Automatic Steering System for Ships

Abstract

To provide a technology capable of automatically berthing and un-berthing a ship.SOLUTION: An automatic steering system for a ship comprises: a reference trajectory generating unit for generating a reference trajectory which includes a trajectory from a departure point to an arrival point, a reference distance that is a time function of a surge direction distance from the departure point to the arrival point, and a reference azimuth that is a time function of the azimuth based on a planned route; a movement control unit 121 for controlling the ship by a distance control that causes a position of the ship to follow the reference distance, and a route control that causes the position of the ship to follow the trajectory and the azimuth of the ship to follow the reference azimuth; a holding control unit 122 for controlling the ship to hold the position of the ship; and a switching unit 123 for switching from the control by the movement control unit to the control by the holding control unit when an intersection of a line extending from the position of the ship in a sway direction of the ship and the trajectory reaches the arrival point.SELECTED DRAWING: Figure 13

Description

[Technical field]

[0001] The present invention relates to a technique for automatically steering a ship. [Background technology]

[0002] In recent years, research and development into ship navigation technology for berthing and unberthing has been actively pursued. To achieve berthing and unberthing navigation, ship position control technology is required to move the ship's position from the departure point, turn it on the way, and stop it at the destination. Compared to automobiles, ships have a large inertia and a weak braking force, and fluid resistance is also weak at low speeds, so it is not easy to control a ship to stop. [Prior art documents] [Non-patent literature]

[0003] [Non-Patent Document 1] Fuyuki Hane, “Design of Berthing Control System Including Speed ​​Control Using Compass”, Proceedings of the Japan Society of Naval Architects and Ocean Engineers Conference, 2019, 29:497-503 [Non-Patent Document 2] Fuyuki Hane, “Design of a Positioning System by Decoupling and Route Sequence”, Proceedings of the Japan Society of Naval Architects and Ocean Engineers Conference, May 2020, (30): 33-41 [Non-Patent Document 3] Fuyuki Hane, “Design of Course-Keeping System by Analytical Method Based on Course-Keeping Control”, Journal of the Japan Society of Naval Architects and Ocean Engineers, January 2016, 23:33-44 Summary of the Invention [Problem to be solved by the invention]

[0004] The problem to be solved by the present invention is to provide a technique that enables a ship to automatically dock and undock. [Means for solving the problem]

[0005] An embodiment of an automatic steering device for a ship is an automatic steering device for a ship that controls a ship equipped with a propulsion drive unit capable of controlling the speed in the surge direction and the sway direction and the angular velocity around the yaw, and a sensor that detects the bow heading and the hull position, and is equipped with a reference trajectory generation unit that generates a reference trajectory based on a planned route, the reference trajectory including a trajectory from a starting point to a destination point, a reference distance which is a time function of the surge direction distance from the starting point to the destination point, and a reference heading which is a time function of the heading, a movement control unit that controls the ship by distance control that makes the position of the ship follow the reference distance and route control that makes the position of the ship follow the trajectory and the heading of the ship follow the reference heading, a holding control unit that controls the ship to maintain its position, and a switching unit that switches from control by the movement control unit to control by the holding control unit when the intersection of the trajectory and a line extending from the position of the ship in the sway direction of the ship reaches the destination. Effect of the Invention

[0006] According to the present invention, a ship can be automatically docked and undocked. [Brief description of the drawings]

