(19)
(11)EP 3 367 076 B1

(12)EUROPEAN PATENT SPECIFICATION

(45)Mention of the grant of the patent:
05.08.2020 Bulletin 2020/32

(21)Application number: 18157480.7

(22)Date of filing:  19.02.2018
(51)International Patent Classification (IPC): 
G01G 19/07(2006.01)
B64F 1/22(2006.01)
G01G 19/08(2006.01)
B64D 45/00(2006.01)

(54)

SYSTEMS AND METHODS FOR AIRCRAFT MASS DETERMINATION

SYSTEME UND VERFAHREN ZUR BESTIMMUNG DER FLUGZEUGMASSE

SYSTÈMES ET PROCÉDÉS DE DÉTERMINATION DE MASSE D'AÉRONEF


(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: 24.02.2017 US 201715441436

(43)Date of publication of application:
29.08.2018 Bulletin 2018/35

(73)Proprietor: The Boeing Company
Chicago, IL 60606-1596 (US)

(72)Inventors:
  • KNEUPER, Nils
    CHICAGO, IL Illinois 60606-1596 (US)
  • CABOS, Ralf Rene
    CHICAGO, IL Illinois 60606-1596 (US)

(74)Representative: Bartelds, Erik et al
Arnold & Siedsma Bezuidenhoutseweg 57
2594 AC The Hague
2594 AC The Hague (NL)


(56)References cited: : 
WO-A1-89/03343
GB-A- 2 516 916
DE-A1- 19 724 092
  
      
    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

    BACKGROUND



    [0001] The present disclosure relates generally to systems and methods for determining a total mass of an aircraft while moving the aircraft, and more particularly to, example methods for determining an acceleration of a pushback vehicle and a pushback force applied by the pushback vehicle useful for determination of the total mass of the aircraft fully loaded.

    [0002] Developing optimal aircraft trajectories that minimize flight times, fuel burn, and associated environmental emissions can enhance air traffic flow and also help the aviation industry cope with increasing fuel costs. Optimal cruise altitudes are based on, among others, atmospheric constants and aerodynamic drag coefficients that are aircraft type dependent and vary per aircraft type, while a total lift and drag generated (units of force) depends on aircraft mass. Aircraft mass determinations can be difficult to determine.

    [0003] A mass of an aircraft includes many variables, such as an empty weight of the aircraft itself, an operating weight including weight of all catering and passenger service packs and crew equipment, a weight of fuel on board, a weight of all cargo/luggage, as well as a weight of all passengers.

    [0004] Current flight planning systems, as well as other aircraft systems needing a value for a total mass of an aircraft, generally use a weight estimate for each passenger and associated hand-carry luggage. However, an accuracy of these passenger weight assumptions is unknown because airlines do not weigh each passenger and hand-carry luggage separately. Additionally, real weight values may vary significantly depending on passengers from different world regions, or luggage restrictions for different airlines, further adding uncertainty to these standard weight assumptions.

    [0005] An accurate total mass of an aircraft is an important value useful for trajectory planning systems in order to plan an optimal flight route, as a most-optimal trajectory depends heavily on aircraft mass. Thus, what is needed is a method to accurately determine a mass value for a fully-loaded aircraft.

    [0006] Cited document WO 89/03343 A discloses a method for preventing overloading of nose wheel gears of aircraft being towed by a tractor and tractor for carrying out the method. As discussed in this document, when towing large aircraft with a tractor damage may at high speeds inadvertently be done to the nose wheel gears of the aircraft if the pilots of the aircraft apply the brakes. This can be avoided by automatic control whereby the transmitted force is sensed and the power and braking of the tractor is controlled on the basis of said sensing. By tractors of that kind it is difficult to sense the transmitted power directly. Instead, according to the disclosure of this document, the acceleration of the tractor and the supplied power of the tractor are sensed. On the basis thereof it is possible to calculate the transmitted force and to drive accordingly.

    [0007] Cited document DE 197 24 092 A1 discloses a method for measuring the mass of a heavy goods vehicle with trailer. The method involves detecting a first acceleration value, which represents the acceleration of the vehicle before operation of the brakes. A second acceleration value is detected, which represents the acceleration of the vehicle after operation of the brakes. The mass of the vehicle is calculated using the two acceleration values. A braking value may be detected, which represents the braking effect during the detection of the second acceleration value. The mass of the vehicle is then calculated using the detected braking value. The second acceleration value may be detected when the brakes are not acting on the wheels of the trailer.

    [0008] And finally, cited document GB 2 516 916 A discloses a method for determining the mass of a body, the method comprising: moving the body by the application and measurement of a first and then a second motive force; measuring the body's acceleration during both applications of motive force and calculating the body's mass using the measurements. Preferably the method comprises: a body mounted accelerometer and correction of acceleration measurements for the tilt angle of the accelerometer relative to the ground; correction for the angle measured between the true gravity horizontal and the area of ground the body moves across. The body may comprise an aircraft and its mass may be used in calculating: required takeoff thrust; fuel requirements; flight-path. The document further discloses an inertial mass system for determining a body's mass. Preferably the system uses an engine management system of an aircraft flight management system which is in communication with the inertial mass system to measure motive forces applied to the body. Preferably the system comprises a surface angle measuring device comprising a chassis, first and second laser range-finders measuring positions separated by an angle and an inclinometer fixed to the first range-finder is positioned having a horizontal axis perpendicular to a line bisecting the angle.

    SUMMARY



    [0009] In one example, a method is described as defined in independent claim 1. Embodiments of this method form the subject matter of dependent claims 2-8.

    [0010] In another example, a system is described as defined in independent claim 9. Embodiments of this system form the subject matter of dependent claims 10-15.

    [0011] The features, functions, and advantages that have been discussed can be achieved independently in various examples or may be combined in yet other examples further details of which can be seen with reference to the following description and drawings.

    BRIEF DESCRIPTION OF THE FIGURES



    [0012] The novel features believed characteristic of the illustrative examples are set forth in the appended claims. The illustrative examples, however, as well as a preferred mode of use, further objectives and descriptions thereof, will best be understood by reference to the following detailed description of an illustrative example of the present disclosure when read in conjunction with the accompanying drawings, wherein:

    Figure 1 is a block diagram illustrating a system, according to an example implementation.

    Figure 2 is a block diagram illustrating a device housing both the acceleration sensor and the force sensor, according to an example implementation.

    Figure 3 is a conceptual illustration of the pushback vehicle and the aircraft at pushback from the terminal, according to an example implementation.

    Figure 4 is a conceptual diagram of movement of the aircraft from a perspective of the aircraft, according to an example implementation.

    Figure 5 illustrates an example placement location of the force sensor and the acceleration sensor, according to an example implementation.

    Figure 6 illustrates an example placement of the force sensor on the rod, according to an example implementation.

    Figure 7 illustrates an example placement of the device housing both the acceleration sensor and the force sensor positioned on the rod, according to an example implementation.

    Figure 8 shows a flowchart of an example method of determining the total mass of the aircraft at pushback, according to an example implementation.

