MEASURING DEVICE INTENDED TO BE IMMERSE

The field of the invention is that of measuring devices intended to be immersed. The measuring device comprises a reference axis and is able, when it is submerged, to be in a deployed configuration in which the arms are distributed around the reference axis and carry a set of measuring blocks each comprising at least an acoustic sensor, and in which the reference axis extends substantially vertically. The measuring blocks generate a torque of the measuring device around the reference axis during a vertical translation of the measuring device in the deployed configuration.

The invention relates in particular to air-dropping acoustic buoys (“sonobuoy” in English terminology) of the type described in patent application WO2010025494. The air-dropping buoy measuring device is an acoustic signal reception antenna comprising an acoustic sensor network. The measuring device is suitable for being in a stowed configuration in which it is housed in a tubular housing until the buoy is submerged. The arms then extend parallel to the axis r. The arms are released and deployed when the buoy is submerged.

However, due to their inclination, the acoustic sensors generate a torque of the measuring device 500, around the axis r of the dive line, substantially vertical, during a translation of the measuring device 500 along an axis vertical. The direction of the rotation caused by a vertical translation of the measuring device 500 upwards is represented by an arrow in FIG. 1.

This rotation of the measuring device has the effect of degrading its performance. On the one hand, the flow of water over the acoustic sensors disturbs their hydroacoustic performance. On the other hand, the rotational movement of the acoustic sensors makes it difficult to know precisely their positions around the axis of the dive line, which has an unfavorable impact on the accuracy of the measurements of the receiving antenna, in particular on the precision of the position of targets detected in a terrestrial reference frame.

One solution for improving positioning accuracy consists in equipping the buoy with a compass capable of ensuring sufficiently precise positioning even in the presence of the rotation generated by the arrangement of the sensors. However, this increases the cost of the compass at least tenfold. Furthermore, this solution does not improve the hydroacoustic performance of the hydrophones which remain subject to the flow of water, which limits the performance of the buoy.

An alternative solution consists in equipping the buoy with a tarpaulin which deploys between the sensors when the arms are deployed. This tarpaulin, which increases the vertical drag of the measuring device, has the function of limiting the vertical movements of the sensors. The drag of the tarpaulin strongly limits vertical movements. However, a change in depth of the hydrophones at a sufficient speed may be desirable in particular for carrying out measurements at different depths. Moreover, this solution is only really effective with light antennas and it is bulky and expensive.

The uncontrolled vertical movements of the measuring device are mainly due to the swell, that is to say to a vertical movement of a body with positive buoyancy (referred to as a floating body in the following) placed above the measuring device and connected to this device by the diving line. The movements of the floating body due to the swell are transmitted to the measuring device via the dive line. One solution consists in limiting the vertical movements of the measuring device by making part of the dive line between the floating body and the measuring device in the form of a damping spring ensuring decoupling between the vertical movements of the floating body and of the device. of measurement. The movements due to the swell have an amplitude of the order of 5 meters on either side of a position of equilibrium. Gold, when the weight of the submerged part of the buoy is important, it may prove to be complex, if not impossible, to find a spring capable of exhibiting variations in elongation of 5 m on either side of a position of balance to ensure decoupling, while presenting a drag greater than the weight of the submerged part of the buoy. In other words, for this solution to be effective, the forces associated with the movement of the swell must be greater than the forces present in the static shock absorber spring. Therefore, for this solution to work, the buoy must be light and have significant drag. Moreover, the choice of this solution leads to replacing a great length of cable of the diving line by a damping spring, which is expensive and bulky. to find a spring capable of exhibiting variations in elongation of 5 m on either side of a position of equilibrium to ensure decoupling, while having a drag greater than the weight of the submerged part of the buoy. In other words, for this solution to be effective, the forces associated with the movement of the swell must be greater than the forces present in the static shock absorber spring. Therefore, for this solution to work, the buoy must be light and have significant drag. Moreover, the choice of this solution leads to replacing a great length of cable of the diving line by a damping spring, which is expensive and bulky. to find a spring capable of exhibiting variations in elongation of 5 m on either side of a position of equilibrium to ensure decoupling, while having a drag greater than the weight of the submerged part of the buoy. In other words, for this solution to be effective, the forces associated with the movement of the swell must be greater than the forces present in the static shock absorber spring. Therefore, for this solution to work, the buoy must be light and have significant drag. Moreover, the choice of this solution leads to replacing a great length of cable of the diving line by a damping spring, which is expensive and bulky. while having a drag greater than the weight of the submerged part of the buoy. In other words, for this solution to be effective, the forces associated with the movement of the swell must be greater than the forces present in the static shock absorber spring. Therefore, for this solution to work, the buoy must be light and have significant drag. Moreover, the choice of this solution leads to replacing a great length of cable of the diving line by a damping spring, which is expensive and bulky. while having a drag greater than the weight of the submerged part of the buoy. In other words, for this solution to be effective, the forces associated with the movement of the swell must be greater than the forces present in the static shock absorber spring. Therefore, for this solution to work, the buoy must be light and have significant drag. Moreover, the choice of this solution leads to replacing a great length of cable of the diving line by a damping spring, which is expensive and bulky. for this solution to work, the buoy must be light and have significant drag. Moreover, the choice of this solution leads to replacing a great length of cable of the diving line by a damping spring, which is expensive and bulky. for this solution to work, the buoy must be light and have significant drag. Moreover, the choice of this solution leads to replacing a great length of cable of the diving line by a damping spring, which is expensive and bulky.

An aim of the present invention is to limit at least one of the aforementioned drawbacks.

To this end, the invention relates to a measuring device intended to be immersed in water comprising a set of arms and a reference axis, the measuring device being suitable for being in a deployed configuration, the measuring device comprising a set of measuring blocks carried by arms of the set of arms and each comprising an acoustic wave sensor, the set of measuring blocks being configured and arranged so as to generate a torque of the measuring device around the reference axis during a vertical translation of the measuring device in the deployed configuration, the measuring device comprising compensation means configured and arranged so as to generate another torque of rotation of the measuring device around the 'reference axis during vertical translation,the other torque being directed in the opposite direction to the torque and having an intensity less than twice that of the torque.

Advantageously, the arms extend radially around the reference axis.

Advantageously, each measuring block of the measuring assembly comprises a first contact surface with water intended to be in direct physical contact with water and oriented, in the deployed configuration, so that it undergoes, under the 'effect of the flow of water on the first water contact surface during vertical translation, a first force comprising a vertical component and a horizontal component comprising a tangential component generating an individual torque of the device for measurement around the reference axis, the individual torques generated by the measuring blocks of the measuring assembly being oriented in the direction of the torque,

Advantageously, the compensation means comprise a set of at least one compensation block comprising a second water contact surface intended to be in direct physical contact with the water and oriented, in the deployed configuration, so that it undergoes, under the effect of the flow of water on the second surface in contact with the water during vertical translation, a second force comprising a vertical component and a horizontal component comprising a tangential component generating a torque of individual compensation rotation of the measuring device around the reference axis, the individual compensation rotation torque being oriented in the opposite direction to the rotational torque.

