WO2014067563A1

WO2014067563A1 - Remote controlled mobile platform able to move through a medium such as water and air

Info

Publication number: WO2014067563A1
Application number: PCT/EP2012/071496
Authority: WO
Inventors: André SCHAER
Original assignee: Schaer André
Priority date: 2012-10-30
Filing date: 2012-10-30
Publication date: 2014-05-08

Abstract

The invention is a mobile platform intended to be remotely controlled and comprising two pairs of thrusters (Ρ₁, P₂; P₃, P₄) having respective propulsion axes (Δ₁, Δ₂; Δ₃, Δ₄) orientable in two planes that are parallel to one another and to a longitudinal axis (X₁, Χ'₁) of the platform, each thruster comprising a respective marine propeller (HM₁, HM₂; HM₃, HM₄) and an air propeller (HA₁, HA₂; HA₃, HA₄) and a motor (M₁, M₂ - M₃, M₄) for driving the rotation of the marine and air propellers, the platform also comprising means for switching over the coupling between the motor and one or other of the propellers by reversing the direction of rotation of the motor. Such a platform may form a drone able to move both in the air and in the water.

Description

REMOTE CONTROLLED MOBILE PLATFORM TO EVOLVE IN AN ENVIRONMENT SUCH AS WATER AND AIR.

The present invention relates to a remotely controlled mobile platform adapted to evolve in a medium such as water and air, in particular for performing underwater and aerial reconnaissance.

It relates more particularly to an energy-autonomous platform remotely controllable from a control station located on the ground or on a surface vessel, this platform being equipped with means for receiving the pilot data from said control station. / control and to transmit to it the data from onboard sensors aboard said platform, such as a video camera, a geo-location device, a sonar, a bathymetry device, an acoustic navigation beacon , physicochemical sensors or others.

Moreover, in many applications, particularly when the platform is required to evolve in a nerve, hostile or adverse environment, it is desirable that this platform is as little detectable as possible.

Thus, for example, in the case of the radio remote control of an air platform, the question that arises is that of the deletion of the radiofrequency signature. Similarly, in the case of the acoustic location of an underwater platform, the question that arises is that of the suppression of the acoustic signature. These two requirements are combined in the case of a remote-controlled platform able to evolve in a medium such as water and air, especially for underwater and aerial reconnaissance.

It is clear that in both cases, the platform should be made "silent" while allowing it to evolve, if only to point a target. Of course, this problem appears a priori hardly soluble since the majority of the noise is generated by the propulsion and / or levitation means used which, as a rule, are relatively noisy. It is known, moreover, that one of the great difficulties that arises in the design of such apparatus lies in the resolution of stability problems, especially in the stationary state, for example when acquisition and maintenance of an orientation for visual or other purposes. In this respect, the French patent FR 2 796 217, published on February 2, 2001, proposes a remotely controlled mobile platform able to evolve in a medium such as water or air; said platform is characterized in that it has a density close to that of the medium in which it is located and in that it comprises at least two pairs of steerable thrusters in two planes parallel to each other and to the axis longitudinal of the platform.

In the underwater version, the platform is equipped with hydraulic reactors; as for the aerial version, it comprises a dirigible type structure. It is clear that these two configurations are not compatible in the case of a remote controlled mobile platform able to evolve in a medium such as water and air. The invention therefore more particularly aims to solve these problems.

It proposes, for this purpose, a platform comprising two pairs of thrusters whose propulsion axes are orientable in two planes parallel to each other and to the longitudinal axis of the platform, knowing that said thrusters comprise an electric motor which can driving in rotation is a propeller marine propeller or a tractive air propeller, switching coupling between one or the other being effected by reversing the direction of rotation of said electric motor. Thus, the orientation of the thruster propulsion axes, the variation of the speed of rotation of the propellers, and the mode of marine or air propulsion, according to the choice of the direction of rotation of the electric motor, make it possible to evolve the platform. in the water and in the air, meeting the driving requirements in these two environments.

