DE102024116484B3 - Sonar measuring device - Google Patents

Abstract

The present invention discloses a sonar measuring device for detecting underwater structures, comprising a sonar sensor (5) and a radio-controlled aircraft (1), wherein the radio-controlled aircraft (1) has a platform (2), and the sonar sensor (5) is connected to the platform (2). The sonar measuring device comprises a ground receiving unit (11) with an antenna (12), a satellite navigation receiver (13) for detecting a stationary reference position, and a measuring unit (14) coupled to the antenna (12) and the satellite navigation receiver (13). The ground receiving unit (11) is designed to radio-receive the sonar data currently measured by the sonar sensor (5) upon immersion in a body of water (G) to be examined, to georeference this sonar data with the stationary reference position and the current position of the radio-controlled aircraft (1), and to photorealistically display the currently received and georeferenced sonar data on a screen. An elongate flexible connecting element (6) comprising an electrical cable connection (7) is connected at its first end to the platform (2) of the radio-controlled aircraft (1) and at its opposite end to a submersible body (8), and the sonar sensor (5) is attached to the submersible body (8), the sonar sensor (5) being connected to the radio-controlled aircraft (1) via the electrical cable connection (7).

Description

The invention relates to a sonar measuring device for detecting underwater structures with a sonar sensor and a radio-controlled aircraft, wherein the radio-controlled aircraft has a platform and the sonar sensor is connected to the platform.

Sonar sensors are used to detect underwater structures. Acoustic signals are emitted by a sonar sensor, and the signal responses reflected by the structures are received and evaluated by the original signal from the solar sensor.

Remotely controlled, automated aircraft are used for reconnaissance and imaging of large areas and stretches of land. The use of rotary-wing aircraft has also become established. In addition to aircraft equipped with a propeller to generate lift, so-called multicopters are increasingly being used. Due to the use of multiple rotors, multicopters (also called drones) are characterized by their stable flight characteristics, ease of handling, high payload, and the ability to remain in any position.

Remotely controlled or semi-automated aircraft can be equipped with camera systems for the visual range as well as systems for imaging the infrared, near-infrared, or hyperspectral wavelength range. The use of laser-based scanners is also known. Such imaging sensors used by aircraft have so far been limited to imaging surfaces above water. Multicopter systems are also known that land on the water surface and submerge an optical camera attached to the underside of the platform into the water. This allows for visualization of the area very close to the multicopter, provided visibility underwater is sufficient.

It is also known to use echo sounders on the underside of helicopters. These are submerged in the sea surface and emit highly modulated, long-wave sound waves (beams). If these signals are reflected by rock formations, large marine mammals, or manned underwater vehicles, the signals are recorded by hydrophones and examined by sonar experts for the presence of known signatures. The reflected signal strength can be used to calculate the distance to the helicopter, a compass bearing, and the intensity. Imaging sonar systems are primarily used in hydrography. Systems permanently installed on sounding vessels are used to determine water depth or to regularly monitor obstacles along access roads. High-resolution multi-beam systems or side-scan sonars are used on autonomous robotic underwater drones for imaging wreck sites, underwater formations, or to create highly accurate topographical maps. Autonomous underwater vehicles operate without connection to a mother ship or land station. After the mission is completed, the collected sonar data is transferred from the autonomous underwater vehicle to powerful evaluation computers and must undergo post-processing using navigation data. Such systems are not capable of real-time operation. Remotely controlled surface vehicles are used, which deploy high-resolution sonars remotely or autonomously in harbor areas or the oceans. Unprocessed live sonar data from the installed sonars can be transmitted over long distances via a connection to satellite transmission systems or other wireless network connections. Adequate infrastructure is required to launch these surface vehicles into the water.

In the field of fishing, photorealistic 2D multibeam echo sounder systems are sometimes used to locate schools of fish and individual animals. The transmitter and receiver unit is mounted on the hull of the fishing boat itself and is thus moved through the water. The image to be interpreted is evaluated in a separate computer unit and can then be projected onto a screen. Multicopter-based surveying systems for bathymetric measurements are also known. In these systems, a sonar sensor attached to a rotary-wing aircraft is lowered into a body of water. A radar altimeter is used to ensure a constant height of the rotary-wing aircraft above the water surface.

JP 2017-219 514 A discloses a fish shoal search system with an unmanned aerial vehicle and a ship, which includes a control device for the unmanned aerial vehicle. The control device has a communication device for communicating with external communication equipment via a communication channel. The unmanned aerial vehicle includes a photographing device for photographing an external part of its own machine; a buoyancy body that lands and floats on the sea; and a communication device for communicating with the control device via the communication channel. Information transmitted from the unmanned aerial vehicle via the communication channel include position information of the unmanned aerial vehicle and video information photographed by the photographing device, and the control device includes a display device for displaying a video based on the video information.

WO 2018/070586 A1 Describes a drone for detecting a school of fish or underwater objects. The drone lands on the water while flying over water to detect a school of fish, underwater objects, or various information, such as water temperature, and transmits this information to a depot ship or a ground control center. Efficient use of underwater information is to be enabled by the drone being formed by a buoyant main body, a plurality of auxiliary buoyant bodies, and a propeller device. The buoyant main body enables the drone to float on the water. A transducer (ultrasonic detector) is attached to the lower end of the main body. The auxiliary buoyant bodies are connected to side surfaces of the buoyant main body. The propeller device has a rotary vane at the upper end of the auxiliary buoyant body to enable flight.

JP 2021-049 985 A discloses an underwater surveying system and method capable of quickly and easily conducting underwater surveying at a variety of positions in various locations. The underwater surveying system includes an unmanned aerial vehicle capable of flying by remote control; a measuring unit coupled to the unmanned aerial vehicle; and a floating body for floating the unmanned aerial vehicle and the measuring unit on the water surface. The measuring unit includes a camera for underwater photography that submerges underwater while floating on the water surface. The measuring unit is at least capable of measuring underwater geographic information, including underwater camera images, and recording or transmitting the measurement result while floating on the water surface. The unmanned aerial vehicle is capable of moving on the water surface by rotating a rotary wing while floating on the water surface.

DE 10 2023 102 820 B3 discloses a sonar measuring device for detecting underwater structures using a sonar sensor and a radio-controlled rotary-wing aircraft. A ground receiving unit is provided with a satellite navigation receiver for detecting a stationary reference position. The ground receiving unit is designed to radio-receive the sonar data currently measured by the sonar sensor when immersed in a body of water to be examined, to georeference the sonar data with the stationary reference position and the current position of the rotary-wing aircraft, and to photorealistically display the currently received and georeferenced sonar data on a screen. Sonar measurements are taken in a temporarily stationary state by landing the rotary-wing aircraft on the water surface, with the rotors continuing to run at reduced power.

JP 2021-054 378 A discloses a water bottom shape measuring device that measures a three-dimensional shape of a water bottom by positioning a three-dimensional shape measuring part to generate three-dimensional shape information, and generates a water bottom shape as water bottom shape information indicated by a coordinate position on the earth by a water bottom shape information generating part based on the three-dimensional shape information and the positioning information. A housing in which the three-dimensional shape measuring part is housed has a floating body that exerts buoyancy. The buoyancy of the floating body is controlled. When an underwater part including the housing floats on a water surface by an unmanned aerial vehicle and moves the underwater part along the water surface, by reducing the weight of the housing exerted on the unmanned aerial vehicle by the buoyancy of the floating body, a load exerted on the unmanned aerial vehicle can be reduced compared to a case where the underwater part including the housing is moved by the unmanned aerial vehicle in a state positioned in the air.

The object of the present invention is to provide an improved sonar measuring device for detecting underwater structures with a sonar sensor and a remote-controlled rotary-wing aircraft.

The object is achieved with the sonar measuring device having the features of claim 1. Advantageous embodiments are described in the subclaims.

It is proposed that the sonar measuring device comprises a ground receiving unit with an antenna, a satellite navigation receiver for detecting a stationary reference position and a measuring unit coupled to the antenna and the satellite navigation receiver, wherein the ground receiving unit is designed for radio reception of the sonar data currently measured with the sonar sensor when immersed in a body of water to be examined, for georeferencing this sonar data with the stationary reference position and the current position of the radio-controlled aircraft and for photorealistic display of the currently received and georeferenced sonar data on a screen.

An elongated flexible connector comprising an electrical cable connection is connected at its first end to the platform of the radio-controlled aircraft and at its opposite end to a submersible. The sonar sensor is attached to the submersible, and the sonar sensor is connected to the radio-controlled aircraft via the electrical cable connection.

