Method and device for piloting an aircraft with a head-up display

Abstract

The present invention relates to a method for piloting an aircraft (1) comprising a head-up display (30) and an autopilot system (20) which includes a human-machine selection interface (20) for choosing an operating mode from among several predetermined operating modes including a disengaged mode and an engaged mode, the autopilot system (20) being configured in the engaged mode to control at least one actuator (25) in order to make a current value of a piloted parameter (PAR) tend towards a setpoint value.The method comprises: i) detection, using a control system (40), of a current mode applied from among several predetermined operating modes; ii) control and display on the head-up display (30) of a symbol bearing said current value according to a graphic charter specific to the current mode, a first graphic charter applied during the disengaged mode being different from a second graphic charter applied during the engaged mode. Abbreviated figure: Figure 1.

Description

Title of the invention: Method and device for piloting an aircraft with a head-up display

[0001] The present invention relates to a method and device for piloting an aircraft with a head-up display.

[0002] An aircraft may be equipped with various displays to show information useful to an operator. In addition, an aircraft may include an autopilot system capable of piloting the aircraft so that at least one flight parameter tends towards a setpoint value.

[0003] The term “operator” can refer to a pilot, a co-pilot, or even any person operating in a cockpit.

[0004] The term “information” may refer to symbols which include, for example, geometric shapes, numbers, letters, these symbols being able to vary over time and being able to represent physical quantities or objects in particular.

[0005] Among this information, a person skilled in the art distinguishes between so-called "primary" information and so-called "secondary" information. Primary information relates to short-term piloting information, or even essential piloting information. Secondary information includes all other displayable information and, for example, meteorological data, route planning data, etc.

[0006] To present this various information to an operator, an aircraft may include one or more displays described as "head-down." A head-down display is visible to an operator when that operator directs their gaze downwards and into the cockpit. A head-down display may, for example, be mounted on an instrument panel or even a console.

[0007] For the record, when the operator directs their gaze upwards and outwards from the aircraft, and therefore particularly towards the environment above an instrument panel and console, a person skilled in the art considers that this operator is in a "head-up" position. Conversely, when the operator looks inside the aircraft, and in particular at the instrument panel or console, a person skilled in the art considers that this operator is in a "head-down" position.

[0008] A heads-up display may, for example, include a "screen". In particular, a multifunction display may display various pages that can contain various information. Thus, a multifunction display may display one or more pages containing primary and / or secondary information. The operator can choose which page to display.

[0009] To access the information displayed on such a head-down display, an operator must regularly look into the cockpit. However, when the aircraft is near terrain or an obstacle, for example during a winch or rescue operation, a pilot frequently looks outside the cockpit to detect potential hazards. Thus, frequently consulting a head-down display in such a situation increases the pilot's workload and may even increase the risk of an accident.

[0010] Documents EP 3454016 and EP 3869158 disclose head-down displays.

[0011] To solve this problem, an aircraft may also include a head-up display to present important information to an operator when that operator is in the head-up position.

[0012] For example, a head-up display may include a screen on a helmet worn by a pilot, a retinal projection means, a windshield projection means, or a device known by the English expression "Head Up display" or its acronym HUD. A head-up display may include, for example, a system called "head mounted display" in English, a system called "head wom display" in English, a system called "near eye display" in English, or a system called "Helmet Mounted Display" when the system is mounted on a helmet, or even a system called, for example, "Helmet Mounted Sight & Display".

[0013] Regardless of how a head-up display is implemented, this head-up display can reduce a pilot's workload by eliminating the need to consult head-down displays. The information displayed on the head-up display is superimposed on the external view, where the pilot obtains the visual references essential for visual piloting of the aircraft. To illustrate this, during a winch operation, a pilot can access the head-up information by observing the scene below through a windshield. The pilot then does not need to look inside the cockpit.

[0014] Furthermore, the head-up display can collimate the displayed images to infinity or at least to a distance much greater than the distance between the pilot or co-pilot and the instrument panel. The pilot or co-pilot therefore does not need to refocus their eyes to switch from looking outside to reading the information displayed on the head-up display. This feature reduces user fatigue and the time required to access the displayed information.

[0015] The head-up display also allows information to be displayed superimposed on the external environment: Those skilled in the art refer to this as conformal information. For example, a symbol can be positioned at the precise location of the point predetermined landing.

