METHOD FOR AUTOMATED DOCKING A PASSENGER BOARDING BRIDGE TO AN AIRCRAFT

Abstract

A method for the automated docking of a passenger boarding bridge to an aircraft parked in a stand includes, determining a target position with respect to a door of the aircraft, to which target position a bridgehead of the passenger boarding bridge is to be moved, and moving the bridgehead to dock with the door of the aircraft based on the determined target position.

Claims

1.-22. (canceled)

23. A method for the automated docking of an airport passenger boarding bridge to an aircraft parked in a stand, the aircraft having a fuselage and a door, to which door a bridgehead of the passenger boarding bridge is to be aligned, the method comprising: determining a target position with respect to the door, to which target position the bridgehead is to be moved; and moving the bridgehead to dock with the door of the aircraft, based on the determined target position.

24. The method of claim 23, further comprising: detecting, in a first phase, an assumed position of the door by using a first detection technology, the assumed position having a first accuracy; and moving the bridgehead in a direction of the assumed position of the door; wherein the step of determining a target position comprises, determining, in a second phase, the target position by using a second detection technology, the target position having a second accuracy, wherein the first detection technology is different from, and is less accurate than, the second detection technology.

25. The method of claim 24, wherein using the first detection technology comprises: determining, by a docking guidance system, a type of aircraft to which the passenger boarding bridge will be docked; and retrieving, from a database, the assumed position of the door based on the determined aircraft type.

26. The method of claim 25, wherein the using the first detection technology further comprises selecting one of a plurality of doors of the aircraft as the door to which the passenger boarding bridge will be docked.

27. The method of claim 23, wherein the stand in which the aircraft is parked can be serviced by at least two passenger boarding bridges, the method further comprising: automatically selecting one of the at least two passenger boarding bridges to dock with the aircraft, based on one or more of the determined aircraft type, or the selected door to which the passenger boarding bridge will be docked; and allocating the target position to the automatically selected passenger boarding bridge for controlling movement of the bridgehead of the selected passenger boarding bridge.

28. The method of claim 23, wherein the step of determining a target position comprises optically scanning the door with a main scanning device disposed on the passenger boarding bridge.

29. The method of claim 28, wherein the step of determining a target position comprises: optically scanning the door with the main scanning device to, one or more of, generate a scanned door contour, identify one or more of a painted contour marking painted on or adjacent to the door, and/or identify a u-shaped marking painted below the door; analyzing at least one of the scanned door contour or the painted contour marking to determine a longitudinal coordinate and a transverse coordinate of the target position; and analyzing a position of the scanned u-shaped marking to determine a height coordinate of the target position.

30. The method of claim 24, further comprising: obtaining, in the second phase, a digital model of the door by one or more of, generating the digital model by optically scanning the door with a main scanning device disposed on the passenger boarding bridge, or retrieving from a database a stored copy of the digital model of the door.

31. The method of claim 30, further comprising: moving the bridgehead, in a third phase, close enough to the door such that the door is only partially in a field of view of the main scanning device and the target position is outside the field of view of the main scanning device; monitoring with the main scanning device an auxiliary position of the door; and calculating the location of the target position based on the auxiliary position and a spatial relationship defined in the digital model between the target position and the auxiliary position.

32. The method of claim 23, wherein the step of determining the target position is performed by a main scanning device located below a roof of the bridgehead at least 2.1 meters above the bridgehead floor, rearwardly offset at least 0.5 m from the approaching edge of the bridgehead, and between side walls of the bridgehead.

33. The method of claim 30, further comprising: moving the bridgehead, in a third phase, close enough to the door such that the door is only partially in a field of view of the main scanning device and the target position is outside the field of view of the main scanning device; and scanning the door with an auxiliary scanning device to determine the target position.

34. The method of claim 33, further comprising: scanning the door with both the main scanning device and the auxiliary scanning device during the second phase when the target position is within the fields of view of both the main scanning device and the auxiliary scanning device, to generate separate digital models of the door by each of the main scanning device and auxiliary scanning device; and comparing the digital models generated by each of the main scanning device and the auxiliary scanning device to each other, to check that both the main scanning device and the auxiliary scanning device are functioning properly.

35. The method of claim 24, further comprising: establishing a trajectory that defines how the bridgehead will be moved to align the bridgehead with the target position, the trajectory comprising a path along which the bridgehead will travel and a course of orientations of the bridgehead; and moving the bridgehead along the established trajectory.

