CALVO-FERNÁNDEZ ET AL.
Downloaded by UNIV. OF ARIZONA on March 14, 2017 | http://arc.aiaa.org | DOI: 10.2514/1.G000691
set of resolutions, i.e., the set of deviations, with respect to the flight
plan, used to solve the conflicts, either vertically or temporally; and
3) the likelihood of each resolution occurring.
D.
Application of the Conflict-Resolution Model to Planning in the
Strategic Phase
In this section, the conflict-resolution model is applied to the
conflicts detected in the strategic phase. First, we detected the
conflicts in the flight plans that were in the SBT phase.
We then applied the method of pairwise comparison [6] to resolve
the conflicts in the maneuvers obtained from the conflict-resolution
model. In this way, the flight plans of each aircraft involved in a
conflict were modified. This resulted in a set of potential resolutions:
in other words, alternative flights plans for each affected flight, which
will be assessed later on.
1.
Temporal (Speed) Conflict Resolution
Temporal resolution consists of either advancing or delaying the
time at which a flight will pass over the point where a conflict is
detected. This is illustrated in Fig. 8, where the times of the actual
flight plan (conflicted) are shown, as well as the times of the new
flight plan (after applying the temporal resolution). In Fig. 8, the start
and end times of the conflict are represented by t
i
and t
f
. In the
example given, the conflict will be solved temporally if the new flight
plan arrives at the points, where the conflict is detected, which is
2 min earlier than the time specified in the actual flight plan.
There were a number of restrictions in the temporal resolutions:
1) The cruise phase entry and exit times (t
n
and t
x
in Fig. 8) are
constant. This means that, if a conflict is solved by delaying its arrival at
the conflict point, the aircraft will reduce its speed in the phase before
the conflict (to arrive later) and will increase its speed afterward (to
compensate for the delay and ensure that the exit time is constant).
2) All the speeds established in the new flight plan must be valid
according to the Base of Aircraft Data (BADA) 3.6 [39]; otherwise,
the proposed trajectory will be deemed invalid.
2.
Vertical Conflict Resolution
Vertical conflict resolution consists of either increasing or decreasing
the cruise altitude. This is illustrated in Fig. 9, where the cruise
altitude of the actual flight plan (conflicted) and the cruise altitude of
the new flight plan (after applying the vertical resolution) are shown.
There were a number of restrictions in the vertical resolutions:
1) The rates of climb or descent established in the new flight plan
were extrapolated from the original flight plan.
2) All the cruise altitudes h
0
CR
established in the new flight plan
must be valid according to BADA 3.6 [39]; otherwise, the proposed
trajectory will be deemed invalid.
By applying the model to the conflicts detected in the strategic
phase, we obtained a set of potential resolutions for each conflict.
This set of resolution contains all the possible vertical and temporal
resolutions, provided by the implemented data-driven model, for
each aircraft involved in a conflict. The model also calculated the
following information for potential resolutions:
1) The model calculated the likelihood of the resolution being
implemented by the controller. The higher the likelihood, the more
probable it was that the proposed action would be carried out.
2) The model calculated the additional fuel consumed by applying
the proposed resolution, as per the BADA Aircraft Performance
Model [39]. This value may be negative; in which case, the new
trajectory will consume less fuel than the original one.
3) The model calculated the possibility of successfully
implementing a specific resolution. This was calculated based on
aircraft performance. If the new trajectory was invalid, it was not
considered as a potential optimal solution.
The model also checked to see if the proposed new trajectory was
free of conflicts with all other aircraft. Otherwise, it was not
considered as a potential optimal resolution.
E.
Multiobjective Optimization of Proposed Solutions
In the previous section, the conflict-resolution model was applied to
individual conflicts that were detected at the strategic planning phase and
resulted in a set of potential resolutions for each conflict. In this section,
Table 1
Breakdown of conflicts per
flight phase
% Conflicts
Aircraft in the same phase
Climb
1.2
Cruise
64.3
Descent
19.8
Aircraft in different phases
Climb
–cruise
4.9
Climb
–descent
1.4
Cruise
–descent
8.5
Chia sẻ với bạn bè của bạn: