Autonomous unmanned underwater vehicle and intermediate segment

Abstract

An autonomous, unmanned underwater vehicle (1) with a hull section (2) and a head section (3) is described, wherein a sensor (4) is arranged on the head section (3). An intermediate segment (5) is provided, which has a first connecting piece (6) designed for attachment to the hull section (2), a second connecting piece (7) designed for attachment to the head section (3), and a stepper motor (10). The first and second connecting pieces (6, 7) are mounted so as to be rotatable relative to one another about the longitudinal axis (L) of the underwater vehicle (1). The stepper motor (10) is mounted with the first and second connecting pieces (6, 7) for the controlled rotation of the head section (3) with its sensor (4) by rotational angle increments predetermined by the stepper motor (10).

Description

[0001] The invention relates to an autonomous unmanned underwater vehicle having a hull part and a head part, wherein a sensor is arranged on the head part.

[0002] The invention further relates to an intermediate segment for an autonomous unmanned underwater vehicle.

[0003] EP 2 830 934 B1 discloses an autonomous underwater vehicle with a hull part and a head part as well as sensors permanently installed in the head part.

[0004] DE 10 2012 107 727 B4 discloses a distance determination method that can be used as part of a distance control method for a method for inspecting a flooded tunnel, in particular a pipeline or a drinking water tunnel, using an autonomous underwater vehicle. Distances between the underwater vehicle and a tunnel body surrounding the underwater vehicle around its longitudinal axis are determined optically in different directions using a laser and a camera by means of laser triangulation.

[0005] Jan Albiez, Alexander Duda, Martin Fritsche, Felix Rehrmann, Frank Kirchner: "CSurvey - An autonomous optical inspection head for AUVs," in: Robotics and Autonomous Systems, Vol. 67, May 2015, pages 72 to 79, discloses an autonomous underwater vehicle with a hull section and a head section rigidly attached to it. The head section has a manipulator with a sensor, such as a camera, mounted on the manipulator. The sensor's position can be adjusted by the manipulator.

[0006] The object of the present invention is to provide an improved autonomous underwater vehicle in which the sensor in the head section can be rotated with high precision by defined angular increments relative to the hull section using control signals, even under environmental influences, and is thereby stably mounted.

[0007] The object is achieved by the autonomous underwater vehicle having the features of claim 1 and by the intermediate segment having the features of claim 8. Advantageous embodiments are described in the subclaims.

[0008] It is proposed that the autonomous underwater vehicle have an intermediate segment comprising a first connecting piece configured for attachment to the hull section and a second connecting piece configured for attachment to the head section, as well as a stepper motor. The first and second connecting pieces are mounted for rotation relative to one another about the longitudinal axis of the underwater vehicle. The stepper motor is mounted with the first and second connecting pieces for controlled rotation of the head section with its sensor by rotation angle increments predetermined by the stepper motor.

[0009] This ensures that the head section is stable in position yet can be rotated precisely around its axis of rotation. The rotatable attachment of the sensor head section to the hull section, with the intermediate segment mountable between them, results in low-vibration and very stable mounting. The intermediate piece, designed with the stepper motor as the drive element, can be used as needed if a change in the position of the sensor, which is permanently mounted on the head section, is desired. Otherwise, the underwater vehicle can also be used without the intermediate segment according to the invention.

[0010] The intermediate segment for an autonomous unmanned underwater vehicle, which can be optionally installed as an additional component between the hull section and the head section, comprises a first connecting piece with a connecting flange designed for attachment to the hull section, a second connecting piece with a connecting flange designed for attachment to the head section, and a stepper motor. The first and second connecting pieces are mounted for rotation relative to one another around the longitudinal axis of the underwater vehicle. The stepper motor is mounted with the first and second connecting pieces for controlled rotation of the head section with its sensor by rotation angle increments specified by the stepper motor.

[0011] Sensors directed towards the bottom of the water cannot fully examine structures in the water next to the underwater vehicle. To examine laterally located structures with downward-facing sensors, the underwater vehicle would have to travel directly on the water surface, which makes the measurements extremely susceptible to blurring caused by waves. In addition, the aperture angle of the sensors would have to be greatly widened, which would reduce the resolution of the data sets. The upper area of ​​the structure to be examined cannot be recorded in this way. An additional examination of structures above the underwater vehicle in the water with sensors fixed to the hull is only possible if an additional sensor is mounted that is specifically aimed at this upper area.

