Technical background

EP 2 109 063 A2 refers to a Visual docking guidance system (VDGS) adapted to determine a yaw angle of an aircraft related to a centerline defining a parking position at an aircraft stand. An optical laser is used to scan the shape of the aircraft. Hereby the aircraft nose tip is detected which in optimal position is located at a symmetry axis of the VDGS. Additionally shape of the aircraft left and right adjacent to the nose tip is detected. By analyzing the symmetry the yaw angle can be detected as described based on figure 15A of EP 2109063 A2. The yaw angle is a deviation between the orientation of the aircraft to a line which intersects the VDGS. The disadvantage is that this system merely works in a situation where the VDGS is in line with the centerline of the aircraft stand.

When the VDGS of EP 2 109 063 A2 is operated at a stand with more than one centerline, all centerlines intersect with the position of the VDGS (see EP 2 109 063 A2, figure 15A and the description).

EP 2 109 063 A2 teaches also that a position of the VDGS is preferably located in front of the nose of an aircraft to be parked. Therefore the horizontal capture zone of the DGS is in particular max 50 degree (see EP 2 109 063 A2, [0052]). So the aircraft is scanned by a laser device at a horizontal scanning angle of max. 25 degree.

Sategate Group’s“SAFEDOCK Manual" (XP055612526) discloses a VDGS using a laser scanner for detecting the position of an aircraft. In general the VDGS requires a position if the VDGS in front of the nose of the aircraft. Therefore an angle between the optical axis of the VDGS and the approaching aircraft may not exceed 20 degrees (chapter 2 installation, para 2.5). A stop position must be less than 24 degree angle from the Laser Scanning unit to the aircraft nose (chapter 2 installation, para 2.2). A horizontal scanning area is limited to +/-30 degrees (chapter 2 installation, para 3.1.7.2; the side angle mentioned herein refers merely to the location of the scanning plate).

US 2008 _/ 0157947 A1 discloses a system for guiding an aircraft to a parking position. A matrix of RFID sensors are provided in in the apron ground. The RID sensors cooperate with an RFID tag provided at the front wheel of the aircraft. This systems requires that aircrafts and airports have to be equipped with corresponding components: otherwise it would not work universally. In combination with the huge effort to install the RFID sensors on the apron of each stand that may be the reason why is was never implemented. In contrast the present successful VDGS system base on optical systems , which require no specific equipment at the aircraft and are easy to install.

A variety of aircraft types, with the same aircraft family are of versions have identical frontal appearance. Different aircraft types, which differ in the version within the same aircraft family (e.g. Airbus A318, A319, A320, A321) differ in their aircraft length and their door positions, so that different stop positions may be allocated to the different aircraft types. Consequently for proper docking it is helpful to know, which version of an aircraft family is appearing at the stand. But since the variety of aircraft versions within one family have an identical frontal appearance, identification from a frontal view is often not reliable. Consequently it is also an object of the present invention to improve reliability in identification of the aircraft version within an aircraft family. Nowadays airports are provided with flexible stands at which an aircraft can be docked to a terminal building, commonly referred to as a MARS (Multiple Aircraft Ramp System) stand (see figure 1). Here one single stand 20 comprises more than one centerline. An aircraft 1 can be parked at different stop positions S, defined by centerlines C which are oriented angular to each other or which are arranged parallel offset to each other. So in one situation a stand may accommodate one larger aircraft (figure la) at centerline Cl or and in another situation the stand may accommodate at least one smaller aircraft at centerline C2 or two aircrafts at the same time at centerlines C2 and C3. Additionally each centerline may comprise more than one stop position.

To each of the centerlines one Visual docking guidance system (VDGS) 30 is assigned as shown in figure 2. The VDGS 30 provides positional information to the pilot of the aircraft 1 which arrives at the stand. VDGS 30 currently usual in the market are each assigned to one centerline and are located in line with the centerline. A 3D laser scanner is located in line with the centerline which can detect the shape and position of the aircraft 1 arriving at the stand. If the aircraft 1 arrives at the stand offset from the assigned centerlines C, the VDGS 30 detects asymmetries in the scanned profile with reference to the centerline as a symmetry axis. Based on the detected asymmetry the lateral offset can be determined. Such a VDGS is disclosed in WO 2001/035 327 Al . When used in a MARS stand one individual VDGS 30 system is required for each centerline of the plurality of centerlines.

