Ship route planning based on wind and ocean current information

Abstract

This invention provides a method for route planning for marine vessels that partially mitigates the effects of environmental disturbances such as wind and ocean currents on the movement of vessels. [Solution] A computer implementation method is provided that acquires wind data indicating the strength and direction of the wind for an ocean vessel (S102), acquires ocean current data indicating the strength and direction of the ocean current for an ocean vessel (S104), detects the position of an obstacle in front of the ocean vessel (S106), determines constraints that are adjusted based on the wind data and ocean current data in relation to the distance the ocean vessel has traveled from the obstacle to the obstacle (S108), generates a route for the ocean vessel to counter the wind and ocean current calculated based on the wind data and ocean current data while complying with the constraints (S110), and provides output data of the generated route (S112).

Description

[Technical Field]

[0001] The present invention generally relates to a computer implementation method for generating routes for marine vessels, a control unit for performing the method, a marine vessel equipped with the control unit, and a corresponding computer program product. [Background technology]

[0002] Route planning algorithms play a crucial role in optimizing performance and ensuring the successful execution of missions for offshore vessels. These algorithms are responsible for generating positional trajectories and speed profiles while considering various constraints, such as propulsion capabilities and obstacles in the ocean. To plan the optimal and safe route for a ship, environmental disturbances such as wind and ocean currents, which often affect the ship's motion, must be taken into account. [Overview of the project]

[0003] In consideration of the aforementioned and other drawbacks of the prior art, the object of the present invention is to provide a method for route planning for marine vessels that at least partially mitigates the drawbacks of the prior art.

[0004] According to a first aspect of the present invention, a computer implementation method for generating a route for an ocean vessel is provided, the method comprising: acquiring wind data indicating the strength and direction of wind to the ocean vessel; acquiring ocean current data indicating the strength and direction of ocean currents to the ocean vessel; detecting the position of at least one obstacle in front of the ocean vessel; determining constraints relating to the distance the ocean vessel has traveled from the obstacle; generating a route for the ocean vessel to face the wind and ocean currents calculated based on the wind data and ocean current data, while adhering to the constraints, wherein the constraints are adjusted based on the wind data and ocean current data to ensure a buffer distance to at least one obstacle, and output data of the generated route is provided.

[0005] The present invention is at least in part based on realizing the adaptive adjustment of constraints to account for wind and ocean currents so that a safe buffer distance to obstacles can be ensured despite changing wind and ocean current conditions. Constraints that may be associated with stationary and / or moving obstacles are thus fine-tuned based on the direction and strength of the wind and ocean currents. The amount of constraint adjustment depends on the magnitude of the wind and ocean currents.

[0006] The safety of marine vessel navigation is improved by dynamically adjusting path constraints based on real-time wind and ocean current data and ensuring sufficient buffer distance from obstacles. Additionally, embodiments of the present disclosure provide improved maneuverability in changing conditions and minimize collision risk, and can be implemented continuously and autonomously.

[0007] Wind and ocean current data can be obtained by onboard sensors or by land-based or offshore weather stations that transmit data to ocean-going vessels.

[0008] The location of an obstacle can be determined by onboard sensors such as radar and lidar, and / or by receiving navigation data such as GPS signals, or position data received from a secondary offshore vessel.

[0009] In embodiments, the generated path may be determined to minimize the energy required to counteract wind and ocean currents. Advantageously, the energy consumption of offshore vessels can be reduced by incorporating the energy required to counteract environmental forces into the path planning generation, thereby reducing fuel use and operating costs. For example, generating a path may involve using an objective function that includes minimizing the energy required to counteract wind and ocean currents.

[0010] In embodiments, the objective function may further include minimizing the propulsion energy required for the ocean vessel while traveling along a route. By including propulsion energy minimization in the objective function, the system not only takes into account environmental forces caused by wind and ocean currents, but also ensures that the vessel is operated efficiently. Advantageously, this can reduce fuel consumption and lower operating costs while maintaining optimal route planning performance for the ocean vessel.