[0012] With the help of the intermediate segment, complete, high-resolution data sets of structures beside and above the underwater vehicle can now be acquired using sensors that can be rotated around the rotation axis. This enables the highly important safety-oriented observation of maritime infrastructure. This allows for the investigation of long structures such as sheet pile walls or ship hulls.

[0013] The pivoting mounting of the head section on the fuselage section with the aid of the intermediate segment enables the integration of even relatively large and heavy sensors, such as multibeam echo sounders suitable for inspection. The intermediate segment with its stepper motor prevents uncontrollable drift between the actual orientation of the sensor and the software control. The use of an intermediate segment also achieves a high degree of modularity. Different head sections with their sensors, which are provided in a set for selection and installation on a fuselage section, can now be converted to a rotatable function using the uniform intermediate segment. This eliminates the need for separate individual actuators in the head sections to change the position of the sensors.

[0014] Due to its modularity, the intermediate segment can expand the application possibilities of both existing and new sensor heads, but can also be quickly dismantled if no longer required.

[0015] The use of a stepper motor with additional detection and feedback of the actual position improves the evaluation of the data acquired by the sensors in the sensor head, taking into account their actual orientation, as well as the usability of the rotatable intermediate segment even over long autonomous missions without drift.

[0016] Commercially available stepper motors with an integrated control unit can be used for the rotational movement, which preferably form a closed, waterproof and pressure-resistant unit and can be designed for different depths depending on the area of ​​application.

[0017] The stepper motor can, for example, be controlled directly by a processing unit of the autonomous underwater vehicle via a serial interface or by a freely programmable microcontroller board in a waterproof pressure hull. The latter allows the use of existing, proprietary hardware and software to control the autonomous underwater vehicle without a freely programmable serial interface. This allows the viewing angle to be changed as often as required during an autonomous underwater vehicle mission. Programming can include rotations at specific times after the start of the mission or upon reaching a specific position in the global coordinate system, although this requires the availability of position data.

[0018] The intermediate segment may have a water-resistant ball bearing for rotatable support, which is immersed in the submerged state of the underwater vehicle.

[0019] Except for the stepper motor and an optional pressure hull for the control unit, the intermediate segment can be open to the outside and flooded when submerged. The moving and stationary parts can be guided to each other via seawater-resistant ball bearings, for example, made of plastic or glass. The ball bearings are also flooded. This avoids larger sealing surfaces and eliminates the need for pressure testing of the entire intermediate segment, simplifying modular use and assembly and disassembly in the field.

[0020] For this purpose, the stepper motor is preferably enclosed in a pressurized water-resistant housing. The interior of the intermediate segment surrounding the stepper motor can be open to the outside and flooded when the underwater vehicle is submerged.

[0021] The intermediate segment may have buoyancy elements, such as buoyancy foam. The buoyancy element may have cable entry openings.

[0022] The intermediate segment is kept weight-neutral in the water through the use of buoyancy foam. The buoyancy foam can be designed to also serve as a guide for the cables connecting the sensors to the main pressure hull of the autonomous underwater vehicle, preventing tangling when the head rotates. Sufficient space is provided for the cables in both the radial and axial directions inside the intermediate segment to allow for the intended rotation angles.

[0023] The first connecting piece of the intermediate segment may have a connecting flange with fastening elements which correspond to a connecting flange of the fuselage part for fastening the head part to the fuselage part.

[0024] The first connecting piece can be arranged rotatably around the second connecting piece of the intermediate segment which is fixedly attached to the fuselage part, wherein the stepper motor has a stator and a rotor and the stator of the stepper motor is coupled to the second connecting piece and the rotor is coupled to the first connecting piece.

[0025] The rotatable connecting flange of the intermediate segment on the sensor head section side is designed so that the sensor head section can be mechanically attached to it in the same way as it would be mechanically attached to the main pressure hull of the autonomous underwater vehicle, i.e., the hull section, without an intermediate segment. The connecting flange can be provided with feedthroughs and mounting options for adapter sockets, allowing the intermediate segment to be equipped with extension cables, so that the head section can be wired regardless of whether an intermediate segment is used.

[0026] In general, in the context of this application, the words "a / an," unless expressly defined otherwise, are not to be understood as numerals, but as indefinite articles with the literal meaning "at least one / an." Angles are given as degrees with a full angle of 360°, where 1° (degree) corresponds to the radian 180° / π rad.

