U.S. patent number 8,560,148 [Application Number 13/292,685] was granted by the patent office on 2013-10-15 for method and apparatus for air traffic trajectory synchronization.
This patent grant is currently assigned to Lockheed Martin Corporation. The grantee listed for this patent is Joel Klooster, Sergio Torres. Invention is credited to Joel Klooster, Sergio Torres.
United States Patent |
8,560,148 |
Torres , et al. |
October 15, 2013 |
Method and apparatus for air traffic trajectory synchronization
Abstract
According to aspects of the embodiments, there is provided an
apparatus and method to synchronize the distinct trajectories
predicted by a flight management system and air navigation service
provider. A comparison model is generated that indicates
differences between an aircraft trajectory and a ground trajectory.
The aircraft trajectory is updated to reflect identified
discrepancies and restriction violations between the trajectories.
Upon successful completion of the first designated change, a
notification manager is used to issue a notification of the
designated change to the flight plan trajectory. A modified ground
trajectory is produced that incorporates the designated change to
the flight plan trajectory. The comparison is repeated until the
discrepancies of the trajectories are operationally
insignificant.
Inventors: |
Torres; Sergio (Bethesda,
MD), Klooster; Joel (Grand Rapids, MI) |
Applicant: |
Name |
City |
State |
Country |
Type |
Torres; Sergio
Klooster; Joel |
Bethesda
Grand Rapids |
MD
MI |
US
US |
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|
Assignee: |
Lockheed Martin Corporation
(Bethesda, MD)
|
Family
ID: |
46020397 |
Appl.
No.: |
13/292,685 |
Filed: |
November 9, 2011 |
Prior Publication Data
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Document
Identifier |
Publication Date |
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US 20120116614 A1 |
May 10, 2012 |
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Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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61411628 |
Nov 9, 2010 |
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Current U.S.
Class: |
701/3 |
Current CPC
Class: |
G08G
5/0039 (20130101); G08G 5/0013 (20130101); G08G
5/0082 (20130101) |
Current International
Class: |
G01C
23/00 (20060101); G06F 17/00 (20060101); G06F
7/00 (20060101); G05D 3/00 (20060101); G05D
1/00 (20060101) |
Field of
Search: |
;701/3 |
References Cited
[Referenced By]
U.S. Patent Documents
Other References
Klooster, J. et al; "Trajectory synchronization and negotiation in
Trajectory Based Operations"; Digital Avionics Systems Conference
(DASC), 2010 IEEE/AIAA 29th (Utah); Oct. 3-7, 2010, pp.
1.A.3-1-1.A.3-11. cited by applicant .
Nilim, Arnab et al. "Trajectory-based Air Traffic Management
(TB-ATM) under Weather Uncertainty." Proc of 4th USAEurope Air
Traffic Management Research Development Seminar (2001) : 11 pages.
Print. cited by applicant.
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Primary Examiner: Cheung; Mary
Assistant Examiner: Brushaber; Frederick
Attorney, Agent or Firm: Prass, Jr.; Ronald E. Prass LLP
Parent Case Text
CROSS-REFERENCES TO RELATED APPLICATIONS
This application claims priority to U.S. Provisional Application
No. 61/411,628, entitled "METHOD AND APPARATUS FOR AIR TRAFFIC
TRAJECTORY SYNCHRONIZATION," filed Nov. 9, 2010, by Sergio TORRES
et al, the entire disclosure of which is incorporated herein by
reference in its entirety.
This application is related to the following co-pending
applications, which is hereby incorporated by reference in its
entirety: "METHOD AND APPARATUS FOR DYNAMIC AIR TRAFFIC TRAJECTORY
SYNCHRONIZATION", U.S. Provisional Application No. 61/542,071,
filed on 30 Sep. 2011, by David S. CHAN et al.
Claims
What is claimed is:
1. A method for trajectory synchronization comprising: receiving,
with a processor, an aircraft trajectory for an aircraft in flight
from a first system; receiving, with the processor, a separate
ground trajectory for the aircraft in flight from a second system,
the separate ground trajectory comprising a series of points
associated with various flight points or trajectory change points
for; the aircraft in flight; comparing, with the processor, the
received aircraft trajectory and the received separate ground
trajectory to detect discrepancies arising along a proposed route
of flight for the aircraft in flight; verifying, with the
processor, that the proposed route of flight for the aircraft in
fight complies with at least one aircraft restriction; and sending
a message to the first system with instruction for correcting at
least one of detected discrepancies and verified restriction
violations arising from the comparing and the verifying
constituting a synchronizing of the aircraft trajectory and the
separate ground trajectory as a synchronized trajectory for the
aircraft inflight.
2. The method of claim 1, further comprising: receiving from the
first system a four-dimensional trajectory comprising correction of
the detected discrepancies and verified restriction violations.
3. The method of claim 2, further comprising: receiving an updated
separate ground trajectory from the second system after processing
of the four-dimensional trajectory from the first system and
generating a new synchronized trajectory for the aircraft in flight
using trajectory change point attributes including one or more of
Longitude, Altitude, Speed and Time obtained from the
four-dimensional trajectory built in the first system.
4. The method in accordance to claim 3, the method further
comprising: reconforming the updated separate ground trajectory
when the aircraft receives a departure message or when at least one
of the first system and the second system receives a sector
crossing message.
5. The method of claim 4, further comprising: monitoring and
updating the updated separate ground trajectory and the aircraft
trajectory based on information pertaining to at least one of
ground changes and changes in environmental conditions.
6. The method of claim 5, wherein the comparing the aircraft
trajectory and the separate ground trajectory to detect
discrepancies is based on detecting discrepancies in latitude and
longitude information.
7. The method of claim 6, wherein the comparing is achieved with a
cusp-to-cusp differencing algorithm.
8. The method of claim 7, wherein the at least one aircraft
restriction is one of an altitude restriction and a speed
restriction.
