Control method and propulsion system for a marine vessel

Abstract

A method of controlling a propulsion system (102) of a marine vehicle (100) by a controller (112), comprising forming data regarding a pitch angle (γ(θ)) of the at least one foil (108, 108') based on an angle variable wake field (W(θ)) affecting the at least one foil (108, 108') and an angle (θ) of rotation of a foil wheel (106, 106'), wherein an actuator device (110) receiving data from the controller (112) sets the at least one foil (108, 108') at a pitch angle (γ(θ)) based on the data.

Description

[Technical Field]

[0001] This invention relates to the sea ship This relates to a control method for a propulsion system and to a propulsion system. [Background technology]

[0002] sea ship The vessel is able to move relative to the surrounding water using thrust from a propulsion system, which includes one or more rotating foil wheels with individually controllable foils extending vertically downward. With individual foil pitch control, a typical propulsion system operates with relatively high efficiency. Efficiency is based on optimizing the foil pitch angle using either a trochoidal path that depends on a function with constant eccentricity and foil wheel rotation angle as arguments, or a path described by a trigonometric function with variable eccentricity and foil wheel rotation angle as arguments.

[0003] However, conventional techniques merely perform parametric optimization, failing to adequately consider real-world conditions, resulting in model coefficients optimized only for a single operating point, such as velocity or thrust. If another operating point is required, the model coefficients must be optimized again for best performance. This is a cumbersome process, ultimately requiring numerical maps of all model coefficients to cover the entire operating range. Overall, such a process is impractical or even impossible, which can ultimately lead to low efficiency, low thrust, propulsion system wear, and high fuel consumption, and consequently, increased pollution and health risks.

[0004] Therefore, improvement is desired. [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] U.S. Patent Application Publication No. 2015 / 0321740

Patent Document 2

Patent Document 3

Summary of the Invention

[0006] The present invention aims to provide improved control.

[0007] The present invention is defined by the independent claims. Embodiments are defined by the dependent claims.

[0008] Exemplary embodiments of the present invention will be described below by way of example only with reference to the accompanying drawings.

Brief Description of the Drawings

[0009] [Figure 1] A diagram showing an example of a marine vessel. [Figure 2] A diagram showing an example of a propulsion system. [Figure 3] A diagram showing examples of symmetric smooth square waves and asymmetric smooth square waves. [Figure 4] A diagram showing an example of a foil rotating at an angular velocity at any foil position. [Figure 5] A diagram showing an example of arranging a calculation probe or sensor adjacent to at least one foil. [Figure 6] A diagram showing an example of instantaneous foil efficiency, target angle of attack, and actual angle of attack. [Figure 7] A diagram showing an example of the pitch angle trajectory of a foil with respect to the rotation angle of a foil wheel. [Figure 8] A diagram showing an example of a flowchart of a control method. [[ID=5x]]

Modes for Carrying Out the Invention

[0010] The following embodiments are merely examples. Although this specification may refer to "one" embodiment in several places, this does not necessarily mean that each such reference is to the same embodiment, or that the feature applies only to a single embodiment. It is also possible to combine the single features of different embodiments to provide other embodiments. Furthermore, the terms "comprising" and "including" should be understood not to limit the described embodiments to consisting only of the recited features, and such embodiments may also include features / structures not specifically recited. All combinations of embodiments are considered possible if they do not result in a structural or logical contradiction.

[0011] The figures show various embodiments, but it should be noted that they are schematic diagrams showing only some structural and / or functional entities. The connections shown in the figures may refer to logical or physical connections. It will be apparent to those skilled in the art that the described apparatus and / or system may include other functions and structures in addition to those described in the figures and text. It should be understood that some of the details of the functions, structures, and signal transmissions used for measurement and / or control are irrelevant to the actual invention. Therefore, it is not necessary to explain them in more detail here.

[0012] FIG. 1 shows an example of a marine ship 100 (the marine ship is only partially shown in FIG. 1) having a propulsion system 102 comprising two propulsion subsystems 104, 104'. In general, the propulsion system 102 can comprise one or more propulsion subsystems 104, 104'. The marine ship can include transport ships and passenger ships. Transport ships can include, for example, cargo ships and containers boat . Furthermore, the marine ship can refer to commercial vessels such as fishing boats, tugboats and supply ships, as well as warships. Furthermore, the marine ship can be used as ferries and submarines.