The radio-controlled aircraft is transported via the ground unit to the deployment site, where the sonar sensor attached to the submersible body is submerged in the water. The submersible body hangs from a flexible connecting element, which can be a line or wire, for example, and includes an electrical cable with electrical leads. The sonar sensor is connected by cable to electronics on the platform in order to transmit the sonar sensor data to the electronics via wire and from there wirelessly forward it in real time to the ground receiving unit. The submersible body ensures that the sonar sensor is submerged in the water. For this purpose, the submersible body can preferably have a density of less than 1 g/ ^cm³ and/or be a hollow body, such as a tube that is open on both sides and has a hollow interior.

The interactive control of the radio-controlled aircraft is achieved by the sonar measuring system comprising a ground receiving unit with an antenna, a satellite navigation receiver for detecting a stationary reference position, and a measuring unit coupled to the antenna and the satellite navigation receiver. The ground receiving unit is designed to radio-receive the sonar data currently measured by the sonar sensor when immersed in a body of water to be examined, to georeference this sonar data with the reference position and the current position of the radio-controlled aircraft, and to photorealistically display the currently received and georeferenced sonar data on a screen.

The ground receiving unit and the stationary reference position enable the current position and/or attitude of the radio-controlled aircraft to be recorded with high precision. This allows movements caused by surface movements of the water to be recorded and compensated for more accurately than with a simple radar altimeter. The highly precisely georeferenced sonar data can be transmitted from the radio-controlled aircraft to the measuring unit of the ground receiving unit in real time via radio data signal transmission, where it can be immediately input and evaluated.

This enables better control of the radio-controlled aircraft by feeding the evaluated photorealistic sonar data back as a control variable from the ground receiving unit into control signals that are transmitted to the radio-controlled aircraft via the antenna of the ground receiving unit in order to change the position and/or attitude of the aircraft.

By using a photorealistic imaging sonar sensor, which emits groups of pulses at different frequencies, allowing sonar measurements to be performed with a wider bandwidth, it is possible to detect underwater structures in photorealistic detail. This eliminates the need for expert optical analysis of sonar signatures that require interpretation. Instead, the currently measured underwater structures can be immediately displayed on a screen, immediately recognized by the operator, and used for interactive control of the radio-controlled aircraft to efficiently move the sonar probe to a subsequent measurement position.

The radio-controlled aircraft may have a position and/or attitude sensor and be configured to automatically determine the current position of the aircraft in real time from the position and/or attitude currently measured with the position and/or attitude sensor with reference to the stationary reference position. Using the stationary reference position, the accuracy of the aircraft's position and/or attitude determination can be improved by using this reference position as a reference value for the parameters measured locally in the aircraft with its position and/or attitude sensor.

For example, with a so-called real-time kinematics (RTK), one or more geodetic receivers can be set up to determine stationary reference points, which are used by the radio-controlled aircraft as reference points. These can be satellite navigation receivers (e.g., GPS, GLONASS, etc.), preferably using several of the navigation satellites. Received frequencies are transmitted to determine the influence of the ionosphere on the satellite signal and the resulting position error. By transmitting the position error from the ground receiving unit to the radio-controlled aircraft, or a position signal corrected using the position error, the precision of the determination of the position and/or attitude in the aircraft can be significantly improved by applying the position error and/or a position signal corrected using the position error to the position and/or attitude signals measured in the aircraft.

The ground receiving unit can have a radio base station, and the platform of the radio-controlled aircraft can have a radio communication unit. The radio communication unit and the radio base station can be configured for bidirectional radio communication in order to send control commands from the measuring unit to the radio-controlled aircraft and to send measured sensor data and position and/or attitude data of the aircraft from the aircraft to the base station. This allows the aircraft to be remotely controlled by radio from the ground receiving unit. The bidirectional transmission enables instantaneous evaluation of the measured sensor data in the ground receiving unit or after display on a screen there by the remote-controlling operator, thus providing feedback for the needs-based control of the position and/or attitude of the aircraft and the attached sonar probe.

The radio-controlled aircraft can be a rotary-wing aircraft with a number of rotors on top of the platform and a loading structure on the bottom of the platform. This allows for the use of a stable, lightweight, and reliably controllable aircraft using radio control.

The rotorcraft may have buoyancy devices attached to its landing structure. These devices ensure that the rotorcraft does not lose control upon contact with water, but is instead carried along the water surface by the buoyancy devices. This applies not only in calm waters without significant wave action, but also during larger surface movements or sporadic disturbances.

