• 专利附录
  • 专利说明
  • 权利要求
  • 类似技术
  • 同族专利
  • 引用文献
  • 法律状态
  • 优先权
    • 专利摘要:
    The runway condition determined by an aircraft on the ground and provided to the aircraft on approach is not sufficient to account for any runway degradation that has occurred since the previous determination of this runway condition. The updating of this track condition on the basis of a simple comparison between a desired deceleration and a deceleration observed resulting from a degraded track is also unsatisfactory. The invention then provides for obtaining a local stopping distance according to a local runway condition characterizing a runway area on which the aircraft rolls during landing, this local stopping distance being estimated from local measurements made in the aircraft; to obtain a reference stopping distance according to a reference track state; and then comparing these two distances to each other to determine if the local track condition is more degraded than the reference track condition.
    公开号:FR3045197A1
    申请号:FR1562246
    申请日:2015-12-11
    公开日:2017-06-16
    发明作者:Erwan Le-Bouedec；Remi Morin；Jeremie Briere；Mathieu Reguerre；Nicolas Daniel
    申请人:Airbus Operations SAS；
    IPC主号:
    专利说明:

    Dans cette mise en œuvre, la valeur du coefficient est, d’une part, fonction de ladite différence relative AD, et, d’autre part, fonction de l’état de piste de référence. Bien entendu, l’un ou l’autre des critères peut être utilisé seul.
    En effet, sur une piste sèche (EPref=DRY), CoeffAD(t) = 0,1 si AD(t) e [3 ; 6[, alors que CoeffAD(t) = 1 si AD(t) e [16 ; 25[.
    De même, si AD(t) = 15, Coeff4D(t) = 0,4 lors que la piste est humide (EPref=WET), alors que CoeffAD(t) = 0,6 en cas de piste sèche. A noter qu’en variante à l’utilisation de la différence relative AD, la distance ôD peut être utilisée. Dans ce cas, les valeurs seuils de la première colonne de la table ci-dessus peuvent être ajustées, notamment pour tenir compte de la distance prédictive d’arrêt. Dans l’exemple ci-dessus, les valeurs seuils du tableau peuvent être multipliées par 100 * D(EPref)(t) lorsqu’il s’agit de comparer la différence ôD(t),
    Selon un mode de réalisation, l’affectation d’un coefficient CoeffAD(t) à la différence AD(t) calculée est conditionnée à une vitesse minimale de l’aéronef et/ou à la présence, pendant une durée prédéfinie, d’une condition de freinage critique de l’aéronef correspondant à un freinage de l’aéronef limité par la friction de la piste ou l'adhérence à la piste.
    Par exemple, la table ci-dessus est utilisée pour déterminer CoeffAD(t) lorsque la vitesse V de l’aéronef est supérieure à une vitesse seuil, 10 nœuds par exemple. Lorsque la vitesse V est inférieure à cette vitesse seuil (l’aéronef est en fin d’atterrissage ou roule sur les voies de roulage, taxiways), le coefficient CoeffAD(t) est directement mis à 0. On évite ainsi des traitements inutiles.
    De même, il peut être considéré que la détermination de si l’état de piste local est plus dégradé que l’état de piste de référence ou non n’a d’intérêt que si l’aéronef est en condition de freinage critique, c’est-à-dire en limite d’adhérence compte tenu de l’état de piste local. Cela a déjà été évoqué plus haut en lien avec l’étape S349.
    Aussi, un registre de freinage critique peut être prévu (initialisé à 0 au début de la Figure 3), lequel registre est incrémenté à cette étape S352 si l’aéronef est en freinage critique à l’instant courant ‘t’. Compte tenu du bouclage par les étapes S354 et S355, la valeur du registre peut croître progressivement et dépasser une valeur seuil prédéfinie, par exemple 8.
    Chaque fois que l’aéronef n’est pas en freinage critique à l’instant courant ‘t’, le registre peut être réinitialisé à 0. Ainsi le registre est représentatif d’une situation de freinage critique qui perdure.
    Comme évoqué ci-dessus, l’affectation d’un coefficient CoeffAD(t) à la différence AD(t) calculée peut alors être conditionnée à la valeur de ce registre, et n’utiliser la table ci-dessus que lorsque le registre dépasse la valeur seuil prédéfinie. Autrement, le coefficient CoeffAD(t) est directement mis à 0, évitant des traitements inutiles.
    Suite à l’étape S352, l’étape S353 prévoit d’évaluer un niveau moyen de dégradation de l’état de piste sur la fenêtre d’analyse [t-T ; T],
    Pour ce faire, l’étape S353 calcule la somme des coefficients CoeffAD(t) déterminés pour chacun des instants de cette fenêtre d’analyse, depuis une dernière réinitialisation.
    Compte tenu de la table ci-dessus, ce calcul comprend l’incrément d’un compteur X lorsqu’une desdites comparaisons S351 indique une différence entre la distance d’arrêt locale estimée et la distance d’arrêt de référence obtenue supérieure à une valeur seuil prédéterminée (environ 3 dans la table) _ en d’autres termes lorsque la décélération mesurée est moins bonne que celle attendue _, et le décrément du compteur lorsque la comparaison indique que la différence est inférieure à la valeur seuil prédéterminée _ en d’autres termes lorsque la décélération mesurée est meilleure que celle attendue.
    Une mise en oeuvre simple de l’étape S353 consiste à ajouter CoeffAD(t) à la valeur courante du compteur X, et à lui retrancher CoeffAD(t-T-s), avec ε le pas entre deux mesures, si aucune initialisation de X n’a eu lieu depuis (en d’autres termes si X incluait bien CoeffAD(t-T-s)).
    Puis à l’étape S354, il est déterminé si le compteur X, représentatif du niveau moyen de dégradation de l’état de piste sur la fenêtre d’analyse, indique une dégradation substantielle de l’état de piste en comparaison à EPref.
    Pour ce faire, X est comparé à une valeur seuil, par exemple à 40 compte tenu des coefficients de la table ci-dessus.
    Il est à noter que la valeur seuil peut être atteinte avant même que l’intégralité de la fenêtre d’analyse soit prise en compte (par exemple 40 mesures peuvent suffire en cas de forte dégradation, c’est-à-dire AD > 25).
    Tant que le seuil n’a pas été atteint, l’instant suivant est considéré en bouclant sur l’étape S355. Dès que le seuil est atteint, signifiant que l’état de piste local est nettement dégradé par rapport à l’état de piste de référence, il est procédé à la mise à jour de l’état de piste de référence à l’étape S360 déjà décrite.
    En outre, lors de cette étape, le compteur X est réinitialisé à 0, afin de commencer une nouvelle fenêtre d’analyse.
    La Figure 5 est une illustration graphique de l’évolution de la distance d’arrêt et du niveau de freinage dans d’un scénario opérationnel d’atterrissage utilisant l’invention. Ce scénario peut notamment mettre en œuvre le mode de réalisation des Figures 3 et 4 où le procédé d’aide au pilotage s’appuie sur une pluralité de comparaison entre des distances d’arrêt prédictives et estimées de mesures courantes.
    Dans ce scénario, un aéronef équipé d’un système d’aide au pilotage selon l’invention, comme par exemple celui décrit en référence à la Figure 1, est en approche d’une piste théoriquement recouverte de neige (EPref = COMPACTED SNOW).
    Le système d’assistance au freinage 10 prend en compte cet état de piste EP et calcule une consigne de freinage ou alerte C(EPref = COMPACTED SNOW) mise en œuvre par un dispositif de freinage ou de restitution une fois au sol au cours d’une phase 1. Cette consigne de freinage ou alerte s’appuie sur une distance d’arrêt D(EPref = COMPACTED SNOW).
    Au cours de la phase 0, l’état de piste local s’avère être de la neige compacte, l’aéronef arrivant à freiner à la consigne demandée (F=F’ - voir (c)). L’aéronef n’étant pas en condition de freinage critique (voir (b)), les coefficients CoeffAD(t) valent tous zéro (voir (d)). Le compteur X reste donc nul, et aucun changement d’état de piste n’est opéré (test S354 négatif).
