Two axis four rudder small unmanned ship

Abstract

To provide a two shaft four rudder small-sized unmanned ship capable of easily performing direction control and speed control and excellent in ship maneuvering performance.SOLUTION: A ship maneuvering system 100 includes a ship maneuvering control device 201 that controls directions of propeller slipstreams of a propulsion propeller 104a and a propulsion propeller 105b by changing a combination of rudder angles of a high-lift rudder 101a and a high-lift rudder 101b to control an acting direction of a thrust around a stem acting on a ship body, a ship maneuvering instruction unit 202 that instructs the ship maneuvering control device 201 on a direction of a ship body motion, and a remote control device 203 that instructs the ship maneuvering instruction unit 202 on the direction of the ship body motion via wireless communication. The ship handling control device 203 has a low-speed pivot turning function unit 206 that performs a pivot turning ship handling by setting the pair of high-lift rudders 101a and 101b corresponding to one pusher propeller 101a at a backward rudder angle and setting the pair of high-lift rudders 101b and 104b corresponding to the other pusher propeller 105a at a forward rudder angle in a state where the left and right pusher propellers and 105b rotate constantly at a low speed in the forward direction in a low-speed area ship handling. 104a.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a small unmanned vessel with two propellers and four rudders, and relates to a ship-handling technique that allows for easy direction control and speed control. [Background technology]

[0002] For example, Patent Document 1 describes a floating body on water that has improved safety when it is navigated autonomously or remotely. This floating body is equipped with an operation unit for steering the floating body on water, a navigation unit that generates propulsion force and navigates the floating body in a desired direction, a communication unit that communicates with an operation terminal, and a control unit that controls the navigation unit so that the floating body navigates autonomously. When an operation signal from either the operation unit or the operation terminal is detected during autonomous navigation, the control unit stops the autonomous navigation and controls the navigation unit based on the operation signal with the highest priority from the operation signals from the operation unit and the operation terminal. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent Publication No. 2023-117311 Summary of the Invention [Problem to be solved by the invention]

[0004] Conventional unmanned watercraft include those that navigate autonomously using a program, those that are manually controlled based on camera footage via radio, and those that are remotely controlled via satellite.

[0005] Some of the areas in which these unmanned surface vessels are expected to be used include the following: 1. Long-term observation of offshore meteorological and oceanographic conditions associated with the construction of offshore wind power plants, collection of data such as seabed conditions, biological and ecological measurements, etc. will be carried out continuously over long periods of time using remote control or unmanned autonomous driving functions. 2. In the fisheries industry, patrol monitoring of live fish farms, aquaculture management such as feeding, etc. will be carried out using remote control or autonomous navigation functions for unmanned automatic navigation. 3. In maritime logistics operations, regular operations can be carried out safely even in bad weather through remote control or unmanned automatic navigation functions. 4. Using remote control and unmanned automated navigation functions, we will continue to collect oil and garbage, which are the causes of marine pollution, and monitor the marine ecosystem for long periods of time. 5. In maritime surveillance operations aimed at maintaining public order, fleeing vessels will be stopped, and convoys of ships will be prevented from illegally entering territorial waters, and the pursuit of such vessels will be carried out safely using remote control and unmanned autonomous navigation functions.

[0006] However, many unmanned surface vessels have relatively small hulls, do not have large main engine outputs, do not have strong propeller wakes, and have small rudders.

[0007] Such unmanned surface vessels generally have poor steering effectiveness at low speeds, often have problems with directional control, and do not have high course-keeping capabilities.

[0008] The present invention aims to solve the above-mentioned problems and to provide a small unmanned vessel with two shafts and four rudders that has excellent maneuverability and can easily control direction and speed. [Means for solving the problem]