EP 1 015 313 B1 discloses a docking system for airport terminals, having a positioning apparatus as part of a gate operating system of an airport terminal, by means of which an aircraft can be guided to a parking position. The docking system comprises an advisor and guidance display segment AGDS (Informations- und Leitanzeigesegment AGDS), which is adapted to display spatial information to the pilot in the aircraft. In case the stand comprises a plurality of centerlines the system may comprise a plurality of guidance display segment AGDS, each of which is associated to an associated centerline (para. [0016]).

It is the object of the invention to provide an improved method and apparatus for guiding an aircraft to the stop position at an airport stand. The object is solved by a method and a system according to the main claims; embodiments are disclosed in the subclaims and the description.

In the inventive method of operating a Visual docking guidance system at an airport stand, the airport stand comprises a plurality of centerlines; the Visual docking guidance system is adapted to provide visual information to the pilot of an aircraft when the aircraft is approaching the stand along a centerline. The Visual docking guidance system in particular is located in proximity of the centerlines to enable the docking guidance system to provide positional information of the aircraft to the pilot of the aircraft when the aircraft is approaching the stand at one of any of the plurality of centerlines.

The inventive method comprising the following steps:

Selecting one selected centerline out of the plurality of centerlines;

Operating the VDGS on basis of the selected centerline out of the plurality of centerlines.

In contrast to conventional VDGS the inventive VDGS has the capability to operate with respect to a plurality of centerlines. Consequently the number of VDGS units can be reduced compared to conventional systems. I particular the positional information of the aircraft is displayed in dependency of the selected centerline selected out of the plurality of centerlines.

In an embodiment the positional information is determined by calculating a spatial relation between an aircraft location and the selected centerline selected out of the plurality of centerlines, in particular a stop position located on the selected centerline. In particular the displayed positional information varies if another centerline out of the plurality of centerlines is selected.

In an embodiment the step of Operating comprises providing, in particular displaying, an indication to which selected centerline out of the plurality of centerlines the displayed positional information refers to. With the help of this information the pilot can allocate the provided information to the correct centerline, avoiding any misunderstanding of the provided information. In an embodiment during the step of displaying the positional information is displayed on a predetermined display, wherein the predetermined display is used for displaying the positional information independently of the selected centerline out of the plurality of centerlines. In other words: there is one common display which is used, no matter on which of the plurality of centerlines the aircraft is to be parked. This reduces the number of displays; conventional VDGS need one display per centerline.

In an embodiment the method comprises the step of providing spatial centerline information for a plurality of centerlines of the single stand within a database. The step of Operating comprises retrieving a spatial centerline information for a selected centerline out of the spatial centerline information stored for the plurality of centerlines for one stand within the database; and

Displaying the positional information of the aircraft in dependency of the retrieved spatial centerline information out of a plurality of spatial centerline information, in particular calculating the spatial relation between the aircraft location and the retrieved spatial centerline information.

The database consequently comprises the spatial reference information which is needed for determining the spatial relation between the airport stand and the approaching aircraft.

In an embodiment the VDGS comprises a display, in particular an electronic visual display.

During the step of Operating a video sequence is presented on the display in a manner that the pilot of the approaching aircraft can see the content of the video sequence. Conventional VDGS has merely a predefined and limited scope of graphical elements, which can be presented to the pilot. The invention provides now the opportunity to provide freely programmed visual information to the pilot including real time images, in particular video sequences.

Instead or additionally to the presentation of numbers or arrows on the display the pilot can see a real time presentation of the situation on the apron in the vicinity of the aircraft in particular of the front wheel. In particular the video sequence is focused on the front wheel of the approaching aircraft. This real time presentation may provide additional information to the pilot with respect to any deviation from the centerline or any obstacles in an easy and effective manner.

In an embodiment the video sequence comprises images of the apron area within the stand of a certain range, captured by a camera focused on the apron area of the stand. In particular the step Displaying presents a representation of the positional information and/or the spatial relation within one image of a correct stop position and the front wheel of the aircraft captured by a camera in real time. By displaying both, the stop position and the front wheel, together on the display the pilot can see the spatial relation without the need of any calculating the spatial relation.

In an embodiment the images presented to the pilot on the display are horizontally mirrored with respect to the images originally captured by the camera. In an example the front wheel is positioned left of the centerline. From the cameras view (which is the opposite direction of the pilots view) the front wheel is then positioned right of the wheel, which could be confusing to the pilot. By mirroring the displayed images the front wheel is displayed left of the centerline, so that the pilot can adjust the position intuitively by steering in the right direction.