    Au cours de la phase 1, l’aéronef ayant avancé sur la piste, l’état de piste local apparaît plus dégradé que l’état de piste de référence EPref. En effet, l’aéronef ne freine pas assez (F’) par rapport à la consigne (F) : l’aéronef est en condition critique de freinage. Les distances D|0C(t) estimées sont donc supérieurs aux distances D(EPref)(t) prédites. Pendant cette phase, et après que la condition de freinage critique ait durée quelques instants (par exemple 8 instants), chaque CoeffAD(t) vaut une valeur positive dans l’exemple de la table ci-dessus, incrémentant progressivement le compteur χ. Lorsque celui-ci atteint la valeur seuil (test S354 positif à la fin de la phase 1), l’état de piste est mis à jour à l’état de piste suivant EPmaj=SNOW (voir (a)). L’aéronef débute la phase 2 sans freinage critique (CoeffAD=0). Puis rapidement la piste se dégrade à nouveau, l’aéronef se mettant en freinage critique (voir (b)) ce qui a pour effet, après quelques instants (8 par exemple), d’additionner des CoeffAD(t) positifs (voir (d)). La dégradation de la piste étant progressive (voir la courbe F’ progressive), les coefficients croissent progressivement par paliers (on a représenté seulement trois paliers sur la figure, alors que dans l’exemple de la table ci-dessus, jusqu’à six paliers peuvent apparaître selon la progressivité de la courbe F’ et selon l’amplitude finale de AD). Les coefficients CoeffAD(t) prennent une forte valeur car la dégradation de la piste est importante (EP|0C=ICY par exemple).
    Le compteur X augmente donc progressivement, et lorsque celui-ci atteint la valeur seuil (test S354 positif à la fin de la phase 2), l’état de piste est mis à jour à l’état de piste suivant EPmaj=WrS (voir (a)).
    Ce nouvel état de piste n’est pas représentatif de l’état de piste local. C’est pourquoi l’aéronef ne quitte par l’état de freinage critique en début de phase 3 (voir (b)). Le freinage étant toujours insuffisant (D|0C(t) > D(EPref)(t)), les coefficients CoeffAD(t) prennent une valeur positive inférieure par rapport à la phase 2.
    Le compteur X augmente donc progressivement, et lorsque celui-ci atteint la valeur seuil (test S354 positif à la fin de la phase 3), l’état de piste est mis à jour à l’état de piste suivant EPmaj=ICY (voir (a)).
    Lors de la phase 4, l’aéronef reste en condition de freinage critique mais suffisant (F=F’ et donc D|0C(t) est sensiblement égal à D(EPref)(t)). Les coefficients CoeffAD(t) prennent une valeur légèrement négative dans l’exemple du tableau ci-dessus. Le compteur X n’atteignant pas la valeur seuil, aucun changement ne se produit.
    La phase 5 illustre alors le cas d’une amélioration des conditions de la piste. L’aéronef sort de la condition de freinage critique (voir (b) car F’ > F) et les coefficients CoeffAD(t) sont alors tous nuis.
    Les exemples qui précèdent ne sont que des modes de réalisation de l’invention qui ne s’y limite pas.
    FIELD OF THE INVENTION
    The present invention relates to a method and a system for assisting the piloting of an aircraft, and to an aircraft equipped with such a system.
    BACKGROUND ART OF THE INVENTION
    During the landing and takeoff phases, and more generally the taxiing of an aircraft, knowledge of the surface state of the runway is of paramount importance.
    This surface state or "runway state" has been normalized according to a track state scale offering a plurality of discrete values: generally, dry runway (DRY), wet / wet runway (WET), wet runway (WATER), track with hard snow (CSNW, for "compacted! snow"), snowy track (SNW), frozen track (ICE), ...).
    Indeed, this knowledge depends on the braking performance prediction of the aircraft. It is thus possible: - to estimate as best as possible the distance necessary to stop the aircraft during its landing in the interests of safety, - not to overestimate this stopping distance necessary to immobilize the aircraft and therefore not to penalize, beyond measure, the use of the runway and the aircraft.
    Many flight control systems require the knowledge of this runway state precisely.
    For example, the documents FR2817979 and FR2857468 provide piloting assistance devices during the approach and landing phases, known as Brake-To-Vacate (BTV), for monitoring and controlling the braking of the aircraft through closed-loop control laws. These control laws depend directly on the estimation of stopping distances from the track condition. On the other hand, the documents FR2936077 and FR2914097 provide piloting assistance devices during the approach and landing phases, known as Runway Overrun Protection (ROP) or Runway Overrun Warning (ROW), allowing to detect a risk of runway departure depending on the runway condition, in order to alert the pilot either to induce him to turn on the throttle or to trigger maximum braking.
    However, the braking performance of an aircraft on a so-called contaminated track and therefore the necessary stopping distance are difficult to predict because of the difficulty in knowing reliably and accurately the track condition, determining in the deceleration of the aircraft.
    Traditionally, runway conditions are determined by ground personnel, or evaluated by a pilot on landing and reported in a landing report. This runway status information, transmitted to the approaching aircraft, is however unreliable and possibly out of date rather quickly. Indeed, the track condition characteristics are of high volatility over time.
    In order to make reliable the estimation of a runway condition, the documents FR2930669 and FR2978736 propose solutions making it possible to automatically estimate the state of the runway from the measured braking performance of an aircraft during its landing, and this regardless of the type of aircraft.
    However, the track condition thus determined and provided to the aircraft on approach does not make it possible to account for a possible degradation of the runway occurring between the two landings.
    In order to take account of this possible runway degradation, the document FR3007179 provides for determining a local information function of a local runway condition characterizing a runway area on which the aircraft rolls during landing. This local information, when it informs of a local track condition more degraded than a reference track state, is used to update in real time or near real-time the track condition or braking data that resulting.
    The updated braking data can then be provided at the input of a brake assist module, which generates in response a braking instruction to control a braking device of the aircraft,
    The process of updating the track condition is called "unidirectional" because only a degradation of it is allowed, without the possibility to improve it during the landing. This limitation was put in place for security reasons. Indeed, the temporary improvement of the deceleration capabilities of the aircraft should not be credited by improving the qualification of the runway condition, since there is no guarantee that this improvement will last until the end of the flight. stopping the aircraft.
    FIG. 1, taken from document FR3007179, illustrates a system for assisting the piloting of an aircraft during the landing phase according to this same document. In this system, the determination of whether the local track state is more degraded than the reference track state is led by a comparison between two data of the same nature iref and i | 0C. This reference and local information are either track conditions or current braking or deceleration levels of the aircraft.
    This system based on the braking or deceleration levels, however, has the disadvantage that it applies the same criteria triggering the update of the track condition or braking data, throughout the landing and taxiing on the track.
    The present invention aims to improve the piloting assistance of an aircraft especially during the landing phase.
    SUMMARY OF THE INVENTION
    Indeed, the inventors have noted that the same deceleration difference (between that measured and a desired setpoint calculated from the reference track state) produces substantially different effects on the braking input data of the module. braking assistance, depending on whether the aircraft is at the beginning of the runway landing (high taxi speed) or at the end of the landing (low taxi speed).
    This is because a given high speed deceleration reduces the braking distance significantly, while the same low speed deceleration reduces the braking distance marginally.
    The choice of the threshold of deceleration deviation to trigger the update is then extremely delicate. On the one hand, it is not desirable to trigger the update too easily due to the non-reversible process. Indeed, degrade the track condition can cause inconvenience to passengers and increase the wear of the aircraft, due to stronger decelerations imposed by the braking system in response to this update. For example, it is not useful to use thrust reversers when the track condition does not warrant it. Similarly, if the track condition is degraded at the ICE level, the braking system will command a maximum braking pressure which, on a track whose track condition is in fact DRY, will result in a very high level of braking. deceleration and a significant increase in the temperature of the brakes may eventually lead to automatic deflation of the tires to prevent their explosion. On the other hand, it is undesirable to trigger this update unnecessarily because of the discontinuous effects (because the scale of track states is discontinuous) that it may have. In particular, the passage into a lower level of track can instantly trigger a battery of sound alerts in the cockpit, degrading the quality of communication with the control tower, or stressing the crew. It can also substantially impact the occupation time of the track, because a very strong braking due to a degradation of the level of track condition generally leads, if it is inappropriate, to an extended driving time. Indeed, after a strong deceleration resulting from the strong braking, it is often necessary to reset the throttle, while the aircraft has a slow speed, to reach an exit ramp.