[0009] In order to solve the above problems, the twin-shaft, four-rudder small unmanned vessel of the present invention comprises a thrust system, a maneuvering system that controls the thrust system, and an observation system that observes the hull motion state of the vessel itself, the observation system comprising a position measuring device that measures the vessel's position and a monitoring device that monitors the vessel's surroundings, the thrust system comprising a pair of propeller shafts that rotate in opposite directions, a pair of left and right propellers with opposite blade angles that are mounted on each propeller shaft and located at the stern, a pair of left and right high-lift rudders that are located behind each propeller, electric steering gears that drive each high-lift rudders, and a rudder angle control device that controls the rudder angle of each high-lift rudders, the maneuvering system controls the electric steering gears of each high-lift rudders via the rudder angle control device, and while the left and right propellers are rotating at a constant speed in the forward direction, each steering gear operates each high-lift rudders independently to various angles, and a combination of rudder angles of the pair of high-lift rudders corresponding to each propeller is controlled. a maneuvering control device that controls the direction of the propeller wake of each propeller by changing the position of the propellers, thereby controlling the direction of thrust around the stern acting on the hull; a maneuvering instruction unit that instructs the maneuvering control device on the direction of hull movement using an autonomous navigation program or remote maneuvering; and a remote control device that instructs the maneuvering instruction unit on the direction of hull movement via wireless communication, the remote control device having a monitor screen that displays the position information of the ship and a monitor screen that displays information about the surroundings of the ship, a joystick operation unit for manual maneuvering, and a low-speed maneuvering switch button for switching the maneuvering control device to low-speed maneuvering, and the maneuvering control device has a low-speed on-the-spot turning function unit that performs on-the-spot turning maneuver by setting a pair of high-lift rudders corresponding to one of the propellers to a reverse rudder angle and a pair of high-lift rudders corresponding to the other propeller to a forward rudder angle when the left and right propellers are rotating at a constant low speed in the forward direction during low-speed maneuvering.

[0010] In the small unmanned ship with two shafts and four rudder of the present invention, the maneuvering control device is characterized by having a turning speed adjustment function unit that, during low-speed maneuvering, when the left and right propulsion propellers are rotating at a constant low speed in the forward direction, controls the pair of high-lift rudders corresponding to one of the propulsion propellers to increase or decrease the rudder angle within a reverse steering angle range while maintaining a symmetrical rudder angle, and controls the pair of high-lift rudders corresponding to the other propulsion propeller to increase or decrease the rudder angle within a forward steering angle range while maintaining a symmetrical rudder angle, thereby controlling the moment around the stern acting on the hull and adjusting the turning speed during low-speed maneuvering. [Effects of the Invention]

[0011] With the above configuration, in the small unmanned two-screw, four-rudder vessel of the present invention, by changing the combination of rudder angles of a pair of high-lift rudders corresponding to each propeller, the propeller wakes generated from each propeller can be reliably controlled independently by the pair of high-lift rudders, and the direction of thrust acting on the hull around the stern can be controlled, thereby achieving stable maneuverability.

[0012] In other words, with the small, two-shaft, four-rudder unmanned rudder of the present invention, when maneuvering at low speeds, with the left and right propellers rotating at a constant low speed in the forward direction, by setting a pair of high-lift rudders corresponding to one of the propellers to a reverse rudder angle, a reverse thrust acts on one side of the stern, and by setting a pair of high-lift rudders corresponding to the other propeller to a forward rudder angle, a forward thrust acts on the other side of the stern, so that on-the-spot turning maneuvering can be achieved at low speeds without the need to reverse the rotation of the main engine or increase its power output.

[0013] Furthermore, in the small unmanned twin-screw, four-rudder vessel of the present invention, when maneuvering at low speeds, with the left and right propellers rotating at a constant low speed in the forward direction, the magnitude of the astern thrust acting on one side of the stern can be adjusted by controlling the rudder angle of the pair of high-lift rudders corresponding to one of the propellers within the astern steering angle range, and the forward thrust acting on the other side of the stern can be adjusted by controlling the rudder angle of the pair of high-lift rudders corresponding to the other propeller within the forward steering angle range.This allows the turning speed during maneuvering at low speeds to be adjusted by controlling the moment around the stern acting on the hull without the need to reverse the main engine or increase its output, thereby achieving maneuvering performance that makes it easy to control the direction of the bow and the speed of turning. [Brief explanation of the drawings]