Advantageously, the device according to the invention comprises at least one of the characteristics below taken alone or in combination:

- the other torque has an intensity substantially equal to the intensity of the torque,

- the compensation means comprise a set of at least one compensation block intended to be in direct physical contact with the water and undergoing, under the effect of the flow of water on its surface during vertical translation , a force having a tangential component to the reference axis so as to generate another individual torque of the measuring device around the reference axis in the opposite direction to the torque,

- the compensation block is arranged and configured so that the force undergone by the compensation block has a horizontal component comprising only a tangential component,

- the set of at least one compensation block extends between two adjacent arms,

- at least one compensation block is carried by an arm,

- each compensation block is configured and arranged so as to generate, during vertical translation, an individual torque of the measuring device around the reference axis in the opposite direction to the torque,

- the set of at least one compensation block and the set of measuring blocks is fixed to the set of arms,

a compensation block is associated with each measurement block, the compensation block associated with a measurement block being fixed to the same arm as the measurement block and being configured and arranged so as to generate, during vertical translation, an individual torque of the measuring device substantially in the opposite direction of an individual torque generated by the measuring unit during this same vertical translation,

- the individual torque generated by the compensation unit is substantially opposed to the individual torque generated by the measurement unit,

- the arms are telescopic and each include several segments able to slide relative to each other, the compensation block being fixed on the same segment as the associated measuring block,

- the measuring unit is monobloc with the associated compensation unit,

- the compensation unit occupies, around the reference axis r, an angular sector of opening which is smaller than an angular sector occupied by the measuring device with which it is associated,

- the set of measuring blocks comprises a subset of measuring blocks mounted on the same arm, the measuring blocks of the subassembly being arranged on the same side of the radial plane with the reference axis passing through l axis of the arm,

- Each compensation block mounted on the arm is placed on the other side of the radial plane.

- the second contact surface with water having an inclined mean normal, in the deployed configuration, with respect to the reference axis and with respect to a tangential axis, defined with respect to the axis of

reference, so as to generate the individual compensating torque of the measuring device around the reference axis,

- the second contact surface with water is oriented in the direction of vertical translation,

- the compensation block has the shape of an essentially parallelepipedal plate,

- a straight line passing through a leading edge and a trailing edge of the compensation block has an inclined normal, in the deployed configuration, with respect to the reference axis and with respect to a second tangential axis, defined by relative to the reference axis, so as to generate the individual torque of the measuring device around the reference axis,

the first contact surface with water has an average normal inclined with respect to the reference axis and with respect to a tangential axis, defined with respect to the reference axis, so as to generate the individual torque of the measuring device around the reference axis

- at least one compensation block incorporates a measuring element other than an acoustic sensor,

- at least one compensation unit has no measuring element other than an acoustic sensor,

- the measuring device is suitable for being in a row configuration in which the arms are inscribed in a cylinder whose axis is the reference axis, the measuring blocks and the compensation means being configured and arranged so as to be housed in said cylinder when the measuring device is in the stored configuration,

- The arms extend in a plane substantially perpendicular to the reference axis in the deployed configuration.

The invention also relates to a buoy comprising a measuring device according to the invention.

Advantageously, the acoustic buoy comprises a floating body and a diving line to which the floating body and the arm are connected, the buoy being configured so that the floating body floats on the surface of the water and the diving line s' extends longitudinally along a vertical axis substantially coincident with the reference axis when the measuring device is in the deployed configuration.

The invention will be better understood by studying a few embodiments described by way of non-limiting examples, and illustrated by the appended drawings in which:

- Figure 1 already described schematically shows in perspective a deployed receiving antenna of the prior art,

- Figure 2 already described schematically shows a cross section of a buoy of the prior art stored in a cylindrical housing before immersion,

- Figure 3a schematically shows the release of an air-dropping buoy from an aircraft, Figure 3b shows the immersion of the air-dropping buoy and Figure 3c schematically shows the start of the deployment of the buoy after its immersion,

- Figure 4 shows schematically the internal elements of a deployable buoy in row configuration,

- Figure 5 shows schematically the buoy of Figure 4 when the arms are extended,

- Figure 6 shows schematically the buoy of Figure 4 in a deployed configuration,

- Figure 7 shows more precisely an example of an air-dropping buoy deployed according to the invention,

- Figure 8 shows more precisely the deployed arms carrying sensor blocks,

- Figure 9 schematically shows a section of one of the arms along a vertical plane tangential to the reference axis r and passing through one of the sensor blocks,

- Figure 10 shows schematically the arms in a folded configuration,

- Figure 11 shows schematically a cross section of the arms initially in folded configuration and housed in the housing, the body 9 not being shown for clarity.

From one figure to another, the same elements are designated by the same reference numerals.

The invention applies to measuring devices intended to be immersed and comprising measuring blocks comprising acoustic sensors and being carried by arms distributed angularly around a reference axis of the measuring device. The measuring device is suitable for being in a deployed configuration in which a reference axis of the measuring device is substantially vertical and in which the measuring blocks generate a torque of rotation of the measuring device around the reference axis during 'a vertical translation of the measuring device in the deployed configuration.

The deployed configuration is substantially stable in the sense that the orientation of the arms relative to the reference axis is substantially stable.

The reference axis can be the longitudinal axis along which extends a physical dive line, connected to the arms, when the measuring device is in the deployed configuration and / or to a support body on which the arms are mounted.

Each measuring unit comprises at least one acoustic wave sensor capable of (or configured to) measuring acoustic waves, for example, a hydrophone or an electroacoustic transducer.

Each measurement block can comprise at least one other means of a measurement chain of an acoustic wave such as for example an amplifier to amplify the measurement obtained by the acoustic sensor and / or an analog-to-digital converter to convert a measured signal and possibly amplified and / or at least one acoustic wave transmitter. An acoustic wave transmitter is a means of a measurement chain intended to measure an acoustic wave comprising an acoustic wave sensor intended to measure an acoustic wave reflected on a target from an acoustic pulse emitted by the transmitter acoustic waves.

The different measurement blocks can include different elements.

The measuring device may, for example, comprise an antenna for receiving acoustic waves from a sonar and possibly a transmitting antenna.

The invention applies in particular to air-dropable acoustic buoys comprising a measuring device comprising an acoustic reception antenna.