36. The method of claim 35, wherein while moving the bridgehead along the established trajectory, the method further comprises: continuously determining the target position to identify any deviation in a location of the target position from a previously determined target position; reviewing the trajectory based on the continuously determined target position; and executing program instructions to adjust the trajectory of the bridgehead when deviation in a location of the target position from a previously determined target position is identified and/or initiate a safety mode if the deviation from the previously determined target position exceeds a predefined threshold value.

37. The method of claim 35, further comprising: observing the apron with respect to an obstacle; detecting a position of the obstacle; assessing the relevance of the obstacle by comparing the position of the obstacle with the trajectory; issuing the PBB into a safety mode based on the assessed relevance.

38. The method of claim 35, wherein the step of moving the bridgehead along the established trajectory includes, in a third phase, aligning an approaching edge of the bridgehead, when viewed in a top down view, parallel to the door; and moving the bridgehead to its final height position.

39. The method of claim 35, wherein the step of moving the bridgehead along the established trajectory includes, moving the bridgehead at a movement speed that depends on a distance of the bridgehead from the door, wherein the movement speed decreases as the distance between the bridgehead and the door decreases.

40. The method of claim 24, wherein the stand is a MARS stand having a plurality of separate centerlines painted on the ground to indicate the possible parking positions of the aircraft for the passenger boarding bridge, wherein the detection of the assumed position or the determination of the target position is based in part on information as to which of the plurality of centerlines at which the aircraft is parked.

41. The method of claim 33, further comprising: calibrating a camera of one or more of the main scanning device or auxiliary scanning device before docking the bridgehead to the door, by bringing a calibration tag located at a fixed location on the bridgehead within a field of view of the camera.

42. The method of claim 38, further comprising: after the step of aligning the approaching edge of the bridgehead parallel to the door, validating that the bridgehead is properly aligned with the door.

Description

[0047] The invention is explained in more detail by means of the figure, the figures show:

[0048] FIG. 1 a second phase of the automated docking procedure in top view;

[0049] FIG. 2 a third phase of the automated docking procedure in top view;

[0050] FIG. 3 a fourth phase of the automated docking procedure in top view;

[0051] FIG. 4 a section through the illustration of FIG. 3 along the section line V-V;

[0052] FIG. 5 a section through the illustration of FIG. 4 along the section line VI-VI;

[0053] FIG. 7 three exemplary embodiments of the door contour of the plane;

[0054] FIG. 8 definitions of coordinates and reference points with respect to the aircraft door;

[0055] FIG. 9 a graphical representation of a three-dimensional door model;

[0056] FIG. 10 the PBB when view in direction of arrow X in FIG. 1;

[0057] FIG. 11 diagrams of the trajectory;

[0058] FIG. 12 definitions of the coordinate system;

[0059] FIG. 13 the section of FIG. 5 showing a calibration tag;

[0060] FIG. 14 a speed profile during docking;

[0061] FIG. 15 the alignment of the door in the open and closed state and the bridgehead;

[0062] FIG. 16 passenger boarding bridges at different parking positions in a MARS stand in top view.

[0063] Within the scope of the present application a coordinate system is defined, which is relevant for the docking procedure (FIG. 12). Therein the direction x indicates the longitudinal direction of the fuselage 2 in the area of the door 3 to be docked. The direction y indicates the transverse direction perpendicular to the fuselage in the area of the door. The difference between FIGS. 12a and 12b indicates, that the x- and y-direction may slightly differ from the airplane coordinate system in particular where the door 3 is located in the nose of the aircraft (FIG. 12b). The direction z indicates the height direction perpendicular to directions x and y.

[0064] At first reference is made to FIGS. 7 and 8, explaining some basic definitions with are important for the present invention.

[0065] FIG. 7 shows different configurations of the appearance of an aircraft door 3 within an aircraft fuselage 2. The door 3 is surrounded by a door contour 31, which is characterized by a small gap between the door and the fuselage 2. The door contour 31 comprises four sections, namely the door contour upper 31U, the door contour lower 31L (also: called door sill 31L), and two door contour sides 31S (one on the left side and one of the right side of the door 3).

[0066] A ribbon is applied with paint on the fuselage 2 and/or the door 3, which highlights the door contour 31. This ribbon is called painted contour mark (PCM) 32. As the different configurations of FIG. 7 show, the PCM 32 does not necessarily match exactly with the door contour 31, nevertheless the PCM 32 gives an indication of the door contour shape and position.