[0014] [Figure 1] Schematic diagram showing a two-propeller, four-rudder small unmanned vessel according to an embodiment of the present invention. [Figure 2] FIG. 2 is a block diagram showing a small unmanned vessel with two shafts and four rudders according to the embodiment. [Figure 3] FIG. 2 is a block diagram showing the configuration of the ship steering control device according to the embodiment; [Figure 4] FIG. 2 is a block diagram showing the configuration of a remote control device according to the embodiment; [Figure 5] FIG. 4 is a schematic diagram showing the operating range of the high-lift rudder in the embodiment. [Figure 6] 5A and 5B are schematic diagrams showing the combined rudder angle and propulsion direction of the high-lift rudder in (a) forward, (b) hover, and (c) reverse maneuvers in the embodiment; [Figure 7] Schematic diagrams showing the combined rudder angles and propulsion directions of the high-lift rudder in each of the following maneuvers: (d) forward left turn, (e) forward left turn, (f) reverse left pull, and (g) reverse left turn in the same embodiment. [Figure 8] Schematic diagrams showing the combined rudder angles and propulsion directions of the high-lift rudder in each of the following maneuvers: (h) forward right turn, (i) forward right turn, (j) reverse right pull, and (k) reverse right turn in the same embodiment. [Figure 9] 5 is a schematic diagram showing the combined rudder angle and propulsion direction of the high-lift rudder in each of (n) spot starboard turning and (m) spot port turning in low-speed maneuvers in the embodiment; DETAILED DESCRIPTION OF THE INVENTION

[0015] 1 to 4, a small unmanned ship with two shafts and four rudders according to the present invention includes a thrust system 100, a maneuvering system 200 that controls the thrust system 100, an observation system 300 that observes the hull motion state of the ship 1, a power supply unit 400 that supplies power to the thrust system 100 and the maneuvering system 200, a mission unit 500 configured for various uses, and a mission storage unit 600 that stores the mission unit 500 interchangeably.

[0016] The power supply unit 400 consists of a storage battery 401 and a solar panel 402, and the solar panel 402 is installed on a deck-like structure at the bow and stern of the ship. The mission unit 500 is made up of modules configured for various purposes, and is equipped with inspection equipment, sensors, manipulators, and other operating devices required for each mission, such as observing offshore weather and sea conditions, observing the state of the seabed, collecting data such as biological and ecological measurements, patrolling and monitoring live aquaculture, spreading feed, recovering oil or garbage that causes marine pollution, and monitoring the marine ecosystem. The mission storage unit 600 is an area separated from the other parts by a bulkhead and holds the mission units in a replaceable manner.

[0017] The observation system 300 has position measurement devices for measuring the position of the ship 1, here consisting of a ship radar device 301, a GPS compass (a gyrocompass is also possible) 302, and a transmitting / receiving antenna device 303, and has, as monitoring devices for monitoring the area around the ship 1, a ship surroundings monitoring camera 304 consisting of a normal camera, and an infrared monitoring camera 305 which is effective for monitoring at night.

[0018] The thrust system 100 has two propulsion propellers 101a and 101b arranged at the stern, electric motors 102a and 102b that drive the propulsion propellers 101a and 101b, and thrust control devices 103a and 103b that control the rotation speed of the propulsion propellers 101a and 101b. The vessel has pairs of high-lift rudders 104a, 104b, 105a, 105b, four electric steering gears 106a, 106b, 107a, 107b that drive each of the high-lift rudders 104a, 104b, 105a, 105b, and rudder angle control devices 108a, 108b, 109a, 109b that control the rudder angle of each of the high-lift rudders 104a, 104b, 105a, 105b.

[0019] As shown in Figure 5, the high-lift rudders 104a, 104b, 105a, and 105b are rudders having rudder blades whose cross-sectional shape along the axial direction of the propulsion propellers 101a and 101b has a high-lift cross-sectional profile. There are various shapes of high-lift rudder blades, but the rudder blades of the high-lift rudders 104a, 104b, 105a, and 105b of this embodiment have the following shape: That is, in the horizontal cross-sectional profile, they have a shape consisting of a leading edge portion that protrudes forward in a semicircular shape, a middle portion that increases in width in a streamlined manner from the leading edge portion and then gradually decreases in width toward the minimum width portion, and a fishtail trailing edge portion that continues from the middle portion and gradually increases in width toward the aft end of a predetermined width.

[0020] Each of the high-lift rudders 104a, 104b, 105a, and 105b is configured to be able to steer 105° outboard (outside, toward the ship's port side) and 35° inboard (inner side). By operating the pair of high-lift rudders 104a, 104b on the starboard side or the pair of high-lift rudders 105a, 105b on the port side independently at various angles while keeping both propulsion propellers 101a, 101b rotating in the forward direction and changing the combination of the rudder angles of the pair of high-lift rudders 104a, 104b, 105a, 105b on both sides, it is possible to distribute the propeller wake in a desired direction and freely change the thrust in each direction.

