System for assisting in the guiding of an aircraft on the ground

A system for assisting in guiding of an aircraft maneuvered by an aircraft tractor on the ground, the system including at least one projection device including a laser generating a laser beam fixed to an anchor point of the fuselage of the aircraft. A fixing mechanism is configured to fix the projection device to an anchor point of the fuselage, the laser beam from each laser projector then plotting a light trace on the ground to be used to assist in guiding the aircraft on the ground. A camera can film the light trace on the ground. A remote display device includes a screen, the display device being positioned on the aircraft tractor for the screen to be visible to an operator of the aircraft tractor, each projection device being connected to the display device, the display device being configured to display the image from each projection device camera.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the benefit of and priority to French patent application No. 16 50648 filed on Jan. 27, 2016 the entire disclosure of which is incorporated by reference herein.

TECHNICAL FIELD

The present disclosure relates to a system for assisting in the guiding of an aircraft on the ground, and a method for installing the system on the aircraft.

BACKGROUND

In order to be able to park several aircraft alongside one another in an airport terminal, an aircraft hangar or any other building, it is important to be able to accurately guide the aircraft in maneuvers on the ground. In effect, the space available between each aircraft can be of the order of thirty or so centimetres whereas an aircraft wing span can typically be more than sixty metres.

Conventionally, in order to assist an operator of an aircraft tractor in positioning an aircraft with sufficient accuracy, plumb lines are fixed to anchor points located under the fuselage of the aircraft, in the plane of symmetry of the fuselage. The plumb lines thus make it possible to show the plane of symmetry of the fuselage on the ground. The operator of the aircraft tractor can then align this plane of symmetry shown by plumb lines with a marking on the ground in order to position the aircraft. Furthermore, targets on the marking on the ground make it possible to position the aircraft on the axis defined by the marking on the ground by indicating the final position of the plumb lines, the plumb lines then having to be directly above the targets.

FIG. 1shows, for example, an airport terminal comprising several placements100,101and103intended to accommodate the aircraft110,111and112. Markings on the ground120,121and122define theoretical position of the planes of symmetry of the fuselage of the aircraft110,111and112correctly positioned in their respective placements100,101and102. The aircraft111, in its stop or parking position, is parked between the aircraft110and112. The aircraft111has potentially little space to be correctly positioned in its placement101while remaining away from the aircraft110and112parked alongside. As has been stated, in practice, the distances D1and D2—D1representing the distance between the aircraft110and111and D2the distance between the aircraft111and112—can thus be of the order of thirty or so centimetres whereas an aircraft wing span can typically be more than sixty metres. An operator of an aircraft tractor used to move the aircraft111must therefore have a visual aid or a system for assisting in the guiding of the aircraft111in order to be able to perform the operation of positioning this aircraft111between the aircraft110and112with the necessary degree of accuracy.

FIG. 2is an illustration of a known system for assisting in the guiding of an aircraft on the ground. Conventionally, plumb lines201and202are used. The plumb lines201and202are fixed to anchor points present under the fuselage, located in the plane of symmetry of the fuselage, at the front and at the rear of the aircraft111and so as to show the vertical plane containing the longitudinal axis of the aircraft111. These plumb lines201and202allow an operator driving an aircraft tractor210used to move the aircraft111to see the position of the axis of the aircraft111relative to the marking on the ground121. Thus, the operator seeing the plumb lines201and202above the marking121makes it possible for the operator to ensure that the axis of the aircraft111is indeed in the vertical plane defined by the marking on the ground121, thus guaranteeing that the ends of the wings of the aircraft111will not touch the aircraft110or112. The positioning of the aircraft111on the longitudinal axis defines by the marking on the ground121is done by marking out two targets (not represented) on the ground, each target defining a vertical position for the plumb lines201and202fixed under the fuselage of the aircraft111. Thus, the positioning of the targets on the axis121makes it possible to adjust the position of the nose of the aircraft111relative to its placement101.

Although such a system is satisfactory, it is sensitive to disturbances provoked by the movements of the aircraft or by the wind, disturbances which can cause oscillations of the plumb lines and thus slow down the positioning manoeuvre. It is in fact necessary to wait for the oscillations of the plumb lines to stop to use the system for assisting in the guiding of an aircraft on the ground described previously.

Patent application US 2009/182506 A1 discloses a collision-preventing system for airplane moving on ground; such system is nevertheless not adapted for assisting in the guiding of an aircraft on the ground by an aircraft tractor.

