U.S. patent application number 10/703564 was filed with the patent office on 2005-01-27 for fly-by-wire control system for an aircraft comprising detection of pilot induced oscillations and a control for such a system.
Invention is credited to Fabre, Pierre, Gautier, Jean-Pierre, Raimbault, Nathalie, Sagansan, Alain.
Application Number | 20050021193 10/703564 |
Document ID | / |
Family ID | 32116638 |
Filed Date | 2005-01-27 |
United States Patent
Application |
20050021193 |
Kind Code |
A1 |
Raimbault, Nathalie ; et
al. |
January 27, 2005 |
Fly-by-wire control system for an aircraft comprising detection of
pilot induced oscillations and a control for such a system
Abstract
Fly-by-wire control system for an aircraft comprising detection
of pilot induced oscillations and a control for such a system.
According to the invention, provision is made for the pivotings of
said control (2) to be damped by controllable damping means (15,
16) controlled by means (7) detecting oscillations corresponding to
pilot induced oscillations.
Inventors: |
Raimbault, Nathalie;
(Toulouse, FR) ; Gautier, Jean-Pierre; (Toulouse,
FR) ; Sagansan, Alain; (Colomiers, FR) ;
Fabre, Pierre; (Toulouse, FR) |
Correspondence
Address: |
STEVENS, DAVIS, MILLER & MOSHER, L.L.P.
Suite 850
1615 L Street, N.W.
Washington
DC
20036
US
|
Family ID: |
32116638 |
Appl. No.: |
10/703564 |
Filed: |
November 10, 2003 |
Current U.S.
Class: |
701/4 |
Current CPC
Class: |
G05D 1/0816
20130101 |
Class at
Publication: |
701/004 |
International
Class: |
G06F 007/00 |
Foreign Application Data
Date |
Code |
Application Number |
Nov 18, 2002 |
FR |
02 14388 |
Claims
1. A fly-by-wire control system involving electric flight commands
for an aircraft, comprising: a mobile control able to generate at
least one electric command for controlling said aircraft about at
least one of its axes of maneuver; and means for detecting, in said
command, any oscillations corresponding to pilot induced
oscillations, wherein said control comprises controllable damping
means able to damp the movements of said control and wherein said
detection means control said controllable damping means in such a
way that these exert on said control an action that opposes the
rate of travel of the latter when said detection means detect such
oscillations.
2. The system of flight controls as claimed in claim 1, wherein the
action of said controllable damping means on said control is of an
amplitude that is constant irrespective of the amplitude of said
oscillations.
3. The system of flight controls as claimed in claim 1, in which
said detection means deliver a detection signal the amplitude of
which increases with the amplitude of said oscillations, wherein
the action of said controllable damping means on said control
increases in magnitude with the amplitude of said oscillations.
4. A mobile control able to generate at least one electric command
for controlling an aircraft about at least one of its axes of
maneuver, said control being intended for a fly-by-wire control
system comprising means for detecting, in said command, any
oscillations corresponding to pilot induced oscillations, and which
comprises controllable damping means for said control and wherein
said controllable damping means are controlled by said detection
means in such a way that said controllable damping means exert on
said control an action that opposes the rate of travel of the
latter when said detection means detect such oscillations.
5. The mobile control as claimed in claim 4, comprising structural
damping means able to avoid excessively rapid flight-control
movements, wherein said controllable damping means are mounted in
parallel on said structural damping means.
6. The mobile control as claimed in claim 4, comprising structural
damping means able to avoid excessively rapid flight-control
movements and intended for a fly-by-wire control system in which
said detection means are incorporated into the fly-by-wire computer
of said system, wherein said structural damping means and said
controllable damping means are formed of a single controllable
damper controlled by said detection means such that: in the absence
of said oscillations, said single damper performs the function of
said structural damping means; and in the presence of said
oscillations, said single damper performs the function of said
controllable damping means.
7. The control as claimed in claim 4, wherein said controllable
damping means are mechanical or hydraulic.
8. The control as claimed in claim 4, wherein said controllable
damping means are formed by a magnetic machine.
9. The control as claimed in claim 8, wherein said magnetic machine
is a synchronous machine with a permanent-magnet rotor.
10. The control as claimed in claim 4, able to generate two
electric commands for controlling said aircraft about two of its
axes of maneuver and intended for a fly-by-wire control system
comprising means for detecting, in each of said commands, any
oscillations corresponding to pilot induced oscillations, and which
comprises controllable damping means controlled by said detection
means and able to act on said control in its movements
corresponding to each of said commands.
