METHOD FOR CONTROLLING A TOWING TRAIN

Abstract

A method for controlling a towing train including a ship and at least one tug acting on the ship, including the steps of: providing a data model, which includes fixed data of the ship and of the at least one tug as well as variable environmental data; determining the current course, the thrust vector, and the inertial force of the ship and specifying a desired travel direction of the ship with subsequent calculation of the correction force vector and correction torque required to achieve the desired travel direction; calculating the required positions, orientations, and drive settings of the at least one acting tug using an algorithm that accesses the data model and generating control commands for the at least one tug such that the sum of all the force vectors and torques of the at least one acting tug corresponds to the required correction force vector and correction torque; transmitting the generated control commands to at least one acting tug and monitoring the completion of the control commands; and conducting an evaluation of the produced correction force vector and correction torque after completion of the control commands and generating and storing correction values in the data model when deviations are detected between the produced correction force vector and the required correction force vector and/or between the produced correction torque and the required correction torque and then repeating certain steps.

Claims

1. A method for controlling a towing train including a ship (1) and at least one tug (2, 2.1, 2.2) acting on the ship (1), comprising the steps of: a) providing a data model, which comprises fixed data of the ship (1) and of the at least one tug (2, 2.1, 2.2) and variable environmental data; b) determining the current course, the thrust vector (10), and the inertial force of the ship (1) and specifying a desired travel direction (Fs) of the ship (1) with a subsequent calculation of the correction force vector (K) and a correction torque (M) required to achieve the desired travel direction (Fs); c) calculating the required positions, orientations, and drive settings of the at least one acting tug (2, 2.1, 2.2) using an algorithm that accesses the data model and generating control commands for the at least one tug (2, 2.1, 2.2) such that the sum of all the force vectors (FS1, FS2), and torques of the at least one acting tug (2, 2.1, 2.2) corresponds to the required correction force vector (K) and correction torque (M); d) transmitting the generated control commands to at least one acting tug (2, 2.1, 2.2) and monitoring the completion of the control commands; e) conducting an evaluation of the produced correction force vector and correction torque after completion of the control commands and generating and storing correction values in a data model when deviations are detected between the produced correction force vector (K′) and the required correction force vector (K) and/or between the produced correction torque (M′) and the required correction torque (M) and then repeating steps c) to e).

2. The method according to claim 1, wherein values are specified and in step e), the generating and storing of correction values in the data model are carried out upon detection of deviations of the produced correction force vector (K′) from the required correction force vector (K) and/or deviations of the produced correction torque (M′) from the required correction torque (M) that exceed the limit value and when the limit values are not exceeded, no correction values are generated and stored.

3. The method according to claim 2, wherein the fixed data in the data model include at least one of the following: a hull shape, main dimensions, a relative height of a tow line connection, characteristics of the skeg, a position of the propulsion systems, a type of propulsion systems, and a performance data of the propulsion systems of the ship (1) and/or at least one tug (2, 2.1, 2.2).

4. The method according to claim 3, wherein the variable data in the data model include at least one of the following: a length of the tow line (20) and a spatial position, a current travel speed and travel direction, a water depth, and a wind and/or wave load of the ship (1) and/or at least one tug (2, 2.1, 2.2).

5. The method according to claim 4, wherein the control commands comprise an angle (β) between the ship (1) and the at least one tug (2, 2.1, 2.2), an angle (σ) between the ship (1) and tow line (20), a heading of the at least one tug (2, 2.1, 2.2), and a rudder angle and/or thrust of the propulsion systems of the at least one tug (2, 2.1, 2.2).

6. The method according to claim 5, wherein the transmitted control commands are displayed in the at least one tug (2, 2.1, 2.2) and/or are read as default values into a dynamic positioning system of the at least one tug (2, 2.1, 2.2).

7. The method according claim 6, wherein the variable data also comprise limitations of a surrounding body of water from an electronic nautical chart as well as surrounding shipping traffic and are taken into account by the algorithm in a generation of the control commands.

8. The method according to claim 7, wherein the data model also comprises data about the permissible operating conditions of the at least one tug (2, 2.1, 2.2).