    It therefore seems useful to improve the decision-making process of degradation of the track conditions.
    The inventors have thus sought to base it on more relevant parameters. For this purpose, the invention aims in particular at a method of assisting the piloting of an aircraft during the landing phase, comprising the following steps performed by the aircraft: generating a reference braking data as a function of a state of reference track; determining local information based on a local runway condition characterizing a runway area on which the aircraft rolls upon landing; when the local information informs a local track condition more degraded than the reference track state, update the reference track state and generate an updated braking data according to the state of track updated; and supplying the reference braking data and, if need be, updating the input of a brake assist module capable of generating a braking setpoint for controlling a braking device of the aircraft, the method being characterized in the local information includes a local stopping distance estimated from local measurements made in the aircraft, and further comprising the steps of: obtaining a reference stopping distance from the Reference braking data, and comparing the local stopping distance with the reference stopping distance to determine whether the local track condition is more degraded than the reference track condition or not.
    Thus, the decision to update the runway status is no longer based solely on a detected difference between a set deceleration (taking into account the reference runway condition) and a current deceleration (measured locally) of the runway. aircraft, which had disadvantages as discussed above. Now, the process of irreversibly updating the track condition is more relevant and more robust.
    This is achieved by comparing stopping distances rather than deceleration values. Indeed, by passing at stopping distances, the invention integrates directly in its decision-making process the actual impacts that the detected deceleration deviation induced, given the variable (decreasing) speed of the aircraft on the runway. during landing. In other words, it is now possible to accept greater deceleration deviations at the end of the roll than at the beginning of the roll, because their impact on the braking distance is substantially different.
    The braking performance and therefore the safety of the aircraft during landing are therefore improved.
    Correlatively, the invention also provides a system for assisting the piloting of an aircraft during the landing phase, the system being embedded in the aircraft and comprising: a module for generating a reference braking data as a function of a reference track condition; a module for determining a local information function of a local runway condition characterizing a runway area on which the aircraft rolls during landing; a module for updating the reference track state when the local information informs of a local track state more degraded than the reference track state, said generation module then being configured to generate a datum of braking updated according to the updated track condition; and a brake assist module receiving as input the reference braking data, then that updated if necessary, configured to generate a braking setpoint for controlling a braking device of the aircraft, the system being characterized in that the local information includes a local stopping distance estimated from local measurements made in the aircraft, and further comprising: a module for obtaining a reference stopping distance from the data reference brake, and a comparator for comparing the local stopping distance with the reference stopping distance to determine whether the local track condition is more degraded than the reference track condition or not.
    The piloting aid system has advantages similar to the method according to the invention. Other features of the method and the piloting aid system according to different embodiments are described in the dependent claims.
    In embodiments, said comparison comprises comparing the difference between the local stopping distance and the stopping reference distance with a predetermined threshold value. Note that this difference can be the simple difference between the two mentioned distances, or alternatively a relative difference retranscribing for example the percentage of variation of the stopping distance, between that of reference and that local.
    In particular embodiments, the predetermined threshold value is a function of a distance between the aircraft and an end of the runway on which the aircraft rolls during landing. This arrangement makes it possible to dynamically adjust the updating process according to the risks of leaving the track. Of course, a margin of safety can be taken into account.
    In other particular embodiments, the predetermined threshold value is a function of the reference track state. This approach makes it possible to adjust the accepted tolerance to braking uncertainties related to the different climatic conditions that correspond to the different possible track conditions.
    In other particular embodiments possibly combinable, the predetermined threshold value is a function of the reference stopping distance. This makes it possible to compare the simple difference between the two mentioned distances, while ensuring a relative consideration of this difference.
    In embodiments, the determination of whether the local track state is more degraded than the reference track state or not is a function of a plurality of estimated local stopping distances for a respective plurality of time instants. consecutive.
    It can thus be set up a filtering on a time window of analysis. In particular, the latter can be defined so that said plurality of consecutive instants covers several seconds, for example 10 seconds leading for example to 80 measurements (for 8 measurements per second).
    Each local stopping distance at a current instant can in particular be estimated from local measurements made in the aircraft for the current time instant 't', in particular measurements made between 't-1' and 't'. for example a measurement of position and speed of the aircraft (GPS) as well as an instantaneous deceleration measurement.
    This prevents very transient measurements over time (for example a puddle traversed by the aircraft) can not affect in a non-reversible way the track condition taken into account for braking.
    In particular embodiments, the determination comprises a plurality of comparisons respectively between each estimated local stop distance and a corresponding reference stop distance estimated from the reference braking data for the same time instant. Indeed, it is appropriate each time (that is to say at each instant 't') to calculate the stopping distance theoretically remaining given the state of the reference track. Thus, the comparison between the distances is raised to be precise.
    In other particular embodiments, the determination comprises incrementing a counter when one of said comparisons indicates a difference between the estimated local stopping distance and the resulting stopping distance greater than a predetermined threshold value. in other words, when the measured deceleration is not as good as expected, and the decrement of the counter when the comparison indicates that the difference is less than the predetermined threshold value, in other words when the measured deceleration is better than the expected one.
    There is thus a counter filtering the stopping distance differences during an analysis window.
    According to a particular characteristic, the increment or decrement value is a function of said difference, and in particular of the relative difference mentioned above. For example, the increment may be X when the stopping distance increase is 10% of the reference stopping distance (in other words, a relative difference of 10%) and is Y <X when increasing the stopping distance is 5% of the reference stopping distance.
    This results in intelligent filtering which on one side can bring out the large differences in stopping distances, and on the other hand, can neglect the relatively small ones.
    According to another particular characteristic, the predetermined threshold value and / or the increment or decrement value is a function of the reference track state. Again, this configuration makes it possible to take into account the braking uncertainties related to the various climatic conditions (which correspond to the different possible track conditions) when it comes to assessing the impact of a difference between stopping distances. .
    According to another particular characteristic, the increment or the decrement of the counter is conditioned at a minimum speed of the aircraft and / or at the presence, for a predefined duration, of a critical braking condition of the aircraft corresponding to a Aircraft braking limited by runway friction or track adhesion. This arrangement avoids unnecessary calculations.
    In the first case, it is in particular because, during the low speed taxiing phases, for example at 10 knots, in particular when the aircraft finishes decelerating on the runway or when it is traveling on the taxiways. taxiways, the risks of leaving the track for failure to brake are discarded. An adjustment of the reference track condition is therefore no longer necessary.
    In the second case, it is notably because all the braking capacities are not exploited by the aircraft. Also, even if the reference runway condition does not correspond to the actual state of the runway, it does not prevent an effective landing according to the instructions (reference braking data) supplied to the assistance module. braking.
    In particular, it can be provided that the critical braking condition is at least one of: the difference between a commanded deceleration value of the aircraft and a deceleration value measured by the aircraft exceeds a predetermined threshold; the level of manual depression of a brake pedal by an operator exceeds a predetermined threshold; the difference between a controlled braking level of the aircraft and a measured braking level in the aircraft exceeds a predetermined threshold; an anti-skid system of the aircraft is triggered.
    According to another particular characteristic, the reference track state is updated when said counter exceeds a threshold value. As a result, the update only takes place if a degraded track state is detected (via a longer estimated stopping distance) a sufficient number of times in the analysis window. Therefore, this provision provides filtering of the analysis to suppress very localized events.
