Data processing: vehicles – navigation – and relative location – Vehicle control – guidance – operation – or indication
Reexamination Certificate
2002-06-20
2003-07-01
Black, Thomas G. (Department: 3661)
Data processing: vehicles, navigation, and relative location
Vehicle control, guidance, operation, or indication
C701S003000, C701S008000, C701S121000, C701S301000, C340S961000, C342S029000, C342S455000
Reexamination Certificate
active
06587757
ABSTRACT:
The present invention relates to the guidance of an aircraft so as to allow it, once inserted into the traffic of an air corridor, to retain a minimum distance of separation with the aircraft preceding it so as to prevent any risk of collision.
The problem of insertion into the traffic of an air corridor, know as “follow traffic”, arose right from the beginnings of aviation, in respect of access to runways and has long been solved solely by the technique of fly by sight which consists, in respect of the pilot of an aircraft, in carrying out visual surveillance of his vicinity in order to tag the other aircraft flying nearby and especially any aircraft which may be preceding him on the same trajectory, and to act on his throttle sticks so as to preserve an apparent distance relative to this aircraft which is sufficient to avoid any risk of collision. This technique, still widely carried out, in the context of highly regulated procedures, is safe only in the event of good visibility and light traffic. Should the air traffic be somewhat heavy such as over Europe or the North American continent, the technique of fly by sight is used alongside the routing of the aircraft from the ground, by air controllers who assign positions and speeds to the various aircraft allowing them to insert themselves into the traffic of an air corridor while complying with the minimum separation distances between aircraft eliminating the risks of collision. However, even strengthened by traffic regulation by an air control authority, the safety of the fly by sight technique depends on the visibility conditions so that, in order to maintain one and the same safety level, the poorer the visibility conditions, the larger must be the minimum spacing between aircraft.
Navigation and radiocommunication equipment having progressed in terms of reliability and accuracy, it is envisaged that the extent of the domain of action of air controllers be limited to zones of heavy traffic with prescribed air corridors and that, outside of these zones, that is to say in the higher space, aircraft be granted mastery of their navigation so as to ensure better traffic flow. The downside of this autonomy of navigation in higher space is the need for the aircraft to ensure their anticollision safety by themselves. With this aim, and that of better safety, it is proposed to equip aircraft with a so-called “ADS-B” system, the initials standing for “Automatic Dependent Surveillance Broadcast”, via which an aircraft informs the various other aircraft flying nearby and the terrestrial air control stations within its range, of its position and its speed vector, either periodically or when interrogated.
An aircraft flying amid traffic consisting of other aircraft equipped with the ADS-B system is able to ascertain its situation relative to the various other aircraft and to forecast, in the short and medium term, the way in which this situation will alter and hence the collision risks incurred in the short and medium term, if no correction is made to the trajectories of the various relevant aircraft. Armed with this knowledge, it is capable of modifying its trajectory or of requesting another aircraft to modify its trajectory so as to eliminate risks of collision. Various methods directly usable by airborne navigation computers onboard aircraft have already been proposed for detecting the risks of collisions with other aircraft and for determining the course corrections allowing these risks to be eliminated at the cost of a minimum detour.
It is proposed here that the knowledge which an aircraft possesses, ever more often, of its position and its speed vector as well as of the positions and speed vectors of the various other aircraft flying nearby, by virtue of the ADS-B system and also by virtue of other systems such as airborne radars or means for communicating with ground tagging stations, be used to automate the maintaining of a longitudinal safety distance relative to another aircraft preceding it along its scheduled course. This additional aid afforded to the crew of the aircraft and to any air control authority involved is able to reduce the spacing between aircraft for one and the same safety level and hence to increase the traffic in an air corridor.
The subject of the invention is a process for guiding a so-called slave aircraft in the context of a convoy flight, behind another so-called master aircraft, on one and the same predetermined trajectory and with a preset minimum separation distance D
SEP
, consisting in giving the calculated air speed V
CAS,S
of the slave aircraft, that is to say calculated from measurements of temperature and static and dynamic pressures and known as “Calculated Air Speed”, an initial value V
CAS0,S,
in periodically deducing the distance separating the slave aircraft from the master aircraft from the geographical position of the slave aircraft and from that of the master aircraft at one and the same instant, and from the known shape of the trajectory followed by the master and slave aircraft, then in periodically correcting the calculated air speed V
CAS,S
of the slave aircraft by modifying it with a corrective term E derived from the discrepancy noted between the measured separation distance D and the preset minimum separation distance D
SEP
, this guidance process being defined by a recurrence relation of the form:
&AutoRightMatch;
{
V
CAS
,
S
(
t
0
)
=
V
CAS0
,
S
(
t
0
)
V
CAS
,
S
(
t
0
+
kΔ
t
)
=
V
CAS
,
S
(
t
0
+
(
k
-
1
)
Δt
)
+
E
(
(
D
SEP
-
D
M
)
,
(
t
0
+
(
k
-
1
)
Δ
t
)
)
&Dgr;t being the periodicity of the correction.
Advantageously, the initial value of the calculated air speed of the slave aircraft is taken equal to the calculated air speed scheduled during the preparation of the flight plan of the slave aircraft 2 at the place where it is situated at the moment of implementation of the guidance process, this calculated air speed resulting from the application of a 4D defining law, that is to say dependent on the four variables: altitude, time, latitude and longitude, this case being tailored to a situation where the aircraft is descending, for example, on the approach to a runway.
Advantageously, the initial value of the calculated air speed of the slave aircraft is taken equal to a calculated air speed and adopted in order to optimize consumption. This is applied to the case where the slave aircraft is cruising.
Advantageously, the initial value of the calculated air speed of the slave aircraft is taken equal to the calculated air speed of the master aircraft
1
at the moment at which it passed substantially the same point of the trajectory.
Advantageously, one is given a so-called effective margin of tolerance &Dgr;L
e
, as a percent, in the measured distance D
M
relative to the preset distance D
SEP
below which the corrective term E takes a zero value and above which the corrective term takes a non zero value.
Advantageously, a hysteresis phenomenon is introduced around the effective margin of tolerance &Dgr;L
e
, by giving the latter a reduced value upon each detection of its overshoot, doing so as long as the overshoot lasts.
Advantageously, in the case where there is a preset margin of tolerance &Dgr;L
c
, an effective tolerance margin &Dgr;L
e
which is stricter than the preset tolerance margin &Dgr;L
c
is adopted by applying a positive safety coefficient k′ of less than 1 to the preset tolerance margin &Dgr;L
c
, for example 0.8 so that the preset tolerance margin &Dgr;L
c
is never reached:
&Dgr;L
e
=k′&Dgr;L
c
with 0<k′≦1
Advantageously, in the case where the effective tolerance margin &Dgr;L
e
is deduced from a preset tolerance margin &Dgr;L
c
by applying a safety coefficient k′, a hysteresis phenomenon is introduced around the effective tolerance margin &Dgr;L
e
by giving the latter, when it has just been overshot, a reduced value deduced from the preset tolerance margin &Dgr;L
c
by applying a positive hysteresis coefficient k″
Black Thomas G.
Mancho Ronnie
Thales
LandOfFree
Method for guiding an aircraft during a convoy flight does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Method for guiding an aircraft during a convoy flight, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method for guiding an aircraft during a convoy flight will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3004226