Note: Descriptions are shown in the official language in which they were submitted.
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VEHICLE CAPABLE OF BEING SUBMERGED COMPRISING A MAST
The field of the invention is that of marine vehicles intended to move
submerged in a liquid, notably underwater vehicles. It relates more
particularly to underwater vehicles.
It relates notably to unmanned vehicles also referred to as UUVs
(Unmanned Underwater Vehicles, which may autonomous vehicles also
referred to as AUVs (Autonomous Underwater Vehicles) or non-autonomous
vehicles also referred to as ROVs (Remotely Operated Vehicles).
Underwater vehicles have regularly to return to the surface for various
reasons (to resupply with energy, to communicate with a high transmission
bit rate, to be recovered, take measurements, etc.).
These underwater vehicles therefore comprise a payload comprising
for example a telecommunications antenna or a camera intended to be used
.. above the surface of the water. The underwater vehicle therefore needs to
be
capable of bringing this payload to a sufficient height above the surface of
the
water, often several meters above the surface of the water so as, so as to
allow correct operation of the payload. It is desirable for example to emit
and/or receive radioelectric waves with good performance or to acquire high-
quality images of a landscape situated above the surface of the water.
Furthermore, certain applications require a mast orientation that is as stable
as possible along a vertical axis that is fixed with respect to the
terrestrial
frame of reference.
The payloads such as antennas are generally installed at the end of a
deployable mast which is stowed when the underwater vehicle is traveling at
depth and which is deployed when the vehicle rises back up toward the
surface of the water, so as to bring the payload above the surface of the
water to a sufficient height.
In large underwater vehicles, a mast extending along a radial axis of
the body of the underwater vehicle is provided. The radial axis is defined
with
respect to a longitudinal axis of a body of the underwater vehicle. The body
of the underwater vehicle is elongate along the longitudinal axis. In a
retracted configuration, the mast is folded inside the body of the underwater
vehicle. That makes it possible to limit the hydrodynamic drag of the
underwater vehicle when it is traveling fully submerged. In order to place the
payload above the surface of the water, the underwater vehicle surfaces and
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the mast is translated along the radial axis so as to extend above the body of
the underwater vehicle along a vertical axis. The stability of the mast is
obtained by the inertia of the assembly and by virtue of a vehicle length that
is greater than the length of the waves. Vehicles of a smaller size (of around
one hundred kg, equipped with a payload weighing a few kg at the end of a
mast of several meters) using this type of mast are highly unstable as soon
as there is a little swell. This is because the vehicle floating on the
surface of
the sea follows the surface of the water and experiences a rolling and
pitching movement. If use of the payload incorporated into the mast requires
a certain stability of the mast then its performance is dependent on the sea
state.
Solutions for improving the stability of the mast consist in providing
means for varying the pitch (longitudinal attitude) of the body of the
underwater vehicle so as to allow the longitudinal axis of the body of the
underwater vehicle to be oriented in a substantially vertical direction when
the underwater vehicle is floating on the surface of the water in a
configuration. A first solution of this type is described in patent
application GB
2 335 888 and depicted in figure 1. The mast 1 equipped with the payload
extends vertically above the surface S of the water and is aligned with the
longitudinal axis xe of the body 3 of the underwater vehicle 4. In this
solution,
the mast 1 extends longitudinally substantially along the longitudinal axis xe
of the body 3 of the underwater vehicle 4 and is mobile in translation along
this axis so as to be able to be retracted, inside the body 3 of the
underwater
vehicle 4 vehicle, or deployed outside the body of the underwater vehicle, as
depicted in figure 1, toward the front of the body 3. The pitch of the body 3
of
the underwater vehicle 4 is modified by the translational movement of a mass
5 internal to the body 3 of the underwater vehicle 4 along the longitudinal
axis
xe or using control surfaces.
A second solution is described in patent application US 20080132130
and is depicted in figure 2. In this solution, a first mast 100 equipped with
the
payload is connected to the body 102 of a floating vehicle by a first pivot
connection 103 of axis perpendicular to the longitudinal axis xl of the body
of
the floating vehicle and positioned near a first longitudinal end 104 of the
body 102 of the floating vehicle. A second mast 105 is connected to the body
102 of the floating vehicle by a second pivot connection 106 of axis parallel
to
that of the first pivot connection 103 and positioned close to the second
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longitudinal end 107 of the body of the floating vehicle. This second mast 105
deploys in such a way as to alter the position of the center of gravity of the
underwater vehicle along the longitudinal axis xl of the body of the floating
vehicle in order to vary the pitch of the body 102 so as to bring the vehicle
into a stable position in which it floats at the surface of the water with the
two
masts 100, 105 and the body 102 of the underwater vehicle all vertical as
depicted in figure 2. Control surfaces also allow the pitch of the body of the
floating vehicle to be modified.