    Figure 9 shows a flowchart of another example method of determining the total mass of the aircraft at pushback, according to an example implementation.

    Figure 10 shows a flowchart of an example method for use with the method shown in Figure 9, according to an example implementation.

    Figure 11 shows a flowchart of another example method for use with the method shown in Figure 9, according to an example implementation.

    Figure 12 shows a flowchart of another example method for use with the method shown in Figure 9, according to an example implementation.

    Figure 13 shows a flowchart of the inventive method for use with the method shown in Figure 9.

    Figure 14 shows a flowchart of the inventive method of determining the coefficient of static friction.

    Figure 15 shows a flowchart of the inventive method.

    Figure 16 is a block diagram illustrating an example of the computing device, according to an example implementation.


    DETAILED DESCRIPTION



    [0013] Disclosed examples will now be described more fully hereinafter with reference to the accompanying drawings, in which some, but not all of the disclosed examples are shown. Indeed, several different examples may be described and should not be construed as limited to the examples set forth herein. Rather, these examples are described so that this disclosure will be thorough and complete and will fully convey the scope of the disclosure to those skilled in the art.

    [0014] Example systems and methods describe a process of how a total mass of an aircraft can be determined at pushback of the aircraft from the terminal, or while moving the aircraft in any scenario (e.g., moving the aircraft to or from a de-icing area). Sensors on a pushback vehicle can measure a number of variables useful for calculation in an equation of motion to arrive at the total mass of the aircraft. Instead of weighing all cargo and passengers/crew separately, which is not practical, the total mass of the aircraft can be calculated directly once fully loaded. In this way, a more accurate value for the total mass can be produced. A more accurate mass value, in turn, allows any trajectory planning system to plan a more optimal route that is more fuel efficient, as a most cost-optimal trajectory depends on aircraft mass. In addition, the calculated mass can be used to validate or note discrepancies with estimated weight used to calculate fuel burn, and provide a warning when a difference is beyond an error margin, for example.

    [0015] Referring now to the Figures, Figure 1 is a block diagram illustrating a system 100, according to an example implementation. The system 100 includes a pushback vehicle 102 coupled to an acceleration sensor 104 and a force sensor 106. The system 100 also includes a computing device 108 having one or more processors to determine a total mass of an aircraft 110 at pushback of the aircraft 110 from a terminal.

    [0016] The pushback vehicle 102 can take many forms, and may include an airplane tug or other type of vehicle that may pull or push the aircraft 110. The acceleration sensor 104, the force sensor 106, and the computing device 108 may be positioned on the pushback vehicle 102, in some examples. Additional configurations are described below.

    [0017] The acceleration sensor 104 determines an acceleration of the pushback vehicle 102 during pushback of the aircraft 110.

    [0018] The force sensor 106 determines a pushback force applied by the pushback vehicle 102 during pushback of the aircraft 110. In one example, the force sensor 106 includes a strain gauge. In another example, the force sensor 106 includes a pressure sensor as well.

    [0019] The computing device 108 is described more fully below with reference to Figure 16. The computing device 108 is communicatively coupled to the acceleration sensor 104 and the force sensor 106. In one example, the computing device 108 is directed wired to the acceleration sensor 104 and the force sensor 106. In another example, the computing device 108 is wirelessly connected to the acceleration sensor 104 and the force sensor 106.

    [0020] In examples, the computing device 108 has one or more processors to determine a total mass of the aircraft 110 at pushback based on the pushback force received from the force sensor 106, the acceleration of the pushback vehicle 102 during pushback or while moving the aircraft received from the acceleration sensor 104, and a coefficient of static friction between tires of the aircraft 110 and a surface on which the aircraft 110 moves. The computing device 108 may output the total mass of the aircraft 110 to an onboard aircraft computer 112, and/or to an airline operator 114. The onboard aircraft computer 112 and/or the airline operator 114 may use the total mass of the aircraft 110 to determine an optimal trajectory or to determine modifications to an assigned trajectory for more optimal fuel usage, for example.

    [0021] Figure 2 is a block diagram illustrating a device 116 housing both the acceleration sensor 104 and the force sensor 106, according to an example implementation. The device 116 further includes a wireless transmitter 118 to transmit data including the acceleration of the pushback vehicle 102 during pushback of the aircraft 110 and the pushback force applied by the pushback vehicle 102 during pushback of the aircraft 110 to the computing device 108, for example. In one example, the device 116 may be positioned on the pushback vehicle 102. Additional configurations are described below.

    [0022] Figure 3 is a conceptual illustration of the pushback vehicle 102 and the aircraft 110 at pushback from the terminal, according to an example implementation. The illustration in Figure 3 is conceptual and shows how to determine the total mass of the aircraft 110 at pushback by calculating the total mass of the aircraft 110 fully loaded and ready for take-off. At pushback, both the pushback vehicle 102 and the aircraft 110 move backward away from the terminal (e.g., in a rightward direction as shown in Figure 3). The pushback vehicle 102 is connected to the aircraft 110 through a rod 120, and thus, movement of the pushback vehicle 102 and the aircraft 110 is at equal speeds. Both of the pushback vehicle 102 and the aircraft 110 will also have the same acceleration (a), speed (s), and cover the same distance (d).

    [0023] Figure 4 is a conceptual diagram of movement of the aircraft 110 from a perspective of the aircraft 110, according to an example implementation. Figure 4 illustrates a free-body diagram, where an unknown mass (m) of the aircraft 110 that is accelerated with acceleration (a) has three forces acting on it at any time during pushback that include FPushback, FAero, and FStaticFriction.

    [0024] The FPushback force is the pushing force of the pushback vehicle 102. For example, FPushback is the force the pushback vehicle 102 generates to move the aircraft 110, and this variable is unknown and will be measured with the force sensor 106.

    [0025] The FAero force includes aerodynamic forces acting as drag on the aircraft 110 due to the movement. For example, FAero is a force of drag generated due to speed of the aircraft 110 and subsequently generated drag between air and aircraft surface. However, as FAero is proportional to a squared speed (s2), and the pushback speed necessarily being very low (e.g., a constant acceleration on the order of about 0.1 to 0.5 m/s), this force is negligible and can be set to zero (e.g., s2=(0.5 m/s)2=0.25 (m/s)2 and speed values of less than 1 m/s further amplify this negligibility). Furthermore, even in bad weather conditions with high winds, FAero would be negligible because airplanes are designed to be aerodynamically efficient. Alternatively, FAero would be negligible as compared to the force of static friction, and thus, FAero can be ignored. The larger the aircraft, the more negligible FAero is due to the force of static friction being larger.

    [0026] The FStaticFriction force is the force due to static friction between tires 122 of the aircraft 110 and a surface on which the aircraft 110 moves (e.g., the concrete floor). For example, FStaticFriction is a sum of forces acting on the tires 122 of the aircraft 110, which act against a direction of motion. Static friction is dependent on the mass multiplied by gravitational acceleration and a constant, µ0. The constant µ0 is called the static friction coefficient and depends on a corresponding surfaces' geometry and any potential lubricating liquid (e.g., rain or water) or lubricating solid (e.g., ice crystals or snow) between the surface and the tires 122. The static friction coefficient can be found within standard literature or is a constant known to a manufacturer of the tires 122, and therefore also known to the aircraft manufacturer. The static friction coefficient may be dependent on a material of the tire, and/or dependent on the surface on which the tire moves as well.