[0013] Each of the propulsion subsystems 104,104' comprises a foil wheel 106,106', and each of the foil wheels 106,106' comprises at least one foil 108,108'. The foils 108,108' are blades extending downward from the foil wheels 106,106'. At least one of the foils 108,108' is individually controllable and rotatably mounted on the foil wheel 106,106'. Typically, all foils 108,108' are individually controllable and rotatably relative to the foil wheel 106,106'.

[0014] As shown in the example in Figure 1, the wheel engine system 120 may be common to multiple propulsion subsystems 104, 104' via mechanical power transmission.

[0015] Figure 2 shows an example in which the propulsion system 102 has one foil wheel 106. That is, the propulsion system 102 can correspond to one of the propulsion subsystems 104, 104'. Furthermore, the propulsion system 102 includes an actuator device 110 and a controller 112. The controller 112 may be common to all propulsion subsystems 104, 104' (see Figure 1), or the controller 112 may have subcontrollers for each of the multiple propulsion subsystems 104, 104' (such possibilities are shown in Figure 2, but the controller 112 in Figure 2 may be for multiple foil wheels).

[0016] The controller 112 comprises one or more processors 114 and one or more memories 116 containing computer program code. The one or more memories 116 and the computer program code cause the controller 112 to use one or more processors 114 to form data about the pitch angle γ(θ, t) of at least one foil 108 based on the rotation angle θ of the foil wheel 106 to which at least one foil 108 is mechanically connected, and naturally also time-dependent, and an angle-variable wake field W that affects at least one foil 108, the angle dependence of which originates from the rotation angle θ of the foil wheel 106. This can be expressed mathematically as follows: γ(θ(t))=J(θ(t), W(θ(t)) or more simply γ(θ)=J(θ, W(θ)), where J is a function or operation that models the pitch angle γ(θ) of foil 108,108', t is time, and its argument is W(θ(t)), which is the angle of rotation θ of foil wheel 106 and the time-variable wake field W.

[0017] The foil pitch angle γ(θ) is a function of the foil wheel's rotation angle θ and forms a curve, so it is sometimes called the foil pitch trajectory (see Figure 3). The wake field W is on the sea surface. ship The water velocity field can be determined as 100. The wake field W can be thought of as referring to the laminar or turbulent field of water. The wake field W is at least one foil 108 of the same or different foil wheel 106, one or more foils 108, 108', and / or on the sea. ship It can be caused by 100 hulls. Furthermore, the wake field W is at sea. ship It can be caused by underwater currents that have a different source than itself. Underwater currents include rivers, tides, and other sea currents. shipIt can also be generated by wind. Furthermore, underwater flow is variable and, although not a source of flow, can cause a variable wake field W due to the bottom geometry of the underwater surface. In the prior art, models for controlling the pitch angle γ(θ) were not directly related to the underlying physics. By incorporating the wake field W into the model, it is possible to find more realistic control of any foil of the propulsion system 102.

[0018] Next, the controller 112 communicates data regarding the pitch angle γ(θ) to the actuator device 110, and the actuator device sets at least one foil 108 at the pitch angle γ(θ) based on the data formed by the controller 112. The data may include a parameter of the pitch angle and / or at least one value of the pitch angle. The actuator device 110 may include an electric motor device AR for each of the at least one foil 108. The electric motor device AR may include a regulator and an electric motor that rotates the mechanically coupled foil according to the pitch angle γ(θ) from the regulator, which has received data regarding the pitch angle γ(θ) from the controller 112. What has been described for the foil wheel 106 and foil 108 in Figure 2 may also apply to the foil wheel 106' and foil 108' in Figure 1.

[0019] Instead of the cumbersome process of several CFD (Computational Fluid Dynamics) simulations for each operating point and numerical mapping of all model coefficients, the optimal pitch angle can simultaneously yield high efficiency and low lateral force (relative to thrust) in straight-line motion. In other words, both problems can be addressed together. This new routine generates the optimal pitch angle of the foil in the ship's wake, unlike the conventional parametric optimization which is limited to open water conditions only.