The following description will be given with reference to air-dropping acoustic buoys in the remainder of the text, but it applies to any other measuring device as described above and to any other underwater device suitable for being submerged comprising such a measuring device. acoustic waves.

The invention applies, for example, to any deployable measuring device in which the arms are connected to a support body comprising a reference axis r fixed relative to the support body. The arms are distributed around the axis r and each of the arms is able to be in a folded configuration, when the measuring device is in a storage configuration, and in a deployed configuration, when the measuring device is in a storage configuration. deployed. One of the ends of each arm moves away from the axis r during the passage from the folded configuration to the deployed configuration. Advantageously, the arms are distributed angularly, preferably but not necessarily in a regular manner, around the axis r.

As a variant, the measuring device is permanently in the deployed configuration.

The arms can have a fixed length or be extensible, for example telescopic. The arms then have a stored configuration in which they are in a folded configuration and have a minimum length, the measuring device is then in the stored configuration. They go from the stowed configuration to the deployed configuration by lengthening the arms and by changing from the collapsed configuration to the deployed configuration.

The arms can have a fixed length or be extensible, for example telescopic. The arms then have a stored configuration in which they are in a folded configuration. They go from the stowed configuration to the deployed configuration by lengthening the arms and by changing from the collapsed configuration to the deployed configuration.

Le dispositif sous-marin peut comprendre une ligne de plongée reliée au corps de support, la ligne de plongée s’étendant sensiblement selon l’axe de référence et sensiblement verticalement au début du déploiement des bras.

The underwater device comprises, when the measuring device is deployable, deployment means making it possible to move the arms to their deployed configuration. These deployment means can comprise deployment lines of the stay cable type. Each stay is connected, on the one hand, to one of the arms and, on the other hand, to a diving line connecting the support body to a float so that under the effect of the immersion of the device, the float and the support body move away from each other causing a deployment of the diving line which comes to stretch, extend vertically along the reference axis and tighten the shrouds which pull on the arms.

As a variant, floats are for example fixed to the distal ends of the arms, so that when the arms are released, the floats ensure the deployment of the arms. Alternatively, torsion springs can be installed at the joints of the arms to the support body. The winding axis of each torsion spring extends along the axis of the pivot link connecting the arm to the support body.

The underwater device can be configured so that the arms automatically switch from the stowed configuration to the deployed configuration when submerging the underwater device or can be configured to deploy the arms on command.

FIG. 3a represents an aircraft A dropping an acoustic buoy 1 according to the invention in a marine environment with the aim of detecting acoustic waves corresponding to acoustic waves emitted or reflected (echoes) by potential targets 3. The buoy 1 could in variant be released from a surface vessel, for example from a platform or an underwater vehicle. In Figure 3a, the buoy 1 and the measuring device is in an initial storage configuration in which the elements of the buoy are housed in a housing 4. When the acoustic buoy 1 is released, a parachute 5 of the buoy is

automatically deployed to slow down its fall as shown in Figure 3b. Once the buoy is submerged, the internal elements of the buoy come out of the housing 4 as shown in Figure 3c. The buoy comprises a floating body 7 initially housed in the housing 4 in the stowed configuration of the buoy and configured to rise to the surface of the water and remain floating on the surface of the water when the buoy 1 is immersed in the water. .

FIG. 4 schematically shows the internal structural elements of the buoy as they are arranged inside the housing 4 when the buoy is in the storage configuration. As in Figures 5 and 6, the measuring blocks are not shown in Figure 4.

The buoy comprises a floating body 7 initially housed in the housing 4 in the stowed configuration of the buoy and configured to rise to the surface of the water and float on the surface of the water when the buoy 1 is immersed in the water.

The buoy 1 comprises a sonar 110 with negative buoyancy. This sonar 110 is connected to the floating body 7 by a first portion 6a of a dive line comprising two sub-portions 6aa, 6ab. The dive line 6 connects the floating body 7 to a sonar 110 with negative buoyancy via an attachment body 211. More precisely, the first portion 6a connects the floating body 7 to the sonar 110 via an attachment body 211.

The sonar 110 comprises a reception antenna 111 comprising the support body 9, a set of arms 10 carrying acoustic sensors not shown in FIG. 4 in which the set of arms is shown schematically by two diametrically opposed arms for more than clarity.

Portions 6a and 6b are initially folded over.

In the example of FIG. 4, the reception antenna 111 comprises another body 8 connected to the body 9 by a second portion 6b of the diving line 6, the body 8 being connected to the floating body 7 by means of the body 9. As a variant, the body 8 is fixed relative to the body 9. They can be in one piece.

The receiving antenna 111 is deployable. In other words, it is able to pass from a stored configuration of FIG. 4 to a deployed configuration of FIG. 4 so that each of the arms also passes from one

stowed configuration, in which the arms are in a collapsed configuration, to an extended configuration.

The arms 10 are angularly distributed around a reference axis r of the support body 9, that is to say around an axis r fixed relative to the body 10. The arms 10 are articulated to the support body 9. so as to be able to switch from the configuration of a folded configuration to the configuration deployed by moving the arms away from the axis r. More precisely, each arm 10 extends longitudinally from a proximal end EP articulated to the body 9 to a distal end ED which moves away from the axis r during the deployment of the arm 10.

In the embodiment of the figures, the arms 10 pass from the folded configuration to the configuration deployed by pivoting relative to the support body 9. The arms 10 are connected to the support body 9 by a pivot link 41. The axis of each link pivot 41 is tangential to the reference axis r. In other words, it is tangent to a circle centered on the reference axis r and perpendicular to the axis r.

The arms 10 are maintained in the stowed configuration when the buoy 1 is in the stowed configuration shown in Figure 4.

In the particular embodiment of the figures, the arms 10 are telescopic. Each arm 10 comprises a first segment 11 connected to the body 9 and a set of at least one other segment 12 telescopically connected to the first segment 11 so that the arm 10 can be extended. The arms 10 are able to pass from the stored configuration of FIG. 4, in which the arms are in the folded configuration, to the deployed configuration of FIG. 6 by lengthening the arms 10 and rotating the arms 10 relative to the body 9. The arms 10 pass through a so-called elongated configuration shown in Figure 5 in which they are longer than in Figure 4 and in which they are still in the folded configuration.

As visible in Figures 4 to 7, the buoy 1 comprises a stay 13 per arm 10. Each stay 13 is connected on the one hand to an attachment body 211 between the support body 9 and the floating body 7 and on the other hand to one of the arms 10, at a distance from the articulation between the body 9 and the arm 10.

The stays 13 are configured and arranged so as to allow the arms 10 to be pivoted with respect to the body 9 towards the deployed configuration.