[0027] The invention is described in more detail below using an exemplary embodiment.

[0028] They show: Fig. 1 - Side section view of an autonomous underwater vehicle with intermediate segment between head section and hull section; Fig. 2 - Lateral section view of the intermediate segment.

[0029] Fig. 1 shows a side sectional view of an autonomous underwater vehicle 1 with a hull part 2 and a head part 3.

[0030] The head part has at least one sensor 4. Sensor 4 can be, for example, an optical camera, a laser distance measuring device, such as a LiDAR sensor, an ultrasonic sensor (echo sounder), and the like, mounted on the head part 3 or built into the head part 3. The head part 3 thus provides a sensor head.

[0031] An intermediate segment 5, which can be retrofitted if required, is arranged between the fuselage section 2 and the head section 3. The intermediate segment has a first connecting piece 6 for attachment to the front side of the fuselage section 2 and a second connecting piece 7 for attachment to the opposite front side of the head section 3.

[0032] The fuselage part 2 and the head part 3 have complementary connecting flanges which are designed for the detachable fastening of the head part 3 to the front, i.e. bow-side, end face of the fuselage part 2.

[0033] The intermediate segment 5 can have a first and second connection flange on each of the first and second connection pieces 6, 7. The first connection piece 6 is designed to complement a fuselage connection flange 8 of the fuselage part 2 in order to releasably fasten the bow-facing end face of the rump 3 to the fuselage connection flange 8, for example with fastening bolts or fastening screws. The second connection piece 7 is designed to complement a sensor head connection flange 9 of the head part 3 in order to releasably fasten the stern-facing end face of the head part 3 to the sensor head connection flange 9, for example with fastening bolts or fastening screws.

[0034] The intermediate segment 5 has a stepper motor 10, which has a stationary stator 11 and a rotor 12 rotatable about a rotation axis R. The stator 11 is connected in a rotationally fixed manner to the second connecting piece 7. Thus, when the intermediate segment 5 is installed, the stepper motor 10 is connected in a rotationally fixed manner to the body part 2. The stator 11 is connected in a rotationally fixed manner to the first connecting piece 6 and, when installed, is coupled in a rotationally fixed manner to the head part 3.

[0035] With the help of the stepper motor 10, a rotation can be performed precisely by the specified number of rotation angles according to the design-specified rotation angle increments of the stepper motor 10. The rotational position of the head section 3 about the rotation axis R is thus always precisely specified, largely unaffected by external interference, and known.

[0036] The rotation axis R of the stepper motor 10 is preferably located in the longitudinal axis L of the underwater vehicle 1.

[0037] For stable mounting of the rotor 12, which can rotate about the rotation axis R with the head section 3 attached thereto, a ball bearing 13 is provided, which circumferentially surrounds the rotation axis R. The ball bearing 13 can be arranged between the second connecting piece 7 and an intermediate segment housing 14 or the stator 11. The ball bearing 13 is preferably made of seawater-resistant material, e.g., ceramic, glass, or stainless steel. It can be designed to be unsealed and thus immersed in the submerged state of the underwater vehicle 1.

[0038] The stepper motor 10, however, is preferably housed in a pressurized water-resistant housing. A control unit 15 for the stepper motor 10 can be arranged together with the stepper motor 10 adjacent to the mechanical parts of the stepper motor 10 and also housed in a pressurized water-resistant housing.

[0039] A gap 16 surrounding the stepper motor 10 can be open to the outside so that, when submerged, water flows into the gap 16 and floods it. This has the advantage of counteracting a change in the weight proportions and buoyancy behavior of the underwater vehicle 1 compared to the direct connection of the head section 3 to the hull section 2 without an intermediate segment 5 when the intermediate segment 5, which can be optionally retrofitted for the controlled alignment of the sensor 4, is mounted between the head section 3 and the hull section 2.

[0040] Furthermore, at least one buoyancy body 17 can be arranged in the intermediate space 16 of the intermediate segment 5. This can provide additional weight compensation, which brings the weight proportions in the submerged state closer to the weight proportions of the underwater vehicle 1 without the intermediate segment 5. The buoyancy body 17 can be formed, for example, from a buoyancy foam.