    In a particular embodiment, the update of the reference track state includes the degradation of the reference track condition of only one of a range of track states. In other words, the track state is not necessarily updated directly with a local track condition that could be derived from local measurements during the analysis window. We limit ourselves here to degrade the state of reference of a single level, before starting again on a new window of analysis.
    This configuration also participates in progressive filtering. Indeed, if only a portion of the runway is significantly more degraded than the rest of the runway, the degradation of the runway condition resulting from an analysis of this portion remains limited, and an analysis on the following portions of the runway does not lead to increased degradation.
    According to embodiments of the invention, the method further comprises the steps of: obtaining an updated stopping distance from the updated braking data; comparing the updated stopping distance to a distance from the aircraft with an end of the runway; and take an action when the updated stopping distance is greater than the distance of the aircraft with the end of the runway, possibly taking into account a margin of safety.
    This configuration aims to ensure safety during landing. By way of examples, said action taken may comprise at least one of the following actions: controlling a higher deceleration of the aircraft, and alerting a crew of the aircraft that a braking distance is too long.
    According to other embodiments of the invention, the method further comprises an updated track status reporting step to a crew of the aircraft. The pilot can adapt his actions and in particular his speed to choose a runway evacuation and to roll on it.
    All or part of the methods according to the invention can be implemented by computer, combining software and hardware. The invention can thus be stored in the form of a computer program product comprising instructions adapted to the implementation of each of the steps of the method when said program is executed by a microprocessor. The invention also relates to an aircraft comprising at least one flight control system as defined above. It is thus adapted to implement the above-mentioned piloting assistance method.
    BRIEF DESCRIPTION OF THE FIGURES Other features and advantages of the invention will become apparent in the following description, illustrated by the accompanying drawings, in which: FIG. 1 illustrates a system for aiding the piloting of an aircraft according to the state of the art; FIG. 2 illustrates a system for aiding the piloting of an aircraft, in accordance with particular embodiments of the invention; FIG. 3 represents, in the form of a logic diagram, the main steps of a method of assisting the piloting of an aircraft according to embodiments of the invention; FIG. 4 represents, in the form of a logic diagram, steps of one embodiment of a step of determining a track state degradation implemented during the method of FIG. 3, according to embodiments of FIG. of the invention; - Figure 5 illustrates an operational scenario of a landing during which the invention is used.
    DETAILED DESCRIPTION OF THE INVENTION
    FIG. 2 diagrammatically represents a system 1 for aiding the piloting of an aircraft, in accordance with particular embodiments of the invention. This figure is based on Figure 1 of the state of the art.
    The system 1 comprises a braking assistance system 10 which, from a reference track state EPref, for example received from a previously landed aircraft or from a ground station, generates a setpoint C (EPref ) of braking provided at the input of a braking device of the aircraft or generates a warning message C (EPref) provided at the input of a device for restitution of the aircraft. Note that the alert message may be a non-alert message at the beginning of the landing.
    The braking assistance system 10 comprises a module 11 for generating a braking data as a function of the reference track state EPref and comprises a braking assistance module 12 configured to generate the braking setpoint C ( EPref) from the braking data generated. The brake assist module 12 thus calculates in real time braking instructions adapted to the actual landing conditions. These instructions make it possible, for example, to target the end of the runway (or a little before depending on a safety margin) in order to protect the aircraft, or to target a previously selected point of interest for the current mission ( for example an off-ramp to a taxiway or taxiway minimizing the time of occupation of the track or minimizing the path to the boarding gate).
    In the example of the figure, the braking data generation module 11 is a stop distance estimator configured to estimate a predictive stopping distance D (EPref) of the aircraft as a function of the state. reference track EP, and possibly other parameters of the aircraft such as its characteristics (mass, configuration of spouts / flaps, ...), its performance (ability to decelerate in a given configuration, braking capacity,. ..) or its characteristics of control (speed of the aircraft), position with respect to the threshold of track, ...), and local parameters (direction and direction of the wind, ...). The EPref runway condition is generally based on models provided by regulations, for example the following status scale in increasing order of degradation: DRY (for dry runway), WET (for wet runway), COMPACTED SNOW (CSNW , for packed snow), SNOW (SNW for runway snow), WATER or SLUSH (WTS, for runways contaminated by standing water or slush), and ICY (for ice).
    The brake assist system 10 may for example be a Brake-To-Vacate (BTV) type device as described in documents FR2817979 and FR2857468 allowing the pilot to control the braking of the aircraft as a function of a distance. theoretical stop associated with the reference track state EPref. The braking setpoint C (EPref) generated by the device BTV thus controls a braking device, for example brakes, air brakes, etc.
    This braking setpoint C (EPref) may for example represent a braking command imposing a certain deceleration corresponding to the predictive stopping distance D (EPref) for the aircraft.
    Alternatively, the brake assist system 10 may be a warning device and runway risk management type Runway Overrun Protection (ROP) as described for example in documents FR2936077 and FR2914097.
    The ROP adjusts the predictive stopping distance at the output of the stopping distance estimator according to the input reference track state, and therefore, if certain conditions are met (for example, if the predictive distance stop brings the aircraft close to the end of the runway or outside thereof), can issue alerts and / or braking orders.
    These alerts may consist of visual or sound messages displayed or broadcast in the cockpit of the aircraft, for the attention of the crew. A braking command may be an automatic maximum brake command (full pressure) to the braking device.
    The system 1 also comprises a module 20 for determining a local information function of a local runway condition for the aircraft characterizing a runway zone on which the aircraft rolls during landing. This determination is for example made from so-called local measurements in the sense that at least one physical quantity of the aircraft is measured during the landing at the moment when the aircraft is rolling in the part of the runway considered as "local".
    For this, the aircraft is equipped with sensors ad hoc for example located at each wheel to determine for example the vertical load applied to them and / or the braking torque applied by the braking system, or the speed of wheel rotation during landing. The aircraft can also include one or more ADI RS (in "Air Data Inertial Reference System") inertial units for obtaining measurements of aircraft ground speed, position, acceleration and temperature, a system flight management system (FMS), an equipment for estimating the physical size of the tires (temperature and internal pressure), and a GPS module providing the position of the aircraft.
    Another physical quantity that can be measured is the level of depression of the brake pedals by the pilot or a brake pressure.
    In general, many data can be provided and used to determine local information. By way of illustration, the module 20 receives the location of the center of gravity CG of the aircraft, the slope of the runway, the outside temperature, wind data (force and direction), speeds (on the ground, true and calibrated aerodynamics). wheels), altitude data (pressure, ...), aircraft mass, airport data, track data used including GPS coordinates of the runway, GPS position data of the aircraft, engine operating parameters, brake pedal depressing information, mobile surface conditions (such as high lift devices, elevator, airbrakes, ailerons), relative measurement information to the tires (internal temperature and pressure), representative Boolean information, for example the feel of the main landing gear on the runway and the opening of the engine thrust doors, etc.
    It should be noted that all or part of these data, mainly those relating to dynamic data of the aircraft or external conditions for example, can be updated as a function of time, in particular during the running of the aircraft: speeds, engine thrust levels , wind, temperature and tire pressure, etc. The measured data can then be timestamped to facilitate the reconciliation of certain measurements with the ground speed of the aircraft at the same time and / or the runway area (position of the aircraft) on which the aircraft is traveling at the same time. .
    These measurements made by the different sensors are transmitted to the determination module 20 which then calculates said local information as a function of these.
    According to embodiments of the invention, the local information consists of a local stopping distance D | 0C, that is current in view of the area where the aircraft rolls, estimated from the measurements. performed in the aircraft.
    This local stopping distance can be performed repeatedly, for example every 125 ms so as to have 8 measurements per second. Note D | 0C (t) the local stopping distance estimated at time 't'. By way of illustration, the methods and systems of the applications FR2930669 and FR2978736 can be used for the implementation of the determination module 20. These methods and systems evaluate, in particular, the braking or deceleration performance of the aircraft to estimate a runway condition. current.
