EP4170627A1 - Method and system to assist with piloting an aircraft in flight - Google Patents

Abstract

The present invention relates to a method for aiding the piloting of an aircraft near an overflown zone. Said method comprises steps of determining an attitude and a height of said aircraft, of capturing an image of said zone overflown using a camera positioned under said aircraft, and of displaying on a display (15) of a representation (20) of said overflown zone covering an angular field of at least 220° in a vertical plane. Steps of calculating a first position (33) and a second position (113) on said representation (20) of vertical projections of reference points of said aircraft and of said camera on said overflown zone as a function of said attitude and of said height. Finally, steps of displaying a symbol (21) representing said aircraft and positioned on said first position (33), as well as a horizon circle (25) representing an artificial horizon line and centered on said second position (113) are made.

Description

The present invention is in the field of piloting aids for aircraft and rotorcraft in particular.

The present invention relates to a method for aiding the piloting of an aircraft in flight as well as a system for aiding the piloting of an aircraft in flight.

The aircraft may be a rotorcraft comprising at least one rotary wing, for example at least one lift rotor, allowing it in particular to perform stationary flights as well as forward flights at low speeds. An aircraft can also perform take-offs and landings on landing areas of reduced dimensions.

An aircraft can land on prepared landing areas. A prepared landing area can be located on the ground, on the roof of a building, as well as on a boat or a platform located at sea.

An aircraft can also land on unprepared landing areas located in an urban environment, and in fact potentially surrounded by buildings and/or street furniture in particular. An aircraft can also land on unprepared landing areas located in a natural environment and in this case potentially surrounded by vegetation and likely not to be perfectly flat, or even to include rocks.

Therefore, in order to help a pilot during the landing and take-off phases, the cockpit of an aircraft may comprise a transparent zone, for example glazed, at the level of the pilot's feet so as to allow him to see the ground. . However, the vision of the ground remains partial and the observable zone has dimensions which are reduced as the aircraft approaches the ground. Near of the landing area, the pilot may not be able to see the possible contact points for at least certain landing gears of the aircraft.

An aircraft may also include a landing point indication system as described in document EP 2708853 . This system comprises at least one camera and a screen displaying a view of the area located under the aircraft. This system also comprises a device for measuring an attitude of the aircraft. The screen displays an indication of the position projected on the ground of the aircraft, in particular according to its attitude.

Additionally, the document US 2012/0154178 describes a method for presenting information on the attitude and heading of an aircraft on a display, consisting, on the basis of data supplied by an inertial unit, of representing graphic elements in three dimensions on a two-dimensional display, and of presenting the attitude (roll, pitch, or even yaw) and heading information on the two-dimensional display by associating them with at least one spatial attitude graphic element indicating the attitude of the aircraft. For example, a fixed transparent sphere represents an inertial reference frame, two upper and lower half-spheres representing the sky and the ground respectively.

In this context, the present invention aims to overcome the limitations mentioned by providing assistance in piloting an aircraft by allowing the pilot to visualize, substantially in real time or near real time, the area located under the aircraft. as well as the position of the aircraft.

The subject of the present invention is therefore a method for aiding the piloting of an aircraft as well as a system for aiding the piloting of an aircraft.

• une structure,
• un dispositif de capture d'images,
• un premier dispositif de mesure pour déterminer une attitude de l'aéronef,
• un second dispositif de mesure pour déterminer une hauteur de l'aéronef par rapport à une zone survolée par l'aéronef,
• un dispositif de visualisation, et
• un calculateur.

First of all, the subject of the present invention is a method for aiding the piloting of an aircraft, the aircraft comprising:

• a structure,
• an image capture device,
• a first measuring device for determining an attitude of the aircraft,
• a second measuring device for determining a height of the aircraft relative to an area overflown by the aircraft,
• a display device, and
• a calculator.

• détermination d'une attitude de l'aéronef avec le premier dispositif de mesure,
• détermination d'une hauteur de l'aéronef par rapport à la zone survolée avec le second dispositif de mesure,
• capture d'au moins une image de la zone survolée par l'aéronef avec ledit dispositif de capture d'images,
• affichage sur le dispositif de visualisation d'une représentation de la zone survolée, cette représentation comprenant ladite au moins une image,
• calcul par le calculateur d'une première position sur la représentation de la zone survolée d'une projection verticale sur la zone survolée d'un premier point de référence de l'aéronef en fonction de l'attitude et de la hauteur de l'aéronef,
• calcul par le calculateur d'une seconde position sur la représentation d'une projection verticale sur la zone survolée d'un second point de référence du dispositif de capture d'images en fonction de l'attitude,
• affichage sur le dispositif de visualisation d'un symbole représentant l'aéronef, un point d'origine du symbole étant positionné sur la première position, et
• affichage sur le dispositif de visualisation d'un cercle d'horizon représentant une ligne d'horizon, le cercle d'horizon étant centré sur la seconde position, un diamètre du cercle d'horizon étant constant.

This process is remarkable in that it comprises the following steps:

• determination of an attitude of the aircraft with the first measuring device,
• determination of a height of the aircraft relative to the area overflown with the second measuring device,
• capture of at least one image of the area overflown by the aircraft with said image capture device,
• display on the display device of a representation of the zone overflown, this representation comprising said at least one image,
• calculation by the computer of a first position on the representation of the overflown zone of a vertical projection on the overflown zone of a first reference point of the aircraft as a function of the attitude and the height of the aircraft ,
• calculation by the computer of a second position on the representation of a vertical projection on the overflown zone of a second reference point of the image capture device as a function of the attitude,
• display on the display device of a symbol representing the aircraft, an origin point of the symbol being positioned on the first position, and
• display on the display device of a horizon circle representing a horizon line, the horizon circle being centered on the second position, a diameter of the horizon circle being constant.

The structure of the aircraft comprises for example a cell, or even a tail boom and/or wings. A pilot and possibly other occupants are installed in the cell during the flight of the aircraft.