[0021] Therefore, by controlling the propeller wakes of the propellers 101a and 101b on both sides and controlling the thrust around the stern in all directions (360°), the ship can be steered forward and backward, stopped, turned forward, turned backward, etc., and the ship's movement can be freely controlled.

[0022] The ship steering system 200 includes a ship steering control device 201 that controls the electric steering gears 106a, 106b, 107a, and 107b of each high-lift rudders 104a, 104b, 105a, and 105b via rudder angle control devices 108a, 108b, 109a, and 109b, and controls the direction of ship motion by combining the rudder angles of the two high-lift rudders 104a, 104b, 105a, and 105b, a ship steering instruction unit 202 that instructs the ship steering control device 201 on the direction of ship motion using an autonomous navigation program or remote ship steering, and a remote control device 203 that instructs the ship steering instruction unit 202 on the direction of ship motion via wireless communication.

[0023] Although the remote control device 203 is shown in FIG. 2 for the sake of convenience, it actually exists separately from the ship 1 and has the configuration shown in FIG.

[0024] The remote control device 203 has a communication device 251, a first monitor screen 252 that displays a GPS compass direction display image, a second monitor screen 253 that displays a radar image, a third monitor screen 254 that displays images from the ship's surroundings monitoring camera 304, a fourth monitor screen 255 that displays images from the infrared monitoring camera 305, a joystick operation unit 256, and a low-speed range maneuvering switch button 257 that switches to maneuvering in the low-speed range.

[0025] The joystick operation unit 256 is configured so that a joystick lever 258 can be operated in either the X or Y direction, and the commanded direction of movement of the hull is controlled by the tilting direction of the joystick lever 258. That is, the rudder angles of the pair of high-lift rudders 104a, 104b, 105a, 105b on both sides are controlled to rudder angles set in accordance with the tilting direction of the joystick lever 258, and by combining the rudder angles of the high-lift rudders 104a, 104b, 105a, 105b on both sides, the thrust of the propeller wake is turned toward the desired direction, and the rudder angles of the pair of high-lift rudders 104a, 104b, 105a, 105b on both sides are controlled by the electric steering gears 106a, 106b, 107a, 107b within a range of 105° outboard and 35° inboard.

[0026] The ship steering control device 201 has a normal ship steering unit 204 and a low speed range ship steering unit 205, and the low speed range ship steering unit 205 has a low speed range on-the-spot turning function unit 206 and a turning speed adjustment function unit 207.

[0027] The ship steering unit 204 normally steers the ship by autopilot using a GPS compass 302, receiving information necessary for navigation such as destination, route, ship speed, etc. from an autonomous navigation program installed in the ship steering instruction unit 202, and automatically steers the ship autonomously while detecting surrounding ships and obstacles with the ship radar device 301. Alternatively, the ship is manually steered by instructing the direction of ship motion from the remote control device 203 to the ship steering instruction unit 202 by wireless communication via the transmitting / receiving antenna device 303.

[0028] During low-speed maneuvering, while the left and right propulsion propellers 101a, 101b are rotating at a constant low speed in the forward direction, the low-speed on-the-spot turning function unit 206 sets a pair of high-lift rudders 104a, 104b (105a, 105b) corresponding to one of the propulsion propellers 101a (101) to a reverse steering angle, and sets a pair of high-lift rudders 105a, 105b (104a, 104b) corresponding to the other propulsion propeller 101b (101a) to a forward steering angle, thereby performing on-the-spot turning maneuvering.

[0029] The turning speed adjustment function unit 207 controls the pair of high-lift rudders 104a, 104b (105a, 105b) corresponding to one of the propulsion propellers 101a (101b) to increase or decrease the rudder angle within the astern steering angle range while maintaining symmetrical rudder angles during low-speed maneuvering, while the left and right propulsion propellers 101a, 101b are rotating at a constant low speed in the forward direction, and controls the pair of high-lift rudders 105a, 105b (104a, 104b) corresponding to the other propulsion propeller 101b (101a) to increase or decrease the rudder angle within the forward steering angle range while maintaining symmetrical rudder angles, thereby controlling the moment around the stern acting on the hull and adjusting the turning speed during low-speed maneuvering.

[0030] The basic rudder angle combinations of the high-lift rudders 104a, 104b, 105a, and 105b, the state of the joystick lever 258, their names, propeller wake streamlines, and movement directions will be explained with reference to FIGS.

[0031] In Figures 6 to 9, the rudders are shown in horizontal cross section, with the rudder angles of each rudder shown to the side or below. Rudder angles are shown as positive (+) to the right and negative (-) to the left, and names for combinations of these rudder angles are listed. The propeller wake is shown with a thin arrow, and the resulting direction of propulsion of the ship is shown with a thick hollow arrow.

[0032] The rudder angles shown below are examples in this embodiment and do not limit the invention. In the following, the pair of high-lift rudders 104a, 104b on both sides and the pair of high-lift rudders 105a, 105b have the same pattern, and the port rudders and starboard rudders described below are the port rudders and starboard rudders of the pair of high-lift rudders 104a, 104b, 105a, 105b on both sides, respectively.

[0033] As shown in Figure 6, (a) "forward" is when the port rudder is 0° and the starboard rudder is 0° for the pair of high-lift rudders 104a, 104b, 105a, 105b on both sides. Similarly, (b) "hover" (the ship is stopped in place) is when the port rudder is -75° and the starboard rudder is +75°, and (c) "astern" is when the port rudder is -105° and the starboard rudder is +105°.

[0034] As shown in Figure 7, (d) "forward left turn" is port rudder -35° and starboard rudder -35°, (e) "forward left turn" is port rudder -70° and starboard rudder -35°, (f) "astern left shift" is port rudder -105° and starboard rudder +45° to +75°, and (g) "astern left turn" is port rudder -105° and starboard rudder +75° to +105°.

[0035] As shown in Figure 8, (h) "forward right turn" is port rudder +35° and starboard rudder +35°, (i) "forward right turn" is port rudder +35° and starboard rudder +70°, (j) "reverse right shift" is port rudder -45° to -75° and starboard rudder +105°, and (k) "reverse right turn" is port rudder -75° to -105° and starboard rudder +105°.

[0036] In this way, a small unmanned twin-screw, four-rudder ship equipped with a pair of high-lift rudders 104a, 104b and 105a, 105b on both sides can reliably control the propeller wakes generated from each propeller 101a, 101b independently with the pair of high-lift rudders 104a, 104b and 105a, 105b by changing the rudder angle combinations of the pair of high-lift rudders 104a, 104b and 105a, 105b on both sides corresponding to each propeller propeller 101a, 101b, and thereby control the direction of thrust acting on the hull around the stern, thereby achieving easy and stable maneuverability for a twin-screw ship.

[0037] In addition, when performing low-speed maneuvering using the remote control device 203 manually, the low-speed maneuvering switch button 257 is pressed to activate the low-speed maneuvering unit 206, which performs maneuvering in the low-speed range, and activation of the low-speed maneuvering unit 206 switches the rudder angle control by the joystick lever 256 to low-speed maneuvering mode.

[0038] The operation of the above configuration will now be described. Normal steering mode The ship maneuvering system 200 instructs the direction of ship motion to the ship maneuvering control device 201 via the ship maneuvering instruction unit 202. The instruction of the direction of ship motion by the ship maneuvering instruction unit 202 may be performed by an autonomous navigation program or by manual maneuvering using a remote control device 203.

[0039] The ship steering control device 201, which has received instructions on the direction of hull movement from the ship steering instruction unit 202, controls the electric steering gears 106a, 106b, 107a, 107b of each high-lift rudders 104a, 104b, 105a, 105b via rudder angle control devices 108a, 108b, 109a, 109b, and controls the direction of hull movement by combining the rudder angles of each high-lift rudders 104a, 104b, 105a, 105b.

[0040] When manually steering the ship using the remote control device 203, the state of the ship 1 is checked on the first monitor screen 252 that displays a GPS compass direction display image, the second monitor screen 253 that displays a radar image, the third monitor screen 254 that displays images from the ship's surroundings monitoring camera 304, and the fourth monitor screen 255 that displays images from the infrared monitoring camera 305, while the direction of hull movement is instructed to the steering instruction unit 202 using the joystick operation unit 256 to perform manual steering.

[0041] In this manual maneuvering, a small unmanned twin-screw, four-rudder ship equipped with a pair of high-lift rudders 104a, 104b and 105a, 105b on both sides can reliably control the propeller wakes generated from each propeller 101a, 101b independently with the pair of high-lift rudders 104a, 104b and 105a, 105b by changing the rudder angle combinations of the pair of high-lift rudders 104a, 104b and 105a, 105b on both sides corresponding to each propeller propeller 101a, 101b, and thereby control the direction of thrust around the stern acting on the hull in all directions of 360°, thereby achieving easy and stable maneuverability for a twin-screw ship.

