a deployed position wherein the arm is inclined relative to the longitudinal main axis so as to bring and/or stabilise the vehicle in the so-called vertical position with a trim angle greater than 70° relative to its nominal position (and ideally 90°).

As illustrated in FIGS. 3A, 3B, 4A and 4B, the autonomous underwater vehicle 30 comprises an uprighting device comprising a single arm 32. The arm 32 comprises two ends, one distal end and one proximal end. The proximal end is the end of the arm 32 which is rotatably mounted on the hull 40 of the vehicle 30 and the distal end comprises a float 34, i.e. an element wherein the volume density is less than that of water. The float 34 is rigidly connected to the arm 32.

As seen in FIGS. 3A and 3B, the arm is capable of being disposed in a retracted position wherein the float 34 is here retracted inside the hull 40 of the vehicle 30. In this retracted position, the arm is disposed substantially parallel with the longitudinal main axis 38 of the vehicle 30, so as not to project from the hull 40 of the vehicle 38, and therefore not impact the movement of the vehicle 30 (by creating drag forces).

The arm 32 is rotatably mounted on the hull 40 so as to be at least rotatable and form an angle relative to the longitudinal main axis 38 in the deployed position, as illustrated in FIGS. 4A and 4B.

The axis of rotation is an axis orthogonal to the longitudinal main axis 5, and oriented along the direction 23c of the frame of reference 23 reproduced in FIGS. 4A and 4B. The rotation of the arm 32 from the retracted position to the deployed position makes it possible to place the float 34 at a distance from the hull 40 of the vehicle 30.

By thus disposing the float 34 at a distance of the hull 40 of the vehicle, floatability of the float acts upon the position of the centre of thrust of the vehicle.

Indeed, when the arm 32 is in the deployed position, the float 34 is placed at a distance from the hull 40 of the vehicle 30, such that this influences the position of the centre of the thrust of the vehicle 30. In particular, the float 34 makes it possible to move a volume of water at a distance from the hull 40 of the vehicle 30, such that the position of the hydrostatic forces applied to the vehicle 30 is modified giving rise to the modification of the position of the centre of thrust. The deployment of the arms then makes it possible to act mainly on the position of the centre of thrust, by moving it towards the nose 42 of the vehicle 1.

Thus, during the deployment of the arm 32, the vehicle can continue its movement towards the vertical and the stability of the vehicle in the vertical position can be enhanced. The features of the arms and the floats are chosen so as to make it possible, during the deployment of the arm, to move the centre of thrust towards the nose 42.

The arm 32 is disposed advantageously, at the bottom hull of the vehicle 30.

The arm of this example is described as passive arm, as its positioning relative to the longitudinal main axis 38 is dependent on the features of the float (for example its floatability) but also on the length of the arm.

According to certain aspects, the arm 32 and the float 34 are configured so that, in the deployed position, the arm 32 is substantially perpendicular to the longitudinal main axis 38 of the autonomous underwater vehicle 30. In certain aspects, the arm 32, in the deployed position, forms an angle with the longitudinal main axis 38 of the vehicle 1 included in the range [80; 100].

The deployment of the arm can be triggered via an actuator or by initiating the uprighting movement, as illustrate in FIGS. 4A and 3A (arrow 41).

In an aspect, the deployment of the arm can be performed via an actuation member then enabling the arm to switch from a retracted position to a deployed position only. Thus, the arm, once deployed, cannot be retracted into the retracted position, wherein the float is retracted into the hull. Such a solution is particularly suitable in the context of so-called consumable autonomous underwater vehicles, usable a single time at sea.

In particular, the actuation member comprises a spring arranged between the arm 32 and the hull 40 of the vehicle 30 and a switch (cutout type for example, on/off) configured to activate the spring, so that the latter exerts a force on the arm 32 to switch it from a retracted position, substantially perpendicular to the main axis 38, to a deployed position. Activate means that the switch is configured to enable the spring to apply a force on the arm 32, such that it adopts a deployed position.

Even though a single arm is illustrated, it is possible to have two or more arms, fastened to the hull, preferably to the bottom hull, at port and at starboard. The arms are then preferably arranged so as to form an angle within the range [60°; 180°].

The operation of these so-called passive arms 32 requires an initiation of uprighting (as described above), via the trimming tanks (not shown) and/or by the thrust system 36 of the vehicle.

For uprighting with this passive arm 32, the trimming tanks and/or the thrust system 36 are controlled to initiate uprighting, and the passive arm 32 is then deployed to obtain a synergistic action with the trimming tanks and/or the thrust 36. When the deployment of the arm 32 is performed via an actuation member, the arm 32 is then deployed “at the right time” when the initiation of the uprighting enables the vehicle to have a trim of the order of 70°, making it possible to improve the verticality and the stability of the AUV in the vertical position.

In the case where the vehicle comprises more than one arm 32, the deployment of the arms can be performed simultaneously or one after the other according to a sequence, such as for example starboard then port.

With reference now to FIGS. 5A, 5B, 6A and 6B, the vehicle 50 comprises two arms 52, 62 respectively comprising two floats 54, 64 at their distal end. The arms are attached preferably to the bottom hull, respectively at port and at starboard. Advantageously, the arms are disposed so as to form an angle 66 within the range [60°; 180°].

The arms 52, 62 can be actuated via an actuation member enabling one of the arms to switch from a retracted position to a deployed position and conversely.

In an aspect, the actuation member for deploying the arms 52, 62 and conversely, comprises in particular a motor, capable of orienting the arms 52, 62 in several angular positions relative to the longitudinal main axis. Thus, the motorised arms 52