The horizon circle represents the projection of the horizon line around the aircraft. The diameter of the horizon circle is constant, ie independent of the height and attitude of the aircraft. The value of the diameter of the horizon circle is predetermined, in particular according to the dimensions of the display device as well as the dimensions of the representation and/or the optical characteristics of the capture device.

The first position and the second position which correspond respectively to vertical projections on the overflown zone of a first reference point of the aircraft and of a second reference point of the image capture device move on the representation during aircraft attitude changes.

In fact, the symbol illustrating the footprint of the aircraft on the zone overflown moves on the representation during the attitude changes of the aircraft.

The second position can advantageously be calculated without using the height of the aircraft, although this position is a function of this height. This second position is the position of a vertical projection on the overflown zone of a second reference point of the image capture device. Consequently, this second position can be determined with respect to the center of the image captured by the image capture device as a function of a parameter of the image capture device and of the attitude of the aircraft. This parameter is for example the focal length of the lens of the image capture device, this focal length being in this case fixed. This parameter can also be an equivalent focal length when the representation of the overflown zone is formed from several images.

Alternatively, this second position can be calculated as a function of the attitude and the height of the aircraft.

Similarly, the horizon circle which is always centered on the second position also moves on the representation during changes in attitude of the aircraft. Consequently, and depending on the attitude of the aircraft, the horizon circle may only be displayed partially on the representation, for example when the aircraft has a pitch-up angle and/or a large roll angle . The horizon circle thus enables the pilot of the aircraft to visualize on the representation the changes in attitude of the aircraft as well as the obstacles located at height, in particular above the horizon circle.

Thanks to the display of the projected position of the aircraft on the area overflown and of the horizon circle on the display device superimposed on the representation of the area overflown, the pilot can locate the aircraft with respect to the area overflown , and in particular in relation to the landing area and any obstacles or objects located on or near the landing area.

The pilot can then make a safe landing on any type of landing area, prepared or not.

The image capture device is directed towards the ground and makes it possible to capture images of the area overflown by the aircraft when the aircraft is in flight. The image capture device can be attached to the cell or to the tail boom, or even to a wing.

The zone overflown can be for example the terrestrial ground, the roof of a building, a boat or even a platform located at sea.

The height of the aircraft relative to the area overflown is equal to the shortest distance between the aircraft and the area overflown, this height being defined parallel to the direction of the earth's gravity. The height of the aircraft can be defined for example with respect to a predetermined point of the aircraft.

The attitude of the aircraft characterizes the attitude of the aircraft, namely its roll angle and its pitch angle around respectively a roll axis and a pitch axis of the aircraft. The aircraft has a zero attitude when its roll angle and its pitch angle are simultaneously equal to zero. The roll and pitch axes of the aircraft are then parallel to a horizontal plane defined perpendicular to the direction of the earth's gravity.

The method according to the invention may further comprise one or more of the characteristics which follow, taken alone or in combination.

According to one example, the representation of the area overflown covers an angular field of 360° in a horizontal plane and of at least 180° in a vertical plane when the attitude of the aircraft is zero, the vertical plane being parallel to a direction of earth's gravity and the horizontal plane being perpendicular to the direction of earth's gravity. In this way, the pilot has an overview of the area overflown in order to apprehend all the obstacles likely to be in the area overflown, in particular the obstacles in height protruding from the horizon circle. Preferably, the representation of the overflown zone covers an angular field of 360° in a horizontal plane and of at least 220° in a vertical plane when the attitude of the aircraft is zero.

This representation of the area overflown is sufficient to allow the pilot of the aircraft to become aware of the environment of the landing area and then to perform a landing maneuver in complete safety. In addition, in this case, the representation of the area overflown allows the pilot to have an idea of the attitude of the aircraft, in particular thanks to the relative movements of the sky on the representation of the area overflown and the position of the circle of horizon which can be offset on the representation of the area flown over.

According to another example compatible with the previous ones, the image capture device can comprise at least a single camera or a single photographic device.

According to a first variant, the image capture device may comprise a single camera or a single photographic device fixed relative to the structure of the aircraft and provided with a lens covering an angular field of 360° in a plane perpendicular to an optical axis of the camera or photographic device and a field of at least 180° in a plane parallel to this optical axis. This optical axis is for example parallel to a direction of terrestrial gravity when the aircraft has a zero attitude. The second reference point of the image capture device is then the center of this lens. The representation of the overflown zone then corresponds exactly to the image captured by the image capture device.

For this purpose, the camera or photographic device may comprise a “fish-eye” type lens. Such a goal entails by its construction a deformation of the captured image according to an equidistant or equisolid projection for example.

According to a second variant, the image capture device may comprise a single camera or a single mobile camera relative to the structure of the aircraft in order to cover an angular field of 360° in a horizontal plane and a field of at least 180° in a vertical plane.

According to a third variant, the image capture device may comprise several cameras or several still cameras fixed relative to the structure of the aircraft and jointly covering an angular field of 360° in a horizontal plane and a field of at least 180° in a vertical plane.

For the second and third variants, the representation of the overflown zone is then constructed by the computer from the images provided by the image capture device. The representation of the overflown zone can have an equidistant or equisolid projection for example.

According to another example compatible with the previous ones, the symbol can be represented on the display device with variable dimensions depending on the height. In this way, the dimensions of the symbol can be representative of the dimensions of the vertical projection of the aircraft on the overflown zone, being variable as a function of the height of the aircraft.

The method can in this case comprise an additional step of calculation by the computer of the dimensions of the symbol at least as a function of the height of the aircraft. This additional calculation step optionally uses the dimensions of the aircraft and the height of the aircraft to calculate the dimensions of the symbol.