SUMMARY

One object of the present disclosure is a system for assisting in the guiding of an aircraft on the ground, a device which is insensitive to these disturbances.

To this end, a system is disclosed for assisting in the guiding of an aircraft on the ground, the aircraft being maneuvered by an aircraft tractor, the system comprises at least one projection device, each projection device being fixed to an anchor point of the fuselage of the aircraft, each projection device comprising a laser projector, the laser projector generating a laser beam plotting at least one light trace on the ground, a spirit level integral to the laser projector, the spirit level being configured to make it possible to adjust the verticality of the laser beam generated by the laser projector, a camera making it possible to film the light trace on the ground, a fixing mechanism configured to fix the projection device to the anchor point of the fuselage and comprising an adjustment mechanism to which the laser projector is fixed, the adjustment mechanism being configured to make it possible to adjust the position of the laser projector relative to the fuselage in order to ensure at least the verticality of the laser beam generated. The system likewise comprises a display device comprising a screen, the display device being positioned on the aircraft tractor for the screen to be visible to an operator of the aircraft tractor, each projection device being connected to the display device, the display device being configured to display the image from the camera of each projection device.

Advantageously, the projection device can then be used instead of a plumb line, by using the same anchor points on the fuselage and the same targets drawn on the marking on the ground. It is also possible to transfer the display from the camera to a display device. It is thus possible to remotely and accurately guide the aircraft on the ground, typically from the driving position in the aircraft tractor.

According to an embodiment of the disclosure herein, at least one projection device is connected to a relay device, the connection between at least the projection device and the display device being made via the relay device, the connection between the relay device and the display device being made by a wireless technology.

Advantageously, the wireless connection between the relay device and the display device makes it possible to dispense with connecting cables that are particularly bulky or cumbersome when the distance between the projection device and the display device is great. The relay device is thus advantageously placed alongside the projection device and is connected to the projection device in place of a display device. The display of the image from the camera can then be transferred over a great distance.

According to an embodiment of the disclosure herein, the axis of sight of the camera of the projection device is vertical, to the ground, its upwards extension comprising the anchor point of the fuselage to which the projection device is fixed, the camera then filming the light trace on the ground under the anchor point.

According to an embodiment of the disclosure herein, the laser projector is a rotary laser level generating a plane by sweeping of the laser beam generated, the laser beam plotting a light trace on the ground and the fuselage.

According to an embodiment of the disclosure herein, the aircraft having a fuselage comprising a vertical plane of symmetry, the rotary laser level is configured to generate a vertical plane by sweeping of the laser beam, the vertical plane comprising the anchor point of the fuselage to which the projection device is fixed, the adjustment mechanism making it possible to align the light trace on the fuselage with a marker present on the fuselage in order to superimpose the vertical plane generated by the rotary laser level with the plane of symmetry of the fuselage of the aircraft.

Advantageously, the superimposition of the plane generated by the rotary laser level on the plane of symmetry of the fuselage of the aircraft makes it possible to see this plane of symmetry of the fuselage on the ground by virtue of the light trace plotted on the ground by the rotary laser level, and, through the use of a marking on the ground, accurately position the axis of the aircraft relative to this marking on the ground.

Advantageously, the vertical plane generated by the rotary laser level comprises the anchor point on the fuselage. Assuming that this anchor point belongs to the plane of symmetry of the fuselage, it is then necessary only to align the light trace on the fuselage with a single point to superimpose the plane generated by the rotary laser level with the plane of symmetry of the fuselage. In effect, the fact that the plane generated by the rotary laser level is vertical, like the plane of symmetry of the fuselage, and comprises the anchor point requires no more than an alignment with another marker included in the plane of symmetry of the fuselage. The adjustment operation is therefore facilitated because it requires only a single alignment of the light trace on a marker judiciously chosen as contained in the plane of symmetry of the fuselage.