In an embodiment the range of the apron area presented on the display selectively varies during aircraft is approaching. In particular the range varies in a manner that the front wheel and the correct stop position are both displayed on the display and/or that a zoom factor of the displayed images increases as a distance between the front wheel and the correct stop position decreases. This has the advantage that the resolution of spatial information is increasing with the pilots needs. When the aircraft is far away from the pilot needs merely rough information of the distance; when the aircraft is merely few meters away from the correct stop position a more detailed view of the situation is required.

In an embodiment the display presents a stop position indication, highlighting the correct stop position out of a plurality of stop positions displayed on the display. Because the image may show several stop position painted on the apron, the pilot needs to know, which one is the correct stop position. This indication may point to the correct stop position and may avoid any confusion.

In an embodiment in a first identification step the aircraft type is identified with the help of transponder signals received; and in case the first identification step does not deliver a reliable result a second identification step is performed using an optical scan, in particular a laser scan, of the aircraft and comparing the scan with a model, in particular a 3D model, stored in a database. This provides a redundancy in detecting the aircraft type.

The invention refers also to a Visual Docking guidance system (VDGS) to be positioned at an airport stand, the airport stand in particular comprises a plurality of separate centerlines. In particular the VDGS is adapted to conduct a method according to any of the preceding claims. The Visual docking guidance system 30 comprising: a scanner adapted to determine the position of an aircraft at the airport stand, a display mounted at the stand and adapted to provide positional information of the aircraft to the pilot in the aircraft in a visual manner. In an embodiment the display is suitable to display an image recorded by a video camera, in particular the display comprises an electronic visual display.

In an embodiment the Visual Docking guidance system has a display, in particular an electronic visual display, which is adapted to display an image or video sequence captured of an apron area of the stand by a camera in real time.

In an embodiment the Visual Docking guidance system is adapted to determine the position of the aircraft within the stand in real time and to focus the visual information provided on the display based on a determined position of the aircraft, in particular so that a spatial relation between the front wheel of the aircraft and the selected centerline is displayed on the display.

In an embodiment on the display an image of the apron is shown, wherein in the image a plurality of stop positions are comprised. The display provides an indication, which of the stop position of the plurality of stop positions is the correct stop position for the current docking procedure.

In an embodiment the VDGS comprises a 3D-laser scanner, wherein the laser scanner is adapted to provide laser beams of more than one color, in particular of at least three colors; this could improve the measuring results since the color to be used during scanning can be selected based on reflection intensity. E.g. a blue laser will generate better reflections on a blue surface than a red laser.

In an embodiment the VDGS is adapted to conduct a method as described within this application.

In an embodiment the VDGS is located offset of at least one centerline of the plurality of centerlines. In particular at least two of the centerlines do not intersect each in the area of the apron and/or two centerlines are aligned parallel to each other.

In an embodiment the stand comprises a passenger boarding bridge, wherein the passenger boarding bridge can be docked to an aircraft located at each one of the plurality of centerlines of the stand and /or at one of the stop positions defined by the centerlines.

In an embodiment the VDGS is adapted that during operation exactly one scanner, in particular one 3D-laserscanner, is used to detect the position of the approaching aircraft, in in particular:

- independently from the selected centerline by one common scanner which is associated to a plurality of centerlines within the stand and in particular which is attached to a main housing, the scanner is located off centered to at least one of the associated centerlines, or - by one of a plurality of scanners, each of the scanners is centered to one centerline, in particular at least one of which is attached to an auxiliary housing separate to the main housing.

In an embodiment the step of Operating comprises a step of Determining a position of the aircraft and/or identifying of the aircrafts type and/or version by performing an optical scan of at least parts of the aircraft, in particular by using an optical scanner.

In an embodiment the scanner is scanning the aircraft, in particular when the aircraft is located on the selected centerline and/or located at the stop position. During scanning the aircrafts nose is located at an orientation relative to a scanning device in a manner, that in top view a line through the aircrafts nose and a scanning device is orientated relative to the selected centerline at an angle (AOS) of at least 35 degrees, in particular at least 45 degrees. In a more particular embodiment during scanning a laser beam hitting the nose is in top view oriented relative to the selected centerline at said angle (AOS) of at least 35 degrees, in particular at least 45 degrees. This orientation enables a scan of the aircraft more in side view than the frontal view used in the conventional VDGS. This orientation improves the ability to detect the position of the aircraft more reliable in particular for aircrafts which are of a family having different versions, since the distinguishing features of such aircraft are better visible in aside view scan.

In an embodiment a display, in particular the predetermined display and/or an electronic visual display, which is used and/or adapted to be used for displaying the positional information is housed within a main housing, in particular wherein the main housing is also housing a scanner, in particular a 3D laser scanner.

