Fixed-point steering system for single-shaft, dual-rudder ships

Abstract

This invention provides a fixed-point steering system for a single-shaft, dual-rudder vessel that discretizes rudder angle and thruster thrust, thereby achieving high-precision positioning while reducing computational load. [Solution] The fixed-point holding maneuvering unit 281 includes a specific rudder angle instruction unit 284 that instructs to select one specific rudder angle set from among specific rudder angle sets of high-lift rudders, a specific rotation speed instruction unit 285 that instructs to select one specific rotation speed from among specific rotation speeds of the bow thruster, a target calculation unit 286 that calculates the hull position deviation distance, the ship's hull position deviation direction and the bow position deviation direction, a control amount calculation unit 287 that uses the combination of the specific rudder angle set and the specific rotation speed as a single control input value and calculates the motion force acting on the hull as a specific control amount for each of the multiple control input values, a control amount selection unit 288 that selects the optimal specific control amount from among the multiple specific control amounts, a maneuvering execution unit 289 that outputs the selected optimal specific control amount, and an execution command unit 290 that instructs each unit to repeat the execution cycle.

Description

Technical Field

[0001] The present invention relates to a fixed-point holding steering system for a single-shaft two-rudder ship, and pertains to a technology for performing simple ship position holding steering.

Background Art

[0002] Conventionally, as a technology for automatically performing ship position holding steering, for example, there is one described in Patent Document 1. This steering system includes a ship position holding control unit and a ship position holding motion control unit. The ship position holding control unit controls the rudder angles of each of the two high-lift rudders within a set rudder angle range of about ten degrees around the hover rudder angles δph and δsh of the left rudder -75° and the right rudder +75° where the hull stops in place as the center rudder angles. The ship position holding motion control unit controls each of the steering gears, and has a ship position holding steering control unit that controls the bow-stern direction speed and the ship width direction speed by combining the rudder angles of the two high-lift rudders, and a ship position holding thruster control unit that adjusts the thruster thrust of the bow thruster by a thruster control device to control the turning angular velocity. It controls the adjustment thruster control amount and the adjustment rudder angle control amount input from the ship position holding control unit by the ship position holding steering control unit and the ship position holding thruster control unit.

[0003] Also, a steering system having a steering angle correction function for a single-shaft two-rudder ship described in Patent Document 2 has a digital twin calculation unit that collects in real time the ship speed of the own ship measured by a ship speed measuring device, the ship position of the own ship measured by a position measuring device, and the bow azimuth of the own ship measured by an azimuth measuring device, and reproduces the actual hull motion of the own ship realized at the current steering angle on a nautical electronic chart. The simulation calculation unit displays the assumed hull motion of the own ship obtained by calculation assuming that the force acting on the hull is the driving force at the current steering angle on the nautical electronic chart. The external force resultant force calculation unit calculates the acting direction and magnitude of the resultant force of the external forces acting on the hull based on the ship speed difference, ship position difference, and bow azimuth difference between the actual hull motion and the assumed hull motion. The indicated rudder angle calculation unit calculates a correction rudder angle to resist the resultant force of the external forces, and corrects the current steering angle with the correction rudder angle to calculate the appropriate steering angle necessary to navigate the planned route against the external forces. [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2023-167025 [Patent Document 2] Japanese Patent Publication No. 2023-28183 [Overview of the project] [Problems that the invention aims to solve]

[0005] In recent years, research has been conducted in naval architecture and ocean engineering on autonomous and automated navigation. In particular, the automation of Dynamic Positioning Systems (DPS) has become an important issue. DPS is a technology mainly used in workboats and offshore structures to compensate for external forces such as waves, wind, and currents, and to maintain a predetermined position and attitude.

[0006] Conventional DPS control typically uses propellers or thrusters for thrust distribution, and various algorithms have been proposed to achieve optimal thrust control.

[0007] On the other hand, in a single-shaft, two-rudder ship with a pair of high-lift rudders positioned behind the propulsion propeller, the design of the optimal thrust distribution through combinations of rudder angles becomes more complex than in conventional propeller and thruster control systems.

[0008] Model Predictive Control (MPC) control methods can improve the control accuracy of the DPS by predicting future hull motion and calculating optimal rudder angles and thrust. However, challenges remain, such as increased computational costs and the need to ensure real-time performance.

[0009] The present invention aims to solve the above problems and provide a fixed-point steering system for a single-shaft, dual-rudder ship that can discretize the rudder angle and thruster thrust, thereby achieving high-precision position holding while reducing the computational load. [Means for solving the problem]

[0010] To solve the above-mentioned problems, the present invention provides a fixed-point steering system for a single-shaft, two-rudder ship comprising: a single propulsion propeller located at the stern; a pair of left and right high-lift rudders located behind the propulsion propeller; a pair of rotary vane steering gears that drive each high-lift rudder; a steering control device that controls the direction of the ship's movement by combining the rudder angles of the two high-lift rudders; a bow thruster; a thruster control device that controls the rotation speed of the bow thruster; a position measuring device that measures the ship's position; a direction measuring device that measures the ship's heading; and a fixed-point steering unit. This system includes a specific rudder angle instruction unit that instructs the steering control device to select one specific rudder angle combination from a plurality of specific rudder angle combinations set as combinations of rudder angles of two high-lift rudders, thereby controlling the motion force acting on the hull by the thrust of the propulsion propeller rotating forward at a constant speed; a specific rotation speed instruction unit that instructs the thruster control device to select one specific rotation speed from a plurality of specific rotation speeds set as the rotation speed of the bow thruster, thereby controlling the turning motion force acting on the hull by the thrust of the bow thruster; and a system that determines the hull position displacement distance and hull position from the difference in ship position between the ship's current position and a target point that maintains the ship's position at a fixed point. The target calculation unit calculates the deviation direction and calculates the bow position deviation direction from the difference in bow direction between the current bow direction of the ship and the target bow direction of the ship at the target point. The control quantity calculation unit sets multiple control input values ​​by combining each specific rudder angle set and each specific rotation speed, using a combination of one specific rudder angle set of one of the two high-lift rudders and one specific rotation speed of the bow thruster as one control input value, and calculates the motion force acting on the hull as a specific control quantity for each of the multiple control input values, and sets multiple specific directions discretely in all directions in the horizontal plane around the hull, and calculates a specific control quantity for each specific direction. A control quantity selection unit selects the optimal specific control quantity to maintain the ship at a target point from among multiple specific control quantities calculated by the control quantity calculation unit, based on the hull position deviation distance, hull position deviation direction, and bow position deviation direction calculated by the target calculation unit; a ship handling execution unit instructs the specific rudder angle instruction unit to specify the specific rudder angle set of the optimal specific control quantity selected by the control quantity selection unit, instructs the specific rotation speed instruction unit to specify the specific rotation speed, and outputs the selected optimal specific control quantity; the target calculation unit calculates the hull position deviation distance, hull position deviation direction, and bow position deviation direction; and the control quantity calculation unit calculates multiple specific control quantities.It is characterized by having a control quantity selection unit that selects the optimal specific control quantity, and an execution command unit that instructs the ship operation execution unit to repeatedly output the optimal specific control quantity at a set execution cycle.

[0011] Furthermore, the fixed-point holding maneuvering system for a single-shaft, two-rudder ship of the present invention is characterized in that the single-shaft, two-rudder ship has an external force calculation unit that calculates external forces acting on the hull, a control quantity selection unit that selects an optimal specific control quantity to hold the ship at a fixed point at a target point based on the hull position deviation distance, hull position deviation direction, bow position deviation direction calculated by the target calculation unit and the external force calculated by the external force calculation unit, and an execution command unit that instructs the calculation of the hull position deviation distance, hull position deviation direction and bow position deviation direction by the target calculation unit, the calculation of external forces by the external force calculation unit, the calculation of a plurality of specific control quantities by the control quantity calculation unit, the selection of the optimal specific control quantity by the control quantity selection unit and the output of the optimal specific control quantity by the maneuvering execution unit to be repeated in a set execution cycle.

[0012] Furthermore, the fixed-point holding maneuvering system for a single-shaft, two-rudder vessel of the present invention is characterized in that the fixed-point holding maneuvering unit has a position estimation unit that estimates the predicted ship position and predicted heading to be reached by the ship for each execution cycle based on the optimal specific control amount output by the maneuvering execution unit, and the target calculation unit calculates the hull position deviation distance, hull position deviation direction and bow position deviation direction in the first execution cycle, using the ship position measured by the position measuring device as the current ship position and the ship heading measured by the heading measuring device as the current heading, and in subsequent execution cycles, calculates the hull position deviation distance, hull position deviation direction and bow position deviation direction using the predicted ship position estimated by the position estimation unit as the current ship position and the predicted heading as the current heading.

[0013] Furthermore, the fixed-point holding maneuvering system for a single-shaft, two-rudder vessel of the present invention is characterized in that the target calculation unit calculates the hull position deviation distance, hull position deviation direction, and bow position deviation direction in each execution cycle, using the position of the vessel measured by the position measuring device as the current position and the heading of the vessel measured by the heading measuring device as the current heading.

[0014] Furthermore, the fixed-point steering system for a single-shaft, two-rudder ship of the present invention is characterized in that the specific rudder angle combination of the two high-lift rudders is a combination of rudder angles that produces any of the following ship movements: forward left turn, bow left turn, stern left turn, reverse left turn, forward, stop in place, reverse, forward right turn, bow right turn, stern right turn, and reverse right turn, and the specific rotational speed of the bow thruster is a rotational speed that produces either a complete stop or a right turn or left turn.

[0015] Furthermore, the fixed-point steering system for a single-shaft, two-rudder ship of the present invention allows for specific rudder angle combinations of the two high-lift rudders to be: a combination of port rudder -35°, starboard rudder -35°; a combination of port rudder -70°, starboard rudder -35°; a combination of port rudder -105°, a specific value between starboard rudder +45° and +75°; a combination of port rudder -105°, a specific value between starboard rudder +75° and +105°; a specific value between port rudder 0° and -5°, a specific value between starboard rudder 0° and +5°; a specific value between port rudder -75° and -70°, a combination of starboard rudder +75° and +70°; or port rudder -105° The specific rotational speed of the bow thruster is one of the following: a specific value between - and -100°, a specific value between +105° and +100° for the starboard rudder, or a combination of +35° for the port rudder and +35° for the starboard rudder, or a combination of +35° for the port rudder and +70° for the starboard rudder, or a combination of -45° to -75° for the port rudder and +105° for the starboard rudder, or a combination of -75° to -105° for the port rudder and +105° for the starboard rudder. The specific rotational speed of the bow thruster is characterized by being a rotational speed that produces one of the following hull motions: no rotation (0 rps), right turn (15 rps), right turn (30 rps), left turn (-15 rps), or left turn (-30 rps). [Effects of the Invention]

[0016] With the above configuration, the fixed-point holding navigation unit calculates a specific control amount for a specific azimuth discretely set around the hull based on a plurality of control input values discretely set by the control amount calculation unit by combining a specific rudder angle set and a specific rotational speed. The control amount selection unit selects an optimal specific control amount for holding the own ship at the target point from the specific control amounts calculated by the control amount calculation unit, and the navigation execution unit repeatedly outputs this optimal specific control amount in an execution cycle, so that the own ship gradually approaches the target point and holds the fixed point at the target point.

[0017] Therefore, by repeatedly outputting discrete specific control amounts to perform fixed-point holding, it is possible to achieve fixed-point holding while suppressing the computational load without requiring sophisticated and complex calculations for linearly approaching the own ship to the target point.

Brief Description of the Drawings

[0018] [Figure 1] Schematic diagram showing the thrust system, navigation system, and observation system of a single-shaft two-rudder ship in an embodiment of the present invention [Figure 2] Schematic diagram showing the propeller, high-lift rudder, and bow thruster in the same embodiment [Figure 3] Perspective view showing the configuration of the stern part in the same embodiment [Figure 4] Schematic diagram showing the navigation stand of the steering control device of a single-shaft two-rudder ship in the same embodiment [Figure 5] Block diagram showing the configuration of the navigation stand in the same embodiment [Figure 6] Plan view showing the movable range of the high-lift rudder in the same embodiment [Figure 7] Schematic diagram showing the combined rudder angle and turning direction of the rudders [Figure 8] Schematic diagram showing the concept of fixed-point holding navigation in the same embodiment [Figure 9] Schematic diagram showing the movement of the hull during fixed-point holding navigation in the same embodiment

Embodiments for Carrying Out the Invention

[0019] Hereinafter, embodiments of the rudder system of the present invention will be described with reference to the drawings. (Configuration of the example) The steering system for a single-shaft, dual-rudder ship in this embodiment, which has a steering angle correction function, consists of a thrust system 100 and a steering system (steering control device) 200 that controls the thrust system 100, as shown in Figures 1 to 6.

[0020] The thrust system 100 consists of a propulsion propeller 101, which is a single-shaft propeller located at the stern of the hull 110, and two high-lift rudders 102 and 103 located behind the propeller.

[0021] Each of the high-lift rudders 102 and 103 is configured to be steerable 105° outboard and 35° inboard. With the single propeller rotating forward, the pair of high-lift rudders 102 and 103 can be operated independently at various angles. By changing the combination of rudder angles of the high-lift rudders 102 and 103 on both sides, the propeller wake can be distributed in the desired direction, and the thrust in each direction can be freely changed. Therefore, the combined thrust of the thrust in each direction can be freely changed, and by controlling the propeller wake and controlling the thrust around the stern in all 360° directions, the ship's movement can be freely controlled, allowing for forward and backward movement, stopping, forward turns, and reverse turns.

[0022] Furthermore, the thrust system 100 includes rotary vane steering gears 104 and 105 that drive high-lift rudders 102 and 103, and rudder control devices (servo amplifiers) 106 and 107 that control the rotary vane steering gears 104 and 105. It also includes a bow thruster 108 located on the bow side of the hull 110 and a thruster control device 109 that controls the bow thruster 108.

[0023] Furthermore, the rotary vane steering gears 104 and 105 are connected to pump units 151 and 152, rudder angle transmitters 153 and 154, and feedback units 155 and 156, respectively, and the feedback units 155 and 156 are connected to rudder control devices 106 and 107.

[0024] The ship steering system (steering control device) 200 is housed in the ship steering stand 250, which is connected to a gyrocompass 251, a ship radar device 310, a ship speed measuring device 312 for measuring the ship's speed, a position measuring device 313 for measuring the ship's position using GPS or the like, and a direction measuring device 314 for measuring the ship's heading. The ship radar device 310 transmits a collision warning signal from its warning signal output unit 311 to the ship steering system (steering control device) 200 in the ship steering stand 250 when a collision with another ship is predicted.

[0025] The steering stand 250 integrates the following into the stand housing: a gyro direction display unit 252 that displays the gyro direction of the gyro compass 251; an auto steering unit 253 that operates the ship in an autopilot mode using a GPS compass; a joystick steering unit 255 that operates the ship in a joystick lever mode 254; a manual steering unit 257 that operates the ship in a manual steering wheel mode 256; a non-follow-up steering unit 259 that operates the ship in a non-follow-up steering lever mode 258; and a mode switching unit 261 that switches between each steering unit using a mode switching switch 260.

[0026] Furthermore, the system includes a display device 262 with a touch panel on the screen, an image control unit 263 that controls the images displayed on the display device 262, an emergency stop unit 265 that operates the ship in a mode that takes precedence over all other operating modes by operating an emergency stop push button 264, a rudder angle indicator unit 280 that gives an indicated rudder angle to the rotary vane steering gears 104 and 105 via rudder control devices 106 and 107, a fixed-point holding operation unit 281 that holds the ship at a fixed point at a target point set on the nautical electronic chart, an electronic chart display unit 282 that displays the nautical electronic chart on the display device 262, and a fixed-point holding start push button 283 that activates the fixed-point holding operation unit 281.

[0027] The image control unit 263 selectively displays, or simultaneously displays, a chart display image 266 showing an electronic nautical chart, a gyro bearing display image 267 showing the gyro bearing, a bearing display unit operation image 268 for touch operation of the gyro bearing display unit 252 on the monitor screen, and an auto steering operation image 269 for touch operation of the auto steering unit 253 on the monitor screen.

[0028] The joystick control unit 255 is configured such that the joystick lever 254 can be operated in either the X or Y direction. The direction of tilt of the joystick lever 254 controls the commanded direction of the ship's movement, and the tilt angle in the tilting direction controls the commanded speed in the bow and stern direction and the commanded speed in the lateral direction of the ship.

[0029] The joystick steering unit 255 controls the rudder angles of the high-lift rudders 102 and 103 on both sides to the rudder angles set according to the tilt direction of the joystick lever 254, and by combining the rudder angles of the high-lift rudders 102 and 103 on both sides, it redirects the thrust of the propeller wake in the desired direction, and the rotary vane steering gears 104 and 105 on both sides control the rudder angles of the high-lift rudders 102 and 103 on both sides within a range of 105° outward and 35° inward.

[0030] The basic combinations of rudder angles for the high-lift rudders 102 and 103, as well as the state of the joystick lever 254, their designations, and the propeller wake and direction of motion are explained in Figures 6 and 7.

[0031] In Figures 6 and 7, the rudder is shown in a horizontal cross-section, with the rudder angle of each rudder indicated to the side or below. A rudder angle to the right is indicated as positive (+) and a rudder angle to the left is indicated as negative (-), and the names for these combinations of rudder angles are listed. The propeller wake is shown with a thin arrow line, and the resulting direction of the ship's propulsion is shown with a thick, hollow arrow line.

[0032] Incidentally, "forward left turn" is -35° port rudder, -35° starboard rudder, "bow left turn" is -70° port rudder, -35° starboard rudder, "stern left turn" is -105° port rudder, +45° to +75° starboard rudder, "reverse left turn" is -105° port rudder, +75° to +105° starboard rudder, "forward" is 0° to -5° port rudder, 0° to +5° starboard rudder, and "stop in place" is -75° to -70° port rudder. For a starboard rudder, the range is +75° to +70°. For "reverse," the range is -105° to -100° for the port rudder and +105° to +100° for the starboard rudder. For "forward right turn," the range is +35° for the port rudder and +35° for the starboard rudder. For "bow right turn," the range is +35° for the port rudder and +70° for the starboard rudder. For "stern right turn," the range is -45° to -75° for the port rudder and +105° for the starboard rudder. For "reverse right turn," the range is -75° to -105° for the port rudder and +105° for the starboard rudder.

[0033] Thus, a single-shaft, two-rudder ship equipped with two high-lift rudders 102 and 103 can freely vary the direction and magnitude of the thrust in all directions of the ship by changing the combination angle of the high-lift rudders 102 and 103.

[0034] The automatic steering unit 253 uses a GPS compass and an electronic chart system to guide and control the vessel to a predetermined set course based on the vessel's current position information, guidance route information, and stationary position information.

[0035] The emergency stopping unit 265, when the emergency stop push button 264 is pressed in an emergency, cancels the current steering angle and turns the port rudder 103 to port (clockwise when viewed from above) and the starboard rudder 102 to starboard (counterclockwise when viewed from above), respectively, to hardover (full rudder), thereby applying braking force to the ship and bringing it to a stop.

[0036] The manual steering unit 257 controls the rudder angles of the two high-lift rudders 102 and 103 by rotating the manual steering wheel 256 to steer the ship.

[0037] The non-follow-up steering unit 259 steers to starboard or port depending on the duration of time the non-follow-up steering lever 258 is operated left or right.

[0038] The fixed-point holding maneuvering unit 281 includes a specific rudder angle indicator unit 284, a specific rotation speed indicator unit 285, a target calculation unit 286, a control amount calculation unit 287, a control amount selection unit 288, a maneuvering execution unit 289, an execution command unit 290, an external force calculation unit 291, and a ship position estimation unit 292.

[0039] The specific rudder angle instruction unit 284 instructs the steering control device 200 to select one specific rudder angle set from among several specific rudder angle sets set as combinations of rudder angles of the two high-lift rudders 102 and 103, and via the rudder control devices 106 and 107, it provides each rudder angle of the specific rudder angle set to the rotary vane steering gears 104 and 105, thereby controlling the motion force acting on the hull 110 by the thrust of the propulsion propeller 101 which rotates forward at a constant speed.

