WO2023089843A1

WO2023089843A1 - Automatic steering device for vessels

Info

Publication number: WO2023089843A1
Application number: PCT/JP2022/014318
Authority: WO
Inventors: 冬希羽根
Original assignee: 東京計器株式会社
Priority date: 2021-11-18
Filing date: 2022-03-25
Publication date: 2023-05-25
Also published as: JP2023074951A

Abstract

The present invention is characterized by comprising: a reference trajectory generation unit that generates, on the basis of a planned sea route, a reference trajectory including a trajectory from a departure point to an arrival point, a reference distance that is a time function of surge direction distance from the departure point to the arrival point, and a reference azimuth that is a time function of an azimuth; a movement control unit that controls a vessel on the basis of distance control for causing the position of the vessel to conform to the reference distance, and sea route control for causing the position of the vessel to conform to the trajectory and also for causing the azimuth of the vessel to conform to the reference azimuth; a holding control unit that controls the vessel so as to hold the position of the vessel; and a switching unit that, if the intersection of the trajectory and an orthogonal line that passes through the position of the vessel and is orthogonal to the trajectory reaches the arrival point, switches from control by the movement control unit to control by the holding control unit. The present invention is also characterized in that the distance control involves: feed-forward control for causing a vessel distance that is a distance from a departure position to the intersection to conform to the reference distance; and feed-back control for causing a distance error between the reference distance and the vessel distance to converge at zero.

Description

Marine autopilot

The present invention relates to technology for automatically steering ships.

In recent years, there has been active development of autonomy for mobile objects that move on land, sea, air, and even under the sea. Autonomous mobile bodies are used in a wide variety of ways, including transportation, investigation, search, and rescue. A familiar example of an autonomous mobile object is a robot vacuum cleaner that autonomously moves and cleans a room. Such an autonomous mobile body is managed and controlled by a computer in terms of trajectory planning and execution, attitude, speed, position, etc., by giving a commander a purpose and a target location.

Autonomous ships, which are autonomous ships, are also controlled in the same way as the moving bodies described above. Technologies related to autonomous ships are roughly classified into motion control of berthing/berthing, tracking, and avoidance. As a control technology for an autonomous ship, there is known a technology for controlling a ship to be controlled so that it moves from a stopped state at a departure point, turns on the way, and stops at a destination. It is also important that such technology be versatile enough to be applied to many vessels.

As is well known, compared to other vessels, ships have a large inertial force and weak braking force, and are characterized by extremely small resistance from fluids at low speeds. Therefore, hull positioning control (SPC: Ship Positioning Control) can be cited as one of the core elements of an autonomous ship. SPC plans a reference trajectory that realizes a given planned route, sailing speed and turning conditions, and makes the hull position follow it, and is an extension of the hull positioning system (DPS: Dynamic Positioning System).

Without using DPS, it is difficult to stop the ship so that any heading and hull position are maintained. The technology described in Non-Patent Document 1 implements ship stop control using DPS. In addition, according to the technique described in Non-Patent Document 2 using SPC, since the speed of the ship follows the deceleration of the reference speed with a delay, there arises a problem that the ship passes the destination.

The problem to be solved by the present invention is to provide a technique that allows a ship to be brought closer to its destination and stopped.

A marine autopilot system according to an embodiment includes a propulsion drive device capable of controlling the velocities in the surge direction and the sway direction and the angular velocity around the yaw, and a sensor for detecting the heading and the position of the hull. An automatic steering device, based on a planned route, a trajectory from a starting point to a destination point, a reference distance that is a time function of the surge direction distance from the starting point to the destination point, and a time function of the heading a reference trajectory generator for generating a reference trajectory including a reference bearing; distance control for causing the position of the ship to follow the reference distance; a movement control unit that controls the ship, a holding control unit that controls the ship to hold the position of the ship, and an orthogonal line that passes through the position of the ship and is orthogonal to the trajectory and a switching unit for switching from control by the movement control unit to control by the holding control unit when the intersection of the trajectory and the trajectory reaches the arrival point, wherein the distance control is a distance from the starting position to the intersection and feedforward control for causing the hull distance to follow the reference distance, and feedback control for converging the distance error between the reference distance and the hull distance to zero.

