KR102623953B1 - A ship having a plurality of propellers and a thrust allocation method therefor - Google Patents

Abstract

A plurality of thrusters installed at different locations to propel the ship; And a control unit formed by a controller that inputs the target position and calculates the final values of the required force and required moment by measuring the difference from the current position, and a thrust distributor that calculates the thrust and rudder angle of each of the plurality of propulsions. And, the thrust distributor selects a plurality of virtual values of the rudder angle and thrust of each of the thrusters, and selects the value with the minimum error from the final value among the combinations of each selected virtual value as the optimal value. Disclosed is a ship equipped with a plurality of thrusters that enables optimal thrust distribution without linearization or conversion to a convex function, and a thrust distribution method thereof.

Description

Ship equipped with multiple propellers and method of distributing its thrust {A SHIP HAVING A PLURALITY OF PROPELLERS AND A THRUST ALLOCATION METHOD THEREFOR}

The present invention relates to ships, and more specifically, to ships equipped with a plurality of propulsors and a method of distributing thrust thereof.

Ships use thrusters to reach the target location, and multiple thrusters are installed at different locations to reduce the detour distance and improve propulsion. At this time, the ship is moved by the sum of the thrust and moment generated from each thruster, so distributing the thrust to each thruster becomes an important factor.

Conventionally, when a plurality of thrusters are provided, the problem of thrust distribution was solved by linearizing it or dividing it into a convex function or transforming it. Specifically, the problem of thrust distribution is defined as an optimization problem such as linear programming or quadratic programming, and this is solved using numerical analysis techniques. In order to apply numerical analysis techniques, all constraints must be linear. It was defined as a linear matrix inequality in the form of a matrix equation or convex function.

However, in this case, there was a problem that it was difficult to use in cases where it was impossible to transform it into a linear or convex function, and there was a problem that it was essential to construct a linear or quadratic function to find the solution.
The conventional ship motion control method as described above is described in Japanese Patent Application Laid-Open No. 2018-176922 (Patent Document 1) and Japanese Patent Application Laid-Open No. 1996-119197 (Patent Document 2).

An embodiment of the present invention was devised to solve the above problems, and includes a ship equipped with a plurality of thrusters capable of optimal thrust distribution without the need for linearization or conversion to a convex function form when distributing thrust with a plurality of thrusters, and The purpose is to provide a method of distributing the thrust.

A ship equipped with a plurality of propulsors according to an embodiment of the present invention includes a plurality of propulsors installed at different positions to propel the ship; And a control unit formed by a controller that inputs the target position and calculates the final values of the required force and required moment by measuring the difference from the current position, and a thrust distributor that calculates the thrust and rudder angle of each of the plurality of propulsions. And, the thrust distributor selects a plurality of virtual values of the rudder angle and thrust of each of the thrusters, and selects the value with the minimum error from the final value among the combinations of each selected virtual value as the optimal value. do.

At this time, the thrust distributor adopts at least one of the maximum thrust change per unit time, the maximum usable thrust, the minimum usable thrust, the maximum rudder angle change per unit time, and the usable rudder angle area of each of the thrusters as a limit value, and within the limit value Characterized in that the virtual values are randomly selected.

The optimal value is preferably selected through a price function whose variable is the square of the error between the calculation value calculated by combining the selected virtual values and the final value.

In one embodiment of the present invention, a method of distributing thrust for a ship driven by a plurality of propellers includes receiving a target position; calculating the final values of the required force and required moment by measuring the difference between the target position and the current position; selecting a plurality of virtual values of the rudder angle and thrust of each of the thrusters and then selecting an optimal value among them; and transmitting the selected optimal value to an actuator that drives each thruster, wherein the step of selecting the optimal value is such that the error between the final value and the minimum among the combinations of the plurality of virtual values of each selected propeller is minimal. It is characterized in that the value of is selected as the optimal value.

Selecting the optimal value may include a first step of adopting a limiting value for each of the thrusters; a second step of randomly selecting the virtual values within the range of the limit values; A third step of calculating a plurality of calculated forces and calculated moments by combining a plurality of virtual values of each selected propeller; and a fourth step of substituting the calculated force, the calculated moment, the necessary force, and the necessary moment into a price function, and selecting the virtual value whose resulting value is the minimum as the optimal value.

The second step may adopt at least one of the maximum thrust change per unit time, the maximum usable thrust, the minimum usable thrust, the maximum rudder angle change per unit time, and the usable rudder angle area of each of the thrusters as the limit value.

The price function preferably includes as variables the square value of the error between the calculated force and the required force and the squared value of the error between the calculated moment and the required moment.