[0011] In embodiments, mathematical models of environmental forces caused by wind and ocean currents on ocean vessels may be included in the objective function. Using mathematical functions of environmental forces can increase the accuracy of the generated path because the effects of wind and ocean currents can be quantified more precisely. This provides a safer and more energy-efficient generated path.

[0012] Using mathematical models for wind and ocean currents, the energy required to offset the effects of wind and ocean currents can be incorporated as a term in the objective function.

[0013] In embodiments, buffer distances may be selected to allow the operator to manually avoid obstacles in the event of unexpected events affecting the current path compared to the generated path. In other words, buffer distances are selected to allow the operator to control the offshore vessel and still be able to navigate the vessel safely despite obstacles. For example, this provides a fail-safe mechanism and allows human intervention in situations where the current path may need to be quickly altered, such as when unexpected obstacles or changing environmental conditions occur. Buffer distances are selected based on operator maneuvering criteria or a database of maneuverability data that can be manually adjusted.

[0014] In the embodiment, the adjustment of constraints may depend on the strength and direction of wind and ocean currents. The constraints can be dynamically adjusted as wind and ocean currents change. That is, as wind and ocean currents change, the path constraints are adjusted accordingly to maintain optimal buffer distance and energy efficiency.

[0015] In some embodiments, the obstacles can include moving obstacles and stationary obstacles. This reduces the risk of collisions in unpredictable situations, especially those affected by wind and ocean currents.

[0016] Preferably, the method can be continuously executed when the marine vessel is in operation.

[0017] In an embodiment, the adjustment can include virtually moving the obstacle in a direction opposite to the environmental forces calculated based on wind data and ocean current data. Virtually moving here means adjusting the location of the obstacle in the calculation to include the changes in their positions caused by wind and ocean currents. This provides an easy way to include the influence of wind and ocean currents on moving obstacles. The degree of this adjustment depends on the magnitude of the wind and ocean currents.

[0018] The method can be executed autonomously for at least a partially autonomous marine vessel.

[0019] According to a second aspect of the invention, a control unit is provided that is configured to perform the steps according to any one of the embodiments of the first aspect.

[0020] Further effects and features of the second aspect of the invention are mostly similar to those described above in relation to the first aspect of the invention.

[0021] A marine vessel comprising a control unit is further provided.

[0022] According to a third aspect of the invention, a computer program product is provided for performing the method described herein when executed by a control unit.

[0023] The computer program product includes program code for acquiring wind data indicating the strength and direction of wind for an ocean vessel, acquiring ocean current data indicating the strength and direction of ocean currents for an ocean vessel, detecting the position of obstacles ahead of the ocean vessel, determining constraints related to the distance the ocean vessel has to travel from obstacles, and generating a route for the ocean vessel to counter the wind and ocean currents calculated based on the wind and ocean current data while adhering to the constraints, wherein the constraints are adjusted based on the wind and ocean current data to ensure a buffer distance to obstacles, and output data of the generated route is provided.

[0024] Further effects and features of the third aspect of the present invention are largely similar to those described above in relation to the first and second aspects of the present invention.

[0025] Further features and advantages of the present invention will become apparent upon consideration of the appended claims and the following description. Those skilled in the art will recognize that different features of the present invention can be combined to create embodiments other than those described below, without departing from the scope of the invention.

[0026] These and other aspects of the present invention will now be described in more detail with reference to the accompanying drawings illustrating exemplary embodiments of the present invention. [Brief explanation of the drawing]

[0027] [Figure 1] A schematic example of an offshore vessel according to an embodiment of the present invention is provided below. [Figure 2] This is a flowchart of the method steps according to an embodiment of the present invention. [Figure 3] The following schematic examples illustrate marine vessels, obstacles, and generated paths according to embodiments of the present invention. [Modes for carrying out the invention]

[0028] In embodiments for carrying out the present invention, various embodiments of the invention are described herein with reference to specific implementations. Certain technical terms are used for clarity when describing embodiments. However, the present invention is not intended to be limited to such selected technical terms. Certain illustrative embodiments are discussed, but it should be understood that these are for illustrative purposes only. Those skilled in the art will recognize that other components and configurations may be used without departing from the scope of the present invention.