[0040] Here, we have 11 specific rudder angle combinations: a specific rudder angle combination of -35° port rudder and -35° starboard rudder for "forward left turn", a specific rudder angle combination of -70° port rudder and -35° starboard rudder for "bow left turn", a specific rudder angle combination of -105° port rudder and a specific value between +45° and +75° starboard rudder for "stern left turn", a specific rudder angle combination of -105° port rudder and a specific value between +75° and +105° starboard rudder for "reverse left turn", a specific rudder angle combination of a specific value between 0° and -5° port rudder and a specific value between 0° and +5° starboard rudder for "forward", and a specific value between -75° and -70° port rudder for "stop in place". These include specific rudder angle combinations of a constant value and a specific value between +75° and +70° for the starboard rudder, specific rudder angle combinations of a specific value between -105° and -100° for the port rudder and a specific value between +105° and +100° for the starboard rudder for "reverse," specific rudder angle combinations of +35° for the port rudder and +35° for the starboard rudder for "forward right turn," specific rudder angle combinations of +35° for the port rudder and +70° for "bow right turn," specific rudder angle combinations of a specific value between -45° and -75° for the port rudder and +105° for "stern right turn," and specific rudder angle combinations of a specific value between -75° and -105° for the port rudder and +105° for "reverse right turn."

[0041] The specific rotation speed instruction unit 285 instructs the thruster control device 109 to select one specific rotation speed from among several specific rotation speeds set as the rotation speed of the bow thruster 108, thereby controlling the turning force acting on the hull 110 due to the propulsion force of the bow thruster 108.

[0042] Here, we define five specific rotation speeds: rotation stopped at 0 (rps), right turn at 15 (rps), right turn at 30 (rps), left turn at -15 (rps), and left turn at -30 (rps).

[0043] The target calculation unit 286 calculates the hull position deviation distance and hull position deviation direction from the difference in ship position between the ship's current position and the target point that holds the ship in a fixed position, and calculates the bow position deviation direction from the difference in bow heading between the ship's current bow heading and the ship's target bow heading at the target point.

[0044] The control quantity calculation unit 287 sets 55 different control input values ​​by taking a combination of one specific rudder angle set of the two high-lift rudders 102 and 103 and one specific rotation speed of the bow thruster 108 as one control input value, and combining 11 different specific rudder angle sets with 5 different specific rotation speeds.

[0045] Then, the kinetic force acting on the hull 110 for each of the multiple control input values ​​is calculated as a specific control quantity, and multiple specific control quantities for 55 specific directions, which are discretely set across all directions in the horizontal plane around the hull 110, are calculated.

[0046] The external force calculation unit 291 calculates the external forces acting on the hull 110. Here, it calculates the external force that the hull 110 receives due to the wind.

[0047] The control quantity selection unit 288 selects the optimal specific control quantity for maintaining the ship at a fixed point at the target point, based on the hull position deviation distance, hull position deviation direction, and bow position deviation direction calculated by the target calculation unit 286, and the external force calculated by the external force calculation unit 291.

[0048] The ship handling execution unit 289 instructs the specific rudder angle instruction unit 284 to specify the optimal specific control amount and specific rudder angle set selected by the control amount selection unit 288, instructs the specific rotational speed instruction unit 285 to specify the specific rotational speed, and outputs the selected optimal specific control amount.

[0049] The execution command unit 290 instructs the target calculation unit 286 to calculate the hull position deviation distance, hull position deviation heading, and bow position deviation heading, the external force calculation unit 291 to calculate the external force, the control amount calculation unit 287 to calculate multiple specific control amounts, the control amount selection unit 288 to select the optimal specific control amount, and the ship handling execution unit 289 to output the optimal specific control amount, all of which are repeated in a set execution cycle. The calculation of multiple specific control quantities by the control quantity calculation unit 287 is performed only in the first execution cycle, and it is also possible to repeatedly use the multiple specific control quantities calculated in the first execution cycle in subsequent execution cycles. In other words, by calculating the kinetic force acting on the hull 110 for each of the multiple control input values ​​as a specific control quantity, calculating specific control quantities for multiple specific directions discretely set across all directions in the horizontal plane around the hull 110, and registering the specific control quantities for multiple specific directions around the hull 110 as a group of specific control quantities, the computational load can be reduced and the optimal specific control quantity can be selected quickly.

[0050] Furthermore, if the external force calculated by the external force calculation unit 291 is not considered, the control quantity selection unit 288 selects the optimal specific control quantity from among the multiple specific control quantities calculated by the control quantity calculation unit 287, based on the hull position deviation distance, hull position deviation direction, and bow position deviation direction calculated by the target calculation unit 286, in order to maintain the ship at a fixed point.

[0051] The execution command unit 290 then instructs the target calculation unit 286 to repeatedly perform the calculation of hull position deviation distance, hull position deviation heading, and bow position deviation heading, the control amount calculation unit 287 to calculate multiple specific control amounts, the control amount selection unit 288 to select the optimal specific control amount, and the ship handling execution unit 289 to output the optimal specific control amount, all within a set execution cycle.

[0052] The ship position estimation unit 292 estimates the predicted ship position and predicted heading of the ship to be reached for each execution cycle based on the optimal specific control quantity output by the ship maneuvering execution unit 289.

[0053] In the first execution cycle, the target calculation unit 286 uses the ship's position measured by the position measuring device 313 as the current ship's position and the ship's heading measured by the heading measuring device 314 as the current heading, and calculates the hull position deviation distance, hull position deviation heading, and bow position deviation heading.