As visible in Figure 3c, the floating body 7 comprises an inflatable bag 70 which comes out of the housing 4 and is inflated by an initially compressed gas housed in the buoy, when the buoy 1 is immersed in the water, so that the floating body 7 has a positive buoyancy making it rise to the surface of the water S and remain floating at the level of this surface S during the deployment of the buoy. The floating body 7 comprises a transmitter and / or a receiver 72 of radio waves allowing remote and wireless communication between the buoy 1 and a receiver and / or a remote transmitter as well as a box 71 which can, for example, house equipment. electronic.

As the floating body 7 rises to the surface, the sonar 110 sinks, as does the housing 4. The ED distal end of each arm 10 is initially mechanically coupled to the body 8 so that the arms 10 extend as the body extends. 9 moves away from the floating body 7 to the elongated configuration of FIG. 5.

The diving of the body 9 is stopped by the portion 6a of the diving line which stretches when the floating body 7 floats on the surface of the water. The diving of the body 8 is stopped when the arms are in their extended configuration. The housing 4 continues to dive and therefore comes to release the arms 10 from their folded configuration.

The plunging of the body 8 while the body 7 rises to the surface of the water has resulted in an increase in the vertical distance separating the attachment body 211 from the arms 10, the stays 13 are stretched and then come to pull on the arms 10 upwards by moving the distal ends ED away from the arms 10 of the body 9 and more particularly from the reference axis r to the deployed configuration of FIG. 6.

The arms 10 then extend radially with respect to the reference axis r of the body 9. In other words, the projections of the respective arms in a plane perpendicular to the axis r extend along respective radial axes defined with respect to to this axis.

As a variant, the arms 10 do not extend radially with respect to the reference axis r of the body 9 in the deployed configuration. They can then, for example, be connected to the body 9 by a pivot connection of non-tangential axis to the axis r.

In general, the arms are advantageously inclined relative to the axis r in the deployed configuration.

In the non-limiting case of the figures, the buoy is configured so that the r axis is substantially vertical (parallel to the z axis) when the arms pass from the folded configuration to the deployed configuration. The axis r is the longitudinal axis of the dive line 6 which is stretched along a substantially vertical axis under the effect of differences in buoyancy between the bodies of the buoy.

In the embodiment of the figures, the arms 10 extend upwards. Alternatively, the arms extend downward.

The buoy 1 is shown in its deployed configuration in FIG. 7. The receiving antenna is then in the deployed configuration. The arms 10 and the measuring blocks 60 are shown more precisely, in the deployed configuration, in FIG. 8.

In the particular embodiment of Figures 7 and 8, the arms 10 extend in a plane perpendicular to the axis r of the body in the deployed configuration. As a variant, the arms are inclined relative to the plane perpendicular to the axis r in the deployed configuration.

In the embodiment of the figures, the arms have symmetry of revolution about their respective longitudinal axes. They present here a circular section. As a variant, the arms may have a cross section of another fixed shape substantially over its entire length. The diameter of the section of the arms can vary along the arms, in particular when they are telescopic, in order to allow interlocking of the different sectors of the arms mounted with respect to one another and a sliding of the different sectors with respect to each other. . More generally, the arms are configured so as not to generate a torque of the measuring device 111 about the axis r during a vertical translation of the measuring device in the deployed configuration.

As can be seen in Figures 7 and 8, the measuring blocks 60 carried by the arms 10 extend between the arms 10.

In Figure 9, there is shown a section of Figure 8 along a vertical plane substantially perpendicular to an arm 10, passing through a block of

measurement 60 and tangential relative to the axis r at the level of the measurement block 60.

As can be seen in FIG. 9, each measuring block 60, delimited by a contact surface S with water, generates an individual torque of the reception device 111 around the axis z during a translational movement. of the measuring device, in the deployed configuration, along the vertical axis z in both directions (up and down). These individual torques are directed in the same direction around the z axis so that the set of measuring blocks 60 generates a torque, around the z axis, in the same direction. By contact surface with water is meant a surface intended to be in direct physical contact with water when the measuring device is submerged.

Indeed, as shown schematically in FIG. 9, under the effect of the flow of water on the contact surface S of the measuring block 60 during a vertical upward translation, each measuring block undergoes a force comprising a vertical component V and a horizontal component comprising a tangential component T. This tangential component T generates a so-called individual torque of the measuring device 111 about the axis z.

In the non-limiting example of the figures, the measuring blocks 60 each have a substantially parallelepipedal shape extending between the arms and being inclined, in the deployed configuration, with respect to the axis r which is substantially the vertical axis z in the deployed configuration. This form of the measuring blocks is of course not limiting. The two largest faces of the measuring block 60 are a first face 21 and a second face 22, being water contact surfaces. As a first approximation, the force undergone by the measuring unit during a translation of the measuring device 111 deployed upwards is the force undergone by the first surface 21 and that undergone by the face 22 during a vertical downward movement. . These faces 21 and 22 are inclined with respect to the reference axis r substantially parallel to the z axis and with respect to a substantially tangential horizontal line, the tangential direction is defined with respect to the axis r. This is also the case for their respective normals N1, N2.

In the non-limiting example of the figures, the horizontal component H of the force undergone by the measuring unit during each vertical translation (upward or downward) is the tangential component T.

The tangential components T of the forces undergone by the different measuring blocks 60 are, in the nonlimiting example of the figures, oriented in the same direction because the measuring blocks 60 have, in the deployed configuration, the same inclination with respect to l z axis and with respect to respective tangential axes at the level of the respective measuring blocks.

According to the invention, the measuring device 111 comprises compensation means 161 configured and arranged so as to limit or prevent the rotation of the measuring device 111, in the deployed configuration, around the axis z during a vertical translation. up and / or down. The compensation means 161 oppose the rotational movement of the measuring device which the measuring blocks tend to cause during this vertical movement. In other words, the compensation means 161 are configured and arranged to generate, during a vertical movement of the measuring device 111 in the deployed configuration, a torque of rotation of the measuring device 111 about the z axis, in the opposite direction to that generated by the measuring blocks 60 during the same vertical movement and of intensity such that the total torque undergone by the measuring device around the z axis during the vertical movement of the deployed measuring device exhibits an intensity less than that of the torque of the measuring device generated, around the z axis, by the measuring blocks 60. This makes it possible to limit the rotation of the measuring device around the z axis. For this purpose, the rotational torque generated by the compensation means around the z axis has an intensity less than the intensity of the rotational torque generated by the measuring blocks, the measuring device then always rotates around the z axis but with a lower speed. Alternatively, the rotational torque generated by the compensation means around the z axis has an intensity substantially equal to the intensity of the rotational torque generated by the measuring blocks, the measuring device is then substantially stationary in rotation around the z axis. As a variant, the torque generated by the compensation means around the z axis has an intensity less than

double the intensity of the torque generated by the measuring blocks, the measuring device then rotates in the opposite direction, with respect to a device without compensation means, but with a lower speed.