[0067] For example in the embodiment of FIG. 7a) the PCM 32 may be painted within the door contour 31, here without touching the door contour 31 at all. In another embodiment as shown in FIG. 7b, the PCM 32 may be painted on the door contour, so that the door sill is in overlapping condition with the PCM 32. In still another embodiment as shown in FIG. 7c, the PCM 32 may be painted in the upper area outside of the door contour 31, the lower part of the PCM 32 is painted within the door contour 31. Nevertheless in all embodiments the PCM is intended to highlight the approximate position of the door contour 31. In the longitudinal direction x center of the PCM 32 may be centered to the center of the door sill 31.

[0068] In addition to the PCM 32 a u-shaped mark 33 is provided at the lower part of the aircraft door 3. The upper line of the u-shaped mark 33 is collinear with the door sill 31L as shown in all three embodiments of FIG. 7. The u-shaped marking may be painted to the fuselage or may be a visible protrusion of the fuselage.

[0069] It is mandatory for aircraft manufacturers to add the PCM 32 and the u-shaped mark 33; for details are described in technical manuals and the federal US regulation 14 CFR 25.811-Emergency exit marking.

[0070] FIG. 8 shows the door contour 31 without the PCM 32 and the u-shaped marking 33.

[0071] Herein first and second lower reference points T1, T2 are shown, which may be used as a target position within the present invention. Each lower reference point T1 T2 is in particular [0072] located on the surface of the fuselage 2; [0073] is located on a first horizontal plane Z1 in the level of the door sill 31L; [0074] is located on a first vertical plane X1 or on a second vertical plane X2. Each of the vertical plane X1 and X2 is parallel to the height direction z and the transversal direction y and is aligned with the most forward point P1 (for X1)/most reward point P2 (for X2) (along longitudinal direction x) of the door contour 31.

[0075] Respectively there are third and fourth upper reference points T3, T4 shown, which are of interest for the present invention. Each upper reference point T3 T4 in particular [0076] is located on the surface of the fuselage 2; [0077] located on a second horizontal plane Z3 in the level of the door contour upper 31U; [0078] is located on a first vertical plane X1 or on a second vertical plane X2. Each of the vertical plane X1 and X2 is parallel to the height direction z and the transversal direction y and is aligned with the most forward point P1 (for X1)/most reward point P2 (for X2) (along longitudinal direction x).

[0079] If possible, the foremost/rearmost point P1, P2 which are used for defining planes X1 and X2, are the foremost/rearmost points of the door contour 31 as shown in FIG. 8.

[0080] If the contour 31 itself cannot be extracted clearly it is also sufficient that the most foremost/rearmost points of the PCM 32 are used as the most foremost/rearmost points P1, P2 for defining the planes X1, X2. For detecting the position of the door in longitudinal direction x it is merely important to have positional information which is roughly centered with the door. Each of the reference points Ti has the coordinates xti, yti, zti (for i=1, 2, 3 or 4).

[0081] As can be seen in the different illustrations the PCM in different embodiments the PCM does not match with the door contour 31; however in any case the PCM 32 is sufficiently centered in longitudinal direction with the door contour 31.

[0082] FIG. 1 shows an aircraft 1, which is located at a parking position on the apron of an airport. A passenger boarding bridge 10 is positioned in a parking position. In an embodiment the aircraft 1 is detected by a visual docking guidance system (VDGS) 94. The VDGS 94 determines the type of the aircraft 1 and information about the position of the aircraft 1. A suitable VDGS 94 is disclosed in EP 2 660 152 A2, herein called docking system.

[0083] In this example the VDGS 94 recognizes, that the aircraft 1 is an Airbus A320-200, and should be located on a predetermined parking position. In addition in a database 91, in particular connected to the flight control center, information about the type and identification of the next aircraft expected at the gate may be stored. In fact the aircraft parking position will slightly deviate from the exact predetermined parking position, what can be detected by certain types of VDGS 94. The VDGS 94 is connected to the database 91, the database 91 may comprise structural information of the aircraft, in particular the relative position of the door 3 to be docked within the aircraft coordinate system. Based on the available information with respect to the position of the plane 1 at the apron and the relative door position within the aircraft 1 an assumed position 8 of the aircraft door 3 can be calculated. Here the assumed position is an area 8, in which the position of the aircraft door may be located.