The symbol can also be represented on the display device with constant dimensions when the height is greater than a first predetermined threshold and the symbol can be represented on the display device with variable dimensions, possibly representative of the dimensions of the vertical projection of the aircraft over the area overflown, at least as a function of the height when the height is less than or equal to the first threshold. The dimensions of the symbol allow the pilot to assess the height of the aircraft. The first threshold is for example equal to 150 feet (150fts), one foot being equal to 0.3048 meter.

In this case, the method can also include the additional step of calculating the dimensions of the symbol, this step being applied when the dimensions of the symbol are variable as a function of the height.

Moreover, to avoid an untimely change in the management of the dimensions of the symbol around a height equal to the first threshold, a hysteresis threshold can be used. The first threshold then comprises a first high threshold and a first low threshold. The symbol is represented with constant dimensions when the height is greater than the first high threshold and the symbol is represented with variable dimensions when the height is less than or equal to the first low threshold. When the height decreases from a value greater than the first high threshold and remains greater than the first low threshold, the symbol is represented with constant dimensions. Conversely, when the height increases from a value below the first low threshold and remains below the first high threshold, the symbol is represented with variable dimensions.

A hysteresis value of the first threshold is equal to the difference between the first high threshold and the first low threshold, and is for example equal to 20 feet.

According to another example compatible with the previous ones, the symbol can be represented on the display device with different shapes when said height is greater than a first predetermined threshold and when said height is less than or equal to said first threshold. In this way, such a change in shape of the symbol can indicate to the pilot of the rotorcraft that the aircraft is at a height less than or equal to the first threshold and is therefore approaching the area overflown. In this case, a first threshold can also be a hysteresis threshold as previously mentioned.

The method can also simultaneously associate a change in shape of the symbol and a variation in the dimensions of the symbol with the passing of the first threshold. A first symbol can thus be represented on the display device with constant dimensions when the height is greater than the first predetermined threshold and a second symbol, different from the first symbol, can be represented on the display device with variable dimensions depending on the height of the aircraft when the height is less than or equal to the first threshold.

Furthermore, the symbol can be represented on the display device with constant dimensions independently of the height of the aircraft. In this way, whatever the height of the aircraft, the symbol of the aircraft is displayed with the same dimensions.

According to another example compatible with the previous ones, the aircraft can comprise at least one lift rotor, arranged for example above the structure, and the symbol then comprises a shape representing the structure and at least one rotor circle corresponding to the lift rotor. The method then comprises the additional step of calculating the dimensions of the symbol and during this additional step of calculation, the dimensional characteristics of said at least one rotor circle and the dimensional characteristics of the shape representing the structure are calculated as a function respectively of the diameter of said at least one lift rotor and the dimensions of the structure as well as the height of the aircraft. This additional calculation step makes it possible in particular to transfer said minus one rotor circle and the shape representing the structure of a reference linked to the aircraft to a reference linked to the image capture device

According to another example compatible with the previous ones, the aircraft comprising at least one lift rotor, the first reference point of the aircraft can be a center of rotation of one lift rotor among said at least one lift rotor.

According to another example compatible with the previous ones, the first measuring device can comprise for example at least one inertial unit or a device known by the acronym AHRS for the designation in English language "Attitude and Heading Reference System", at least one inclinometer or others, in order to determine or measure the attitude of the aircraft, namely its angles of roll and pitch.

According to another example compatible with the previous ones, the second measuring device can make it possible to directly measure the height of the aircraft relative to the area overflown and can comprise for this purpose a radiosonde for example. The step of determining a height of the aircraft relative to the area overflown thus comprises a measurement of this height by the second measuring device.

The second measuring device may alternatively comprise a barometric altimeter making it possible to measure a current atmospheric pressure, which is then compared with an atmospheric pressure at the altitude of the area overflown in order to calculate the height of the aircraft with respect to the area overflown .

The second measuring device may alternatively comprise at least one receiver of a satellite positioning system. The receiver provides a position of the aircraft in a terrestrial reference, for example in the form of latitude, longitude and altitude coordinates with respect to a reference level, generally sea level. This position of the aircraft in the The terrestrial landmark is then combined with a model of the terrain in stored three dimensions or else with the information from a stored terrain database in order to determine the height of the aircraft with respect to the zone overflown.

The three-dimensional modeling of the terrain can come from a terrain database stored in a memory.

The step of determining a height of the aircraft relative to the area overflown can alternatively use the focal length of an objective of the image capture device, thanks to an adapted processing of the value of the focal length.

According to another example compatible with the previous ones, the method can comprise a step of displaying on the display device a security circle around the symbol. This safety circle represents a safety bubble around the aircraft which must be respected, for example during a landing, no obstacle must interfere with the safety bubble and therefore interfere with the safety circle on the representation of the overflown area.

The safety circle can be centered on an intersection of the diagonals of a rectangle in which the symbol is inscribed.

The safety circle can have a variable diameter depending on the height. In this way, the diameter of the safety circle displayed on the representation can be representative of the real diameter of the safety bubble to be observed around the aircraft.

The step of displaying the safety circle may in this case comprise a calculation sub-step by the computer to calculate the diameter of the safety circle as a function of the height of the aircraft and a diameter of a rotor lift of the aircraft.

The diameter of the safety bubble is for example equal to twice the diameter of the lift rotor of the aircraft. When the symbol includes a shape representing the structure of the aircraft and at least one rotor circle and the dimensions of the symbol are also variable according to the height of the aircraft, the diameter of the safety circle is then equal to twice the diameter of the rotor circle.

The safety circle can be represented on the display device only when the height is less than or equal to the second threshold. In this way, when the safety circle is displayed, the pilot knows that the aircraft is approaching the overflown zone and visualizes the information on the dimensions of the vertical projection of the safety bubble on the overflown zone. The second threshold is for example equal to 300 feet (300 ft).

According to another example compatible with the previous ones, the method can comprise a step of displaying on the device for displaying marks of the cardinal points, namely the directions of North, South, East and West. These markers are for example displayed close to the horizon circle.