[0054] Then, in subsequent execution cycles, the predicted ship position estimated by the ship position estimation unit 292 is used as the current ship position, and the predicted heading is used as the current heading to calculate the hull position deviation distance, hull position deviation heading, and heading.

[0055] Furthermore, if the prediction of the ship's position and predicted heading by the ship's position estimation unit 292 is not taken into consideration, the target calculation unit 286 calculates the hull position deviation distance, hull position deviation heading, and heading deviation heading by taking the ship's position measured by the position measuring device 313 as the current ship's position and the ship's heading measured by the heading measuring device 314 as the current heading in each execution cycle.

[0056] The following explains the operation of the above configuration. 1. Joystick control mode The mode selection mode is performed by operating the mode selector switch 260. The joystick control unit 255 commands the ship's commanded direction of movement, the commanded thrust in the bow and stern directions, and the commanded thrust in the lateral direction of the ship using the joystick lever 254.

[0057] In this maneuver, the propulsion propeller 101 is kept rotating forward, while the high-lift rudders 102 and 103 are operated independently at various angles to control the propeller wake and control the thrust around the stern in all 360 degrees. This control allows the ship to move forward and backward, stop, turn forward, turn backward, etc., thereby improving the maneuverability during operation.

[0058] In other words, by changing the combination of rudder angles on both sides, the thrust can be directed in the desired direction of the propeller wake. The rudder angle combinations listed here are just examples, and the combination of rudder angles can be arbitrarily changed to obtain the desired propulsion direction and thrust.

[0059] Thus, in ship handling, reversing the propeller thrust (reversing the propeller rotation) is unnecessary, and all ship handling controls can be performed while the main engine is always rotating forward. Without adjusting the rotation speed of the main engine, the ship's speed can be precisely controlled steplessly from the maximum forward speed corresponding to the current propeller rotation speed to the maximum reverse speed by adjusting the rudder angles of both rudders. 2. Control mode via emergency stopping section By pressing the emergency stop button 264, the emergency stop unit 265 is activated, allowing the vessel to be brought to an emergency stop in priority over all other steering modes. In other words, regardless of the steering mode of the joystick lever 254, or any other steering mode, the emergency stop unit 265 switches to crash astern mode ("ASTERN" mode, where the port rudder is set to 105° to the left and the starboard rudder to 105° to the right), generating very large braking and reverse forces from both rudders, allowing the vessel to be stopped in a much shorter time and distance than by steering with the propellers reversed.

[0060] Furthermore, even in crash astern mode, there is no need to stop the main engine and restart it in reverse, so the vessel does not become uncontrolled during operation, allowing for a quick response to any situation during navigation.

[0061] Furthermore, if the ship turns due to its characteristics, external disturbances, etc., while maneuvering using the emergency stopping section 265, or if it is necessary to change the direction of travel, including the heading, the ship can be freely steered and navigated to avoid obstacles by operating the joystick lever 254 in the same way as normal joystick operation. 3. Autopilot control mode During normal navigation and operation, the autopilot control mode is selected by operating the mode selector switch 260.

[0062] An image 269 of the automatic ship steering operation is displayed on the monitor screen of the display device 262. The ship's position, desired direction, and destination position or bow-stern direction are input to the automatic ship steering unit 253 by touch operation on the monitor screen, and the ship is automatically guided and steered along the set course.

[0063] The autopilot unit 253 controls the rudder angle as appropriate based on the ship's current position information, guidance path information, and stationary position information. The autopilot maintains the course indicated by the gyrocompass as the desired heading or bow-stern heading set in the autopilot operation image 269. 4. Manual control mode The mode selection switch 260 is operated to select the steering mode using the manual steering wheel 256. In this steering mode, the rotation of the manual steering wheel 256 instructs the manual steering unit 257 to control the rudder angles of the two high-lift rudders 102 and 103, thereby steering the ship. 5. Non-follow-up control mode The mode selection switch 260 is operated to select the non-follow-up steering lever 258 steering mode. In this steering mode, the non-follow-up steering unit 259 steers the ship to starboard or port depending on the duration of time the non-follow-up steering lever 258 is operated left or right. 6. Maneuvering mode for fixed-point keeping maneuvering (See Figures 8 and 9 below.) To maintain the ship S at a fixed point X0 set on the navigational electronic chart, the fixed point holding activation push button 283 is pressed to activate the fixed point holding steering unit 281.

[0064] The fixed-point holding maneuvering unit 281 calculates the hull position deviation distance L and hull position deviation heading Dx from the difference in position between the current position X1 of the vessel S and the target point X0 that holds the vessel in a fixed position, using the target calculation unit 286, and calculates the bow position deviation heading BDx from the difference in bow heading between the current bow heading BD1 of the vessel S and the target bow heading BD0 of the vessel at the target point X0.

[0065] The control quantity calculation unit 287 calculates the kinetic force acting on the hull 110 as a specific control quantity U for each of the 55 different control input values, and calculates multiple specific control quantities U1-U55 for 55 specific directions, which are discretely set in all directions within the horizontal plane around the hull 110.