9. A system for synchronizing distinct trajectories in airspace,
comprising: a computer executing an interface to receive an
aircraft trajectory for an aircraft in flight from a first system
and a separate ground trajectory for the aircraft in flight from a
second system , the separate ground trajectory comprising a series
of points associated with various flight points or trajectory
change points for the aircraft in flight; and a processor and a
memory coupled to the processor, the memory having stored program
instructions executable by the processor to: compare the received
aircraft trajectory and the received separate ground trajectory to
detect discrepancies arising along a proposed route of flight for
the aircraft in flight; verify that the proposed route of flight
for the aircraft in flight complies with at least one aircraft
restriction; and execute a notification manager to send a message
to the first system with instruction for correcting at least one of
detected discrepancies and verified restriction violations arising
from the comparing and the verifying constituting a synchronizing
of the aircraft trajectory and the separate ground trajectory as a
synchronized trajectory for the aircraft inflight.
10. The system of claim 9, the interface further receiving from the
first system a four-dimensional trajectory comprising correction of
the detected discrepancies and verified restriction violations.
11. The system of claim 10, the interface further receiving an
updated separate ground trajectory from the second system after
processing of the four-dimensional trajectory from the first system
and generating a new synchronized trajectory for the aircraft in
flight using trajectory change point attributes including one or
more of Latitude, Longitude, Altitude, Speed and Time obtained from
the four-dimensional trajectory built in the first system.
12. The system of claim 11, the processor further performing:
reconforming of the updated separate ground trajectory when the
aircraft receives a departure message or when the aircraft receives
a flight information sector crossing message.
13. The system of claim 12, the processor further performing:
monitoring and updating of the updated separate ground trajectory
and the aircraft trajectory based on information pertaining to at
least one of ground changes and changes in environmental
conditions.
14. The system of claim 13, wherein the comparing the aircraft
trajectory and the separate ground trajectory to detect
discrepancies is based on detecting discrepancies in latitude and
longitude information.
15. The system of claim 14, wherein the comparing is achieved with
a cusp-to-cusp differencing algorithm.
16. The system of claim 15, wherein the at least one aircraft
restriction is one of an altitude restriction and a speed
restriction.
17. The system of claim 16, wherein the first system and the second
system are separate one of a flight management system, an
air-traffic control system, and an air traffic management
system.
18. A non-transitory computer-readable medium having instructions
that, when executed by a processor, cause the processor to perform
a method for trajectory synchronization from a plurality of
systems, the method comprising: receiving an aircraft trajectory
for an aircraft in flight from a first system; receiving a separate
ground trajectory for the aircraft in flight from a second system,
the separate ground trajectory comprising a series of points
associated with various flight points or trajectory change points
for the aircraft in flight; comparing the received aircraft
trajectory and the received separate ground trajectory to verify at
least one route agreement for the aircraft in flight as a
synchronized trajectory; verifying from the received aircraft
trajectory and the received separate ground trajectory that a
proposed route of flight complies with at least one aircraft
restriction; and sending a message to at least one of the plurality
of systems with instruction for correcting at least one of detected
discrepancies and verified restriction violations arising from the
verifying and the comparing of the received aircraft trajectory and
the received separate ground trajectory.
19. The non-transitory computer-readable medium of claim 18,
wherein the comparing is achieved with a cusp-to-cusp differencing
algorithm.
20. The non-transitory computer-readable medium of claim 19, the
method further comprising causing the computer to receive from one
of the plurality of systems a four-dimensional trajectory
comprising correction of the detected discrepancies and the
verified restriction violations.
21. The non-transitory computer-readable medium of claim 20,
wherein the comparing the aircraft trajectory and the separate
ground trajectory to detect discrepancies is based on detecting
discrepancies in latitude and longitude information.
22. The non-transitory computer-readable medium of claim 21,
wherein the at least one aircraft restriction is one of an altitude
restriction and a speed restriction.
23. The non-transitory computer-readable medium of claim 22, the
method further comprising monitoring and updating the separate
ground trajectory and the aircraft trajectory based on information
pertaining to at least one of ground changes and changes in
environmental conditions.
Description
BACKGROUND
1. Field of the Disclosed Embodiments
The disclosure relates to air traffic trajectory synchronization,
in particular to the synchronizing of distinct trajectories
predicted by a plurality of systems.
2. Introduction
In trajectory based operations (TBO), air-ground and ground-ground
interoperability and trajectory synchronization among the various
systems is required since each of these systems rely on an accurate
prediction of the flight path in four dimensions (4D trajectory or
4DT). Without proper synchronization, the Air Traffic Control (ATC)
and Air Traffic Management (ATM) of the airspace is forced to add
significant uncertainty into its prediction of the aircraft
trajectory, thus decreasing the potential capacity of the available
airspace and the efficiency of operations. The uncertainty that
results from air-ground and ground-ground trajectory discrepancies
also leads to non-optimal tactical intervention. The goal of
air-ground (or ground-ground) trajectory synchronization is to
produce trajectories in disparate systems whose discrepancies are
operationally insignificant, increasing the likelihood of flying
the planned conflict-free and business-preferred trajectories. In
addition, if conditions change in the ground requiring alternative
trajectories (i.e., projecting for conflict resolution or schedule
management, for instance), then the ATC/ATM systems have to be able
to independently build new trajectories that are compatible with
user preferences and with the requirements of the Flight Management
System (FMS) on board the aircraft.
In the field of flight management systems (FMSs), the technical
problem to be solved is related to the use by the ground of
predictions calculated by the FMS along the flight plan (location,
altitude, speed, fuel, time of passage, for each point on the
flight plan). In recent studies, it emerged that a significant
improvement in capacity and safety for future ATM systems lay on
the one hand in the collaboration between the Air Navigation
Service Provider (ANSP) and onboard (aircraft) operators, in
particular the synchronization of route and flight data, and on the
other hand in the accuracy of the predicted trajectories.