    [0027] From the free-body diagram shown in Figure 4, an equation of motion can be deduced from Newton's 2nd law of motion in which any object with a mass m (e.g., the aircraft 110), being accelerated with acceleration a, is equal to a sum of forces acting on the object. In this example, the FPushback acts in a direction opposite FAero and FStaticFriction. With FAero being proportional to the squared speed s2 and the system moving with a low speed (e.g., <1 m/s) during pushback, FAero is close to 0 and therefore negligible. The equation of motion is solved for the unknown mass m, as shown below:





    In the equation above, m is the total mass of the aircraft 110, FPushback is the pushback force, a is the acceleration of the pushback vehicle 102 during pushback, g is acceleration due to gravity, and µ0 is the coefficient of static friction between the tires of the aircraft 110 and the surface on which the aircraft moves.

    [0028] At this point, to calculate the mass m, only the pushback force and acceleration during pushback are needed. The static friction coefficient is known from the tire manufacturer for different weather conditions. In some examples, the coefficient of static friction between tires of the aircraft 110 and the surface on which the aircraft 110 moves is further based on a weather condition. For wet surfaces, the coefficient of static friction will differ as compared to dry surfaces. The two unknown values of the pushback force and acceleration during pushback can be measured using sensors on the pushback vehicle 102.

    [0029] In the example shown in Figure 3, the pushback vehicle 102 operates to pushback the aircraft 110 from a terminal prior to take-off, and the total mass of the aircraft can be determined at that time. However, in other examples, the pushback vehicle 102 may move the aircraft 110 in many other scenarios and determine the total mass of the aircraft 110 while moving the aircraft 110. As one example, the pushback vehicle 102 may move the aircraft 110 to or from a de-icing area, and determine the total mass of the aircraft 110 at that time. As another example, the pushback vehicle 102 may move the aircraft 110 into or out of a maintenance hangar, and the total mass of the aircraft 110 may be determined at that time. Thus, the pushback vehicle 102 may move or pushback the aircraft 110 in many scenarios, and movement of the aircraft 110 by the pushback vehicle 102 is described as "pushback" to indicate that the pushback vehicle 102 pushes (rather than pulls) the aircraft 110.

    [0030] Furthermore, in some examples, depending on when the total mass is determined, the total mass of the aircraft 110 can be determined for the aircraft 110 fully loaded and ready for take-off, or for the aircraft 110 empty to establish a dry weight or a weight change due to an aircraft configuration change (e.g., such as changing an interior or swapping out engines).

    [0031] Figures 5-7 illustrate example placement locations of the force sensor 106 and the acceleration sensor 104, according to an example implementation. In Figure 5, the acceleration sensor 104 is positioned on the pushback vehicle 102 to capture an acceleration in the pushback direction. This acceleration is used as the acceleration a in the equations above. The force sensor 106 is positioned proximal to a connection point of the rod 120 and the pushback vehicle 102. The rod 120 may be an aircraft coupler, and the force sensor 106 can be positioned on the pushback vehicle 102, on the rod 120, or on a connector between the pushback vehicle 102 and the rod 120, for example. The force sensor 106 can then measure or determine the force transferred through the rod 120 onto the aircraft 110. This force is used as the FPushback value in the equation above.

    [0032] Figure 6 illustrates an example placement of the force sensor 106 on the rod 120, according to an example implementation. In some examples, the acceleration sensor 104 may alternatively or additionally be positioned on the rod 120.

    [0033] Figure 7 illustrates an example placement of the device 116 housing both the acceleration sensor 104 and the force sensor 106 positioned on the rod 120, according to an example implementation. In any of these examples, the acceleration sensor 104 and the force sensor 106 are easily accessible for maintenance or replacement.

    [0034] Thus, within examples, the acceleration can be determined by placement of the acceleration sensor 104 anywhere on the pushback vehicle 102, or on the rod 120 that is connected to the pushback vehicle 102 and moves at the same speed as the pushback vehicle 102. The acceleration sensor 104 should be aligned into the direction of pushback.

    [0035] As mentioned above, both the acceleration sensor 104 and the force sensor 106 are in communication with the computing device 108, which may be positioned on the pushback vehicle 102, and to which the acceleration sensor 104 and the force sensor 106 transmit logged data.

    [0036] Figure 8 shows a flowchart of an example method 150 of determining the total mass of the aircraft 110 at pushback or during movement of the aircraft 110, according to an example implementation. Method 150 shown in Figure 8 presents an example of a method that could be used with the system 100 or the computing device 108, shown in Figure 1, for example. Further, devices or systems may be used or configured to perform logical functions presented in Figure 8. In some instances, components of the devices and/or systems may be configured to perform the functions such that the components are actually configured and structured (with hardware and/or software) to enable such performance. In other examples, components of the devices and/or systems may be arranged to be adapted to, capable of, or suited for performing the functions, such as when operated in a specific manner. Method 150 may include one or more operations, functions, or actions as illustrated by one or more of blocks 152-168. Although the blocks are illustrated in a sequential order, these blocks may also be performed in parallel, and/or in a different order than those described herein. Also, the various blocks may be combined into fewer blocks, divided into additional blocks, and/or removed based upon the desired implementation.

    [0037] It should be understood that for this and other processes and methods disclosed herein, flowcharts show functionality and operation of one possible implementation of present examples. In this regard, each block may represent a module, a segment, or a portion of program code, which includes one or more instructions executable by a processor for implementing specific logical functions or steps in the process. The program code may be stored on any type of computer readable medium or data storage, for example, such as a storage device including a disk or hard drive. Further, the program code can be encoded on a computer-readable storage media in a machine-readable format, or on other non-transitory media or articles of manufacture. The computer readable medium may include non-transitory computer readable medium or memory, for example, such as computer-readable media that stores data for short periods of time like register memory, processor cache and Random Access Memory (RAM). The computer readable medium may also include non-transitory media, such as secondary or persistent long term storage, like read only memory (ROM), optical or magnetic disks, compact-disc read only memory (CD-ROM), for example. The computer readable media may also be any other volatile or non-volatile storage systems. The computer readable medium may be considered a tangible computer readable storage medium, for example.

    [0038] In addition, each block in Figure 8, and within other processes and methods disclosed herein, may represent circuitry that is wired to perform the specific logical functions in the process. Alternative implementations are included within the scope of the examples of the present disclosure in which functions may be executed out of order from that shown or discussed, including substantially concurrent or in reverse order, depending on the functionality involved, as would be understood by those reasonably skilled in the art.

    [0039] At block 152, once the aircraft 110 is cleared by apron control for pushback and the pilot gives the pushback vehicle 102 clearance to do so, the acceleration sensor 104 and the force sensor 106 are switched on. Following, at block 154, the method 150 starts logging measurement data. The pushback then commences by the pushback vehicle 102, as shown at block 156. Data logging stops once the pushback is complete, as shown at block 158.