[0016] A head-up display is therefore advantageous. However, the information displayed must be limited. Indeed, displaying a large amount of information on the head-up display can ultimately prevent the user from properly distinguishing the external environment, which would be contrary to the purpose of the head-up display. Thus, the information displayed on a typical head-up display is generally limited to essential piloting information and often does not include the useful information related to an autopilot system.

[0017] Indeed, a pilot may, for example, have autopilot engaged to maintain level flight. The pilot may maneuver the aircraft controls to change flight level, for example, to avoid an obstacle. When the pilot releases the controls, the autopilot system becomes active again. The pilot may have forgotten that the autopilot system is engaged and may be surprised by the aircraft's behavior resulting from the resumption of autopilot.

[0018] By way of example, a head-down display may present an image comprising an airspeed indicator, a heading compass rose, a barometric altitude indicator, and an artificial horizon. In addition, this image may contain symbols relating to an active autopilot system, such as a target airspeed value, a target heading value, and a target altitude value, an index pointing to the target airspeed on the airspeed indicator, an index pointing to the target heading on the heading compass rose, and an index pointing to the target altitude on the barometric altitude indicator.

[0019] Conversely, the head-up display simply presents an image including a speed indicator, a heading scale, a barometric altitude indicator, and a symbol displayed in a conforming manner and carrying the air direction vector of the aircraft.

[0020] In another respect, a head-up display can be monochrome, which limits the possibilities for conveying information visually. Furthermore, a head-up display may have a restricted display area, generally circular / elliptical or potato-shaped, unlike the rectangular screen of a head-down display.

[0021] The webpage www.code450.com / heads-up-display displays a monochrome head-up display. This display presents a great deal of information, including a banner indicating the activated autopilot modes. The field of vision is relatively cluttered.

[0022] The report "Symbolology of Head-Up Collimators - Pre-Regulatory Study for SFACT" dated 2002 and available on the webpage www.headupflight.net / documents / hudf.pdf presents a head-up collimator presenting various pieces of information during an approach.

[0023] Document FR 3038380 describes a display including a slope symbol, a slope scale, constraint symbols and a guidance instruction according to the slope scale.

[0024] These documents are interesting but show displays presenting symbols dedicated to instructions which in fact load the field of vision of an operator.

[0025] The present invention then aims to propose an innovative method for optimizing the workload of an aircraft operator, and in particular of a pilot.

[0026] The present invention thus relates to a method for piloting an aircraft comprising a head-up display and an autopilot system, the autopilot system comprising a human-machine interface for selecting an operating mode from among several predetermined operating modes comprising a disengaged mode and an engaged mode in order to require autopilot of at least one parameter, the autopilot system being configured in the engaged mode to control at least one actuator of the aircraft in order to make a current value of said parameter tend towards a setpoint value.

[0027] This process comprises the following steps:

[0028] - detection with a control system of a current mode applied among said several predetermined operating modes,

[0029] - control of the head-up display with the control and display system on the head-up display of a symbol bearing said current value according to a graphic charter specific to the current mode to visualize the current mode, a first graphic charter applied during the disengaged mode being different from a second graphic charter applied during the engaged mode.

[0030] This method can be implemented for one or more parameters that can be controlled by the autopilot system, and for example for aircraft altitude, aircraft heading, aircraft indicated airspeed, aircraft flight path vector, and / or hovering. The flight path vector may be called the "Flight Path Vector" and may be represented by a suitable symbol.

[0031] The term "graphic charter" refers to the way in which the symbol is displayed, for example by covering the shape of an object in the symbol and / or the thickness of one or more lines in the symbol and / or the presence or absence of a border or underline of an object in the symbol. The symbol illustrating a current value of a parameter may include an object displaying at least one digit, at least one letter, a scale associated with at least one number and / or a cursor, this object being able to be framed or underlined.

[0032] This method thus proposes to display a single symbol that conveys both the current value of the parameter in question and the operating mode of the autopilot system with respect to that parameter. When the symbol has a first appearance defined by the first graphic charter, an operator deduces that the associated operating mode is disengaged, meaning the autopilot system is not controlling that parameter. Conversely, when the symbol has a second appearance, different from the first and defined by the second graphic charter, an operator deduces that the associated operating mode is engaged, meaning the autopilot system is controlling that parameter.