[0084] Alternatively or in combination the database 91 may comprise immediate positional information of the assumed door position, if the type and/or identification of the next arriving aircraft is stored, since each aircraft of the same type has to be parked at the same parking position and comprise identical located doors. The database may also comprise individual information of which door is to be docked. This in particular of interest for wide-body aircrafts, which comprise two or more left doors in front of the wings, which may be considered for being docked by a standard (not overwing) PBB. Optional details are described later with reference to FIG. 16.

[0085] The PBB 10 comprises, as usual, a tunnel 11 which is on the one end connected in a conventional manner to a rotunda located at the airport building (not shown). On the other end the PBB comprises a bridgehead 13, which is to be brought into alignment with the aircraft door 3, so that passengers can leave the aircraft 1 via the door 3 and the tunnel 11, in direction 21 to the airport terminal building.

[0086] Conventional drive means 12 are provided as to adjust the position of the bridgehead 13 by adapting the length and orientation of the tunnel 11. A conventional lift system (not shown) may be provided to adjust the height position of the bridgehead 13. Additionally the relative angular orientation between the bridgehead 13 and the tunnel 11 can be adapted, since a pivotable joint between the bridgehead 13 and the tunnel 11, in particular a round cabin 22, is provided between the bridgehead 13 and the tunnel 11.

[0087] The operation of the drive means 12 is controlled by a control unit 93 of the PBB 10. The control unit 93, the VDGS 94, the database 91 and a data connection 92, connecting the aforementioned components are part of a control arrangement 90.

[0088] At the bridgehead 13 a main camera 50 is provided which is used for automatic docking of the bridgehead 13 to the door 3. The main camera 50 has a field of view 51. In situation A the passenger boarding bridge 10 is located in parking position. Here the door 3 is not located in the field of view of the main camera 50. Hence the camera based docking system cannot operate yet. Consequently, at first a prepositioning step has to be performed to bring the main camera 50 into a position, in which the door 3 is in the field of view 51 of the main camera 50.

[0089] During or before prepositioning a positional information is obtained with the help from the database 91, in particular in combination with the VDGS 94. This positional information is used for determining an assumed position 8 of the door 3. Based on that available information the control unit 93 initiates a first movement of the bridgehead 13 into a condition, where door 3 is in the field of view 51 of the main camera 50 (situation B in FIG. 2). Now the camera based docking procedure can start. In another embodiment the prepositioning can be obtained manually by an operator.

[0090] In a subsequent phase B-C, which is the time between situation B (FIG. 2) and situation C (FIG. 3), the bridgehead 13 is further moved into the direction of the door 3. Thereby a distanced between an approaching edge 20 of the bridgehead floor 17 (see FIG. 5a) and the door 3 is reduced. During this phase B-C the approaching edge 20 is still spaced apart from the fuselage 2. During phase B-C the bridgehead 13 is put into an orientation in which the approaching edge 20 is aligned parallel to the door sill 31L.

[0091] FIG. 5 shows details of situation C. FIG. 5a shows a cross-section through aircraft 1 and the PBB 10 along section line V-V in FIG. 3. In general the approaching edge 20 may be located at a floor bumper 18 on the floor 17 of the bridgehead 13.

[0092] For a proper docking it is essential, that the approaching edge 20 is properly aligned in parallel to the door sill 31L. Additionally the approaching edge should be aligned in a predetermined way in the longitudinal direction x; in particular the bridgehead 13 may be centered to the center of door gap 31 or may be aligned slightly offset to the center of the door gap 31 (to enable an opening of the door). A large door may collide with the side wall of the canopy, if the bridgehead is centered exactly. For aligning the bridgehead 13 in the longitudinal direction x the first reference point T1 and the second reference point T2 are used.

[0093] FIG. 5b shows the picture 52 obtained by the main camera 50 during phase B-C; all four reference points T1, T2, T3, T4 are located within the field of view 51. With the help of the first reference points T1, T2 the door sill 31L can be located. Consequently the approaching edge 20 is to be aligned with the first and second reference points T1, T2 during docking. Consequently the first and second reference points T1, T2 together is considered as a target position T1, T2 for the automatic docking procedure.

[0094] During phase B-C the main camera 50 is used for scanning the door 3. A result of that scanning is the creation of a digital three-dimensional model 3d of the door 3, which is shown in FIG. 9. In this specific embodiment the dimensional door model 3d comprises three-dimensional surface data of the door.