[0020] The controller 112 can also control the drive unit 118 of the wheel engine system 120. The wheel engine system 120 may comprise an engine that includes a combustion engine such as an electric engine, diesel engine, gasoline engine or gas engine, and possibly a mechanical gearbox. The controller 112 can send commands to the drive unit 118, which can control the rotational speed and / or direction of rotation of the wheel motor 120. The wheel engine system 120 rotates the foil wheel 106 directly or via the gearbox. However, these kinds of details of the wheel engine system 120 are not very relevant to the actual invention, and those skilled in the art are familiar with the various wheel engine systems 120 themselves. Therefore, they will not be described in more detail here. As shown in the example in Figure 2, each of the propulsion subsystems 104, 104' may have its own wheel engine system 120.

[0021] In one embodiment, the controller 112 is, for example, at sea ship 100 may be connected to at least one sensor 122 that measures the underwater wake field W when operating in the sea, river, or lake. The at least one sensor 122 can then communicate data on the wake field W to the controller 112 by wire or wireless. The at least one sensor 122 is appropriately positioned for at least one foil 108 to measure the wake field W affecting each of the at least one foil 108 as a function of time and position (see also Figure 5 and its description). Based on the values ​​measured by the at least one sensor 122, the controller 112 can form estimates of the wake field W for at least one foil and / or adjacent to at least one foil.

[0022] In one embodiment, the wake field W can be based on a simulation of the water movement around and affecting at least one foil 108, caused by the underwater propulsion system 102 (see also Figure 5 and its description). Thus, the wake field W can be based on a simulation of the water movement around and affecting at least one foil 108, 108', caused by one or more foils 108, 108'.

[0023] As already explained, at sea ship The propulsion system 102 of the 100 can be controlled by a controller 112, which forms data on the pitch angle γ(θ) of at least one foil 108,108' based on the rotation angle θ of the foil wheel 106 and a time-variable wake field W that affects at least one foil 108,108'. The intensity of the wake field W that affects at least one foil 108,108' is position-dependent in addition to time-dependent, and therefore the controller 112 repeatedly or continuously provides new data on the pitch angle γ(θ) to adjust the pitch angle of at least one foil 108,108'. The rotation angle θ of the foil wheel 106 also varies over time as the foil wheel 106 is rotating.

[0024] In one embodiment, the controller 112 can form data relating to the pitch angle γ(θ) of at least one foil 108,108' under the influence of a wake field W at least partially caused by the propulsion of the propulsion system 102. The wake field W may be caused by the foils 108,108' and / or the foil wheels 106,106'.

[0025] In one embodiment, the controller 112 can form data regarding the pitch angle γ(θ) of a foil under the influence of a wake field W at least partially caused by at least one other foil. The at least one other foil and the foil 108 on which the data regarding the pitch angle γ(θ) is formed are mounted on the same foil wheel 106 in this example. Here, the at least one other foil is a different foil from the foil on which the data regarding the pitch angle γ(θ) is formed.

[0026] In one embodiment, the controller 112 is at sea ship Under the influence of the wake field W at least partially caused by the hull 100, data can be formed regarding the pitch angle γ(θ) of at least one foil 108. ship 100 movements, that is, across the sea. ship It also causes the movement of water, such as flow or current, around and adjacent to the 100.

[0027] In one embodiment, the controller 112 is at sea ship Under the influence of a wake field W at least partially caused by 100 environmental factors, data can be formed regarding the pitch angle γ(θ) of at least one foil. The environmental factors are rivers, tides, and at least one other offshore area. ship The wake field W may include at least one of wind and / or the shape of the bottom in the water. The wind does not directly cause any part of the wake field W, but the wind causes the movement of water as a flow or current that can be considered in the wake field W.

[0028] In one embodiment, the controller 112 can generate data relating to the pitch angle γ(θ) for each of the multiple foils 108 that are rotatably mounted on the foil wheel 106 and can be controlled individually. That is, it can control all the foils 108, 108' of the propulsion system 102.