The invention makes it possible to limit or reduce the rotation of the measuring device induced by the vertical movement and therefore to limit the aforementioned problems linked to the rotation of the measuring device around the axis of rotation. Furthermore, this solution does not require mobility of the measuring blocks 60 in rotation around the longitudinal axis of the arms, which makes it possible to maintain a certain reliability of the device linked to the limitation of the number of moving parts relative to each other. .

Advantageously, the compensation means are configured and arranged so that the torque around the z axis generated by the compensation means 161 is substantially the opposite of the torque around the z axis generated by the assembly. of measuring blocks 60 during vertical movement up and / or down. This makes it possible to avoid the rotation of the measuring device 111 around the axis r under the effect of the vertical movement in the direction (s) concerned.

As can be seen in FIG. 9, the compensation means 161 comprise a set of at least one compensation block 61 delimited by a surface, called the compensation surface S 'intended to be in direct physical contact with water when the measuring device is submerged. The compensation blocks 61 are configured and arranged so as to generate a torque, called the compensation torque, of the measuring device around the z axis in the opposite direction to the rotational torque of the measuring device around the z axis generated by the measuring blocks 60, during a vertical movement of the measuring device in the deployed configuration, upwards and / or downwards, so as to limit the rotational movement of the measuring device 111 around the axis z.

In other words, when the measuring device 111 is in the deployed configuration, each compensation block undergoes, under the effect of the flow of water on its surface during a translation of the measuring device in the deployed configuration according to the z axis, a force comprising a vertical component V '(during an upward vertical movement) and a horizontal component comprising a tangential component T to the z axis directed in the opposite direction to the tangential component T. It is even during a vertical translation of the measuring device deployed along the z axis.

The vertical component V 'is in the same direction as the vertical component V.

In the non-limiting example of the figures, as can be seen more precisely in FIG. 9, each compensation block 61 has essentially the shape of a rectangular parallelepiped and comprises two larger faces 31 and 32 substantially forming the compensation surface S ′. These faces 31 and 32 are inclined, in the deployed configuration, with respect to the reference axis r substantially parallel to the axis z and with respect to a tangential axis defined with respect to the axis r. This is also the case for their respective normals N, N2 '. The tangential axis defined with respect to the r axis is an axis tangent to a circle, centered on the reference axis r and perpendicular to the reference axis r, at the level of the compensation block or of the face considered. In other words, the tangency of the axis to the circle is done at the level of the compensation block or of the face considered. The circle is centered on the reference axis and perpendicular to the reference axis.

As a first approximation, the component T 'of the force undergone by the compensation block during a vertical upward movement of the deployed compensation device is the tangential component of the force undergone by the surface 31 located opposite the flow of l water during this movement. As a first approximation, the component T of the force undergone by the compensation block during a downward vertical movement of the deployed compensation device is the tangential component of the force undergone by the surface 32 located opposite the flow of the water during this movement.

In general, each measuring block advantageously comprises a first contact surface with water having an average normal which, in the deployed configuration, is inclined with respect to the reference axis and with respect to a first tangential axis defined by relative to the reference axis, so as to generate an individual torque of the measuring device around the reference axis r during a translation of the measuring device along the reference axis in one direction. The mean normal to a surface is the sum of the elementary norms

elementary surfaces of the surface. The first tangential axis defined with respect to the r axis is an axis tangent to a circle, centered on the reference axis r and perpendicular to the reference axis r, at the level of the measurement block considered or of the surface considered . It is represented here by the T axis.

When the lift of the measuring block is negligible, the first contact surface with water is substantially the part of the surface of the measuring block oriented in the direction of vertical translation of the measuring device.

In the non-limiting example of FIG. 9, the surface oriented in the direction of vertical translation of the measuring device is substantially the surface 21 during an upward movement and 22 during a downward movement.

Each compensation block advantageously comprises a second contact surface with water having an average normal which, in the deployed configuration, is inclined with respect to the reference axis r and with respect to a second tangential axis defined with respect to the reference axis r, so as to generate an individual compensation torque of the measuring device around the reference axis r during the translation of the measuring device along the reference axis in the same direction. The second tangential axis defined with respect to the r axis is an axis tangent to a circle, centered on the reference axis r and perpendicular to the reference axis r, at the level of the compensation block or of the surface considered. It is here represented by the axis T '.

When the lift of the compensation block is negligible, the contact surface with the water is substantially the surface oriented in the direction of vertical translation of the measuring device

In the non-limiting example of FIG. 9, the surface oriented in the direction of vertical translation of the compensation block is substantially the surface 31 during an upward movement and the surface 32 during a downward movement. .

This applies to different forms of measuring blocks and compensation blocks. These blocks can have the overall shape of a plate having large rectangular surfaces or any other shape, such as elliptical for example.

The surface in direct contact with the water may or may not be flat. It may, for example, have ribs.

The measurement or compensation block may have one or more notches.

These blocks can have a fixed or variable thickness. The thickness can be taken along an axis tangential to an axis of an arm. This thickness can vary along a radial axis defined with respect to the axis of the arm.

At least one measurement unit and / or one compensation unit may be of the “airplane wing” type. Advantageously, a straight line passing through a leading edge and a trailing edge of the compensation block (or of the measurement block) has a normal which, in the deployed configuration, is inclined with respect to the reference axis r and by relative to an axis tangential to the reference axis so as to generate the associated torque. The tangential axis defined with respect to the r axis is an axis tangent to a circle, centered on the reference axis r and perpendicular to the reference axis r, at the level of the considered block or of the considered normal.

Advantageously but not necessarily, as can be seen in FIG. 9, the compensation blocks are configured and arranged so that the horizontal component H undergone by each measuring block 60 and that H 'undergone by each compensation block during the vertical movement towards the up and / or down is substantially tangential, in other words, it only has a tangential component T or T '. This configuration makes it possible to avoid a translation of the device along the radial axis (defined with respect to the z axis).

The average normal to the first contact surface with water of each measuring unit is advantageously included, in the deployed configuration, in a plane comprising an axis parallel to the reference axis r and the first tangential axis defined with respect to the reference axis r. The average normal to the second water contact surface of each compensation block is advantageously included, in the deployed configuration, in a plane comprising an axis parallel to the reference axis r and the second tangential axis defined with respect to the reference axis r.

The measuring blocks 60 are oriented so that each compensation block generates an individual torque of the measuring device 111 in the same direction around the z axis during a translational movement of the measuring device in one direction along the z axis. Moreover, the compensation blocks 61 are oriented so that each compensation block 61 generates an individual torque, called individual compensation torque, of the measuring device 111 around the z axis, in the same direction, opposite to that individual rotational torques generated by the measuring blocks during a translational movement of the measuring device 111 in the same direction along the z axis.