[0095] In another embodiment a plurality of models 3d is already prepared and stored in a database 91. Here to each of a plurality of aircraft types an individual door model 3d is allocated. As discussed before, the VDGS 94 may be used for determining the aircraft type or the aircraft type expected may be stored in the database 91. The database 91 may be asked for providing the prestored model 3d associated to the determined aircraft type. Prestored means, that the door model 3d is already available in a database before the docking procedure begins and the door model 3d can be retrieved from the database 91 during docking. This may be used for determining the model 3d instead of creating a door model 3d each time during each docking process. Alternatively a prestored three-dimensional model 31 and a three-dimensional model 3d can be used together to verifying the aircraft type or to improve the quality of a created model 3d.

[0096] The obtained coordinates of the reference points T1-T4 are shown in FIG. 5c, left column. Already the group of the four coordinates can be considered as a three-dimensional model 3d of the door. With the help of the obtained model a spatial relationship between the obtained reference points can be determined, in particular calculated vectors D13, D24 (see also FIG. 9) reflect a spatial relationship between third and first reference points T3,T1/fourth and second reference points T4,T2. FIG. 5c, right column, shows these determined spatial relationships, in particular vectors D13, D24, which can also be or can become part of a determined three-dimensional model 3d of the door 3.

[0097] FIG. 6 shows details of situation D. FIG. 6a shows a cross-section through aircraft 1 and the PBB 10 along section line VI-VI in FIG. 4. Subsequently during phase C-D (see FIGS. 4 and 6) the bridgehead 13 is further moved in direction of the door 3, thereby maintaining the achieved parallel alignment of situation C until the distance d become smaller than a predetermined maximum gap value, in particular less than 50mm. FIG. 6b shows the picture 52 obtained by the main camera during phase D; the lower reference points T1, T2 are not located within the field of view 51 anymore.

[0098] The result to be achieved in situation D is to properly align the approaching edge 20 with the door sill 31L. But since the fuselage itself is more and more covering the door sill 31L during at a certain situation in phase C-D it cannot be assured that the lower reference points T1 and T2 or any other point on the door sill 31L can be seen by the a camera reliably. Here situation C1 is a point in time, when reference points T1, T2 get out field of the view 51. FIG. 6b shows the picture 52 obtained any time in phase C1-D.

[0099] It is to be noted that properly aligned does not mean, that the approaching edge is in an exact overlapping condition with the door sill 31L. Rather a proper alignment may require a safety gap between the approaching edge and the fuselage of about 5 cm and the floor of the bridgehead should be aligned slightly below the level of the door sill (about 15 cm), so that a safety shoe can be placed between the door and the bridgehead floor 17.

[0100] During phase B-C1 the upper reference points T3, T4 and the lower reference points T1, T2 are within the field of view 51 of the main camera 50. The main camera 50 is a stereo camera, through which the relative positions of the reference points to the camera position can be calculated. This is done by usual stereoscopic analysis of the obtained pictures using available picture recognition algorithm.

[0101] In case the picture recognition algorithm does not provide a valid position of the reference points, the user can be prompted to assist e.g. by mouse clicking on to the illustration of the corners of the door, which are presented to the user on a screen.

[0102] Based on that the spatial coordinates (xt1, yt1, zt1), (xt2, yt2, zt2), (xt3, yt3, zt3), (xt4, yt4, zt4) of all four reference points T1, T2, T3, T4 are calculated (see box in FIG. 5c). The group of the coordinates of these four reference points can be considered as a basic digital three-dimensional model 3d of the door 3. In an advanced embodiment the three-dimensional door model 3d can comprise extensive data representing the surface of the door as shown in FIG. 9.

[0103] Based on the obtained model 3d a differential relationship e.g in form of the vectors

[0104] D13, D24 can be calculated. The first differential vector D13 constitutes the spatial difference between the third reference point T3 and the first reference point Tl. The second differential vector D24 constitutes the spatial difference between the fourth reference point T4 and the second reference point T2.

[0105] In phase C1-D (C1 is a situation after situation C and before situation D), the first and second reference points T1, T2 are not visible to the main camera 50. However the third and fourth reference points T3, T4 are still visible and their position can be determined by the main camera. With the help of the model 3d, the coordinates of the first and second reference points T1, T2 can be obtained, in particular by calculating (see right column in box of FIG. 6c), even if these first and second reference points T1, T2 are not visible to the main camera 50 anymore.

