Patent Application
20230192312
This application is the U.S. national phase of International Application No. PCT/EP2021/062593 filed May 12, 2021 which designated the U.S. and claims priority to FR Patent Application No. 20 04702 filed May 13, 2020, the entire contents of each of which are hereby incorporated by reference.
The present invention relates to the field of piloting an aircraft for the maneuver of aligning the aircraft heading with the axis of the runway during the final landing phase. The difficulty of performing the maneuver increases with the intensity of the crosswind, which can then lead to exiting the runway or damage to the landing gear.
During the landing phase of an aircraft in the presence of crosswind, the longitudinal axis of the aircraft (herein also called heading) is oriented toward the origin of the wind while the trajectory of the aircraft (herein also called route) is the trajectory of the runway centerline. The angle thus formed between the heading and the route, called drift, is proportional to the intensity of the crosswind. A few seconds before landing the aircraft, the pilot has to partially align the aircraft heading so as to reduce the forces on the landing gear during the contact with the ground and so as to prevent the aircraft from subsequently having a tendency to deviate from the runway centerline. The pilot has to do such maneuver while performing a flare of the vertical trajectory (in order to decrease the vertical speed at impact) and while maintaining the trajectory of the aircraft along the runway centerline.
Such complex maneuver has to be performed within a short time and ideally in a single movement on the control units. In this way, little time is left for the pilot to make any corrections, if appropriate, in the event of poor maneuvering or of a gust of wind.
Moreover, during such phase, the pilot should have the eyes directed toward the outside of the cockpit in order to visually acquire the runway markings which would enable the pilot to touch down safely. The use of display for piloting information in the field of view of the pilot is then a considerable help. To overcome the disadvantage of fixed displays along the axis of the aircraft, such as “Head Up Display (HUD)”, it is now possible to use displays worn by the head of the pilot “Head Worn Display (HWD)”. In fact, in the event of a strong crosswind, the drift can be greater than the field of view of such display, so the pilot may not see the runway through the display. The head-worn display then allows the pilot to turn the head toward the runway while keeping the piloting information. However, in the presence of crosswind with such type of head-worn display, the pilot can then minimize their perception thereof of the difference between the heading and the runway centerline and no longer be aware of the need for the alignment maneuver. Indeed, the pilot would naturally turn their head toward where they want to go, i.e. the runway, and not along the axis of the aircraft.
Currently, there is no display of a dedicated indicator in the cockpit for assisting the pilot in such alignment maneuver. In the event of a crosswind, a poor maneuver can lead to exiting the runway or to damage to the landing gear. A correct maneuver is based either on the know-how of the pilot or on an automatic system which performs the maneuver instead of the pilot.
Most head-up displays can now provide heading, route and runway centerline information.
U.S. Pat. No. 10,460,613 e.g. proposes a display of three symbols: the first is an indication of alignment with the runway centerline, the second is an indication of the aircraft heading and the third is an indication of the route of the aircraft with an indication of the trend of the evolution of same route. Such symbols can also be used during the intercept phase of the runway centerline.
However, it remains necessary to assist the pilot in performing the maneuver. Moreover, such solutions do not solve the minimization of the pilot's perception of the difference between the heading and the runway centerline with a head-worn display and [the problem of] no longer being aware of the need for the alignment maneuver.
To this end, according to a first aspect, the invention proposes an electronic device for guiding the pilot in the piloting of an aircraft for performing the alignment maneuver of the longitudinal axis of the aircraft with the runway centerline during the landing of said aircraft in the presence of a crosswind,
said device being suitable for determining at a first instant, an occurrence close to the alignment maneuver and to trigger, upon said determination of the near occurrence, a first display command controlling the appearance, on a display medium intended for the pilot and displaying the horizon graduated according to a heading scale, of at least one first symbol at a specified position on the display medium with respect to the graduation of the horizon line;
said device being suitable for updating the current position of the first symbol on the horizon depending on the updated value of the aircraft heading;
said device being suitable for determining, at a second instant strictly following said first instant, that the alignment maneuver should now begin and then for triggering a second display command controlling a movement of a second symbol on the display medium, from the position of the first symbol, the direction of said displacement with respect to the horizon being determined depending on the direction of the crosswind with respect to the runway, and the value of the displacement being determined depending on the difference between the current dynamic sideslip of the aircraft and a current dynamic sideslip setpoint value calculated for the aircraft, said current dynamic sideslip corresponding to the angle between the current air speed of the aircraft and the current heading of said aircraft.