[0007] [Figure 1] 1 is a block diagram showing an overall configuration of a system including a marine automatic steering device. [Diagram 2] FIG. 1 is a diagram showing the configuration of a planned route. [Diagram 3] FIG. 1 is a diagram illustrating a classification of control systems. [Figure 4] FIG. [Diagram 5] FIG. 13 is a diagram showing a time series of reference orientations. [Figure 6] FIG. 13 is a diagram showing a reference velocity. [Figure 7] FIG. 2 is a diagram showing a planned route and a reference trajectory. [Figure 8] 2 shows a control object including a hull model and a drive machine model. [Figure 9] FIG. 13 is a diagram showing ship speed characteristics of a hull parameter Tr. [Figure 10] FIG. 13 is a diagram showing errors in a moving mode. [Figure 11] FIG. 13 illustrates an error in the hold mode. [Figure 12] FIG. 2 is a diagram showing a basic configuration of a control system. [Figure 13] FIG. 2 is a diagram illustrating a configuration of a control unit. [Figure 14] FIG. 2 is a diagram showing the configuration of a control system using a movement control unit. [Figure 15] FIG. 2 is a diagram showing a configuration of a control system using a holding control unit. [Figure 16] FIG. 13 is a diagram showing the planned route and ship position track when the tidal current is zero. [Figure 17] FIG. 13 is a diagram showing the planned route and ship position track when there is a tidal current. [Figure 18] FIG. 13 is a diagram showing the response of the ship motion. [Figure 19] FIG. 13 illustrates an error response. [Figure 20] FIG. 13 is a diagram showing a response to a command. [Figure 21] FIG. 11 is a diagram showing the response of the drive motor output. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0009] (1) Configuration of automatic steering system for ships First, a system including a marine automatic steering device according to this embodiment will be described below. Fig. 1 is a block diagram of the overall configuration of a system including a marine automatic steering device.

[0010] As shown in Fig. 1, a marine vessel automatic steering device 1 in this embodiment controls a vessel having a hull 2 ​​equipped with a propulsion drive unit 3 and sensors 4. In this embodiment, the propulsion drive unit 3 is a drive unit capable of controlling the speed in the surge direction and sway direction, and the angular velocity around the yaw, and in this embodiment, is configured as an azimuth thruster provided at the bow and stern of the hull 2.

[0011] The sensors 4 include a gyrocompass that detects the bow direction of the hull 2, a speedometer that detects the speed of the hull 2 ​​through the water, and a GNSS sensor that detects the hull position from a global navigation satellite system (GNSS) such as a GPS. Note that the sensors 4 may include any sensor that can detect the bow direction and the hull position.

[0012] The marine vessel automatic steering device 1 includes a reference trajectory generating unit 11 and a control unit 12. The reference trajectory generating unit 11 generates a reference trajectory based on the planned route output by the trajectory planning unit 5. The control unit 12 outputs commands to the propulsion drive unit 3 based on the bow heading and hull position detected by the sensors 4 to control the hull speed and angular velocity so that the hull 2 ​​follows the reference trajectory generated by the reference trajectory generating unit 11.

[0013] (2.2 Berthing and Unberthing Specifications) (2.2.1 Planned Route) The planned route will be explained below. Figure 2 is a diagram showing the configuration of the planned route.

[0014] The planned route includes the starting point, the destination point, the ship speed and the turning conditions, and is composed of a combination of straight lines and arcs, as shown in Figure 2. In Figure 2, O-XY is the Earth fixed coordinate system, ψ plan is the planned heading, point A is the starting point, and point B is the destination point. Also, points C, S, and F are the center point, start point, and end point of the turn, respectively, ρ is the turning radius, ψ set is the turning angle. Point D is the starting point of the ship's speed decelerating, and point E is the starting point of the course change.

[0015] On the planned route, the ship's forward speed is accelerated from point A, passes through a constant speed, and is decelerated from point D to reach destination point B. Also, the ship starts changing course from point E, which is located further forward than point S, to put the ship on the turning course.

[0016] (2.2.2 Overall Operation) The overall operation of the marine automatic steering device will now be briefly described.

[0017] The marine vessel automatic steering device 1 first rotates the heading ψ at the starting point A to a planned heading ψ plan After converging to the starting point A, the vessel position is moved from the starting point A to the destination point B and stopped there. Furthermore, if the vessel position after stopping has an error with respect to the destination point B, the vessel automatic steering device 1 moves the vessel position to the destination point B by path sequence control and stops there.