[0106] It is an advantageous that the door 3 is as long as possible visible by the main camera 50. Therefore the position of the main camera 50 is an important aspect. It has been found out that for the function of the present application it is advantageous, that the main camera is positioned [0107] below the roof 19 of the bridgehead 13 (inluding canpoy roof section), [0108] at a level at least 2.1 meters above the bridgehead floor 17, [0109] at least offset in rearward direction (see dimensions in FIG. 5) of at least 0.5 m. This position enables that the door contour upper 31 U is visible over the entire docking process at a distance of at least 0.5 meters, which is suitable to calculate the relative of the auxiliary points T3, T4 relative to the main camera 50.

[0110] Alternatively or additionally an auxiliary camera 55 may be used for continuing determining the target position T1, T2 during the phase C1-D, when the target position is not in the field of view of the main camera 50. Exemplary the position of the auxiliary camera 50 is shown in FIG. 6a. The auxiliary camera 55 is located at a lower height position than main camera 50. Consequently the first and second reference points are in the field of view of the auxiliary camera, even when these points are out of the field of view 51 of the main camera 50. Also the auxiliary camera 55 is in particular protected from any interaction with passengers, which is more likely at this lowered position.

[0111] As can be seen in in FIG. 6a there is likelihood, that the first and second reference points T1, T2 may be covered by the protruding floor bumper 18, in case the PBB is too much elevated. Therefore the position of the auxiliary camera 55 is disadvantageous especially in the early phases B-C of the camera based docking procedure.

[0112] However the lowered position of the auxiliary camera 55 position has the increased risk to loose the view of the complete door earlier than the upper position of the main camera 50. To have the door as long as possible within the field of view of one single camera increases the scanning results and in particular the creation of the three-dimensional model 3d of the door. Consequently the upper position of camera 50 has advantages although the target position will be lost in the field of view 51. So, a critical distance d, at which the upper main camera 50 loses the parts of the complete door from its field of view is roughly about 1 m; a critical distance d, at which the lower auxiliary camera 55 loses the parts of the complete door from its field of view is roughly about 2 m. So, for establishing the model 3d, the upper camera is more advantageous.

[0113] As long as both cameras can see the target position T1, T2, the auxiliary camera 55 can be calibrated with the scan results of the main camera 50.

[0114] FIG. 10 shows the PBB when view from a direction of the door 3 at situation C. The main camera 50 is preferably positioned at a height of at least 2.1 m above the floor 18a and below the roof 19 and inside of side wall 23. The auxiliary camera 55 is preferably positioned at a height of at maximum of 1.8 m, preferably at maximum of 1.5 m, above the floor 18, below the roof 19 and inside of side wall 23.

[0115] FIGS. 2, 3, 4 shows a trajectory 60, which is the basis for the movement of the bridgehead 13. Details of the trajectory are shown in FIG. 11 (FIG. 11 a is a top view of the trajectory 60, FIG. 11 b is a side view of the trajectory 60). The trajectory 60 comprises a path 61. The path 61 represents a number of positions of a PBB component, which is relevant to the bridgeheads position and passing the trajectory during automatic docking. This positions may be the center of the drive means 12. Here in accordance with the trajectory 60 the bridgehead performs a movement in x, y and z direction, leading from situation B via situation C to situation D, in which the approaching edge 20 is aligned with first and second reference points T1, T2.

[0116] The trajectory 60 comprises also a course 62 of orientation 62b-d. Here the orientations 62b-d are vectors defining the direction in which the bridgehead 13 is pointing during the situations B, C and D. In the final docked situation D it is essential, that the approaching edge is oriented in parallel to the door sill 31 L. That means that in situation D the vector 62d is perpendicular to fuselage 2 in the area of the door 3. Note, that the fuselage may be curved, what is neglected in this description for keeping the complexity low.

[0117] As obvious from FIG. 11 the trajectory is calculated in a manner, that in situation C the bridgehead as already reached its finals position in height direction z and longitudinal direction x. So, starting from situation C the bridgehead merely performs a movement in y-direction, which is perpendicular to the fuselage 2 in the door area, which reduces risks of damaging the fuselage.