The ground-based operators and supporting automation tools can use
the predictions issued by aircraft to organize the traffic, balance
the traffic load among each control sector, anticipate the dynamic
control sector segmentations and groupings, sequence the aircraft
more effectively in the terminal procedures, and lastly be able to
deploy an end-to-end ATM system ("4D" and "Gate to Gate"
concepts).
All these operations require both regular synchronization and
precision in trajectory forecasts carried out on the ground and on
board. One of the main challenges to Trajectory Based Operations
(TBO) is interoperability and coordination among systems
(air-ground and ground-ground). It is foreseen that a primary means
to respond to this
Challenge is to provide a common view of operations as provided by
synchronized trajectories. 4DTs provide the basis for both
strategic planning and tactical operations, and as such they are
key enablers of TBO. On board the aircraft, the FMS uses a
trajectory for closed-loop guidance by way of the automatic flight
control system (AFCS). In ground systems, the trajectory provides
the information that is required for planning and for performing
critical air traffic control and traffic flow management functions,
such as: scheduling, conflict prediction, intra-sector hand off,
separation management and conformance monitoring. With such a vast
range of uses, the unique set of trajectory requirements (which at
times may be contradictory) applicable to each function cannot be
met in an efficient manner by simply sharing a common trajectory. A
trajectory used to guide the aircraft requires a different level of
fidelity than a trajectory used to estimate sector load in the
ground a few hours into the future.
Previous studies identified various Trajectory Synchronization
approaches, including: Flight Intent synchronization, Aircraft
Intent (AI) synchronization, Behavior Model synchronization,
Predicted Trajectory synchronization. Flight intent is primarily
the information carried by the flight plan but it is insufficient
for accurate synchronization because it does not contain enough
information to build from it an unambiguous rendition of the flight
path in 4D (i.e. multiple dissimilar trajectories can be generated
from the same flight plan). Aircraft intent-based trajectory
synchronization relies on using the FMS provided AI so it lacks all
of the knowledge available by the ground system. Behavior Model
data consists of a list of the maneuvers that the aircraft needs to
execute in order to follow the flight plan, thus it is similar to
aircraft intent data except that the information is expressed more
abstractly. Synchronization using aircraft intent or behavior model
data does not account for differences in weather forecast models
and aircraft performance models, therefore could result in
significantly different 4D predictions. The last approach,
Predicted Trajectory synchronization consists of down-linking the
FMS predicted 4D trajectory (for example via Automatic Dependent
Surveillance-Contract (ADS-C) Extended Projected Profile (EPP)
reports) and using it "as is" by the ground systems. This approach
is limited by the fact that the FMS 4D trajectory is a prediction
for current conditions and constraints only, and if conditions
change in the ground that require building alternative trajectories
the FMS 4D-trajectory has to be discarded and a completely new
trajectory has to be built on the ground system, opening the
possibility for breaking synchronization.
For the reasons stated above, and for other reasons stated below
which will become apparent to those skilled in the art upon reading
and understanding the present specification there is need in the
art for a system and method that synchronizes trajectories from
disparate systems.
SUMMARY
According to aspects of the embodiments, there is provided an
apparatus and method to synchronize the distinct trajectories
predicted by a flight management system and air navigation service
provider. A comparison model is generated that indicates
differences between a Flight Management System (FMS) trajectory and
a ground trajectory. A new synchronized trajectory is generated
that resolves identified discrepancies and restriction violations
between the trajectories. The synchronized trajectory is built
first by resolving discrepancies in the converted route of flight
(the 2D path along the Latitude and Longitude dimensions) and then,
once 2D differences have been resolved, altitude and speed
restriction compliances is verified. Upon successful resolution of
2D path discrepancies and restriction compliance violations, the
synchronized trajectory is build by using the FMS trajectory as the
basis.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 illustrates a practical application in accordance to an
embodiment;
FIG. 2 is a block diagram of a hardware and operating environment
in which different embodiments can be practiced;
FIG. 3 transaction flow diagram illustrating the manner in which
the flight management system (FMS) and ATC computer of FIG. 1
cooperate to perform trajectory synchronization and exchange of
data relating to a flight plan trajectory in accordance to an
embodiment;
FIG. 4 is a block diagram of a pre-departure trajectory
synchronization in accordance to an embodiment;
FIG. 5 is a block diagram of a in-flight trajectory synchronization
in accordance to an embodiment; and
FIG. 6 is a flowchart of a method for trajectory synchronization in
accordance to an embodiment.
DETAILED DESCRIPTION OF THE DISCLOSED EMBODIMENTS
Additional features and advantages of the disclosure will be set
forth in the description which follows, and in part will be obvious
from the description, or may be learned by practice of the
disclosure. The features and advantages of the disclosure may be
realized and obtained by means of the instruments and combinations
particularly pointed out in the appended claims. These and other
features of the present disclosure will become more fully apparent
from the following description and appended claims, or may be
learned by the practice of the disclosure as set forth herein.
Various embodiments of the disclosure are discussed in detail
below. While specific implementations are discussed, it should be
understood that this is done for illustration purposes only. A
person skilled in the relevant art will recognize that other
components and configurations may be used without parting from the
spirit and scope of the disclosure.
Aspects of the disclosed embodiments relate to a method for
trajectory synchronization comprising receiving a first trajectory
from any system (but to facilitate the discussion it will be
referred to as the aircraft trajectory, and could be for instance
the 4D trajectory generated by the FMS on board the aircraft) and a
ground trajectory from a second system comprising a series of
points associated with various flight constraints for an aircraft;
comparing the aircraft trajectory and the ground trajectory to
detect discrepancies; verifying from the aircraft trajectory that a
proposed flight plan complies with at least one aircraft
restriction; and sending a message to the first system with
instruction for correcting identified discrepancies and restriction
violations from the comparing and the verifying of the aircraft
trajectory and the ground trajectory.