The measuring blocks 60 and the compensation blocks 61 are carried by the arms 10 so as to be driven by the arms 10 during the passage of the arms from their passage from the folded configuration to the stored configuration.

The measuring blocks 60 and the compensation blocks 61 extend between the arms 10. More precisely, each of them and each of the compensation surfaces extends between two adjacent arms, that is to say over a sector. angular formed around the axis r and separating two adjacent arms.

In the particular embodiment of the figures as shown in FIG. 8, each measuring block 60 is fixed on an arm 10 and each compensation block 61 is fixed on an arm 10. This makes it possible to ensure better reliability of the measuring device than if these blocks were mounted movably on the arms, for example pivoting about their respective longitudinal axes.

In the embodiment of the figures, several measuring blocks 60 and several compensation blocks 61 are mounted on each of the arms. As a variant, at least one compensation block and / or at least one measuring block is mounted on each of the arms. For example, the compensation blocks can be mounted on different arms of the measuring blocks. In the particular embodiment of the figures, each arm 10 carries the same number of measuring blocks 60 as of compensation blocks, but some are not visible in FIG. 8.

The compensation and measurement blocks each form a protuberance on one of the arms. This prevents the interlocking of the compensation blocks and the measures one in the other when they are mounted on a telescopic arm, the segments of which are able to interlock with each other. Thus, the adjacent compensation and measurement blocks along the same arm move away from each other when the arm is lengthened. Thus, the different measuring blocks mounted on the same arm are distant from each other in the deployed configuration and these measuring blocks and / or these compensation blocks can be supported on each other in the deployed configuration.

In the embodiment of the figures, each measuring block 60 mounted on an arm forms a protuberance on one of the arms 10, the protrusion moves away from the arm 10 in the same first direction of rotation around the axis z when the device for measure is deployed. In other words, each of the measuring blocks 60 mounted on the same arm forms a protuberance on the arm on the same side of a plane radial to the z axis containing the radial axis of the arm. Each of the compensation blocks 61 mounted on the same arm 10 forms a protuberance on the arm on the other side of the plane radial to the z axis containing the radial axis of the arm, with respect to the measuring blocks 60 mounted on the same. arm 10. In addition,

In the particular embodiment of the figures, each measuring block 60 is associated with a compensation block 61 fixed on the same arm 10, preferably on the same segment 11 or 12 of the arm 10 as the measuring block 60 facing the block. measuring 60 on the other side of a radial plane to the z axis containing the radial axis of the arm 10. The different measuring blocks 60 are associated with respective different compensation blocks 61. Each compensation block 61 is arranged and configured so as to exert an individual modulus compensation torque less than double the individual torque exerted by the measurement unit 60 which is associated with it. This makes it possible, in the case of telescopic arms, to avoid the generation of torsional torques between the various segments of the telescopic arms around the longitudinal axis of the arm. This also makes it possible to limit the generation of torques inside the arm or the arm segment considered around a tangential axis of rotation such as to generate bending of the arms. These two types of couples create stresses at the level of the arms which can generate deformations of the arms liable to degrade the performance of the reception antenna 111, the sensors having to preferably be coplanar or at least have predetermined arrangements with respect to each other. others in the deployed configuration. The proposed configuration also makes it possible to homogenize the axial component of the drag at the level of the arm and to limit the risks of destabilization of the measuring device during the vertical translation of the measuring device. These two types of couples create stresses at the level of the arms which can generate deformations of the arms liable to degrade the performance of the reception antenna 111, the sensors having to preferably be coplanar or at least have predetermined arrangements with respect to each other. others in the deployed configuration. The proposed configuration also makes it possible to homogenize the axial component of the drag at the level of the arm and to limit the risks of destabilization of the measuring device during the vertical translation of the measuring device. These two types of couples create stresses at the level of the arms which can generate deformations of the arms liable to degrade the performance of the reception antenna 111, the sensors having to preferably be coplanar or at least have predetermined arrangements with respect to each other. others in the deployed configuration. The proposed configuration also makes it possible to homogenize the axial component of the drag at the level of the arm and to limit the risks of destabilization of the measuring device during the vertical translation of the measuring device. preferably be coplanar or at least have predetermined arrangements with respect to each other in the deployed configuration. The proposed configuration also makes it possible to homogenize the axial component of the drag at the level of the arm and to limit the risks of destabilization of the measuring device during the vertical translation of the measuring device. preferably be coplanar or at least have predetermined arrangements with respect to each other in the deployed configuration. The proposed configuration also makes it possible to homogenize the axial component of the drag at the level of the arm and to limit the risks of destabilization of the measuring device during the vertical translation of the measuring device.

Advantageously, the compensation block 61 and the measuring block 60 associated with one another are symmetrical with respect to the same vertical tangential plane when the measuring device 111 is deployed.

Furthermore, in the particular embodiment of the figures, the compensation block associated with a measuring block is integral with this measuring block. This ensures rapid assembly of the assembly. As a variant, these two blocks belong to two different parts.

Advantageously, the block comprising the measurement and compensation unit associated with one another integrates means for mounting the measurement and compensation unit on the arm.

As a variant, the measurement and compensation blocks associated with one another are offset along the arm or along the same segment of the arm. However, this solution is less compact and the adjustment of the surfaces of the compensation blocks is more difficult. Moreover, this solution increases the risks of deformation of the arm and of destabilization of the measuring device.

As a variant, the number of compensation blocks is different from the number of measurement blocks. We can even consider a single compensation block.

If the volume available is sufficient, it is possible to provide a single compensation block configured and arranged to generate a torque in the opposite direction to the torque generated by the assembly of

measuring blocks when the measuring device moves up and / or down.

In the particular embodiment of the figures, the measuring blocks and the compensation blocks each have the shape of a plate essentially having the shape of a rectangular parallelepiped comprising two larger faces connected by four lateral faces, one lateral face of which is contiguous to the arm on the entire length of the side face. This form is absolutely not limiting, any other form can be envisaged. The faces of the compensation block are not necessarily plane or parallel two by two. The measuring and compensation blocks are advantageously configured so as not to deform when they are submerged, for example under the effect of the vertical movement of the measuring device.

Advantageously, the measuring blocks 60 and the compensation blocks 61 are mounted on the arms so as to be housed in the housing 4 when the arms are in the stored configuration. This constraint therefore excludes an arrangement of the measurement and compensation blocks so as to be in the horizontal plane of the arms in the deployed configuration.