In an embodiment the display, in particular the display for presenting real time images recorded by the camera, is provided by an anti reflecting device in particular covered by an anti-reflecting coating and/or by an anti-reflecting cover.

In an embodiment the display is adapted to be operated in a day-light modus and in a night time modus.

In an embodiment a Method is provided for adding a new centerline to a stand, wherein a Visual docking guidance system of any of the preceding claims or a Visual docking guidance system operating according to any of the preceding claims is located at the stand. Herein the following steps are comprised:

marking a new centerline to the apron ground within the stand;

establishing a remote connection via the internet between a database of the visual docking guidance system and a remote computer;

in particular accessing the database of the docking guidance system from the remote computer; adding a new database entry in the database, wherein the new database entry comprises spatial information of the added centerline.

Since the VDGS according to the present invention needs not to be positioned on line with a centerline, a new centerline can be easily programmed onto the VDGS. No mechanical work or adjustments to the VDGS need to be performed to the hardware; merely the database is to be updated by spatial centerline information.

All features, embodiments and advantages mentioned with respect to the device and installation are also applicable for the method and vice versa.

Features of method claims (isolated or combined with features of referenced claim) can be combined with device claims; features of device claims (isolated or combined with features of referenced / preceding claims) can be combined with method claims.

Brief description of the drawings

The invention is described with reference to the figure; herein show figure 1 a conventional MARS stand in top view;

figure 2 the conventional MARS stand of figure 1 provided with one VDGS per centerline; figure 3 the MARS stand provided with one inventive VDGS;

figure 4 the principle of scanning an aircraft by the VDGS;

figure 5 an aircraft scan and stored 3D models of aircrafts;

figure 6 the scan and the 3D virtually model arranged in the apron;

figure 7 the principle of matching the scan with the 3D model;

figure 8 the VDGS operating in case the third centerline C3 being the selected centerline; figure 9 the VDGS operating in case the first centerline C3 being the selected centerline; figure 10 two different configurations of the inventive VDGS;

figure 11 the VDGS having an electronic visual display in three situations during parking; figure 12 a database having spatial centerline information of a plurality of centerlines within one stand;

figure 13 the database having an additional spatial centerline information;

figure 14 details of a suitable scanning device used a) in front view attached at aVDGS, b) more detailed in side view; figure 15 and 16 the scanning device of figure 14 during scanning at different swivel angles; figure 17 illustrated the distinguishing features of aircraft of different versions within one aircraft family;

figure 18 a situation on the stand similar to figure 3, wherein the aircraft is located in a particular orientation relative to the scanning device in top view;

figure 19 the situation of figure 17 in side view.

Detailed description of embodiments of the invention

Figure 3 shows an airport stand 20 having a plurality of centerlines, in this example a first centerline Cl, a second centerline C2 and a third centerline C3. The second and the third centerline are arranged distant and parallel to each other, the first centerline Cl is arranged angled to the second and the third centerline C2, C3. The stand comprises a passenger boarding bridge which can be connected to an aircraft parked at any of the centerlines Cl, C2, C3 within the stand 20, as shown already in figure 1.

A visual docking guidance system 30 is located in particular in front of the aircraft 1 when the aircraft 1 is approaching the stand along one of the centerlines C1-C3, so that the pilot sitting in the aircraft 1 can see the provided information provided by the VDGS 30. The term pilot is used synonymously for the the co-pilot.

Any of the centerlines C can be defined by geometrical parameters. For example the centerline is defined by one point SI, S2, S3 lying on the centerline Cl, C2, C3 and by one direction vector D l, D2, D3. These geometric parameters together with the centerline ID can be stored as spatial centerline information within a database 39, as shown in figure 13. The geometric parameters comprise spatial coordinates x,y,z, which refer to a common coordinate system 22. The VDGS 30 can be positioned in the origin of the coordinate system 22, but it is not required that the origin of the coordinate system and the position of the VDGS match.

In contrast to the stand 20 of the prior art (as shown in figure 1) in figure 3 merely one VDGS 30 is provided for a plurality of centerlines Cl, C2, C3. Since the centerlines Cl, C2, C3 are not in line to each other the VDGS 30 is not in line with at least one of the centerlines. Here the VDGS 30 is not in line with any of the centerlines Cl, C2, C3.

At each of the centerlines one or more parking positions SI, S2, D3 are assigned at which one aircraft can be parked. In figure 3 merely one parking position is shown on each centerline; but as described later one centerline may comprise several parking positions for different aircraft types. The coordinates of a parking position can be a geometric parameter of a centerline stored in the database 39. Also here the parking position is drawn with respect to the foremost nose position; as described later the parking position can also be defined by the wheel position, since wheel and nose of a known aircraft type have a fixed relationship within the aircraft. The application uses the term stopping position synonymously for the position of the front wheel and the position of the nose position, when the aircraft is in the correct parking position.

The VDGS 30 has a 3D laser scanner 38, the general operation of which is already described in WO 200/035 327 Al. In contrast to a known VDGS 30 the top view angular range R of the inventive VDGS 30 is in particular more than 90°, in particular at least than 150°. With reference to figure 4 the scanning operation of the scanner 38 is described. An aircraft 1 is arriving at the stand 20. The aircraft 1 has not yet reached the assigned parking position S3 on the centerline C3 and is located offset of the centerline C2. So the final parking position is not yet reached.

The scanner 38 sends out a plurality of laser beams, which are reflected by the fuselage of the aircraft 1. As a result from the scanning operation the VDGS obtains a plurality of coordinates x,y,z of points P on the fuselage of the aircraft, wherein the coordinates also refer to the common coordinate system 22. The plurality of points P obtained by scanning constitutes a point cloud 60 also called more general“the scan” 60.

The scanner may use a laser of different colors to detect. The reflection properties aircrafts may differ due to the painting on the aircraft fuselage. E.g. a blue laser beam is reflected better by a blue painted fuselage than a red laser beam. By using laser beams of different colors the scanning quality can be improved.

The VDGS 30 has already identified the type of the arriving aircraft 1 by a method as described within EP 2 660 152 A2 or EP 2 660 153 A2; in this particular example the aircraft type is an Airbus A320. The VDGS 30 has access to a database, in which a plurality of surface models 50 of known aircraft types are stored. Figure 5a shows the scan 60 in side view, figure 5b shows a 3D surface model 50 of an A320, figure 5c shown a 3D surface model of a Boeing 737. As apparent form the figures the point cloud 60 fits into the model 50 of the Airbus A320, but the point cloud 60 does not fit into the model 50 of the Boeing B737. With the help of figure 6 the step of determining the spatial relation between the aircraft location and the centerline CS selected out of plurality of centerlines C1-C3, in particular a stop position S3 located on the selected centerlines CS is described.

The stored 3D model 60 of the Airbus A320 is virtually positioned in the assigned parking position of the aircraft 1 at the stand. Thereby the nose point of the model 50 fits to the dedicated stop position S3 on the centerline C3 in top view (S3 is in top view the parking position nose point). As apparent from figure 6 the point cloud is not yet aligned to the model 50, consequently it can be determined, that the aircraft has not yet reached its dedicated parking position.

For determining the deviation of the aircraft from the dedicated parking position the points P of the point could (scan) 60 in its entirety are virtually shifted to the position of the model 50, so that the points P of the scan 50 matches with the model 60. This step is performed by means of a computer program. This shifting can be performed with a point cloud comparing tool as available in the market, e.g. a program called“CloudCompare” uses such tools (See also https://www.youtube.com/watch?time_continue=24&v=MQiD4Hj hpAU).

The step of virtually shifting the point cloud is illustrated in figure 7 in detail for the foremost nose point P of the scan 60. A from the nose point P to the parking position nose point S3 constitutes a distance vector dP (in this application also referred to as the“spatial relation”) from the aircraft nose P to the parking position nose point S3 (in top view) of the model 50. By comparing a plurality of points from the scan 60 with the model 50 in this manner a transformation matrix can be established which describes the positional difference between the scan and the model including information of a yaw angle A. Yaw angle A defines the angular deviation between the aircraft longitudinal axis and the centerline C (see yaw angle in figure 4). A dx value of dP constitutes the lateral offset, a dy value of dP constitutes the longitudinal offset. The z value is of minor relevance here.

In general the aircraft type of the approaching aircraft 1 can be determined in a first step with the help of transponder signals received. Thereby it is essential to filter the huge amount of transponder signals available in the air around the airport and to identify the individual transponder signals of the individual aircraft approaching the stand. Suitable methods for filtering are disclosed in EP 2 660 153 A2 and EP 2 660 153 A2.

In case this first step does not deliver a proper result the inventive method comprises a backup method. In this case a second identification step is performed using an optical scan, in particular a laser scan as described above. Here the scan of the aircraft can be brought into alignment with various models 50 stored in a database. The best match represents the aircraft type.