According to the present invention, the ship can be brought closer to the destination and stopped.

1 is a block diagram showing the overall configuration of a system including a marine automatic steering device; FIG. It is a figure which shows the form of a planned route. FIG. 2 is a diagram showing classification of control systems in hull positioning control; FIG. 3 is a diagram showing a controlled object including a hull model and a drive machine model; FIG. 4 is a diagram showing ship speed characteristics of a hull parameter _Tr ; It is a figure which shows the structure of a control part. FIG. 10 is a diagram showing errors in movement mode; FIG. 10 is a diagram showing errors in hold mode; It is a figure which shows the structure of the control system by a distance control part. FIG. 10 is a diagram showing the time series of the reference distance d _R and the feedforward rotation λ _FF ; FIG. 10 is a diagram showing ship position estimation during route turning; It is a figure which shows the calculation result of a reference position and a route position. FIG. 4 is a diagram showing a planned route and a ship's position track when the tidal current is zero; FIG. 4 is a diagram showing a planned route and a ship's position track when there is a tidal current; FIG. 4 is a diagram showing the response of ship motion; FIG. 10 is a diagram showing the error response; FIG. 10 is a diagram showing a command response; FIG. 4 is a diagram showing the response of the driver output;

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

(1 Hull Positioning Control)
(1.1 Configuration of marine automatic steering system)
A system including a marine autopilot according to this embodiment will be described. FIG. 1 is a block diagram showing the overall configuration of a system including a marine autopilot.

As shown in FIG. 1, a marine autopilot system 1 according to the present embodiment controls a marine vessel having a hull 2 equipped with a propulsion drive device 3 and sensors 4 . In this embodiment, the propulsion drive device 3 is a drive device capable of controlling the velocities in the surge direction and the sway direction and the angular velocity around the yaw. Configured as a thruster.

The sensors 4 include a gyrocompass that detects the heading of the hull 2, a speedometer that detects the water speed of the hull 2, and a GNSS sensor that detects the hull position from a satellite positioning system (GNSS) such as GPS. It should be noted that the sensors 4 may include sensors capable of detecting the ship's heading and hull position.

The marine automatic steering device 1 includes a reference trajectory generator 11 and a controller 12 . The reference trajectory generator 11 generates a reference trajectory based on the planned route output by the trajectory planer 5 . The control unit 12 outputs a command to the propulsion drive unit 3 based on the heading and hull position detected by the sensors 4 so that the hull 2 follows the reference trajectory generated by the reference trajectory generation unit 11. Controls hull speed and angular velocity.

(1.2 Planned route)
Explain the planned route. FIG. 2 is a diagram showing the form of the planned route.

As shown in FIG. 2, the planned route includes a starting point, a destination point, forward speed and turning conditions, and is composed of a combination of straight lines and circular arcs. In FIG. 2, O-XY is the earth-fixed coordinate, ψ _plan is the planned direction, point A is the starting point, and point B is the reaching point. Points C, S, and F are the turning center point, starting point, and ending point, respectively, ρ _set is the turning radius, and ψ _set is the turning angle.

(1.3 Hull Positioning Control)
Hull positioning control will be described. FIG. 3 is a diagram showing the classification of control systems in hull positioning control.

The hull positioning control by the control unit 12 of the marine autopilot system 1 accelerates the forward speed from point A, turns at a constant speed, and then decelerates to reach the destination point B on the planned route shown in FIG. Control the vessel to maintain position.

The hull positioning control has two control modes, a moving mode and a hovering mode, as shown in FIG. The control unit 12 executes distance control DC and route control TC in the movement mode, and hull position maintenance control DP including static stabilization control and route sequence control (see Non-Patent Document 3) in the hold mode.