An object of the present disclosure also relates to a method for installing a system for assisting in the guiding of an aircraft on the ground, the aircraft being maneuvered by an aircraft tractor, the system comprising: at least one projection device, each projection device being fixed to an anchor point of the fuselage of the aircraft, each projection device comprising: a laser projector, the laser projector generating at least one laser beam, a fixing mechanism configured to fix the projection device to an anchor point of the fuselage and comprising an adjustment mechanism to which the laser projector is fixed, the adjustment mechanism being configured to make it possible to adjust the position of the laser projector relative to the fuselage in order to ensure at least the verticality of the laser beam generated, the laser beam from each projection device then plotting a light trace on the ground intended to be used to assist in the guiding of the aircraft on the ground, a spirit level integral to the laser projector, a camera making it possible to film the light trace on the ground, the system also comprising a display device comprising a screen, the display device being positioned on the aircraft tractor for the screen to be visible to an operator of the aircraft tractor, each projection device being connected to the display device, the display device being configured to display the image from the camera of each projection device. The method comprises the following steps: fixing the projection device to an anchor point of the fuselage by the fixing mechanism, adjusting, by the adjustment mechanism and the spirit level of the projection device, at least the verticality of the laser beam generated by the laser projector, the laser projector then plotting a light trace on the ground intended to be used to assist in the guiding of the aircraft on the ground, fixing the display device to the aircraft tractor in a way that is visible to an operator of the aircraft tractor and connecting the projection device and the display device in order for the display device to display the image filmed by the projection device.

According to a complementary embodiment of the disclosure herein, the aircraft having a fuselage comprising a vertical plane of symmetry, the laser projector being a rotary laser level configured to define a plane by the sweeping of the laser beam, the laser beam plotting a light trace on the ground and the fuselage, the adjustment step comprises the steps of: adjusting, by the adjustment mechanism and of the spirit level of the projection device, the verticality of the plane generated by the rotary laser level and using the adjustment mechanism to make the light trace on the fuselage generated by the laser beam from the rotary laser level coincide with at least two markers present on the fuselage in order to superimpose the vertical plane generated by the rotary laser level on the plane of symmetry of the fuselage.

According to a complementary embodiment of the disclosure herein, the vertical plane defined by the sweeping of the laser beam comprising the anchor point of the fuselage when the projection device is fixed to this anchor point, the step of making the light trace generated by the laser beam from the rotary laser level coincide on the fuselage is done by using a marker present on the fuselage in order to superimpose the vertical plane generated by the rotary laser level on the plane of symmetry of the fuselage.

DETAILED DESCRIPTION

FIG. 3is a schematic illustration of the architecture of a device300, called projection device300, making it possible to assist in the guiding of an aircraft111on the ground according to an embodiment of the disclosure herein. The projection device300for assisting in the guiding of the aircraft111on the ground comprises fixing mechanism303for fixing to an anchor point of the fuselage of the aircraft111, for example an anchor point used to fix the plumb line201or202. The fixing mechanism303comprises mechanism(s) for adjusting the position of the device relative to the fuselage. The fixing mechanism303for fixing to the fuselage can comprise a ball lock pin that can be inserted into an anchor point or housing provided for this purpose under the fuselage of the aircraft111. The fixing mechanism303can conform to the standard NSA9501-100. The projection device300comprises a laser projector301.

According to a first embodiment of the disclosure herein, the laser projector301generates a laser beam.

According to a second embodiment of the disclosure herein, the laser projector301is a rotary laser level301, that is to say that the laser beam generated by the laser projector301is deflected by a rotating mirror in order to define a plane by sweeping of the laser beam. In other words, the rotary laser level301is configured to define a plane by sweeping of the laser beam.

According to an embodiment complementing the second embodiment of the disclosure herein, the plane defined by sweeping is vertical and comprises the anchor point of the fuselage when the device is fixed to this anchor point.

In the case of a laser projector301generating a laser beam, the fictitious axis defined by the laser beam can likewise comprise the anchor point of the fuselage to which the device300is fixed, the spot light trace then defined being on the ground on the vertical from the anchor point.

The laser beam from the laser projector301plots a light trace on the ground intended to be used to assist in the guiding of the aircraft111on the ground. In the case of a laser projector301with a single laser beam, the light trace is a spot trace, on the ground and in an axis of the laser projector301. In the case of a laser projector301of rotary laser level type, the light trace is a light line on the ground and on the fuselage of the aircraft111.

According to an embodiment of the disclosure herein, the rotary laser level301comprises an automatic levelling system, that is to say the rotary laser level301can generate a vertical plane independently.

According to a complementary embodiment of the disclosure herein, the device300comprises a spirit level304integral to the rotary laser level301, the spirit level304being used to check the verticality of the rotary laser level301. The adjustment mechanism for the fixing mechanism303make it possible to ensure the adjustment of the spirit level304and therefore the verticality of the plane generated by the rotary laser level301. The adjustment mechanism for the fixing mechanism303of the device also makes it possible to superimpose the vertical plane generated by the rotary laser level301with the plane of symmetry of the fuselage of the aircraft.