In yet another aspect the disclosed embodiments the method further
comprises receiving from the first system a four-dimensional
trajectory comprising correction of the identified discrepancies
and restriction violations.
In yet another aspect the disclosed embodiments the method further
comprises receiving an updated ground trajectory after processing
of the four-dimensional trajectory from the first system by the
second system.
In yet another aspect the disclosed embodiments the method further
comprises reconforming the updated ground trajectory if the
aircraft has received a departure message or if the aircraft has
received a sector crossing message (such as entry into the
controlled airspace).
In yet another aspect the disclosed embodiments the method further
comprises monitoring and updating the updated ground trajectory and
the aircraft trajectory based on information pertaining to at least
one of ground changes, change in environmental conditions.
In yet another aspect the disclosed embodiments wherein comparing
the aircraft trajectory and the ground trajectory to detect
discrepancies is based on detecting discrepancies in latitude and
longitude information.
In yet another aspect the disclosed embodiments the method further
comprises wherein comparing is achieved with a cusp-to-cusp
differencing algorithm (where a trajectory cusp or trajectory
change point is any of the points defining the trajectory data
structure).
In yet another aspect the disclosed embodiments wherein the at
least one aircraft restriction is selected from the group
consisting of altitude restriction and speed restriction.
Still another aspects of the disclosed embodiments relate to a
system for synchronizing distinct trajectories in airspace, the
system comprising: a computer executing an interface to receiving
an aircraft trajectory from a first system and a ground trajectory
from a second system comprising a series of points associated with
various flight constraints for an aircraft; and a processor and a
memory coupled to the processor, wherein the memory comprises
program instructions executable by the processor to: comparing the
aircraft trajectory and the ground trajectory to detect
discrepancies; verifying from the aircraft trajectory that a
proposed flight plan complies with at least one aircraft
restriction; wherein the computer executes a notification manager
to send a message to the first system with instruction for
correcting identified discrepancies restriction violations from the
verifying and the comparing of the aircraft trajectory and the
ground trajectory.
In still yet another aspect of the disclosed embodiments relate to
a non-transitory computer-readable medium having instructions that
when compiled by a processor perform trajectory synchronization
from a plurality of systems comprising: a computer-usable data
carrier storing instructions, the instructions when executed by a
computer causing the computer to perform trajectory synchronization
by: comparing the trajectories to verify at least one route
agreement for an aircraft; verifying from the trajectories that a
proposed flight plan complies with at least one aircraft
restriction; and
Sending a message to at least one of the plurality of systems with
instruction for correcting identified discrepancies and restriction
violations from the verifying and the comparing of the
trajectories.
The term "operator" as used herein refers to an airline, a cargo
operator, a business jet operation, or the pilot in single pilot
operations.
The term "communication", or "message" as used herein refers
communications through Automatic Dependent Surveillance-Contract
("ADS-C"), Controller Pilot Data Link Communications ("CPDLC"),
ARINC devices, radio frequency devices, microwave devices, and/or
the like.
Provided below is an example of acronyms found in trajectory
synchronization: Air Traffic Management (ATM); Flight Management
System (FMS); Air Traffic Control (ATC); En Route Automation
Modernization (ERAM); Common Automated Radar Terminal System
(Common ARTS); Trajectory Based Operations (TBO); Air Navigation
Service Provider (ANSP); US Next Generation Air Transport System
(NextGen); Single European Sky ATM Research (SESAR); 4D Trajectory
for Data Link (4DTRAD); automatic flight control system (AFCS);
Flight Path Intent Service (FLIPINT); 4-Dimensional Trajectory
(4DT) in space (latitude, longitude, altitude) and time; message
(Msg); Special Activities Airspace (SAA); Traffic Flow Management
(TFM); Trajectory predictor (TP); Flight Information Region
(FIR).
FIG. 1 illustrates a practical application to synchronize distinct
trajectories in accordance to an embodiment. FIG. 1 diagrams the
data collection, up-link/down-link, and trajectory synchronization
of the invention. In a preferred embodiment, the invention
predominantly uses existing equipment. For example, an aircraft 50
creates an aircraft trajectory which is saved in a memory storage
location (not shown) in the aircraft or in an external location. A
flight plan is made up of interlinked check points (or flight
points). At each flight point, as far as the destination airport,
the flight management system provides predictions: time of passage,
speed, altitude, and fuel remaining on board. The aircraft
trajectory is down-linked via an antenna 162 to a ground station
such as ATC 30 and ATM 40 where the aircraft trajectory can be
synchronized or processed to be synchronized with other
trajectories as shown in FIG. 3. Communication with originating
aircraft 50, other aircrafts, and other ground facilities is
conducted via an up-link/down-link antenna 16. In an alternative
embodiment, any communicative device, such as for example any
electronic signal transmitting and receiving device, may be used
that enables ATC 30 system to function as described herein.
The ground stations ATC 30 and ATM 40 could also communicate using
a dedicated connection or through a network such as the interne.
Additionally, Flight Information Regions (FIR) and terminal region
data is provided by the ATC 30 and ATM 40, as part of the ATM data
family, for different positions of the aircraft 50 relative to the
airport 60. ATC 30 and ATM 40 comprise hardware and software that
are well-known in the art. Both ATC and ATM 40 includes a processor
that is communicatively coupled to graphical display interface and
is programmed to generate and relay trajectory predictions, flight
plans, ground traffic instructions to ground-based, taxiing
aircraft, and other communication well known to those in the art.
To enable processor to function as described herein, and in the
exemplary embodiment, information, such as aircraft specification
data and airport runway and/or taxiway maps, is provided to the
processor. Moreover, data is provided to processor from surface
ground radar systems, as well as data from aircraft-based Automatic
Dependent Surveillance-Broadcast (ADS-B) systems. Alternatively,
any applicable information, such as for example weather data from
Automated Weather Observing System (AWOS) equipped units, may be
provided to processor that may enable ATC system to function as
described herein.