[0033] From a "Human" point of view, updating the visual appearance of a symbol, for example by changing its shape or by adding a frame or underlining or even thickening a line, is sufficient to update the mental representation that an operator constructs with respect to the current operating modes of the automatic piloting system.

[0034] Consequently, the method allows an operator to easily determine, even on a monochrome head-up display, and while significantly limiting the obscuring of part of the external environment, the current operating mode of the autopilot system with respect to one or more parameters. The method does not require the display of a symbol dedicated to autopilot, such as a standard autopilot information banner, or the display of one or more instructions as such, to determine the current operating mode.

[0035] The method thus has a limited impact on an operator's field of vision by not necessarily adding symbols when the autopilot system is active. The workload of a pilot, for example, is thereby simplified since the pilot does not need to consult a head-down display or a head-up display overloaded with information. Flight safety can therefore be increased.

[0036] The method may also include one or more of the following features.

[0037] According to one possibility, for the same current value, the symbol can be in the same position on the head-up display regardless of the current mode.

[0038] The same symbol takes on different appearances when the operating mode of the autopilot system changes, but does not move on the head-up display. The invention provides a single symbol that changes its appearance, unlike systems with two separate and independent symbols, one displaying a current value of a parameter and the other a setpoint.

[0039] According to a possibility compatible with the preceding ones, said symbol may include an object according to the first graphic charter, said symbol including said object and a frame surrounding at least partially the object according to the second graphic charter.

[0040] Such an object may take the form, for example, of a number, or of a scale associated with a slider and / or a number. The presence of a frame can be easily identified by an operator in order to determine the current operating mode with respect to the parameter being examined.

[0041] According to another possibility, said symbol may include a first object according to the first graphic charter, said symbol including according to the second graphic charter a second object visually different from the first object.

[0042] The first and second objects can take the form, for example, of a number, a particular geometric shape, or a scale associated with a slider and / or a number. Depending on the object displayed to show the current value of a parameter, an operator can easily deduce the current operating mode with respect to that parameter.

[0043] For example, the first object may have a first geometric shape, the second object having a second geometric shape, the second shape being visually different from the first shape.

[0044] By way of illustration, a symbol accurately representing an aircraft flight direction vector may typically consist of a circle and two aligned segments on either side of the circle when the flight direction vector autopilot is disengaged. In engaged mode, the circle may be replaced by a diamond, for example. An operator can thus easily determine whether the flight direction vector autopilot is engaged or not.

[0045] In a complementary or alternative manner, the first object and the second object may include at least one of the same feature, the feature having a first thickness in the first object, the feature having in the second object a second thickness greater than the first thickness.

[0046] According to the preceding example, a symbol accurately representing an aircraft flight direction vector may typically consist of a circle and two segments aligned on either side of the circle when the flight direction vector autopilot is disengaged. In engaged mode, the segments may be drawn with thicker lines, and the circle, or the rhombus replacing it if applicable, may also be drawn with such thick lines. An operator can thus easily determine whether the flight direction vector autopilot is engaged or not.

[0047] According to a possibility compatible with the preceding ones, said several operating modes may include an armed mode during which said setpoint value is parameterized, provided that the current mode is the armed mode then said method may include a control of the head-up display with the control system and a display on the head-up display of said symbol according to a third graphic charter different from the first graphic charter and the second graphic charter.

[0048] Thus, an operator can know if an autopilot mode is disengaged, armed or engaged with the symbol bearing the current value of the parameter concerned.

[0049] According to a possibility compatible with the preceding ones, during a change of mode to switch from an old mode to a new mode chosen from said several operating modes, said method may include a control of the head-up display with the control system and a display on the head-up display of said symbol, for a predetermined transitional period, alternately according to the graphic charter of the old mode and the graphic charter of the new mode.

[0050] This feature makes it possible to draw the attention of an operator to indicate that the autopilot system is changing its operating mode for the parameter concerned, again without adding a dedicated symbol.

[0051] According to a possibility compatible with the preceding ones, the method may include a detection that the current value is different from the setpoint value, and provided that the current value is different from the setpoint value, the method may include a control of the head-up display with the control system and a display on the head-up display of the setpoint value opposite said symbol.

