Image analysis – Applications
Reexamination Certificate
1998-11-10
2001-11-27
Mancuso, Joseph (Department: 2621)
Image analysis
Applications
C701S300000
Reexamination Certificate
active
06324295
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to systems for the in-flight refuelling of aircraft.
2. Discussion of Background
In-flight refuelling consists in transferring fuel from a tanker aircraft to a receiver aircraft using a hose which passes through what is commonly known as a boom and a telescopic line extending from this boom. The boom is fixed to the lower rear part of the fuselage of the tanker aircraft by a semi-rigid connection which allows it a certain freedom of movement. The boom and line assembly floats up under the empennage of the tanker aircraft by virtue of ailerons equipped with control surface which allow it to be steered. The total length of the boom and deployed line assembly may be as much as 15 or 20 meters. The receiver aircraft has a receptacle intended to receive the end of the line during refuelling. This receptacle is equipped with locking means for holding the line in place in relation to a pipe which allows the file from the tanker aircraft to be taken into a tank of the receiver aircraft.
The pilot of the receiver aircraft needs to bring his airplane up under the empennage of the tanker aircraft near to the line that extends behind the tanker aircraft, and keep his speed strictly identical to that of the tanker aircraft until the end of the refuelling operation.
The pilot of the receiver aircraft needs to bring his aeroplane up under the empennage of the tanker aircraft near to the line that extends behind the latter, and keep his speed strictly identical to that of the tanker aircraft until the end of the refuelling operation.
There are two ways of connecting the tanks of the tanker aircraft and of the receiver aircraft.
In the first case, the receiver aircraft is equipped with an in-flight refuelling line which extends in the field of view of the pilot, and the hose from the fuel tank of the tanker aircraft extends beyond the boom and the line in the form of a “basket” intended to receive the line of the receiver aircraft. It is therefore the pilot of the receiver aircraft who has to steer his airplane in such a way as to lock his line in the bottom of the basket.
In the second case, to which the present invention is more specifically related, the receiver aircraft is equipped only with a refuelling receptacle, and it is the end of the line from the tanker aircraft which is docked in the receptacle to allow fuel to be transferred. The line is guided by an operator placed in the rear of the tanker aircraft. This operator looks out through a window and performs the operations of coupling the two aircraft so that fuel can be transferred. To do this, the operator has control levers which operate servomotors that steer the boom so that the rear end of the boom/line assembly can be brought up close to the receptacle placed on the receiver aircraft. The position of this receptacle is identified by a painted mark on the aircraft skin. When the line is in the desired position, facing the receptacle, the operator initiates an additional deployment of the end of the telescopic line, and this engages and locks the line in the receptacle. Fuel transfer can then take place. Guiding the line towards the receptacle of the receiver aircraft is a tricky operation because of the relative movements of the two aircraft and of the boom, and because the control surfaces are extremely sensitive at the normal working altitudes and speeds. The operator has to operate the boom controls very gradually, and the time needed to make the connection between the line and the receptacle may be great (i.e., as much as a few minutes), especially if the surrounding air is turbulent.
SUMMARY OF THE INVENTION
For various reasons, it may be desirable for the operations to be performed without using an operator placed in the rear of the tanker aircraft.
An object of the present invention is therefore to design a system which allows the coupling operations to be performed without an operator placed in the rear of the tanker aircraft.
Another object of the present invention is to reduce the time needed to couple the line and the receptacle and thus, increase the refuelling rotation.
One idea might be to use two video cameras placed one on each side of the aircraft. These cameras, which would observe the refuelling scene from two different angles, would allow the objects in the scene to be reconstructed in three dimensions. From this, the coordinates of the receptacle and of the end of the line could be deduced in a three-dimensional (3D) reference frame.
However, although this solution is envisageable for robotic applications in an industrial environment, it becomes extremely complicated to employ on an in-flight refuelling aircraft with the operating constraints involved, and this makes its performance uncertain.
One of the difficulties is that of locking on to and tracking two objects of the image which move independently causing these objects to be obscured. Another difficulty arises from the use of variable focal length cameras. This type of equipment is needed in order to be able to guarantee that both objects will be present in the images simultaneously, even taking account of any possible turbulence, and so as to allow a good level of accuracy in extracting their co-ordinates in three dimensions, particularly in the final phase of guiding the line onto the receptacle.
The use of two variable focal length cameras intended to perform a three-dimensional reconstruction is extremely complicated because it entails instantaneous and precise knowledge of the focal lengths, and requires the optical axes of the two cameras to be automatically controlled as a function of their focal length; this then entails them being installed on platforms which, given the ambient environment and the temperatures imposed by the high altitude (of the order of −55° C.), is not simple.
The present invention aims to provide a solution which is simpler to implement than this two-camera solution.
According to the present invention, a coupling system has been proposed, particularly for in-flight refuelling, using means for automatically guiding the end of a line towards a coupling receptacle with a view to coupling the line and this receptacle, the line being deployable from one end of an orientable boom, the coupling system including:
a camera borne by the end of the boom and providing an image in the form of an electronic signal;
shape-recognition means coupled to the camera for recognizing, in the image provided by the camera, characteristic elements associated with the receptacle;
position-calculation means for determining, by calculation in the image provided by the camera, the difference between the position of the characteristic elements of the image at a given instant and a reference position originating from an image, stored in memory, of the line and of the receptacle when they are coupled;
means for deducing from the actual size of the receptacle, from the size and from the position of its projection in the image, the depth-wise distance between the end of the line and the receptacle; and
means for controlling the orientation of the boom and deploying the line on the basis of the differences thus measured, so that the line is brought closer to the receptacle by iteration until these differences have been canceled.
Thus, the idea proposed by the present invention is to place one camera on the boom, towards its rear end, and therefore close enough to the receptacle that is to be observed, to use the image produced to perform shape recognition and take distance measurements in the plane of the image, and to add to this the prior knowledge of the theoretical configuration of characteristic elements of the receptacle (or of an associated painted mark) in order to evaluate the distance between the line and the receptacle along the depth axis.
The guidance principle will then be to minimize these distances by iteration, that is to say, to use automatic speed control to gather onto a reference image.
Although it would be natural to use cameras which are as dis
Horaud Patrice
Valery Philippe
Wassner Hubert
Mancuso Joseph
Oblon & Spivak, McClelland, Maier & Neustadt P.C.
Sextant Avionique
Tabatabai Abolfazl
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