According to another example compatible with the previous ones, the method can comprise a step of displaying on the display device a heading indicator of the aircraft. The heading of the aircraft is aligned with the direction of the roll axis of the aircraft and represented on the representation of the area overflown in front of the aircraft. The heading indicator of the aircraft is for example displayed close to the horizon circle.

According to another example compatible with the previous ones, the method can comprise a step of displaying on the display device an indicator of the wind experienced by the aircraft. This wind indicator carries wind speed and/or wind direction information, for example supplied by an anemometer or a weather vane of the aircraft.

The present invention also relates to a system for aiding the piloting of an aircraft in flight. The aircraft comprises a structure provided for example with a cell and optionally with a tail boom and/or wings, and at least one lift rotor arranged for example above the cell.

• un dispositif de capture d'images,
• un premier dispositif de mesure pour déterminer une attitude de l'aéronef,
• un second dispositif de mesure pour déterminer une hauteur de l'aéronef par rapport à la zone survolée,
• un dispositif de visualisation, et
• un calculateur.

The piloting assistance system of an aircraft in flight comprises:

• an image capture device,
• a first measuring device for determining an attitude of the aircraft,
• a second measuring device for determining a height of the aircraft relative to the area overflown,
• a display device, and
• a calculator.

This system according to the invention is thus configured for the implementation of the method for aiding the piloting of an aircraft in flight previously described. This system can be installed on an aircraft at the time of its manufacture or else be added to an aircraft already in service in order to improve its safety and allow the pilot to easily and completely visualize a landing area and its environment.

The image capture device may include at least one camera or at least one photographic device. For example, the image capture device may comprise a single camera or at least a single photographic device fitted with a lens covering an angular field of 360° in a plane perpendicular to an optical axis of the camera or of the device photographic and of at least 180° in a vertical plane parallel to this optical axis. The second reference point of the image capture device is the center of the lens.

• la figure 1, un aéronef muni d'un système d'aide au pilotage d'un aéronef selon l'invention,
• la figure 2, un schéma synoptique d'un procédé d'aide au pilotage d'un aéronef selon l'invention,
• la figure 3, une vue de l'aéronef et de la zone survolée,
• la figure4, des images de la représentation de la zone survolée sur un dispositif de visualisation de l'aéronef,
• la figure 5, des images de la représentation de la zone survolée sur un dispositif de visualisation de l'aéronef, et
• la figure 6, des images de la représentation de la zone survolée sur un dispositif de visualisation de l'aéronef.

The invention and its advantages will appear in more detail in the context of the description which follows with exemplary embodiments given by way of illustration with reference to the appended figures which represent:

• there figure 1 , an aircraft fitted with an aircraft piloting aid system according to the invention,
• there picture 2 , a block diagram of a method for aiding the piloting of an aircraft according to the invention,
• there picture 3 , a view of the aircraft and the area overflown,
• there figure4 , images of the representation of the area overflown on a display device of the aircraft,
• there figure 5 , images of the representation of the area overflown on a display device of the aircraft, and
• there figure 6 , images of the representation of the area overflown on a display device of the aircraft.

The elements present in several separate figures are assigned a single reference.

There figure 1 represents a rotary-wing aircraft 1 fitted with a system 10 for aiding the piloting of the aircraft 1 in flight. The aircraft 1 comprises for example a structure 2. The structure 2 can be provided with a cell 4 and a tail boom 5 as well as at least one lift rotor 3 arranged for example above the cell 4 Other configurations of aircraft 1 can be envisaged in the context of the present invention, the structure 2 being able for example to comprise wings.

The system 10 comprises an image capture device 11 carried by the structure 2 and directed towards the ground, a first measuring device 16 for determining an attitude of the aircraft 1, a second measuring device 17 for determining a height of the aircraft 1 with respect to the area overflown, a display device 15 and a computer 13.

According to the example of figure 1 , the image capture device 11 is positioned vertically to a center of rotation 35 of the lift rotor 3 when the aircraft 1 has a zero attitude, a vertical direction being parallel to the direction of the earth's gravity. But the capture device 11 can alternatively be positioned in another position under, or even in the cell 4, or under or in the tail boom 5, or even under or in the wings of the structure 2. The display device 15 is positioned in cell 4 in a location visible to a pilot of aircraft 1.

The display device 15 may comprise a screen. The display device 15 can alternatively comprise part of the windshield of the aircraft 1 or even a digital tablet on board the aircraft 1, or even any other display means.

The aircraft 1 may also include an anemometer 18 or a weather vane in order to determine a direction and/or a speed of the wind experienced by the aircraft 1.

The computer 13 may comprise one or more processing units each having for example at least one processor and at least one memory 12, at least one integrated circuit, at least one programmable system, at least one logic circuit, these examples not limiting the scope given to calculator expression. The term processor can designate both a central processing unit known by the acronym CPU, a graphics processing unit GPU, a digital unit known by the acronym DSP, a microcontroller, etc. The computer 13 communicates, by a wired connection or a wireless link, with the first and second measurement devices 16,17, the image capture device 11, the memory 12 and the display device 15 as well as possibly with the anemometer 18 or the wind vane.

The piloting aid system 10 of the aircraft 1 in flight can also comprise a memory 19, communicating with the computer 13.

The system 10 for aiding the piloting of the aircraft 1 in flight is configured to implement a method for aiding the piloting of the aircraft 1 in flight, a synoptic diagram of which is represented on the picture 2 . A memory 12,19 may comprise a code or a segment of code applied by the computer 13 for carrying out this process. This method comprises the following steps.

First of all, a determination step 110 to determine an attitude of the aircraft 1 is carried out using the first measuring device 16. For this purpose, the first measuring device 16 can comprise at least one inertial unit or an AHRS device. The first measuring device 16 then transmits a signal, for example analog or digital, electrical or optical, to the computer 13, this signal carrying information relating to the attitude of the aircraft 1.