[0118] The trajectory 60 can also be used for assessing an obstacle collision between the PBB and an obstacle. Generally an obstacle may be detected comparing a first image with a second image of any additional camera or another sensor, which can be attached a in the area of the drive 12. The first image may be a prestored image showing the apron area without any obstacle. The second image is an actual image, showing the current situation of the apron. With the help of picture recognition differences between the two images can be determined. Any object, which is present in the second image, but which is not present in the first image, may be considered as an obstacle.

[0119] But not all obstacle in the apron present a problem. Within the scope of the invention, only such obstacles may present a problem, which lie in the area of the trajectory. FIG. 11 a indicates a plan view of the trajectory 60. Herein the position of first and second obstacles 63, 64 is depicted.

[0120] The first obstacle 63 has a plan view distance to the trajectory of d63, which larger than a required minimum clearance distance c. Consequently first obstacle 63 is not considered as problematic. The second obstacle 64 has a plan view distance to the trajectory of d64, which is smaller than a required minimum clearance distance c. Consequently second obstacle 64 is considered as problematic. The presence of the second obstacle 64 will induce the control unit to switch into a safety mode. In the safety mode, the movement of the PBB may be stopped or at least a warning signal may be issued. It is possible that there are distinct safety mode, to which different clearance distances are allocated.

[0121] Due to vibrations and/or other environmental influences the calibration status of the camera may be invalid during operation of the bridge. Therefore the system comprises an auto-calibration procedure, which is described with reference to FIG. 13.

[0122] A calibration tag 53 is provided at a defined position within the field of view 51, 56 of the camera to be calibrated, in particular of the main camera 50 and/or of the auxiliary camera 55. The tag 53 may be fixed with a tag fixture 54 to the bridgehead 13. The fixture may be a separate part as shown in FIG. 13. Alternatively the floor 17 or a cabin side wall 23 (see FIG. 10) of the bridgehead 13 can be part of the fixture or may constitute the fixture. E.g. the tag 53 may be painted on the floor 17 or it may be a significant part of the bridgehead 13.

[0123] The position of the calibration tag 53 relative to the position of the camera 50, 55 to be calibrated is prestored. So, in a calibration step before docking the camera is calibrated. Hereby the camera performs a step of detecting the relative position of the tag by image recognition. The camera is then calibrated by comparing the detected position with the prestored position.

[0124] FIG. 14 depicts the speed profile during docking. V13 represent the speed of the bridgehead in plan view, in x- and y-direction. During prepositioning (phase A-B) the speed V13 may be max. 0.5 m/s. During final phase of docking (C-D), in particular when the distanced is smaller than 1 meter, the speed V13 may be max. 0.1 m/s; in particular when the distance is smaller than 0.5 m the speed V13 may be max. 0.05 m/s.

[0125] The vertical speed in height direction z (not shown in FIG. 14) may be reduced to a max of 0.1 m/s during phase A-C. In the final phase of docking (distance d<1 m) the vertical speed may be reduced to max 0.05 m/s.

[0126] FIG. 15 shows the aircraft door in the closed condition (door 3a) and in the open condition (door 3b). In both conditions, the door 3 is overlapping the bridgehead 13 in longitudinal direction x. Since the door is most cases opened not before the docking is completed, a swing range 3s of the door from the closed condition in the open condition is completely in within the side walls 23 the bridgehead 13.

[0127] In an embodiment to validate that the bridgehead is properly docked a validation tag 57 is attached provided e.g. at the floor 17 of the bridgehead 13. The validation tag 57 may be an optical mark, which can be detected and located by the main camera 50. The camera checks the alignment in particular in longitudinal direction x between the validation tag 57 and a hinged side 31 of the door 3 (in closed condition). The hinged side 31 of the door 3 is where the door hinge and axis of door swing may be located. Here the hinge side is the left side, so when viewed from the bridgehead, the door swings to the left side. The hinged side 31 may be optically detected with the help of the contour side 3S or of an area of the PCM marking 32 (see FIG. 7). For positive validation there may be a tolerance in the alignment between the validation tag 57 and the hinge side 31 of about 20 cm.

[0128] The calibration tag 57 and the calibration tag 53 can be the same tag.

[0129] Within the scope of the present invention a main camera is described which is enabled to detect e.g. the location of the target. From this formulation is becomes obvious, that the term camera is used also for describing a more complex arrangement having, in addition to purely a photo sensor, huge image analyzing capabilities; this camera may be split into separate devices and may comprise a computer.