Certain applications defined in the context of the invention require the
mast, stabilized in a substantially vertical direction, to be made to rotate
on
itself in the steady state, for example in order to acquire or transmit
information in various directions that are radial with respect to a vertical
axis.
It may for example be necessary to make a radioelectric antenna rotate
about a vertical axis that is fixed with respect to the terrestrial frame of
reference in order to bring it to a correct orientation that allows it to
communicate with another antenna or, when the antenna is a receive
antenna, in order to determine a direction of a source about the vertical axis
by determining the direction in which the received signal is strongest. It may
also be necessary to capture images or acquisitions or emissions of
radioelectric signals over 360 about a fixed vertical axis.
Now, the solutions depicted in figures 1 and 2 do not allow these
functions to be performed.
It is an object of the invention to limit at least one of the
aforementioned disadvantages.
To this end, one subject of the invention is a marine vehicle able to be
submerged, comprising a body extending longitudinally along an axis x and a
mast extending longitudinally along an axis xm, the mast being equipped with
a payload intended to be used above the surface of the water, the marine
vehicle being capable of being in a panoramic configuration in which the
mast extends at least partially above the surface of the water and extends
longitudinally in a substantially vertical direction, the mast being in an
operational configuration in which it extends beyond the body along the axis
x, the marine vehicle comprising a thruster able to generate a torque about
the axis xm, when the marine vehicle is in the panoramic configuration, so as
to cause the body and the mast to rotate about the axis xm.
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Advantageously, the thruster and the mast are arranged in such a way
that when the axis xm is inclined with respect to the axis x in the panoramic
configuration, there is a non-zero lever arm between the axis xm and the
thruster.
Advantageously, the thruster comprises two contrarotating propellers
each comprising blades of which the collective and cyclic pitch about a
neutral position is variable, the propellers being mounted on the body in such
a way as to have the same axis of rotation that is fixed with respect to the
body, this axis of rotation being substantially parallel to the longitudinal
axis
x.
Advantageously, the mast is connected to the body by a pivot
connection allowing the mast to be pivoted with respect to the body between
a stowed configuration in which the mast is folded down along the body and
the operational configuration.
Advantageously, the mast is able to be immobilized in the operational
configuration.
Advantageously, in the stowed configuration, the axis xm extends
substantially parallel to the axis x.
Advantageously, the marine vehicle is able to exhibit positive
buoyancy in a panoramic configuration referred to as a stabilization
configuration in which the body is fully submerged.
Advantageously, the marine vehicle is capable of exhibiting positive
buoyancy in a panoramic configuration referred to as stabilization
configuration in which the body is fully submerged, the mast breaking the
surface of the water.
Advantageously, the marine vehicle has a cross section that is smaller
than a cross section of the body.
Advantageously, the mast is connected to the body by a pivot
connection.
Advantageously, the pivot connection is positioned close to a first
longitudinal end of the body.
Advantageously, the vehicle comprises rotation means configured to
implement, on receipt of a rotation command, a rotation step during which the
thruster generates a torque about the axis the axis xm in order to cause the
body and the mast to rotate about the axis xm, the marine vehicle being in a
panoramic configuration.
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Advantageously, the rotation means are configured to implement the
rotation step when the axis x is inclined with respect to the axis xm.
The invention also relates to a method for controlling a marine vehicle
as claimed in any one of the preceding claims, comprising a rotation step,
during which the thruster generates a torque about the axis the axis xm in the
panoramic configuration, so as to cause the body and the mast to rotate
about the axis xm.
Advantageously, the method comprises a step of adjusting the
buoyancy, prior to the rotation step, in order to bring the marine vehicle
into a
if) condition such that the vehicle exhibits positive buoyancy in the
panoramic
configuration.
Advantageously, the adjustment step is performed in such a way that
the body is fully submerged in the panoramic configuration, with the mast
breaking the surface of the water.
Advantageously, the method comprises a step of deploying the mast,
prior to the rotation step, from a stowed configuration in which the mast is
folded down along the body of the marine vehicle, into the operational
configuration by pivoting the mast with respect to the body about a pivot
connection connecting the mast to the body.
Advantageously, the method comprises a step of regulating the pitch
of the body of the marine vehicle, prior to the rotation step, so that the
axis
xm is substantially vertical in the panoramic configuration.
The invention will be better understood with studying a number of
embodiments described by way of nonlimiting examples and illustrated by
attached drawings in which:
- figure 1, already described, schematically depicts one example of an
underwater vehicle according to the prior art,
- figure 2, already described, schematically depicts one example of a
floating vehicle according to the prior art,
- figure 3 schematically depicts a marine vehicle according to the
invention in a panoramic configuration, the mast being in an operational
configuration,
- figure 4 schematically depicts the marine vehicle of figure 3 in which
the mast is in a stowed configuration,
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- figure 5 schematically depicts the components of one example of a
marine vehicle according to the invention.
From one figure to another, the same elements are denoted by the
same numerical references.
The invention notably relates to an underwater vehicle 10 as depicted
in figure 3. An underwater vehicle is a submersible vehicle capable of moving
under the water, namely when completely submerged. The invention also
applies to a surface vehicle, namely to a floating vehicle intended to float
on
the surface of the water and not intended to be fully submerged, namely
exhibiting positive buoyancy.
The invention will be described hereinafter with reference to an
underwater vehicle but applies to any marine vehicle.
The underwater vehicle 10 comprises a body 11 extending
longitudinally along a longitudinal axis x and a mast 12 connected to the body
11 of the underwater vehicle. The mast 12 is equipped with a payload 13
intended to be used above the surface S of the water.
The payload 13 comprises at least one transmitter and/or at least one
receiver. The payload may comprise a transmitter able to transmit
radioelectric waves or a radioelectric transmission antenna and/or receiver
able to receive radioelectric waves or a radioelectric receive antenna and/or
receiver able to receive light waves or an image sensor and/or an image or
light-ray emitter.
Advantageously, the payload 13 or at least one transmitter and/or at
least one receiver of the payload 13 is attached to the mast 12.
This rotation is achieved using the thruster.
The payload or at least one transmitter and/or at least one receiver of
the payload 13 may be mounted with the ability to pivot with respect to the
mast about the axis of the mast. The underwater vehicle may comprise an
actuator allowing the payload to be pivoted about the axis of the mast. At
least one transmitter and/or at least one receiver of the payload 13 may be
attached removably to the mast. It is contained for example in a reservoir
able to be attached to the mast and able to be detached from the mast, for
example in order to raise communications equipment above the surface of
the water.
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In the nonlimiting example of the figures, the underwater vehicle
comprises a reservoir 130 fixed, permanently or removably, to one end of the
mast 12 in which the payload 13 is housed. As an alternative, the mast
comprises the reservoir.
The underwater vehicle 10 comprises a body 11 of the underwater
vehicle having a shape that is elongate along a longitudinal axis x of the
underwater vehicle 10. The underwater vehicle is for example intended to
move chiefly along the longitudinal axis x.
The mast 12 has a shape that is elongate along a longitudinal axis of
the mast xm.
The mast is capable of being in at least one operational configuration
in which the mast 12 projects with respect to the body 11 of the underwater
vehicle 10 along the axis x. In other words, the mast 12 extends beyond the
body 11 of the underwater vehicle 10 in the operational configuration. In
other words, the vehicle 10 has, in the operational configuration, a
dimension, measured along the axis x, that is greater than the length of the
body 11 of the underwater vehicle because the length of the projection
formed by the mast 12, considered along the axis x, is added thereto. More
specifically, in the operational configuration, the payload 13 or the end of
the
mast closest to the payload 13, extends beyond the body 11 along the axis x.
Advantageously, in the operational configuration, the mast 12 is
secured to the body of the underwater vehicle 10 in terms of rotation about
the axis xm.
The underwater vehicle 10 is able to be in a configuration referred to
as panoramic configuration, an example of which is depicted in figure 3, in
which the mast 12 extends at least partially above the surface of the water
and extends longitudinally in a substantially vertical direction z defined in
a
frame of reference connected with the earth so that the payload is positioned
above the surface of the water, namely so that one end 12a of the mast
extends above the surface of the water. In other words, the longitudinal axis
xm of the mast 12 extends substantially vertically in the panoramic
configuration.
In the panoramic configuration, the mast is in an operational
configuration.
If the mast 12 is able to be in several operational configurations, the
vehicle is advantageously able to be in a configuration referred to as a
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panoramic configuration for each operational configuration of the mast. As an
alternative, the vehicle is able to be in a panoramic configuration for at
least
one operational configuration.
According to the invention, the underwater vehicle 10 comprises a
thruster 14 able to generate a torque about the axis xm so that the body 11 of
the underwater vehicle and the mast 12 can be rotated about the axis xm
when the underwater vehicle 10 is in the panoramic configuration. Thus, the
mast 12 and the body 11 of the marine vehicle 10 rotate about the axis xm,
which is fixed with reference to the terrestrial frame of reference, while
remaining in the panoramic configuration. It is thus possible to perform the
functions described earlier that entail rotating the mast about its axis xm at
a
constant height. Furthermore, because the mast and the body 11 are
secured in terms of rotation about the axis xm, there is no need to provide a
specific device to manage the twisting of the cables connecting the payload
to the body 11 when the mast is rotating about its axis, unlike in a solution
in
which the mast 12 rotates about its axis xm while the underwater vehicle is
fixed with respect to the body of the underwater vehicle. This solution also
makes it possible to avoid installing or using an actuator to cause the mast
to
pivot with respect to the body 11 of the underwater vehicle 10 or to cause the
payload or a transmitter or receiver of the payload to pivot about the axis of
the mast. If such an actuator is provided, the invention allows the panoramic
rotation function to be achieved in the event of a failure of the actuator.
Advantageously, although not necessarily, the thruster 14 is a
vectored-thrust thruster able to generate vectored thrust, namely thrust that
is
orientable with respect to the body 11 of the underwater vehicle 10.
In the remainder of the patent application, a thruster capable of
generating an orientable thrust will be referred to as a vectored thrust
thruster. Vectored-thrust propulsion differs from conventional propulsion in
which the orientation of control surfaces leads to a change in the lift
generated by the stream of fluid surrounding the control surfaces. The force
generated by the fluid on the control surfaces orients the vehicle in the
desired direction. One limitation of this form of propulsion is the need to
generate a significant stream of fluid around the vehicle in order to bring
about a change in lift of the control surfaces to allow a change in direction
of
the vehicle. In other words, it is not possible using conventional propulsion
to
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orient the vehicle in a desired direction without a significant movement of
the
vehicle when the fluid stream is zero.
Vectored thrust propulsion offers numerous advantages, notably
increased maneuverability, simplification of the architecture (e.g. by
eliminating the control surfaces). This capacity for orientation of the
propulsion allows the vehicle to dispense with the conventional control
surfaces used for steering, and therefore to significantly reduce the
hydrodynamic drag of the vehicle thereby making it possible to increase the
endurance of the vehicle.
Advantageously, the thruster 14 is able to generate a thrust directed
along the axis x. This solution makes it possible to avoid installing a
specific
thruster for causing the mast 12 and the body 10 to rotate about the axis of
the mast, the same thruster being able to cause the vehicle to advance along
the axis x and being able to cause it to pivot about the axis xm.
Advantageously, the thruster 14 is an omnidirectional vectored-thrust
thruster. It is able to generate a thrust that can be oriented over 4-rr
steradians.
In the embodiment of the figures, the thruster 14 is mounted on the
body 11 of the underwater vehicle 10. In other words, the thruster 14 is
connected to the mast 12 via the body 11 of the underwater vehicle 10.
In the nonlimiting example of figure 3, the thruster 14 comprises two
propellers 15, 16. Advantageously, these propellers are contrarotating
propellers each comprising blades 17 of which the collective and cyclic pitch
about a neutral position is variable. In the embodiment of the figures, the
propellers 15 and 16 are mounted on the body 11 in such a way as to exhibit
the one same axis of rotation with respect to the body 11 of the underwater
vehicle, this axis of rotation being parallel to the longitudinal axis x of
the
body 11 of the underwater vehicle 10.
As an alternative, the underwater vehicle 10 comprises a thruster 14
able to generate a thrust along the axis x and one or more lateral thrusters
mounted on the body 11 and able to generate a thrust along two orthogonal
radial axes. These lateral thrusters make it possible to generate the desired
torque. The disadvantage with this type of thruster is that when the vehicle
is
advancing along the axis x, these lateral thrusters no longer achieve any
effect because their thrust is "blown away" by the stream generated by the
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forward movement of the vehicle. The vehicle therefore has to be equipped
with control surfaces in order to maneuver it as it advances.
Advantageously, the underwater vehicle 10 is capable of floating,
namely of exhibiting positive buoyancy, in a stable panoramic configuration
like that depicted in figure 3, in which the mast 12 is in an operational
configuration.
When, in the configuration referred to as panoramic configuration, the
underwater vehicle exhibits positive buoyancy, no propulsion energy is
therefore needed in order to keep the underwater vehicle 10 in this
configuration, and this allows the durations of the missions of the underwater
vehicle to be lengthened.
The underwater vehicle 10 may be made to float naturally in this
configuration as a result of its positive buoyancy or may comprise means for
regulating its buoyancy, which means will be described later.
As an alternative, the underwater vehicle 10 may be kept in a
panoramic configuration by the thruster 14.