Figures 8 and 9 each show again an aircraft 1 approaching the stand 20. The aircraft 1 is not yet aligned to any of the centerlines C1-C3. However the aircraft 1 is located between the first centerline Cl and the third centerline C3 and still can be aligned in the further course with any of the first or third centerlines Cl, C3.

According to the situation of figure 8 the VDGS 30 has selected centerline C3 out of the plurality of centerlines Cl and indicates this selection on the display 37, so that the pilot can see to which positional information refers to; the indication 34 is provided on the display 37 by highlighting the centerline C3 as the selected CS. Accordingly VDGS 30 display an arrow 33 pointing in the right direction indicating that the aircraft 1 and/or at least the front wheel of the aircraft) is currently located left of the selected centerline CS=C3. Furthermore the VDGS indicates the longitudinal distance which the aircraft has to travel in forward direction to reach the stopping position S3 by a graphical distance bar 32. Additionally the VDGS provides an information 31 about the type of the aircraft (here“Airbus A320”) expected at the stand. Various alternatives may be used on how to provide the visual information to the pilot.

In case that the first centerline Cl (instead of centerline C3) is selected as the selected centerline CS, the information provided on the display 37 may significantly vary from that shown in figure 9. In Figure 8 the display shows the information which is necessary for the pilot to drive the aircraft on to the stop position SI on selected centerline CS=C1. The positional information is calculated in the same manner as previously described with reference to centerline C3, but now the model 50 is aligned to the stop position SI on centerline Cl and the spatial relation dP is calculated with respect to centerline Cl .

In contrast to figure 8 the indication 34 highlights now centerline Cl as the selected centerline (instead of centerline C3). Accordingly VDGS 30 display the arrow 34 pointing in the left direction (instead of right direction) indicating that the aircraft 1 is currently located right of the selected centerline CS=C1.

In figure 10 two basic configurations of the inventive VDGS 30 system are shown.

Figure 10a shows a first hardware configuration. Here the VDGS 30 comprises a single main housing 40, which is positioned offset with respect to at least one of the centerlines C1-C3. The main housing houses the display 70 and the 3D laser scanner 38x. Further the main housing 40 houses a camera 43 for recording images of the apron. In this specific embodiment the housing also houses a CPU 36 and a database. In particular the database can be located outside of the VDGS and access to the database can be realized via a data connection, in particular a wireless data connection.

Figure 10b shows a second hardware configuration. Here the VDGS 30 comprises a main housing 40. The main housing 40 houses the display 70. Further the main housing 40 houses a camera 40 for recording images of the apron. In this specific embodiment the housing also houses a CPU 36 and a database. In particular the database can be located outside of the VDGS and access to the database can be realized via a data connection, in particular a wireless data connection. Further the VDGS 30 comprises a plurality of auxiliary housings 41 each housing a laser scanner 38a, 38b, 38c. The laser scanner 38 are associated to at least one of the centerlines, so that in line with each centerline is one scanner 38. The components are connected to each other via a data connection 42. Further the main housing 40 houses a camera 43 for recording images of the apron. Here in main the hardware configuration of the VDGS according to WO 2001/035 327 A1 can be used, which is provided by additional scanners per additional centerline. In a modification the main housing may house one of the scanners 38a-c and may be arranged in line with one of the centerlines; then merely two (number of centerlines - 1) auxiliary housings are required.

Figure l ib shows an embodiment of an inventive hardware configuration of a VDGS. Here merely the display of the VDGS is shown comprising an electronic visual display (EVD) 371, e.g. a LCD display. The EVD 371 is suitable to display an image, text or a video sequence captured by a camera, in particular the camera 43 of the VDGS. In contrast thereto conventional VDGS displays having limited predetermined scope of graphical elements, and are not capable of displaying images and movies in real time.

Figure 11 shows the content of what is displayed display during various situations I, II, III, when an aircraft is approaching the stand. For comparison figure 11a shows a display 37 as already described within respect to figures 8 and 9. Also here content of what is displayed during the situations I, II, III is shown.

Situation I is analog to the situation shown in figure 8. The apron is recorded by the camera 43 of the VDGS 30 mounted on the main housing 40 (see figure 8). In situation I the aircraft 1 is approaching the stand 20. The approaching aircraft 1 is positioned between the first and third centerline Cl, C3. The centerline C3 is still the selected centerline CS. This selection is displayed on the EVD 371 by an indication 34; here the indication is an arrow 34 which is placed on the image of the selected centerline C3. Additionally the indication is pointed to the stopping position D3. Here the stop position is the front wheel stop position. That the aircraft is on its dedicated parking position the front wheel 11 of the aircraft 1 is to be placed on the stop position S3 as indicated by the arrow 35. As apparent from the illustrations of the other situations II, III there can be more than one stop position marked on one centerline, in particular each referring to the stop position of various aircraft types. So that the pilot can identify the correct stopping position out of a plurality of stopping positions (marked by“A320”,“A321” on apron ground) on the selected third centerline C3 the correct stopping position is also highlighted by the arrow, which constitutes in addition a stopping position indicator 35.