    For example, the balance of forces makes it possible to obtain the braking force Fb of the aircraft by the following formula: ma = T - Daero - Fb - Dcont - mgsin γ, where m is the mass of the aircraft, acceleration (or deceleration), T engine thrust (for example obtained by the position of the throttle lever and engine parameters such as the engine speed), Daero aerodynamic drag (for example obtained by modeling from various parameters, for example the angle of incidence, the longitudinal attitude, an output of the airbrakes), Doom the drag resulting from a track contaminant (for example based on a track profile corresponding to the track state EP) and γ the slope of the track.
    A local stopping distance D | 0C (t) can be estimated, for the moment 't', from this calculated braking force Fb (t) for the moment 't',
    The system 1 further comprises a comparator 30 and a feedback loop of this comparator to the brake assist module 10 and / or a register storing the reference track state EPref for the purposes of implementing the invention. .
    The comparator 30 makes it possible to compare the local stopping distance D | 0C with the reference stopping distance D (EPref) to determine whether the local track state, denoted EP | 0C, is more degraded than the state of EPret reference track or not. Note that the two input data of the comparator 30 are of the same nature.
    In the example of the figure, the reference stopping distance D (EPref) is in particular provided directly from the output of the stop distance estimator 11. More generally, this reference stopping distance D (EPref) can be obtained from any braking data generated by the module 11 from the reference track state EPref.
    According to the invention, the comparison by the comparator 30 is therefore intended to determine a possible degradation of the local runway state with respect to the reference runway condition, based on the estimated stopping distances, rather only on deceleration differences. The detection of a change of track condition is then more relevant and more robust. This is particularly because this approach takes into account the speed of the aircraft, while that based on simple differences in deceleration does not capture the real impact of these differences on the braking process of the aircraft. .
    The comparison may in particular simply compare the difference between the local stopping distance and the reference stopping distance to a predetermined threshold value. The latter is preferably a function of a distance between the aircraft and an end of the runway on which the aircraft rolls during landing in order to detect a situation where the increase of the stopping distance due to a degradation of the runway condition leads to a risk of runway excursion. The threshold value can also be a function of the reference track state. This makes it possible to appreciate this risk of leaving the track with regard to the braking uncertainties that may result from poor track conditions.
    In one embodiment, the predetermined threshold value is a function of the reference stopping distance. This embodiment thus makes it possible to evaluate a difference in relative distance.
    Although the comparison to determine if the local track state EP | 0C is more degraded than the reference track state EPref or not can be based on a single estimate of a local stop distance D | 0C, preferred embodiments of the invention provide that the comparison is a function of a plurality of local stop distances D | 0C (t) estimated for a respective plurality of consecutive time instants, for example 80 measurements corresponding to 10 s of 'analysis. Correspondingly, a plurality of reference stopping distances D (EPref) (t) are considered, each corresponding to an estimate of the predictive stopping distance of the aircraft given its configuration at the instant 't . To do this, the module 11 can produce, from the reference track state EPref, a braking data which takes the form of a function representative of the predictive stopping distance D (EPref) in time. For example, D (EPref) = - V2 / (2 * JX) where V is the speed of the aircraft and JX is the longitudinal acceleration (therefore negative for a deceleration) estimated at the limit of adhesion given EPref. Also, D (EPref) (t) = - V (t) 2 / (2 * JX (t)), where JX can possibly be constant in time.
    This approach can be likened to filtering or averaging estimates over a time window of analysis to increase the robustness of the process of updating runway conditions. Indeed, taking into account a more or less large number of estimates of D | 0C (t) according to a filtering makes it possible to attenuate the transient effects of a very punctual and isolated degradation (for example a puddle or plate of ice). Without this filtering, a single estimate made at the level of this one-off degradation but not representative of the track in its entirety would lead to feeding the brake assist system 10 with a non-representative modified track condition. Possible consequences are an inconvenience for the passengers if the aircraft has to put back the throttle, and an increased stress (and thus wear) of components (for example brakes, engines) of the aircraft.
    When the result of the comparison shows that the track condition has not deteriorated since the previous landing (the reference runway condition), the brake assist system 10 has data (runway condition). reference EPref and predictive stopping distance D (EPref)) which guarantee efficient braking. Thus, none of these data of the system 10 is updated, so that the braking setpoint or the alert C (EPref) initially generated by the braking assistance system 10 from the track condition reference is maintained.
    On the contrary, when the result of the comparison shows that the track condition has deteriorated (that is, when the local information indicates a local track condition more degraded than the track condition of reference), the data of the brake assist system 10 are de facto out of date and no longer guarantee braking safety of the aircraft. The invention then provides that the reference track state EPref is updated, in order to adapt in real time the braking of the landing to the actual runway conditions. Indeed, the updated track state EPmaj now represents a new reference track state (thanks to the feedback loop shown in the figure, the old reference track state can be overwritten in memory) from which it is possible to generate an updated brake data update D (EPmaj) again and to supply it to the input of the brake assist module 12, in order to also update the brake setpoint or the warning C (EPmaj).
    Preferably, the update of the EPret reference runway state comprises the degradation of the reference runway state of only one of a runway state scale, and not a degradation to the runway state. local EP | 0C if it is too degraded compared to the reference track state EPref. In other words, the update process only degrades the track state by one step in the state scale considered.
    An alternative to overwriting the EPref value in memory may be to directly supply the brake assist system 10 with the value EPmaj, the system taking account of EPref when no modified state EP | 0C is supplied, and taking into account account of EP | 0C when the latter is provided.
    Thus, the flight control system according to the invention comprises: a module 11 for generating a braking data D (EPref) as a function of a reference track state (EPret); a module 20 for determining a local information function of a local runway condition (EP | 0C) to the aircraft during landing, that is to say a local runway condition characterizing a runway area on which the aircraft rolls during landing, the local information including a local stopping distance D | 0C estimated from local measurements made in the aircraft. Preferably, several estimates D | 0C (t) are made at several times 't'consecutive; an update module (10,30) of the reference track state EPref according to the local information determined when the local information informs a local track state EP | 0C more degraded than the state reference track EPref, said generation module then being configured to generate an updated braking data D (EPmaj) as a function of the updated track state; and a brake assist module 12 receiving as input the reference braking data D (EPref) and then updated D (EPmaj), if necessary, configured to generate a braking setpoint C (EP) for controlling a device braking of the aircraft.
    Such a piloting aid system can be integrated in a single computer, or, alternatively, its various functions can be divided between several computers communicating with each other for example to reuse existing computers.
    The new track condition obtained is then used to adjust the braking of the aircraft. Alerts can also be escalated if necessary.
    In one embodiment, the new runway condition or any information indicating a degradation of the runway condition is notified to the crew of the aircraft. He can then knowingly adapt his actions, including adapting his speed for the runway evacuation phase.
    An automated decision-making process can also be implemented. Thus, in embodiments, once the track condition has been updated, an updated stopping distance is obtained from the updated braking data (from module 11 from the state updated track), then this updated stopping distance is compared to a distance from the aircraft with an end of the runway to determine if there is a risk of runway excursion. The position of the aircraft can in particular be obtained either directly by GPS, or in a hybrid manner using several dissimilar information so as to reduce the probability of errors, for example GPS combined with the integration of a speed vector. obtained at the level of wheel rotation sensors and / or the dual integration of an acceleration vector obtained using an inertial unit.
    Finally, an action is taken when the updated stopping distance is greater than the distance of the aircraft with the end of the runway, possibly taking into account a margin of safety. By way of example, such an action can be one or the following two actions: control a higher deceleration of the aircraft, for example by acting on the hydraulic pressure of the brakes or on the thrust reversers, ...; and alerting a crew of the aircraft that a braking distance is too long, for example by visual or audible indication. In this case, the crew has a set of deceleration means to adjust the landing, or can reset the throttle in case of risk of leaving the track.
    FIG. 3 represents in the form of a logic diagram the main steps of a piloting assistance method according to a particular embodiment of the invention. This method can be implemented in a flight control system according to the invention, as for example described with reference to FIG. 2.
