Method and device for piloting an aircraft about a piloting axis
View Patent ↗The flight-control device ( 1 ) makes it possible, by offsetting part of a flight command according to a particular flight path, to obtain the same control as is obtained with usual flight control, but without flexible excitation that generates discomfort in the aircraft.
1. A method for piloting an aircraft about a piloting axis, said aircraft comprising a plurality of N controllable aerodynamic surfaces that produce a movement of the aircraft about said piloting axis, the method comprising the steps of:
a) producing an overall piloting command relating to said piloting axis;
b) determining individual control commands based on the overall piloting command;
c) converting each individual control command to an individual piloting command; and
d) actuating, according to the individual piloting command, at least one of said N controllable aerodynamic surfaces to pilot the aircraft about said piloting axis,
wherein
each individual control command is determined by multiplying said overall piloting command by at least one gain Ki which is positive or negative, with i being an integer of from 1 to N, N being an integer greater than 1, with the sum of all gains represented by:
∑
i
Ki
=
N
;
wherein the sum of all gains reduces excitation of N-1 flexible modes of the aircraft, with the N-1 flexible modes representing a current value function of parameters related to the aircraft, and with said N individual piloting commands being obtained by solving a linear system of N-1 equations with N unknowns,
and wherein the individual piloting commands are converted to the individual control commands on the basis of positive gains Ki.
2. The method as claimed in claim 1 , wherein:
the gains Ki are such that the sum
∑
i
Ki
is equal to zero; and
the individual control commands produce the following overall effect Effg:
Effg
=
∑
j
Kj
·
Eff
(
t
)
,
j being the integers i for which the corresponding gains Kj are positive, and Eff(t) being the command that would be dispatched in an equal manner to the N aerodynamic surfaces ( 2 A to 2 N) to obtain the overall effect N.Eff(t); and
after a predetermined duration T, the individual control commands produce the following overall effect Effg:
Effg
=
∑
j
Kj
·
Eff
(
t
)
+
∑
l
Kl
·
Eff
(
t
-
T
)
l being the integers i for which the corresponding gains Kl are negative.
3. The method as claimed in claim 1 , wherein:
the gains Ki are such that the sum
∑
i
Ki
is different from zero; and
the individual control commands produce the following overall effect Effg:
Effg
=
KA
·
∑
j
Kj
·
Eff
(
t
)
,
j being the integers i for which the corresponding gains Kj are positive, Eff(t) being the command that would be dispatched in an equal manner to the N aerodynamic surfaces ( 2 A to 2 N) to obtain the overall effect N.Eff(t), and KA being a gain which satisfies the following relation:
KA
·
∑
j
Kj
=
N
after a predetermined duration T, the individual control commands produce the following overall effect Effg:
Effg
=
[
KA
·
∑
j
Kj
·
Eff
(
t
)
]
-
[
KB
·
∑
j
Kj
·
Eff
(
t
-
T
)
]
+
[
(
KA
+
KB
)
·
∑
l
Kl
·
Eff
(
t
-
T
)
]
l being the integers i for which the corresponding gains Kl are negative, and KB being a gain which satisfies the following relation:
[
(
KA
-
KB
)
·
∑
j
Kj
]
+
[
(
KA
+
KB
)
·
∑
l
Kl
]
=
N
4. The method as claimed in claim 1 , wherein said piloting axis is the roll axis of the aircraft which is fitted with two wings, said aerodynamic surfaces are ailerons which are mounted on said wings, and N is the number of ailerons.
5. The method as claimed in claim 1 , wherein said piloting axis is the yaw axis of the aircraft, and said aerodynamic surfaces are rudders of said aircraft.
6. A device for piloting an aircraft about a piloting axis, said aircraft comprising a plurality of N controllable aerodynamic surfaces that produce movement of the aircraft about said piloting axis, said device comprising:
pilot command unit that produces an overall piloting command relating to said piloting axis;
individual control units that determine, on the basis of the overall piloting command, individual control commands corresponding to each of said N controllable aerodynamic surfaces
actuators that apply said individual control commands to actuate said aerodynamic surfaces,
wherein:
said individual control units comprise individual pilot command units that produce, on the basis of said overall piloting command, N individual piloting commands relating respectively to said N aerodynamic surfaces, by multiplying said overall piloting command by at least one gain Ki which is positive or negative, i being an integer of from 1 to N, and N being an integer greater than 1, with the sum of all gains represented by:
∑
i
Ki
=
N
;
and wherein the sum of all gains reduces excitation of N-1 flexible modes of the aircraft, with the N-1 flexible modes representing a current value function of parameters related to the aircraft, and with said N individual piloting commands being obtained by solving a linear system of N-1 equations with N unknowns; and
said individual control units comprise conversion units that convert said individual piloting commands to said individual control commands,
wherein
said actuators actuate corresponding aerodynamic surfaces,
and wherein the individual piloting commands are converted to the individual control commands on the basis of positive gains Ki.
7. An aircraft, comprising the device of claim 6 .