Technical field of the invention:

The invention relates to a towed communication and observation vehicle that enables underwater vehicles to communicate, locate and observe without coming up/approaching the water surface.

In particular, the invention relates to a towed communication and observation vehicle for underwater systems, which is connected to the underwater vehicle with a cable and is located on the water surface.

State of the Art:

Communication for underwater vehicles is a capability that bears many technical challenges but is equally important. Electromagnetic signals lose their energy in a very short distance under water. For this reason, communication with electromagnetic signals is only possible with an antenna that can be raised above the water surface.

Many unmanned underwater vehicles (REMUS, SPARUS, AUV62AT etc.) have antennas attached to the hull and extending upwards. Said underwater vehicles can use these antennas by going to the surface. The long-range DM2A4 ER torpedo also has a telescopic antenna it uses coming to the surface at low speed.

In order to use the antennas attached to the hull, the underwater vehicle must come very close to the surface or come to the surface. This is problematic for many reasons. First of all, the surface conditions may not be suitable for the vehicle to approach the surface. If the sea state is 4 or higher, controlled navigation of a torpedo-sized underwater vehicle will not be possible.

The speed of said underwater vehicle will also prevent it from reaching the surface. The Froude number of a 6-meter underwater vehicle at a speed of 15 knots is calculated as 1 .0. Navigating with such a Froude number is only possible with planning hull forms and navigating with a torpedo type hull is not possible in terms of energy or control. In addition, the capabilities expected from the vehicle conflict with the requirement of approaching the surface. A sonar system on the surface will not be functional, and propulsion systems will not be able to work, especially at high speeds.

The invention that is the subject of the application no "US7230881 B2" in the state of the art comprises a smaller underwater vehicle released from the submarine and carrying a communication antenna on its upper part. Said underwater vehicle may have a hydrodynamic form and control system towed by the submarine while en route, or it may be in the form of a buoy that will stay on the water surface with only buoyancy force. The second solution, in the form of a buoy, cannot be used while the submarine is en route. The first solution, which has a hydrodynamic form suitable for underwater, needs to be close enough to the surface to bring the antenna out of the water surface. In the case of turbulent seas, this is only possible if the submarine is cruising at very low speeds.

The invention that is the subject of the application no "US8443750B2" in the state of the art comprises a communication unit that is connected to the underwater vehicle with a cable and completely sits on the surface of the underwater vehicle when it is not deployed. The form of this unit is such that it allows the unit to plane on the water surface. The form is designed as a planing trimaran, and it is expected that the unit will enter the planing cruise regime as the speed increases. Indeed, at 4.5 knots, the Froude number exceeds 1 .0 for a 0.5-meter-long form. It is expected that the form will enter the planing regime from these speeds. The biggest problem here is that such a small hull is always being pulled over the sea surface, which has a certain amount of turbulence. The forces acting on the planning hulls by the water are directly dependent on the contact angle with the water surface and the size of the contact surface. It is projected that a communication unit of said dimensions will be under highly variable loads even under slightly turbulent surface conditions and will be thrown under and over the surface in an uncontrolled manner.

Therefore, unlike previous technical solutions, there is a need for a system that can be used in situations where the underwater vehicle it is connected to is travelling at much higher speeds and the sea surface is more turbulent. As a result, due to the negativities described above and the inadequacy of the existing solutions on the subject, it was necessary to make a development in the relevant technical field.

The aim of the invention

The invention relates to a towed communication and observation vehicle that enables underwater vehicles to communicate, locate and observe without coming up/approaching the water surface.

The most important aim of the invention is to reduce the slamming interaction with the water surface to a negligible level by means of the surface piercing wing structure. In this way, it enables the underwater vehicle to be used in situations where the underwater vehicle is travelling at much higher speeds and the sea surface is more turbulent.

Another aim of the invention is to enable the use of sensors that collect visual data (camera, range finder, etc.) by placing them on the communication unit, since the communication unit is more stable. In this way, healthy visual data can be obtained from the surface.

Another aim of the invention is to ensure that healthy visual data taken from the surface can be evaluated by the underwater vehicle and can be transferred to other elements in the field with the facilities provided by the communication unit.