[0029] In one embodiment, the controller 112 can form data relating to the pitch angle γ(θ) of at least one foil 108 under the influence of a wake field W at least partially caused by a plurality of propulsion subsystems 104, 104' of the propulsion system 102, each comprising attached foils 108, 108' including at least one foil.

[0030] In one embodiment, the controller 112 has at least one foil 108 The welcoming Angular α absolute value The maximum rotation of the foil wheel 106 distance Data can be formed regarding the pitch angle γ(θ) of at least one foil 108 while keeping it constant within the tolerance. The term absolute value, also called modulus, refers to the non-negative value of the angle of attack α, regardless of its sign. Mathematically, the absolute value of the angle of attack α can be written as |α|. The tolerance may then be predetermined. The tolerance may, alternatively or additionally, depend on the resolution of the data processing, the mechanical settings, and / or the acceptable mechanical limits, or variations in the limits. The tolerance may be, for example, any combination of these. In one embodiment, the controller 112 sets the angle of attack α of at least one foil 108 to the maximum rotation of the foil wheel 106. distance While maintaining alternative constants with opposite signs, data can be formed for the pitch angle γ(θ) of at least one foil 108. This angle of attack can be applied, for example, to a symmetric square wave target. The angle of attack α may be an estimate formed by the model, or it may be a measured value.

[0031] In conventional technology, the basic pitch angle of the foil is determined by the trochoidal path.

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[0032] A foil profile moving transversely to the incident flow can be considered to have a single angle of attack α that produces peak efficiency. Therefore, in such an embodiment, the data relating to the pitch angle γ(θ) of at least one foil 108,108' is used to maximize the rotation of the angle of attack α of at least one foil 108,108', so that the signs of the angles alternate, as shown in Figure 3 for a smooth square wave target function with respect to the angle of attack α. distance This can be formed while approaching this optimal constant value. In one embodiment, the angle of attack α of at least one foil 108,108' is the maximum rotation distance It is maintained at an optimal constant value for the maximum rotation. In one embodiment, the angle of attack α of at least one foil 108,108' is set to the maximum rotation. distance It is kept within a predetermined range from an optimal constant value for . Maximizing the length may be included in the model function, or the maximization may be caused by a maximizing operator that performs the maximization of the model function. Rotation of the foil wheel 106,106' at a constant mounting angle distance Maximizing this is, in itself, a conventional technique.

[0033] In one embodiment, the optimal angle of attack α yields a peak efficiency of maximum η = 0.9 and can gradually decrease at smaller and higher angles. On the other hand, the angle of attack α obviously cannot be constant throughout the entire foil rotation (360°) of the foil wheels 106,106', but in order to generate positive thrust, the angle of attack α is positive while the foils 108,108' are moving in the positive y-direction (leading side) and negative while the foils 108,108' are moving in the negative y-direction (trailing side). Target angle of attack α target A smooth square wave SSW is proposed for the base shape.

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[0034] Figure 4 shows an example of foil 108 rotating at an angular velocity ω at an arbitrary foil position, expressed as a function of the rotation angle θ of foil wheel 106. The data for the pitch angle γ(θ) of foils 108,108' can be formed such that the target angle of attack α is achieved as close as possible (with a selected amplitude). Mathematically, the situation can be characterized, for example, as follows: Vr=Vin-ωR Vr,x = Vx - ωRx = Vx + ωR*sin(θ) Vr,y = Vy - ωRy = Vy - ωR * cos(θ) β(θ) = atan(Vr, y / Vr, x) γ(θ) = β(θ) - α(θ) In the equation, atan() is the arctangent function, α(θ) is the angle of attack, β(θ) is the relative velocity angle, γ(θ) is the foil pitch angle, Vr is the relative velocity, Vin is the spatially variable inflow velocity of the water, i.e., the wake field W, ωR is the foil velocity, ω is the angular velocity of the foil wheel, and R is the radius of the foil wheel. The inflow velocity Vin relative to the foil wheel and the rotational velocity ωR of the foil around the foil wheel include the relative velocity towards the foil Vr = Vin - ωR. Both Vin, and therefore Vr, are in the ocean. ship Due to the external wake field W from and / or the wake field W induced by the foil itself, the foil wheel Ru rotation angle θIt should be noted that this can be assumed to fluctuate together. This relative velocity forms an angle β(θ) with the x-axis. If the pitch angle of the foil is γ(θ), then the flow angle relative to the foil, i.e., the angle of attack, is given by α(θ) = β(θ) - γ(θ), and the equation becomes γ(θ) = β(θ) - α(θ). Writing the relative velocity flow angle β(θ) and the (symmetric) target angle of attack α(θ), the pitch angle γ(θ) of foils 108,108' can be written as follows.