    [0040] The measurement data is provided to the computing device 108, as shown at block 160. The measurement data can be provided as being logged, and/or all at once when logging is completed in a batch process.

    [0041] Then, in the computing device 108, a number of calculations are performed. First, in the acceleration data, a time window t1 to t2 is determined, in which the acceleration is constant or substantially constant, as shown at block 162. A constant acceleration is needed to also be able to receive or determine a constant pushback force. To determine the time window, a first timepoint is determined where acceleration was greater than zero and then a second timepoint is determined having a same acceleration to establish a constant acceleration over the time period. In some examples, at least a minimum time frame is required to be elapsed between the first timepoint and the second timepoint to enable pushback to have traversed some distance.

    [0042] Following, as shown at block 164, using the determined time window between t1 and t2, the pushback force is retrieved from the data. For example, a force data point from the pushback force data is selected at a timepoint between the first timepoint and the second timepoint (e.g., between t1 and t2). When the acceleration is constant, the force is also constant.

    [0043] Next, as shown at block 166, the coefficient of static friction is determined from tire manufacturer data, and may be dependent on weather conditions. For example, if the surface or tarmac is dry, µ0 = µdry; if the surface or tarmac is wet, µ0 = µwet; if the surface or tarmac is snowy, µ0 = µsnow. Any number of different coefficients of static friction may be used or set for different weather conditions.

    [0044] All values obtained are then inserted into the equation above to solve for the mass m of the aircraft 110, as shown at block 168.

    [0045] Figure 9 shows a flowchart of another example method 200 of determining the total mass of the aircraft 110 at pushback, according to an example implementation. Method 200 shown in Figure 9 presents an example of a method that could be used with the system 100 or the computing device 108 shown in Figure 1, for example. Further, devices or systems may be used or configured to perform logical functions presented in Figure 9. Method 200 may include one or more operations, functions, or actions as illustrated by one or more of blocks 202-206. Although the blocks are illustrated in a sequential order, these blocks may also be performed in parallel, and/or in a different order than those described herein. Also, the various blocks may be combined into fewer blocks, divided into additional blocks, and/or removed based upon the desired implementation.

    [0046] At block 202, the method 200 includes determining an acceleration of the pushback vehicle 102 while moving the aircraft 110. At block 204, the method 200 includes determining a pushback force applied by the pushback vehicle 102 while moving the aircraft 110. At block 206, the method 200 includes determining a total mass of the aircraft 110 based on the pushback force, the acceleration of the pushback vehicle 102 during pushback, and a coefficient of static friction between tires 122 of the aircraft 110 and a surface on which the aircraft 110 moves. In these examples, determining the total mass of the aircraft 110 at pushback comprises calculating the total mass of the aircraft 110 fully loaded and ready for take-off.

    [0047] Figure 10 shows a flowchart of an example method for use with the method 200, according to an example implementation. At block 208, functions include determining the coefficient of static friction between tires 122 of the aircraft 110 and the surface on which the aircraft 110 moves based on a weather condition. Block 208 may be inserted between block 204 and block 206 in the flowchart of Fig. 9.

    [0048] Figure 11 shows a flowchart of another example method for use with the method 200, according to an example implementation. At block 210, functions include causing an alarm based on the determined total mass of the aircraft 110 being over, by a threshold amount, an estimated mass used for a fuel burn calculation. For instance, if the total mass of the aircraft is over 5% of the estimated mass (as determined using established weights per passenger and luggage) used for the fuel burn calculation, then an alarm can be provided to airline operators to modify a trajectory of the aircraft for better fuel burn. Block 210 may be inserted after block 206 in the flowchart of Fig. 9.

    [0049] Figure 12 shows a flowchart of another example method for use with the method 200, according to an example implementation. The method shown in Figure 12 is useful for selecting acceleration and force data points within logged data. At block 212, functions include receiving pushback force data, and at block 214 functions include receiving acceleration data of the pushback vehicle 102 while moving the aircraft 110. At block 216, functions include determining a first timepoint where acceleration was greater than zero, and at block 218 functions include determining a second timepoint having a same acceleration to establish a constant acceleration. At block 220, functions include retrieving a force data point from the pushback force data at a timepoint between the first timepoint and the second timepoint, and at block 222, functions include using the constant acceleration and the force data point to determine the total mass of the aircraft 110.

    [0050] Figure 13 shows a flowchart of the inventive method for use with the method 200, according to an example implementation. The method shown in Figure 13 is useful for determining the coefficient of static friction. At block 224, functions include applying a known mass to the aircraft 110, and at blocks 226 and 228, functions include determining a second acceleration of the pushback vehicle 102 while moving the aircraft 110 with the known mass and determining a second pushback force applied by the pushback vehicle 102 while moving the aircraft 110 with the known mass. At block 230, functions include determining the coefficient of static friction between tires 122 of the aircraft 110 and a surface on which the aircraft 110 moves based on the known mass, the first acceleration, the first pushback force, the second acceleration, and the second pushback force. Blocks 224-230 may be inserted between block 204 and block 206 in the flowchart of Fig. 9.

    [0051] Within examples, determining the total mass of the aircraft 110 at pushback can be calculated using the following equation:

    where m is the total mass of the aircraft 110, FPushback is the pushback force, a is the acceleration of the pushback vehicle during pushback, g is acceleration due to gravity, and µ0 is the coefficient of static friction between the tires 122 of the aircraft 110 and the surface on which the aircraft 110 moves.

    [0052] Figure 14 shows a flowchart of the inventive method 250 of determining the coefficient of static friction, according to an example implementation. Method 250 shown in Figure 14 presents an example of a method that could be used with the system 100 or the computing device 108 shown in Figure 1, for example. Further, devices or systems may be used or configured to perform logical functions presented in Figure 14. Method 250 may include one or more operations, functions, or actions as illustrated by one or more of blocks 252-262. Although the blocks are illustrated in a sequential order, these blocks may also be performed in parallel, and/or in a different order than those described herein. Also, the various blocks may be combined into fewer blocks, divided into additional blocks, and/or removed based upon the desired implementation.

    [0053] At block 252, the method 250 includes determining a first acceleration of the pushback vehicle 102 while moving the aircraft 110. At block 254, the method 250 includes determining a first pushback force applied by the pushback vehicle 102 while moving the aircraft 110. At block 256, the method 250 includes applying a known mass to the aircraft 110. At block 258, the method 250 includes determining a second acceleration of the pushback vehicle 102 while moving the aircraft 110 with the known mass. At block 260, the method 250 includes determining a second pushback force applied by the pushback vehicle 102 while moving the aircraft 110 with the known mass. At block 262, the method 250 includes determining a coefficient of static friction between tires 122 of the aircraft 110 and a surface on which the aircraft 110 moves based on the known mass, the first acceleration, the first pushback force, the second acceleration, and the second pushback force.

    [0054] Within examples, the method 250 includes determining the coefficient of static friction using the following equation:

    where Δm is the known mass, FPushback1 is the first pushback force, FPushback2 is the second pushback force, a1 is the first acceleration, a2 is the second acceleration, g is acceleration due to gravity, and µ0 is the coefficient of static friction.