[0042] In this type of ship maneuvering, there is no need to reverse the thrust of the propellers (reverse propeller rotation), and all ship maneuvering control can be performed with the propulsion propellers 101a and 101b always rotating forward.By adjusting the rudder angles of both rudders, ship speed can be controlled in a stepless and precise manner from the maximum forward speed corresponding to the propeller rotation speed at that time to the maximum reverse speed, without adjusting the rotation speed of the propulsion propellers 101a and 101b. Low speed maneuvering mode When performing low-speed maneuvering while traveling at low speed in a harbor or congested waters with the two-prong, four-rudder small unmanned vessel according to this embodiment, the low-speed range maneuvering unit 205 for maneuvering in the low-speed range is activated by pressing the low-speed range maneuvering switch button 257. Activating the low-speed range maneuvering unit 205 switches the rudder angle control by the joystick lever 258 to low-speed range maneuvering mode.

[0043] In the low-speed maneuvering mode, the turning direction is indicated by tilting the joystick lever 258, and the low-speed on-the-spot turning function unit 206 adjusts the rudder angles of the pair of high-lift rudders 104a, 104b, 105a, 105b on both sides while the left and right propulsion propellers 101a, 101b rotate at a constant speed in the forward direction.

[0044] For example, in the (n) "spot turn to right" maneuver shown in Figure 9, a pair of high-lift rudders 104a, 104b on the starboard side corresponding to one of the starboard propeller propellers 101a are set to a reverse rudder angle, here -105°, +105°, so that a reverse thrust acts on the starboard side of the stern. Then, a pair of high-lift rudders 105a, 105b corresponding to the other port propeller propeller 101b are set to a forward rudder angle, here 0°, 0°, so that a forward thrust acts on the port side of the stern, so that a spot turn to right maneuver can be realized at low speeds without the need to reverse the propeller propellers 101a, 101b or increase their power.

[0045] 9 (m), "spot turn to port" maneuvering is performed by setting the pair of high-lift rudders 104a, 104b on the starboard side corresponding to one of the starboard propeller propellers 101a to a forward rudder angle, here 0°, 0°, so that forward thrust acts on the starboard side of the stern.Then, by setting the pair of high-lift rudders 105a, 105b corresponding to the other port propeller propeller 101b to a reverse rudder angle, here -105°, +105°, so that reverse thrust acts on the port side of the stern.This makes it possible to achieve spot turn to port maneuvering at low speeds without the need to reverse the propeller propellers 101a, 101b or increase power.

[0046] In the low-speed maneuvering mode, the left and right propulsion propellers 101a, 101b rotate at a constant low speed in the forward direction, and the turning speed adjustment function unit 207 controls the bow direction and turning speed by the tilt angle of the joystick lever 258.

[0047] For example, during the "turn right on the spot" maneuver shown in Figure 9 (n), the pair of starboard high-lift rudders 104a, 104b corresponding to one of the starboard propeller propellers 101a are controlled to maintain symmetrical rudder angles while increasing or decreasing them within the astern rudder angle range, here between -75° and -105° and between +75° and +105°, according to the tilt angle of the joystick lever 258, thereby increasing or decreasing the astern thrust on the starboard side of the stern.

[0048] Furthermore, during the "turn right on the spot" maneuver shown in Figure 9 (n), the forward thrust on the port side of the ship is increased or decreased by controlling the pair of port side high-lift rudders 105a, 105b corresponding to the other port side propulsion propeller 101b to maintain symmetrical rudder angles while increasing or decreasing them within the forward rudder angle range, here between -75° and 0° and between +75° and 0°, according to the tilt angle of the joystick lever 258.

[0049] Here, the pair of high-lift rudders 104a, 104b on both sides and the pair of high-lift rudders 105a, 105b may be controlled simultaneously, or only one of them may be controlled. The same applies to the "spot port turn" maneuver shown in Figure 9(b), and a description thereof will be omitted.

[0050] In this way, the turning speed during low-speed maneuvering is adjusted by controlling the moment around the stern acting on the hull without requiring reverse operation of the propulsion propellers 101a, 101b or power increase operation, thereby achieving maneuvering performance that allows easy control of the bow direction and turning speed.