The invention thus makes it possible to indicate the appropriate instant and the way of performing the alignment maneuver.
In some embodiments, a method of controlling according to the invention further includes one or more of the following characteristics:
According to a second aspect, the present invention proposes a method of guiding the pilot in the piloting of an aircraft for performing the maneuver of alignment of the longitudinal axis of the aircraft with the runway centerline during the landing of said aircraft in the presence of a crosswind, using an electronic guiding device implementing the following steps:
In some embodiments, a method of guiding according to the invention further includes one or more of the following features:
According to a third aspect, the invention further relates to a computer program including software instructions which, when executed by a computer, implement a method as defined hereinabove.
The features and advantages of the invention will appear upon reading the following description, given only as an example, and making reference to the enclosed drawings, wherein:
An aircraft 1, herein an aircraft 1 implementing the invention 1 is shown in
During a crosswind approach (i.e. a wind [blowing] in a direction not parallel to the runway), represented by the arrows 4 in
Compared to air, the aircraft 1 flies with a speed vector called TAS (True Air Speed). The air is moving according to the speed vector, called wind speed W. Finally, the aircraft 1 moves with respect to the ground with a speed vector, known as Ground speed Vs.
When the crosswind is strong, the pilot of the aircraft 1 has to reduce the drift angle so as to reduce the lateral force on the landing gear and to obtain a taxiing trajectory along the runway centerline so as to avoid exiting the runway. Indeed, once in contact with the ground, the tires of the landing gear will create significant forces that the landing gear will have to withstand and which will greatly modify the trajectory of the aircraft.
Before landing, the pilot will have to reduce the gap between the aircraft heading and the orientation of the runway, i.e. perform an alignment maneuver between the two axes, by creating the aerodynamic sideslip—
The aerodynamic sideslip is performed by the pilot via pedals moving a movable surface on the vertical empennage and giving rise to aerodynamic sideslip.
During such same final phase before landing, the pilot has to further perform a flare. Such maneuver consists in raising the nose of the aircraft in order to decrease the vertical speed of the aircraft on impact. There are currently aids for performing such maneuver, called “Flare Cue” or “Flare Prompt”.
In one embodiment, with reference to
The display system 60 includes a display support, typically a screen, and is suitable for displaying on the display support, fixed with respect to the aircraft or mobile by following the head movements of the pilot, in a known manner, information intended for the pilot during such phase.
The display system 60 is e.g. in the present case, a HUD (head-up) or HWD (head-worn) display system
In particular, the display system 60 is suitable for displaying on the display medium intended for the pilot, as is known and as represented in
This information is provided by a number of equipment items on board the aircraft, based on measurements and/or calculations.
According to the invention, the piloting assistance system 52 is suitable for displaying on the display medium of the display system 60, a set of two additional marks in addition to said information, so as to guide the pilot in the alignment maneuver thereof during the landing phase.
In the present case, the set of two marks includes a parameter reminder mark and an alignment assistance mark.
The commands triggering the display of such marks and defining the positions thereof are provided by the guiding device 50 shown in
In one embodiment, the guiding system 50 includes a processor 53 and a memory 54.
The memory 54 comprises software instructions which, when executed on the processor 53, automatically implement the steps belonging to the processing device 50 described with reference to
In a first step 101, a few seconds (e.g. between 2 and 10 seconds) before the estimated start of the alignment maneuver, the guiding device 50 commands the display of the two marks at the same point on the display medium (the marks can be completely superimposed or slightly offset from each other).
The position of the point recalls the value of the parameter considered and depends on the angular difference between the aircraft heading (i.e. the longitudinal axis thereof) and the runway centerline.
Such display warns the pilot, in advance of the phase, of the imminence of the alignment maneuver and thus tells the pilot to prepare to perform said maneuver.