[0066] The external force calculation unit 291 calculates the external force F acting on the hull 110. Here, it calculates the external force F that the hull 110 receives due to the wind.

[0067] The control quantity selection unit 288 selects the optimal specific control quantity U from among the previously calculated specific control quantities U1-U55 for a specific direction in order to maintain the ship S at a fixed point X0, based on the hull position deviation distance L, hull position deviation heading Dx, bow position deviation heading BDx calculated by the target calculation unit 286, and the external force F calculated by the external force calculation unit 291. This selected specific control quantity U is the specific control quantity U that most approximates the motion force that moves the hull 110 linearly toward the target point X0.

[0068] In this case, the selected specific control quantity U is a combination of "turn left stern" LT and "turn right" RT.

[0069] Furthermore, if the external force F calculated by the external force calculation unit 291 is not considered, the control quantity selection unit 288 selects the optimal specific control quantity U from among the multiple specific control quantities U1-U55 calculated by the control quantity calculation unit 287, based on the hull position deviation distance L, hull position deviation heading Dx, and bow position deviation heading BDx calculated by the target calculation unit 286, in order to maintain the ship S at the target point X0.

[0070] The execution command unit 290 then instructs the target calculation unit 286 to calculate the hull position deviation distance L, hull position deviation heading Dx, and bow position deviation heading BDx, the control amount calculation unit 287 to calculate multiple specific control amounts U1-U55, the control amount selection unit 288 to select the optimal specific control amount U, and the ship maneuvering execution unit 289 to output the optimal specific control amount U, and to repeat these actions in a set execution cycle. As shown in Figure 9, the hull 110 gradually approaches the target point X0 and target bow heading BD0 with each execution cycle and is maintained at a fixed point.

[0071] The ship position estimation unit 292 estimates the predicted ship position and predicted heading that the ship S will reach for each execution cycle based on the optimal specific control quantity U output by the ship maneuvering execution unit 289.

[0072] In the first execution cycle, the target calculation unit 286 uses the position of the vessel S measured by the position measuring device 313 as the current position X1, and the heading of the vessel S measured by the heading measuring device 314 as the current heading BD1, and calculates the hull position deviation distance L, the hull position deviation heading Dx, and the heading deviation heading BDx.

[0073] Then, in subsequent execution cycles, the predicted ship position estimated by the ship position estimation unit 292 is set as the current ship position X1, and the predicted heading is set as the current heading BD1, and the ship position deviation distance L, ship position deviation heading Dx, and heading deviation heading BDx are calculated.

[0074] Furthermore, if the prediction of the ship's position and predicted heading by the ship's position estimation unit 292 is not taken into consideration, the target calculation unit 286 calculates the ship's position deviation distance L, the ship's position deviation heading Dx, and the ship's position deviation heading BDx in each execution cycle, using the ship's position measured by the position measuring device 313 as the current ship's position X1 and the ship's heading measured by the heading measuring device 314 as the current heading BD1. [Explanation of Symbols]

[0075] 100 Thrust System 110 hull 101 Propulsion propeller 102, 103 High-lift rudder 104, 105 Rotary vane steering gear 106, 107 Rudder control device 108 Bow thruster 109 Thruster control device 151, 152 Pump Units 153, 154 Rudder angle transmitters 155, 156 Feedback Unit 200 ship handling systems 250 Steering Stand 251 Gyrocompass 252 Gyro Direction Display Unit 253 Automatic steering unit 254 Joystick Lever 255 Joystick Control Unit 262 Display devices 263 Image Control Unit 264 Emergency stop push button 265 Emergency Stopping Department 266 Chart display image 267 Gyroscope Direction Display Image 268 Direction display section operation image 269 ​​Auto-Ship Operation Images 280 Rudder angle indicator 281 Fixed-point steering unit 282 Electronic Chart Display Unit 283 Fixed point hold start push button 284 Specific rudder angle indicator 285 Specific rotation speed indicator 286 Target Calculation Unit 287 Control Variable Calculation Unit 288 Control Variable Selection Unit 289 Rudder Angle Calculation Unit 290 Execution Command Unit 291 External force calculation section 292 Ship position estimation section 310 Ship radar equipment 311 Alarm signal output section 312 Ship speed measuring device 313 Position Measuring Device 314 Direction measuring device