The sonar measuring system can be configured to control the remotely piloted aircraft so that sonar measurements are taken while towed. This allows the submersible body with its attached sonar sensor to be towed through the water, even in high winds, waves, and strong water currents, to examine underwater areas.

The submersible body can be a rod-shaped weight element. The density of the weight element should be less than 1 g/ ^cm³ , thus ensuring submersion with reduced buoyancy. The rod-shaped weight element can be a solid rod. A hollow tube is also conceivable, which has the advantage of allowing water to flow through it when submerged. This stabilizes the underwater position, especially close to the water surface when towing through the water. This is particularly advantageous at higher towing and/or current speeds.

The sonar sensor can be arranged at a distance from the submersible. For this purpose, the sonar sensor can be attached to the submersible by at least one web. The web can, for example, be a fin, i.e., a plate protruding from the submersible. This stabilizes the submersible, with the attached sonar sensor, in the transverse direction as it is towed through the water by the inflow surface on both sides, and stabilizes its weight in the direction of gravity, so that the sonar body protrudes downwards from the submersible toward the water surface, as far as possible in the direction of gravity. The sonar body can serve as a kind of keel bulb for the fin, which acts as the keel of the submersible.

The fin can be chamfered at the leading edge facing the elongated connecting element. This improves the airflow conditions.

It is advantageous if the transition between the sonar sensor and the bridge, such as a fin, has an outwardly open cavity that is flooded with water when submerged. This ensures that the sonar sensor submerges, and the weight force remains so low compared to a filled ballast body that the submerged body floats below the water surface and, when pulled over the elongated connecting element, does not surface or sink to the bottom of the water.

The rod-shaped weight element can have a first end face and a diametrically opposite second end face. The elongated, flexible connecting element can be attached to the first end face of the rod-shaped weight element. This exerts a tensile force in the longitudinal direction of the submersible body, allowing the submersible body to be pulled through the water on a stable path even under the influence of currents.

The submersible body can have at least one flow guide element. This ensures stable guidance of the sonar sensor through the water, even in strong currents, waves, and high wind loads. A flow guide element can be located at one end of the submersible body. The flow guide element can, for example, have a cavity through which water flows in the direction of travel of the submersible body.

It is conceivable that a shorter hollow flow guide tube is attached to a hollow tubular submersible body, parallel to the submersible body. The flow guide tube can be arranged on the side facing away from the sonar sensor, the side facing the sonar sensor, and/or on both sides perpendicular to the web or fin.

At the front of the submersible body, adjacent to the attachment area of the elongated connecting element, flow guide surfaces can protrude transversely to the extension direction between the submersible body and the sonar sensor on both sides as flow guide elements. For this purpose, for example, two attachment arms can protrude from the submersible body in diametrically opposed directions, with the flow guide surfaces each connected to one of the attachment arms.

The submersible body, the bridge, such as the fin, and/or other parts such as the hollow housing for connecting the sonar sensor to the fin can be made of carbon fiber reinforced plastic. This material is lightweight, stable, and has a specific density of approximately 1.5 g/cm³, which is greater than the density of water at 1 g/ ^cm³ , allowing it to submerge below the water surface. Stainless steel, on the other hand, with its specific weight (i.e., density) of approximately 8 g/cm³, would submerge significantly more and induce a significantly higher tensile load on the elongated connecting element to be towed through the water just below the water surface in a submerged state.

Preferably, the elongated, flexible connecting element is arranged at the first end face of the submersible body, and the flow guide element is arranged at the diametrically opposite second end face. This allows the movement path of the submersible body through the water to be further stabilized.

• 1 - Skizze einer Sonar-Messeinrichtung;
• 2 - schematische Seitenansicht eines Tauchkörpers mit über eine Finne daran angebundenem Sonarsensor;
• 3 - schematische Draufsicht auf den Sonarsensor mit Tauchkörper und Strömungsleitflächen.

The invention is explained in more detail below using an exemplary embodiment with the accompanying drawing. It shows:

• 1 - Sketch of a sonar measuring device;
• 2 - schematic side view of a submersible with a sonar sensor attached to it via a fin;
• 3 - schematic top view of the sonar sensor with submersible body and flow guide surfaces.

1 shows a sketch of a sonar measuring device that has a radio-controlled aircraft 1 in the form of a rotary-wing aircraft. In the illustrated embodiment, this rotary-wing aircraft 1 is a drone with a platform 2, which has several rotors 3 arranged on its upper surface, distributed around a circumference. These rotors are each driven by a motor and can be individually controlled.