The reference trajectory is generated by the reference trajectory generation unit 11 based on the planned route, and is composed of the azimuth/position and time that satisfy the trajectory plan. Specifically, the reference trajectory includes a trajectory from a starting point to a destination point, a reference distance that is a time function of the surge direction distance from the starting point to the destination point, and a reference azimuth that is a time function of the azimuth. include. The control unit 12 determines the hull position along the reference trajectory using the point H, which is the intersection of the reference trajectory and the line passing through the hull position and orthogonal to the reference trajectory, as the reference of the reference trajectory.

The control unit 12 causes the heading and the hull position to follow the heading and position associated with the time set in the reference orbit according to the movement mode, and when the point H reaches the point B, the control unit 12 Switch the mode from move mode to hold mode. Furthermore, in the holding mode, the control unit 12 corrects the error between the hull position and the terminal point B′ in the control by the movement mode, which is located near the point B, by static control, so that the terminal point B′ and the arrival point B are corrected. are different, the hull position is moved from the terminal point B' to the arrival point B by path sequence control. Note that the movement from the terminal point B' to the destination point B may be controlled by other control rules than the route order control. According to Non-Patent Document 3, the magnitude of the holding response transient is proportional to the distance between the end point B' and the point B. In order to reduce this phenomenon, in the static control, the reaching point is replaced with the terminal point B' instead of the point B.

(2 Control object)
A controlled object will be explained. FIG. 4 is a diagram showing a controlled object including a hull model and a drive machine model. The object to be controlled is, as shown in FIG. 4, a double-headed ship composed of a hull model and a drive machine model.

(2.1 Hull model)
The hull model will be explained. The hull model is represented by the subscript _u for the surge direction, the subscript _v for the sway direction, and the subscript _r for around the yaw.

and where s is the Laplace operator, P(s) is the transfer function, U(s) is the surge velocity, V(s) is the sway velocity, and R(s) is the yaw angular velocity. Λu(s), Θv(s), and Θr(s) are control inputs (instruction amounts), which are the propeller rotation speed and two thrust angles, respectively. The transfer function of the hull model is

is. Here, both T and K are hull parameters, a time constant and a gain, respectively.

FIG. 5 shows ship speed (water speed) characteristics of the hull parameters. In FIG. 5, only _Tr is shown among the hull parameters, but other variables { _Kr , _Ku , _Tu , _Kv , _Tv } are also related to ship speed. The low-speed characteristics in _Tr are assumed to be the inertia term, ignoring propulsion resistance. From FIG. 5, the hull parameters have the following ship speed characteristics.

1. The holding mode region is |u|≦2kn and is constant.
2. The movement mode range is u>2kn and is proportional to ship speed.

(2.2 Drive model)
The drive machine model will be explained. The azimuth thruster model of the driver (hereafter ATM) controls the thrust vector by its propeller speed (not reversed) and its direction. There are restrictions on the number of revolutions and the thrust angle. In Fig. 4, the rotational speed λ and the water thrust F of the two ATMs are

become. where the subscripts _f 1 and _a denote fore and aft ATMs, respectively, and λ ₀ is the constant rotation speed.

　The relationship between the command amount and the thrust angle is

become. where θ _f and θ _a are both the angles of the thrust direction of the ATM with respect to the baseline of the ship. At this time, the equivalent amount of the generated force is

become.

Therefore, the ATM output is obtained by multiplying the above formula by the scale factor,

become. Here, c _θ ^v is a coefficient for converting units from velocity to thrust angle.

(3 control system)
(3.1 Configuration of control unit)
The configuration of the control unit will be described. FIG. 6 is a diagram showing the configuration of the control unit.

As shown in FIG. 6, the control unit 12 includes a movement control unit 121 that performs distance control DC and route control TC in the movement mode, a holding control unit 122 that performs hull position holding control DP in the holding mode, and a switching unit 123. Prepare. The switching unit 123 switches the control system from the moving mode to the holding mode by switching the control subject from the moving control unit 121 to the holding control unit 122 when the point H based on the hull position reaches the point B.
(3.2 Definition of error)
(3.2.1 Movement Mode)
As shown in FIG. 7, the movement mode error is set from the point P of the hull position, the point H of the drooping foot, and the point R of the reference position. The heading error ψ _e , course error y _e , and distance error d _e are

become. where ψ is the heading, _ψR is the reference bearing, and _ye is the distance between points P and H. again,

represents the signed distance between two points, P, H are the x, y coordinates of point P and point H, respectively, d _R is the reference distance from the starting point to point R, and d _H is the starting is the hull distance from the ground to point H. See Non-Patent Document 2 for error calculation.