The attitude of the aircraft 1 is defined by a roll angle and a pitch angle of the aircraft 1 around respectively a roll axis and a pitch axis of the aircraft 1.

The method includes a determination step 120 for determining a height of the aircraft 1 relative to the overflown area is carried out using the second measuring device 17, this height being equal to the distance between the aircraft 1 and the overflown area defined parallel to the direction of Earth's gravity. The second measuring device 17 then transmits a signal, for example analog or digital, electrical or optical, to the computer 13, this signal carrying information relating to the height of the aircraft 1.

For this purpose, the second measuring device 17 may for example comprise a radiosonde directly measuring this height of the aircraft 1 relative to the area overflown, in a vertical direction, parallel to the direction of the Earth's gravity.

According to another example, the second measuring device 17 can comprise a barometric altimeter making it possible to measure a current atmospheric pressure. The determination step 120 can then include a sub-step 123 of measuring a current atmospheric pressure around the aircraft 1 carried out using the barometric altimeter. Next, a calculation sub-step 124 is carried out by the computer 13 or a processing unit of the second measuring device 17 in order to determine the height of the aircraft 1 by comparing the current atmospheric pressure with an atmospheric pressure at the altitude of the area overflown, this atmospheric pressure at the altitude of the area overflown having been previously stored in a memory of the aircraft 1, by example following a setting using an interface of the aircraft 1.

According to another example, the second measuring device 17 can comprise a receiver of a satellite positioning system. The determination step 120 can then comprise a determination sub-step 125 for determining a position of the aircraft 1 in a terrestrial reference produced using the receiver of the satellite positioning system. Next, a calculation sub-step 126 for calculating the height of the aircraft 1 relative to the area overflown is carried out by the computer 13 or another processing unit using the position of the aircraft 1 in the landmark and a three-dimensional terrain model or a stored terrain database.

The modeling of the three-dimensional terrain or the terrain database can be stored in the memory 12,19 or in an additional memory integrated, for example, into the system 10 or into the second measuring device 17.

According to another example, the determination step 120 can use the focal length of a lens of the camera or of the photographic device of the image capture device 11 to determine the height of the aircraft 1 with respect to the zone overflown, using for example a treatment adapted to this focal length.

The method includes a capture step 130 to capture at least one image of the overflown area is also using the image capture device 11. The image capture device 11 then transmits a signal, for example analog or digital, electrical or optical, to the computer 13, this signal carrying information relating to at least one captured image of the area flown over.

For this purpose, the image capture device 11 may comprise a single camera or a single still camera fixed with respect to the structure 2, as shown in the figure 1 . For example, the image capture device 11 covers an angular field of 360° in a horizontal plane and an angular field of at least 180° in a vertical plane.

The image capture device 11 can alternatively comprise a single camera or a single mobile camera with respect to the structure 2. The camera or the camera then moves according to a rotational movement with respect to a support fixed to the structure 2, for example in order to cover an angular field of 360° in a horizontal plane and an angular field of at least 180° in a vertical plane.

The image capture device 11 may alternatively comprise several cameras or several still cameras fixed relative to the structure 2 and jointly covering, for example, an angular field of 360° in a horizontal plane and an angular field of at least 180° in a vertical plane.

The determination steps 110, 120 and 130 can be carried out sequentially as shown or else in parallel, namely substantially simultaneously.

The method includes a display step 140 for displaying on the display device 15 a representation 20, as illustrated in figures 4 to 6 of the area overflown. The computer 13 then transmits a signal, for example analog or digital, electrical or optical, to the display device 15 to display the representation 20, this signal carrying information relating to the representation 20.

The representation 20 of the overflown zone covers for example an angular field of 360° in a horizontal plane and of at least 180° in a vertical plane when the attitude of the aircraft 1 is zero, the vertical plane being parallel to a direction of earth's gravity and the horizontal plane being perpendicular to the direction of earth's gravity. According to the examples shown on the figures 4 to 6 , the representation 20 covers an angular field of 360° in a horizontal plane and of at least 220° in a vertical plane when the attitude of the aircraft 1 is zero.

The representation 20 is formed by each image captured successively by the image capture device 11 when it comprises a single camera or a single fixed camera with respect to the structure 2.

When the image capture device 11 comprises either a single camera or a single mobile camera with respect to the structure 2, or several cameras or several fixed cameras with respect to the structure 2, the computer 13 then constructs the representation 20 from the images captured by the camera(s) or the camera(s) and transmitted to the computer 13, so as to form a single image of the area overflown covering the required angular field. The display step 140 then includes an additional step 145 of construction of the representation 20 from the images captured by the camera(s) or the camera(s), this additional step of construction 145 being carried out for example by the computer 13 or another processing unit.

This representation 20 allows a pilot of the aircraft 1 to have a complete view of the overflown zone located under the aircraft 1.

The method includes a calculation step 150 for calculating a first position 33 on the representation 20 of a vertical projection on the overflown zone of a first reference point 31 of the aircraft 1 produced using the computer 13, by function of the attitude of the aircraft 1 and of the height of the aircraft 1 relative to the area overflown. The vertical projection of the first reference point 31 onto the overflown zone is carried out parallel to the direction of the earth's gravity. For this purpose, after having received the information relating to the attitude and height of the aircraft 1, and knowing the relative positions of the first and second reference points 31,111, the computer 13 determines the first position 33 on the representation 20 using a memorized law, a table of values or others. Optionally, the computer 13 stores this first position 33 in a memory 12.19. The computer 13 can thus determine and store the first successive positions 33 during a flight of the aircraft 1.

The method includes a calculation step 160 for calculating a second position 113 on the representation 20 of a vertical projection on the zone flown over by a second reference point 111 of the image capture device 11 produced using the computer 13, depending on the attitude of the aircraft 1. The vertical projection of the second reference point 111 on the overflown zone is carried out parallel to the direction of the earth's gravity. For this purpose, after having received the information relating to the attitude, the computer 13 determines, using a memorized law, a table of values or others, the second position 113 on the representation 20, and optionally stores this second position 113 in a memory 12.19. The computer 13 can thus determine and store the second successive positions 113 during a flight of the aircraft 1.