[0052] The setpoint value can be in the immediate vicinity of the associated symbol. Optionally, a segment can connect the setpoint value and the symbol so that an operator can immediately link the setpoint value to the parameter in question.

[0053] Optionally, this feature allows an operator to know in addition whether the setpoint of the automatic piloting system has been reached.

[0054] Optionally, the setpoint value can be placed in the eyes of an operator above the symbol when the setpoint value is greater than the current value and below the symbol when the setpoint value is less than the current value.

[0055] This feature allows an operator to know in addition whether the setpoint is greater than or less than the current value of the parameter.

[0056] Optionally, a segment extends from the setpoint value to the associated symbol.

[0057] Optionally, a distance separating the setpoint value and the associated symbol varies according to a difference between the setpoint value and the current value of the parameter in question. This distance can be obtained using a law that gives the distance solely as a function of the aforementioned difference.

[0058] Thus, this setpoint value gradually shifts as it approaches (respectively: moving away) from the current value as the aircraft approaches (respectively: moving away) from said setpoint. If necessary, the segment shortens (respectively: lengthens) in accordance with the translation.

[0059] Thus, the positioning of the setpoint value relative to the associated symbol carries the numerical difference between this setpoint value and the current value carried by this symbol.

[0060] In addition to a method, the invention relates to an aircraft implementing this method.

[0061] Such an aircraft includes a head-up display and an autopilot system, the autopilot system including a selector human-machine interface for choosing an operating mode from among several predetermined modes including a disengaged mode and an engaged mode in order to require autopilot of at least one parameter, the autopilot system being configured in the engaged mode to control at least one actuator of the aircraft in order to make a current value of a piloted parameter tend towards a setpoint value, said aircraft including a control system for controlling said head-up display.

[0062] The control system and the head-up display are then configured to apply the method of the invention. In particular, the head-up display can be monochrome.

[0063] The invention and its advantages will become apparent in more detail in the following description, with illustrative examples given by reference to the accompanying figures, which represent:

[0064] [Fig. 1], a diagram illustrating an aircraft according to the invention,

[0065] [Fig.2], a diagram showing a head-down display of the aircraft,

[0066] [Fig. 3], a diagram illustrating the process of the invention,

[0067] [Fig. 4], a diagram showing a head-up display of an aircraft according to the invention to illustrate the method of the invention, and

[0068] the [Fig.5], a diagram showing a head-up display of an aircraft according to the invention to illustrate the method of the invention.

[0069] Elements present in several separate figures are assigned one and the same reference.

[0070] Figure 1 shows an aircraft 1 of the type of the invention, such as an airplane or a rotorcraft. Only the components of aircraft 1 that have a direct connection with the invention are illustrated so as not to unnecessarily clutter Figure 1.

[0071] This aircraft 1 has a cockpit 5 in which there is at least one operator 6.

[0072] This aircraft 1 includes an autopilot system 20. Such a system of Autopilot 20 is sometimes referred to as AFCS, the acronym AFCS corresponding to the English expression "Automatic Flight Control System".

[0073] The autopilot system 20 includes at least one actuator 25 for piloting the aircraft 1 to move the current value of a PAR parameter towards a setpoint value. For example, on a rotary-wing aircraft, an actuator can be extended, retracted, or rotated to change the pitch of the rotary-wing blades. This example is given simply to illustrate the invention.

[0074] The actuator(s) may be controlled by an automatic control unit 21 connected by wired or wireless links to the actuator(s) 25. The automatic control unit 21 may include, for example, at least one processor and at least one memory, at least one integrated circuit, at least one programmable system, at least one logic circuit, these examples not limiting the scope given to the term "control unit". The term "processor" may refer to a central processing unit known by the acronym CPU, a graphics processing unit GPU, a digital signal processing unit known by the acronym DSP, a microcontroller...

[0075] Furthermore, this automatic piloting system 20 can be equipped with a human-machine control interface connected by a wired or wireless link to the automatic piloting computer 21 in order to set the value(s) of the setpoint(s).