[0029] Figure 1 schematically shows a top view of an offshore vessel 10. The offshore vessel 10 may be, for example, a ship or a floating production, storage, and offloading (FPSO) unit. The vessel 10 comprises a number of thrusters, in this case a first thruster 12a, a second thruster 12b, a third thruster 12c, and a fourth thruster 12d. One, some, or all of the thrusters 12a-12d may also be referred to by reference number "12".

[0030] Each thruster 12 is rotatable in different thrust directions within a horizontal plane (parallel to the drawing plane in Figure 1). Each thruster 12 may comprise a propeller and an engine that drives the propeller. The thrust of the thruster 12 can be increased by increasing the engine speed of the engine, and vice versa. Although the thruster 12 is exemplified here as an azimuth thruster, other types of thrusters are also conceivable.

[0031] The vessel 10 further comprises a control system 14. In this example, the control system 14 comprises a control unit 16 and a memory 18. The memory 18 stores a computer program 20. The computer program 20 comprises program code that, when executed by the control unit 16, causes a data processing device or the control unit 16 to perform or instruct it to perform various steps described herein.

[0032] As shown in Figure 1, a model 21 of the vessel 10 can be stored in memory 18. The model 21 may be, for example, a nonlinear model of the vessel 10 that describes the motion of the vessel 10 in a horizontal plane.

[0033] The vessel 10 in this example further comprises one or more sensors, exemplified here as a position sensor 22. The position sensor 22 is configured to provide position data 24 to a control system 14. The position data 24 indicates the position of the vessel 10 in a horizontal plane. The position sensor 22 may be, for example, a GPS device that further provides map data to the control system 14. The marine vessel 10 may further have access to the charts 23 and map data 23 from memory 18 or from a server 36.

[0034] The vessel 10 further comprises sensors 26, 30 for detecting wind strength and direction and ocean current strength and direction. Wind data 28 may be provided to the control system 14 from the wind sensor 26, and ocean current data 32 may be provided to the control system 14 from the ocean current sensor 30. Alternatively or additionally, the control system 14 may remotely receive wind data and / or ocean current data from a land-based or offshore weather station 36 or server 36 using wireless communication technology 34.

[0035] When operating the ocean vessel 10 along a route, the control system 14 controls the thrusters 12 to propel the ocean vessel from a first position to a second position. When moving along a route, it is desirable to find a safe route that can avoid collisions with obstacles and also provide optimized energy consumption. However, wind and ocean currents complicate not only the operation of the ocean vessel but also the estimation of how obstacles such as secondary ocean vessels are affected by wind and ocean currents. To improve safety for ocean vessels, embodiments of this specification propose generating a route for ocean vessels in which wind and ocean currents are taken into account by introducing constraints related to the pass-through distance from obstacles for the ocean vessel, and the constraints are adjusted based on wind and ocean current data to ensure a buffer distance to each of the obstacles. Preferably, the generated route balances safety and energy consumption. In other words, when generating a route, safety takes precedence while minimizing energy consumption.

[0036] Figure 2 is a flowchart of the method steps according to an embodiment of the present invention. Figure 3 schematically illustrates an ocean vessel 10 moving along a path under the influence of wind and ocean currents. Figures 2 and 3 are described together.