    [0055] Figure 15 shows a flowchart of the inventive method for use with the method 250. At block 264, functions include iteratively solving for values for the coefficient of static friction, µ0, until convergence. Block 264 may be a sub-block of block 262 in the flowchart of Fig. 14.

    [0056] Using the method 250 to determine the coefficient of static friction would allow the determination of this constant without relying on data from a tire manufacturer. In an illustrative example of the method 250, initially an aircraft with any mass is pushed back while FPushback and the acceleration is measured by the force sensor 106 and the acceleration sensor 104. Then, the same aircraft is loaded with a known mass (e.g. 100 kg) and the process is repeated. Once more, FPushback and the acceleration are gauged. Therefore, at this point, the known variables are: FPushback1, FPushback2, acceleration1 (a1), acceleration2 (a2), and Δm = m2 - m1 (since the aircraft is heavier by 100 kg).

    [0057] The equations below outline the process for determining Δm:







    [0058] As shown in the equations above, only µ0 is an unknown. To still solve for µ0, a numeric solver can be used to solve the equation by iteratively inserting values for µ0 until a value is found that solves the equation. An example numeric solver includes Newton's method:



    [0059] To apply this method, the equation for Δm is rearranged to solve for zero, as shown below:



    [0060] Then the first derivative for µ0 is determined as:



    [0061] Knowing that typical values for µ0 for rubber on tarmac are around 0.8, the numeric solver could start with an initial µ0 = 0.4 and iterate until convergence.

    [0062] Example systems and methods described herein include a deterministic approach to calculating the total mass of the aircraft 110, instead of using estimates that are unable to be verified. Existing systems simply use a standard weight value for each passenger. However, there is no option to determine how good the estimates are compared to actual weights.

    [0063] In some examples, the calculation of the total mass of the aircraft 110 can have a variance based on the coefficient of static friction that is used. Even though tire manufacturers will provide values for tires for different weather conditions, these values may include an error component in a range of about 0.05 (e.g., a coefficient of static friction for a tire on dry tarmac is estimated at 0.8, but due to weather circumstances and the surface of the tarmac, this may vary by an example of 0.05).

    [0064] As example error calculation or error estimation is shown below using an expected error of Δµ0 = 0.05 as calculated by



    [0065] An equation for error estimation is as follows:



    [0066] The derivative of function (f) for µ0 is as follows:



    [0067] For this calculation, parameters were used as follows: acceleration of a=0.4 m/s2, mass of m = 251,290 kg, gravitational acceleration g = 9.81 m/s2, µ0 = 0.8, and pushback force of FPushback = 100500 N. Thus, a possible error may be in a range of Δm = 730 kg, which is negligible given the mass of the aircraft 110.

    [0068] Using standard aircraft mass determinations includes calculations based on a standard weight assumption per passenger around 82 kg/person, plus an extra 5 kg for carry-on luggage. It has been estimated that such parameters for standard calculations can be off by as much as 14 kg/pax. With a lowest seating capacity of 354 (3-class setting) and a highest of 442 (2-class setting) as contemplated for the new Boeing 777-9 aircraft, the error for standard mass determinations may be in a range of 4950 kg (354 passengers) to 6190 kg (442 passengers). Therefore, the error estimate of the example methods and systems described herein for a deterministic approach to calculating the total mass of the aircraft 110 yields smaller error ranges. These lower error ranges, when implemented in trajectory optimization solutions, can generate more cost-optimal trajectories and step climbs throughout cruise flight.

    [0069] In further examples, additional benefits for accurate mass determinations can be achieved in regards to checked baggage weight. Currently, the weight of checked baggage cargo at the gate is not used as a weighing scale is not calibrated often enough to assure accuracy. Therefore, the weight values are not used for the calculation, but rather estimates are used (as with passengers). Of course, weight of each checked bag or luggage can vary. Example methods and systems described herein circumvents necessity of weighing checked baggage, as the entire aircraft's mass is determined directly, during a standard process (pushback) that is always performed. Moreover, the example systems are not stationary, and will not need to be implemented at every gate, but can be realized on every pushback vehicle 102.

    [0070] Note that in some examples, while the deterministic methods are able to yield the entire aircraft's mass, the checked baggage estimate can nevertheless be used for refueling calculations. This will provide further safety checks. The example methods described herein can be used for non-safety trajectory optimization.

    [0071] In further examples and enhancements, the aircraft 110 could be refueled with a known base amount of fuel and then the example deterministic methods described herein may be used to determine the total mass of the aircraft 110. Based on this mass, an ideal amount of fuel could then be calculated and further added.

    [0072] Figure 16 is a block diagram illustrating an example of the computing device 108, according to an example implementation. The computing device 108 may be used to perform functions of methods shown in Figures 8-15. The computing device 108 has a processor(s) 170, and also a communication interface 172, data storage 174, an output interface 176, and a display 178 each connected to a communication bus 180. The computing device 108 may also include hardware to enable communication within the computing device 108 and between the computing device 108 and other devices (not shown). The hardware may include transmitters, receivers, and antennas, for example.

    [0073] The communication interface 172 may be a wireless interface and/or one or more wireline interfaces that allow for both short-range communication and long-range communication to one or more networks or to one or more remote devices. Such wireless interfaces may provide for communication under one or more wireless communication protocols, such as Very High Frequency (VHF) Data link (VDL), VDL Mode 2, Aircraft Communications Addressing and Reporting System (ACARS) digital communications over VHF radio and satellite communications (SATCOM), Bluetooth, WiFi (e.g., an institute of electrical and electronic engineers (IEEE) 802.11 protocol), Long-Term Evolution (LTE), cellular communications, near-field communication (NFC), and/or other wireless communication protocols. Such wireline interfaces may include aircraft data buses such as Aeronautical Radio, Incorporated (ARINC) 429, 629, or 664 based interfaces, Ethernet interface, a Universal Serial Bus (USB) interface, or similar interface to communicate via a wire, a twisted pair of wires, a coaxial cable, an optical link, a fiber-optic link, or other physical connection to a wireline network. Thus, the communication interface 172 may be configured to receive input data from one or more devices, and may also be configured to send output data to other devices.

    [0074] The communication interface 172 may also include a user-input device, such as a keyboard or mouse, for example.

    [0075] The data storage 174 may include or take the form of one or more computer-readable storage media that can be read or accessed by the processor(s) 170. The computer-readable storage media can include volatile and/or non-volatile storage components, such as optical, magnetic, organic or other memory or disc storage, which can be integrated in whole or in part with the processor(s) 170. The data storage 174 is considered non-transitory computer readable media. In some examples, the data storage 174 can be implemented using a single physical device (e.g., one optical, magnetic, organic or other memory or disc storage unit), while in other examples, the data storage 174 can be implemented using two or more physical devices.