The memorized law or the table of values can for example involve a parameter of the image capturing device 11 such as the focal length of the objective of the image capturing device. The distance between the second position and the center of an image captured by the image capture device 11 is for example equal to the product of a coefficient function of this parameter of the image capture device multiplied by the angle of attitude of the aircraft in the case of an equidistant projection. This distance is for example equal to the product of a coefficient function of this parameter of the image capture device multiplied by the sine of the attitude angle of the aircraft in the case of an equisolid projection.

The first reference point 31 and the second reference point 111 are specific points respectively of the aircraft 1 and of the image capture device 11. The reference point 31 is for example a center of rotation 35 of the lift rotor 3 of the aircraft 1 and the second reference point 111 is for example the center of the lens of the camera or of the photographic device of the image capture device 11 as represented on the picture 3 ,.

There picture 3 represents the first and second positions 33,113 defined by vertical projection of the first and second reference points 31, 111 on the representation 20.

Then, a display step 170 to display on the display device 15 a symbol 21 representing the aircraft 1 is carried out, an origin point of the symbol 21 being positioned on the first position 31. The computer 13 then transmits a signal , for example analog or digital, electrical or optical, to the display device 15 to display the symbol 21, this signal carrying information relating to the symbol 21 and to the first position 33. The figures 4 to 6 represent the display of the symbol 21 positioned on the first position 33 on the device display 15 superimposed on the representation 20 of the area flown over.

Thus, the pilot of the aircraft 1 can visualize the symbol 21 on the representation 20 and, consequently, on the zone overflown in order in particular to anticipate and prepare a landing by having a vision of the aircraft with respect to the zone overflown, to a potential landing zone and to possible obstacles.

The symbol 21 can be represented on the display device 15 with constant dimensions independently of the height of the aircraft 1.

The symbol 21 can alternatively be represented on the display device 15 with variable dimensions depending on this height of the aircraft 1. The method then includes an additional calculation step 165 for calculating, using the computer 13 and d a memorized law, of a table of values or others, the dimensions of the symbol 21 according to the height of the aircraft 1. The dimensions of the symbol 21 can for example correspond, on the representation 20 to the dimensions of the vertical projection of the aircraft 1 on the overflown zone. The computer 13 then transmits to the display device 15 a signal, for example analog or digital, electrical or optical, carrying information relating to the dimensions of the symbol 21.

In this case, the additional calculation step 165 takes into account the scale used for the display of the zone overflown on the representation 20. This scale can for example be a function of a focal length of the camera(s) or photographic devices of the image capture device 11 and possibly of a coefficient applied by the computer 13 for the display of the representation 20 on the display device 15.

The symbol 21 can take various forms, such as a cross, a circle. The point of origin of symbol 21 can for example be the center of symbol 21.

The symbol 21 can alternatively take the form of an aircraft seen from above and include in particular a rotor circle 213 representing the lift rotor 3 and a shape 212 representing the structure 2 as represented on the figure 5 And 6 . The point of origin of symbol 21 can in this case be the center of rotor circle 213.

During the additional calculation step 165, the computer 13 determines the dimensions of the symbol 21, for example the dimensional characteristics of the rotor circle 213 and of the shape 212 using a memorized law, a table of values or others depending respectively on a diameter of the lift rotor 3 and the dimensions of the structure 2 as well as the height of the aircraft 1. The computer 13 then transmits to the display device 15 a signal, for example analog or digital, electrical or optical, carrying information relating to the dimensions of the symbol 21.

The symbol 21 can alternatively be represented on the display device 15 with constant dimensions when the height of the aircraft 1 is greater than this first threshold and the symbol 21 can be represented on the display device 15 with variable dimensions depending on of this height, as previously mentioned, when the height is less than or equal to the first threshold. For this purpose, the computer 13 compares the height with the first threshold. Therefore, if the height is greater than this first threshold, the computer 13 transmits to the display device 15 a signal carrying information relating to constant dimensions of the symbol 21 and to the first position 31 and if when the height is lower or equal at the first threshold, the computer 13 calculates the dimensions of the symbol 21 as a function in particular of this height and transmits to the display device 15 a signal carrying information relating to these dimensions of the symbol 21 and to the first position 31.

The additional calculation step 165 is therefore performed as a function of the height of the aircraft 1 and of the first threshold, namely when the height is less than or equal to the first threshold. Consequently, the symbol 21 representative of the dimensions of the vertical projection of the aircraft 1 on the area overflown when the aircraft 1 is displayed when the aircraft 1 is located close to the area overflown, namely at a lower height or equal to the first threshold, in order to help the pilot during these maneuvers.

Moreover, the first threshold can be a hysteresis threshold and as such comprise a first low threshold and a first high threshold. The symbol 21 is then represented with constant dimensions when the height is greater than the first high threshold and the symbol 21 is represented with variable dimensions when the height is less than or equal to the first low threshold. Moreover, when the height is situated between the first high threshold and the first low threshold, the way of displaying the symbol, namely with constant or variable dimensions, is not modified.

Furthermore, the method includes a display step 180 for displaying on the display device 15 a horizon circle 25 representing a horizon line. The horizon circle 25 represents the projection of the horizon line around the aircraft 1. The horizon circle 25 is displayed with a constant diameter value, independent of the height and attitude of the aircraft 1. The horizon circle 25 is always centered on the second position 113. The second position 113 can therefore move on the representation 20 when the attitude of the aircraft 1 varies and the circle horizon 25 may then not appear entirely on the representation 20, in particular when the roll angle and/or the pitch angle of the aircraft 1 is significant. For this purpose, the computer 13 transmits to the display device 15 a signal, for example analog or digital, electrical or optical, carrying information relating to the dimensions of the horizon circle 25 and to the second position 113.

