FR3140468A1 - Device for transmitting signals between a fixed part and a rotating part - Google Patents

Abstract

The invention relates to a signal transmission device comprising: a fixed part (1); a rotating part (2) mounted to move in rotation on the fixed part (1) around an axis (Z); a signal transmission cable (10) having a first end (10.1) connected to a first electrical circuit carried by the fixed part, and a second end (10.2) connected to a second electrical circuit carried by the rotating part. The cable (10) comprises a plurality of signal transmission elements arranged parallel to each other to form a signal transmission sheet, the sheet comprising a section positioned to have a width substantially parallel to the axis of rotation and to wrap around the axis (Z) of rotation ABSTRACT FIGURE: Fig. 3B

Description

Device for transmitting signals between a fixed part and a rotating part

The present invention relates to the transmission of signals between a fixed part and a rotating part.

BACKGROUND OF THE INVENTION

In the field of surveillance (civil or military), it is known to use unmanned aerial vehicles, more commonly referred to as drones.

For this purpose, a drone is generally equipped with an optronic turret comprising a base, a rotating body pivotally mounted on the base about a bearing axis, and an optronic ball pivotally mounted on the rotating body about a site axis. The rotating body is rotated about the bearing axis by first drive means, and the optronic ball is rotated about the site axis by second drive means. The optronic ball comprises at least one camera intended for aerial photography.

The optronic turret further comprises a control unit comprising a control module configured to control the first and second drive means, and a processing module configured to control the camera.

The control unit is arranged in the base and is connected, via wired communication means, to the camera and to the first and second drive means. The wired communication means comprise a shielded cable having a first end connected, via a first connector secured to the base, to the control unit, and a second end connected, via a second connector secured to the rotating body, to the second drive means and to the camera.

The cable typically comprises a plurality of insulated conductive wires which are arranged parallel to each other to form a strand of conductive wires. The conductive wires are wrapped in a protective sheath provided with an internal shielding coating.

When the rotating body rotates relative to the base, the cable is subjected to torsional forces which can cause premature wear of the insulation of each of the conductive wires with an orange effect, but also of the protective sheath whose shielding wires can pierce said insulation and cause unwanted short circuits.

What is more, a high-altitude drone is required to operate in a particularly cold environment where the temperature can reach -55 degrees Celsius. At this temperature, the cable and its insulation harden, which accelerates the degradation of the cable subjected to torsional forces and hinders the rotation of the rotating body.

To overcome these drawbacks, one solution is to use a rotating collector. However, such a solution is particularly expensive and is therefore only used for rotations greater than 360 degrees.

SUBJECT OF THE INVENTION

The invention therefore aims to propose a device for transmitting a signal between a fixed part and a rotating part making it possible to at least partially overcome the aforementioned drawbacks.

• une partie fixe portant un premier circuit ;
• une partie tournante montée mobile en rotation sur la partie fixe autour d’un axe, et portant un deuxième circuit ;
• un câble de transmission de signaux ayant une première extrémité raccordée au premier circuit et une deuxième extrémité raccordée au deuxième circuit.

For this purpose, the invention proposes a signal transmission device comprising:

• a fixed part carrying a first circuit;
• a rotating part mounted so as to rotate on the fixed part around an axis, and carrying a second circuit;
• a signal transmission cable having a first end connected to the first circuit and a second end connected to the second circuit.

According to the invention, the cable comprises a plurality of signal transmission elements arranged parallel to each other to form a signal transmission sheet, the sheet comprising a section positioned to have a width substantially parallel to the axis of rotation and to wrap around the axis (Z) of rotation.

Thus, a rotation of the rotating part causes the sheet to wind or unwind around the axis of rotation in the direction of rotation of said rotating part, i.e. the transmission elements bend around an axis perpendicular to their length: this makes it possible to limit the torsional forces undergone by the transmission elements during said rotation. In addition, the force required to bend the transmission elements is relatively low so that the sheet does not exert high stresses at its connection to the electrical circuits.

According to a particular characteristic of the invention, the first end and/or the second end of the sheet comprises a fold forming an oblique angle with a longitudinal edge of said sheet.

In particular, the angle is approximately equal to 45 degrees.

According to another particular characteristic of the invention, the sheet extends inside the fixed part, between a bottom of the fixed part and a bottom of the rotating part, the bottom of the fixed part and the bottom of the rotating part extending perpendicular to the axis of rotation.

In particular, the bottom of the fixed part and the bottom of the rotating part are spaced apart by a distance slightly greater than a width of the sheet so as to ensure an axial circumscription of said sheet.