[0041] The buoyancy bodies 17 can have at least one cable duct 18 through which electrical cables are routed, leading from the rotatable head section 3 to the fuselage section 2. This allows the electrical cables to rotate when the head section 3 rotates while being securely mounted. Excessive twisting of the electrical cables can be prevented by restricting the angle of rotation of the head section 3. For example, it can be limited to a total angle of 360° or 180° in both directions starting from a zero position. However, a more extensive limitation is also conceivable, for example to 270° ±30° or 135° ±15° per direction of rotation. The maximum angles of rotation achievable from the basic position in both directions of rotation are the same with this symmetrical design.

[0042] A design with a rotation initiated by the stepper motor 10 is also conceivable, covering a range from -90° to approximately +230°, with the rotation angle of 0° being the basic position with the sensors 4 pointing downwards. The maximum rotation angles achievable from the basic position in both directions of rotation are different from one another in this asymmetrical design.

[0043] The hull section 2 has a drive unit 19, for example with a propeller drive, and a steering and stabilization unit 20 with fins and movable guide surfaces for the controlled movement of the underwater vehicle 1. It can also have a communication unit 21, which is functionally connected to the control unit 15 as well as the drive unit 19 and the steering and stabilization unit 20, in order to receive control signals from a control center 22 for controlling the position and attitude of the underwater vehicle 1 and the rotational angle orientation of the head section 3 with its at least one sensor 4. The sensor data acquired by the at least one sensor 4 can, if necessary, be transmitted to the control center 22 during the diving process. This achieves feedback from the environment of the underwater vehicle 1, through which an interactive control of the underwater vehicle 1 into the desired position and control of the sensor 4 into the desired attitude can take place.

[0044] Fig. Figure 2 shows a side sectional view of the intermediate segment 5. It is clear that the intermediate segment 5 is designed as an element that can be mounted as needed between the head section 3 and the body section 2. The first connecting piece 6 is arranged so as to be rotatable about the rotation axis R relative to the second connecting piece 7. For this purpose, the stepper motor 10 is coupled between the first and second connecting pieces 6, 7. The stepper motor 10 is controlled via a pressurized water-resistant control unit 15 integrated into the stepper motor 10 or via a cable connection by an external control unit 15. The direction of rotation and the number of rotation angle increments are specified by a control signal, so that the rotational position of the stator 11 and rotor 12 of the stepper motor 10 is always precisely predefined and known.

[0045] A stable pivot bearing, which also withstands mechanical environmental influences such as wave action and the impact of objects and fish, is achieved by a ball bearing 13 in the rotary connection between the first and second connecting pieces 6, 7. Thus, the at least one sensor 4 is mounted on the head part 3, which is rotatable relative to the body part 2 by the intermediate segment 5, in a low-vibration and stable manner, yet still adjustable in position on the body part 2.

[0046] It can be seen that the intermediate segment 5 has buoyancy bodies 17 surrounding the stepper motor 10. To guide the electrical cables running from the at least one sensor 4 in the head section 3 to the fuselage section 2, at least one cable duct 18 is provided in the buoyancy body 17. This predetermines the position of the cables, even if they twist relative to the stationary fuselage section 2 during rotation of the head section 3 about the rotation axis R. This prevents jamming of the cables or an uncontrolled position of the cables. List of reference symbols 1 Autonomous underwater vehicle 2 fuselage section 3 headboard 4 Sensor 5 Intermediate segment 6 first connecting piece for fuselage section 7 second connection piece for headboard 8 Fuselage connection flange 9 Sensor head connection flange 10 Stepper motor 11 Stator 12 Rotor 13 ball bearings 14 Intermediate segment housing 15 Control unit 16 space 17 buoyancy bodies 18 Cable entry 19 Drive unit 20 Steering and stabilization unit 21 Communication unit 22 Control center L Longitudinal axis R rotation axis QUOTES CONTAINED IN THE DESCRIPTION

[0000] This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions. Cited patent literature

[0000] EP 2 830 934 B1

[0003] DE 10 2012 107 727 B4

[0004] Cited non-patent literature

[0000] Jan Albiez, Alexander Duda, Martin Fritsche, Felix Rehrmann, Frank Kirchner: “CSurvey—An autonomous optical inspection head for AUVs,” in: Robotics and Autonomous Systems, Vol. 67, May 2015, pages 72 to 79

[0005]