Thus, advantageously, the measuring blocks 60 and the compensation blocks 61 are for example mounted on the arms so as to be inscribed in a cylinder of axis r delimited by the arms 10, when the arms are in the folded configuration like this. is shown in Figures 10 (without the housing) and 11 (with the housing).

Advantageously, the measuring blocks 60 and the compensation blocks 61 are mounted on the arms 10 so as to be housed, perpendicular to the axis r, in a ring of axis r delimited by the housing 4 and the body 9 in the configuration row.

In the non-limiting embodiment of the figures, the arms 10 deploy upwards and extend in the same substantially horizontal plane in the deployed configuration. The compensation 61 and measurement 60 blocks then extend below the plane of the arms 10, along the z axis, in the deployed configuration.

As a variant, the arms deploy downwards and extend in the same substantially horizontal plane in the deployed configuration. The

compensation and measurement blocks then extend above the plane of the arms, along the axis r.

Advantageously, the different measuring blocks 60 are configured and arranged so as to be subjected to the same tangential component T during a vertical translation of the measuring device 111 deployed in one direction and / or in the opposite direction. This is advantageously also the case for the different compensation blocks and the tangential component T ′. This allows a certain ease of production of the measuring device 111.

To this end, in the nonlimiting embodiment of the figures in which the arms 10 are arranged in a substantially horizontal plane in the deployed configuration, the measuring blocks 60 have the same outer envelope, that is to say the same first surface. contact 21 and the same second contact surface 22. Moreover, as can be seen in FIG. 9, the measuring blocks 60 are arranged so as to form the same angle α oriented around the axis of the arm 10 on which they are. respectively mounted with respect to the horizontal plane H in the deployed configuration. This makes it possible to ensure a coplanar positioning of all the measuring blocks 60 and a linear positioning of the measuring blocks mounted on the same arm. It is the same for the compensation blocks 61 which have the same outer envelope, that is to say the same first compensation surface 31 and the same second compensation surface 32. Furthermore, the compensation blocks 61 are arranged so as to form the same radial angle b oriented around the axis of the arm. 10 on which they are respectively mounted relative to the horizontal plane in the deployed configuration. Moreover, as the corresponding compensation and measurement blocks are arranged opposite one another, in order to generate rotational torques of the same intensity around the axis r, their first compensation and contact surfaces have the same surface, their second compensation and contact surfaces have the same surface and they form, around the axis r, angles a and b equal. that is to say the same first compensation surface 31 and the same second compensation surface 32. Furthermore, the compensation blocks 61 are arranged so as to form the same radial angle b oriented around the axis of the arm 10 on which they are respectively mounted relative to the horizontal plane in the deployed configuration. Moreover, as the corresponding compensation and measurement blocks are arranged opposite one another, in order to generate rotational torques of the same intensity around the axis r, their first compensation and contact surfaces have the same surface, their second compensation and contact surfaces have the same surface and they form, around the axis r, angles a and b equal. that is to say the same first compensation surface 31 and the same second compensation surface 32. Furthermore, the compensation blocks 61 are arranged so as to form the same radial angle b oriented around the axis of the arm 10 on which they are respectively mounted relative to the horizontal plane in the deployed configuration. Moreover, as the corresponding compensation and measurement blocks are arranged opposite one another, in order to generate rotational torques of the same intensity around the axis r, their first compensation and contact surfaces have the same surface, their second compensation and contact surfaces have the same surface and they form, around the axis r, angles a and b equal. the compensation blocks 61 are arranged so as to form the same radial angle b oriented around the axis of the arm 10 on which they are respectively mounted relative to the horizontal plane in the deployed configuration. Moreover, as the corresponding compensation and measurement blocks are arranged opposite one another, in order to generate rotational torques of the same intensity around the axis r, their first compensation and contact surfaces have the same surface, their second compensation and contact surfaces have the same surface and they form, around the axis r, angles a and b equal. the compensation blocks 61 are arranged so as to form the same radial angle b oriented around the axis of the arm 10 on which they are respectively mounted relative to the horizontal plane in the deployed configuration. Moreover, as the corresponding compensation and measurement blocks are arranged opposite one another, in order to generate rotational torques of the same intensity around the axis r, their first compensation and contact surfaces have the same surface, their second compensation and contact surfaces have the same surface and they form, around the axis r, angles a and b equal.

It should be noted that these characteristics are not limitative, the dimensions, shapes and arrangement of the compensation blocks on the arms may differ from those described above while generating the same individual rotation torque opposed to the individual rotation torque generated by the control block. associated measurement.

In the embodiment of the figures, the dimension of each compensation block 61 along the axis of the arm 10 on which it is mounted is greater than the dimension of the measurement block which is associated with it, while its tangential dimension is greater than that of the block. measurement in the row configuration of FIG. 11. In other words, the compensation block is dimensioned so as to occupy a smaller opening sector than the associated measurement block around the axis r, in particular in the row configuration . Indeed, as visible in Figure 11, each measuring block 60 leaves an insufficient space free between the arm 10 on which it is mounted and the adjacent arm 10 so that the compensation block can have a tangential dimension as large as the block. of measurement.

As a variant, the measuring device comprises at least one measuring block and / or a compensation block is fixed to a cable carried by adjacent arms and configured and arranged so as to be in tension in the deployed configuration.

At least one compensation block can comprise at least one means of the measurement chain other than an acoustic sensor. At least one compensation block may comprise an amplifier and / or an analog-to-digital converter and / or an acoustic wave transmitter, that is to say a means configured to emit acoustic waves. At least one compensation unit can include at least one sensor capable of measuring another physical quantity such as, for example, a water salinity sensor for measuring the salinity of the water and / or a temperature sensor for measuring the temperature of the water. 'water. As a variant, the compensation block does not have the means of a measuring chain.

In the embodiment of the figures, the measuring device 111 also comprises acoustic transmitters 171 attached to the dive line 6 as visible in FIG. 7. The receiving antenna 111 is interposed between the transmitters 171 and the floating body 7 on the line 6. These acoustic transmitters 171 are initially housed in the box 4.

The main cause of the rotation of our system during vertical movements is that the measuring blocks are tilted.

This inclination is for example due to the need to integrate the measuring blocks in a limited volume in a stored configuration of the measuring device. The solution is therefore to implement similar surfaces making it possible to create a counter torque to limit or reduce the torque of the measuring device around the axis r.

The proposed solution ensures good stability of the measuring device even in the presence of swells or changes in depth. In fact, this solution makes it possible to limit or even cancel the rotational movements of the measuring device by the measuring blocks during a vertical movement of the measuring device which may for example be due to the swell or to a change in depth. ordered. The compensation surfaces are, by nature, small, of the order of that of the compensation blocks. Consequently, they have a small horizontal surface which results in a small increase in drag and therefore does not disturb the changes in depth, in particular the speed during changes in depth.