On the underside of the rotorcraft 1 there is a landing structure 4 on which the rotorcraft 1 is supported in its landing position.

A sonar sensor 5 protrudes from the underside of the platform 2 and is connected to the platform 2. This sonar sensor 5 is connected to the platform 2 of the aircraft 1 by an elongated, flexible connecting element 6. The connecting element 6 can be, for example, a rope, a wire, or a similar flexible connecting element 6. The connecting element 6 comprises an electrical cable connection 7 with lines that can be used to transmit signals from the sonar sensor 5 to the aircraft 1 and, optionally, also electrical energy from an energy storage device of the aircraft 1 to the sonar sensor 5.

This landing structure 4 can have buoyancy bodies A. This ensures that the rotorcraft 1 touches down safely and remains stable on the surface of the body of water G even when the flight mode is exited, e.g., due to wave action. In this way, the rotorcraft 1 can also be deliberately landed on the water surface at desired measurement positions in order to measure the underwater environment with the sonar sensor 5 extending into the body of water G. This temporary stationary state can save energy. The flight mode requires significantly more electrical energy, which is limited by the payload and the limited charging capacity of the batteries. Surveying in successive, temporarily stationary states in which the rotorcraft 1 touches down on the water surface requires a higher energy requirement only in the flight states for moving the rotorcraft 1 to a measurement position. This position can then be changed gradually or continuously in order to explore a larger area of water. The change in position can preferably be achieved by a temporary transition to the flight state.

In order for the rotorcraft 1 to return from the loading state on the water surface to flight state can be brought without this being prevented by movement of the rotorcraft 1, which is detected as a disturbance and is induced by the moving water surface, the rotors 3 continue to operate at a speed that is energy-saving and does not cause the drone 1 to take off into the flight state. The control system of the rotorcraft 1 interprets the fact that the rotors 3 continue to run as meaning that the rotorcraft 1 is still in the flight state. This deactivates the control mechanisms of the control system which prevent a landed rotorcraft 1 from taking off when movement of the rotorcraft 1 is detected. The transition from the takeoff state to the flight state of rotorcraft 1 regularly requires a defined stable (stationary) position. By continuing to run the rotors 3, the rotorcraft 1 remains in the flight state, even if it is not held by the lift of the rotors 3, but by the buoyancy bodies A on the landing structure 4 in a state that can only be moved or moved by the water movement (ie a quasi-stationary state for the sonar measurement).

If the sonar measurement is carried out as planned in the flight condition, the buoyancy bodies A continue to ensure that the rotorcraft 1 is in a stable condition even in the event of unplanned contact with water, from which the flight condition can be reached again by continuing to operate the rotors 3 and taking off by increasing the speed of the rotors 3.

The sonar measuring device is designed to carry out a towed measurement.

For this purpose, an elongated flexible connecting element 6, which includes an electrical cable connection 7, is connected at its first end to the platform 2 of the radio-controlled aircraft 1 and at its opposite end to a submersible body 8. The sonar sensor 5 is attached to the submersible body 8. The sonar sensor 5 is connected to the radio-controlled aircraft 1 via the electrical cable connection 7.

The submersible body 8 can be designed as a rod-shaped weight element, as shown. This means that the submersible body 8 with its sonar sensor 5 does not float in the water, but rather submerges.

The sonar sensor 5 can be arranged at a distance from the submersible body 8, as shown. For this purpose, the sonar sensor 5 can be attached to the submersible body 8 with at least one web 9. A torsion-resistant attachment is achieved with two webs 9 spaced apart from each other.

The submersible body 8, designed as a rod-shaped weight element, can have a first end face and a diametrically opposite second end face. This provides a flow body with a longitudinal extension direction, wherein the submersible body 8 can be pulled through the water in the longitudinal extension direction on a stable trajectory.

The elongated, flexible connecting element 6 can be attached to the first end face of the rod-shaped weight element. A flow guide element 10 can optionally be arranged at the diametrically opposite second end face. This will ensure even more stable guidance of the submersible body 8 through the water.

Furthermore, the sonar measuring device has a ground receiving unit 11 with an antenna 12, a satellite navigation receiver 13 for detecting a stationary reference position and a measuring unit 14 coupled to the antenna 12 and the satellite navigation receiver 13.