According to a complementary embodiment, the projection device300comprises a camera302. The camera302makes it possible to film the ground under the aircraft111, and therefore see the position of the light trace on the ground relative to the marking on the ground121. It is thus possible to transfer the display of what is filmed by the camera302to another display device comprising a screen, for example a display device404described hereinbelow.

Advantageously, the axis of sight of the camera302is vertical and comprises the anchor point of the fuselage when the projection device is fixed to this anchor point and the plane generated by the rotary laser level301is superimposed on the plane of symmetry of the fuselage. The camera302then films the light trace on the ground located under the anchor point, vertical to it. In other words, in this case, the camera302films the ground directly under the anchor point. Thus, in this position, the camera302aims along the same vertical axis as a plumb line201or202which would be fixed to the same anchor point of the fuselage. Thus, if a position of the aircraft above the marking line on the ground121is obtained in the known solution when the plumb lines201or202are vertical to a target placed on the marking121, the same position of the aircraft111is obtained when this same target is in the axis of sight of the camera302. In other words, the targets placed for an implementation of the known solution using plumb lines can be reused according to this embodiment of the disclosure herein.

FIG. 4is a schematic illustration of the implementation of a system for assisting in the guiding of an aircraft111on the ground according to an embodiment of the disclosure herein. In this embodiment, the laser projector301is a rotary laser level. The aircraft111is moved or maneuvered on the ground by an aircraft tractor210, the aircraft tractor210being driven by an operator. The system for assisting in the guiding of the aircraft111on the ground comprises projection devices401and403for assisting in the guiding of the aircraft111on the ground, the projection devices401and403in the embodiment described inFIG. 4comprising cameras. The projection devices401and403are fixed to anchor points under the fuselage of the aircraft111. The system comprises a display device404, comprising one or more screens, positioned on the aircraft tractor210for the screen or screens to be visible to the operator of the aircraft tractor210when manoeuvring the aircraft111.

The projection device401is connected to the display device404by a wired link which is not represented. The projection device403is connected to the relay device402by a wired link that is not represented. The relay device402is connected to the display device404by a wireless link, for example of Wi-Fi (Wireless Fidelity) type. The display device404comprises a connection for one or more wired links, each wired link making it possible to connect a projection device according to the projection device300comprising a camera described previously, here the projection device401. The display device404comprises a wireless connection, making it possible to connect the relay device402, the latter being connected via a wired link to the projection device403. The projection device403is connected to the display device404via the relay device402which ensures the conversion of the connection from a wireless technology to a wired technology.

In other words, the projection devices401and403can be connected directly to the display device404via a wired link. Only, the projection device403being positioned at the rear of the fuselage of the aircraft111, a relay device402is used as relay to avoid the use of an excessively long wired link between the devices404and403. The projection device403is therefore connected via a wired link to the relay device402. The relay device402ensures a conversion of this wired link to a wireless technology in order to allow the connection of the projection device403to the display device404.

The connections between the different devices, wired or wireless, make it possible to transport data streams, the data streams corresponding for example to video data streams, typically what is filmed by the cameras of the projection devices401and403.

Each projection device401or403comprises mechanism(s) for fixing the projection device401or403to an anchor point located under the fuselage of the aircraft111, the fixing mechanism comprising mechanism(s) for adjusting the position of the projection device401or403relative to the fuselage of the aircraft111and a rotary laser level301. The rotary laser level301is configured to generate a plane by sweeping of the laser beam. The mechanism(s) for adjusting the position of each projection device401or403make it possible to generate a vertical plane and superimpose this vertical plane with the plane of symmetry of the fuselage of the aircraft111.

Each projection device401or403comprises a spirit level integral to the rotary laser level, the spirit level being configured to make it possible to ensure the verticality of the plane generated by the rotary laser level. The mechanism(s) for adjusting the position of each projection device401or403make it possible to adjust the position of the rotary laser level relative to the anchor point of the fuselage, and consequently obtain the verticality of the plane.