Advantageously, the platform will be equipped with a device for transmitting information between said autonomous platform and a transmitting / receiving station, as described in French patent FR 2 792 478 published on July 13, 2001.

This mode of information transmission via an optical fiber, operating in "full duplex" meets the bandwidth requirements imposed for the real-time transfer of video images; it also meets the requirements defined above, namely:

- in the case of the radio remote control of an aerial platform, the question which arises is that of the deletion of the radiofrequency signature, - in the case of the acoustic location of an underwater platform, the issue is the removal of the acoustic signature. Thus, in the case where the platform is intended to evolve in the aquatic environment, the four propellers will be able to operate thanks to the action of the marine propellers, in propulsive mode, the blades of aerial propellers will be folded under the effect of the flow aquatic, offering low resistance to underwater propulsion.

Similarly, in the case where the platform is intended to evolve in the air, the four thrusters can operate through the action of aerial propellers, in tractive mode, the blades of aerial propellers will be deployed under the centrifugal effect , marine propellers offering low resistance to air propulsion.

Advantageously, the platform, intended to evolve in an air and aquatic environment, will be energetically autonomous, thanks to batteries whose stored energy density is high.

Of course, the configuration of the thrusters, in terms of orientation and servocontrol of the speed of rotation of the propellers, in the aquatic environment will be different from that in the air. More specifically, in the aquatic environment, the orientation of the four propellers will be variable depending on the desired trajectory of the platform (horizontal navigation, diving or climbing), and the rotational speeds of the propellers marine propellers will vary according to the propulsion speed and course change. In the air environment, the four thrusters will be oriented vertically, the aerial propellers being tractive, and the rotational speeds of these will be variable according to the desired trajectory of the platform (ascent, descent, forward, reverse and Change of direction) ; this mode of operation is similar to that of a swashplate of a rotary wing.

Therefore, this mode of propulsion, whether in the aquatic environment or in the air, will allow starboard / port turning maneuvers, ascent / descent without any rudder.

Of course, the mechanical design of the platform will be such that its density is very slightly less than the density of the aquatic environment, and compatible with the thrust of the thrusters in an air environment.

In both cases, an inertial unit will restore the horizontal attitude of the platform, in the absence of maneuvers made from the control / command station. One embodiment of the invention will be described below, by way of non-limiting example, with reference to the accompanying drawings in which:

FIGS. 1 and 2 are diagrammatic representations of a mobile platform according to the invention in a marine configuration seen from above (FIG. 1) and seen in profile (FIG. 2),

FIGS. 3 and 4 are diagrammatic representations of the mobile platform of FIGS. 1 and 2 in aerial configuration seen from above (FIG. 3) and in profile view (FIG. 4),

FIG. 5 is a cross-section of a thruster for the platform of FIGS. 1 to 4, in marine configuration, and - Figure 6 is a cross section of the thruster of Figure 5 in air configuration.

In the examples represented in FIGS. 1 to 4, the mobile platform consists of a tubular central beam T and four orientable thrusters Pi to P ₄ situated on either side of the beam T, namely:

two thrusters Pi, P ₃ orientable around a common axis X ₂ , X ' ₂ perpendicular to the longitudinal axis XX, and

two thrusters P ₂ , P ₄ orientable about a common axis X ₃ , X ' ₃ , parallel to the axis X ₂ , X' ₂ , and perpendicular to the longitudinal axis Xi, X'i.

The central beam T may contain, at each of its ends, a video camera shooting associated with a lighting headlight, or possibly a night vision camera with image intensifier or an infrared camera; these different cameras will be mounted in a hemispherical transparent bulb B¾, BH ₂ , extending the ends, respectively front and rear, of the central beam T; in the illustrated example, it also comprises an inertial unit for controlling the orientation of the thrusters and the speed of rotation of the propellers concerned so as to maintain the horizontal attitude of the platform in the absence of maneuvers made to from an unrepresented control / command station.