[0037] An ocean vessel 10 is moving across the sea and is attempting to turn around a stationary obstacle 50. Ahead of vessel 10 is another moving obstacle 40 in the form of a secondary vessel 40. Both the host ocean vessel 10 and the secondary ocean vessel 40 are under the influence of wind 54 and ocean current 56. In this example, wind 54 is coming from the starboard side of the host ocean vessel 10, and ocean current 56 is coming from the stern side of the host vessel 10. The turn around the stationary obstacle 50 will move the host ocean vessel 10 from its current position towards port.

[0038] In step S102, the control unit 16 acquires wind data 28 indicating the strength and direction of the wind 54 for the ocean vessel 10. Here, the wind is the wind at the location of the ocean vessel 10 and in its vicinity.

[0039] In step S104, the control unit 16 acquires ocean current data indicating the strength and direction of the ocean current 56 relative to the ocean vessel. Note that the ocean current 56 is in the vicinity of the ocean vessel 10.

[0040] In step S106, the control unit 16 detects the positions of obstacles 40, 50 in front of the ocean vessel 10. The positions may be detected from map data, particularly for stationary obstacles 50 such as land and islands. The position of the ocean vessel 40 may be obtained from services such as GPS data transmitted from a secondary vessel to the host ocean vessel, but position data may also be obtained by detection using radar and lidar or similar.

[0041] In step S108, the control unit 16 determines constraints related to the cruising distances D1 and D2 from each of the obstacles 40 and 50 for the ocean vessel 10. The constraints may differ depending on the type of obstacle. Moving obstacles such as ocean vessels 40 may require a longer cruising distance D2 than stationary obstacles 50 because the uncertainty of the position of the moving obstacle is greater than the uncertainty of the position of stationary obstacles 50. Furthermore, the type of moving object 40 may also affect the constraints on the cruising distance D2. For example, a large ship may require a different cruising distance than a small ship.

[0042] In step S110, the control unit 16 generates a route P for the ocean vessel 10 to face the wind 54 and ocean current 56 calculated based on the wind data 28 and ocean current data 32, while adhering to constraints. The constraints are adjusted based on the wind data and ocean current data to ensure buffer distances B1 and B2 to obstacles 40 and 50. More precisely, the adjustment of the constraints depends on the strength and direction of the wind 54 and ocean current 56, where the constraints are dynamically adjusted as the wind and ocean current change. This is particularly advantageous when the method described herein is continuously performed as the ocean vessel is in operation. In other words, the generated route P is updated at a certain frequency to capture changing circumstances or conditions, such as the presence of obstacles and changing wind and ocean current.

[0043] In step S112, the control unit 16 provides output data 60 of the generated path. The output data 60 can be used by the control system 14 to control the propulsion of the ocean vessel 10 along the generated path. The output data 60 may include, for example, control signals for controlling the thrusters 12 of the propulsion system so that the generated path can be automatically followed.

[0044] The generated path is preferably determined to minimize the energy required to counteract wind and ocean currents. To this end, generating the path may preferably involve using an objective function 38 that includes minimizing the energy required to counteract wind and ocean currents. The objective function 38 may include minimizing the propulsion energy required for the ocean vessel 10 while traveling along the path.

[0045] Determining a path P can be achieved in various ways other than using an objective function. One possible methodology for generating path P is to utilize techniques such as rule-based methods. These rely on predefined rules and heuristics to derive a path plan without formal optimization. Another possibility is to use machine learning techniques such as reinforcement learning, where the system learns the optimal path through trial and error rather than explicitly optimizing a mathematical function. Additionally, multi-objective optimization can be used, allowing for a more flexible approach that balances multiple performance criteria simultaneously rather than optimizing a single objective function. Other exemplary algorithms include genetic algorithms, convolutional neural networks, or recurrent neural networks, to give a few further examples.

[0046] Here, as an example, an optimization problem for generating a path P that utilizes objective function 38 is described.

[0047] The optimization problem can be formulated as follows:

[0048]

number

[0049] Here, (OP1) represents the objective function, which includes several terms:

[0050] t f This is the duration of control.