With the help of the satellite navigation receiver 13, time signals from navigation satellites N are received, and the reference position of the satellite navigation receiver 13 is determined from the associated transit times. If the at least one stationary satellite navigation receiver 13 receives the time signals from the navigation satellites N on multiple frequencies or receives and evaluates time signals from different navigation systems, position errors caused in particular by disturbances in the ionosphere can be corrected.

The ground receiving unit 11 is further configured to radio-receive the sonata data currently measured by the sonar sensor 5 when the rotorcraft 1 is positioned over a body of water G. For this purpose, the sonar sensor 5 protruding from the rotorcraft 1 submerges into the body of water to detect echo signals reflected by the sonar sensor 5 from underwater structures S or objects or living beings O present in the body of water by emitting signals from the sonar sensor 5. These special data are then transmitted without delay in real time from the radio communication unit 15 of the rotorcraft 1 to the ground receiving unit 11.

For this purpose, the ground receiving unit 11 has a radio base station 16 configured for bidirectional radio communication. The sonar data currently measured by the sonar sensor 5 while immersing in a body of water to be examined is transmitted to the ground receiving unit 11. They can be georeferenced with the position and/or attitude data already measured using the position and/or attitude sensor 17 of the rotary-wing aircraft 1. These sonar data are thus georeferenced by the current position of rotorcraft 1 and also by the stationary reference position.

For this purpose, the rotorcraft 1 has at least one position and/or attitude sensor 17 for detecting the current position and/or attitude of the rotorcraft 1. This can also be a satellite navigation receiver. Alternatively or additionally, it is also conceivable to determine the position and attitude using acceleration sensors and/or angle sensors, Hall sensors, and the like, which determine a relative position and/or attitude change. Starting from the stationary reference position, the georeferencing of the sensor data can thus also be determined using the relative position and/or attitude changes of the rotorcraft 1.

The ground receiving unit 11 has a screen 18 for displaying the currently measured sonar data. It is also configured for remote control of the rotary-wing aircraft 1, for example, using a joystick 19 to transmit control commands from the joystick 19 via the radio base station 16 to the radio communication unit 15 of the rotary-wing aircraft 1.

Using the position and/or attitude sensors 17 of the rotorcraft 1, the surface movement of the body of water G or the movements of the rotorcraft 1 together with its solar probe 5 caused by the surface movement of the body of water can optionally be determined. These can be detected based on the correlating position and/or attitude changes of the rotorcraft 1, which differ from the attitude changes caused by the control and wind influences.

For this purpose, for example, a frequency transformation of the position and/or attitude signals can be performed in order to determine these environmental influences from the frequencies correlating with the surface movement of the body of water G. This allows the rotorcraft 1 to be controlled so that its position and altitude above the water surface can be adjusted despite the surface movement of the body of water G in order to achieve a desired immersion depth of the solar sensor 5.

The instantaneous transmission of the sonar data to the ground receiving unit 10 and the display of the sonar data on the screen 18 allows the operator to remotely control the rotary-wing aircraft 1 in such a way that the desired positioning of the solar sensor 5 is achieved in order to obtain the most complete and usable underwater image of the body of water G possible.

This provides a real-time imaging sonar system that can be deployed to the scene remotely or semi-autonomously via the rotary-wing aircraft 1. The photorealistic underwater sonar system is deployed georeferenced by the radio-controlled rotary-wing aircraft 1 to quickly and effectively detect underwater structures and even current underwater events.

This allows complex underwater structures in a body of water G to be imaged in real time. Due to the size and maneuverability of the rotorcraft 1, the sonar measuring system can operate in confined spaces that are inaccessible by conventional methods (helicopter, boat, etc.). This allows even areas along densely vegetated shorelines or within power plants to be reached. It is even possible to fly the system through forests, below the treetops, to the deployment site.

This enables targeted deployment in areas where life and limb are at risk. For example, flooded areas with strong currents can be searched for obstacles and people needing rescue, or water surfaces even if contaminated with munitions and mines. Deployment in waters contaminated with chemicals, biological agents, nuclear waste, etc. is also conceivable.

Secure real-time radio transmission of sonar data can be achieved in the 5 GHz frequency range over a distance of at least 650 meters. The ground receiving unit 11, with its antenna 12, is then positioned at a maximum distance of this distance from the body of water G to be examined.