As discussed above, various effects including the following can be expected according to the problem-solving means of the present invention. However, the present invention does not need to have the following effects to be established.

The ship equipped with multiple propulsors and its thrust distribution method according to the present invention linearizes the thrust distribution problem by selecting a plurality of virtual values for the rudder angle and thrust of each propulsion and substituting them into a price function to select the optimal value. Alternatively, there is no need to transform it into a convex function, so a more specific and practical price function can be established. Therefore, it has the effect of improving utilization by enabling various thrust distributions.

In addition, more precise thrust distribution is possible by adopting limit values such as the maximum thrust change per unit time, maximum usable thrust, minimum usable thrust, maximum rudder angle change per unit time, and usable rudder angle area of each thruster.

In addition, the limit value can be more freely selected, enabling optimal thrust distribution to suit the user's various needs, providing improved convenience to the user.

1 is a diagram showing linearization of the prior art.
Figure 2 is a diagram showing a ship according to one embodiment of the present invention.
Figure 3 is a schematic diagram showing the control unit of the ship of Figure 2.
Figure 4 is a flow chart of a thrust distribution method for a ship according to an embodiment of the present invention.
Figure 5 is a flowchart of the steps for selecting the optimal value of Figure 4.

Hereinafter, specific embodiments of the present invention will be described in detail with reference to the drawings. At this time, when describing the present invention, detailed descriptions of well-known functions or configurations will be omitted so as not to confuse the gist of the present invention.

In addition, the ship propulsion method of one embodiment of the present invention relates to a ship equipped with a plurality of propulsors, and is applicable to a ship equipped with a plurality of propulsors of one embodiment of the present invention, and its purpose is the same. Therefore, in the detailed description of the ship, the control method will be omitted and explained together with the control method.

Figure 2 is a diagram showing a ship according to an embodiment of the present invention, and Figure 3 is a schematic diagram showing a control unit of the ship of Figure 2. Figure 4 is a flowchart of a thrust distribution method for a ship according to an embodiment of the present invention, and Figure 5 is a flowchart of the step of selecting the optimal value of Figure 4.

Referring to Figures 2 and 3, a ship 10 equipped with a plurality of propellers 20 in an embodiment of the present invention is installed in different positions and has a plurality of thrusters 20 to propel the ship 10 and a target. It includes a control unit 30 formed of a controller 31 through which a position is input, and a thrust distributor 32 that calculates the thrust and rudder angle of each of the plurality of propulsions, and the thrust distributor 32 determines the target position and the current Measure the difference in position to calculate the final values of the required force and required moment, select a plurality of virtual values of the rudder angle and thrust of each of the thrusters 20, and select the final value and the final value among the combinations of the selected virtual values. It is characterized by selecting the value with the minimum error as the optimal value.

The ship 10 is equipped with a propeller 20 and moves, and a plurality of thrusters 20 are used to improve propulsion and freedom. At this time, in order to move the ship 10 to a specific position, each of the plurality of thrusters 20 must have different thrust and rudder angles, and the ship 10 is propelled and driven according to the sum of the force and moment of each thruster 20. move

Therefore, in order to control the position of the ship 10, distribution of the thrust of each thruster 20 to have a specific force and moment becomes an important issue.

The propulsion machines 20 are installed in different positions of the ship 10 and are formed in plural pieces to propel the ship 10. At this time, the types of propellers 20 include various propellers such as fixed pitch propeller (FPP), variable pitch propeller (CPP), thruster, Voith-Schneider propeller, and water-jet. 20).

In addition, the thruster 20 has different values for the maximum thrust change per unit time, maximum usable thrust, minimum usable thrust, maximum rudder angle change per unit time, and usable rudder angle area depending on each type and location. As the number increases, the driving force and degree of freedom improve, but distribution of driving force is difficult.

The control unit 30 is formed of a controller 31 that inputs the target position of the ship 10 and a thrust distributor 32 that calculates the thrust and rudder angle of each of the plurality of thrusters 20. At this time, the target position is input directly by the user or automatically through the autonomous driving system. When the target position is directly input by the user, the controller 31 is connected to the steering device. Additionally, the controller 31 measures the difference between the target position and the current position, calculates the final values of the required force and required moment of the ship 10, and transmits them to the thrust distributor 32.

The thrust distributor 32 selects the optimal rudder angle and thrust of each of the plurality of thrusters 20 and transmits them to the driver 33 that drives each thruster 20. At this time, the thrust distributor 32 selects a plurality of virtual values of the rudder angle and thrust of each thruster 20, and selects the value with the minimum error from the final value among the combinations of each selected virtual value as the optimal value.

At this time, depending on the type and location of the thruster 20, there are different maximum thrust changes per unit time, maximum usable thrust, minimum usable thrust, maximum rudder angle change per unit time, and usable rudder angle area, so at least one of these is limited. It is desirable to select the value.

In other words, the thrust distributor 32 randomly selects a plurality of virtual values of the rudder angle and thrust of each thruster 20 within the selected limit value, and the operation value calculated by the combination of the selected virtual values and the controller 31 ) Compare the optimal values delivered in ) and select the combination that minimizes the error as the optimal value.

Specifically, the calculated value is formed by the calculated force and the calculated moment, and the optimal value is the value at which the sum of the square of the error between the calculated force and the required force and the square of the error between the calculated moment and the required moment is minimum. The virtual values of thrust thrust and rudder angle are selected as the optimal values.

In other words, the price function used to select the optimal value from the selected virtual values includes as variables the square of the error between the calculated force and the required force and the square of the error between the calculated moment and the required moment. Variables in the price function can include various variables depending on the user's needs, such as energy efficiency.

Therefore, the control unit 30 of the present invention does not define the thrust distribution of the plurality of thrusters 20, but uses the Monte Carlos method to find the optimal value through virtual values randomly selected within the limit value to find the optimal value. There is no need to linearize the problem or transform it into a convex function form, enabling optimized thrust distribution that takes into account a wider range of limiting values.

However, since virtual values must be randomly selected and calculation values must be calculated through each randomly selected virtual value, there is a limit to the calculation time when the number of thrusters 20 is formed above a certain level. Therefore, it is preferable that the ship 10 equipped with a plurality of thrusters 20 of the present invention is equipped with two or more thrusters 20 and five or less thrusters 20.

However, the scope of the present invention is not limited to this, and in the case of having a control unit 30 capable of performing multiple calculations at the same time, it can be applied even when more than five thrusters 20 are installed.

Therefore, the ship 10 equipped with a plurality of thrusters 20 according to an embodiment of the present invention is equipped with a control unit 30 that follows the Monte Carlos method to determine the rudder angle and rudder angle of each of the plurality of thrusters 20 to consider more various limit values. The thrust can be selected, allowing for greater usability and at the same time providing improved convenience to the user.

Hereinafter, the thrust distribution method of the controller 31 will be described in detail. However, the thrust distribution method of the ship in one embodiment of the present invention is a thrust distribution method that can be applied to the ship 10 equipped with a plurality of propulsors 20 in the above-described embodiment of the present invention, and the purpose and effect are the same, so The explained content will be omitted.

Referring to Figures 4 and 5, the control method of a ship 10 driven by a plurality of propulsors 20 in an embodiment of the present invention includes receiving a target position, measuring the difference between the target position and the current position, and Obtaining the final values of the required force and required moment, selecting a plurality of virtual values of the rudder angle and thrust of each of the propellers (20) and then selecting an optimal value among them, and applying the selected optimal value to each of the propellers (20) It includes the step of transmitting to the actuator 33 that drives, and the step of selecting the optimal value is the value at which the error from the final value is minimum among the combination of a plurality of virtual values of each selected propeller 20. It is characterized by selecting the optimal value.

Thrust distribution is to obtain the rudder angle and thrust that each of the plurality of thrusters 20 installed on the ship 10 at the current position should have in order to move the ship 10 to the desired target position, and is preceded by a step of receiving the target position. do. At this time, the target location may be entered directly by the user or automatically entered by a navigation system such as an autonomous navigation system.

When the target position is input, the relative position difference between the target position and the current position is measured to obtain the final values of the required force and required moment. At this time, the final value is formed by the force and moment required by the ship 10, and means the final target value through the thrust and rudder angle of each thruster 20.

Once the final value is obtained, the thrust distributor 32 selects a plurality of virtual values of the rudder angle and thrust of each thruster 20 and then performs a step of selecting the optimal value from the selected values. Specifically, the step of selecting the optimal value includes a first step of adopting the limit value of each thruster 20, a second step of randomly selecting virtual values within the limit value range, and A third step is to calculate multiple operation values by combining multiple virtual values, and a fourth step is to substitute the operation value and the final value into the price function and select the virtual value with the minimum result as the optimal value. is formed

In other words, the ship's thrust distribution method of the present invention provides a more practical thrust distribution method by applying the Monte Carlos method when selecting the rudder angle and thrust for each thruster (20).

The first step is to select the limiting value of each propeller 20, and the limiting conditions are selected according to the type and location of each installed propeller 20 to make the second step of selecting a virtual value more easily. do.

It is preferable that at least one of the maximum thrust change per unit time, the maximum usable thrust, the minimum usable thrust, the maximum rudder angle change per unit time, and the usable rudder angle area of each thruster 20 be adopted as the limit value.