Advantageously, the thruster 14 (which makes it possible to generate
the desired torque) and the mast 12 are arranged relative to one another in
such a way that when the axis xm is inclined with respect to the axis x in the
operational configuration (non-zero angle a between x and xm) there is a
non-zero lever arm d, namely a non-zero distance, between the axis xm and
the thruster 14. For example, the mast 12 is connected to the body 11 on
which the thruster 14 is mounted by a pivot connection 18 visible in figure 4
arranged some distance from the thruster 14 along the axis x so that the
lever arm increases with the angle a, visible in figure 3, formed between the
axis x and the axis xm. In this way, when the thruster 14 is delivering thrust
generating the torque about the axis xm, there is a non-zero lever arm
between the thrust delivered by the thruster and the axis xm which is inclined
with respect to the axis x. Specifically, this thrust is tangential to a
circle
orthogonal to the axis xm and centered on the axis xm. This configuration
makes it possible to obtain better deployment of the energy of the thruster
during rotation about the axis xm and to generate the torque about xm by
simpler control of the thruster 14, notably in the case of a thruster 14
having
two contrarotating propellers, than when a is zero, the lever arm between the
thruster 14 and the axis xm then being zero. Specifically, in instances in
which the lever arm is zero, namely when the force of the thrust of the
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thruster passes through the axis xm, then the complex means used for
producing rotation about the axis xm is to use the difference in drag produced
on each of the contrarotatory propellers. By increasing or decreasing one or
other of these drags, the residual torque is no longer zero and allows
rotation.
The mast 12 may be able to move with respect to the body 11. The
mast 12 is, for example, connected to the body 11 by an articulation. This
articulation is, for example, a pivot connection 18 with an axis of rotation
substantially perpendicular to the axis x allowing the mast 12 to be made to
pivot with respect to the body 11 between a stowed configuration, depicted in
figure 4, in which the mast 12 is folded down along the body 11 of the
underwater vehicle 10 (the hydrodynamic profile of the mast is thus affected
only little when the mast 12 is in a stowed configuration) and a set of at
least
one operational configuration, of which one is depicted in figure 3. The mast
12 passes from the stowed configuration to the operational configuration by
pivoting about the axis of rotation of the pivot connection 18.
Advantageously, in the stowed configuration depicted in figure 4, the
mast 12 does not project from the body 11 along the axis x. The underwater
vehicle unfolds between the stowed configuration and the operational
configuration. The payload 13 moves away from the body 11 from the stowed
configuration as far as the operational configuration.
Advantageously, like in the stowed configuration depicted in figure 3,
the longitudinal axis xm of the mast 12 (along which the mast 12 extends
longitudinally) extends substantially parallel to the longitudinal axis x of
the
body 11 of the underwater vehicle. The hydrodynamic profile of the
underwater vehicle is thus affected only little in the stowed configuration.
The end of the mast 12 which is furthest from the pivot connection 18
extends beyond the body 11, along the axis x, in the operational
configuration.
The underwater vehicle 10 advantageously comprises an actuator, for
example an actuating cylinder or a rotary motor, for example a stepping
motor, allowing the mast to be pivoted between the stowed configuration and
the operational configuration. The actuator is controlled by a control member.
The mast may for example be able to move between the stowed
configuration in which the axis xm forms a minimum angle a with the axis x,
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and at least one operational configuration in which the axis xm forms a
maximum angle a.
The minimum angle a is advantageously 00 and preferably comprised
between 0 and 5 .
In the present invention, it is desirable to be able to make the mast
rotate about its axis in a panoramic particular configuration in which the
mast
extends vertically and extends at least partially above the surface of the
water and in which the mast is in an operational configuration in which the
mast 12 projects with respect to the body 11 of the underwater vehicle 10
along the axis x. The angle a is greater than 90 in the operational
configuration. Thus, the maximum angle a is greater than 90 and less than
or equal to 180 .
The mast 12 is advantageously able to be immobilized with respect to
the body 11 of the vehicle 10 for a plurality of angles a in the range in
which
it is variable. The mast immobilized at an angle a less than 90 allows the
payload to be positioned above the surface when this vehicle is moving
horizontally along its longitudinal axis. This allows the capabilities of the
payload to be made available during transit.
The mast 12 is advantageously able to be immobilized with respect to
the body 11 of the vehicle in at least one operational configuration.
As an alternative, the mast 12 is fixed with respect to the body 11 of
the underwater vehicle 10 and is in an operational configuration. As an
alternative, the mast 12 is able to move in translation with respect to the
body
of the underwater vehicle, for example along the axis of the mast 12, as
described with reference to document GB 2 335 888, between a stowed
configuration and an operational configuration.