The proposed solution is easy to implement. It also has a limited cost and occupies a very low volume, which is essential in the field of air-dropping buoys which are disposable.
CLAIMS

1. Measuring device intended to be immersed in water comprising a set of arms and a reference axis, the measuring device being adapted to be in a deployed configuration in which the arms extend radially around the axis of reference, the measuring device comprising a set of measuring blocks carried by arms of the set of arms and each comprising an acoustic wave sensor, the set of measuring blocks being configured and arranged so as to generate a torque of rotation of the measuring device around the reference axis during a vertical translation of the measuring device in the deployed configuration, each measuring block of the measuring assembly comprising a first contact surface with water intended for be in direct physical contact with water and oriented,in the deployed configuration, so that it undergoes, under the effect of the flow of water on the first contact surface with the water during the vertical translation, a first force comprising a vertical component and a component horizontal comprising a tangential component generating an individual torque of the measuring device around the reference axis, the individual rotation pairs generated by the measuring blocks of the measuring assembly being oriented in the direction of the torque, the measuring device comprising compensation means configured and arranged so as to generate another torque of the measuring device around the reference axis during vertical translation,the other torque being directed in the opposite direction to the torque and having an intensity less than twice that of the torque, the compensation means comprising a set of at least one compensation block comprising a second contact surface with the water intended to be in direct physical contact with the water and oriented, in the deployed configuration, so that it undergoes, under the effect of the flow of water on the second surface of contact with the 'water during vertical translation, a second force comprising a vertical component and a horizontal component comprising a tangential component generating an individual compensating rotational torque of the measuring device around the reference axis, thethe compensation means comprising a set of at least one compensation block comprising a second water contact surface intended to be in direct physical contact with the water and oriented, in the deployed configuration, so that it is subjected , under the effect of the flow of water on the second surface in contact with the water during vertical translation, a second force comprising a vertical component and a horizontal component comprising a tangential component generating an individual torque of rotation compensation of the measuring device around the reference axis, thethe compensation means comprising a set of at least one compensation block comprising a second water contact surface intended to be in direct physical contact with the water and oriented, in the deployed configuration, so that it is subjected , under the effect of the flow of water on the second surface in contact with the water during vertical translation, a second force comprising a vertical component and a horizontal component comprising a tangential component generating an individual torque of rotation compensation of the measuring device around the reference axis, theso that it undergoes, under the effect of the flow of water on the second surface in contact with the water during vertical translation, a second force comprising a vertical component and a horizontal component comprising a tangential component generating an individual compensating rotational torque of the measuring device around the reference axis, theso that it undergoes, under the effect of the flow of water on the second surface in contact with the water during vertical translation, a second force comprising a vertical component and a horizontal component comprising a tangential component generating an individual compensating rotational torque of the measuring device around the reference axis, the

individual compensation torque being oriented in the opposite direction to the torque.

2. Measuring device according to the preceding claim, wherein the other torque has an intensity substantially equal to the intensity of the torque.

3. Measuring device according to any one of the preceding claims, in which the compensation block is arranged and configured so that the force undergone by the compensation block has a horizontal component comprising only a tangential component.

4. Measuring device according to any one of the preceding claims, in which the set of at least one compensation block and the set of measuring blocks is fixed to the set of arms.

5. Measuring device according to any one of the preceding claims, in which a compensation block is associated with each measurement block, the compensation block associated with a measurement block being fixed to the same arm as the measurement block and being configured and arranged so as to generate, during the vertical translation, an individual torque of the measuring device substantially in the opposite direction of an individual torque generated by the measuring unit during the vertical translation.

6. Measuring device according to the preceding claim, wherein the individual rotational torque generated by the compensation block is substantially opposed to the individual rotational torque generated by the measuring block.

7. Measuring device according to any one of claims 5 to 6, wherein the arms are telescopic and each comprise several segments capable of sliding relative to one another, the compensation block being fixed on the same one.

segment as the associated measurement block.

8. Measuring device according to any one of claims 5 to 7, wherein the measuring block is integral with the associated compensation block.

9. Measuring device according to any one of the preceding claims, in which the compensation unit occupies, around the reference axis r, an angular sector of opening less than an angular sector occupied by the measuring device. with which it is associated.

10. Measuring device according to any one of the preceding claims, in which the set of measuring blocks comprises a sub-set of measuring blocks mounted on the same arm, the measuring blocks of the sub-assembly being arranged in the same way. the same side of the radial plane to the reference axis containing the axis of the arm.

11. Measuring device according to the preceding claim, wherein each compensation block mounted on the arm is disposed on the other side of the radial plane.

12. Measuring device according to any one of the preceding claims, wherein the second contact surface with water having an inclined average normal, in the deployed configuration, with respect to the reference axis and with respect to an axis. tangential to the reference axis, so as to generate the individual compensating rotational torque of the measuring device around the reference axis.

13. Measuring device according to the preceding claim, wherein the second contact surface with water is oriented in the direction of vertical translation.

14. Measuring device according to any one of

preceding claims, wherein the compensation block has a substantially parallelepiped plate shape.

15. A measuring device according to any one of claims 1 to 11, wherein a straight line passing through a leading edge and a trailing edge of the compensation block has an inclined normal, in the deployed configuration, with respect to to the reference axis and with respect to a tangential axis, defined with respect to the reference axis, so as to generate the individual torque of the measuring device around the reference axis.

16. A measuring device according to any one of the preceding claims, wherein the first contact surface with water has an inclined mean normal, in the deployed configuration, with respect to the reference axis and with respect to an axis. tangential, defined with respect to the reference axis, so as to generate the individual torque of the measuring device around the reference axis.

17. Measuring device according to any one of the preceding claims, in which at least one compensation block incorporates a measuring element other than an acoustic sensor.

18. Measuring device according to any one of the preceding claims, in which the compensation unit has no acoustic sensor.

19. A measuring device according to any preceding claim, wherein the measuring device is adapted to be in a row configuration in which the arms are inscribed in a cylinder whose axis is the reference axis, the blocks measuring device and the compensation means being configured and arranged so as to be housed in said cylinder when the measuring device is in the stored configuration.

20. Measuring device according to any one of

preceding claims, wherein the arms extend in a plane substantially perpendicular to the reference axis in the deployed configuration

21. An acoustic buoy comprising a measuring device according to any one of the preceding claims.

22. Acoustic buoy according to the preceding claim, comprising a floating body and a dive line to which are connected the floating body and the arm, the buoy being configured so that the floating body floats on the surface of the water and the line. diving extends longitudinally along a vertical axis substantially coincident with the reference axis when the measuring device is in the deployed configuration.