9. The method according to claim 1, wherein the fixed data in the data model include at least one of the following: a hull shape, main dimensions, a relative height of a tow line connection, characteristics of the skeg, a position of the propulsion systems, a type of propulsion systems, and a performance data of the propulsion systems of the ship (1) and/or at least one tug (2, 2.1, 2.2).

10. The method according to one of claim 1, wherein the variable data in the data model include at least one of the following: a length of the tow line (20) and a spatial position, a current travel speed and travel direction, a water depth, and a wind and/or wave load of the ship (1) and/or at least one tug (2, 2.1, 2.2).

11. The method according to claim 1, wherein the control commands comprise an angle (β) between the ship (1) and the at least one tug (2, 2.1 2.2), an angle (σ) between the ship (1) and tow line (20), a heading of the at least one tug (2, 2.1, 2.2), and a rudder angle and/or thrust of the propulsion systems of the at least one tug (2, 2.1, 2.2).

12. The method according to claim 1, wherein the transmitted control commands are displayed in the at least one tug (2, 2.1, 2.2) and/or are read as default values into a dynamic positioning system of the at least one tug (2, 2.1, 2.2).

13. The method according claim 1, wherein the variable data also comprise limitations of a surrounding body of water from an electronic nautical chart as well as surrounding shipping traffic and are taken into account by the algorithm in a generation of the control commands.

14. The method according to claim 1, wherein the data model also comprises data about the permissible operating conditions of the at least one tug (2, 2.1, 2.2).

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0035] The method according to this invention is explained in greater detail below in view of the drawings, wherein:

[0036] FIG. 1 schematically shows the acting forces and factors of a typical arrangement of a tug operating in an escort mode behind a ship to be assisted; and

[0037] FIG. 2 shows the forces and moments occurring in a towing train through the use of the method according to this invention.

DETAILED DESCRIPTION OF INVENTION

[0038] FIG. 1 shows the typical arrangement of a tug 2 operating in escort mode for a towing train, positioned behind a ship 1 to be assisted, which generates a propulsion vector 10 by its own propulsion or by another tug traveling ahead of it, not shown here. At the stern of the ship 1, the tug 2 is connected to the ship 1 by a tow line 20 and has the task of generating braking forces FB and steering forces FS. The force V in the tow line 20 is the result of all of the forces acting on the tug 2 as a result of the propulsion, the flow forces on the hull of the ship 1 and the hull of the tug 2, and any wind and wave loads. The angle between the ship 1 and the tow line 20 is referred to as θ and the angle between the longitudinal axis f of the tug 2 and the ship 1 is referred to as β.

[0039] FIG. 2 shows a schematic top view of a towing train comprising the ship 1 and a first tug 2.1 traveling ahead of it, which is connected to the bow of the ship 1 by a tow line 20, as well as a second tug 2.2, which is connected to the stern of the ship 1 by another tow line 20. Furthermore, possible positions of the tugs or of additional tugs relative to the ship 1 are also shown.

[0040] In a data processing system installed, for example, in a control room on board one of the tugs 2.1, 2.2 or in a remotely positioned control room, for example, on land, a data model that includes fixed data of the ship 1 and the tugs 2.1, 2.2 is stored in a corresponding memory. In this case, these data can involve the hull shape, the main dimensions such as the length, width, draft, and trim, as well as hydrostatic data about the ship 1 and the tugs 2.1, 2.2, which data are respectively present on board and are correspondingly stored manually or automatically or can be interpreted with regard to the respective current draft. The fixed data also include the relative height of the tow line connection of the individual tow line 20, the characteristics of the skeg, the position and type of propulsion systems and their performance data for both the ship and of the involved tugs 2.1, 2.2.

[0041] The data model also includes variable environmental data such as the length and spatial position of the tow line 20, which are either entered manually or are automatically detected by corresponding sensors, the speed and direction of the ship 1 and tugs 2.1, 2.2, which are read from the respective electronic chart display and information system (ECDIS), the water depth, which is likewise determined from the ECDIS or detected by onboard sensors, and environmental conditions such as wind and wave loads, which are detected by onboard sensors.