[0018] The path sequence control is a control that makes the ship's positions x, y and orientation ψ in the surge and sway directions follow reference signals, which are time-series signals of the reference position and orientation in the surge and sway directions, respectively, and each reference signal has a different timing, and is preferably generated so as not to overlap in time with other reference signals. The surge direction control, sway direction control, and orientation control in the path sequence control are state feedback controls based on the surge model, sway model, and yaw model of the ship model, respectively. For details of the path sequence control, please refer to Non-Patent Document 2.

[0019] Of these operations, the control for moving the hull position from starting point A to destination point B will be described below as hull position control.

[0020] (2.3 Ship position control) The vessel position control will be described with reference to FIG. 3, which shows the classification of control systems.

[0021] The hull position control includes a move mode and a hold mode. In the move mode, the hull position is moved to the destination point B by following a reference trajectory. However, the hull position does not always coincide with the destination point B. In the hold mode, the hull position is held at the terminal point B' located near the destination point B, i.e., at the destination point B' by the move mode having an error with respect to the destination point B. When the hull position is held at the destination point B, a transient phenomenon occurs due to the initial response (see non-patent document 2). To reduce this transient phenomenon, in the hold mode, the hull position is held at the terminal point B'.

[0022] (2.3.1 Reference orbit) The reference trajectory is composed of positions and times that satisfy the trajectory plan, and is used in the movement mode. The control unit 12 determines the hull position along the reference trajectory using point H, which is the intersection point between the reference trajectory and a line pointing in the sway direction from the hull position, as the basis for the reference trajectory. For example, the control unit 12 starts changing course when point H coincides with point E.

[0023] (2.3.2 Overview of the control system) The control system will be outlined below with reference to Fig. 3, which shows the classification of control systems.

[0024] The control unit 12 has a control system for each of the moving mode and the holding mode. In the moving mode, the control unit 12 makes the hull position follow the position corresponding to the time set in the reference trajectory, and in the holding mode, makes the hull position hold at the end point B' near the arrival point B.

[0025] In Fig. 3, DC indicates distance control, TC indicates course control, and DP indicates course keeping control. Course keeping control includes static determination control and the above-mentioned route sequence control. Static determination control is a control for converging the vessel position P to the terminal point B'.

[0026] In the movement mode, the control unit 12 obtains the error between the reference trajectory and the hull position from point H, and corrects this error by distance control and route control. In the holding mode, the control unit 12 corrects the error between the terminal point B' and the hull position by static determination control, and moves the hull position from the terminal point B' to the destination point B by path sequence control. Note that the movement from the terminal point B' to the destination point B may be controlled by a control law other than the path sequence control.

[0027] (3 reference orbits) The reference trajectory will now be described. The reference trajectory is generated by the reference trajectory generating unit 11 and is configured based on the planned route. The control unit 12 makes the ship position follow the reference trajectory. In order to reduce control errors, the reference trajectory takes measures against the following factors:

[0028] 1. Transient phenomena caused by changes in ship speed 2. Transient phenomena caused by angular velocity during turning 3. Measures against 1 and 2 above and route errors caused by ship motion

[0029] These measures are explained below. For the sake of explanation, they will be described in the order of 2, 1, and 3.

[0030] (3.1 Reference direction) The reference orientation in the reference trajectory will now be described. Fig. 4 is a diagram showing the reference angular velocity. Fig. 5 is a diagram showing the time series of the reference orientation.

[0031] The trajectory plan of the reference heading is set to satisfy the turning conditions of the planned route. The turning conditions are radius ρ, ship speed u R , course change amount ψ set , angular velocity r=u R ÷ρ, acceleration time T a , constant velocity time T v , deceleration time T d Here, the subscript R means the reference signal. To avoid complicating the equation, the sign of the course change is ψ set> 0. The reference heading is set so that the change in course begins when point H passes point E, as shown in Figure 4.

[0032] Reference direction ψ R The time function of is as follows, as shown in Figure 5.

[0033]

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[0034] The orbit coefficients and initial values ​​of the above equation are as follows:

[0035]

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[0036] Course change amount ψ set Since is the sum of the course deviations in each mode, we obtain the following equation.

[0037]

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[0038] The differential value of the reference direction is calculated at the start and end of each mode.