    [0076] The data storage 174 thus is a non-transitory computer readable storage medium, and executable instructions 182 are stored thereon. The instructions 182 include computer executable code. When the instructions 182 are executed by the processor(s) 170, the processor(s) 170 are caused to perform functions. Such functions include determining a total mass of the aircraft 110 at pushback based on the pushback force, the acceleration of the pushback vehicle 102 during pushback, and a coefficient of static friction between tires 122 of the aircraft 110 and a surface on which the aircraft 110 moves.

    [0077] The processor(s) 170 may be a general-purpose processor or a special purpose processor (e.g., digital signal processors, application specific integrated circuits, etc.). The processor(s) 170 may receive inputs from the communication interface 172, and process the inputs to generate outputs that are stored in the data storage 174 and output to the display 178. The processor(s) 170 can be configured to execute the executable instructions 182 (e.g., computer-readable program instructions) that are stored in the data storage 174 and are executable to provide the functionality of the computing device 108 described herein.

    [0078] The output interface 176 outputs information to the display 178 or to other components as well. Thus, the output interface 176 may be similar to the communication interface 172 and can be a wireless interface (e.g., transmitter) or a wired interface as well. The output interface 176 may send information about the determined total mass of the aircraft to the airline operator 114 and/or to the onboard aircraft computer 112, for example.

    [0079] By the term "substantially" or "about" used herein, it is meant that the recited characteristic, parameter, or value need not be achieved exactly, but that deviations or variations, including for example, tolerances, measurement error, measurement accuracy limitations and other factors known to skill in the art, may occur in amounts that do not preclude the effect the characteristic was intended to provide.


    Claims

    1. A method (200) of determining a total mass of an aircraft (110) comprising:

    determining (202) an acceleration of a pushback vehicle (102) while moving the aircraft (110);

    determining (204) a pushback force applied by the pushback vehicle (102) while moving the aircraft (110); and

    determining (206) the total mass of the aircraft (110) based on the pushback force, the acceleration of the pushback vehicle (102), and a coefficient of static friction between tires (122) of the aircraft (110) and a surface on which the aircraft (110) moves;

    wherein determining the acceleration of the pushback vehicle (102) while moving the aircraft (110) comprises determining a first acceleration, and wherein determining the pushback force applied by the pushback vehicle (102) while moving the aircraft (110) comprises determining a first pushback force, and wherein the method further comprises:

    applying (224) a known mass to the aircraft (110);

    determining (226) a second acceleration of the pushback vehicle (102) while moving the aircraft (110) with the known mass;

    determining (228) a second pushback force applied by the pushback vehicle (102) while moving the aircraft (110) with the known mass; and

    determining (230) the coefficient of static friction between tires (122) of the aircraft (110) and a surface on which the aircraft (110) moves based on the known mass, the first acceleration, the first pushback force, the second acceleration, and the second pushback force.


     
    2. The method (200) of claim 1, wherein determining the total mass of the aircraft (110) comprises calculating the total mass of the aircraft (110) fully loaded and ready for take-off.
     
    3. The method (200) of claim 1 or 2, further comprising:
    determining (208) the coefficient of static friction between tires (122) of the aircraft (110) and the surface on which the aircraft (110) moves based on a weather condition.
     
    4. The method (200) of any one of claims 1-3, further comprising:
    causing (210) an alarm based on the determined total mass of the aircraft (110) being over, by a threshold amount, an estimated mass used for a fuel burn calculation.
     
    5. The method (200) of any one of claims 1-4, further comprising:

    receiving (212) pushback force data;

    receiving (214) acceleration data of the pushback vehicle (102) while moving the aircraft (110);

    determining (216) a first timepoint where acceleration was greater than zero;

    determining (218) a second timepoint having a same acceleration to establish a constant acceleration;

    retrieving (220) a force data point from the pushback force data at a timepoint between the first timepoint and the second timepoint; and

    using (222) the constant acceleration and the force data point to determine the total mass of the aircraft (110).


     
    6. The method (200) of any one of claims 1-5, wherein determining the total mass of the aircraft (110) comprises determining the total mass of the aircraft (110) using the following equation:

    where m is the total mass of the aircraft (110), FPushback is the pushback force, a is the acceleration of the pushback vehicle (102), g is acceleration due to gravity, and µ0 is the coefficient of static friction between the tires (122) of the aircraft (110) and the surface on which the aircraft (110) moves.
     
    7. The method (250) of any one of claims 1-6, wherein determining the coefficient of static friction comprises using the following equation:

    where Δm is the known mass, FPushback1 is the first pushback force, FPushback2 is the second pushback force, a1 is the first acceleration, a2 is the second acceleration, g is acceleration due to gravity, and µ0 is the coefficient of static friction.
     
    8. The method (250) of claim 7, further comprising iteratively solving (264) for values for µ0 until convergence.
     
    9. A system (100) for determining a total mass of an aircraft (110) comprising:

    a pushback vehicle (102) coupled to an acceleration sensor (104) to determine an acceleration of the pushback vehicle (102) while moving the aircraft (110), and coupled to a force sensor (106) to determine a pushback force applied by the pushback vehicle (102) while moving the aircraft (110); and

    a computing device (108) having one or more processors to determine a total mass of the aircraft (110) based on the pushback force, the acceleration of the pushback vehicle (102), and a coefficient of static friction between tires (122) of the aircraft (110) and a surface on which the aircraft (110) moves by performing the method of claim 1.


     
    10. The system (100) of claim 9, wherein the acceleration sensor (104) is positioned on the pushback vehicle (102) to capture an acceleration in a pushback direction.
     
    11. The system (100) of claim 9 or 10, further comprising:
    a rod (120) between the pushback vehicle (102) and the aircraft (110), wherein the force sensor (106) is positioned proximal to a connection point of the rod (120) and the pushback vehicle (102).
     
    12. The system (100) of claim 9 or 10, further comprising:
    a rod (120) between the pushback vehicle (102) and the aircraft (110), wherein the force sensor (106) is positioned on the rod (120).
     
    13. The system (100) of any one of claims 9-12, further comprising a wireless transmitter (118) to transmit data including the acceleration of the pushback vehicle (102) while moving the aircraft (110) and the pushback force applied by the pushback vehicle (102) while moving the aircraft (110) to the computing device (108).
     