However, the first step can be performed after the second step so that a virtual value is selected and a limit value is applied to calculate the calculation value only for the corresponding virtual value. However, as the number of thrusters 20 increases, the virtual value selection and calculation value are performed. Considering that the time required for calculation increases, it is preferable to perform it before virtual value selection.

The second step is a step of randomly selecting a plurality of values for the rudder angle and thrust of each propeller 20. When moving the ship 10 to the target position, conversion to a linear or convex function can be excluded, resulting in a more practical price. Allows you to specify a function.

The third step is a step of calculating a plurality of calculation values by combining the plurality of selected virtual values, and calculating the force and moment of the ship 10 that can be generated by the combination of the virtual values. Here, the calculated value means the calculated force and calculated moment of the ship 10 calculated through one virtual value of each propeller 20.

The fourth step is to select the optimal value by substituting the calculated value and the final value into the price function. Specifically, the price function is the square value of the error between the calculated force and the required force and the squared value of the error between the calculated moment and the required moment. The virtual value that is included as a variable and has the minimum result value is selected as the optimal value.

In other words, the thrust distribution method of the ship of the present invention is the final value actually required for the ship 10 to move from the current position to the target position and the optimal value that can be generated by each thruster 20 under the limiting conditions adopted by the user. Distribute thrust so that errors are minimized.

At this time, the optimal value is selected by a combination of virtual values randomly selected within the limit values, thus improving usability by excluding the process of linearizing or converting the problem into a convex function under certain limiting conditions and considering various limiting conditions.

In addition, there is no need to use the first or second order terms when determining the price function, providing a more practical thrust distribution method. For example, if you want to consider the RPM of the propeller 20 in the price function, a 3/2 squared variable must be included, which has the limitation that it is difficult to apply with the conventional thrust distribution method. However, in the thrust distribution method for a ship of the present invention, the Applicable.

When the optimal value is selected, the thrust distributor 32 transfers the optimal values to the driver 33 that drives each thruster, and the driver 33 controls the thruster 20 to have the rudder angle and thrust of each thruster 20. Drive to move the ship to the target location.

Although preferred embodiments of the present invention have been described above by way of example, the scope of the present invention is not limited to these specific embodiments, and any appropriate changes that can be made within the scope of the patent claims are within the scope of protection of the present invention. It applies.

10 ships
20 propeller 30 control unit
31 Controller 32 Thrust distributor
40 actuator

Claims (7)

Multiple thrusters installed at different locations to propel the ship, but with rudder angle limitations; and
A control unit formed by a controller in which the target position is input and the difference from the current position is calculated to calculate the final values of the required force and required moment, and a thrust distributor that calculates the thrust and rudder angle of each of the plurality of propulsions; ,
The thrust distributor is
At least one of the maximum thrust change per unit time, the maximum usable thrust, the minimum usable thrust, the maximum rudder angle change per unit time, and the usable rudder angle area of each of the thrusters is adopted as a limit value, and each of the thrusters within the limit value is selected. A plurality of virtual values of rudder angle and thrust are randomly selected, and the calculated value calculated by the combination of the selected virtual values is compared with the final value transmitted from the controller to select the value with the minimum error as the optimal value. A ship equipped with a plurality of propellers, characterized in that:
delete According to paragraph 1,
The optimal value is
A ship equipped with a plurality of propulsors, characterized in that the square of the error between the calculated value and the final value is selected through a price function with the value as a variable.
In a method of distributing thrust for a ship driven by a plurality of thrusters,
Receiving a target location as input;
calculating the final values of the required force and required moment by measuring the difference between the target position and the current position;
selecting a plurality of virtual values of the rudder angle and thrust of each of the thrusters and then selecting an optimal value among them; and
A step of transmitting the selected optimal value to an actuator that drives each of the propellers,
The step of selecting the optimal value is
A first step of adopting at least one of the maximum thrust change per unit time, the maximum usable thrust, the minimum usable thrust, the maximum rudder angle change per unit time, and the usable rudder angle area of each of the thrusters as a limit value;
a second step of randomly selecting the virtual values within the range of the limit values;
A third step of calculating a plurality of calculated forces and calculated moments by combining a plurality of virtual values of each selected propeller.
A fourth step of substituting the calculated force, the calculated moment, the necessary force, and the necessary moment into a price function and selecting the virtual value with the minimum result as the optimal value. Thrust distribution method.
delete delete According to clause 4,
The price function is
A thrust distribution method for a ship, characterized in that it includes the square value of the error between the calculated force and the required force and the squared value of the error between the calculated moment and the required moment as variables.

Images