[0039]

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[0040] (3.2 Reference distance) The reference distance in the reference trajectory will now be described with reference to Fig. 6, which is a diagram showing the reference velocity.

[0041] Reference distance d R is determined as the surge direction distance from the starting point A to the destination point B. The trajectory plan of the reference distance is set to satisfy the ship speed condition of the planned route. The ship speed condition determines the acceleration mode and deceleration mode. As shown in Figure 6, the acceleration mode is set from the starting point A to the acceleration time T a u The deceleration mode is from point D to deceleration time T d u The constant velocity mode is set between the acceleration mode and the deceleration mode, and the acceleration time from the starting point A to the acceleration time T a u The time is set to the time from when the reference heading has passed until the ship passes point D. The course change operation using the reference heading is performed in constant speed mode. Therefore, the trajectory plan for the reference distance can be configured in the same way as for the reference heading. The control system is less susceptible to transient phenomena caused by the differential value of the reference distance, just like the reference heading.

[0042] Reference distance d R In the above formulas (1) to (3) described in (3.1 Reference Orientation),

[0043]

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[0044]

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[0045] Distance d to point D AD is expressed as follows:

[0046]

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[0047]

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[0048] (3.3 Reach fix) The reach correction will now be described.

[0049] The reference trajectory is affected by the acceleration and deceleration times of the reference heading and reference distance by taking measures against transient phenomena caused by changes in ship speed and angular velocity during turns.

[0050] The influence of the reference direction is shown. The course change time is calculated from equation (9) as

[0051]

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[0052]

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[0053]

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[0054] Figure 7 shows the planned route and the reference trajectory. In Figure 7, the route after points F and R is omitted, and the planned route is assumed to be a right turn northward from the origin O. For the sake of simplicity, the planned direction ψ of the straight route is shown in Figure 7. plan Rotate to face north.

[0055] The reference trajectory is calculated from the reference speed and the reference heading.

[0056]

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[0057]

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[0058] Route error d r In Figure 7, the tangent intercept x at the turning end points R and F R ,x F If we calculate from

[0059]

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[0060] Therefore, the route error d r The corrective measure is to change the starting point of the change in course from the starting point S of the trajectory plan to d r The movement to point E is called the reach correction.

[0061] (4. Hull Control) A control system for tracking the hull to the reference trajectory and the initial hull position value will be described.

[0062] (4.1 Control Object) The controlled object will be described. FIG. 8 shows the controlled object including the hull model and the driving machine model. FIG. 9 shows the hull parameter T r FIG.

[0063] The controlled object consists of a hull model and a drive machine model, as shown in Fig. 8.

[0064] (4.1.1 Hull model) The hull model is indexed by the surge direction. u , sway direction is indexed v , yaw around index r and

[0065]

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[0066]

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[0067] FIG. 9 shows the ship speed (water speed) characteristics of the hull parameters. In FIG. 9, T r Only the other variables {K r ,K u ,T u ,K v ,T v} is also related to the ship's speed. r The low speed characteristics in are assumed to be dominated by inertia terms, ignoring propulsive resistance. From Figure 9, the hull parameters have the following ship speed characteristics:

[0068] 1. The holding mode region is |u|≦2kn and is constant. 2. The travel mode range is u>2kn and is proportional to the ship speed.

[0069] (4.1.2 Driving Machine Model) The driving machine model will now be described.

[0070] The azimuth thruster model of the driving machine (hereafter referred to as ATM) controls the thrust vector by the propeller rotation speed (not reversed) and its direction. The direction angle (opening) and rotation speed are limited. In Figure 8, the rotation speed λ and thrust F of the two ATMs are

[0071]

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[0072]

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[0073]

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[0074] On the other hand, if the ATM output γ is replaced by the command amount,

[0075]

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[0076] (4.2 Definition of Error) (4.2.1 Movement Mode) The error in the moving mode will now be described with reference to Fig. 10, which is a diagram showing the error in the moving mode.

[0077] The error in the movement mode is set for both the straight route and the circular route, as shown in FIG.