Another aim of the invention is to provide less resistance both on the water surface and under water by means of the communication unit form. In this way, it provides to reduce the difficulties encountered during the release from the underwater vehicle and the retracting to the underwater vehicle.

The structural and characteristic features of the invention and all its advantages will be understood more clearly by means of the figures given below and the detailed description written with reference to these figures. For this reason, the evaluation should be made by taking these figures and detailed description into consideration. Of

Figure -1 ; The drawing that gives the appearance of the towed communication and observation vehicle for underwater systems that is the subject of the invention.

Figure -2; The drawing that gives the view of the communication unit that is the subject of the invention.

Figure -3; The drawing that gives the view of the communication unit, that is the subject of the invention, on the water surface.

Figure -4; The drawing that gives the view of the passive balancing capability of the system in case the immersion depth of the communication unit, that is the subject of the invention, changes.

Reference numbers:

110. Communication unit

111. Body

112. Fin

120. Cable

130. Storage and fixing station

140. Drum mechanism

200. Underwater vehicle of the invention

The invention relates to a towed communication and observation vehicle that enables underwater vehicles to communicate, locate and observe without coming up/approaching the water surface. The towed communication and observation means for underwater systems that is the subject of the invention comprises communication unit (110), cable (120), storage and fixing station (130) and drum mechanism (140).

The communication unit (110) enables the underwater vehicle (200) to communicate by being released to the water surface the underwater vehicle (200) and retracted back. The communication unit (1 10) awaits in the storage and fixing station (130) when not in use. On the communication unit (110), there are fins (1 12) that enable it to move away from the underwater vehicle (200) and the storage station (140) when it is to be released. The fins (1 12) ensure that the communication unit (120) is lifted towards the surface as it moves away from the underwater vehicle (200).

The body (1 1 1 ) of the communication unit (1 10) comprise a pair of controlled fins (1 12) near its lower edge. The body (1 1 1 ) is in a surface piercing form. When the communication unit (120) reaches the water surface, the fin (112) part of the body remains in the water. The communication unit (1 10) is in the form of an inverse-T wing. When the communication unit (1 10) reaches the surface, the part that pierces the water surface allowing it to follow the underwater vehicle (200) by piercing the water surface is in the form of a surface piercing wing.

The communication unit (1 10) comprises a series of sensor groups on the unit in order to monitor its status and, if necessary, to control the position of the communication unit (1 10). The sensors may be an inertial measurement unit to calculate the angular orientation of the unit, a wetness sensor to calculate the position of the unit relative to the water surface, or a pressure sensor. The sensor (113) also provides the monitoring of the amount of cable released.

The communication unit (1 10) comprises components thereon such as a GPS module and a data link/radio module to fulfil the communication, positioning and observation capability. The positioning capability to be obtained by means of the GPS module will enable a vehicle with long travel times to correct its own location calculation. Positioning accuracy to be obtained with tactical level inertial measurement units is significantly reduced at long travel times and distances. By means of the position correction capability provided by the invention, the underwater vehicle using the invention will be able to position precisely in missions spanning very long distances and time.

The communication unit (110) comprises a communication module that enables the vehicle to communicate with other elements in the field without surfacing. With the communication module located on the communication unit (1 10), it is possible to update the mission in the field and to share the data obtained by the underwater vehicle. The relevant capability means that many tactical capabilities such as patrolling, navigation, swarm organization, intelligence gathering can be imparted to the underwater vehicle.

There is an electro-optical sensor on the communication unit (1 10), which is used to take images over water. The data/image received with this unit located at the end of the communication unit can be transferred to the underwater vehicle from the data line on the cable for processing, or it can be transmitted to other elements in the field by the unit that already has communication capability. In this way, the underwater vehicle has the ability to collect visual data without coming to the surface of the water. The modular structure of the communication unit (1 10) allows the use of task-specific and interchangeable payloads.

The communication unit (1 10) is retracted to its compartment in the underwater vehicle (200) when its mission is terminated. In the retraction process, the cable (120) is wound by the drum mechanism (140) and the unit is brought closer to the underwater vehicle (200). In the meantime, depth and orientation control is performed with the fins on the communication unit (110). The communication unit (1 10), which is finally retracted to the storage and fixing station (130), is fixed here.