Each projection device401or403comprises a camera. Each camera films under the aircraft and makes it possible to see the position of the light trace relative to the marking on the ground121. According to a complementary embodiment, each camera is configured for its axis of sight to be vertical, aiming towards the ground, and for the upward extension of the axis of sight to include the anchor point of the fuselage of the aircraft111when the vertical plane generated by the rotary laser level is superimposed with the plane of symmetry of the fuselage of the aircraft. The axis of sight then corresponds to an aiming of the camera302vertically downwards from the anchor point.

The display device404is configured to display the image or the video from the camera of each projection device401and403. The data streams corresponding to the images or videos captured by the cameras pass via the wired or wireless connections between the devices, possibly by passing through the relay device402in the case of the projection device403.

The devices401,402and403are fixed to anchor points of the fuselage of the aircraft111. The projection device401can be fixed to the same anchor point of the fuselage of the aircraft111as that used to fix the plumb line201in the known solution described previously. Likewise, the projection device403can be fixed to the anchor point in place of the plumb line202. Advantageously, that makes it possible for the solution that is the subject of the disclosure herein to be compatible with the marking on the ground used by the plumb line-based known solution illustrated inFIG. 2if the axes of sight of the cameras of the projection devices401and403are vertical to the anchor points.

FIG. 5is a flow diagram of a method for installing a projection device300for assisting in the guiding of an aircraft111on the ground according to an embodiment of the disclosure herein. The projection device300concerned can be the projection device401or the projection device403as illustrated inFIG. 4. In this embodiment, the laser projector301is a rotary laser level.

In a first step510, the projection device300is fixed to an anchor point located under the fuselage of the aircraft111. Advantageously, the anchor point is one of the anchor points to which the plumb lines201and202are fixed in the known solution illustrated inFIG. 2. The anchor point is then contained in the plane of symmetry of the fuselage of the aircraft111. The projection device300is fixed to the anchor point of the fuselage of the aircraft111by the fixing mechanism303. The fixing can be done by locking a ball lock pin, for example of NSA 9501-100 type, in the anchor point of the fuselage. It may be necessary to mark an orientation of the projection device300before fixing this device to the anchor point of the fuselage.

According to an embodiment, the fixing step510is done in order for the adjustment mechanism for the fixing mechanism to be in contact with the fuselage. The adjustment mechanism can for example comprise three rods terminated by blocks, each block being designed to bear on the fuselage, each rod being able to be adjusted lengthwise in order to adjust the position of the projection device300by acting on the length of the three bearing rods.

The adjustment mechanism can comprise a guide way in order to adjust the positioning of the projection device300in translation relative to its anchor point. The adjustment mechanism can comprise a ball joint, allowing a certain degree of rotation of the projection device about the anchor point under the fuselage, the ball joint being able to comprise an adjustment mechanism in order to block the ball joint in a position.

If the projection device300comprises a camera, the projection device300comprises a connection allowing for the connection of a cable. The cable allows for a wired link in order to allow for the transfer of the data corresponding to a video stream from the camera. The other end of this cable is intended to be connected either to the relay device402in the case where the projection device300is the projection device403, or directly to the display device404in the case where the projection device300is the projection device401. In the first case, the projection device403and the display device404are connected via a wireless link, for example of Wi-Fi type. This wireless link advantageously makes it possible to dispense with a long cable which would be cumbersome. Advantageously, the relay device402is placed under the fuselage so as to ensure a direct propagation to the display device404of the radio waves used for the wireless link.

In a second step520, the position of the projection device300is adjusted by the adjustment mechanism and the spirit level304in order to ensure the verticality of the plane generated by the rotary laser level301and ensure that this plane includes the anchor point of the fuselage. For example, it is possible to act on the length of the three rods bearing on the fuselage of the aircraft111in order to act on the rotation of the projection device300about a ball joint ensuring the link to the fixing at the anchor point.

If the rotary laser level301does not comprise an automatic levelling system, the step520makes it possible to guarantee the verticality of the plane generated by the rotary laser level301and, at the same time, guarantee that the vertical plane thus generated by the rotary laser level301does indeed include the anchor point of the fuselage of the aircraft111. In this case, the rotary laser level301is configured for the plane swept by the laser beam to include the position of the anchor point.

If the rotary laser level301comprises an automatic levelling system, the adjustment of the spirit level304makes it possible to ensure that the vertical plane generated by the rotary laser level301does indeed include the anchor point of the fuselage of the aircraft111. In this case, the projection device300is configured for the plane generated by the rotary laser level301to include the anchor point when the spirit level is adjusted. In other words, the vertical plane generated by the rotary laser level301automatically and the vertical plane including the anchor point and parallel to this vertical plane generated by the rotary laser level301, are superimposed when the spirit level is correctly adjusted. If the spirit level is not correctly adjusted, then the plane generated by the rotary laser level301still remains vertical since the rotary laser level includes an automatic levelling system. However, this plane generated by the rotary laser level301would not include the anchor point.

