade data, the plurality of blade sensors being capable of pre-processing of data;

    a reference sensor (32) mounted to a rotating rotor hub (26) of the rotary wing aircraft (10), the blade (24) driven by the rotor hub (26), the reference sensor (32) transmitting reference data; and

    a processor (36) receiving the blade data and the reference data, the processor (36) determining at least one of lead-lag, flap and pitch of the blade in response to the blade data and the reference data.


     
    2. The blade tracking system of claim 1 wherein:
    the reference sensor (32) wirelessly transmits the reference data.
     
    3. The blade tracking system of claim 1 or 2, wherein:
    the blade sensors (30) wirelessly transmit raw data as the blade data.
     
    4. The blade tracking system of any of claims 1 to 3, wherein:
    the blade sensors (30) wirelessly transmit preprocessed data as the blade data.
     
    5. The blade tracking system of any of claims 1 to 4 wherein:
    the at least one of lead-lag, flap and pitch of the blade is determined for a tip of the blade (24).
     
    6. The blade tracking system of any of claims 1 to 5, wherein:
    the blade data indicates blade motion in nine degrees of freedom.
     
    7. The blade tracking system of claim 6 wherein:
    the nine degrees of freedom include three axis linear acceleration, three axis angular acceleration, and three axis magnetic motion sensing.
     
    8. The blade tracking system of any of claims 1 to 7, further comprising:
    a second blade sensor (30) mounted on a second blade (24) of the rotary wing aircraft (10), the second blade sensor (30) wirelessly transmitting second blade data.
     
    9. The blade tracking system of claim 8 further comprising:
    a tachometer (64) generating a tachometer signal indicative of rotation phasing of a rotor hub (26).
     
    10. The blade tracking system of claim 9 wherein:
    the processor (36) computes a distance between the blade (24) and the second blade (24) in response to the blade data, second blade data, reference data and tachometer signal.
     
    11. A rotary wing aircraft (10) comprising:

    an airframe (14);

    a rotor hub (26);

    a rotor blade (24) driven by the rotor hub (26);

    a blade tracking system according to any of the previous claims.


     


    Ansprüche

    1. Blattverfolgungssystem für ein Drehflügelflugzeug (10), wobei das System Folgendes umfasst:

    eine Vielzahl von Blattsensoren (30), die an und entlang einer Blattlänge eines Blatts (24) des Drehflügelflugzeugs (10) angebracht ist, wobei die Blattsensoren (30) Blattdaten drahtlos übermitteln, wobei die Vielzahl von Blattsensoren in der Lage ist, Daten vorzuverarbeiten;

    einen Referenzsensor (32), der an einer rotierenden Rotornabe (26) des Drehflügelflugzeugs (10) angebracht ist, wobei das Blatt (24) von der Rotornabe (26) angetrieben wird, wobei der Referenzsensor (32) Referenzdaten übermittelt; und

    einen Prozessor (36), der die Blattdaten und die Referenzdaten empfängt, wobei der Prozessor (36) mindestens eines aus Voreilung-Nacheilung, Schlag und Anstellung des Blatts als Reaktion auf die Blattdaten und die Referenzdaten ermittelt.


     
    2. Blattverfolgungssystem nach Anspruch 1, wobei: der Referenzsensor (32) die Referenzdaten drahtlos übermittelt.
     
    3. Blattverfolgungssystem nach Anspruch 1 oder 2, wobei:
    die Blattsensoren (30) Rohdaten als Blattdaten drahtlos übermitteln.
     
    4. Blattverfolgungssystem nach einem der Ansprüche 1 bis 3, wobei:
    die Blattsensoren (30) vorverarbeitete als Blattdaten drahtlos übermitteln.
     
    5. Blattverfolgungssystem nach einem der Ansprüche 1 bis 4, wobei:
    das mindestens eine aus Voreilung-Nacheilung, Schlag und Anstellung des Blatts für eine Spitze des Blatts (24) ermittelt wird.
     
    6. Blattverfolgungssystem nach einem der Ansprüche 1 bis 5, wobei:
    die Blattdaten eine Blattbewegung in neun Freiheitsgraden angeben.
     
    7. Blattverfolgungssystem nach Anspruch 6, wobei:
    die neun Freiheitsgrade die Erfassung der Linearbeschleunigung in drei Achsen, der Winkelbeschleunigung in drei Achsen und der Magnetbewegung in drei Achsen umfasst.
     