[0076] Furthermore, the autopilot system 20 is connected to one or more sensors directly or via at least one avionics computer through a communication network link. The sensor(s) allow for the estimation of the current value(s) of the parameter(s) that can be controlled by the autopilot system 20. Each sensor generates a signal, for example, digital or analog, electrical or optical, relating to at least one parameter. Each sensor may include a sensor capable of directly measuring the parameter in question, as well as a system that may include one or more physical sensors and signal processing means for providing an estimate of the parameter from the measurements provided by this or these sensors.

[0077] By way of illustrative example, aircraft 1 may include a speed sensor 46 for measuring a PAR parameter of the indicated airspeed (IAS) type. Such a speed sensor 46 may include, for example, an anemometer.

[0078] The aircraft 1 may include an altitude sensor 47 for measuring a PAR parameter of the altitude type ALT. Such an altitude sensor 47 may include, for example, a radio altimeter.

[0079] Aircraft 1 may include a heading sensor 48 for measuring a PAR parameter of the heading CP type. Such a heading sensor 48 may include, for example, a compass.

[0080] The aircraft 1 may include a flight direction vector sensor 49 for measuring a PAR parameter of the flight direction vector type VVIT. Such a flight direction vector sensor 49 may include, for example, an inertial measurement unit.

[0081] Furthermore, the autopilot system 20 is equipped with a selection human-machine interface 22 allowing the operator 6 to choose an autopilot mode, more simply called an operating mode, for one or more PAR parameters. This operating mode can be either a disengaged mode, an engaged mode, or even an armed mode. When the disengaged mode is activated for a parameter, the autopilot system does not perform any action for that parameter. When the armed mode is activated for a parameter, a setpoint value can be configured. When the engaged mode is activated to maintain a PAR parameter, the autopilot system 20, and in particular the autopilot computer 21, is configured to control at least one actuator 25 in order to move the value of the PAR parameter, evaluated with the required sensor(s), towards a setpoint value.

[0082] Furthermore, aircraft 1 is equipped with displays to present various information to the eyes 7 of the operator 6.

[0083] In particular, the aircraft 1 may include a head-down display 10 visible to the operator 6 when their gaze follows a head-down line of sight VSTB. The head-down display 10 is optionally mounted on a console or instrument panel 11. Such a head-down display 10 may include a screen, and for example a multifunction display known by the acronym MFD and the English expression "Multi Functions Display".

[0084] With reference to [Fig.2], such a head-down display 10 can present an image including a lot of information, and for example a speed indicator 101 showing where appropriate a speed setpoint 102, a heading rose 103 showing where appropriate a heading setpoint 104, a barometric altitude indicator 105 showing where appropriate an altitude setpoint 106, an artificial horizon 108, and an autopilot strip 110 showing the engaged autopilot modes and associated setpoint values.

[0085] In addition, the aircraft 1 includes a head-up display 30 and a control system 40 for controlling this head-up display 30. The control system 40 is configured to transmit a signal to the head-up display 30, the head-up display 30 displaying one or more symbols upon receiving this signal. Optionally, the head-up display 30 is monochrome. The head-up display 30 then displays symbols in a single color, usually green.

[0086] The head-up display 30 can be fixed, for example of the HUD type, or can be worn. The head-up display 30 can be of a common type, and for example can be a system called a "head-mounted display" in English, a system called a "head-worn display," a system called a "near-eye display" in English, a system called a "helmet-mounted display" when mounted on a helmet, or again for example “Helmet Mounted Sight & Display”.

[0087] The head-up display 30, or even the head-down display 10, can be controlled by a computer referred to for convenience as the "display computer 45". A display computer 45 is thus connected by a wired or wireless connection to the head-up display 30 or even to the head-down display 10. Optionally, the display computer 45 and the autopilot computer 21 can form a single computer.

[0088] The display unit 45 may include one or more symbol generator units. For example, the display unit 45 may include a head-up symbol generator unit and a head-down symbol generator unit. Alternatively, the display unit 45 may include a single symbol generator unit. Each symbol generator unit may include, for example, at least one processor and at least one memory, at least one integrated circuit, at least one programmable system, at least one logic circuit, these examples not limiting the scope given to the expression "symbol generator unit." The term "processor" may refer to a central processing unit known by the acronym CPU, a graphics processing unit (GPU), a digital signal processor (DSP), a microcontroller, etc.

[0089] The display computer 45 can be connected directly or indirectly to the various sensors of the aircraft 1, and in particular to the aforementioned sensors 46-49.