This step520also allows for the correct positioning of the camera302when the camera302is configured to film along a vertical axis when the vertical plane generated by the rotary laser level301is superimposed with the plane of symmetry of the fuselage of the aircraft111.

In a step530, the vertical plane generated by the rotary laser level301is superimposed on the plane of symmetry of the fuselage by the adjustment mechanism for the fixing mechanism. This step may require only a simple rotation of the projection device300about the vertical axis passing through the anchor point of the fuselage. It may however be necessary to then readjust the adjustment mechanism of the fixing mechanism303in order to restore the adjustment of the spirit level304. In effect, the adjustment of the fixing mechanism may be disturbed by the rotation. Such is the case if, for example, the fuselage has defects on its surface or a curvature which is such that blocks bearing on the fuselage in one position would no longer be so after the rotation. The superimposition is verified by the alignment of the light trace plotted by the rotary laser level301on the surface of the fuselage of the aircraft111with at least one marker. The marker is for example a water drain present on the fuselage and placed in the plane of symmetry of the fuselage. In other words, it is verified that the light trace plotted on the fuselage of the aircraft111passes through at least this marker. Any marker present under the fuselage and placed in the plane of symmetry of the fuselage can be used for this alignment. The plane of symmetry of the fuselage of the aircraft111is vertical and the anchor point is included in the plane of symmetry of the fuselage. Knowing that, the verticality of the plane generated by the rotary laser level301and the fact that this plane contains both the anchor point of the fuselage and another, different, marker, also present in the plane of symmetry of the fuselage, guarantee the superimposition of the plane generated by the rotary laser level301and the plane of symmetry of the fuselage of the aircraft111. The light trace plotted by the rotary laser level301on the ground then corresponds to the axis of the aircraft111. In other words, the light trace on the ground then corresponds to the intersection of the plane of symmetry of the fuselage with the ground. The projection device300can be used for the guiding of the aircraft111by comparing the light trace plotted on the ground with the marking on the ground121

The display device404makes it possible to transfer the display from the cameras of the projection devices401and403. The display device404is positioned on the aircraft tractor210for its screen or screens to be visible to the operator of the aircraft tractor210. The display device404can comprise one or more screens in order to display, either simultaneously or sequentially, the displays from the cameras of the projection devices401and403.

According to an alternative embodiment, the projection device300may not include a camera. The comparison between the position of the light trace and the marking on the ground121can then be done directly by eye by the operator of the aircraft tractor210. The devices402and404are not useful in this situation.

According to an embodiment of the disclosure herein, a single projection device300is used, for example the projection device401or the projection device403.

According to an embodiment of the disclosure herein, two or more devices300are fixed under the fuselage of the aircraft, for example three devices300. The number of devices300to be used can be chosen according to the size of the aircraft111to be guided on the ground. It should be noted that the light traces from the different projection devices300are merged since they all define one and the same axis on the ground.

According to an embodiment of the disclosure herein, one or more devices300are used in association with one or more plumb lines201or202.

According to an embodiment of the disclosure herein, the projection device300comprises a fixing, called gauge rod fixing, making it possible to fix a plumb line. This fixing is such that, when the spirit level304is adjusted and the vertical plane generated by the rotary laser level301is superimposed with the plane of symmetry of the fuselage of the aircraft111, then the plumb line fixed to the so-called gauge rod fixing indicates a direction contained in the plane of symmetry of the fuselage. In other words, in this case, the plumb line indicates a position above the light trace plotted by the rotary laser level301. That makes it possible to check that the plane generated by the rotary laser level301is vertical.

If the projection device300comprises a camera302, and the axis of sight of the camera302is vertical and comprises the anchor point of the fuselage when the projection device is fixed to this anchor point, then the end of the plumb line fixed to the so-called gauge rod fixing is in the axis of sight of the camera302. Advantageously, it is then possible to check the projection device300is correctly adjusted by using a plumb line fixed to such a fixing called gauge rod fixing.

