Communications: electrical – Aircraft alarm or indicating systems – Potential collision with other aircraft
Reexamination Certificate
2001-01-12
2003-05-13
Wu, Daniel J. (Department: 2632)
Communications: electrical
Aircraft alarm or indicating systems
Potential collision with other aircraft
C340S968000, C340S958000, C340S903000, C340S942000, C340S602000, C340S601000, C244S11400R
Reexamination Certificate
active
06563432
ABSTRACT:
FIELD OF THE INVENTION
The present invention is directed to aircraft docking systems and more particularly to safety enhancements for aircraft docking systems for automatic checking of the apron for obstacles before and during docking and for detection of fog and snowfall in front of the docking system. The present invention is further directed to methods implemented on such systems.
DESCRIPTION OF RELATED ART
In recent years, there has been a significantly increased number of passenger, cargo and other aircraft traffic, including takeoffs, landings and other aircraft ground traffic. Also, there has been a marked increase in the number of ground support vehicles which are required to offload cargo and to provide catering services and ongoing maintenance and support of all aircraft. With that substantial increase in ground traffic has come a need for greater control and safety in the docking and identification of aircraft on an airfield.
To that end, U.S. Pat. No. 6,023,665, issued Feb. 8, 2000, to the same inventor named in the present application and hereby incorporated by reference into the present disclosure, teaches a system for detecting, identifying and docking aircraft using laser pulses to obtain a profile of an object in the distance. The system initially scans the area in front of the gate until it locates and identifies an object. Once the object is identified as an airplane, the system tracks the airplane. By using the information from the profile, the system can in real time display the type of airplane, the distance from the stopping point and the lateral position of the airplane. The modes of operation of the system include a capture mode, in which an object is detected and determined to be an aircraft, and a tracking mode, in which the type of aircraft is verified and the motion of the aircraft toward the gate is monitored.
Referring to
FIG. 1A
, the docking guidance system of the above-referenced patent, generally designated
10
, provides for the computerized location of an object, verification of the identity of the object and tracking of the object, the object preferably being an aircraft. In operation, once the control tower
14
lands an aircraft
12
, it informs the system that the aircraft is approaching a gate
16
and the type of aircraft (i.e., 747, L-1011, etc.) expected. The system
10
then scans the area
19
in front of the gate
16
until it locates an object that it identifies as an airplane
12
. The system
10
then compares the measured profile of the aircraft
12
with a reference profile for the expected type of aircraft and evaluates other geometric criteria characteristic of the expected aircraft type. If the located aircraft, at a minimum specified distance (e.g., 12 m) before the stop position, does not match the expected profile and the other criteria, the system informs or signals the tower
14
, displays a stop sign and shuts down.
If the object is the expected aircraft
12
, the system
10
tracks it into the gate
16
by displaying in real time to the pilot the distance remaining to the proper stopping point and the lateral position of the plane
12
. The lateral position of the plane
12
is provided on a display
18
allowing the pilot to correct the position of the plane to approach the gate
16
from the correct angle. Once the airplane
12
is at its stopping point, that fact is shown on the display
18
and the pilot stops the plane.
Referring to
FIG. 1B
, the system
10
includes a Laser Range Finder (LRF)
20
, two mirrors
21
,
22
, a display unit
18
, two step motors
24
,
25
, and a microprocessor
26
. Suitable LRF products are sold by Laser Atlanta Corporation and are capable of emitting laser pulses, receiving the reflections of those pulses reflected off of distant objects and computing the distance to those objects.
The system
10
is arranged such that there is a connection
28
between the serial port of the LRF
20
and the microprocessor
26
. Through that connection, the LRF
20
sends measurement data approximately every {fraction (1/400)}th of a second to the microprocessor
26
. The hardware components generally designated
23
of the system
20
are controlled by the programmed microprocessor
26
. In addition, the microprocessor
26
feeds data to the display
18
. As the interface to the pilot, the display unit
18
is placed above the gate
16
to show the pilot how far the plane is from its stopping point
29
, the type of aircraft
30
the system believes is approaching and the lateral location of the plane. Using that display, the pilot can adjust the approach of the plane
12
to the gate
16
to ensure the plane is on the correct angle to reach the gate. If the display
18
shows the wrong aircraft type
30
, the pilot can abort the approach before any damage is done. That double check ensures the safety of the passengers, plane and airport facilities because if the system tries to dock a larger 747 at a gate where a 737 is expected, it likely will cause extensive damage.
In addition to the display
18
, the microprocessor
26
processes the data from the LRF
20
and controls the direction of the laser
20
through its connection
32
to the step motors
24
,
25
. The step motors
24
,
25
are connected to the mirrors
21
,
22
and move them in response to instructions from the microprocessor
26
. Thus, by controlling the step motors
24
,
25
, the microprocessor
26
can change the angle of the mirrors
21
,
22
and aim the laser pulses from the LRF
20
.
The mirrors
21
,
22
aim the laser by reflecting the laser pulses outward over the tarmac of the airport. In the preferred embodiment, the LRF
20
does not move. The scanning by the laser is done with mirrors. One mirror
22
controls the horizontal angle of the laser, while the other mirror
21
controls the vertical angle. By activating the step motors
24
,
25
, the microprocessor
26
controls the angle of the mirrors and thus the direction of the laser pulse.
The system
10
controls the horizontal mirror
22
to achieve a continuous horizontal scanning within a ±10 degree angle in approximately 0.1 degree angular steps which are equivalent to 16 microsteps per step with the Escap EDM-453 step motor. One angular step is taken for each reply from the reading unit, i.e., approximately every 2.5 ms. The vertical mirror
21
can be controlled to achieve a vertical scan between +20 and −30 degrees in approximately 0.1 degree angular steps with one step every 2.5 ms. The vertical mirror is used to scan vertically when the nose height is being determined and when the aircraft
12
is being identified. During the tracking mode, the vertical mirror
21
is continuously adjusted to keep the horizontal scan tracking the nose tip of the aircraft.
While the system disclosed in the above-cited patent detects the airplane, that system does not detect ground support vehicles or other objects in the apron of the docking area. Because of the pilot's limited field of view, the aircraft may collide with such ground support vehicles or other objects. Also, the system may give erroneous warnings in fog or snow, particularly the former.
Fog is most often seen between 10-25 m by the system. As that distance is closer, or in the area of, the stop position, the system will generate a gate blocked or ID-fail condition if the capture procedure triggers on the fog. The capture procedure needs a method to recognize that the object captured is most likely fog and is no obstruction to the docking procedure once the aircraft appears.
Log files taken during foggy conditions show that fog is reported like a solid object in front of the system. A sweep into fog often reports close to 100% echoes, and the echoes vary in distance only with a few decimeters of each other. Snowfall is most often more spread out, giving 60-80% echoes with a spread of 5-10 m. Thus, snow is generally easier to detect, i.e., discriminate from a solid object, than fog is.
FIGS. 2A and 2B
show sample images of fog, while
FIGS. 2C and 2D
show sample images of
Blank Rome LLP
Nguyen Tai T.
Safegate International AB
Wu Daniel J.
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