[0051] s c , s w These are slack variables, respectively, corresponding to the safe distances B1 and B2 from the boundary of the obstacle with respect to the direction of ocean current and wind. For example, the desired safe distance or buffer distance B1 and B2 from the obstacle may be set to, for example, 50 meters. However, in narrow waterways, maintaining the desired buffer distance, for example, 50 meters, may not be feasible. In such cases, the slack variables allow the optimization algorithm to find a solution that is as close as possible to the target safe distance, in this example, 50 meters.

[0052] q c ,q w This is a weight in the objective function that penalizes the safe distance, and it controls the importance of the safe distance in optimization compared to other terms.

[0053] E is a term that represents the energy consumption required to mitigate the effects of ocean currents and winds.

[0054] q E This represents the weight of the penalty imposed on energy consumption.

[0055] Therefore, the objective function includes four terms to ensure time optimality, safe distance from ocean currents and winds, and energy optimality. The decision variables for the optimization problem include the position and velocity trajectories for maneuvering the vessel, the forces and torques required to follow these trajectories, and the duration of the maneuvering task.

[0056] In the optimization problem, (OP2) represents constraints corresponding to the kinematic and kinetic equations of the ocean vessel 10. These constraints ensure that the path generated by solving the optimization problem follows the equations of motion of the vessel 10, thereby guaranteeing dynamic feasibility. In equation (OP2),

[0057]

number

[0058] This represents the position and orientation of the ship as represented on a fixed Earth frame, where x and y are the north and east distances from the NED (North-East-Down Coordinate System) origin to the ship's center of gravity, respectively, and φ is the bow azimuth angle. The ship's velocity vector is,

[0059]

number

[0060] This is expressed as follows, where u is the fixed body velocity in the surge (forward / backward direction) (along the longitudinal axis of the ship), v is the fixed body velocity in the sway (left / right direction) (across that axis), and r is the fixed body yaw rate (angular velocity). The rotation matrix R(φ) is given by:

[0061]

number

[0062] In equation (OP2), M is the body inertia matrix, which is the sum of the rigid body mass and the hydrodynamically added mass. The C(ν) matrix includes nonlinear terms resulting from the Coriolis effect and centripetal effect. The matrix D(ν) includes the hydrodynamic damping force or drag force.

[0063]

number

[0064] captures the total forces and moments due to thrusters, where F x , F y , and M r are the forces and torques acting on surge, sway, and yaw dynamics, respectively. ω is the rate of change of the forces generated by the ship's thrusters.

[0065] The inequality constraints (OP3) and (OP4) correspond to the capabilities of the propulsion system of the marine vessel 10. These constraints impose limits on the forces and torques generated by the thrusters of the marine vessel, as well as on the rate at which the forces generated by each thruster can change. The matrix A τ , B, b τ in (OP3) are calculated based on the positions of the thrusters of the marine vessel and the thruster limitations regarding the magnitude and direction of the forces that the thrusters can generate.

[0066] The equality constraints (OP5) and (OP6) represent the current state of the marine vessel. These constraints ensure that the optimization problem is initialized with the current position and velocity of the marine vessel and enable the marine vessel 10 to smoothly follow the generated path without sudden maneuvers.

[0067] The inequality constraints (OP7) and (OP8) correspond to maintaining a safe distance with respect to the directions of the ocean current and wind. e wind and e current are unit vectors along the velocity vectors of the wind and ocean current, respectively. These vectors are calculated as follows.