This central beam T may also include sensors intended to transmit information to the control / command station relating to the medium concerned, marine or air; these sensors are advantageously adapted to the medium concerned so as to facilitate the control of the platform.

By way of example, and in a non-exhaustive manner, the sensors intended for the marine environment may be as follows:

an ultrasound probe,

- a hydrophone, - a bathymetry probe,

- an underwater navigation beacon,

physico-chemical sensors (turbidity, salinity, pH, etc.). Similarly, sensors intended for the air environment; may be:

- altimeter,

- GPS.

And in a general way, intended for both types of environment:

- external temperature sensor,

- artificial horizon,

- battery voltage meter,

- laser pointer. The central beam T is also equipped with an information transmission device between the platform and the control / command station, as described in French patent FR 2 792 478 published on July 13, 2001.

This device, not shown, comprises a coil of optical fiber that can rotate freely about an axis perpendicular to the longitudinal axis Xi, ΧΊ, thus allowing the optical fiber to unfold as and when the progress of the platform; this device is advantageously located under the central beam T, preferably in the central position; in addition, said coil comprises a device for converting optical information into electrical information and vice versa; the electrical information is then transmitted to an electronic module, not shown, located in the central beam, by means of rotating electrical joints, said electronic module ensuring on the one hand the transmission of the control information to the four thrusters Pi, P ₂ , P ₃ , P ₄ , and on the other hand the transmission of information from the various sensors and in particular the video images. Advantageously, the aforesaid coil may comprise a sheath of small diameter (about 900 μηι) comprising three optical fibers, each of which will have a diameter of 250 μιη, thus enabling the simultaneous transmission of video images from the front and rear cameras, the artificial horizon, pilot data and data from RS 422 or RS 485 sensors.

In the example illustrated by FIGS. 1 to 4, the four thrusters P 1, P ₃ - P ₂ , P ₄ each comprise a tabular structure TU ₁ , TU ₃ - TU ₂ , TU _{4 respectively} , whose principal axes Δι , Δ ₃ - Δ ₂ , Δ ₄ , respectively pivot about the axes X ₂ , X ' ₂ and X ₃ , X' ₃ , essentially +/- 90 ° on either side of an initial position situated in the plane containing the three aforesaid axes X ₁₅ X ' ₁ , X ₂ , X' ₂ and X ₃ , X ' ₃ . The axes of the tubular structures fulfill the conditions: Δι, Δ ₃ perpendicular to X ₂ , X ' ₂ and Δ ₂ , Δ ₄ perpendicular to X ₃ , X' ₃ .

These tubular structures TUi, TU ₃ - TU ₂ , TU ₄ are integral with supports, respectively SU], SU ₃ - SU ₂ , SU, the main axes of which are collinear respectively with the axes X ₂ , X ' ₂ and X _3. , X ' ₃ .

These four sets, TUySUi, TU ₂ / SU ₂ - TU ₃ / SU ₃ , TU4 / SU4, constitute the four thrusters Pi, P ₃ - P ₂ , P ₄ ; each of them is connected to the central beam T via a respective sealed rotary joint located in the respective base, among the four bases EMi, EM ₃ - EM ₂ , EM ₄ , each base being secured to the central beam T. Considering that the front of the platform consists of the bulb BHl, that is to say that the forward movement of the mobile platform is to the right, the four thrusters Pj, P ₂ , P ₃ , P ₄ are named as follows:

- Pi: port forward thruster P _{) 5}

P ₂ : rear port thruster P ₂ ,

P ₃ : starboard propeller before P ₃ , and

- P ₄ : rear starboard thruster P ₄ . In the configuration illustrated in FIGS. 1 and 2, the four thrusters P _ls P ₃ - P ₂ , P ₄ are in "marine" configuration, the marine propellers, respectively HMj, HM ₃ - HM ₂ , HM, located at the rear of each thruster, are propellant type.