In a second step 102 triggered by the guiding device 50 at the instant when the alignment maneuver by the pilot is to begin, the guiding device 50 controls e.g. a change of appearance in the display of one and/or the other of the two marks (e.g. the display becomes flashing or stops flashing and/or changes from fine or dotted lines to bold or solid lines, etc.), the guiding device 50 then controls a displacement on the display medium of the alignment assistance mark depending on the difference between the actual dynamic sideslip of the aircraft and a calculated dynamic sideslip setpoint for the aircraft.
The second step thus makes it possible to clearly alert when the maneuver should begin and [when] to display the direction and the dynamics (the speed) with which the maneuver has to be performed.
The movement of the alignment assistance mark on the display medium then controlled by the guiding device 50 indicates to the pilot the dynamics to be followed by the parameter reminder mark in order to perform the maneuver correctly, the position of the parameter reminder mark being always dependent on the angular difference between the aircraft heading (i.e. the longitudinal axis thereof) and the runway centerline.
Indeed, the goal for the pilot is, in the second step, to implement the alignment by performing an aerodynamic sideslip via the pedals, such that the parameter reminder mark (which moves on the display support according to the maneuver) stays superimposed on the alignment assistance mark (the latter moving according to the difference, updated in real time, between the current sideslip of the aircraft and the sideslip setpoint also updated in real time).
In a first embodiment, the parameter reminder mark is an aircraft heading reminder mark.
In a second embodiment, the parameter reminder mark is an aircraft sideslip reminder mark.
Such embodiments, and some of the possible variants thereof, are now described in greater detail with reference to
Moreover, it should be noted that the direction of the wind, in the situations illustrated in the
The heading reminder mark 30 (“heading carrot”) of the aircraft 1 is displayed herein above the horizon line 20 (same can be displayed, depending on the embodiments, above or below the horizon line, whether or not attached to the latter) The mark indicates the current value of the aircraft heading and is positioned, along the horizon line, relative to the orientation of the runway centerline 29, i.e. depending on the angular difference between the aircraft heading 1 and the runway centerline 29 (the runway symbol (the rectangle above the runway centerline) is placed where the runway is located; thus, if the aircraft is heading toward the runway, but from a direction different from the runway centerline, then the symbol 29 is not aligned with the orientation of the runway centerline on the heading scale; the heading reminder symbol is placed relative to the orientation of the runway on the horizon heading scale).
In the embodiment shown in
Optionally, during the steps 101, 102, the position of the heading reminder mark can be not according to the heading scale 20, so as to remain visible on the display even in the event of a strong crosswind while the head of the pilot is facing the runway.
A scale factor, with a calculated value between [0, 1] then applies, upon command from the guiding device 50, on the difference between the aircraft heading and the runway orientation and in such a case, as shown in
The alignment assistance mark in step 102 tells the pilot how to move the heading reminder mark to properly perform the maneuver. Such alignment assistance mark is referenced by 31 in
It is the guiding device 50 which indicates in the command thereof, during the steps 101 and 102, whether a scale factor k different from 1 has be taken into account in the display of the two marks according to the invention and in such case, the guiding device 50 indicates the value of k therein.
As introduced above, in a second embodiment illustrated in
The guiding device 50 controls, during the step 101, the display of the sideslip reminder mark 40 of the aircraft below the ground speed vector 23 (“FPV”). At such instant, the value of the sideslip is zero.
The alignment assistance mark, referenced by 41 in
Like in the first embodiment, the alignment assistance mark 41 thus indicates to the pilot how the pilot should move the other mark, herein the sideslip reminder mark 40 so as to correctly perform the alignment maneuver. In the example shown in
It should be noted that in another embodiment, the guiding device 50 could also move the alignment assistance to the right to indicate to the pilot to press to the right, and then the sideslip would shift to the left and it is the alignment assistance which would recenter on the sideslip reminder.
The goal for the pilot in the maneuver thereof is to perform the latter in such a way as to keep the two markers superimposed on each other.
In one embodiment, the time of appearance of the marks (step 101) is determined by the guiding device 50 depending on the height of the aircraft 1 with respect to the ground, called the radio height, measured e.g. by an altimetric radio probe, of the vertical speed of the aircraft, called Speedvertical, and a predefined threshold, called HeightAppearance, as follows:
as soon as HeightRadio+t·Speedvertica<HeightAppearance, the triggering of step 101 (t is a constant with a determined value, with the value being comprised between 2 and 10 seconds).