The cable (120) provides the control of the distance of the communication unit (1 10) to the underwater vehicle (200) (releasing, retraction, and towing) and the exchange of energy and data between the communication unit (110) and the underwater vehicle (200). The cable (120) provides the necessary force for retracting the communication unit (1 10) on the water surface. The force acting on the communication unit (1 10) by the cable (120) has components both in the movement direction of the underwater vehicle (200) and downwards. The force acting in the movement direction of the underwater vehicle (200) is balanced by the drag force acting on the communication unit (1 10). The downward force acting on the communication unit (1 10) by the cable (120) is balanced with the lift force provided by the fins (1 12) on the communication unit (1 10). It is possible to control the attack angles of the fins (1 12) with an actuator system in order to create the vertical force balance. The relative vertical position of the unit with respect to the water surface can be adjusted by adjusting the angle of attack of the fins (112) according to the amount of protrusion of the system from the water surface.

In an embodiment of the invention, the vertical balance of the system is provided passively. In this alternative, the fins (1 12) stay at a fixed angle on the communication unit (1 10) while cruising. The free body diagram of the communication unit (1 10) during cruise is given in Figure 4. In Figure-4 (a), while the communication unit is towed on the water surface, the horizontal position of the fins (1 12) is behind the cable (120) connection point of the communication unit (110). In Figure-4 (a), the equalities are calculated by Equation-1 . Here (h) is the vertical distance between the horizontal force (Fy) acting on the communication unit by the cable and the centre of the drag force (D) acting on the communication unit. (I) is the horizontal distance between the vertical force (Fz) acting on the communication unit by the cable and the centre of the lift force (L) acting on the communication unit.

Ml = DxhO, M2 = LxIO, Ml = M2 Equation-1

In Figure-4 (b), the drag force (D) acting on the communication unit (110) at constant speed will increase with the increase of the submersion depth of the unit. At the same time, the point of impact of the drag force (D) acting on the unit will shift upwards. Since the communication unit (1 10) is pulled horizontally by the cable (120) with the force Fy in the meantime, the moment (M1 ) trying to tilt the communication unit (110) against the flow direction will increase and the unit will rotate in the opposite direction of cruise. In Figure-4 (b), the equalities are calculated by Equation-2.

Ml = Dlxhl, M2 = LOxIO, Dl > D0, hl > h0, Ml > M2

Equation-2 In the case of Figure-4 (c), the angle of attack of the fins (112) will increase and the lift force (L) produced by the fins will increase. While the increase in the lift force will move the unit upwards, the moment (M2) that tries to rotate the unit in the flow direction will increase due to the fact that the fins (1 12) are behind the body. In Figure-4 (c), the equalities are calculated by Equation-3.

Ml = Dlxhl, M2 = Llxll, 11 > 10, hl > hO, M2 > Ml Equation-3

In the case of the system approaching the surface in Figure-4 (d), D and M1 will decrease and in turn, the fin (1 12) angle of attack will decrease as the system tilts towards the direction of cruise. In Figure-4 (d), the equalities are calculated by Equation-4.

Ml = DxhO, M2 = LxIO, M2 = Ml

Equation-4

Because of this dynamic relationship, passive stabilization of the system is possible without being dependent on a control loop.

The storage and fixing station (130) is integrated with the body of the underwater vehicle (200) or is located outside the body of the underwater vehicle (200), depending on the design of the underwater vehicle (200), and provides the storage and fixing of the communication unit (1 10). The storage and fixing station (130) ensures that the communication unit (1 10) is fixed and stored on the underwater vehicle (200) when not in use. When the communication unit (1 10) is to be released, the storage and fixing station (130) opens the apparatus used for fixing the communication unit in the storage and fixing station (130) and ensures that the cable (120) is unwinded by the drum mechanism (140). The drum mechanism (140) provides controlling the unwinding of the cable (120).

In one embodiment of the invention, the conceptual design for an underwater vehicle (200) with a diameter of 533 mm is given in Figure-1 . Although the working principle of the system is the same, the design of the communication unit (1 10) and the storage and fixing station (130) will differ according to the characteristics of the carrier platform.