In the embodiment of figure 4, the mast 12 is housed, in the stowed
configuration, on the outside of the body 11. As an alternative, the mast 12
is
housed inside the body 11 in the stowed configuration. The hydrodynamic
profile of the underwater vehicle is then affected less.
Advantageously, the underwater vehicle 10 is capable of floating,
namely of exhibiting positive buoyancy in a panoramic configuration, referred
to as stabilization configuration, as depicted in figure 3, in which the body
11
of the underwater vehicle 10 is fully submerged and in which the mast 12
breaks the surface of the water. Advantageously, a cross section of the mast
is smaller than a cross section of the body 11.
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Advantageously, a cross section, for example a mean cross section of
the mast 12 (considered transversely to the axis xm) between its connection
(for example the articulation 18) to the body 11 and a longitudinal end of the
mast 12 which end is intended to be out of the water in the operational
configuration is less than a cross section, for example, a mean cross section,
of the body 11 of the underwater vehicle (considered transversely to the axis
x). This configuration promotes the stability of the mast 12 which stability
is
obtained because only a small cross section breaks the surface of the water.
In effect, the instability of the mast stems from the variation in upthrust
which
is proportional to the variation in submerged volume resulting from the action
of the waves. Because the cross section of the mast is small (in comparison
with that of the body of the vehicle), the variation in submerged volume
caused by the action of the waves is small and the disturbances experienced
by the mast are small. This then results in far better stability of the mast
when
Out of the water.
As an alternative or in addition, the underwater vehicle 10 may be
capable of floating in a panoramic configuration in which the body 11 of the
underwater vehicle 10 breaks the surface S of the water. This configuration is
not as good for the stability of the mast.
In the embodiment of figures 3 and 4, the mast 12 is connected to the
body 11 of the underwater vehicle 10 by a pivot connection 18 positioned
near a first longitudinal end AV of the body 10 of the underwater vehicle and
is further away from the second longitudinal end AR of the body 10 of the
underwater vehicle 11. This makes it possible to provide a mast 12 of great
length without affecting the hydrodynamic profile of the underwater vehicle in
the stowed configuration and therefore makes it possible to bring the payload
13 to a great height above sea level. Furthermore, that makes it possible to
limit the hydrodynamic drag of the underwater vehicle 10 during submerged
transits by configuring the mast 12 into a stowed configuration with respect
to
the operational configuration.
The thruster 14 is mounted on the body 11 of the underwater vehicle
10, near the second end AR of the body 11 of the underwater vehicle 10.
For greater clarity, the first end AV is referred to as the front end of the
vehicle and the second end AR is referred to as the rear end. The vehicle 11
is intended to move chiefly along the axis x, in the direction from the rear
end
AR toward the front end AV, or exhibits better efficiency in that direction.
The
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thruster 14 is therefore positioned near the rear end AR of the underwater
vehicle.
As a variant, it is conceivable to reverse the layout of the mast 12 and
of the thruster 14 along the axis x.
The underwater vehicle comprises panoramic configuration means
able to implement a panoramic configuration step in which the vehicle is
brought from a non-panoramic configuration into a panoramic configuration.
The panoramic configuration means comprise the means, where
present, of deploying the mast allowing the mast to be brought into an
operation configuration from a stowed configuration.
The panoramic configuration means potentially comprise buoyancy
regulating means allowing the buoyancy of the vehicle to be regulated, so as
to allow the vehicle to be brought into a panoramic configuration of
stabilization. In the case of an underwater vehicle, these buoyancy regulating
means are advantageously configured in such a way as to allow the
underwater vehicle to pass from a fully submerged configuration into a
panoramic configuration of stabilization, an example of which is depicted in
figure 4.
In general, the buoyancy regulating means comprise means for
varying the density of the object or of the underwater vehicle.
The means for varying the density comprise at least one variable-
density reservoir (two reservoirs, a rear reservoir 20 and a front reservoir
21
in the example of figures 3 and 4) the variation in density of which leads to
a
variation in the density of the vehicle. This reservoir has a variable mass
and
a fixed volume (as in the example of figures 3 to 4) or a variable volume the
variation volume of which leads to a variation in the volume of the vehicle,
and a fixed mass. The buoyancy regulating means also comprise means
making it possible to regulate the density of each reservoir. These means
comprise means making it possible to vary the density of each reservoir (rear
valve 22 and front valve 23, pump 29 and actuator 30 in the nonlimiting
example of the figures) and other means for controlling these means (control
member 26).