According to the aircraft example 1 represented on the figure 1 , the image capture device 11 comprises a single camera positioned vertically to the center of rotation 35 of the lift rotor 3 when the aircraft 1 has a zero attitude, its roll and pitch angles being equal to zero. An optical axis 117 of the image capture device 11 is vertical when the aircraft 1 has a zero attitude. The first reference point 31 and the second reference point 111 are in fact located on this optical axis 117. Consequently, the first position 33 and the second position 113 are displayed coincident and positioned at the center of the representation 20 when the aircraft 1 has a null attitude as represented on the figure 3 And 4 . In this case, the horizon circle 25 and the symbol 21 are in the first position 33 and the second position 113 and therefore positioned at the center of the representation 20.

On the figure 6 , the first position 33 and the second position 113 are distinct and the horizon circle 25 is offset with respect to the representation 20. Such a configuration may be the consequence of the use of an image capture device 11 comprising for example a single camera offset longitudinally from the vertical of the center of rotation 35 of the lift rotor 3. Such a camera can for example be positioned under the tail boom 5 according to the example of aircraft 1 represented on the picture 3 .

This can alternatively be the consequence of a non-zero attitude of the aircraft 1. In the case of the figure 6 , these two possible reasons are combined. It can in fact be seen that the aircraft 1 has a non-zero attitude, the distribution of the sky around the ground on the representation 20 not being uniform.

Thanks to the method according to the invention, the pilot of the aircraft 1 can visualize on the representation 20 the projection of the horizon line around the aircraft 1 in order to facilitate his vision of the zone overflown and of the potential area of landing as well as obstacles, in particular obstacles at height located above the horizon circle 25. The pilot of the aircraft 1 can also, thanks to the position of the horizon circle 25 and its possible movements on the representation 20 have a view of the attitude changes of the aircraft 1.

For a representation 20 covering an angular field of 220° in a vertical plane and produced with an equidistant projection, the horizon circle 25 is for example displayed on a display device 15 having dimensions of 150mm×150mm with a diameter equal to 123mm.

Furthermore, the method may include a display step 190 to display on the display device 15 a safety circle 26 around the symbol 21. The safety circle 26 is for example centered on an intersection 263 of the diagonals of a rectangle 265 in which the symbol 21 is inscribed. The computer 13 then transmits to the display device 15 a signal carrying information, for example analog or digital, electrical or optical, relating to the dimensions of the safety circle 26 and to its position around the symbol 21.

This safety circle 26 allows the pilot to visualize a safety bubble around the aircraft 1 in which no obstacle the area flown over must only be located in order to achieve, for example, a safe landing.

The safety circle 26 can be displayed on the representation 20 only when the height of the aircraft 1 is less than or equal to a second threshold. The pilot thus knows when the safety circle 26 is displayed that he has reached a height less than or equal to the second threshold. For this purpose, the computer 13 compares the height with the second threshold. Consequently, if the height is greater than this second threshold, the computer 13 does not transmit to the display device 15 any signal relating to the safety circle 26 and if the height is less than or equal to the second threshold, the computer 13 transmits to the visualization 15 of a signal carrying information relating to the safety circle 26 and its position.

The diameter of the safety circle 26 can also be variable depending on this height. The display step 190 of the safety circle 26 then includes a calculation sub-step 195 for calculating, using the computer 13, the diameter of the safety circle 26 as a function of the height of the aircraft 1 and of a diameter of a lift rotor 3. The computer 13 then calculates the dimensions of the safety circle 26 as a function in particular of this height and the diameter of a lift rotor 3, then transmits to the display device 15 a signal carrying information relating to these dimensions of the safety circle 26 and its position.

The method can also include a display step 200 for displaying on the display device 15 markers 27 of the cardinal points. These markers 27 are for example lines attached to the horizon circle 25 respectively indicating the directions of North, South, East and West as indicated on the figures 4 to 6 .

The positions of these markers are for example determined using the first measuring device 16 comprising for example at least one inertial unit or an AHRS device. The computer 13 receives from the first or from the second measuring device 16,17 a signal carrying information relating to the directions of the cardinal points, then transmits to the display device 15 a signal carrying information relating to the positions of the markers 27 on the representation 20.

The positions of these marks can also be determined according to another example using another measuring device, such as a compass or a compass determining the direction of magnetic North. The computer 13 receives a signal carrying information relating to this direction of magnetic North and adds thereto the magnetic declination relating to the position of the aircraft 1 in order to determine the direction of geographic North and to deduce therefrom the positions of the other cardinal points.

The values of the magnetic variations relating to the different positions of the aircraft 1 are for example stored in a memory 12,19. The computer 13 can then transmit to the display device 15 a signal carrying information relating to the positions of the markers 27 on the representation 20. The magnetic declination relating to the position of the aircraft 1 can also be determined using the second measuring device 17 comprising for example a receiver of a satellite positioning system which determines an absolute position of the aircraft 1 from which the magnetic declination can be deduced.

The method can also include a display step 210 for displaying on the display device 15 a heading indicator 28 of the aircraft 1. The heading indicator 28 is for example a line attached to the horizon circle 25, towards the front of the aircraft 1 and aligned with the direction of the roll axis of the aircraft 1. complementary indicators 29 can also be attached to the horizon circle 25 respectively on the sides and the rear of the aircraft 1, as represented on the figures 4 to 6 , in order to indicate to the pilot the directions to the right, the left and the rear of the aircraft 1. The computer 13 transmits to the display device 15 a signal carrying information relating to the heading indicator 28 and to the additional indicators 29.

The method may also include a display step 220 for displaying on the display device 15 an indicator of wind 24 experienced by the aircraft 1. This display step 210 uses information provided by the anemometer 18 or the wind vane to display on the display device 15 of a wind indicator 24 indicating the direction of the wind experienced by the aircraft 1 as represented on the figure 5 and/or a wind speed value. The computer 13 receives from the anemometer 18 or from the wind vane a signal carrying information relating to the direction and/or speed of the wind, then transmits to the display device 15 a signal carrying information relating to the indicator of wind 24.