The radio transmission and operation of the sonar measuring device is independent of the remote control or the power supply of the flying rotorcraft 1. This allows the sonar measuring device to be operated in conjunction with different rotorcraft 1 with sufficient payload.

The electronics mounted on the platform of the rotorcraft 1, including the radio communication unit 15 and the sonar sensor 5, can be detachably attached to the platform 2 of the rotorcraft 1 by means of fastening elements in order to equip a suitable rotorcraft 1 with a measuring system as required.

The combination of a rotorcraft 1, for example a multicopter (drone), and a sonar system is independent of the remote control or the supply voltage and is easy to transport, fast Ready for use, quickly arrives at the detection site, and provides geodata of the location. The sonar measuring system is easy to maintain and cost-effective, reducing the risk to life and limb during sonar measurements in waterways.

2 shows a schematic side view of a diving body 8 with a sonar sensor 5 connected to it via a fin 22 forming the web 9.

The immersion body is a tube which is hollow in the interior and open at the end faces, providing a cavity 20 through which water can flow when immersed.

In the bow area, the elongated flexible connecting element 6, which includes an electrical cable connection 7, is attached to the submersible body. Flow guide surfaces 21 can protrude from the submersible body 8 on both sides as flow guide elements 10 for stabilization. Thus, when a tensile force is exerted by the elongated flexible connecting element 6 on the bow of the submersible body 8, a buoyancy force is generated by the water flowing along the flow guide surfaces 21, which keeps the submersible body 8 as horizontal as possible, just below the water surface.

In the stern area of the submersible body 8, a fin 22 protrudes from the submersible body 8. The fin 22 can be conically tapered toward the sonar sensor 5 on the front side facing the bow of the submersible body 8. A cavity 23 open toward the stern and floodable with water can be present in the transition between the fin 22 and the sonar sensor 5. This supports the alignment of the sonar sensor 5 in the direction of gravity to the waterbed without significantly increasing the weight of the submersible assembly.

The sonar sensor 5, together with the floodable cavity 23, is closed off towards the bow by a curved flow nose 24 which tapers towards the bow.

A flow guide tube 25 can be provided in the stern area as a further flow guide element 10. This can be arranged on the side of the submersible body 8 diametrically opposite the sonar sensor 5 or the fin 22. The flow guide tube 25 is open at the opposite ends and is flowed through by the water as the submersible assembly is towed through the water. This allows an approximately horizontal position with a movement path that is as straight as possible, corresponding to the longitudinal direction of the tubular submersible body 8. The movement path only follows a curved path when transverse forces are applied by the elongated, flexible connecting element 6, when a change of direction is desired and imposed.

To attach the elongated, flexible connecting element 6 to the submersible body 8, a fastening web 26 can be attached to the upper side of the submersible body 8. This fastening web extends in the longitudinal direction of the submersible body 8 from the bow to the stern area and can have several fastening openings 27 spaced apart from one another. This allows the attachment point of the connecting element 6 on the submersible body 8 to be variably adjusted, for example, to adapt the force introduction point to the prevailing flow conditions of the body of water and to achieve the most stable position possible for the submersible assembly in the body of water when towing through the body of water.

3 shows a schematic top view of the sonar sensor 5 with the submersible body 8 and the flow guide surfaces 21 projecting from the submersible body 8 on both sides, transversely to the direction of extension of the sonar sensor 5. It can be seen that mounting arms 28 project from the submersible body 8 in diametrically opposite directions in the bow area. The flow guide surfaces 21 are attached to the mounting arms 28 at a distance from the submersible body 8. They are plate-shaped and can each have an optional bevel on the outer leading edges. The edges of the flow guide surfaces 21 can be angular or, preferably, rounded.

It is conceivable that the flow guide surfaces 21 are flat or curved in the longitudinal direction in the manner of a wing and/or transversely to the longitudinal direction of the diving body 8 in order to impart a desired lift force, downforce or lateral holding force.