According to another particular characteristic of the invention, the device comprises a peripheral wall extending around the wound section of the sheet to contain the latter and ensure a radial circumscription of the sheet.

In particular, the peripheral wall delimits an opening for passage of the sheet, the first end of the sheet extending outside the volume while the second end extends inside said volume.

In particular, the opening comprises two substantially parallel guide ramps which each extend in the extension of one end of the peripheral wall and define an angle of attack of the sheet in the volume.

The invention also relates to an optronic turret comprising such a device, the fixed part forming a base of the turret and the mobile part forming a rotating body of said turret.

The invention also relates to a vehicle (D) comprising such an optronic turret.

The invention will be better understood in light of the following description, which is purely illustrative and not limiting, and must be read in conjunction with the appended drawings, among which:

there is a schematic view of a vehicle according to the invention, here a drone;

there is a perspective view of an optronic turret equipping the drone illustrated in the ;

there illustrates a first state of winding of a sheet for transmitting electrical signals between a fixed part and a rotating part of the optronic turret illustrated in ;

there is a view identical to the , illustrating a second state of winding of the sheet;

there is a view identical to the , illustrating a third state of winding of the sheet.

DETAILED DESCRIPTION OF THE INVENTION

In reference to the , a fixed-wing D drone, having a fuselage equipped in the front part with an optronic turret T intended here for aerial photography.

The optronic turret T comprises, as illustrated in the , a base 1, a rotating body 2 and an optronic ball 3.

Base 1 is fixed to the underside of the front part of the fuselage of drone D.

The rotating body 2 comprises a rotating base 2a and a support 2b fixed to the rotating base 2a.

The rotating base 2a is pivotally mounted on the base 1 about a bearing axis Z, and is driven in rotation about the bearing axis Z by first drive means. The first drive means comprise a first electric motor M1 which is arranged inside the base 1 and which allows a rotation of the rotating body 2 about the bearing axis Z, here ranging from 0 degrees to 360 degrees.

The support 2b comprises two arms 2.1 extending opposite each other. Each of the arms 2.1 extends from an external circumference of the rotating base 2a, parallel to the bearing axis Z.

The optronic ball 3 is spherical in shape and extends between the two arms 2.1 of the rotating body 2. The optronic ball 3 is pivotally mounted about a site axis X which is perpendicular to the bearing axis Z, and is driven in rotation about the site axis X by second drive means. The second drive means comprise a second electric motor M2 which is arranged inside the rotating body 2 and which allows a rotation of the optronic ball 3 about the site axis X, ranging for example from +20 degrees to -180 degrees (preferably from +20 degrees to -100 degrees) in elevation relative to the plane perpendicular to the bearing axis Z and comprising the site axis X.

• une caméra 3.1 sensible à la lumière visible, comprenant un capteur de type CMOS (acronyme de l’anglais« Complementary Metal Oxide Semiconductor ») ; et
• une caméra 3.2 thermique infrarouge de type LWIR (acronyme de l’anglais« Long Wavelength InfraRed »), comprenant un capteur de type microbolomètre (sans système de refroidissement), ou une caméra thermique infrarouge de type MWIR (acronyme de l’anglais« Medium Wavelength InfraRed ») comprenant un capteur avec un système de refroidissement.

The optronic ball 3 comprises a plurality of optronic components comprising here:

• a 3.1 camera sensitive to visible light, including a CMOS (acronym for “Complementary Metal Oxide Semiconductor” ) type sensor; and
• a 3.2 LWIR ( Long Wavelength InfraRed ) type infrared thermal camera, comprising a microbolometer type sensor (without cooling system), or a MWIR ( Medium Wavelength InfraRed) type infrared thermal camera comprising a sensor with a cooling system.

Each of the sensors of the 3.1, 3.2 cameras is arranged behind a group of optical lenses and filters to manage the dynamics of the analyzed scene.

Optionally, the optronic components also include a SWIR ( Short Wavelength InfraRed ) thermal camera.

The optronic ball 3 also includes a stabilization device associated with each of the sensors of the cameras 3.1, 3.2, and optionally a light-emitting diode projector.

The optronic turret T also comprises a control unit UC comprising a control module configured to control the first and second drive means, and a processing module configured to control the optronic components. The control unit UC is arranged inside the base 1 and comprises one or more electronic cards on which are mounted electronic components such as a microcontroller, a processor, an FPGA (acronym for "Field Programmable Gate Array" ), an ASIC (acronym for "Application Specific Integrated Circuit" ), a DSP (acronym for "Digital signal processor" ), etc.