[0090] Furthermore, the display computer 45 can be connected to a positioning device 44 determining information relating to the position or even the orientation of the head-up display 30, in the case of a head-up display 30 worn.

[0091] The positioning device 44 is connected to the display computer 45 by a wired or wireless link in order to transmit a signal, for example, analog or digital. This signal allows the display computer 45 to determine, using a known technique, where to position certain symbols. According to the illustrated example, the positioning device 44 thus includes at least one camera.

[0092] The examples given are provided for illustrative purposes only. The control system 40 and the autopilot system 20 may in fact be of another known type without departing from the scope of the claims.

[0093] Regardless of the embodiment of the head-up display 30, the control system 40, and the autopilot system 20, the control system 40 and the head-up display 30 are configured to apply the process schematically illustrated in [Fig. 3]. This process comprises one or more of the following steps carried out in a loop.

[0094] This method includes, for at least one PAR parameter, an STP0 detection with a control system 40 of a current mode applied by the control system to automatic 20. The current mode is in fact chosen by an operator 6 from among the predetermined operating modes of the automatic piloting system 20. For example, the human-machine selection interface 22 transmits a signal carrying the current mode to be applied to the control system 40, possibly to the display computer 45, directly or via the automatic piloting computer 21.

[0095] The method therefore includes the STP1, STP2, STP3 command of the head-up display 30 with the control system 40, and in particular with the display computer 45. The control system 40 then transmits a control signal to the head-up display 30 which varies according to the current mode applied for each PAR parameter. The control signal may include the symbols to be displayed. Upon receiving the control signal, the method then displays, for each PAR parameter, a symbol 50 on the head-up display 30 representing the current value of the PAR parameter according to a graphical style specific to the current mode.

[0096] Thus, when the operating mode of the autopilot system 20 is disengaged for a PAR parameter, the display control unit 45 executes the STP1 command to the head-up display 30 by transmitting a control signal to it. Upon receiving this control signal, the head-up display 30 displays an STP11 symbol bearing the current value of this PAR parameter according to a first graphic charter. The first graphic charter defines the appearance to be given to this symbol.

[0097] This symbol may include an object. This object may be a number equal to the current value, a scale and a cursor pointing to the scale, a value equal to the current value, for example, or a geometric shape. Therefore, the graphic charter may define, for example, the thickness of at least one line of an object, whether or not to add a frame, at least partially, around the object, what shape the object should have, etc.

[0098] When the operating mode of the autopilot system 20 is engaged for a PAR parameter, the display control unit 45 executes the STP2 command to the head-up display 30 by transmitting a control signal. Upon receiving this control signal, the head-up display 30 displays an STP21 symbol representing the current value of this PAR parameter according to a second graphical representation. The appearance of the symbol differs with the second graphical representation from the appearance obtained with the first graphical representation for the same PAR parameter value.

[0099] When the operating mode of the autopilot system 20 is armed for a PAR parameter, the display computer 45 executes the STP32 command to the head-up display 30 by transmitting a control signal to it. Upon receiving this control signal, the head-up display 30 displays STP31 is a symbol bearing the current value of this PAR parameter according to a third graphic charter. The third graphic charter defines the appearance to be given to this symbol, the appearance of the symbol being different from the appearance obtained with the first graphic charter and the second graphic charter for the same value of the PAR parameter.

[0100] Figures 4 and 5 illustrate the process of the invention with examples.

[0101] Figure 4 illustrates the display of symbols 50 associated with PAR parameters for which the autopilot system 20 is not engaged. Figure 5 illustrates the display of symbols 50 associated with these same PAR parameters but for which the autopilot system 20 is engaged. Reference numeral 50 designates any symbol, while reference numerals 51 to 54 designate specific symbols.

[0102] According to the example illustrated in [Fig.4], the head-up display 30 can present a symbol 51 bearing the current value of the indicated airspeed measured with the airspeed sensor 46, a symbol 52 bearing the current value of the altitude measured with the altitude sensor 47, a symbol 53 bearing the current value of the heading measured with the heading sensor 48 and a symbol 54 bearing the current flight direction vector displayed in conformity and measured with the flight direction vector sensor 49.