[0068]

Equation

[0069] Here, V wind , V current are the velocities of the wind and ocean current in the north and east components (Earth frame coordinates). d windd is the desired distance from the boundary with respect to the wind direction, and it can be adjusted according to the wind strength, i.e., smaller for weaker winds. wind For strong winds, larger d wind The same principle applies to d current This also applies to matrix A. s , b s This is calculated based on the location of obstacles around the ocean vessel 10. These matrices define collision-free polygons, which can then be used by the algorithm to find a safe path. In these two inequalities, c rot (φ) is the rotation matrix from the object frame to the Earth frame, and is given by the following:

[0070]

number

[0071] Preferably, a mathematical model of the environmental forces caused by wind and ocean currents on an ocean vessel is included in the objective function 38. The mathematical model is used to calculate the energy consumption E, which is a function of the forces and torques exerted on the ocean vessel 10 by wind and ocean currents. These forces and torques are calculated using a mathematical model that takes the magnitude and direction of the wind and ocean currents as input, along with the position, speed, and dimensions of the vessel, and outputs the corresponding forces and torques.

[0072] buffer distance s c , s w This may be selected to allow the operator to manually avoid obstacles in the event of an unexpected event affecting the current route compared to the generated route. That is, a slightly larger slack s may be selected so that the operator can interrupt and take over the operation of the vessel 10. c , s w The following can be selected. As discussed above, the slack variable s c , s wThis can be initialized based on the operator's preferred safe distance during operation, for example, 50 meters. The optimization algorithm will endeavor to satisfy this preference, but this may not always be feasible in situations such as narrow waterways or congested spaces. In such cases, the optimization algorithm will find the closest possible value to the desired safe distance.

[0073] The constraint adjustment can be performed by virtually moving obstacles 40 and 50 in the opposite direction to the environmental forces calculated based on wind and ocean current data. That is, the control unit 16 can virtually move objects to simulate the effects of environmental forces for path calculation. In equations OP7 and OP8, this is represented by the vector e pointing in the opposite direction to the ocean currents and wind. wind and e current These are represented by the vectors. These vectors shift the position of the obstacle accordingly.

[0074] For example, virtually moving an object to adjust constraints is done by approximating the object with a polygon that encloses its location on the map, whether stationary or moving. The polygon preferably completely encloses the obstacle. For example, one technique is to calculate the convex hull of the obstacle's boundary points. The polygon is then shifted in the opposite direction using a linear transformation, based on the wind and ocean current directions. The magnitude of the wind and ocean currents determines the degree of this shift.

[0075] The method described herein can be performed autonomously by a control unit 16 for at least a partially autonomous offshore vessel 10.

[0076] The method described herein preferably generates a route for the automatic control of a vessel and, optionally, optimizes both travel time and energy efficiency. It not only mimics the actions of a skilled human operator but also improves performance criteria such as time and energy. However, unlike a human operator, the control unit can calculate the entire route P for the current maneuvering task from start to finish in one go.

[0077] The computer program product 20 includes program code for performing the method described herein, which includes at least code for acquiring wind data indicating the strength and direction of wind to an ocean vessel, acquiring ocean current data indicating the strength and direction of ocean currents to an ocean vessel, detecting the position of obstacles ahead of the ocean vessel, determining constraints related to the distance the ocean vessel has traveled from the obstacles, and generating a route for the ocean vessel to face the wind and ocean currents calculated based on the wind data and ocean current data while adhering to the constraints, wherein the constraints are adjusted based on the wind data and ocean current data to ensure a buffer distance to the obstacles, and output data of the generated route is provided.

[0078] The control unit may include a microprocessor, microcontroller, programmable digital signal processor, or other programmable device. The control unit may also, or instead, include an application-specific integrated circuit, a programmable gate array or programmable array logic, a programmable logic device, or a digital signal processor. If the control unit includes a programmable device such as the aforementioned microprocessor, microcontroller, or programmable digital signal processor, the processor may further include computer executable code that controls the operation of the programmable device.