[0042] For a desired maneuvering task, the ship 1 can be moved in a desired travel direction Fs by the tugs 2.1, 2.2, which makes it necessary, depending on the circumstances explained based on FIG. 1, to pilot the tugs 2.1, 2.2 with the associated tow lines 20 to a particular optimal position and to operate with an optimal adjustment of the propulsion systems with regard to the produced thrust and direction. In this case, the tug 2.1 generates the force vector FS1 and the tug 2.2 generates the force vector FS2, which in the ideal case, add up to a resulting correction force vector K and a corresponding correction torque, which exactly produce the desired travel direction Fs of the ship. The difficulty lies in positioning the tugs 2.1, 2.2 so that the exactly required force vectors FS1, FS2 are produced, which requires precise knowledge of the conditions and a large amount of experience on the part of the involved skippers.

[0043] In an automated assistance system according to this invention, with a feedback of the thrust vector and/or the inertial force in the direction of the ship and the course of the latter, the data processing system determines the resulting correction force vector K and the correction torque required to achieve the specified desired travel direction FS of the ship.

[0044] An algorithm running on the data processing system balances the determined correction force vector K and the correction torque with the possible positions and orientations of the involved tugs 2.1, 2.2 shown in FIG. 2 and calculates the required positions, orientations, and drive settings of the acting tugs 2.1, 2.2 drawing on the data stored in the data model and generates corresponding control commands for the tugs 2.1, 2.2, which comprise the angle θ between the ship 1 and tow line 20, the angle β between the ship 1 and the tug 2.1 and 2.2, respectively, the heading of the tug 2.1, 2.2, the propulsion system/rudder angle, and the performance or speed and thrust of the individual tug 2.1, 2.2.

[0045] These generated control commands are transmitted to the acting tugs 2.1, 2.2 and are either merely displayed in the respective bridge in order to assist the captain in executing the required maneuver or are immediately converted into commands for a dynamic positioning system of the tugs 2.1, 2.2 so that the tugs 2.1, 2.2 automatically start the control commands. The accomplishment of the calculated control commands is monitored and is likewise fed back to the data processing system.

[0046] As soon as the calculated control commands of the tugs 2.1, 2.2 have been accomplished or executed, an evaluation of the actually produced correction force vector and correction torque is carried out and when deviations from the required correction force vector K and/or required correction torque are detected, corresponding correction values are stored in the data model so that the control commands can then be recalculated and transmitted to the tugs 2.1, 2.2 with the next evaluation so that the data model is continuously optimized.

[0047] As a result, according to the “machine learning” principle, a continuously optimizing data model of the towing train is obtained, which in a short time, as a default assistance value, determines or automatically sets the best position, orientation, and power output of the tugs 2.1, 2.2 in order to achieve the greatest possible effect with optimal efficiency.

[0048] In this connection, local circumstances of the channel, the prevailing traffic conditions, and dangerous operating conditions can be taken into account and failures can be automatically corrected.

[0049] The cable force specified by the system can be maintained statically or can also be intermittently increased through dynamic navigation.

[0050] Naturally, instead of the above-explained exemplary embodiment with two tugs 2.1, 2.2, it is also possible to calculate and control towing trains with only one tug or with more than two such tugs.

[0051] In any case, the involved tugs are utilized with optimal efficiency in the respective towing maneuver so that the duration of the towing maneuver and the fuel consumption required to execute it are minimized.

[0052] In summary, the method according to this invention forms the basis of an assistance system for the positioning and control of tugs in which the data basis for describing the individual capacity of the tug is generated by a continuous learning process and is continuously improved and the determination of the optimal position for assisting a ship can be carried out preferably operating in an escort mode, but also in other possible tug positions. An automatic starting of the position of the tugs and adjustment of the orientation of the ship are just as achievable as an automatic holding of the positions and automatic control of the generated pulling and pushing forces on the ship. Impermissible operating ranges, such as directions of the thrust jet for preventing harmful interactions between the thrust jet and the ship, as well as limitations within the channel and dangerous operating states, which can involve the danger of a tug capsizing, are reliably avoided. In addition to the use as a stand-alone system for an individual tug, it is also possible for a coordination of a plurality of tugs in the towing train to be carried out. Furthermore, in an enhanced upgrade level of the basic software, it is also possible to simulate corresponding assistance maneuvers.