[0078] Orientation error ψ e teeth,

[0079]

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[0080] Route error y e is the distance between the ship position P and point H.

[0081]

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[0082]

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[0083] distance error d e depends on the distance to the trajectory plan position.

[0084]

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[0085]

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[0086]

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[0087] (4.2.2 Retention Mode) The error in the hold mode will now be described. Fig. 11 is a diagram showing the error in the hold mode. Note that Fig. 11 shows a state in which the mode has been switched from the move mode to the hold mode.

[0088] The switch from the moving mode to the holding mode shown in Fig. 11 is performed when point H based on the hull position P reaches the destination point B. At this time, the destination point of the holding mode is changed from B to the terminal point B'. Therefore, the terminal point B' is the terminal position of the hull position P in the moving mode. This replacement of the destination point B with the terminal point B' prevents transient phenomena due to the initial value of the holding mode (see Non-Patent Document 2).

[0089] When switching from the moving mode to the holding mode, the position and heading of the vessel position P are replaced with the terminal point B'. That is, the following equation is obtained.

[0090]

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[0091] Orientation error ψ e teeth,

[0092]

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[0093] position error x e ,y e is expressed in ship coordinates and is given by the following equation.

[0094]

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[0095]

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[0096] (4.3 Control System) The control system will now be described. Fig. 12 is a diagram showing the basic configuration of the control system. Fig. 13 is a diagram showing the configuration of the control unit. Figs. 14 and 15 are diagrams showing the configurations of the control system using a movement control unit and a holding control unit, respectively.

[0097] As mentioned above, the control system consists of distance control (DC), course control (TC), and course keeping control (DP) (see Fig. 3). The basic configuration of the control system is as shown in Fig. 12, where an error is input, a command is output, and the control gain is updated using the hull parameters corresponding to the water speed.

[0098] 13, the control unit 12 includes a movement control unit 121 that performs control in the movement mode, a hold control unit 122 that performs control in the hold mode, and a switching unit 123. The switching unit 123 detects the formula (48) from the ship's position and switches the control subject between the movement control unit 121 and the hold control unit 122, thereby switching the control system from the movement mode to the hold mode.

[0099] In Fig. 14 and Fig. 15, C(s) indicates the controller. d is distance control, subscript t is the route error control, and the subscript h indicates azimuth control. In FIG. x , subscript y , subscript ψ indicate hull position holding control, which correspond to surge, sway, and yaw, respectively. As shown in Fig. 14, the movement control unit 121 has a distance controller, a route controller, and a heading controller. Also, as shown in Fig. 15, the holding control unit 122 has hull position holding controllers corresponding to surge, sway, and yaw, respectively. Since the controllers other than the route controller have the same configuration, they function as a distance controller, heading controller, and hull position holding controller by being given hull parameters and design parameters corresponding to these controllers.

[0100] (4.3.1 Route Control) Route control will now be explained.

[0101] Route control is route error y e Converging to zero, it consists of heading control and route error correction. For details of route control, please refer to Non-Patent Document 3. The heading control corrects the rudder angle offset. The route error control corrects the route error due to the tidal current component by adding an integral action.

[0102] The azimuth control is an estimator plus a state feedback gain, as follows:

[0103]

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[0104]

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[0105] The route error control is obtained by filtering the route error and multiplying it by the route gain, as follows:

[0106]

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[0107] The command given by route control is as follows:

[0108]

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[0109] (4.3.2 Distance control and vessel position keeping control) The distance control and the vessel position keeping control will now be described.

[0110] The distance control and the ship's position keeping control are both configured in the same way as the heading control. By inputting the hull parameters and design parameters of the distance control and the ship's position keeping control to equation (52), the control systems for the distance control and the ship's position keeping control can be obtained.

[0111] (5 Verification) The effectiveness of the marine automatic steering device according to this embodiment will be verified by simulation.

[0112] (5.1 Simulation Conditions) The simulation conditions will be described.

[0113] In the simulation, the calculation time is 25 minutes, the first half of which is controlled in moving mode, and the second half in holding mode, with the step time being 0.1 seconds. The disturbance is a tidal component of 1.0 kn, heading north. In addition, the hull parameters are constant values, not speed-dependent. The set values ​​for the planned route are shown below.