FIG. 2 is a block diagram of hardware and operating environment in
which different embodiments can be practiced. An FMS computer 200,
in aircraft 50, conventionally comprises a central processing unit
202 which communicates with an input-output interface 215, a
program memory 206, a working memory 204, a data storage memory
206, and circuits 210 for transferring data between these various
elements. The input-output interface is linked to various devices
such as a user interface 219, a board display (BD) 217, sensors
221, and other items well known to those in the art. Programs
instructions executable by the processor 202, specific to the
aircraft are stored in the data memory 206. The program
instructions are transferred to the working memory so as to produce
an aircraft trajectory, to receive changes or messages with
instructions as to changes, or to update the aircraft trajectory.
The FMS computer 200 is linked to a ground/onboard communication
system 162 which is in turn linked to ATC 30 and ATM 40 via a
communication link such as a C/P-DLC digital link 225 or Automatic
Dependent Surveillance-Contract (ADS-C) link.
FIG. 3 transaction flow diagram illustrating the manner in which
the flight management system (FMS) 200 and ATC computer of FIG. 1
cooperate to perform trajectory synchronization and exchange of
data relating to a flight plan trajectory in accordance to an
embodiment. It should be noted that synchronizer 307 need not be
separate and distinct from both FMS 200 and ATC 30. It is expected
that synchronizer 307 would be in the same facility or it could be
distributed between ATC 30 and FMS 200. It is likewise possible
that synchronizer 307 is in a remote location and that data is
being exchange through a communication channel such as a satellite
network. The FMS 200 down-links to the synchronizer 307 an aircraft
trajectory 315; the ATC 30 down links a ground trajectory 320 to
the synchronizer 307; in step 325 verification of route agreement
is made by comparing the aircraft trajectory 315 with the ground
trajectory 320; in step 325 the synchronizer 307 does a
verification of restriction compliance in the aircraft trajectory
315; the synchronizer 307 sends the FMS 200 instructions 330 to
correct for discrepancies and violations detected in step 325; the
FMS 200 applies the changes identified and generates 335 a
four-dimensional trajectory (4DT) in space (latitude, longitude,
altitude) and time; the 4DT is down linked to the synchronizer 307;
The synchronizer in step 340 down links the 4DT to the ATC so as to
provide the information needed on the ground for reconstruction of
realistic alternative trajectories; in step 345, the ATC 30 builds
a trajectory using the 4DT cusps which is uploaded to the
synchronizer 307; a mechanism is maintained to continuously perform
updates 360 so as to perform initial longitudinal
(time)re-conformance, conformance monitoring, and wind
synchronization which tend to change at least aircraft
trajectory.
The trajectory comparison algorithm for step 325 should initially
identifies differences in the 2D path as follows:
TABLE-US-00001 Identifies discrepancies in the 2D path between two
trajectories T1: trajectory 1; T2: trajectory 2 (i) Perpendicularly
(or closest distance if perp. does not exist) project T1 cusps on
T2 segments; (ii) Perpendicularly (or closest distance if perp.
does not exist) project T2 cusps on T1 segments; (iii) Find
E.sup..perp. = the largest perpendicular separation distance
between T1- T2 (from previous steps); If E.sup..perp. <
.theta..sup..perp.: trajectories are synchronized in the horizontal
dimension (.theta..sup..perp. = threshold) Else, list of distances
di > .theta..sup..perp. are identified discrepancies
In step 345, the ATC 30 builds a trajectory using the 4DT cusps
using an algorithm to build the ground trajectory using FMS
trajectory change points (TCP):
TABLE-US-00002 1. Build a new trajectory appending segments
constructed from cusp location (Latitude, Longitude), altitude and
time equal to those copied from the FMS TCP 2. If the estimated
error in the initial ground speed of the segment is larger than a
threshold (determined based on error propagation) then set the
segment acceleration to zero and the speeds to their implied value.
.DELTA..times..times..DELTA..times..times..DELTA..times..times.
##EQU00001## where, V.sub.g = ground speed L = segment length
.DELTA.h = altitude change inside the segment .DELTA.T = segment
duration ROCD = rate of climb or descent 3. Else, compute segment
acceleration constrained to leave cusp times unchanged:
.times..times..DELTA..times..times..DELTA..times..times.
##EQU00002## where a = acceleration L = segment length (along route
distance) v0 = computed ground speed at the start of the segment
vTAS = FMS speed (Mach or CAS) that applies to the start of the
segment vw = component of wind velocity vector along the direction
of the segment .DELTA.T = segment duration
The Algorithm to build the ground trajectory using FMS trajectory
change points (TCP) Thresholds & Errors can be express as
follows:
TABLE-US-00003 1. In the zero acceleration assumption (constant
implied speed) case, there will be longitudinal errors that reach a
maximum near the segment mid point (by construction segment end
points are constrained by TCPs). The errors are present if the real
acceleration (a) in the segment is not null.* VTAS and ROCD changes
value during a constant Mach/CAS descent or climb segment By
construction, cross-track errors are not expected (except for minor
distortion due to WGS84 geodesics vs. spherical earth modeling or
differences in the details of how turns are represented in the two
systems) The maximum longitudinal error grows with segment duration
(.DELTA.T):
.times..DELTA..times..times..times..times..times..times..times..times..tim-
es. ##EQU00003##
.times..times..times..times..times..times..times..times..times..times..ti-
mes..times..times..times..times..times..times..times..times..times..times.-
.times..times..times..times. ##EQU00003.2## 2. Maximum longitudinal
errors in the second case (implied constant acceleration) due to
jerk (the error arises due to assuming constant acceleration when
in reality it is not):
.times..times..DELTA..times..times..times..times..times..times..times..tim-
es..times..times..times..times..times..times..times. ##EQU00004##
3. Longitudinal errors in the second case (implied constant
acceleration) due variance in v0:
.DELTA..times..times..times..sigma..times. ##EQU00005##
.sigma..times..times..times..times..times..times..times..times..times..ti-
mes..times..times..times..times..times..times..times..times..times..times.