Description
[0001] The present invention relates to a fly-by-wire control
system for an aircraft comprising detection of pilot induced
oscillations, and to a control for such a control system.
[0002] It is known that the controls (sticks, rudder) of modern
aircraft, particularly those known as ministicks, are easy for the
pilot and/or the copilot of said aircraft to handle, it being
possible for them to be tilted very quickly. By contrast, the
actuators operating the moving aerodynamic surfaces of the aircraft
(ailerons, flaps, rudders, etc.) operated from these controls
cannot respond instantly to the electric commands generated by
these controls. There may therefore, at large control amplitudes,
be a significant phase shift between the movement of a control and
the movement of the moving aerodynamic surfaces it controls.
[0003] As a result, the pilot, noticing that the position of the
operated mobile aerodynamic surfaces is lagging behind the position
chosen for said control member, may attempt to further increase the
amplitude by which he tilts said control member. However, the
amplitude of turning of the aerodynamic surfaces may then exceed
that corresponding to the initial command, which means that the
pilot then reduces the tilt of said control member, thus leading,
with a delay, to a return of the aerodynamic surfaces, etc.
Oscillations, caused by coupling and generally referred to in
aeronautical parlance as "pilot induced oscillations" (PIO)
therefore occur in the aircraft and may degrade the precision of
the flying.
[0004] In an attempt at solving this problem, it is known practice
to increase the size of the actuators of the aerodynamic surfaces
controlled and of their electrical and hydraulic supplies, thus
increasing the cost and mass of the aircraft. Such increases in
cost and in mass may become intolerable in the case of large-sized
aircraft.
[0005] Furthermore, document U.S. Pat. No. 4,298,833 envisions the
processing of the command, particularly by filtering it, to convert
it into an order that is free of pilot induced oscillations.
However, this processing is Performed without any true detection of
the pilot induced oscillations and without the knowledge of the
pilot, who may then continue to generate such oscillations.
[0006] The object of the present invention is to overcome these
drawbacks. The invention relates to a fly-by-wire control system
and to a control alerting the pilot to the occurence of pilot
induced oscillation and acting to avoid its effects.
[0007] To this end, according to the invention, the fly-by-wire
control system involving electric flight commands for an aircraft,
comprising:
[0008] a mobile control able to generate at least one electric
command for controlling said aircraft about at least one of its
axes of maneuver (roll, pitch, yaw); and
[0009] means for detecting, in said command, any oscillations
corresponding to pilot induced oscillations,
[0010] is notable in that said control comprises controllable
damping means able to damp the movements of said control and in
that said detection means control said controllable damping means
in such a way that these exert on said control an action that
opposes the travel of the latter when said detection means detect
such oscillations.
[0011] Thus, by virtue of the present invention, should pilot
induced oscillations occur, said control is braked, which alters
the feeling of force felt by the pilot (and therefore alerts the
pilot to the presence of such oscillations) and reduces the phase
shift between the controlled aerodynamic surface and the
control.
[0012] The action of said controllable damping means on said
control may be of an amplitude that is constant irrespective of the
amplitude of said oscillations. However, in the advantageous case
where said detection means deliver a detection signal the amplitude
of which increases with the amplitude of said oscillations (see,
for example, the detector described in the French patent
application filed on Nov. 18, 2002, in the name of the Applicant
Company, under the number 02 14381), the action of said
controllable damping means on said control may advantageously
increase in magnitude with the amplitude of said oscillations.
[0013] The present invention additionally relates to a mobile
control able to generate at least one electric command for
controlling an aircraft about at least one of its axes of maneuver,
said control being intended for a fly-by-wire control system
comprising means for detecting, in said command, any oscillations
corresponding to pilot induced oscillations. According to the
invention, this control, for example of the stick or rudder type,
is notable in that it comprises controllable damping means for said
control and in that said controllable damping means are controlled
by said detection means in such a way that said controllable
damping means exert on said control an action that opposes the rate
of travel of the latter when said detection means detect such
oscillations.
[0014] It will be noted that, in the known way, the controls are
already equipped with structural damping means able to avoid
excessively rapid flight-control movements. The result of this is
that said controllable damping means may be mounted in parallel on
said structural damping means.
[0015] However, particularly when said oscillation detection means
are incorporated into the fly-by-wire computer of said system (see
the aforementioned patent application), it is advantageous for said
structural damping means and said controllable damping means to be
formed of a single controllable damper controlled by said detection
means such that:
[0016] in the absence of said oscillations, said single damper
performs the function of said structural damping means; and
[0017] in the presence of said oscillations, said single damper
performs the function of said controllable damping means.
[0018] Said controllable damping means may be of mechanical or
hydraulic known type.