In the example of figures 3 and 4, the reservoirs 20 and 21 are able to
communicate with the environment in which the underwater vehicle is
immersed so that liquid in which the underwater vehicle is immersed can
circulate between these reservoirs and the marine environment so as to fill
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the reservoirs with or empty the reservoirs of this liquid in order to
increase
its mass. This environment is, for example, the marine environment but could
be any other liquid. In the remainder of the text, reference will be made to
the
marine environment, but the invention is of course applicable to any other
liquid.
The means for regulating the buoyancy of the underwater vehicle have
been depicted schematically in figure 5. The reservoirs 20, 21 are able to
communicate with the marine environment via respective hydraulic
circuits 24, 25 that can be opened or closed by respective front valve 22 and
rear valves 23, the circulation of the water from the marine environment
toward the reservoirs 20, 21 (or vice versa) being brought about by a pump
29 actuated by an actuator 30, for example a motor. The actuator 30 and the
front and rear valves are controlled by a control member 26 to regulate the
masses of the reservoirs 20 and 21 by varying the volume of water contained
in these reservoirs 20 and 21 (by discharging water contained in the
reservoirs into the marine environment, or vice versa).
The means for varying the buoyancy of the vehicle are controlled by a
control member 26 receiving a measurement of a parameter representative
of the buoyancy of the vehicle and generated by a sensor 27, commanding
these means on the basis of this measurement to vary the buoyancy of the
vehicle in such a way that it exhibits a predetermined setpoint buoyancy.
The sensor 27 is, for example, an immersion sensor.
The control member 26 controls the valves and the pump to vary the
masses of the reservoirs 20 and 21 by varying the volume of water contained
in these reservoirs 20 and 21 (by discharging water contained in the
reservoirs into the marine environment, or vice versa) so that the underwater
vehicle exhibits a setpoint submersion received by the control member.
In the nonlimiting embodiment of the figures, the reservoirs 20 and 21
are spaced apart along the axis x. The two reservoirs 20, 21 are therefore
each positioned near one of the ends of the underwater vehicle 1. The
reservoir 21 is positioned near the rear end AR and the reservoir 20 near the
front end AV of the underwater vehicle. As a variant, the buoyancy varying
means comprise a single reservoir or more than two reservoirs.
As a variant, the means for regulating the density comprise at least
.. one reservoir, referred to as external, of variable volume arranged in such
a
way that a variation in the volume of the reservoir leads to a variation in
the
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CA 03085376 2020-06-10
volume of the underwater vehicle. This reservoir communicates for example
with an internal reservoir arranged inside the body of the underwater vehicle
via a valve so as to allow a fluid to be passed from one of the reservoirs to
the other or so as to block the passage of this fluid between the two
reservoirs, a pump causing the fluid to circulate via the valve. An actuator,
for
example a motor, is provided to actuate the pump. This solution leads to
fewer problems with corrosion and reliability than the previous solution at
the
expense of the mass and of the volume of the underwater vehicle. Two
reservoirs may for example be provided, one at each longitudinal end of the
underwater vehicle.
In the embodiment of the figures, the underwater vehicle 10 is
intended to move chiefly along the axis x. As a result, as the mast 12
deploys, the mast 12 forms a projection on the front of the body 11 of the
underwater vehicle 10 along the axis x thereby shifting the center of gravity
of
the underwater vehicle 10 in the direction of the axis x in figure 3. If the
center of volume advances along the axis x by the same distance, the pitch
of the vehicle does not vary. If the center of gravity advances by a longer
distance than the center of volume, then the vehicle tips forward. The rear
end of the vehicle tips down toward the bottom if the center of gravity moves
back along the axis x by a greater distance than the center of volume. In
order to alleviate this disadvantage, the underwater vehicle 10
advantageously comprises means for regulating the pitch of the body 11 of
the underwater vehicle 10.
The panoramic configuration means potentially comprise pitch
regulating means allowing the pitch of the body 11 of the underwater vehicle
10 to be regulated so that the mast can be vertical the panoramic
configuration.
In the nonlimiting embodiment of figure 4, these means are arranged
inside the body 11. This configuration allows the underwater vehicle to be
used at greater depths than in the document US 20080132130.
These means comprise means making it possible to vary the pitch of
the body 11 comprising, in the nonlimiting example of figure 5, the two
reservoirs 20, 21 spaced apart along the longitudinal axis x and positioned
respectively near the rear end AR and near the front end AV of the body 11.
The means for varying the pitch of the body 11 comprise a hydraulic circuit
36 via which the reservoirs 20, 21 communicate with one another so that a
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fluid can pass from one to the other via a second valve 37 which is able to
close the hydraulic circuit or open it in order to allow or disallow this
fluidic
communication. A second pump 38 allows the liquid to be circulated between
the two reservoirs via the valve 37 and an associated actuator 39 for
actuating the pump 38.