##EQU00005.2##
The disclosed embodiments may concern synchronizing the distinct
trajectories predicted by the aircraft Flight Management System
(FMS), the ground Air-Traffic Control (ATC) system and other Air
Traffic Management (ATM) systems. Previous trajectory
synchronization approaches can be classified according to the type
of data that is exchanged such as (a) Flight Intent, (b) Aircraft
Intent (Al), (c) Behavior Model, or (d) Predicted Trajectory.
Flight intent may primarily be the information carried by the
flight plan (FP) but it is insufficient for accurate
synchronization because it does not contain enough information to
build from it an unambiguous rendition of the flight path in four
dimensions (4D) (i.e., multiple dissimilar trajectories can be
generated from the same flight plan). Some attempts have been made
to improve the near-range estimation capability of the ground-based
systems based solely on the flight intent and tracking information,
but more accurate levels of synchronization are achievable with
better air-ground information exchange.
Aircraft intent-based trajectory synchronization may rely on using
the FMS provided AI that specifies the guidance modes and control
instructions needed to build the 4D trajectory that executes the
flight plan. However, often times the ground system has more
information than the FMS (i.e. restrictions and background traffic)
and needs to work with a trajectory that reflects all of the
knowledge available by the ground system; secondly, even though two
trajectory predictors can start with the same AI inputs,
differences in weather forecast models and aircraft performance
models could result in significantly different 4D predictions.
The amount of AI data that must be exchanged to synchronize
trajectories may also be prohibitive using existing data links.
Similar drawbacks affect the recently proposed exchange of behavior
model (i.e. list of maneuvers required to execute the flight plan)
as a means for trajectory synchronization. The fourth
synchronization approach, consisting of downlinking the FMS
predicted 4D-trajectory and using it "as is" by the ground systems
has the advantage that it may encode user preferences. However,
this approach is limited by the fact that the FMS 4D-trajectory is
a prediction for current conditions and constraints (flight points
or trajectory change points) only, and if conditions change in the
ground that require building alternative trajectories the FMS
4D-trajectory has to be discarded and a completely new trajectory
has to be built in the ground, opening the possibility for breaking
synchronization.
The disclosed embodiments may provide a process for trajectory
synchronization based on sequential stages coordinated by the
ground service provider (for instance ATC or traffic flow
managers). The following stages may describe the process for
air-ground trajectory synchronization only (a similar process is
used for ground-ground trajectory synchronization):
In FIG. 4 and FIG. 5 the trajectory synchronization will be
described using method language which is customarily found with
reference to a flowchart that enables one skilled in the art to
develop such programs, firmware, or hardware, including such
instructions to carry out the methods on suitable computers,
executing the instructions from computer-readable media. Therefore,
although described in procedural terms, one of ordinary skill in
the art will appreciate that implementations can be made using
hardware components or any other design environment that provides
the required relationships.
FIG. 4 is a block diagram of a pre-departure trajectory
synchronization in accordance to an embodiment.
A. Pre-Departure/Pre-Flight Information Region (FIR) Crossing
Phase:
In step 410, an initial trajectory request: upon reception of the
flight plan (FP) by the ground system and having reached a time
which is a parameter number of minutes before the estimated
departure time (if the flight is internal to the facility or the
extended facility--i.e. the NAS--) or before the FIR crossing the
ground system issues a trajectory request (TR) to the air system;
the FMS trajectory may be down-linked to the ATC system. In step
420, ground TP builds 4DT from the FP. In step 430 the ANSP
establishes ADS-C contract from in order to automatically obtain
the 4DT objects created in the FMS. In step 440 the aircraft 50
builds a high fidelity trajectory from the FP and makes it
available via ADS-C downlink to the ground systems. In step 450,
the high fidelity trajectory of step 440 and the 4DT from the
ground TP are verified.
In step 450 verification of route agreement is made by comparing
the FMS trajectory with the ground trajectory in order to detect
discrepancies in the latitude and longitude information that
defines the 2D route. Trajectory comparison is done by a computer
executing instructions that perform cusp-to-cusp differencing
consisting of the following steps: (i) Selecting a portion (or one
or more portions) of trajectory where synchronization is desired
(the complete trajectory may not be subject to synchronization, for
instance if the flight is leaving the controlled airspace); (ii)
Calling T1 the FMS trajectory, calling T2 the ground trajectory;
(iii) Traversing T1 in cusp order, for each cusp perpendicularly
project the 2D position of the cusp on T2 (if there is no
perpendicular projection then selecting the nearest point as the
`projection` point); (iv) Computing the 2D distance between the
cusp and the projection point; (a) If the distance is greater than
a threshold, then flagging this cusp as discrepant; (b) Repeating
for all cusps of T1; (c.) Repeating the above steps but his time
traversing T2; (d) Reporting the discrepant cusps.
Further in step 450, verification of restriction compliance is made
by insuring that the FMS trajectory (aircraft trajectory) complies
with altitude and speed restrictions.
In step 460, instructions are assembled in order to correct for
discrepancies detected in step 450 and restriction violations
identified in step in step 450; this instructions may be
communicated to the operator (pilot or Airline Operations Control
Center AOCC) via established air-ground communication systems such
as CPDLC.
In step 470, the FMS system applies the changes identified in step
460 and produces a new FMS 4DT. This new 4DT is pushed to the
ground system for processing. The air system down link the FMS
trajectory to the ground system.