[0114]

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[0115]

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[0116] For the drive unit, the constant rotation speed is λ0 = 110 rpm and the angle limit is 45 deg.

[0117] The hull parameters and main design parameters are shown below.

[0118]

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[0119] Since the route error control does not include integral action, route error due to tidal components occurs. The scale transformation is γ r ′=0.2γ r The coefficient for converting the sway direction command speed into an angle is 45deg / 10kn. The reach amount is reach = 76.0m under the above conditions.

[0120] (5.2 Simulation Results) The simulation results will now be described. Figs. 16 to 21 all show the simulation results. Figs. 16 and 17 are diagrams showing the planned route and ship position track when there is no tidal current and when there is a tidal current, respectively. Fig. 18 is a diagram showing the response of ship motion. Fig. 19 is a diagram showing the response of error. Fig. 20 is a diagram showing the response of a command. Fig. 21 is a diagram showing the response of the drive motor output.

[0121] As shown in Fig. 16, the reach appears to be large during turning, but the course error converges to zero after turning. Of Figs. 16 to 21, only Fig. 16 shows the simulation results when there is no tidal current.

[0122] As shown in Figure 17, the route error is caused by the tide, but it converges to a constant value. The error between the end point B' and the destination point B is 25.5 m.

[0123] As shown in Figure 18, the surge speed u does not have enough time or distance to converge to the ground speed in the first half of the turn. The sway speed v generates an interference error with the yaw motion during the turn in the first half, but is stable. There is no problem with the yaw angular velocity r.

[0124] As shown in Figure 19, x e The convergence of y e and ψ e Worse than y e and ψ e teeth

[0125]

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[0126] As shown in FIG. 20, in the latter holding mode, the command has a bias to hold the vessel position at terminal point B'.

[0127] As shown in FIG. 21, no saturation limit occurs in the response of the driver output.

[0128] Therefore, it was confirmed that the control by the marine vessel automatic steering device 1 according to this embodiment operates appropriately.

[0129] The embodiments of the present invention are presented as examples and are not intended to limit the scope of the invention. This novel embodiment can be implemented in various other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. This embodiment and its modifications are included in the scope and spirit of the invention, and are included in the scope of the invention and its equivalents described in the claims. [Explanation of symbols]

[0130] 1. Automatic steering system for ships 2. Hull 3 Propulsion drive 4 Sensors 11 Reference trajectory generator 12 Control section 121 Movement control section 122 Retention control section 123 Switching section

Claims

1. An automatic ship steering device for controlling a ship having a propulsion drive device capable of controlling a speed in a surge direction and a sway direction and an angular speed around a yaw, and a sensor for detecting a bow heading and a ship position, a reference trajectory generating unit that generates a reference trajectory including a trajectory from a starting point to a destination point, a reference distance that is a time function of a surge direction distance from the starting point to the destination point, and a reference direction that is a time function of a direction; a movement control unit that controls the ship by a distance control that causes the position of the ship to follow the reference distance, and a route control that causes the position of the ship to follow the trajectory and the orientation of the ship to follow the reference orientation; a holding control unit that controls the vessel to hold a position of the vessel; a switching unit that switches control from the movement control unit to control by the holding control unit when an intersection of a line extending from the position of the ship in the sway direction of the ship and the trajectory reaches the destination point; An automatic steering device for a ship.

2. The automatic vessel steering device according to claim 1, characterized in that, when the holding position of the vessel is not the destination point, the holding control unit controls the vessel so as to reduce an error between the position of the vessel and the destination point.

3. the movement control unit and the hold control unit each update a control gain based on a hull parameter corresponding to a water speed of the vessel, The automatic steering device for a vessel according to claim 1 or claim 2, characterized in that the hull parameter is proportional to a water speed at a water speed greater than a predetermined water speed threshold under control by the movement control unit, and is constant at a water speed that is equal to or less than the water speed threshold under control by the holding control unit.

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