    8. Blattverfolgungssystem nach einem der Ansprüche 1 bis 7, ferner umfassend:
    einen zweiten Blattsensor (30), der an einem zweiten Blatt (24) des Drehflügelflugzeugs (10) angebracht ist, wobei der zweite Blattsensor (30) drahtlos zweite Blattdaten übermittelt.
     
    9. Blattverfolgungssystem nach Anspruch 8, ferner umfassend:
    ein Tachometer (64), das ein Tachometersignal erzeugt, das eine Drehphaseneinstellung einer Rotornabe (26) angibt.
     
    10. Blattverfolgungssystem nach Anspruch 9, wobei:
    der Prozessor (36) einen Abstand zwischen dem Blatt (24) und dem zweiten Blatt (24) als Reaktion auf die Blattdaten, die zweiten Blattdaten, die Referenzdaten und das Tachometersignal berechnet.
     
    11. Drehflügelflugzeug (10), umfassend:

    ein Flugwerk (14);

    eine Rotornabe (26);

    ein Rotorblatt (24), das von der Rotornabe (26) angetrieben wird;

    ein Blattverfolgungssystem nach einem der vorstehenden Ansprüche.


     


    Revendications

    1. Système de suivi de pale pour un aéronef à voilure tournante (10), le système comprenant :

    une pluralité de capteurs de pale (30) montés sur et le long d'une travée d'une pale (24) de l'aéronef à voilure tournante (10), les capteurs de pale (30) transmettant sans fil des données de pale, la pluralité de capteurs de pale pouvant pré-traiter des données ;

    un capteur de référence (32) monté sur un moyeu de rotor tournant (26) de l'aéronef à voilure tournante (10), la pale (24) étant entraînée par le moyeu de rotor (26), le capteur de référence (32) transmettant des données de référence ; et

    un processeur (36) recevant les données de pale et les données de référence, le processeur (36) déterminant au moins un élément parmi le mouvement de trainée, le volet et le pas de la pale en réponse aux données de pale et aux données de référence.


     
    2. Système de suivi de pale selon la revendication 1, dans lequel :
    le capteur de référence (32) transmet sans fil les données de référence.
     
    3. Système de suivi de pale selon la revendication 1 ou 2, dans lequel :
    les capteurs de pale (30) transmettent sans fil des données brutes en tant que données de pale.
     
    4. Système de suivi de pale selon l'une quelconque des revendications 1 à 3, dans lequel :
    les capteurs de pale (30) transmettent sans fil des données pre-traitées en tant que données de pale.
     
    5. Système de suivi de pale selon l'une quelconque des revendications 1 à 4, dans lequel :
    l'au moins un élément parmi le mouvement de trainée, le volet et le pas de la pale est déterminé pour une extrémité de la pale (24).
     
    6. Système de suivi de pale selon l'une quelconque des revendications 1 à 5, dans lequel :
    les données de pale indiquent le mouvement de pale dans neuf degrés de liberté.
     
    7. Système de suivi de pale selon la revendication 6, dans lequel :
    les neuf degrés de liberté incluent une accélération linéaire à trois axes, une accélération angulaire à trois axes et une détection de mouvement magnétique à trois axes.
     
    8. Système de suivi de pale selon l'une quelconque des revendications 1 à 7, comprenant en outre :
    un second capteur de pale (30) monté sur une seconde pale (24) de l'aéronef à voilure tournante (10), le second capteur de pale (30) transmettant sans fil des secondes données de pale.
     
    9. Système de suivi de pale selon la revendication 8, comprenant en outre :
    un tachymètre (64) générant un signal tachymétrique indiquant le phasage en rotation d'un moyeu de rotor (26).
     
    10. Système de suivi de pale selon la revendication 9, dans lequel :
    le processeur (36) calcule une distance entre la pale (24) et la seconde pale (24) en réponse aux données de pale, aux secondes données de pale, aux données de référence et au signal tachymétrique.
     
    11. Aéronef à voilure tournante (10) comprenant :

    une cellule (14) ;

    un moyeu de rotor (26) ;

    une pale de rotor (24) entraînée par le moyeu de rotor (26) ;

    un système de suivi de pale selon l'une quelconque des revendications précédentes.


     




    Drawing




















    Cited references

    REFERENCES CITED IN THE DESCRIPTION



    This list of references cited by the applicant is for the reader's convenience only. It does not form part of the European patent document. Even though great care has been taken in compiling the references, errors or omissions cannot be excluded and the EPO disclaims all liability in this regard.

    Patent documents cited in the description