[0019] However, as a preference, said controllable damping means
are formed by a magnetic machine, for example a synchronous machine
with a permanent-magnet rotor, operated in a known way to deliver a
resistive torque that varies with the rotational speed.
[0020] Of course, particularly when it is of the stick type, said
control may be able to generate two electric commands for
controlling said aircraft about two of its axes of maneuver and be
intended for a fly-by-wire control system comprising means for
detecting, in each of said commands, any oscillations corresponding
to pilot induced oscillations.
[0021] In this case, said control comprises controllable damping
means controlled by said oscillation detection means and able to
act on said control in its movements corresponding to each of said
commands.
[0022] The figures of the attached drawing will make it easy to
understand how the invention can be embodied. In these figures,
identical references denote elements that are similar.
[0023] FIGS. 1 and 2 schematically illustrate two embodiments of
the present invention.
[0024] The fly-by-wire control system for an aircraft, illustrated
schematically in FIG. 1, comprises a control stick system 1, able
to generate a roll command and a pitch command.
[0025] The control stick system 1 comprises a mobile grip 2 which,
via a known mechanism, can pivot about a roll-control axis R-R and
a pitch-control axis T-T.
[0026] The pivoting of the grip 2 about the roll-control axis R-R
(double-headed arrow 3) is detected by a sensor 4. Likewise, the
pivoting of the grip 2 about the pitch-control axis T-T
(double-headed arrow 5) is detected by a sensor 6.
[0027] The sensors 4 and 6 generate electric commands for roll and
pitch, which correspond to the pivotings of the grip 2 and which
are sent to the fly-by-wire computers 7 of said system, via lines 8
and 9 respectively. The computers 7 calculate corresponding turn
commands for controlled aerodynamic surfaces (flaps, ailerons,
rudders, etc.) 10 of said aircraft (not depicted), and via lines
11, send appropriate electric orders to the actuators 12 of these
controlled aerodynamic surfaces 10.
[0028] In a known way, artificial sensation devices 13 and 14
providing the pilot with feedback are mounted on the roll-control
and pitch-control axes. The device 13 consists for example of a
strong scissors mechanism and the device 14 of a strong link
rod.
[0029] Furthermore, according to an important specific feature of
the present invention, the control stick system 1 comprises two
dampers 15 and 16, the damping characteristics of which can be
modified by an electric order. They are, for example, of mechanical
or hydraulic known type. The controllable damper 15 is connected to
the roll axis R-R and the controllable damper 16 is connected to
the pitch axis T-T to damp the rotation of the grip 2 about these
two axes.
[0030] In addition, the fly-by-wire computers 7 incorporate means
for detecting any oscillations, corresponding to pilot induced
oscillations, in the commands originating from the sensors 4 and 6,
these detection means being able to deliver, on respective lines 17
and 18 bound for said dampers 15 and 16, orders to modify the
damping characteristics of these dampers according to the amplitude
of said induced oscillations.
[0031] The way in which the system of FIG. 1 works is as
follows:
[0032] when the pilot (not depicted) actuates the grip 2 by tilting
it in such a way that the roll (and/or pitch) command from the
sensor 4 (and/or from sensor 6) is free or almost free of pilot
induced oscillations, the detection means of the flight computers 7
send the damper 15 (and/or 16), via the line 17 (and/or 18), an
electric command setting its damping characteristic to the desired
value so that said damper performs its usual function of structural
damper of the stick system 1;
[0033] by contrast, when the action of the pilot on the tilting
grip 2 generates an induced oscillation in the roll (and/or pitch)
command originating from the sensor 4 (and/or the sensor 6), the
detection means of the flight computers 7 send the damper 15
(and/or the damper 16), via the line 17 (and/or 18), an electric
command to harden its damping characteristic, this hardening being
either constant, or increasing in magnitude with the amplitude of
said oscillations. The pivotings of the grip 2 are therefore then
braked.
[0034] In the alternative form of embodiment that is FIG. 2, we
again see the same elements 2 to 14 as described with reference to
FIG. 1. However, in the case of FIG. 2, the control stick system 20
comprises electric dampers 21 and 22 in place of the mechanical or
hydraulic dampers 15 and 16. The dampers 21 and 22 are, for
example, synchronous machines the rotor of which carries permanent
magnets and is wedged on the axis R-R or the axis T-T,
respectively.
[0035] Thus, the resistive torque exerted by these synchronous
machines on said axes can be controlled by electric commands
generated by the means for detecting said oscillations belonging to
the computers 7 and sent to said dampers 21 and 22 via lines 23 or
24 respectively.
* * * * *