Of course, the present invention is subject to many variations in its implementation. Although several embodiments have been described, it is clearly understood that it is not conceivable to identify exhaustively all the possible modes. It is of course possible to replace a means described by an equivalent means without departing from the scope of the present invention.

Claims (16)

Method for aiding the piloting of an aircraft (1) in flight, said aircraft (1) comprising: - a structure (2), - an image capture device (11), - a first measuring device (16) for determining an attitude of said aircraft (1), - a second measuring device (17) for determining a height of said aircraft (1) relative to an area overflown by said aircraft (1), - a display device (15), and - a computer (13), characterized in that said method comprises the following steps: - determination (110) of an attitude of said aircraft (1) with said first measuring device (16), - determination (120) of a height of said aircraft (1) relative to said area overflown with said second measuring device (17), - capture (130) of at least one image of said overflown area with said image capture device (11), - display (140) on the display device (15) of a representation (20) of said overflown zone, said representation (20) comprising said at least one image, - calculation (150) by said computer (13) of a first position (33) on said representation (20) of a vertical projection on said overflown zone of a first reference point (31) of said aircraft (1) in function of said attitude and said height, - calculation (160) by said computer (13) of a second position (113) on said representation (20) of a vertical projection on said overflown zone of a second reference point (111) of said device for capturing images (11) according to said attitude, - display (170) on said display device (15) of a symbol (21) representing said aircraft (1), an origin point of said symbol (21) being positioned on said first position (33), - display (180) on said display device (15) of a horizon circle (25) representing a horizon line, said horizon circle (25) being centered on said second position (113), said diameter said horizon circle (25) being constant. Method according to claim 1,
characterized in that said symbol (21) is represented on said display device (15) with different shapes when said height is greater than a first threshold and when said height is less than or equal to said first threshold. Method according to any one of Claims 1 to 2, characterized in that the said symbol (21) is represented on the said display device (15) with variable dimensions according to the said height. Method according to any one of Claims 1 to 2, characterized in that the said symbol (21) is represented on the said display device (15) with constant dimensions when the said height is greater than a first threshold and the said symbol (21) is shown on said display device (15) with variable dimensions depending on said height when said height is less than or equal to said first threshold. Method according to any one of Claims 3 to 4, characterized in that the said method includes an additional step of calculation (165) by the said computer of the said dimensions of the said symbol (21) at least as a function of the said height. Method according to claim 5,
characterized in that said aircraft (1) comprising at least one lift rotor (3), said symbol (21) comprises a shape (212) representing said structure (2) and at least one rotor circle (213) corresponding to said at least a lift rotor (3) and said dimensions of said symbol (21) comprises dimensional characteristics of said shape (212) and of said at least one rotor circle (213), and during said additional calculation step (165), said computer (13) calculates said dimensional characteristics of said shape (212) and of said at least one rotor circle (213) as a function respectively of a diameter of said at least one lift rotor (3) and of the dimensional characteristics of said structure (4) as well as said height. Method according to any one of claims 1 to 6, characterized in that said aircraft (1) comprising at least one lift rotor (3), said first reference point (31) is a center of rotation of a lift (3) among said at least one lift rotor (3). Process according to any one of Claims 1 to 7, characterized in that said method comprises a step of displaying (190) on said display device (15) a safety circle (26) around said symbol (21) when said height is less than or equal to a second threshold, a diameter of said safety circle (26) being variable as a function of said height. Method according to claim 8,
characterized in that said safety circle (26) is centered on an intersection of the diagonals of a rectangle (265) in which said symbol (21) is inscribed. Method according to any one of claims 8 to 9, characterized in that said step of displaying (190) said safety circle (26) comprises a sub-step of calculating (195) said diameter of said safety circle (26) as a function of said height and a diameter of a lift rotor (3) of said aircraft (1). Method according to any one of Claims 1 to 10, characterized in that the said method comprises a step of displaying (200) on the said display device (15) reference marks (27) of the cardinal points and a step of displaying ( 210) on said display device (15) of a heading indicator (28) of said aircraft (1). Method according to any one of Claims 1 to 11, characterized in that the said method includes a step of displaying (220) on the said display device (15) a wind indicator (24) experienced by the said aircraft (1 ). Method according to any one of Claims 1 to 12, characterized in that the said representation (20) of the said zone overflown covers an angular field of 360° in a plane horizontal and at least 180° in a vertical plane when said attitude of said aircraft (1) is zero, said vertical plane being parallel to a direction of earth's gravity and said horizontal plane being perpendicular to said direction of earth's gravity. Method according to any one of Claims 1 to 13, characterized in that the said image capture device (11) comprises a single camera or a single photographic device fitted with a lens covering an angular field of 360° in a plane perpendicular to an optical axis (117) of said camera or still camera and at least 180° in a vertical plane parallel to said optical axis (117), said second reference point (111) being the center of said lens, said axis optic (117) being parallel to a direction of earth's gravity when said aircraft (1) has a zero attitude. System (10) for aiding the piloting of an aircraft (1) in flight, said aircraft (1) comprising a structure (2), said system (10) comprising: - an image capture device (11), - a first device (16) for measuring an attitude of said aircraft (1), - a second device (17) for measuring a height of said aircraft (1) relative to an area overflown, - a display device (15), and - a computer (13), characterized in that said system (10) is configured for the implementation of the method according to any one of claims 1 to 14. System (10) according to claim 15,
characterized in that said image capture device (11) comprises a single camera or a single photographic device fitted with a lens covering an angular field of 360° in a plane perpendicular to an optical axis (117) of said camera or said camera and at least 180° in a vertical plane parallel to said optical axis (117), said second reference point (111) of said image capture device (11) being the center of said lens.

Images