In step 480, the ground receives from the aircraft (FMS) a
four-dimensional trajectory (4DT) in space (latitude, longitude,
altitude) and time. Given that the main sources of discrepancies
expected between the FMS-generated trajectory and the ATC-generated
trajectory may be the rates of change in the altitude and speed
during takeoff, initial climb, descent, final approach and landing
(i.e. the vertical profile), the downlink of the aircraft 4DT may
provide the information needed on the ground for reconstruction of
realistic alternative trajectories, if needed.
Continuing with step 480, the ground system may build a trajectory
using FMS trajectory cusps. An approach to build the synchronized
ground trajectory may be to insert cusps with the same geographic
location, altitudes and times as those found in the FMS trajectory;
two alternatives may be used to set the speeds and accelerations,
depending on the available data in the FMS trajectory: The ground
computers in the ATC perform the following instructions to build a
synchronized trajectory: (1) Approximate the segments to be of
constant speed as implied by the segment length and duration (the
effective average ground speed is equal to the segment length
divided by the segment duration); and (2) Compute the acceleration
based on the point and wind velocities provided in the FMS
trajectory (for instance as specified in the ARINC.RTM. 702A
standard). For each trajectory segment that is being built the
acceleration a can be derived, assuming that it is constant, using
the true air speed (TAS) at the beginning of the segment, the wind
speed, the duration of the segment T and the length of the segment
L: a=2*(L-v*T)/(T*T), where v is the ground speed computed as the
vector sum of the true air speed and wind speed; alternatively
(because the system is over-determined) the acceleration can be
directly computed using the ground speed at the beginning of the
segment v0, the ground speed at the end of the segment v1 and the
duration of the segment T: a=(v1-v0)/T. If the acceleration is
truly constant then these two are equivalent. The errors involved
in these two approaches may depend on segment duration, therefore
means should be provided to allow in step (d) above for the
insertion of additional trajectory points (arbitrary Lat/Lon
points) so that long segments in the FMS trajectory can be broken
into smaller ones to maintain the required fidelity. Longitudinal
prediction errors may grow with time and may have adverse effects
in functions (such as conflict probe) that depend on trajectories,
therefore: accuracy requirements for these functions may dictate
the maximum tolerances allowed and in turn the maximum segment
length. Segment duration T (or equivalent segment length) can be
controlled to limit the size of the discrepancies between the
ground trajectory and the FMS trajectory, specifically the maximum
longitudinal error within a segment due to non-zero acceleration
(b=change of acceleration within the segment) is equal to
error=2*b*T*T*T/81; the maximum longitudinal error in a segment due
to uncertainty in the air speed at the start of the segment (sv) is
error=sv*T/4; the maximum ground speed error due to assuming
constant acceleration when in reality it is not constant is
error=b*T*T/6; similarly the error in altitude due to vertical
acceleration (ah) is error=ah*T*T/8, T is segment duration.
The steps described below apply for trajectories that have already
passed the first synchronization stage:
In step 490, the trajectories are kept current, fresh, or updated
through an updating module that performs the following steps:
Initial longitudinal (time) re-conformance: as soon as the ground
systems receive a departure or FIR crossing message, the ground
trajectory may be longitudinally re-conformed (cusp times may be
recomputed to be consistent with time information provided). (i)
Conformance monitoring: as the flight progresses, a number of
situations may arise that result in loss of synchronization (for
instance: change in runway assignment, unforeseen wind changes,
errors in wind forecast, tactical intervention by the controller,
weather reroutes, velocity variance due to cost index, etc.). For
this reason, it may be necessary that the ground system checks the
sensed position reports provided by the surveillance system against
the active trajectory and in cases of out of conformance
detections, corrections may be applied to the active trajectory;
this operation may entail a re-synch process consisting of the
steps a through g above. Updating as a result of wind related
forces.
In step 490, trajectory synchronization is needed to compensate for
wind conditions. Air-ground wind model discrepancies may
potentially be an additional source of significant errors leading
to two type of problems: (1) a synchronized trajectory going out of
conformance repeatedly in short time intervals, thus triggering
multiple re-synch operations, and (2) an aircraft flying a conflict
free synchronized trajectory encountering a real conflict
(unpredicted because of wind discrepancies) in the future that will
cause tactical intervention and thus nullify the benefits of
synchronization (and possibly even introduce penalties). Errors in
wind data and discrepancies in wind models between air-ground
systems may result in longitudinal errors (s.sub.x) that grow with
prediction time (T) as s.sub.x=T s.sub.v, where s.sub.v=ground
speed error and could become a significant source of error.
Discrepancies in wind forecasts may result in invalid conflict
probe predictions. Using FMS wind data in the ground system may not
be an option because conflict predictions of neighboring aircraft
using different wind data would result in false or missed alerts.
Conflict probe may require the wind model to be consistently
applied to all aircraft. If the wind data used by the FMS is made
available as part of the FMS trajectory down-link (as provided in
the ARINC.RTM. 702A specification), the ground system may check for
consistency of wind models. If in addition to the FMS wind data
there is also a wind model age (time since forecast was computed)
or wind accuracy (figure of merit) information, the ground system
may assess the reliability of the wind data used by the FMS.
Accordingly, if the ground systems deems that the wind data used by
the FMS is stale or unreliable then the ground system may up-link
new wind data to the aircraft to be used by the wind blending
algorithms in the FMS; on the other hand if the wind data in the
FMS is "fresh" and if there is a significant discrepancy (i.e.
large relative to intrinsic wind models errors), then the ground
system may add prediction buffers to account for larger prediction
errors (conflict probe, for instance, can be performed adding a
buffer to accommodate the uncertainty in speed).