    14. The system (100) of claim 9, wherein the pushback vehicle (102) includes an airplane tug.
     
    15. The system (100) of claim 9, further comprising a device housing both the acceleration sensor and the force sensor.
     


    Ansprüche

    1. Verfahren (200) zur Bestimmung der Gesamtmasse eines Flugzeugs (110), wobei das Verfahren Folgendes umfasst:

    Bestimmen (202) einer Beschleunigung eines Rückstoßfahrzeugs (102) während des Bewegens des Flugzeugs (110);

    Bestimmen (204) einer Rückstoßkraft, die während des Bewegens des Flugzeugs (110) von dem Rückstoßfahrzeug (102) ausgeübt wird; und

    Bestimmen (206) einer Gesamtmasse des Flugzeugs (110) basierend auf der Rückstoßkraft, der Beschleunigung des Rückstoßfahrzeugs (102) und einem Haftreibungskoeffizienten zwischen den Reifen (122) des Flugzeugs (110) und einer Oberfläche, auf der das Flugzeug (110) sich bewegt;

    wobei das Bestimmen der Beschleunigung des Rückstoßfahrzeugs (102) während des Bewegens des Flugzeugs (110) das Bestimmen einer ersten Beschleunigung umfasst, und wobei das Bestimmen der während des Bewegens des Flugzeugs (110) von dem Rückstoßfahrzeug ausgeübte Rückstoßkraft das Bestimmen einer ersten Rückstoßkraft umfasst, und wobei das Verfahren weiterhin Folgendes umfasst:

    Aufbringen (224) einer bekannten Masse auf das Flugzeug (110);

    Bestimmen (226) einer zweiten Beschleunigung des Rückstoßfahrzeugs (102) während des Bewegens des Flugzeugs (110) mit der bekannten Masse;

    Bestimmen (228) einer zweiten Rückstoßkraft, die während des Bewegens des Flugzeugs (110) mit der bekannten Masse von dem Rückstoßfahrzeug (102) ausgeübt wird; und

    Bestimmen (230) des Haftreibungskoeffizienten zwischen den Reifen (122) des Flugzeugs (110) und einer Oberfläche, auf der das Flugzeug (110) sich bewegt, basierend auf der bekannten Masse, der ersten Beschleunigung, der ersten Rückstoßkraft, der zweiten Beschleunigung und der zweiten Rückstoßkraft.


     
    2. Verfahren (200) nach Anspruch 1, wobei das Bestimmen der Gesamtmasse des Flugzeugs (110) das Berechnen der Gesamtmasse des Flugzeugs (110), das vollständig beladen und startbereit ist, umfasst.
     
    3. Verfahren (200) nach Anspruch 1 oder 2, wobei das Verfahren weiterhin Folgendes umfasst:
    Bestimmen (208) des Haftreibungskoeffizienten zwischen den Reifen (122) des Flugzeugs (110) und der Oberfläche, auf der das Flugzeug (110) sich bewegt, basierend auf einer Wetterbedingung.
     
    4. Verfahren (200) nach einem der Ansprüche 1 bis 3, das weiterhin Folgendes umfasst: Auslösen (210) eines Alarms, wenn die bestimmte Gesamtmasse des Flugzeugs (110) um einen Schwellenbetrag über einer geschätzten Masse liegt, die für eine Berechnung der Treibstoffverbrennung verwendet wurde.
     
    5. Verfahren (200) nach einem der Ansprüche 1 bis 4, das weiterhin Folgendes umfasst:

    Empfangen (212) von Daten über eine Rückstoßkraft;

    Empfangen (214) von Daten über die Beschleunigung des Rückstoßfahrzeugs (102) während des Bewegens des Flugzeugs (110);

    Bestimmen (216) eines ersten Zeitpunkts, an dem die Beschleunigung größer als Null war; Bestimmen (218) eines zweiten Zeitpunkts mit der selben Beschleunigung, um eine konstante Beschleunigung zu erzeugen;

    Abrufen (220) eines Kraftdatenpunkts aus den Daten über die Rückstoßkraft zu einem Zeitpunkt zwischen dem ersten Zeitpunkt und dem zweiten Zeitpunkt; und

    Verwenden (222) der konstanten Beschleunigung und des Kraftdatenpunkts, um die Gesamtmasse des Flugzeugs (110) zu bestimmen.


     
    6. Verfahren (200) nach einem der Ansprüche 1 bis 5, wobei das Bestimmen der Gesamtmasse des Flugzeugs (110) das Bestimmen der Gesamtmasse des Flugzeugs (110) unter Verwendung der folgenden Gleichung umfasst:

    wobei es sich bei m um die Gesamtmasse des Flugzeugs (110) handelt, bei FPushback um die Rückstoßkraft, bei a um die Beschleunigung des Rückstoßfahrzeugs (102), bei g um eine Beschleunigung wegen der Schwerkraft, und bei µ0 um den Haftreibungskoeffizienten zwischen den Reifen (122) des Flugzeugs (110) und einer Oberfläche, auf der das Flugzeug (110) sich bewegt.
     
    7. Verfahren (250) nach einem der Ansprüche 1 bis 6, wobei das Bestimmen des Haftreibungskoeffizienten die Verwendung der folgenden Gleichung umfasst:

    wobei es sich bei Δm um die bekannte Masse handelt, bei FPushback1 um die erste Rückstoßkraft, bei FPushback2 um die zweite Rückstoßkraft, bei a1 um die erste Beschleunigung, bei a2 um die zweite Beschleunigung, bei g um die Beschleunigung wegen der Schwerkraft, und bei µ0 um den Haftreibungskoeffizienten.
     
    8. Verfahren (250) nach Anspruch 7, das weiterhin ein iteratives Auflösen (264) nach Werten für µ0 bis zur Konvergenz umfasst.
     
    9. System (100) zur Bestimmung einer Gesamtmasse eines Flugzeugs (110), wobei das System Folgendes umfasst:

    ein Rückstoßfahrzeug (102), das mit einem Beschleunigungssensor (104) gekoppelt ist, um eine Beschleunigung des Rückstoßfahrzeugs (102) während der Bewegung des Flugzeugs (110) zu bestimmen, und das mit einem Kraftsensor (106) gekoppelt ist, um eine während der Bewegung des Flugzeugs (110) von dem Rückstoßfahrzeug ausgeübte Kraft zu bestimmen; und

    eine wenigstens einen Prozessor aufweisende Computervorrichtung (108) zum Bestimmen der Gesamtmasse des Flugzeugs (110) basierend auf der Rückstoßkraft, der Beschleunigung des Rückstoßfahrzeugs (102) und einem Haftreibungskoeffizienten zwischen den Reifen (122) des Flugzeugs (110) und einer Oberfläche, auf der das Flugzeug (110) sich bewegt, und zwar mittels Durchführung des Verfahrens nach Anspruch 1.


     
    10. System (100) nach Anspruch 9, wobei der Beschleunigungssensor (104) an dem Rückstoßfahrzeug (102) angeordnet ist, um eine Beschleunigung in einer Rückstoßrichtung zu erfassen.
     
    11. System (100) nach Anspruch 9 oder 10, das weiterhin Folgendes umfasst:
    eine Stange (120) zwischen dem Rückstoßfahrzeug (102) und dem Flugzeug (110), wobei der Kraftsensor (106) proximal zu einem Verbindungspunkt zwischen der Stange (120) und dem Rückstoßfahrzeug (102) angeordnet ist.
     
    12. System (100) nach Anspruch 9 oder 10, das weiterhin Folgendes umfasst:
    eine Stange (120) zwischen dem Rückstoßfahrzeug (102) und dem Flugzeug (110), wobei der Kraftsensor (106) an der Stange (120) angeordnet ist.
     
    13. System (100) nach einem der Ansprüche 9 bis 12, das weiterhin eine drahtlose Übertragungseinrichtung (118) umfasst, um Daten einschließlich der Beschleunigung des Rückstoßfahrzeugs (102) während der Bewegung des Flugzeugs (110) und der während der Bewegung des Flugzeugs (110) von dem Rückstoßfahrzeug (102) ausgeübten Rückstoßkraft an die Computervorrichtung (108) zu übertragen.
     