[0103] According to a first variant, a symbol 50 may include an object 60 according to the first graphic charter, and this same object 60 and a frame 61 surrounding it at least partially according to the second graphic charter.

[0104] According to [Fig. 4], this object 60 may include a number equal to the current value of the associated PAR parameter, or even letters forming the unit used, as illustrated by the symbol 51 bearing the current value of the indicated airspeed and by the symbol 52 bearing the current value of the altitude. An object 60 may alternatively include a scale 541 and a pointer 542, as illustrated by the symbol 54 bearing the current value of the heading.

[0105] Optionally, object 60 can be highlighted when applying the third graphical chart to indicate that the autopilot mode associated with the associated PAR parameter is the armed mode. Symbol 51, bearing the current indicated airspeed value, thus includes dashed lines below the corresponding object to illustrate this possibility.

[0106] With reference to [Fig. 5], when the autopilot system is engaged to control the aforementioned PAR parameters, a symbol 50 includes a frame 61 that at least partially surrounds the object 60. Thus, both symbols 51 and 52 have an object 60 completely enclosed by a rectangular frame 61, as in the example given, whereas symbol 54 has a frame 61 that partially surrounds its object. The frame 61 may, however, have a completely different shape, for example, a hexagonal shape.

[0107] According to a second variant and with reference to [Fig. 4], said symbol 53 may include a first object 63 according to the first graphic charter. Thus, the symbol 53 carrying the flight direction vector includes a first geometric shape comprising two segments 65, 66 on either side of a circle 67, the two segments 65, 66 being collinear.

[0108] On the other hand, and as illustrated in [Fig.5], this same symbol 53 may, according to the second graphic charter, include a second object 64 visually different from the first object 63.

[0109] For example, the first object 63 has a first geometric shape, the second object 64 has a second, different geometric shape. Thus, the symbol 53 carrying the flight direction vector now has a second geometric shape comprising two segments 65, 66 on either side not of a circle 67 but of a rhombus 68, the two segments 65, 66 being collinear.

[0110] For example, the first object 63 and the second object 64 may have at least one of the same stroke. Thus, the first object 63 and the second object 64 both include the segments 65, 66 according to the example of the symbol 53. However, the strokes 65, 66 have a first thickness epl in the first object 63 visible in [Fig.4] and a second thickness ep2 greater than the first thickness epl in the second object 64 visible in [Fig.5].

[0111] Regardless of the variant, the applied graphic charter does not affect the position of the symbol 50 on the head-up display 30. For the same current value of a PAR parameter, the associated symbol 50 is in the same position, namely in the same restricted area of ​​the head-up display 30, regardless of the applied graphic charter.

[0112] Furthermore, during a transitional phase of switching from an old mode to a new mode chosen from among the said possible operating modes of the autopilot system 20, for example to illustrate a switch from the disengaged mode to the engaged mode, the control system 40 can command the head-up display 30, to display on the head-up display 30 the relevant symbol 50, for a predetermined transitional period, alternately according to the graphic charter of the old mode and the graphic charter of the new mode.

[0113] According to another aspect of the invention and with reference to [Fig. 5], the control system 40 can be configured to perform an STP4 detection when the current value of a parameter differs from its setpoint value transmitted by the autopilot system 20. In this case, the method of the invention may include an STP41 command transmitted from the control system 40 to the head-up display 30 to request an STP42 display on the head-up display 30 of the setpoint value 85 opposite the relevant symbol 50. A segment 86 may Optionally, the setpoint value may extend from the setpoint value to the symbol 50. Optionally, the setpoint value is displayed for the operator's 7 to see above the symbol 50 when the setpoint value 85 is greater than the current value, and below the symbol 50 when the setpoint value 85 is less than the current value. In the illustrated example, a setpoint value 851 for the indicated airspeed is thus displayed above the symbol 51, and a setpoint value 852 for the altitude is displayed below the symbol 52.

[0114] Optionally, a distance D1, D2 separating the setpoint value and the associated symbol varies according to the result of a subtraction between the setpoint value and the current value of the parameter concerned. The same applies to the length of the segment that may be displayed.

[0115] Naturally, the present invention is subject to numerous variations in its implementation. Although several embodiments have been described, it is understood that it is not conceivable to exhaustively identify all possible embodiments. It is, of course, conceivable to replace a described means with an equivalent means without departing from the scope of the present invention and the claims.