The control unit UC is connected, via wireless communication means, to a human-machine interface (not shown) which here comprises a screen and a computer positioned on the ground. The control module is arranged to receive from the human-machine interface, via the wireless communication means, control signals from the first and second motors M1, M2 making it possible to orient the optronic ball 3 along the elevation axis X and the bearing axis Z. The processing module is arranged to send to the human-machine interface, via the wireless communication means, data representative of the signals delivered by the sensors of the cameras 3.1, 3.2. The human-machine interface thus makes it possible to interact with the optronic turret T.

The control unit UC is connected, via wired communication means, to the first and second motors M1, M2 as well as to the cameras 3.1, 3.2.

With reference to FIGS. 3A-3C, the wired communication means comprise a flat cable 10 for transmitting electrical signals between a first electrical circuit carried by the base 1 and connected to the control unit UC, and a second electrical circuit carried by the rotating body 2 and connected to the second motor M2 and to the cameras 3.1, 3.2, so as to connect the control unit UC to the second motor M2 and to the cameras 3.1, 3.2. The cable 10 extends inside the base 1 and comprises a plurality of conductive wires (for example made of copper) which are arranged parallel to each other and coated with insulating material to form a sheet of insulated conductive wires. The sheet 10 has a substantially constant width and comprises a section whose width extends parallel to the axis in bearing Z and which is curved around the axis in bearing Z in order to be able to wind substantially in a spiral around said axis, between a bottom of the base 1 and a bottom of the rotating base 2a, these bottoms extending orthogonally to said axis in bearing Z. The bottom of the base 1 and the bottom of the rotating base 2a are spaced apart by a distance slightly greater than the width of the sheet 10, such that they form axial stops for the winding of the sheet 10 around the axis in bearing Z. The bottom of the base 1 and the bottom of the rotating base 2a thus ensure an axial circumscription of the sheet in the base 1.

A first end 10.1 of the sheet 10 extends in a first direction D1 substantially orthogonal to the axis in bearing Z to connect to the control unit UC via a first connector of the first circuit. The first end 10.1 of the sheet 10 is thus immobile with respect to the control unit UC, and therefore with respect to the base 1.

A second end 10.2 of the sheet 10, opposite the first end 10.1, extends in a second direction D2 substantially parallel to the axis in bearing Z to connect, via a second connector of the second circuit of the rotating body 2. For this purpose, the second end 10.2 connects to the curved section of the sheet 10 by a fold 10.3 ( ) forming an angle substantially equal to 45 degrees with a longitudinal edge of said sheet 10, such a fold 10.3 making it possible to avoid twisting of the sheet 10 during rotation of the rotating base 2a relative to the base 1. The second end 10.2 of the sheet 10 is stationary with respect to the rotating base 2.

It will be noted that the distance separating the first end 10.1 from the axis in bearing Z is greater than that separating the second end 10.2 from said axis in bearing Z.

The optronic turret T further comprises a flange 20 delimiting, with the bottom of the base 1 and the bottom of the rotating base 2a, a volume V in which the sheet 10 is wound around the axis in bearing Z. To do this, the flange 20 comprises a substantially tubular sleeve 21 centered on the axis in bearing Z and secured, by one end, to a collar 22 fixed to the base 1.

The sleeve 21 extends between the bottom of the base 1 and the bottom of the rotating base 2a and comprises a peripheral wall 21.1 substantially centered on the axis in bearing Z so as to form a radial stop for the unwinding of the sheet 10 around said axis in bearing Z. The sleeve 21 thus ensures a radial circumscription of the sheet 10 in the volume V.

The peripheral wall 21.1 is split so as to delimit an opening 21.2 for the passage of the sheet 10, the first end 10.1 of the sheet 10 extending outside the volume V while the second end 10.2 of the sheet 10 extends inside said volume V. The opening 21.2 comprises two guide ramps 21.3 each extending in the extension of one end of the peripheral wall 21.1, outside the volume V. The ramps 21.3 are substantially parallel and define an angle of attack of the sheet 10 in the volume V. This angle of attack is chosen so as to limit the stresses inside the sheet 10 and to promote the winding and unwinding of the sheet 10 inside the volume V according to the direction of rotation of the rotating body 2. The base 1 preferably comprises an element for immobilizing the sheet 10 in the vicinity of the entry opening of the sheet 10 in the volume V. The immobilization element comprises for example a pin on which a clamping bar is fixed, the sheet 10 being pinched between the pin and the clamping bar.

Figures 3A-3C illustrate the winding/unwinding of the sheet 10.

There illustrates a first winding state of the sheet 10 corresponding to a first angular position of the rotating body 2 relative to the base 1. The sheet 10 is partially supported against the peripheral wall 21.1 of the flange 20 and has a first winding diameter d1.