    14. System (100) nach Anspruch 9, wobei das Rückstoßfahrzeug (102) einen Flugzeugschlepper umfasst.
     
    15. System (100) nach Anspruch 9, das weiterhin eine Vorrichtung umfasst, welche sowohl den Beschleunigungssensor, als auch den Kraftsensor beherbergt.
     


    Revendications

    1. Procédé (200) de détermination de la masse totale d'un aéronef (110) comprenant :

    la détermination (202) de l'accélération d'un véhicule de refoulement (102) pendant le déplacement de l'aéronef (110), et

    la détermination (204) de la force de refoulement appliquée par le véhicule de refoulement (102) pendant le déplacement de l'aéronef (110) ; et

    la détermination (206) de la masse totale de l'aéronef (110) compte tenu de la force de refoulement, de l'accélération du véhicule de refoulement (102) et d'un coefficient de frottement statique entre les pneus (122) de l'aéronef (110) et la surface sur laquelle se déplace l'aéronef (110) ;

    ladite détermination de l'accélération du véhicule de refoulement (102) pendant le déplacement de l'aéronef (110) comprenant la détermination d'une première accélération, et ladite détermination de la force de refoulement appliquée par le véhicule de refoulement (102) pendant le déplacement de l'aéronef (110) comprenant la détermination d'une première force de refoulement, ledit procédé comprenant en outre :

    l'application (224) d'une masse connue sur l'aéronef (110) ;

    la détermination (226) d'une deuxième accélération du véhicule de refoulement (102) pendant le déplacement de l'aéronef (110) avec la masse connue ;

    la détermination (228) d'une deuxième force de refoulement appliquée par le véhicule de refoulement (102) pendant le déplacement de l'aéronef (110) avec la masse connue ; et

    la détermination (230) du coefficient de frottement statique entre les pneus (122) de l'aéronef (110) et la surface sur laquelle se déplace l'aéronef (110), compte tenu de la masse connue, de la première accélération, de la première force de refoulement, de la deuxième accélération et de la deuxième force de refoulement.


     
    2. Procédé (200) selon la revendication 1, dans lequel la détermination de la masse totale de l'aéronef (110) comprend le calcul de la masse totale de l'aéronef (110) totalement chargé et prêt au décollage.
     
    3. Procédé (200) selon la revendication 1 ou 2, comprenant en outre :
    la détermination (208) du coefficient de frottement statique entre les pneus (122) de l'aéronef (110) et la surface sur laquelle se déplace l'aéronef (110), compte tenu d'une condition météorologique.
     
    4. Procédé (200) selon l'une quelconque des revendications 1 à 3, comprenant en outre : le déclenchement (210) d'une alarme compte tenu du fait que la masse totale de l'aéronef (110) déterminée est supérieure, d'une quantité seuil, à une masse estimée servant à un calcul du carburant consommé.
     
    5. Procédé (200) selon l'une quelconque des revendications 1 à 4, comprenant en outre :

    la réception (212) de données de force de refoulement,

    la réception (214) de données d'accélération du véhicule de refoulement (102) pendant le déplacement de l'aéronef (110),

    la détermination (216) d'un premier instant où l'accélération était supérieure à zéro, la détermination (218) d'un deuxième instant présentant la même accélération afin d'établir une accélération constante,

    la récupération (220) d'un point de données de force à partir des données de force de refoulement à un instant compris entre le premier instant et le deuxième instant, et

    l'utilisation (222) de l'accélération constante et du point de données de force pour déterminer la masse totale de l'aéronef (110).


     
    6. Procédé (200) selon l'une quelconque des revendications 1 à 5, dans lequel la détermination de la masse totale de l'aéronef (110) comprend la détermination de la masse totale de l'aéronef (110) au moyen de l'équation suivante :

    m représente la masse totale de l'aéronef (110), FPushback représente la force de refoulement, a représente l'accélération du véhicule de refoulement (102), g représente l'accélération de la pesanteur, et µ0 représente le coefficient de frottement statique entre les pneus (122) de l'aéronef (110) et la surface sur laquelle se déplace l'aéronef (110).
     
    7. Procédé (250) selon l'une quelconque des revendications 1 à 6, dans lequel la détermination du coefficient de frottement statique comprend l'utilisation de l'équation suivante :

    où Δm représente la masse connue, FPushback1 représente la première force de refoulement, FPushback2 représente la deuxième force de refoulement, a1 représente la première accélération, a2 représente la deuxième accélération, g représente l'accélération de la pesanteur, et µ0 représente le coefficient de frottement statique.
     
    8. Procédé (250) selon la revendication 7, comprenant en outre un calcul itératif (264) des valeurs de µ0 pour atteindre la convergence.
     
    9. Système (100) de détermination de la masse totale d'un aéronef (110) comprenant :

    un véhicule de refoulement (102) couplé à un capteur accélérométrique (104) pour déterminer l'accélération du véhicule de refoulement (102) pendant le déplacement de l'aéronef (110), et couplé à un capteur d'effort (106) pour déterminer la force de refoulement appliquée par le véhicule de refoulement (102) pendant le déplacement de l'aéronef (110) ; et

    un dispositif informatisé (108) possédant un ou plusieurs processeurs pour déterminer la masse totale de l'aéronef (110) compte tenu de la force de refoulement, de l'accélération du véhicule de refoulement (102) et d'un coefficient de frottement statique entre les pneus (122) de l'aéronef (110) et la surface sur laquelle se déplace l'aéronef (110), en réalisant le procédé selon la revendication 1.


     
    10. Système (100) selon la revendication 9, dans lequel le capteur accélérométrique (104) est disposé sur le véhicule de refoulement (102) pour capter l'accélération dans la direction du refoulement.
     
    11. Système (100) selon la revendication 9 ou 10, comprenant en outre :
    une barre (120) entre le véhicule de refoulement (102) et l'aéronef (110), ledit capteur d'effort (106) étant disposé à proximité d'un point de raccord de la barre (120) et du véhicule de refoulement (102).
     
    12. Système (100) selon la revendication 9 ou 10, comprenant en outre :
    une barre (120) entre le véhicule de refoulement (102) et l'aéronef (110), ledit capteur d'effort (106) étant disposé sur la barre (120).
     
    13. Système (100) selon l'une quelconque des revendications 9 à 12, comprenant en outre un émetteur sans fil (118) destiné à transmettre des données, dont l'accélération du véhicule de refoulement (102) pendant le déplacement de l'aéronef (110) et la force de refoulement appliquée par le véhicule de refoulement (102) pendant le déplacement de l'aéronef (110), au dispositif informatisé (108).
     
    14. Système (100) selon la revendication 9, dans lequel le véhicule de refoulement (102) comprend un tracteur d'avion.
     
    15. Système (100) selon la revendication 9, comprenant en outre un dispositif abritant à la fois le capteur accélérométrique et le capteur d'effort.
     




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    Cited references

    REFERENCES CITED IN THE DESCRIPTION



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    Patent documents cited in the description