Claims

Demands

1. A method for piloting an aircraft (1) comprising a head-up display (30) and an autopilot system (20), the autopilot system (20) comprising a selector human-machine interface (20) for choosing an operating mode from among several predetermined operating modes including a disengaged mode and an engaged mode in order to require autopilot control of at least one parameter, the autopilot system (20) being configured in the engaged mode to control at least one actuator (25) of the aircraft (1) in order to cause a current value of said parameter (PAR) to tend towards a setpoint value, the method comprising the following steps: - detection (STP0) with a control system (40) of a current mode applied from among said several predetermined operating modes, - control (STP1, STP2, STP3) of the head-up display (30) with the control system (40), and display (STP11,STP21 STP31) on the head-up display (30) of a symbol (50) bearing said current value, characterized in that said display (STP11, STP21 STP31) on the head-up display (30) of a symbol (50) bearing said current value is carried out according to a graphic charter specific to the current mode to visualize the current mode, a first graphic charter applied during the disengaged mode being different from a second graphic charter applied during the engaged mode.

2. Method according to claim 1, characterized in that, for the same current value, the symbol (50) is in the same position on the head-up display (30) regardless of the current mode.

3. A method according to any one of claims 1 to 2, characterized in that said symbol (50) comprises an object (60) according to the first graphic charter, said symbol (50) comprising said object (60) and a frame (61) surrounding at least partially the object (60) according to the second graphic charter.

4. A method according to any one of claims 1 to 3, characterized in that said symbol (50) comprises a first object (63) according to the first graphic charter, said symbol (50) comprising according to the second graphic charter a second object (64) visually different from the first object (63).

5. Method according to claim 4, characterized in that said first object (63) comprises a first geometric shape, the second object (64) comprising a second geometric shape, the second shape being visually different from the first shape.

6. A method according to any one of claims 4 to 5, characterized in that the first object (63) and the second object (64) have at least one of the same feature (65, 66), the feature (65, 66) having a first thickness (epl) in the first object (63), the feature (65, 66) having in the second object (64) a second thickness (ep2) greater than the first thickness (epl).

7. A method according to any one of claims 1 to 6, characterized in that said several modes of operation include an armed mode during which said setpoint value is parameterized, provided that the current mode is the armed mode, then said method includes a control (STP3) of the head-up display (30) with the control system (40) and a display (STP31) on the head-up display (30) of said symbol (50) according to a third graphic charter different from the first graphic charter and the second graphic charter.

8. A method according to any one of claims 1 to 7, characterized in that during a mode change to switch from an old mode to a new mode chosen from said several operating modes, said method comprises a control of the head-up display with the control system (40) and a display on the head-up display (30) of said symbol, for a predetermined transient duration, alternately according to the graphic charter of the old mode and the graphic charter of the new mode.

9. A method according to any one of claims 1 to 8, characterized in that said method comprises a detection (STP4) that the current value is different from the setpoint value, and provided that the current value is different from the setpoint value, the method comprises a control (STP41) of the head-up display (30) with the control system (40) and a display (STP42) on the head-up display (30) of the setpoint value opposite said symbol.

10. A method according to claim 9, characterized in that the setpoint value is displayed to an operator above the symbol when the setpoint value is greater than the current value and below the symbol when the setpoint value is less than the current value.

11. A method according to any one of claims 9 to 10, characterized in that a distance separating the setpoint value and the associated symbol varies according to a gap separating the setpoint value from the current value of the parameter concerned.

12. Aircraft (1) comprising a head-up display (30) and an autopilot system (20), the autopilot system (20) comprising a selector human-machine interface (20) for choosing an operating mode from among several predetermined modes comprising a disengaged mode and an engaged mode in order to require autopilot of at least one parameter, the autopilot system (20) being configured in the engaged mode to control at least one actuator (25) of the aircraft (1) in order to cause a current value of the piloted parameter to tend towards a setpoint value, said aircraft (1) comprising a control system (40) for controlling said head-up display (30), characterized in that the control system (40) and the head-up display (30) are configured to apply the method according to any one of claims 1 to 10.

13. Aircraft according to claim 11, characterized in that said head-up display (30) is monochrome.

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