As for the aerial propellers, respectively HA _1} HA ₃ - HA ₂ , HA ₄ , located at the front of each thruster, they are represented folded backwards under the effect of a stream of water. The directions of rotation of the four marine propellers HMi, HM ₃ - HM ₂ , HM ₄ will be such that the rotation of the two helices adjacent to the same helix will be of opposite direction; more specifically, the rotation of the forward port and starboard port propellers will be, for example, clockwise; the rotation of the starboard and starboard propellers will therefore be counter-clockwise.

Thus, the two port and starboard aft propellers will be propulsive with a right step; the two starboard propellers forward and port side propeller will be propulsive with a step to the left.

This configuration of the rotational directions of the propellers thus makes it possible to avoid a rolling effect during the displacement of the platform.

In the configuration illustrated in FIGS. 3 and 4, the four propellers P ₁₅ P ₃ - P ₂ , P ₄ are in the "overhead" configuration, the marine propellers, respectively HMi, HM ₃ - HM, HM ₄ , located at the rear thrusters, are immobile.

As for the aerial propellers HAi, HA ₃ - HA ₂ , HA ₄ , located at the front, they are unfolded under the centrifugal effect.

As above, the directions of rotation of the four aerial propellers HA ₁₅ HA ₃ - HA ₂ , HA ₄ are such that the rotation of the two helices adjacent to the same helix are of opposite direction; in a more precise way, the rotation port and starboard port forward propellers are, for example, clockwise; the rotation of the starboard bow and starboard propellers are therefore counter-clockwise.

Thus, the two propellers port forward and starboard rear are tractive with a step to the left; the two starboard propellers forward and port side are tractive with a step to the right.

This configuration of the rotational directions of the propellers thus makes it possible to ensure an almost horizontal plane of lift of the platform. It can easily be assumed that in the "marine" configuration, the four thrusters P _1} P ₃ - P ₂ , P ₄ respectively pivot about the axes X ₂ , X ' ₂ and X ₃ , X' 3, of +/- 90 ° around an initial position situated in the plane containing the three aforesaid axes X _ls X '_1; X ₂ , X ' ₂ and X ₃ , X'3. In the "overhead" configuration, the four thrusters P _ls P ₃ - P ₂ , P ₄ respectively have the axes Δι, Δ ₃ - Δ ₂ , Δ perpendicular to the plane containing the three aforementioned axes Xi, ΧΊ, X ₂ , X ' ₂ and X ₃ , X ' ₃ .

One of the thrusters P1-P4, under the generic reference P, will now be described in greater detail with reference to FIGS. 5 and 6.

The thruster P comprises a tabular enclosure TU whose main axis Δ is the so-called propulsion axis; orthogonally to the axis of propulsion Δ, the axis X, X ', said axis of rotation of the thruster P, is the main axis of a support SU; the tubular enclosure TU and its support SU pivot in the vicinity of a rotary joint JT by means of a hollow shaft A3, integral with the free end of the support SU, which hollow shaft A3 is rotatably mounted relative to a base EM thanks to two bearings R5, R6; the base EM is integral with the central beam T, not shown. The hollow shaft A3 comprises, in the vicinity of its free end, a pinion PII, which meshes with a pinion PI2 driving a servomotor SM integral with the base EM. The tightness of the assembly TU, SU, and EM is provided by a seal J6 in contact with the central beam T, and by a joint J5 of the rotary joint JT; Moreover, the hollow shaft A3 allows the passage of the electrical conductors connecting the various components contained in the thruster towards the control and control members located in the central beam T.

The SU support includes a booster power battery and a VA variator; Furthermore, it comprises a sealed connector, not shown, for recharging the battery. The tabular enclosure TU comprises a motor MO with double shaft outputs; it is electrically powered by said battery BA through said variator VA, which makes it possible to vary the direction of rotation and the rotational speed of said motor MO. The motor MO comprises, in the vicinity of each of its shaft ends, the female part EMU, EM21, of two conical clutches, respectively EM1, EM2; these two female parts EMU, EM21 are slidably mounted on the respective shaft outputs of the motor MO via a helical ramp, not shown, allowing, in the direction of rotation of the motor, to be driven in rotation and to slide axially in two opposite directions.