Important here is that the EVD 371 displays merely real time images of the relevant area of the apron. For example since centerline C3 is the selected centerline the areas of centerlines Cl and C3 are of minor interest for the pilot. Therefore the displayed images are focused on the selected third centerline C3 and the front wheel 11 of the aircraft 1. The images are zoomed in a manner, that the pilot can see the spatial relation dP between the front wheel 11 and the correct stop position S3 at any time on the EVD figuratively on the displayed images 371. In the figures the figurative spatial relation is highlighted by a curly brace and the reference sign dP. This also represents a graphical display of the longitudinal and lateral positional information 32, 33 the same time the longitudinal information 32 and lateral information 33 to the pilot.

In figure l ib the EVD 371 displays the recorded images in real time. Real time means within this application that the recorded images are displayed on the EVD simultaneous as the images are recorded by the camera 43, in particular at a maximum delay of 0.2 seconds more preferred maximum 0.1 seconds. So the pilot in the aircraft 1 can see via the EVD the centerline and the front wheel 11 of his aircraft 1 in real time.

In situation II the front wheel is further moved into the direction of correct stop position S3. The distance in lateral and longitudinal direction has decreased compared to situation I. The center of the images presented on the display is adapted, so that the stop position is displayed in a more central position on the display that during situation 1. Further the zoom Z is increased, the further the front wheel moves in direction of the correct stop position S3.

In situation III the front wheel 11 now on the correct stop position S3. The center of the images presented on the display 371 is continuously adapted, so that the stop position S3 and the front wheel 11 is displayed roughly in a central position on the display 371 and with a high zoom factor Z, which makes it easier for the pilot to position the front wheel correctly in the final phase of parking. Just for comparative matters in the figure l ib, image of situation I, the ranges 231, 2311, 23111 of the presented apron area during situations I, II and III are illustrated. As apparent the ranges used in the different situations differ significantly. The ranges 231, 2311, 23 III are selected so that a center position of the front wheel and the correct position i in main in the center of the presented image 372.

To improve readability the display is provided by a anti reflecting device in particular covered by an anti reflecting coating and/or by an anti reflecting cover. The negative effect of reflections, in particular caused by sun light, can be avoided.

The display may be operated a day-light modus with increased brightness and in a night time modus with reduced brightness of the presented information on the display. Also the used colors on the display may differ for the daylight and night time modus.

Figure 12a shows a database 39 comprising spatial centerline information of the centerlines Cl- C3 within the stand 20. For each centerline C1-C3 the database comprises a database entry 391, 392, 393. Each database entry comprises a centerline ID and various spatial centerline parameters. The spatial centerline parameters may be a direction vector D1 and/or the coordinates of one or more points on the centerline. In this particular embodiment the database entry comprises several points on each centerline, each point defining the stop position for a specific aircraft type. For example aircraft type a on centerline Cl is an Airbus A330-200. This aircraft type a has to stop at the coordinates stored under the data set for stop position a of entry 391. Figure 12b shows the relation of the centerlines painted on the apron ground.

Assuming the aircraft industry now develops a new type of aircraft, e.g. the new Boeing 747-9 or an Airbus A390. Based to the new shape and dimensions this aircraft type does not fit on any of the present centerlines C1-C3 of the present stand 20. Now the stand needs 20 to be provided with a new centerline, as shown in figure 13. In a first step the new centerline is painted on the apron ground as indicated in figure 13b. In addition the database has to be updated with a new database entry 394, having the analog parameters as described with reference to figure 12a for the new centerline. Since the VDGS 30 is not required to be positioned in line with the centerline no hardware modifications may be necessary. Updating the database (i.e. bringing the database from status of figure 12 into status of figure 13) can be performed by remote access. So in sum, the inventive VDGS 30 can be made fit for the added centerline C4 without any service operator to be present at the stand. In the embodiments merely a straight lined centerlines are shown. The invention in general is applicable for straight lined and curved centerlines.