The disclosed embodiments meet the need in the art to provide a
solution to the problems of conventional systems for the following
reasons: (a) The disclosed embodiments may take into account user
preferences: by using the (restriction compliant and laterally
synchronized) down-linked FMS trajectory to build the ground
trajectory all of the optimization choices made by the FMS to build
its own trajectory, may be automatically incorporated in the ground
system (for instance if the FMS modeled an optimized descent, the
vertical profile in the ground system may reflect such
optimization). (b) By exchanging a combination of aircraft intent
(AI) data and trajectory data, the disclosed embodiments may solve
the problems associated with the individual limitations associated
with each one of these data items (as described in the previous
item). (c) The trajectory synchronization of the disclosed
embodiments may be highly dynamic and thus allows for required
adjustments that arise in realistic situations. (d) The disclosed
embodiments may build on current or planned technologies and
concepts (CPDLC, data comm., ARINC 702A, RTCA SC-214, etc), and may
thus allow for an initial implementation in a mixed equipage
environment and a smooth evolution of the ATC system towards
TBO.
FIG. 5 is a block diagram of a in-flight trajectory synchronization
in accordance to an embodiment. In action 505, ANSP establishes
ADS-C contract wherein ANSP starts with pre-departure synchronized
trajectory.
In action 510, surveillance data may also be captured to aid in
trajectory creation.
In action 515, ANSP detects critical event (take-off, facility
entry, first surveillance report, top-of-climb reached,
top-of-descent reached).
The information from action 515 is then used by action 580 so that
ground TP can perform longitudinal (time) re-conformance of
previously synchronized trajectory. In action 590, the
re-conformance is used to verify compliance of trajectories. The
result of the verification is sent to action 592 for further
processing.
The initial trajectory, action 505, is sent from the aircraft 50 in
accordance with the ADS-C contract request, other ground automation
components that use the trajectory (action 535-545), and Air
Traffic Service Provider (action 515).
The aircraft 50 performs processing of the initial trajectory to
produce 4DT ADS-C periodic or on-demand report (Action 520), ADS-C
event report (step 525), and clearance request (step 530).
In step 535, the initial trajectory is used by a schedule
management module to generate a meet time advisory.
In step 540, the initial trajectory is used by a conflict
prediction and resolution module to generate a conflict avoidance
clearance or by a TFM to generate a new constraint.
In step 545, the initial trajectory is used by a conformance
monitoring function checks for deviations of flight from cleared
path.
Steps 520, 525, 530, 535, 540, 545 are processed in step 550 to
determine a sync trigger event. If a sync triggering event is
discovered in step 560 control is passed to action 560 for further
processing.
In step 560, Verify that FMS 4DT complies with ATC restrictions,
verify that converted route of flight in FMS and ground TP agree,
and ANSP coordinates clearance across ATC facilities. If the
discrepancies are discovered in step 560 and 570 a message is
generated requesting modification of the trajectory. Step 592 a
messages to make corrections to FMS 4DT are generated and sent to
aircraft in the event of discrepancies (step 560) or failure to
verify compliance (step 590).
In step 595, aircraft 50 applies changes and builds a new FMS 4DT
and Aircraft 50 down-links FMS 4DT. In action 598, ground TP
performs weather verification and ground TP builds synchronized
trajectory from the FMS 4DT.
FIG. 6 is a flowchart of a method for trajectory synchronization in
accordance to an embodiment. Method 600 begins with step 610 where
the trajectory synchronization module/system receives trajectories
from and FMS and ATC. The method in step 620 identifies
discrepancies and restriction violations from the received
trajectories. A discovered discrepancy or violation from step 620
causes the method to assemble and generate instructions in step
630. In action 640, instructions are applied and a new trajectory
is created that remedy the discrepancies. In action 650, a
4D-trajectory (4DT) is generated. The generated trajectory from
step is propagated to or exchange with other systems (ATC, ATM, and
etcetera) in step 660. The method waits for updates (triggering
events) that would require changes to the 4DT of step 660. The
Updates of step 670 are sent to 610 for further processing in
accordance to method 600.
Embodiments within the scope of the present disclosure may also
include computer-readable media for carrying or having
computer-executable instructions or data structures stored thereon.
Such computer-readable media can be any available media that can be
accessed by a general purpose or special purpose computer. By way
of example, and not limitation, such computer-readable media can
comprise RAM, ROM, EEPROM, CD-ROM or other optical disk storage,
magnetic disk storage or other magnetic storage devices, or any
other medium which can be used to carry or store desired program
code means in the form of computer-executable instructions or data
structures. When information is transferred or provided over a
network or another communications connection (either hardwired,
wireless, or combination thereof) to a computer, the computer
properly views the connection as a computer-readable medium. Thus,
any such connection is properly termed a computer-readable medium.
Combinations of the above should also be included within the scope
of the computer-readable media.
Computer-executable instructions include, for example, instructions
and data which cause a general purpose computer, special purpose
computer, or special purpose processing device to perform a certain
function or group of functions. Computer-executable instructions
also include program modules that are executed by computers in
stand-alone or network environments. Generally, program modules
include routines, programs, objects, components, and data
structures, etc. that perform particular tasks or implement
particular abstract data types. Computer-executable instructions,
associated data structures, and program modules represent examples
of the program code means for executing steps of the methods
disclosed herein. The particular sequence of such executable
instructions or associated data structures represents examples of
corresponding acts for implementing the functions described in such
steps.
Although the above description may contain specific details, they
should not be construed as limiting the claims in any way. Other
configurations of the described embodiments of the disclosure are
part of the scope of this disclosure. For example, the principles
of the disclosure may be applied to each individual user where each
user may individually deploy such a system. This enables each user
to utilize the benefits of the disclosure even if any one of the
large number of possible applications do not need the functionality
described herein. In other words, there may be multiple instances
of the components each processing the content in various possible
ways. It does not necessarily need to be one system used by all end
users. Accordingly, the appended claims and their legal equivalents
should only define the disclosure, rather than any specific
examples given.
The attached materials provide further details of the disclosure,
as set forth below:
* * * * *