Vis-à-vis each of the female parts EM11, EM21, two male parts, respectively, EM12, EM22, integral respectively propeller shafts, respectively Al, A2, are rotatably mounted by means of bearings, respectively RI , R2, and R3, R4, in the tabular enclosure TU. A marine propulsion propeller HM is integral with the free end of the shaft A1; likewise, an aerial tractive propeller HA is integral with the free end of the shaft A2; the tightness of the shaft Al is provided by two rotating joints Jl, J2; likewise, the tightness of the shaft A2 is ensured by two rotating joints J3, J4.

Thus, depending on the direction of rotation of the motor MO, it will cause either the marine propulsion propeller HM or the air tractive propeller HA. In order to improve the efficiency of the marine propulsion propeller HM, a cylindrical casing CA, integral with the tabular enclosure TU, channels the flow of water.

The aerial tractive propeller HA comprises a hub HAc integral with the free end of the shaft A2; this hub comprises two pivot axes of two propeller blades HAa, HAb; thus, these two blades can rotate about an axis, respectively Aa, Ab; their stroke respectively is limited firstly by contact with the tubular enclosure TU, and secondly by a stop located in the propeller hub HAc, not shown.

Thus, in the absence of rotation of the shaft A2, in particular under the effect of a flow of water, the blades of propellers HAa, HAb, will be folded, in contact with the tabular enclosure TU; in case of rotation of the A2 tree, these will be deployed and become tractive. In FIG. 5, the thruster P is in the so-called "marine" configuration; in Figure 6, the thruster P is in the so-called "air" configuration.

The mechanical design of the platform according to the invention is such that its density is between 1 and 0.8 times, and preferably between 0.998 and 0.996 times, the density of the aquatic environment. Likewise, the mechanical design of the platform, according to the invention, is such that its mass is between 1 and 0.5 times, and preferably between 0.8 times and 0.5 times, the thrust of thrusters P _t to P ₄ in the air. The piloting of the mobile platform, according to the invention, will be such that a strong analogy between the two modes known as "marine" and "aerial" will make it possible to exploit the same controls from two "right-hand" pedals and "Left hand", each having two degrees of freedom along the horizontal axes longitudinal OX and transverse OY.

The rudder "right hand" will be devoted to throttle control and change of course; the "left hand" rudder will devolve to the modification of the platform attitude. The choice of mode, "marine" or "air", will be made from a simple two-position switch; Of course, the choice of mode, "marine" or "air", will affect several factors that affect the operation of each of the four propellers. Thus, taking into account the actions performed by means of the two "right-hand" and "left-hand" pedals and the "sea" or "air-mode" selection switch, the control of the mobile platform, according to the The invention is similar to that of a rotary wing, knowing that it can evolve in a medium such as water and air indifferently along three orthonormal axes longitudinal Ox, transverse Oy and vertical Oz.

More precisely, the switch "marine configuration / aerial configuration", or more simply said the "water / air" switch intervenes at three levels:

- on the main orientation of the thrusters,

- on the direction of rotation of the four electric motors, - on the "left hand" rudder controls.

Concerning the main orientation of the thrusters:

in the "marine" configuration, the four thrusters Pi, P ₃ -P ₂ , P _4> respectively pivot about the axes X ₂ , X ' ₂ and X ₃ , X' ₃ , of +/- 90 ° around a initial position located in the plane containing the three aforementioned axes X _1; X ' _1? X ₂ , X ' ₂ and X ₃ , X' ₃ ,

in the "overhead" configuration, the four thrusters Pi, P ₃ - P ₂ , P _; respectively have the axes A _h Δ ₃ - Δ ₂ , Δ ₄ , perpendicular to the plane containing the three aforesaid axes X _l5 ΧΊ, X ₂ , X ' ₂ and X ₃ , X' ₃ .