(3.2.2 Hold mode)
FIG. 8 shows the state after switching from the move mode to the hold mode. As described above, the control mode is switched when the point H reaches the reaching point B. At this time, the reaching point is replaced from the point B to the point B'. Specifically, this replacement is as shown in the following formula.

where B', ψ _B' are the final x, y coordinates and orientation, respectively, in the move mode.

The azimuth error ψ _e ^k in the holding mode and the position errors x _e ^k and y _e ^k in the hull coordinates indicated by subscript ^K are

become. where Ω _B ^E (ψ) is a matrix that transforms from earth coordinates (subscript ^E ) to hull coordinates (subscript _B ),

is.

(3.3 Distance control)
Distance control DC converges the distance error to zero by trajectory tracking control. Trajectory tracking control is composed of a reference distance and a two-degree-of-freedom control system including feedforward control and feedback control. Feedforward control causes the hull distance to follow the reference distance, and feedback control forms a closed loop system with the controlled object to converge the distance error to zero.

(3.3.1 Reference distance and feedforward control)
FIG. 9 shows the configuration of the distance control DC by the distance control section. In FIG. 9, RG is a reference distance generator, s is a Laplacian operator, C _d ^FF (s) is a feedforward controller, C _d ^FB (s) is a feedback controller, P _x (s)=P _u (s )·s ⁻¹ is the range hull model.

The reference distance generator outputs a reference distance D _R (s) from the input position condition, and the feedforward controller outputs a feedforward rotation Λ _FF (s) from the reference distance D _R (s). The feedback controller outputs the feedback rotation Λ _FB (s) from the distance error D _e (s), stabilizes the closed loop of the distance control DC, and removes the disturbance D _D (s). The commanded propeller rotation Λ _u (s) of the control amount is given by the following equation.

Using the trajectory tracking control, the transfer characteristic of the distance error D _e (s) is

become. From the above equation, the closed-loop stability and disturbance rejection depend on the feedback controller C _d ^FB (s), and the followability depends on the feedforward controller C _d ^FF (s).

The feedforward rotation Λ _FF (s) becomes:

Here, the feedforward controller corresponds to the inverse characteristic of the range hull model.

is. Therefore, the hull distance is

, matching the reference distance.

As shown in FIG. 10, the reference distance d _R and the feedforward rotation λ _FF are defined by the distance trajectory condition

satisfy. Here, the suffix _set represents a set value. The relationship between _dR and _λFF is

become. where a is the coefficient and _td is the reference distance time. For details of the above formula, refer to Non-Patent Document 4.

(3.3.2 Feedback control)
The feedback controller consists of an estimator and state feedback,

become. For details of C _d ^FB (s), see Non-Patent Document 2.

(3.4 Route control)
The course control TC converges the course error _ye to zero by bearing control and course error control. The commanded thrust angle _θr for route control is given by the following equation.

Here, subscript _h and subscript _t represent heading control and course error control, respectively.

(3.4.1 Direction control)
The azimuth control HC converges the azimuth error ψe to zero, has the functions of holding the azimuth and changing course, and has the same configuration as the distance control DC. Therefore, the azimuth control HC is obtained by replacing the distance in the distance control DC with the azimuth. The commanded thrust angle Θ _h (s) of the control amount by the azimuth control HC is

become. where Θ _FF (s) is the feedforward thrust angle, C _h ^FF (s)=(P _ψ (s)) ⁻¹ is the feedforward controller, C _h ^FB (s) is the feedback controller, P _ψ ( s)=P _r (s)·s ⁻¹ is the azimuth hull model.