[0051] During the navigation of the above-mentioned small unmanned vessel with two propellers and four rudders, the mission unit 500 performs various missions, such as observing meteorological and sea conditions at sea, observing the state of the seabed, collecting data such as biological and ecological measurements, patrolling and monitoring live aquaculture fish, scattering feed, collecting oil or garbage that causes marine pollution, and monitoring the marine ecosystem.

[0052] By replacing the mission unit 500 stored in the mission storage unit 600, the vehicle can be easily converted to another mission once one mission is completed. For example, the mission can be easily changed from observing meteorological and oceanographic conditions on the ocean floor to observing the state of the seabed, or from collecting data such as biological and ecological measurements. Also, the mission can be easily changed from patrolling and monitoring live aquaculture ponds to distributing feed. Furthermore, the mission can be easily changed from collecting oil or garbage, which are causes of marine pollution, to monitoring the marine ecosystem.

[0053] Therefore, the small, two-propeller, four-rudder unmanned vessel can be used without being specialized for a specific purpose. [Explanation of symbols]

[0054] 1 Own ship 100 Thrust System 101a, 101b propeller 102a, 102b electric motor 103a, 103b Thrust control device 104a, 104b, 105a, 105b High-lift rudders 106a, 106b, 107a, 107b Electric steering gear 108a, 108b, 109a, 109b Steering angle control device 200 Ship steering system 201 Ship steering control device 202 Ship steering control unit 203 Remote Control Device 204 Normal steering section 205 Low-speed steering section 206 Low-speed turning function 207 Turning speed adjustment function section 251 Antenna Equipment 252 1st monitor screen 253 Second monitor screen 254 Third monitor screen 255 4th monitor screen 256 Joystick operation unit 256 257 Low speed range steering switch button 258 Joystick Lever 300 Observation System 301 Marine radar equipment 302 GPS Compass 303 Transmitting and receiving antenna equipment 304 Surroundings camera of own ship 305 Infrared surveillance camera 400 Power supply section 401 Storage battery 402 solar panels 500 Mission Department 600 Mission Storage

Claims

1. The system comprises a thrust system, a maneuvering system for controlling the thrust system, and an observation system for observing the hull motion state of the ship itself; The observation system is equipped with a position measuring device that measures the ship's position and a monitoring device that monitors the ship's surroundings. The thrust system includes a pair of propeller shafts rotating in opposite directions, a pair of left and right propellers with opposite blade angles mounted on each propeller shaft and arranged at the stern, a pair of left and right high-lift rudders arranged behind each propeller, electric steering gears that respectively drive each high-lift rudders, and a rudder angle control device that controls the rudder angle of each high-lift rudders, The ship steering system comprises a ship steering control device that controls the electric steering gears of each high-lift rudders via a rudder angle control device, and operates each high-lift rudders independently at various angles with each steering gear while the left and right propellers rotate at a constant rate in the forward direction, and by changing the combination of rudder angles of the pair of high-lift rudders corresponding to each propeller, controls the direction of the propeller wake of each propeller and controls the direction of thrust acting around the stern on the hull; a ship steering instruction unit that instructs the ship steering control device on the direction of hull movement using an autonomous navigation program or remote ship steering; and a remote control device that instructs the ship steering instruction unit on the direction of hull movement via wireless communication. The remote control device has a monitor screen that displays the position information of the ship and a monitor screen that displays information about the surroundings of the ship, a joystick operation unit for manual steering, and a low-speed range steering switch button for switching the steering control device to low-speed range steering, A small unmanned ship with two shafts and four rudders is characterized in that the maneuvering control device has a low-speed on-the-spot turning function unit that, during low-speed maneuvering, sets a pair of high-lift rudders corresponding to one propeller to a reverse rudder angle and a pair of high-lift rudders corresponding to the other propeller to a forward rudder angle while the left and right propellers are rotating at a constant low speed in the forward direction, thereby performing on-the-spot turning maneuvering.

2. The small unmanned twin-propeller, four-rudder vessel according to claim 1, characterized in that the maneuvering control device has a turning speed adjustment function unit that, in low-speed maneuvering, controls a pair of high-lift rudders corresponding to one of the propulsion propellers to increase or decrease their rudder angles within a range of astern steering while maintaining symmetrical rudder angles, and controls a pair of high-lift rudders corresponding to the other propulsion propeller to increase or decrease their rudder angles within a range of forward steering while maintaining symmetrical rudder angles, and adjusts the turning speed during low-speed maneuvering by controlling the moment around the stern acting on the hull.

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