Communications: electrical – Aircraft alarm or indicating systems – Docking guidance
Reexamination Certificate
2002-12-17
2004-07-13
Swarthout, Brent A. (Department: 2636)
Communications: electrical
Aircraft alarm or indicating systems
Docking guidance
C244S11400R, C382S104000
Reexamination Certificate
active
06762694
ABSTRACT:
FIELD OF INVENTION
The present invention relates to a centreline identification in a docking guidance system, and in particular to a centreline configuration in a docking guidance system which allows for a quick adequate handling of the centreline configuration.
BACKGROUND ART
Recently, there may be observed a significant increase in the amount of air traffic including take-offs, landings and other aircraft ground traffic. Further, also an increased number of ground support vehicles are required to handle cargo, passengers, and to provide catering services as well as maintenance and support of aircraft at airports. With this substantial increase in ground traffic, there arises a need of greater control and safety in the docking and identification of aircraft on an airfield. Heretofore, visual docking guidance systems, also referred to as VDGS systems, are used to achieve a safe and precise guidance during the docking of aircraft to the related aircraft stand. Important to note that the information that the airplane pilot receives from the visual docking guidance system must be so accurate that the aircraft is guided to a correct stop position with least possible risk of colliding with an obstacle on the apron.
FIG. 1
shows a typical environment for the application of such docking guidance systems. Typically, an aircraft
10
approaches a terminal building
12
which is located adjacent to the airfield. For a precise guidance of the aircraft
10
to an aircraft stand
16
—which may also be located out on the apron when passengers are transported by bus—there is provided a centreline
14
. This centreline
14
comprises painted stop positions
18
for the different aircraft types the aircraft stand
16
is intended for, and sometimes a painted stand ID. Alternatively, the stand ID may be given on a sign placed on a wall of a terminal building. In the vicinity of the aircraft stand, there is provided a tracking system
22
that operatively displays guidance information at a display
24
to the pilot of the aircraft
10
.
In more detail, the tracking system
22
shown in
FIG. 1
provides a location of the aircraft
10
, a verification of the identity of the aircraft and a tracking of the aircraft to the aircraft stand
16
. As soon as the aircraft
10
has landed on the airfield, the tracking system
22
is informed by a control tower
28
that an aircraft is approaching the aircraft stand
16
and also which type of aircraft (e.g., B747) is expected.
The tracking system
22
then continuously scans the apron in front of the aircraft stand
16
, until it locates the aircraft
10
and verifies that the type is the correct one. Subsequently, the tracking system
22
tracks the aircraft
10
to the stop position
18
and also the lateral position with respect to the centreline
14
to the pilot of the aircraft
10
.
The distance and the lateral position are displayed at the display
24
allowing the pilot of the aircraft to correct the position of the aircraft while approaching the aircraft stand
16
.
Once the aircraft
10
has reached its stop position
18
, this is also indicated on the display
24
so that the pilot may stop the aircraft. Once the aircraft
10
comes to a rest, it is therefore accurately aligned with the aircraft stand
16
with minimum requirement of an adjustment of stand facilities relative to the aircraft by ground staff.
Typically, the centreline
14
shown in
FIG. 1
is a yellow line painted on the apron leading to the aircraft stand
16
. The centreline
14
is laid out such that the risk of collision during manoeuvring of the aircraft
10
is minimized. As the pilot of the aircraft
10
has a limited field of view, he may not see the centreline
14
during the approach of the aircraft
10
to the stop position
18
. He may therefore be completely dependent on the guidance given by the visual docking guidance system. For this reason the accuracy with which the visual docking guidance system may guide the aircraft
10
along the centreline
14
is safety critical.
When the visual docking guidance system
22
,
24
is installed at the aircraft stand
16
parameters defining the location of the centreline
14
relative to the visual docking guidance system
22
,
24
must be adjusted or, in other words, configured and/or calibrated for this particular aircraft stand
16
.
The location of the centreline
14
is defined through angle and distance to so-called centreline definition points on the centreline
14
related to the position of the tracking system. These centreline definition points are defined by the operator of the visual docking guidance system to achieve a correct modelling of the layout, course and topology of the centreline.
When the centreline is straight it is sufficient to define two centreline definition points, i.e., well-separated points on the centreline
14
. To the contrary, when the centreline
14
is curved, horizontally and/or vertically, it is necessary to define a plurality of centreline definition points.
FIG. 2
shows in more detail an approach to achieve this functionality through a calibration picture with distance indication using different grades of different colours for increased distance from the aircraft stand.
The example shown in
FIG. 2
is related to a visual docking guidance system that is based, e.g., on a laser range finder generating a laser beam that is directed along different directions by a scanning mechanism in the visual docking guidance system.
Here, the position of each point in front of the visual docking guidance system is defined through two angles &agr;, &bgr;, the first angle &agr; characterizing a vertical inclination towards a horizontal straight plane, the second angle &bgr; being defined with respect to a vertical plane, e.g., running through the tracking system straight out on the apron. Further, a third value d characterizes the distance between the tracking system
22
and the point.
From the above it should be clear that the visual docking guidance system must be configured either after a new installation or after maintenance if there is a probability that the reference direction of the scanning mechanism has been effected. Further as the function of the visual docking guidance system
22
,
24
is safety critical it is important that the configuration of the centreline is achieved with sufficient accuracy.
As shown in the lower part of
FIG. 2
, using such a representation of each scanned point on the apron with respect to the tracking system
22
of the visual guidance system there may be derived an echo picture—equivalently referred to as centerline identification picture or calibration picture in the following—reflecting the position of each scanned point with respect to the tracking system
22
. This picture may be displayed on a computer screen, e.g., using different colours.
In particular, different distance ranges
28
,
30
,
32
in front of the aircraft stand
16
of the terminal are illustrated through, e.g., different colours or shades on a display used during configuration of the visual guidance system
22
,
24
. Therefore, a three-dimensional echo picture is created through scanning the area in front of the aircraft stand
16
. In this echo picture the third dimension, i.e. the distances to objects or scanned points in front of the visual docking guidance system, are represented through different gray shades or different colours, as outlined above.
FIG. 3
shows the calibration picture according to
FIG. 2
when a reflecting reference object
34
is placed in front of the aircraft stand on the apron.
As shown in
FIG. 3
, the reflecting object
34
, typically a big plate, is placed at different points on the centreline
14
for definition of corresponding centreline definition points. Each placement of the reflecting object
34
is visually identified in the centreline identification picture as shown in
FIG. 3
, and the midpoint
36
fixed at the lower edge of the reference object
34
may be referred to for definition of centreline definition points. Measured angles and dist
Blank Rome LLP
Safegate International AB
Swarthout Brent A.
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