Optionally, the vertical speed can be averaged and filtered in order to eliminate the variations due to aerodynamic turbulence and to trajectory adjustments made by the pilot.
Alternatively, the instant of appearance can be determined depending on the distance to the runway threshold, e.g. measured by a DME or GPS block, called DistanceDME/GPS, of the ground speed of the aircraft, called Speedground, and of a predefined threshold, called DistanceAppearance, as follows:
as soon as DistanceDME/GPS+t′·>Speedground<DistanceAppearance, the triggering of step 101 (t′ is a constant with determined value, the value being comprised between 2 and 10 seconds).
In the embodiment considered, the distance of the displacement of the alignment assistance mark 31, 31′, 41, with respect to the parameter (heading or sideslip) reminder mark 30, 30′, 40 on the display medium controlled during the step 102, is determined by the guiding device 50 depending on the difference between the current aerodynamic sideslip of the aircraft, β, and the current sideslip setpoint, βsetpoint.
The displacement between the two marks is e.g. proportional to such difference. The relationship e.g. may not be proportional, but follows a rising curve, i.e. the displacement increases when the difference increases.
The difference is calculated as follows:
Δaff=kaff·(β−βsetpoint)
The current value of the aerodynamic sideslip β can be obtained by the guiding device 50 in a plurality of ways:
a measurement with a sideslip probe,
an estimate based on inertial measurements (lateral acceleration, lateral inclination and pitch, roll and yaw rate, etc.), air speed measurement (TAS), the difference in static pressure measurements and optionally the position of movable surfaces (especially rudder, etc.) which generate lateral forces,
a hybridization between the previous 2.
In the case considered, the sideslip setpoint β is obtained depending on the sum of the current sideslip (β) and the difference (angle) between the aircraft heading (“heading”) and the orientation of the runway centerline (“Course”), e.g. proportionally to said sum:
βsetpoint=kalign·(β+(Heading−Course))
The align proportionality factor kalign allows the residual drift to be adjusted. Optionally, such setpoint can be delayed/filtered and limited in speed and amplitude so as to be representative of the actual behavior of the aircraft.
The relationship between the heading difference and the set point e.g. may not be proportional, but follows a rising curve in order to better take physical non-linearities into account.
Advantageously, at the same time, the flight director (FPD) is modified laterally so as to indicate the corrections to be made on the side handle in order to maintain the trajectory of the aircraft along the axis.
In addition to a lateral difference, the flight director sometimes presents a lateral inclination setpoint in the form of small wings (See
The 2 effects on the flight director are controlled directly by the relationship between the aerodynamic sideslip and the lateral inclination necessary for maintaining a rectilinear flight.
The invention makes it possible to warn the pilot of the imminence of the maneuver by the appearance of two symbols in the same place on the display. The start time of the maneuver is identified by the change in appearance of said symbols and the setting in motion of the guiding symbol. The latter then indicates the dynamics to be followed by the other symbol so as to perform the maneuver correctly. The pilot then acts on the pedals so as to follow said movement.
On the other hand, the flight director symbol further provides an indication of the roll angle and the commands to be applied to the lateral control element (handle or handwheel) necessary for compensating for the tendency of variation of the route, as introduced by such maneuver.
The invention thus provides assistance in piloting aircraft during the landing phase. In some embodiments, the assistance is integrated into a display system for aircraft flight control stations (head-down, fixed head-up and head-worn screens) or further into a system of flight assistance/guiding (automatic pilot, flight director, AFCGS “Auto Flight Control and guiding System”).
Hereinabove, the appearance of the two marks during the step 101, in a superimposed manner, has been described; of course, in another embodiment, only the first mark is displayed during the step 101; the second mark is displayed during the step 102.
In another embodiment, the processing blocks 50 is produced in the form of a programmable logic component, such as an FPGA (Field Programmable Gate Array), or further in the form of a dedicated integrated circuit, such as an ASIC (Application Specific Integrated Circuit).
The invention has been described hereinabove in relation to an aircraft, but same can be applied to any type of aircraft, in particular having to touch down with a non-zero speed.
| Number | Date | Country | Kind |
|---|---|---|---|
| 20 04702 | May 2020 | FR | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/EP2021/062593 | 5/12/2021 | WO |