Claims

[1] Autonomous unmanned underwater vehicle (1) with a hull part (2) and a head part (3), wherein a sensor (4) is arranged on the head part (3), characterized by an intermediate segment (5) which has a first connecting piece (6) designed for attachment to the hull part (2) and a second connecting piece (7) designed for attachment to the head part (3) and a stepper motor (10), wherein the first and second connecting pieces (6, 7) are mounted so as to be rotatable relative to one another about the longitudinal axis (L) of the underwater vehicle (1) and the stepper motor (10) is mounted with the first and second connecting pieces (6, 7) for the controlled rotation of the head part (3) with its sensor (4) by rotation angle increments predetermined by the stepper motor (10). [2] Autonomous unmanned underwater vehicle (1) according to claim 1, characterized bythat the intermediate segment (5) has water-resistant ball bearings (13) for rotatable mounting, which are surrounded by water when the underwater vehicle (1) is submerged. [3] Autonomous unmanned underwater vehicle (1) according to claim 1 or 2, characterized by that the stepper motor (10) is housed in a pressurized water-tight manner and the interior of the intermediate segment (5) surrounding the stepper motor (10) is open to the outside and flooded when the underwater vehicle (1) is submerged. [4] Autonomous unmanned underwater vehicle (1) according to one of claims 1 to 3, characterized by that the intermediate segment (5) has buoyancy bodies (17), for example a buoyancy foam. [5] Autonomous unmanned underwater vehicle (1) according to claim 4, characterized by that the buoyancy body (17) has cable ducts (18). [6] Autonomous unmanned underwater vehicle (1) according to claim 1, characterized bythat the first connecting piece (6) of the intermediate segment is a connecting flange with fastening elements which correspond to a fuselage connecting flange (8) of the fuselage part (2) for fastening the head part (3) to the fuselage part (2). [7] Autonomous unmanned underwater vehicle (1) according to one of the preceding claims, characterized by that the first connecting piece (6) is rotatable about the second connecting piece (7) of the intermediate segment (5) which is fixedly attached to the fuselage part (2), wherein the stepper motor (10) has a stator (11) and a rotor (12) and the stator (11) of the stepper motor (10) is coupled to the second connecting piece (7) and the rotor (12) is coupled to the first connecting piece (6). [8] Intermediate segment (5) for an autonomous unmanned underwater vehicle according to one of the preceding claims, characterized byin that the intermediate segment (5) has a first connecting piece (6) with a connecting flange designed for attachment to the body part (2) and a second connecting piece (7) with a connecting flange designed for attachment to the head part (3) and a stepper motor (10), wherein the first and second connecting pieces (6, 7) are mounted so as to be rotatable relative to one another about the axis of rotation (R) of the intermediate segment (5) and the stepper motor (10) is mounted with the first and second connecting pieces (6, 7) for the controlled rotation of the head part (3) with its sensor (4) by rotation angle increments predetermined by the stepper motor (10). [9] Intermediate segment (5) according to claim 8, characterized by that the intermediate segment (5) has water-resistant ball bearings (13) for rotatably supporting the first and second connecting pieces (6, 7) relative to one another about the rotation axis (R) of the stepping motor (10). [10] Intermediate segment (5) according to claim 8 or 9, characterized by that the stepper motor (10) is housed in a pressure-water-resistant manner and the interior of the intermediate segment (5) surrounding the stepper motor (10) is open to the outside for flow. [11] Intermediate segment (5) according to one of claims 8 to 10, characterized by that the intermediate segment (5) has a buoyancy body (17), for example a buoyancy foam. [12] Intermediate segment (5) according to claim 11, characterized by that the buoyancy body (17) has cable feedthrough openings (18). [13] Intermediate segment (5) according to one of claims 8 to 12, characterized by that the first connecting piece (6) of the intermediate segment (5) is a connecting flange with fastening elements which correspond to a fuselage connecting flange (8) of the fuselage part (2) for fastening the head part (3) to the fuselage part (2). [14] Intermediate segment (5) according to one of claims 8 to 13, characterized bythat the second connecting piece (7) is rotatable about the second connecting piece (6) of the intermediate segment (5), which can be fixedly attached to the fuselage part (5), wherein the stepper motor (10) has a stator (11) and a rotor (12) and the stator (11) of the stepper motor (10) is coupled to the first connecting piece (6) and the rotor (12) is coupled to the second connecting piece (7).

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