    During a step S310, a theoretical or reference track state EPref is received by the aircraft, for example from an aircraft having previously landed or from a ground station.
    For example, this reference track state EPref may be the result of a synthesis of several track conditions obtained during previous landings of several aircraft, this synthesis being carried out by the aforementioned ground station.
    Then, during a step S320, the brake assist system 10 generates a braking setpoint or a warning message C (EPref) as a function of this reference track state EPref. This step comprises the estimation of a braking data, for example of a function representative of the predictive stopping distance D (EPref) in time, by the estimator 11 as mentioned above.
    The braking setpoint C (EPref) may be of different types. This may include applying a certain amount of braking force, a level of depression of the brake pedals, a deceleration level to reach, a stopping distance to reach or a brake pressure. For example, the deceleration level to be achieved can be calculated as an operationally acceptable deceleration level for the aircraft given the reference track condition EP. As a variant, it may be the deceleration level reached by the aircraft in a critical braking condition.
    It is the same for the stopping distance to reach: an operationally acceptable stopping distance or, alternatively, a minimum stopping distance possible for the aircraft in a critical braking condition. Like the aircraft before on the runway, this stopping distance considered decreases over time, according to a function based on the speed and the deceleration of the aircraft.
    The braking conditions are said to be critical when the aircraft reaches a braking level limited by the friction of the track or the adhesion to the track.
    The alert message may be a voice or visual message to the pilot providing brake instructions to apply. In step S325, the predictive stop distance D (EPref) (t) for the current instant is obtained, for example from the function indicated above or from a braking data generated by the Module 11. The first moment considered in the algorithm may be the one where the landing gear touches the runway for the first time, since it is from this moment that local measurements (step S330 below) to determine a local runway condition can be conducted.
    This predictive stopping distance D (EPref) (t) is provided at the input of the comparator 30.
    Local measurements are made during a step S330 in order to determine (step S340) a local information function of the local track condition EP | 0C, in particular a local stop distance D | 0C (t) estimated, for the current moment 't'.
    This local information may for example be derived from a deceleration level F 'current, itself obtained directly from an accelerometer. Furthermore, a local track condition can be obtained by implementing the mechanisms of the aforementioned documents FR2930669 and FR2978736, from which the distance D | 0C (t) can be estimated.
    The method continues in step S350 where a test consists of comparing the local information D | 0C (t) estimated during step S340 with the reference information D (EPref) (t) of the same nature obtained. at step S325. The comparison can simply compare a difference between these two values to a threshold value as explained above.
    When the threshold value depends on the predictive stop distance D (EPref) (t), a relative difference is thus evaluated.
    A more complex filtering mechanism is illustrated below in connection with Figure 4 which shows an embodiment of step S350. The purpose of the S350 test is to determine if a local runway condition is found to be more degraded than the reference runway condition.
    It can be seen that, by comparing D | 0C (t) and D (EPref) (t), the method according to the invention can detect the same degradation of the runway state at the beginning of landing on the runway and at the end of landing on the runway, without relying on a deceleration differential (between the measured one and the setpoint one) identical. Indeed, a greater deceleration differential is accepted at the end of landing before degrading the track condition. Note that the execution of the test S350 may be conditioned to the determination (S349) of whether the aircraft meets a critical braking condition.
    For example, the critical braking or deceleration level F (for example, theoretically attainable deceleration at the limit of adhesion to the track) as obtained in step S325 is representative of a maximum level of braking to be achieved (maximum deceleration, minimum stopping distance ...), that is to say obtained in critical braking condition of the aircraft. In the absence of a critical braking condition, the aircraft has additional braking capabilities that remain intentionally unexploited. This is because the required braking is more than enough to make a safe landing. There is therefore no interest in determining and treating a possible degradation of the track condition. Thus, with the test S349, one can get rid of unnecessary calculations. By way of illustration, the critical braking conditions resulting from braking limited by the friction of the track are encountered when the difference between a commanded deceleration value of the aircraft and a deceleration value measured by the aircraft exceeds a predetermined threshold. ; the level of manual depression of a brake pedal by an operator (eg driver) exceeds a predetermined threshold; the difference between a controlled braking level of the aircraft and a measured braking level in the aircraft exceeds a predetermined threshold; or an anti-skid system of the aircraft is triggered.
    Another example where the condition S349 is implemented is that implementing the mechanisms of the publication FR2930669 referred to above when determining a local track condition when estimating D | 0C (t) at the stage S340, because this determination is made only in the presence of critical braking conditions of the aircraft. Note that the distance D (EPref) (t) being used only in step S350, step S325 can be performed at any time of the process between steps S310 and S350, independently of steps S330 , S340 and S349 in particular. For example, step S325 can be performed subsequent to the verification of condition S349 in order to avoid an unnecessary calculation of the theoretically achievable deceleration.
    When the test S350 shows that the track condition has not degraded, the method continues in step S355 to consider the next instant and then loops back to the above steps to obtain the dynamic data dependent on T, i.e. loopback on step S325 in the example of the figure. Here, the data used by the system 10, in particular the reference track state (and therefore the braking setpoint or the alert C (EPref)) is not updated. The aircraft thus retains the same braking or warning set because the runway is not further degraded.
    When the comparison or comparisons of the S350 test show that the track condition has degraded relative to the reference track state, the reference track condition ΕΡΓθί is updated during a step S360 so that to take into account the degradation of the runway since the previous landing and thus establish a satisfactory level of braking safety for the landing. The updated runway state EPmaj can take the value of the local track state EP | 0C which results from the measurements made in step S330. However, in a preferred variant, the reference track state EPref is degraded by one level: EPmaj = EPref -1.
    In order to allow the new track state to be taken into account, the latter is stored in the variable EPref used by the module 11: EPrefEPmaj.
    Then the method loops back to step S320 to generate a new braking setpoint or a warning message C (EPref) = C (EPmaj) from the new track state obtained during update S360.
    This loopback allows an update in real time or near real and dynamic of the setpoint or alert during landing.
    Figure 4 illustrates, using a logic diagram, steps of an embodiment of step S350 of Figure 3 according to particular embodiments of the invention.
    This embodiment is similar to a filtering of the measurements over time, in particular because the determination of whether the local track state is more degraded than the reference track state or not is a function of a plurality of distances. estimated local stop for a respective plurality of consecutive time instants.
    Thanks to the looping resulting from the test S354 described hereinafter and going through step S355 to consider a next instant of measurement, the embodiment of FIG. 4 makes it possible to integrate several past measurements made at times between 'tT'. and the current moment 't' (for example T = 10s making it possible to take into account up to 80 measurements) and to take a decision at time t.
    As will be described later, a decision to degrade the track condition can be taken by summation of indicators or quantitative coefficients (positive or negative) determined for each of the instants considered and comparison with a threshold value.
    Such averaging or filtering makes it possible to ignore transient fluctuations of local measurements of track condition.
    In details of an embodiment, the step S350 receives as input the two distances D | 0C (t) and D (EPref) (t) for the current moment 't'. In step S351, two distances are compared, for example by calculating a difference AD (t). By way of example, D (EPref) (t) = - V (t) 2 / (2 * JX) as mentioned above, and Dioc (t) = - V (t) 2 / (2 * 9.81 * AX (t)) where AX (t) is the longitudinal acceleration of the aircraft measured at the current time 't'.
    In one embodiment, the difference 5D between the two distances is first calculated: 5D (t) = D | 0C (t) - D (EPref) (t).
    As a variant, a relative difference AD is calculated, for example as a ratio of elongation or reduction of the estimated stopping distance: AD (t) = 100 * δD (t) / D (EPref) (t) = 100 * (D, oc (t) - D (EPref) (t)) / D (EPre,) (t).
    This relative difference makes it possible, for example, simply to express the percentage increase in the stopping distance between that predicted and that determined locally.
    In the following we will mainly refer to the relative difference AD, although the difference 5D can also be used, with slight adjustments in the calculations.