As a variant, the one same pump can be used for varying the pitch
and for varying the buoyancy. A directional-control valve or one or more
additional valves are then provided to connect the pump to one of the two
hydraulic circuits. The directional-control valve or each valve is controlled
by
means of the control member.
The means for regulating the pitch also comprise a control member
allowing control of the means allowing the pitch to be varied as a function of
a setpoint pitch and of a measurement representative of a pitch of the body
11 of the vehicle coming from a measurement device. This control member is
the control member 26 of the buoyancy regulating means in figure 2 but may
be another control member.
The measurement device comprises for example a pitch sensor 28
able to measure the pitch of the underwater vehicle, for example comprising
immersion sensors positioned at the respective two longitudinal ends of the
underwater vehicle or a gravity sensor measuring the verticality of the mast
12 or of the body 11 or an inertial unit.
Regulating the buoyancy and the pitch using the same reservoirs as
depicted in figure 5 means that these means can be shared thereby limiting
the volume dedicated to these regulating operations and the number of
elements dedicated to this regulation.
Advantageously, the means for regulating the pitch are configured in
such a way as to allow the underwater vehicle to be positioned in a
panoramic configuration. Thus, these means comprise for example two
reservoirs spaced apart along the axis x.
Other types of controllable internal means may be used to vary the
pitch of the underwater vehicle, such as masses capable of translational
movement along the axis x, an example of which is described in document
GB 2 335 888. However, that system requires an additional and dedicated
actuator.
In a variant, the reservoirs 20, 21 of the regulating means are replaced
by variable-volume reservoirs as described earlier.
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The use of a pivoting mast 105 to vary the pitch of the body of the
underwater vehicle may also, as a variant, be envisioned like the one
described in document US 20080132130, balancing thus occurring naturally
upon deployment of the second mast.
The vehicle 10 comprises means of rotation R configured to cause the
vehicle to rotate about the axis xm on receipt of a rotation command when
the vehicle is in the panoramic configuration. These means of rotation
comprise the thruster and the panoramic configuration means as well as a
control member configured to control the thruster 14, on receipt of a
command to rotate, so that it generates a torque about the axis the axis xm in
order to cause the body and the axis xm to rotate about the underwater
vehicle, the underwater vehicle being in a panoramic configuration. The
panoramic configuration is preferably, although not necessarily, a panoramic
configuration of stabilization.
In the nonlimiting example of the figures, this control member is the
member 26.
Advantageously, the control member 26 is configured to implement
the rotation step when the axis x is inclined (namely the axis x forms, with
the
axis xm, an angle a different from 00 or 180 ) with respect to the axis xm. If
the axis xm is initially aligned with the axis x (equal to 0 or 180 ), the
control
member 26 is configured to vary the angle a before implementing the rotation
step.
The panoramic position is advantageously a panoramic configuration
of stabilization.
Advantageously, the means of rotation R are configured to position the
underwater vehicle in a predetermined panoramic configuration before
implementing the rotation step so that the vehicle is in this panoramic
position during the rotation step. Thus, the control member 26 is configured
to command the panoramic configuration means in such a way as to bring
the vehicle into this panoramic configuration. In a predetermined panoramic
configuration, the operational configuration of the mast is predetermined and
the height of the end 12a of the mast or of the payload 13 is predetermined.
The invention also relates to a method for controlling a marine vehicle
comprising a rotation step, during which the thruster generates torque about
the axis the axis xm when the vehicle is in the panoramic configuration, so as
to cause the body and the axis xm to rotate about the underwater vehicle.
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Advantageously, the method comprises a panoramic configuration
step to place the vehicle in the predetermined panoramic configuration. This
step potentially comprises a step of deploying the mast 12 from a stowed
configuration into the operational configuration by pivoting the mask with
respect to the body about a pivot connection connecting the mast to the
body, prior to the rotation step, so as to bring the mast into the
predetermined
operational configuration of the panoramic configuration.
The panoramic configuration step may comprise a step of adjusting
the buoyancy so that the panoramic configuration is a panoramic
configuration of stabilization.
The panoramic configuration step may comprise a step of regulating
the pitch of the underwater vehicle.
Each control member may comprise one or more dedicated electronic
circuits or a general purpose circuit. Each electronic circuit may comprise a
reprogrammable calculation engine (a processor or a microcontroller for
example) and/or a computer executing a program comprising a sequence of
instructions and/or a dedicated calculation engine (for example a collection
of
logic gates such as an FPGA, a DSP or an ASIC, or any other hardware
module).