[0130] The invention provides a method which does not require any coding at the fuselage of the aircraft, which contains a coded information about the location of the door, e.g. a QR code or a RFID tag. Thus the invention does not require any preparation performed at the aircraft. Thus any individual aircraft arriving at the PBB can be processed with the inventive method.

[0131] FIG. 16 shows a gate having a Multiple Apron Ramp System (MARS) stand 25. Here three centerlines 24a-c are provided, which indicate the parking positions for different aircrafts 1a-c. The stand comprises two passenger boarding bridges 10a, 10b, which can connect the aircrafts with a terminal building 23.

[0132] FIG. 16a shows a docking situation when a first aircraft 1 a is to be docked: The first aircraft 1a is a wide body aircraft, e.g. an Airbus A350. Because of the size if a wide body aircraft is located at the stand no other aircraft can be located at said stand at the same time. The two boarding bridges 10a, 10b are shown in a preposition. The first passenger boarding bridge 10a will be docked to the first door, the second passenger boarding bridge 10b will be docked to the second door.

[0133] FIG. 16b shows another docking situation when a second lb and a third aircraft lc is to be docked. Both aircrafts are single aisle aircraft, e.g. an Airbus A320 or smaller, which require less space than the wide body aircraft of FIG. 9a, so that two of them can be located at the same time at said stand. The two boarding bridges 10a, 10b are shown in their preposition. The first passenger boarding bridge 10a will be docked to aircraft 1b, the second passenger boarding bridge 10b will be docked to aircraft 1c.

[0134] In particular the preposition is/the prepositions are a selected from a number of predefined prepositions based on the type of aircraft and/or based on the parking position of the aircraft. During docking the it is determined, on which centerline of the MRS stand the aircraft is parked; based on the determined centerline the target position cab be determined in a rough way, in particular by retrieving an appropriate positional information from a database.

[0135] The MARS stand comprises two or more PBBs. Before docking it needs to be decided, which of the plurality of PBBS are to be docket. The decision can be made automatically thereby using predefined allocation or selection rules which can considere the type of aircraft to be docked, the specific centerline on which the aircraft is located, and/or a selection of the door which is to be connected by a PBB.

LIST OF REFERENCE SIGNS

[0136] 1 aircraft

[0137] 2 aircraft fuselage

[0138] 3 aircraft door

[0139] 3a closed door

[0140] 3b open door

[0141] 3d door model

[0142] 3l left side of door

[0143] 3h door hinge

[0144] 3s door swing range

[0145] 4 reference points

[0146] 5 apron ground

[0147] 6 side window

[0148] 7 cockpit window

[0149] 8 assumed area of aircraft door

[0150] 10 Passenger boarding bridge

[0151] 11 tunnel

[0152] 12 drive means

[0153] 13 bridgehead

[0154] 14 interior of bridgehead

[0155] 15 canopy

[0156] 16 canopy bumper

[0157] 17 floor

[0158] 18 floor bumper

[0159] 19 cabin roof

[0160] 20 approaching edge

[0161] 21 direction to airport terminal building

[0162] 22 round cabin

[0163] 23 cabin side wall

[0164] 24 centerline

[0165] 25 MARS stand

[0166] 31 door contour

[0167] 31U door contour upper

[0168] 31L door contour lower

[0169] 31S door contour side

[0170] 32 contour mark

[0171] 33 U-shaped mark

[0172] 50 main camera

[0173] 51 field of view of main camera

[0174] 52 picture

[0175] 53 calibration tag

[0176] 54 tag fixture

[0177] 55 auxiliary camera

[0178] 56 field of view of auxiliary camera

[0179] 57 validation tag

[0180] 60 trajectory

[0181] 61 path

[0182] 62 course of orientation

[0183] 62b-d orientation vector

[0184] 63 first obstacle

[0185] 64 second obstacle

[0186] 90 control arrangement

[0187] 91 database

[0188] 92 data connection

[0189] 93 control unit

[0190] 94 VDGS

[0191] x longitudinal direction

[0192] y transverse direction

[0193] z height dorection

[0194] Z horizontal plane (within aircraft)

[0195] X vertical plane (within aircraft)

[0196] T1,T2 target position

[0197] T3,T4 auxiliary position

[0198] s rearward offset of main camera 50 behind approaching edge

[0199] tx,ty,tz coordinates of the position of the reference points

[0200] h height above ground

[0201] d distance between approaching edge and fuselage