Figure 14 shows an embodiment of a VDGS 30 having a particular scanning device 38. The Scan device 38 has a laser source 381 which for generating a laser beam LB. A laser beam mirror 382 is rotatably supported along an upright Swivel axis LS. Upright means: not necessarily vertical here, but at least temporary oriented at an acute angle aa relative to the vertical direction z.

A swivel motor 383 drives the mirror 382 so that the mirror is rotating around about the laser rotation axis LR. The mirror 382 is rotating continuously, in particular with constant speed, around 360°, which enables high scanning speeds, since the mirror is not subject to changes in the movement direction accelerations and decelerations.

The laser source 381, the mirror 382 and the drive 383 are supported by supporting frame 384. The supporting frame 384 can be swiveled around a laser swivel axis S, which is oriented in particular parallel to the apron ground and/or perpendicular to the laser rotation axis LR. By swiveling the supporting frame 384 laser swivel axis S the upright orientation of the laser rotation axis can be varied. The swiveling operation is support and driven by a, in particular combined or separated, Laser Swivel drive & bearing unit 385.

During one full rotation of the mirror 382 the scanning device scans a 2D section lines of the surfaces of objects around the scanner within the field of view. Hereby the position of the mirror defines a section plane, which may be perpendicular to the rotation axis LR. By changing the orientation of the rotation axis LR the section plane is varied. As figures 15a and 16a show.

Figure 15b and 16b each show a simplified scan result of an aircraft located centrally in front of the scanning device. Each 360° rotation of the can be done at various swivel angles / various orientations of rotation axis LR, to enable a three dimensional scan.

Figure 17 shows aircrafts of the same aircraft family, but of different versions within the same family. As apparent, the aircraft differs in side view significantly by the overall length, by the x- position of the doors, wings and engines. Besides the door position in particular the wing position and engine position are important for a safe movement of the PBB. This significance in the difference can be used to determine the version of the aircraft approaching the gate more precisely. As it is not shown in the figure, but can be easily retrieved by public pictures of common aircraft types, the frontal view of the versions within the same family is identical or at least very similar. Consequently, there is an increased likelihood, that the correct aircraft can be validly determined by looking at the aircraft from the side rather than form the front. It is to be noted that scanning an aircraft via laser often does not lead to a clear and unique picture. Even under the usage of modern laser scanners, the result is in a first step a cloud of scan points, which has to be interpreted. The more significant the differences are in the primary shapes, the more reliable results can be generated within a subsequent step in which the scan results are matched with a prestored model.

Based on the previous finding figures 18 and 19 shows an embodiment of a particular usage. Here the aircraft is exemplary located in its final parking position S2 at a selected centerline CS=C2. The orientation between the aircraft correctly parked on the centerline and the stop position is as following. When viewed in top view a line SN between the nose and the scanning device 38 relative to the selected centerline CS and/or the longitudinal axis of the aircraft is at least 35°, in particular at least 45°. Nose means: the most foremost point of the aircrafts fuselage. That leads to a side view scan of the aircraft instead of a frontal view scan as it used conventionally in the prior art. The described significant differences in the versions can be determined more reliable in a situation where the aircraft is scanned more from a side view than from a frontal view. Consequently the method improves the ability to determine the version of the aircraft in addition to the position of the aircraft. A scanning device 38 according to figures 14-16 or any other suitable device may be used.

List of reference signs

1 aircraft

11 front wheel

2 terminal building

20 stand

21 Passenger boarding bridge

22 coordinate system

23 apron area of stand

231, 2311, 23111 range of presented apron area

30 VDGS system

31 aircraft type indication

32 longitudinal information

33 lateral information

34 selected centerline indication

35 stop position indication

36 CPU

37 display

371 electronic visual display / LCD display

372 video sequence presented on display

38 scan device / 3D-scanner

381 Laser Source

382 Laser Mirror

383 Mirror Motor

384 supporting frame

385 Laser Swivel drive & bearing unit

39 database

40 main housing

41 auxiliary housing

42 data connection

43 camera

50 3D model of aircraft surface 60 scan of aircraft

P surface points of scan

dp spatial relation

dx longitudinal offset

dy lateral offset

C1,C2,C3 centerline

S1,S2,S3 stop position on centerline (as part of spatial centerline information)

D 1.D2.D3 direction vector (as part of spatial centerline information) x.y.z spatial coordinates

A yaw angle

R angular range of scanner in top view

Z zoom factor

N aircrafts nose

LS Laser swivel axis

LR Laser rotation axis

LB Laser Beam

SN line through the aircrafts nose and the scanning device

AOS Angle of Scanning direction relative to aircraft orientation