The reference azimuth ψ _R and the feedforward thrust angle θ _FF are the turning conditions of the azimuth.

satisfy. The relationship between ψ _R and θ _FF is

become. where b is the coefficient and t _ψ is the reference azimuth time.

(3.4.2 Course error control)
The route error control constitutes a closed loop system with the sway hull motion, converges the route error to zero, and corrects the error due to the tidal current component. The course error controller C _t (s) is the filtered course error Y _e (s) multiplied by the control gain,

become. where T _y is the filter time constant, f _y is the route gain, and f _i is the integral gain. The action of the integrator compensates for the effects of disturbance components that move the hull position. Please refer to Non-Patent Document 5 for the setting of the control gain in the above equation.

(3.5 Estimation of reach amount)
The reach amount estimation executed by the reference trajectory generator 11 determines the position at which to start changing course in a course turn, governs the course error during the turn, and is called WOP (Wheel Over Point). The position of the WOP is before the point S in FIG. 2 by the reach amount. The amount of reach is calculated from the reference position and route position. The reference positions x _R and y _R are

Ask from where ψ _R is the reference bearing and ρ _set is the turning radius.

As shown in Fig. 11, the route position is obtained from the trajectory plan, the drive machine, and the model of the hull motion. When the feedforward command set in the trajectory plan is input to the drive machine

become. Here, the feedforward rotation λ _FF keeps the boat speed constant (set value u _set ).

The hull positions x, y are calculated using the hull motions r, u, v

Ask from

Fig. 12 shows the results of obtaining the reference position and route position. In FIG. 12, the markers on the line indicate the reference azimuth ψ _R in increments of 10 degrees, and the values described later in section 4.1 are used for the hull parameters of the movement mode and the turning conditions.

The reach amount reach is obtained from the positional relationship between the reference position corresponding to ψ _R =90 degrees in FIG. 12 and the maximum value of the route position.

become. However, reach depends on the hull motion model and calculation conditions.

(3.6 Control by holding mode)
In the hold mode, the control unit 12 performs static control and route sequence control by operation management. Static control and path sequence control are performed by three controllers, which ensure closed-loop stability and disturbance rejection with surge, sway, and yaw hull motions, respectively, and distance control DC It has the same configuration as the feedback controller C _d ^FB (s). Therefore, each of the three controllers replaces the distance in the feedback controller C _d ^FB (s) with surge, sway, and yaw. Each hull parameter uses a very slow response for holding mode. The three controllers are each:

become. where the subscript ^k represents the hold mode, and C _x (s), _Cy (s), and C _ψ (s) are the surge, sway, and yaw controllers, respectively.

(4 Verification)
The effectiveness of the marine automatic steering system according to this embodiment is verified by simulation.

(4.1 Simulation conditions)
Simulation conditions will be described.

In the simulation, the calculation time is 30 minutes, the first half (18.3 minutes) is controlled by the movement mode, the second half (11.7 minutes) is controlled by the hold mode, and the step time is 0.1 s. The disturbance component in the simulation is assumed to be a tidal current component with a northward direction of 1.0 kn and an azimuth offset of 0.3 deg/s.

The hull parameters in the simulation are shown in the table below.

In this table, _T3 is the hull model

and is equivalent to the rudder sensitivity time constant.

Note that in equations (4) to (6), the coefficient corresponding to T ₃ is omitted because T ₃ <<|T|. _T3 is used to generate reference signals D _R (s) and Ψ _R (s).

The set values for the planned route in the simulation are shown below.

Also, the turning angular velocity set value r _set =u _set ÷ρ _set =0.172 rad/s is used.

The constant rotation speed of the driving machine in the simulation is λ ₀ =110 rpm, and the angle limit is 45 degrees.

In the simulation, the main control parameters were common to the moving mode and the holding mode, and the proportional gain was K _p =1, the damping coefficient was ζ=1÷√2, and the damping coefficient of the integral gain was ζ _i =0.9. be. The coefficient for angular conversion of the sway direction command speed is c _θ ^v =45 deg/10 kn. Expression (41) is used for the reach amount.