Claims

1. In a single-shaft, two-rudder ship, the vessel is equipped with a single propulsion propeller located at the stern, a pair of high-lift rudders positioned behind the propulsion propeller, a pair of rotary vane steering gears that drive each of the high-lift rudders, a steering control device that controls the direction of the ship's movement by combining the rudder angles of the two high-lift rudders, a bow thruster, a thruster control device that controls the rotation speed of the bow thruster, a position measuring device that measures the ship's position, a direction measuring device that measures the ship's heading, and a fixed-point steering unit. The fixed-point steering unit instructs the steering control device to select one specific rudder angle combination from a plurality of specific rudder angle combinations set as combinations of rudder angles of two high-lift rudders, and controls the motion force acting on the hull by the thrust of the propulsion propeller rotating forward at a constant speed. A specific rotation speed instruction unit controls the turning force acting on the hull due to the bow thruster's propulsion by instructing the thruster control device to select one specific rotation speed from among several specific rotation speeds to be set as the rotation speed of the bow thruster. A target calculation unit calculates the hull position deviation distance and hull position deviation direction from the difference in ship position between the ship's current position and a target point that holds the ship in place, and calculates the bow position deviation direction from the difference in bow heading between the ship's current bow heading and the ship's target bow heading at the target point. A control quantity calculation unit sets multiple control input values ​​by taking a combination of a specific rudder angle set of one of two high-lift rudders and a specific rotation speed of one of the bow thrusters as a single control input value, calculating the kinetic force acting on the hull as a specific control quantity for each of the multiple control input values, setting multiple specific directions discretely across all directions in the horizontal plane around the hull, and calculating a specific control quantity for each specific direction. A control quantity selection unit selects the optimal specific control quantity from among multiple specific control quantities calculated by the control quantity calculation unit, based on the hull position deviation distance, hull position deviation direction, and bow position deviation direction calculated by the target calculation unit, in order to maintain the ship at a fixed point. The ship handling execution unit instructs the specific rudder angle instruction unit to select the optimal specific control amount and specific rudder angle set selected by the control amount selection unit, instructs the specific rotation speed instruction unit to select a specific rotation speed, and outputs the selected optimal specific control amount. A fixed-point holding maneuvering system for a single-shaft, two-rudder vessel, characterized by having a target calculation unit that calculates the hull position deviation distance, hull position deviation heading, and bow position deviation heading; a control quantity calculation unit that calculates multiple specific control quantities; a control quantity selection unit that selects the optimal specific control quantity; and an execution command unit that instructs the operation execution unit to repeatedly perform the output of the optimal specific control quantity at a set execution cycle.

2. A single-shaft, two-rudder ship has an external force calculation unit that calculates the external forces acting on the hull. The control quantity selection unit selects the optimal specific control quantity for maintaining the ship at a fixed point at the target point, based on the hull position deviation distance, hull position deviation direction, and bow position deviation direction calculated by the target calculation unit, and the external force calculated by the external force calculation unit. The fixed-point holding maneuvering system for a single-shaft, two-rudder vessel according to claim 1, characterized in that the execution command unit instructs the target calculation unit to repeatedly perform the calculation of hull position deviation distance, hull position deviation heading, and bow position deviation heading, the external force calculation unit to calculate external forces, the control amount calculation unit to calculate multiple specific control amounts, the control amount selection unit to select the optimal specific control amount, and the maneuvering execution unit to output the optimal specific control amount, in a set execution cycle.

3. The fixed-point holding maneuvering unit has a ship position estimation unit that estimates the predicted ship position and predicted heading of the ship to be reached for each execution cycle based on the optimal specific control quantity output by the maneuvering execution unit. The target calculation unit, in the first execution cycle, uses the ship's position measured by the position measuring device as the current ship's position and the ship's heading measured by the heading measuring device as the current heading, and calculates the hull position deviation distance, hull position deviation heading, and bow position deviation heading. A fixed-point steering system for a single-shaft, two-rudder vessel according to claim 1 or 2, characterized in that, in subsequent execution cycles, the predicted ship position estimated by the ship position estimation unit is used as the current ship position, and the predicted heading is used as the current heading to calculate the hull position deviation distance, hull position deviation direction, and heading direction.

4. The fixed-point steering system for a single-shaft, two-rudder vessel according to claim 1 or 2, characterized in that the target calculation unit calculates the hull position deviation distance, hull position deviation direction, and bow position deviation direction in each execution cycle, using the position of the vessel measured by the position measuring device as the current position and the bow heading measured by the heading measuring device as the current heading.

5. The specific rudder angle combinations of the two high-lift rudders are combinations of rudder angles that produce one of the following ship movements: forward left turn, bow left turn, stern left turn, reverse left turn, forward, stationary, reverse, forward right turn, bow right turn, stern right turn, or reverse right turn. The fixed-point steering system for a single-shaft, two-rudder ship according to claim 1 or 2, characterized in that the specific rotational speed of the bow thruster is a rotational speed that results in either a halt in rotation or a rightward or leftward turn of the hull.

6. The specific rudder angle combinations for the two high-lift rudders are: a combination of port rudder -35°, starboard rudder -35°; a combination of port rudder -70°, starboard rudder -35°; a combination of port rudder -105°, a specific value between starboard rudder +45° and +75°; a combination of port rudder -105°, a specific value between starboard rudder +75° and +105°; a specific value between port rudder 0° and -5°, a specific value between starboard rudder 0° and +5°; or a specific value between port rudder -75° and -70°, starboard rudder + One of the following combinations of values: a specific value between 75° and +70°, or a specific value between -105° and -100° for port rudder and a specific value between +105° and +100° for starboard rudder, or a combination of +35° for port rudder and +35° for starboard rudder, or a combination of +35° for port rudder and +70° for starboard rudder, or a specific value between -45° and -75° for port rudder and +105° for starboard rudder, or a specific value between -75° and -105° for port rudder and +105° for starboard rudder. The fixed-point steering system for a single-shaft, two-rudder ship according to claim 1 or 2, characterized in that the specific rotational speed of the bow thruster is a rotational speed that produces any of the following ship motions: rotation stop 0 (rpm), right turn 15 (rpm), right turn 30 (rpm), left turn -15 (rpm), or left turn -30 (rpm).

Images