List of reference symbols

1

radio-controlled aircraft / rotary-wing aircraft

2

platform

3

rotors

4

Landing structure

5

Sonar sensor

6

elongated flexible connecting element

7

electrical cable connection

8

Submersible body

9

web

10

Flow guide element

11

Ground reception unit

12

antenna

13

Satellite navigation receiver

14

measuring unit

15

Radio communication unit

16

radio base station

17

Position and/or attitude sensor

18

Screen

19

Joystick

20

flow-through cavity

21

Flow guide surface

22

fin

23

flooded cavity

24

Flow nose

25

Mounting bridge

26

Mounting opening

27

Mounting arm

A

buoyancy body

G

bodies of water

N

Navigation satellites

O

objects or living beings

S

Underwater structures

Claims (14)

A sonar measuring device for detecting underwater structures, comprising a sonar sensor (5) and a radio-controlled aircraft (1), wherein the radio-controlled aircraft (1) has a platform (2) and the sonar sensor (5) is connected to the platform (2), and wherein an elongate flexible connecting element (6) comprising an electrical cable connection (7) is connected at its first end to the platform (2) of the radio-controlled aircraft (1) and at its opposite end to a submersible body (8), and the sonar sensor (5) is attached to the submersible body (8), wherein the sonar sensor (5) is connected to the radio-controlled aircraft (1) via the electrical cable connection (7), characterized in that the sonar measuring device comprises a ground receiving unit (11) with an antenna (12), a satellite navigation receiver (13) for detecting a stationary reference position, and a ground receiving unit (11) connected to the antenna (12) and the satellite navigation receiver (13). coupled measuring unit (14), wherein the ground receiving unit (11) is designed for radio reception of the sonar data currently measured with the sonar sensor (5) when immersed in a body of water (G) to be examined, for georeferencing this sonar data with the stationary reference position and the current position of the radio-controlled aircraft (1) and for photorealistic representation of the currently received and georeferenced sonar data on a screen. Sonar measuring device according to Claim 1 , characterized in that the radio-controlled aircraft (1) has a position and/or attitude sensor and is set up for automatic real-time detection of the current position of the radio-controlled aircraft (1) from the position and/or attitude currently measured with the position and/or attitude sensor with reference to the stationary reference position. Sonar measuring device according to Claim 1 or 2 , characterized in that the ground receiving unit (11) has a radio base station (11) and the radio-controlled aircraft (1) has a radio communication unit (15), wherein the radio communication unit (15) and the radio base station (16) are set up for bidirectional radio communication in order to send control commands from the measuring unit (14) to the radio-controlled aircraft (1) and to send measured sensor data as well as position and/or attitude data of the radio-controlled aircraft (1) from the radio-controlled aircraft (1) to the ground receiving unit (11). Sonar measuring device according to one of the Claims 1 until 3 , characterized in that the radio-controlled aircraft (1) is a rotary-wing aircraft having a number of rotors (3) on the upper side of the platform (2) and a loading structure (4) on the underside of the platform (2). Sonar measuring device according to Claim 4 , characterized in that the rotorcraft (1) has lifting bodies (A) on its landing structure (4). Sonar measuring device according to one of the preceding claims, characterized in that the sonar measuring device for controlling the radio-controlled aircraft (1) is set up in such a way that sonar measurements are carried out in towed flight. Sonar measuring device according to one of the preceding claims, characterized in that the immersion body (8) has a rod-shaped weight element, such as a hollow tube. Sonar measuring device according to Claim 7 , characterized in that the sonar sensor (5) is arranged at a distance from the submersible body (8) and is attached to the immersion body (8) with at least one web (9). Sonar measuring device according to Claim 8 , characterized in that the web (9) is a fin (22). Sonar measuring device according to one of the Claims 7 until 9 , characterized in that the rod-shaped weight element has a first front end and a diametrically opposite second front end, wherein the elongated flexible connecting element (6) is fastened to the first front end of the rod-shaped weight element and a flow guide element (10) is arranged at the diametrically opposite second front end. Sonar measuring device according to one of the preceding claims, characterized in that the immersion body (8) has at least one flow guide element (10). Sonar measuring device according to Claim 11 , characterized in that at the bow region of the submersible body (8), to which the elongated flexible connecting element (6) is attached, two flow guide surfaces (21) protrude from the submersible body (8) on both sides, pointing diametrically away from each other, transversely to the direction of the spacing of the sonar sensor (5) from the submersible body (8). Sonar measuring device according to one of the preceding claims, characterized in that in the fastening area of the sonar sensor (5) between the sonar sensor (5) and the immersion body (8) there is arranged a cavity (23) which is open to the outside and can be flooded with water. Sonar measuring device according to one of the preceding claims, characterized in that the immersion body (8) has a fastening web (26) with fastening openings (27) arranged at a distance from one another in the longitudinal direction of the immersion body (8) for fastening the elongate flexible connecting element (6) to the immersion body (8).