(4.2 Simulation results)
Simulation results will be explained. 13 to 18 all show simulation results. FIG. 13 and FIG. 14 are diagrams showing the planned route and the ship's position track when the tidal current is zero and when there is a tidal current, respectively. FIG. 15 is a diagram showing the response of ship motion. FIG. 16 shows the error response. FIG. 17 is a diagram showing a command response. FIG. 18 is a diagram showing the response of the driver output.

As shown in FIG. 13, point B′ is within a radius of 1 m from point B when there is no disturbance component. As shown in FIG. 14, when there is a disturbance component, the course error y _e is caused by the disturbance component, but the point B′ is within a radius of 10 m from the point B. Also, in the ship's position track in the moving mode up to point B', the distance error d _e is the same as in the case without the disturbance component, and the error due to the disturbance has been corrected. On the other hand, the route error _ye becomes larger than when there is no disturbance component, and it becomes difficult to correct the error as the boat speed decreases.

As shown in FIG. 15, the surge velocity u, sway velocity v, and yaw angular velocity r are biased under the influence of disturbance components.

As shown in FIG. 16, in the moving mode, x _e corresponding to the distance error d _e and the course error y _e converge to zero, and the heading error ψ _e has an oblique navigation angle. The skew angle fluctuates due to the term due to the tidal current component and the term due to the r and v generation due to the steering angle offset of the _r0 correction. The table below shows the fully statically settled case.

Fig. 17 shows the command response. FIG. 18 is the response of the driver output, with no saturation.

From the above simulation results, it was confirmed that the control by the marine autopilot system 1 according to the present embodiment was properly operated.

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 embodied in various other forms, and various omissions, replacements, and modifications can be made without departing from the scope of the invention. This embodiment and its modifications are included in the scope and gist of the invention, and are included in the scope of the invention described in the claims and its equivalents.

1 marine automatic steering device 2 hull 3 propulsion drive device 4 sensors 11 reference trajectory generation unit 12 control unit 121 movement control unit 122 holding control unit 123 switching unit

Claims

An autopilot for a marine vessel that controls a marine vessel comprising a propulsion drive device capable of controlling the velocities in the surge and sway directions and the angular velocity around the yaw;
Based on the planned route, a reference trajectory including a trajectory from a starting point to a destination point, a reference distance that is a time function of the surge direction distance from the starting point to the destination point, and a reference bearing that is a time function of the bearing a reference trajectory generator that generates
A movement control unit that controls the vessel by distance control that causes the position of the vessel to follow the reference distance, and route control that causes the position of the vessel to follow the trajectory and the azimuth of the vessel to follow the reference azimuth. and,
a holding control unit that controls the ship to hold the position of the ship;
a switching unit that switches from control by the movement control unit to control by the holding control unit when an intersection of the trajectory and an orthogonal line that passes through the position of the ship and is orthogonal to the trajectory reaches the arrival point;
The distance control includes feedforward control that causes the hull distance, which is the distance from the starting position to the intersection point, to follow the reference distance, and feedback control that causes the distance error between the reference distance and the hull distance to converge to zero. An automatic steering system for a ship, characterized by:
The reference trajectory generator, based on a positional relationship between a reference position based on the reference bearing and turning radius, and a route position based on the reference trajectory, a drive machine model of the propulsion drive device, and a hull model of the ship, 2. The automatic steering system for ships according to claim 1, wherein the amount of reach is calculated.
3. The marine automatic steering system according to claim 2, wherein the route position is calculated based on the drive machine model and the hull model to which the feedforward command by the feedforward control is input.
4. The controller for controlling the route filters the route error, which is the distance between the trajectory and the position of the ship in the orthogonal direction, and multiplies it by an integral gain. or the marine autopilot according to claim 1.
The controller has C t (s) as the controller, Ty as the filter time constant, f y as the route gain, and fi as the integral gain,

5. A marine autopilot system according to claim 4, characterized in that it is represented by .