    Taking into account the looping by the steps S354 and S355, the determination of whether the local track condition is more degraded than the reference track state or not comprises a plurality of comparisons respectively between each estimated local stop distance D | 0C (t) and a corresponding reference stopping distance D (EPref) (t) estimated from the reference braking data for the same time instant.
    Following step S351, step S352 consists in determining an indicator or quantitative coefficient, denoted CoeffAD (t), for AD (t).
    The table below illustrates an example of a table of correspondence associating, in a discrete way, a CoeffAD coefficient with a given difference AD. It can be seen that this association consists in comparing AD with one or more threshold values defined in the first column.
    In this implementation, the value of the coefficient is, on the one hand, a function of said relative difference AD, and, on the other hand, a function of the reference track state. Of course, any one of the criteria can be used alone.
    Indeed, on a dry track (EPref = DRY), CoeffAD (t) = 0,1 if AD (t) e [3; 6 [, while CoeffAD (t) = 1 if AD (t) e [16; 25 [.
    Similarly, if AD (t) = 15, Coeff4D (t) = 0.4 when the track is wet (EPref = WET), while CoeffAD (t) = 0.6 in case of dry track. Note that in the alternative to the use of the relative difference AD, the distance δD can be used. In this case, the threshold values of the first column of the table above can be adjusted, in particular to take account of the predictive stopping distance. In the example above, the threshold values of the array can be multiplied by 100 * D (EPref) (t) when comparing the difference δD (t),
    According to one embodiment, the allocation of a coefficient CoeffAD (t) to the calculated difference AD (t) is conditioned by a minimum speed of the aircraft and / or the presence, for a predefined duration, of a critical braking condition of the aircraft corresponding to a braking of the aircraft limited by the friction of the track or the adhesion to the track.
    For example, the table above is used to determine CoeffAD (t) when the speed V of the aircraft is greater than a threshold speed, 10 knots for example. When the speed V is below this threshold speed (the aircraft is at the end of landing or rolls on the taxiways), the coefficient CoeffAD (t) is directly set to 0. This avoids unnecessary treatments.
    Similarly, it can be considered that the determination of whether the local runway condition is more degraded than the reference runway condition or not is only relevant if the aircraft is in a critical braking condition. that is to say in limit of adhesion taking into account the state of local track. This has already been mentioned above in connection with step S349.
    Also, a critical braking register can be provided (initialized at 0 at the beginning of FIG. 3), which register is incremented at this step S352 if the aircraft is in critical braking at the current instant 't'. Given the looping by steps S354 and S355, the value of the register can increase gradually and exceed a predefined threshold value, for example 8.
    Whenever the aircraft is not under critical braking at the current time 't', the register can be reset to 0. Thus, the register is representative of a critical braking situation that persists.
    As mentioned above, the assignment of a coefficient CoeffAD (t) to the calculated difference AD (t) can then be conditioned to the value of this register, and use the table above only when the register exceeds the predefined threshold value. Otherwise, the coefficient CoeffAD (t) is directly set to 0, avoiding unnecessary treatments.
    Following step S352, step S353 provides for evaluating a mean level of degradation of the track condition on the analysis window [tT; T]
    To do this, step S353 calculates the sum of the coefficients CoeffAD (t) determined for each of the instants of this analysis window, since a last reset.
    Given the above table, this calculation includes the increment of a counter X when one of said comparisons S351 indicates a difference between the estimated local stop distance and the reference stopping distance obtained greater than a value. predetermined threshold (about 3 in the table) in other words when the deceleration measured is less than expected, and the decrement of the counter when the comparison indicates that the difference is less than the predetermined threshold value in d. other terms when the measured deceleration is better than expected.
    A simple implementation of step S353 consists in adding CoeffAD (t) to the current value of the counter X, and in subtracting CoeffAD (tTs), with ε the step between two measurements, if no initialization of X has occurred since (in other words if X included CoeffAD (tTs)).
    Then, in step S354, it is determined whether the counter X, representative of the average level of degradation of the track condition on the analysis window, indicates a substantial degradation of the track condition as compared to EPref.
    To do this, X is compared to a threshold value, for example to 40 given the coefficients of the table above.
    It should be noted that the threshold value can be reached even before the entire analysis window is taken into account (for example 40 measurements may be sufficient in the event of severe degradation, that is to say AD> 25 ).
    As long as the threshold has not been reached, the next instant is considered by looping on step S355. As soon as the threshold is reached, meaning that the local track condition is significantly degraded with respect to the reference track condition, the reference track condition is updated in step S360 already described.
    In addition, during this step, the counter X is reset to 0, in order to start a new analysis window.
    Figure 5 is a graphic illustration of the evolution of stopping distance and braking level in an operational landing scenario using the invention. This scenario can in particular implement the embodiment of FIGS. 3 and 4, in which the piloting assistance method relies on a plurality of comparisons between predictive and estimated stopping distances of current measurements.
    In this scenario, an aircraft equipped with a flight control system according to the invention, such as that described with reference to FIG. 1, is approaching a track theoretically covered with snow (EPref = COMPACTED SNOW) .
    The braking assistance system 10 takes into account this track state EP and calculates a braking or warning setpoint C (EPref = COMPACTED SNOW) implemented by a braking or restitution device once on the ground during a phase 1. This braking or warning setpoint is based on a stopping distance D (EPref = COMPACTED SNOW).
    During phase 0, the local runway condition turns out to be compacted snow, the aircraft being able to brake at the required setpoint (F = F '- see (c)). Since the aircraft is not in critical braking condition (see (b)), the coefficients CoeffAD (t) are all zero (see (d)). The counter X remains zero, and no change of track condition is operated (S354 negative test).
    During phase 1, the aircraft having advanced on the runway, the local runway condition appears more degraded than the reference runway condition EPref. Indeed, the aircraft does not brake enough (F ') compared to the set point (F): the aircraft is in braking critical condition. The distances D | 0C (t) estimated are therefore greater than the predicted distances D (EPref) (t). During this phase, and after the critical braking condition has lasted a few moments (for example 8 instants), each CoeffAD (t) is worth a positive value in the example of the table above, progressively incrementing the counter χ. When this reaches the threshold value (test S354 positive at the end of phase 1), the track status is updated to the next track state EPmaj = SNOW (see (a)). The aircraft starts phase 2 without critical braking (CoeffAD = 0). Then quickly the track is degraded again, the aircraft putting itself in critical braking (see (b)) which has the effect, after a few moments (8 for example), of adding CoeffAD (t) positive (see ( d)). The degradation of the track being progressive (see the progressive curve F '), the coefficients progressively increase in stages (only three levels have been represented on the figure, whereas in the example of the table above, up to six Bearings can appear according to the progressivity of the curve F 'and according to the final amplitude of AD). The coefficients CoeffAD (t) take a strong value because the degradation of the track is important (EP | 0C = ICY for example).
    The counter X thus increases progressively, and when it reaches the threshold value (positive test S354 at the end of phase 2), the track state is updated to the following track state EPmaj = WrS (see (at)).
    This new track condition is not representative of the local track condition. This is why the aircraft leaves the critical braking state at the beginning of phase 3 (see (b)). As the braking is still insufficient (D | 0C (t)> D (EPref) (t)), the coefficients CoeffAD (t) take a lower positive value with respect to phase 2.
    The counter X thus increases progressively, and when it reaches the threshold value (positive test S354 at the end of phase 3), the track state is updated to the following track state EPmaj = ICY (see (at)).
    During phase 4, the aircraft remains in critical but sufficient braking condition (F = F 'and therefore D | 0C (t) is substantially equal to D (EPref) (t)). The coefficients CoeffAD (t) take a slightly negative value in the example of the table above. The counter X does not reach the threshold value, no change occurs.
    Phase 5 then illustrates the case of an improvement of the conditions of the track. The aircraft leaves the critical braking condition (see (b) because F '> F) and CoeffAD coefficients (t) are then all harmful.
    The foregoing examples are only embodiments of the invention which is not limited thereto.