Regarding the direction of rotation of the four electric motors, it will be in one direction in "marine" configuration and in opposite direction in "overhead" configuration, so that depending on the direction of rotation of the engine, the latter respectively drives the propeller marine propulsion HM, the aerial tractive propeller HA.

Moreover, the direction of rotation of the four motors is such that:

- in "marine" configuration:

· The marine propeller propellers on the port bow and starboard side turn clockwise, and

• the marine propeller propellers on the port and starboard bow sides rotate counterclockwise;

- in "air" configuration:

· The aerial propellers on the port bow and starboard sides rotate clockwise, and

• the aerial propellers on the port and starboard bow sides turn counterclockwise.

It should be noted that the direction of rotation of the engine is effectively reversed according to the configuration "marine" or "aerial", knowing that the directions of rotation marine or aerial propellers are seen respectively on the aniele side or on the front side of the engine.

Concerning the controls of the "left hand" rudder, they will be such that:

- in "marine" configuration:

along axes OX and OY, they will act on the orientation of each of the four thrusters,

- in "air" configuration:

along the OX and OY axes, they will affect the rotational speeds of each of the four engines.

The rudder "right hand" is devolved to the control of the gases and the change of course in the following way:

- according to the OY axis:

this command makes it possible to vary the rotation speed Ω of the four motors from Ω = 0 to Ω = Q _max , according to the directions described above; the corresponding names, depending on the configurations, are as follows:

· In "marine" configuration: thrust,

• in "air" configuration fixed wing: gas (throttle),

• in "air" configuration rotary wing: not general (nick).

Of course, the rotational speeds of the four engines will be equivalent at all times.

- according to the OX axis:

this command makes it possible to vary the orientation of the platform to the right or to the left, the attitude being horizontal; the corresponding names, depending on the configurations, are as follows:

• in "marine" configuration: heading, • in "fixed-wing" configuration fixed wing: rudder,

• in "aerial" configuration rotary wing: twist.

In a more precise way:

• in "marine" configuration:

heading to starboard:

port and port port engines: Ω> 0

starboard engines front and rear starboard: Ω = 0

cap to port:

forward port and port port engines: Ω = 0,

starboard engines front and rear starboard: Ω> 0.

• in "air" configuration:

lace to starboard:

Ω (port and starboard engines)> Ω (port and starboard forward engines),

lace on the port side:

Ω (front port and starboard engines) <Ω (front port and starboard engines).

The "left-handed" rudder is dedicated to modifying the attitude of the platform as follows:

- according to the OY axis:

this command makes it possible to vary the incidence of the platform in a vertical plane containing the main axis of said platform; the corresponding names, depending on the configurations, are as follows:

• in "marine" configuration: depth,

• in "air" configuration fixed wing: shutter (elevator),

• in "aerial" configuration rotary wing: pitch (pitch). In a more precise way:

• in "marine" configuration:

diving:

bow thruster forward, port side, starboard bow and aft starboard: a <0,

ascent:

bow thruster forward, port-side, starboard bow and aft starboard: a> 0. in "overhead" configuration:

down :

Ω (front port and starboard engines) <Ω (rear port and starboard rear engines),

to the top :

Ω (front port and starboard engines)> Ω (rear port and starboard rear engines). according to the OX axis:

this command makes it possible to vary the incidence of the platform in a vertical plane perpendicular to the main axis of said platform; the corresponding names, depending on the configurations, are as follows:

• in "marine" configuration: gîte,

• in "fixed wing" configuration: wing (ailvator),

• in "aerial" configuration rotary wing: roll.

In a more precise way:

• in "marine" configuration:

starboard cottage:

orientation of forward port thrusters, aft port: a>0; orientation of the starboard bow thrusters: a <0, lodging on the port side:

bow thruster forward, port port forward: a <0; orientation of the starboard bow thrusters: a> 0.