There illustrates a second state of winding of the sheet 10 corresponding to a second angular position of the rotating body 2 relative to the base 1. The sheet 10 is slightly in abutment against the peripheral wall 21.1 of the flange 20 and has a winding diameter d2 which is less than the first winding diameter d1. Thus, the passage of the rotating body 2 from the first angular position to the second angular position causes a first winding of the sheet 10 and a reduction in the support of said sheet 10 against the peripheral wall 21.1 of the flange 20. Conversely, the passage of the rotating body 2 from the second angular position to the first angular position causes an unwinding of the sheet 10 and an increase in the support of said sheet 10 against the peripheral wall 21.1 of the flange 20.

There illustrates a third state of winding of the sheet 10 corresponding to a third angular position of the rotating body 2 relative to the base 1. The sheet 10 is only very slightly in abutment against the peripheral wall 21.1 of the flange 20 and has a third winding diameter d3 which is less than the second winding diameter d2. Thus, the passage of the rotating body 2 from the second angular position to the third angular position causes a third winding of the sheet 10 and a reduction in the abutment of said sheet 10 against the peripheral wall 21.1 of the flange 20. Conversely, the passage of the rotating body 2 from the third angular position to the second angular position causes an unwinding of the sheet 10 and an increase in the abutment of said sheet 10 against the peripheral wall 21.1 of the flange 20.

Of course, the invention is not limited to the embodiment described but encompasses any variant falling within the scope of the invention as defined by the claims.

Although the sheet 10 here comprises a plurality of conductive wires allowing the transmission of electrical signals, it can also comprise a plurality of elements allowing the transmission of signals of other nature: optical (for example optical fibers), fluidic (for example fluidic conduits), etc.

Flange 20 is optional.

The first end 10.1 of the sheet 10 may comprise a fold substantially identical to the fold 10.3 of the second end 10.2. The first end 10.1 of the sheet 10 must then be connected to the base 1 in a direction substantially parallel to the axis in bearing Z. Conversely, the second end 10.2 of the sheet 10 may not comprise a fold 10.3. The second end 10.2 of the sheet 10 must then be connected to the rotating base 2a in a direction substantially perpendicular to the axis in bearing Z.

The optronic ball 3 may include a multispectral camera.

The T optronic turret of the invention can be used on vehicles of all types such as land, surface or submersible aquatic vehicles, fixed or rotary wing aerial vehicles, etc., piloted or not.

Claims (10)

Signal transmission device comprising:

• a fixed part (1) carrying a first circuit;
• a rotating part (2) mounted so as to rotate on the fixed part (1) around an axis (Z) of rotation, and carrying a second circuit;
• a signal transmission cable (10) having a first end (10.1) connected to the first circuit, and a second end (10.2) connected to the second circuit;

characterized in that the cable (10) comprises a plurality of signal transmission elements arranged parallel to each other to form a signal transmission sheet, the sheet comprising a section positioned to have a width substantially parallel to the axis of rotation and to wrap around said axis of rotation. Device according to claim 1, wherein the first end (10.1) and/or the second end (10.2) of the sheet (10) comprises a fold (10.3) forming an oblique angle with a longitudinal edge of said sheet. Device according to claim 2, in which the angle is substantially equal to 45 degrees. Device according to any one of the preceding claims, in which the sheet (10) extends inside the fixed part (1), between a bottom of the fixed part (1) and a bottom of the rotating part (2), the bottom of the fixed part and the bottom of the rotating part extending perpendicular to the axis (Z) of rotation. Device according to claim 4, in which the bottom of the fixed part (1) and the bottom of the rotating part (2) are spaced by a distance slightly greater than a width of the sheet (10) so as to ensure an axial circumscription of said sheet (10). Device according to any one of the preceding claims, comprising a peripheral wall (21.1) extending around the wound section of the sheet (10) to contain the latter and ensure a radial circumscription of the sheet (10) in a volume (V). Device according to claim 6, in which the peripheral wall (21.1) delimits an opening (21.2) for the passage of the sheet (10), the first end (10.1) of the sheet extending outside the volume (V) while the second end (10.2) extends inside said volume (V). Device according to claim 7, in which the opening (21.2) comprises two substantially parallel guide ramps (21.3) which each extend in the extension of one end of the peripheral wall (21.1) and define an angle of attack of the sheet (10) in the volume (V). Optronic turret (T) comprising a device according to any one of claims 1 to 8, the fixed part (1) forming a base of the turret and the mobile part (2) forming a rotating body of said turret. Vehicle (D) comprising an optronic turret (T) according to claim 9.