[0079] In one or more examples, the described functions may be implemented in hardware, software, firmware, or any combination thereof. If implemented in software, these functions may be stored as one or more instructions or codes on a computer-readable medium, or transmitted through a computer-readable medium and executed by a hardware-based processing unit. The computer-readable medium may include computer-readable storage media corresponding to tangible media such as data storage media, or communication media including any medium that facilitates the transfer of computer programs from one location to another, for example, according to a communication protocol. Thus, the computer-readable medium may generally correspond to (1) non-transient tangible computer-readable storage media, or (2) communication media such as signals or carrier waves. The data storage medium may be any available medium that can be accessed by one or more computers or one or more processors to retrieve instructions, codes and / or data structures for implementing the techniques described herein. A computer program product may include computer-readable media.

[0080] Such computer-readable storage media may include, but are not limited to, RAM, ROM, EEPROM®, CD-ROM or other optical disk storage devices, magnetic disk storage devices or other magnetic storage devices, flash memory, or any other media that can be used to store desired program code in the form of instructions or data structures and that can be accessed by a computer.

[0081] While the present invention has been described with reference to its specific illustrative embodiments, many different variations, modifications, and similarities will become apparent to those skilled in the art.

[0082] In addition, variations of the disclosed embodiments can be understood and achieved by those skilled in the art when carrying out the claimed invention, based on a review of the drawings, disclosures, and appended claims. In the claims, the word “equips” does not exclude other elements or steps, and the indefinite article “a” or “an” does not exclude the plural. The mere fact that certain means are described in different dependent claims does not imply that combinations of these means cannot be used advantageously.

Claims

1. A computer implementation method for generating a route (P) for an ocean vessel (10), wherein the method is: To acquire wind data (28) indicating the strength and direction of the wind for the aforementioned offshore vessel (S102), Obtain ocean current data (32) indicating the strength and direction of the ocean current for the aforementioned ocean vessel (S104), The position of at least one obstacle (40, 50) in front of the ocean vessel (10) is detected (S106), Determining constraints related to the distance (D1, D2) the ocean vessel (10) has to travel from the obstacles (40, 50) (S108), While adhering to the aforementioned constraints, a route (P) for the offshore vessel (10) to face the wind and ocean currents calculated based on the wind data and ocean current data is generated (S110), where the constraints are adjusted based on the wind data and ocean current data to ensure buffer distances (B1, B2) to the obstacles (40, 50). To provide the output data (60) of the generated route (S112) A method that includes [a certain feature].

2. The method according to claim 1, wherein the generated path is determined to minimize the energy (E) required to counteract the wind and ocean currents.

3. The method according to claim 1 or 2, wherein generating the aforementioned path involves using an objective function (38) that includes minimizing the energy required to counteract the wind and ocean currents.

4. The method according to claim 3, wherein the objective function further comprises minimizing the propulsion energy required for the ocean vessel (10) while traveling along the path.

5. The method according to claim 3 or 4, wherein a mathematical model of the environmental forces caused by wind and ocean currents on the ocean vessel is included in the objective function.

6. The method according to any one of claims 1 to 5, wherein the buffer distances (B1, B2) are selected to allow the operator to manually avoid obstacles in the event of an unexpected event affecting the current path compared to the generated path.

7. The method according to any one of claims 1 to 6, wherein the adjustment of the constraints depends on the strength and direction of the wind and ocean currents.

8. The method according to any one of claims 1 to 7, wherein the constraints are dynamically adjusted as the wind and ocean currents change.

9. The method according to any one of claims 1 to 8, wherein the obstacles include moving obstacles and stationary obstacles.

10. The method according to any one of claims 1 to 9, which is performed continuously while the ocean vessel is in operation.

11. The method according to any one of claims 1 to 10, wherein the adjustment includes virtually moving the obstacle in a direction opposite to the environmental forces calculated based on the wind data and the ocean current data.

12. The method according to any one of claims 1 to 11, wherein the method is performed autonomously for at least a partially autonomous ocean vessel.

13. A control unit (16) configured to perform the method described in any one of claims 1 to 12.

14. An offshore vessel (10) comprising the control unit (16) according to claim 13.

15. A computer program product (20) comprising program code for performing the method according to any one of claims 1 to 12 when executed by a control unit.

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