    权利要求:
    Claims (15)
    [1" id="c-fr-0001]
    1. A method of assisting the piloting of an aircraft during the landing phase, comprising the following steps performed by the aircraft: generating (S320) a reference braking data (D (EPref)) according to a state reference track (EPref); determining local information (D | 0C) according to a local runway condition (EPioc) characterizing a runway area on which the aircraft rolls during landing; when the local information informs of a local condition more degraded than the reference track state, update (S360) the reference track state and generate an updated braking data according to the track condition updated; and supplying the reference braking data and, if necessary, updating the input of a brake assist module (12) capable of generating a braking setpoint (C (EPref)) for controlling a braking device of the aircraft, the method being characterized in that the local information comprises an estimated local stop distance (D | 0C) (S340) from local measurements made in the aircraft, and in that it comprises in addition to the following steps: obtaining (S325) a reference stopping distance (D (EPref) (t)) from the reference braking data, and comparing (S350, S351) the local stopping distance to the reference stopping distance for determining (S354) whether the local track state is more degraded than the reference track state or not.
    [2" id="c-fr-0002]
    The method of claim 1, wherein said comparing comprises comparing (S351) the difference (5D, AD) between the local stopping distance and the stopping reference distance with a predetermined threshold value.
    [3" id="c-fr-0003]
    3. The method of claim 2, wherein the predetermined threshold value is a function of a distance between the aircraft and an end of the runway on which the aircraft rolls during landing.
    [4" id="c-fr-0004]
    The method of claim 2 or 3, wherein the predetermined threshold value is a function of the reference track state.
    [5" id="c-fr-0005]
    5. The method according to claim 1, wherein the determination of whether the local track state (EP | 0C) is more degraded than the reference track state (EPref) or not is a function of a plurality of distances d estimated local stop for a respective plurality of consecutive time instants (t).
    [6" id="c-fr-0006]
    The method of claim 5, wherein the determining comprises a plurality of comparisons respectively between each estimated local stop distance (D | 0C (t)) and a corresponding reference stop distance (D (EPref)). )) estimated from the reference braking data for the same time instant (t).
    [7" id="c-fr-0007]
    The method of claim 6, wherein the determining comprises incrementing (S353) a counter (Σ) when one of said comparisons indicates a difference (AD (t)) between the estimated local stopping distance and the reference stopping distance obtained greater than a predetermined threshold value, and decrementing the counter when the comparison indicates that the difference is smaller than the predetermined threshold value.
    [8" id="c-fr-0008]
    The method of claim 7, wherein the increment or decrement value is a function of said difference (AD (t)).
    [9" id="c-fr-0009]
    The method of claim 7, wherein the predetermined threshold value and / or the increment or decrement value is a function of the reference track state (EPref).
    [10" id="c-fr-0010]
    10. The method of claim 7, wherein the increment or the decrement of the counter is conditioned at a minimum speed (V) of the aircraft and / or the presence, for a predefined duration, of a critical braking condition. of the aircraft corresponding to a braking of the aircraft limited by the friction of the track or the adhesion to the track.
    [11" id="c-fr-0011]
    11. The method of claim 10, wherein the critical braking condition is at least one of: the difference between a commanded deceleration value of the aircraft and a deceleration value measured by the aircraft exceeds a predetermined threshold; the level of manual depression of a brake pedal by an operator exceeds a predetermined threshold; the difference between a controlled braking level of the aircraft and a measured braking level in the aircraft exceeds a predetermined threshold; an anti-skid system of the aircraft is triggered.
    [12" id="c-fr-0012]
    The method of claim 7, wherein the reference track state (EPref) is updated when said counter exceeds a threshold value.
    [13" id="c-fr-0013]
    The method of claim 12, wherein updating the reference track state comprises downgrading the reference track state by one level only among a track state scale.
    [14" id="c-fr-0014]
    14. System (1) for assisting the piloting of an aircraft during the landing phase, the system being embedded in the aircraft and comprising: a module (11) for generating a reference braking data (D ( EPref)) as a function of a reference track state (EPref); a module (20) for determining local information (D | 0C) according to a local track condition (EP | 0C) characterizing a runway area on which the aircraft rolls during landing; a module for updating the reference track state when the local information informs of a local track state more degraded than the reference track state, said generation module (11) being then configured to generate braking data updated according to the updated track condition; and a brake assist module (12) receiving as input the reference braking data then, if necessary, the updated one, configured to generate a braking setpoint for controlling a braking device of the aircraft, the system being characterized in that the local information comprises a local stopping distance (D | 0C) estimated from local measurements made in the aircraft, and further comprising: a module for obtaining a distance of reference stop from the reference braking data; and a comparator (30) for comparing the local stop distance with the reference stop distance to determine if the local runway condition is more degraded than the reference stop distance. reference track condition or not.
    [15" id="c-fr-0015]
    Aircraft comprising at least one flight aid system (1) according to claim 14.
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    同族专利:
    公开号 | 公开日
    FR3045197B1|2018-01-26|
    US20170183086A1|2017-06-29|
    US10293924B2|2019-05-21|
    引用文献:
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    FR2914097A1|2007-03-20|2008-09-26|Airbus France Sas|METHOD AND DEVICE FOR AIDING THE CONTROL OF AN AIRCRAFT DURING A LANDING PHASE|
    FR2930669A1|2008-04-24|2009-10-30|Airbus France Sas|DEVICE AND METHOD FOR DETERMINING A TRACK STATE, AIRCRAFT COMPRISING SUCH A DEVICE AND A PILOTAGE ASSISTANCE SYSTEM UTILIZING THE TRACK STATE|
    FR2936077A1|2008-09-16|2010-03-19|Airbus France|METHOD AND DEVICE FOR AIDING THE CONTROL OF AN AIRCRAFT DURING A LANDING PHASE.|
    US20130127642A1|2010-03-24|2013-05-23|The Boeing Company|Runway Condition Monitoring|
    EP2554443A1|2011-08-01|2013-02-06|Airbus Opérations SAS|Device and method for determining the condition of a runway, aircraft comprising such device and auxiliary control system using this runway condition|
    FR2978736A1|2011-08-01|2013-02-08|Airbus Operations Sas|DEVICE AND METHOD FOR DETERMINING A TRACK STATE, AIRCRAFT COMPRISING SUCH A DEVICE AND A PILOTAGE ASSISTANCE SYSTEM UTILIZING THE TRACK STATE|
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    US20190263511A1|2018-02-23|2019-08-29|The Boeing Company|Methods and apparatus for controlling landing gear retract braking|
    US10933982B2|2018-02-26|2021-03-02|The Boeing Company|Methods and apparatus for controlling landing gear retract braking|
    FR3078811B1|2018-03-06|2020-04-03|Dassault Aviation|METHOD FOR DYNAMICALLY DETERMINING THE POSITION OF THE STOP POINT OF AN AIRCRAFT ON A RUNWAY, AND ASSOCIATED SYSTEM|
    GB2588579A|2019-10-09|2021-05-05|Airbus Operations Ltd|Speed determination system|
    法律状态:
    2016-12-22| PLFP| Fee payment|Year of fee payment: 2 |
    2017-06-16| PLSC| Search report ready|Effective date: 20170616 |
    2017-12-21| PLFP| Fee payment|Year of fee payment: 3 |
    2019-12-19| PLFP| Fee payment|Year of fee payment: 5 |
    2020-12-23| PLFP| Fee payment|Year of fee payment: 6 |
    优先权:
    申请号 | 申请日 | 专利标题
    FR1562246|2015-12-11|
    FR1562246A|FR3045197B1|2015-12-11|2015-12-11|IMPROVED METHOD AND SYSTEM FOR AIDING THE CONTROL OF AN AIRCRAFT IN THE LANDING PHASE|FR1562246A| FR3045197B1|2015-12-11|2015-12-11|IMPROVED METHOD AND SYSTEM FOR AIDING THE CONTROL OF AN AIRCRAFT IN THE LANDING PHASE|
    US15/372,039| US10293924B2|2015-12-11|2016-12-07|Method and system for assisting the piloting of an aircraft in landing phase|
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