Generally, if the projection device300is intended to be fixed to an anchor point under the fuselage contained in the axis of symmetry of the fuselage, it is advantageous for the rotary laser level301to be configured in order for the plane generated by the sweeping of the laser beam to include the anchor point when the projection device is fixed to this anchor point. Thus, the adjustment of the superimposition of the plane generated by the rotary laser level301with the plane of symmetry of the fuselage is guaranteed by two steps. First of all, a step of adjustment of the verticality of the plane generated by the rotary laser level301. This adjustment is formed by the adjustment mechanism of the fixing mechanism of the projection device300, the spirit level304making it possible to ensure the correct adjustment of the verticality. Then, a step of alignment of the light trace plotted by the rotary laser level301on the fuselage with at least one marker present on the fuselage and contained in the plane of symmetry of the fuselage. The step of alignment can implement adjustment mechanism(s) making it possible to rotate the projection device300about the vertical axis passing through the anchor point. A single marker is sufficient to obtain the desired result, that is to say the superimposition of the plane generated by the rotary laser level301with the plane of symmetry of the fuselage since the anchor point itself forms part of the plane of symmetry of the fuselage. The operations of adjustment of the projection device300in order to obtain the desired superimposition of the planes are therefore simple adjustment steps, the step of rotation about a vertical axis to obtain the alignment on a marker not disrupting the verticality set in the preceding step. Thus, the projection device300can be adjusted simply in two steps, without having to proceed with iterative steps.

According to an alternative embodiment, the projection device300is intended to be fixed to an anchor point under the fuselage, the anchor point not forming part of the plane of symmetry of the fuselage. The adjustment mechanism of the projection device300then comprise mechanism(s) for translating the rotary laser level301in order to allow for an adjustment of the position of the rotary laser level301relative to the fuselage. The adjustment of the superimposition of the plane generated by the rotary laser level301with the plane of symmetry of the fuselage is guaranteed by two steps. First of all, a step of adjustment of the verticality of the plane generated by the rotary laser level301. This adjustment is performed by the adjustment mechanism of the fixing mechanism of the projection device300, the spirit level304making it possible to ensure the correct adjustment of the verticality. Then, a step of alignment of the light trace plotted by the rotary laser level301on the fuselage with at least two markers present on the fuselage and contained in the plane of symmetry of the fuselage. It is in fact here necessary to align the light trace plotted by the rotary laser level301on the fuselage with at least two markers contained in the plane of symmetry. It may be possible to obtain the desired alignment by proceeding with successive translation and rotation steps. This latter step is therefore iterative. This adjustment mode, while it makes it possible to ultimately obtain a satisfactory adjustment making it possible to obtain an assistance in the effective guidance of the aircraft111on the ground, is not however as simple to implement as in the case where the projection device300is intended to be fixed to an anchor point contained in the plane of symmetry of the fuselage. It is however not always possible to have such an anchor point.

According to yet another possible embodiment, the projection device300is intended to be fixed to an anchor point under the fuselage, the anchor point not forming part of the plane of symmetry of the fuselage, and the laser projector generates a laser beam plotting at least one light trace on the ground, vertical to the anchor point. In this case, a specific marking is provided on the ground, which is intended to be located vertical to this anchor point when the aeroplane is in the desired position.

The use of a projection device300comprising a rotary laser level301makes it possible to advantageously replace the known solution using plumb lines. In effect, a system comprising one or more projection devices300is insensitive to the disturbances of wind or aircraft movement type.

The use of a projection device300comprising a camera302makes it possible to place a target on the marking on the ground, the correct position of the aircraft111above the marking on the ground121being obtained when the target appears in the axis of sight of the camera. This solution makes it possible to advantageously replace the known solution with plumb lines but requires new targets to be prepositioned in the axis of sight of the camera. This solution further makes it possible to simplify the work of an operator who can more easily view, on a display device404, the position of the light trace relative to the marking on the ground. That is particularly true for a very long aircraft, the operator possibly not being able to see a plumb line placed at a great distance.

The use of projection devices300comprising a camera302, the axis of sight of which is vertical and includes the anchor point of the fuselage when the projection device is fixed to this anchor point, makes it possible to advantageously replace the plumb lines201or202of the known solution. In effect, the solution is then insensitive to wind or movements of the aircraft. Furthermore, the targets on the marking121allowing for the positioning of the aircraft on the longitudinal axis used in the known solution with plumb lines can be reused in this solution, the aircraft then being in its parking position when these same targets appear in the axis of sight of the cameras302.