• in "air" configuration:

starboard cottage:

Ω (port-side and port-side engines)> Ω (starboard engines for starboard and starboard),

lodging on the port side:

Ω (front port and port port engines) <Ω (starboard engines on the starboard and starboard sides).

Thus, thanks to the actions carried out by means of the two "right-hand" and "left-handed" spreaders, the steering of the mobile platform, according to the invention, is similar to that of a rotary wing, knowing that it can evolve indifferently according to the three orthonormal axes Ox, Oy and Oz; only the water / air mode switch determines the choice of medium such as water or air.

Two transitions of water / air media can be envisaged as follows:

- To perform the air / water transition, the platform evolves in an air environment, approaches the vertical surface of the water until it floats naturally and, thanks to the air / water commutation, the direction engine rotation reverses, driving the marine propellers, the thrusters are oriented dive incidence, the aerial propeller folds under the effect of the flow of water; the platform evolves in the marine environment.

- To perform the water / air transition, the platform evolving in the marine environment approaches the vertical surface of the water until it floats naturally and, thanks to the water / air switching, the propellants are oriented in a vertical position, the direction of rotation of the engines are reversed, causing the aerial propellers unfolding under the centrifugal effect, the marine propellers being immobile; the platform rises from the surface of the water and evolves in an air environment.

Thus, it can be seen that according to the air / water or water / air transition, the sequences of reversal of the direction of rotation of the motors and orientation of the thrusters are different. During the air-to-water transition, from a stationary state, only the throttle control (right-hand rudder, according to OY) will be required to approach the water surface vertically up to natural floatation. As for the water / air transition, the throttle control ("right hand" rudder, according to OY) and the control of the propeller thrust ("left hand" rudder, according to OY) will be necessary to make a vertical approach from the surface of the water to natural flotation. Of course, the platform, according to the invention, is adapted to pose, as a rotary wing, on the ground or on the deck of a building surface.

Claims

claims

1. Mobile platform for remote control,

characterized in that it comprises two pairs of thrusters (Pi, P _2, P ₃ , P ₄ ) having respective propulsion axes (Δ _{ΐ 5} Δ ₂ , Δ ₃ , Δ ₄ ) orientable in two planes parallel to each other and to a longitudinal axis (X ₁₉ ΧΊ) of the platform, each thruster comprising a propellant marine propeller (HM ₁₅ HM¾ HM ₃ , HM) and a tractive air propeller (HA HA _2, HA ₃ , HA ₄ ) respectively, each propellant further comprising an electric motor (Μ _ΐ5 M ₂ - M ₃ , M ₄ ) for driving in rotation either the marine helix or the overhead propeller, the platform further comprising means for switching a coupling between said engine and the one or the other of the marine and air propellers, said switching means comprising means for reversing the direction of rotation of said electric motor.

2. Platform according to claim 1,

characterized in that each thruster (P _r P ₄ ) of a pair has a common axis of rotation (X ₂ , X '₂; X ₃ , X' ₃ ) with a thruster of the other pair.

Platform according to claim 1,

characterized in that it is adapted to evolve in an aquatic environment, and in that the aforesaid propellants (P ₁₅ P _2; P ₃ , P) comprise means for generating a flow of water for propelling the aforesaid platform.

Platform according to claim 1,

characterized in that it is adapted to evolve in an air environment, and in that the aforesaid propellants (Pi, P ₂ - P ₃ , P ₄ ) comprise means for generating a flow of air serving to ensure the lift of the said platform.

Platform according to claim 3,

characterized in that its density is between 1 and 0.8 times, and preferably between 0.998 and 0.996 times, the density of the aquatic medium.

Platform according to claim 4,

characterized in that its mass is between 1 and 0.5 times, and preferably between 0.8 and 0.5 times, the thrust of the thrusters (P _ls P ₂ - P ₃ , P ₄ ) in an air medium .