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[0035] While measurement using at least one sensor 122 may be possible, the fact that not only the wake field W but also the angle θ of the foil wheels 106,106' at the exact same moment is required as a function θ can make this difficult. In one embodiment, the contribution of the wake field W can be recorded from a CFD simulation. This can be achieved by positioning the computational probe 500 adjacent to the foils 108,108' so that the foils 108,108' follow the rotation of the foil wheels 106,106'. In one embodiment, the computational probe may not pitch the foil and may remain stationary relative to the pivot point of the foil it follows. In this embodiment, the vector pointing the probe from the pivot point is always parallel to the x-axis. An example of positioning the computational probe 500 at different foil positions is shown in Figure 5.

[0036] The distance DD between the probe 500 and the adjacent corresponding foil 108 can be such that the probe 500 is not too close to the foil 108 so that the foil itself significantly disturbs the flow adjacent to the probe, and not too far so that a high correlation remains between the velocity of water movement in the probe 500 and the adjacent foil. In one embodiment, a suitable distance DD may be about 3 / 4 of the length of the chord ahead of the pivot point. More generally, the range of distance DD may be, for example, about 0.5 to about 1 chord length. In principle, the wake field W should be expressed over the span of the foil (average in the z direction), but for simplicity, it can be assumed that a single point approximately in the center is sufficient. When the wake field W is measured, at least one sensor 122 can be placed at the corresponding position as the calculation probe 500.

[0037] The contribution of the wake field W can have a very complex shape.

[0038] In one embodiment, the contribution of the wake field W can be continuously iterated within a CFD simulation. The control system, in particular a PID (proportional-integral-derivative) control system, requires a continuous analysis function having at least one continuous derivative. If the wake field W is collected from the CFD simulation or from measurements performed by at least one sensor 122 at intervals of Δθ = 1°, i.e., at all degrees of the 360° rotation of the foil wheel 106,106', a good model based on a continuous trigonometric function having a total of 360 (full rotation) terms for each wake contribution can be formed using the discrete Fourier transform.

[0039] However, supplying such a quantity of data on the wake field W to the control system of an actual machine can be impractical. Furthermore, the actual wake field W may not be identical to the simulation in all details. Therefore, in one embodiment, only a constant mean term and / or a few lowest frequency sine and cosine terms can be retained from the Fourier series representation of the wake field contribution. For example, three lowest frequency sine and cosine terms may suffice. These truncated functions can then be processed in the controller 112, for example, according to equation (2A) or (2B). Based on this type of algorithm, the controller 112 can form data regarding the foil pitch angle in the new CFD simulation. Since the wake field W also depends on the foil pitch angle, this can be done iteratively in one embodiment. The iterative process can be carried out as follows: 1) The pitch angle of the foil in equation (2B)

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[0040] In step 7), the new iteration pitch function was measured.

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[0041] In one embodiment, the angle of attack α(θ) is kept constant for the maximum length around the rotation of the foil wheel 106,106', and the data for the pitch angle γ(θ) is iterated for a single design point (velocity and RPM), but the contribution of the wake field W is considered.

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[0042] However, this behavior can also be improved in one embodiment. Here, the scaled downstream field

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[0043] Since disturbance-free velocity and RPM can be easily obtained, the disturbance-free contribution of the wake field is also easily achieved.

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[0044] This is the scaled induction contribution of the wake field W.

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[0045] The angle of attack α(θ) is constant along the maximum length of rotation of the foil wheel 106,106', but the foil pitch angle can reduce lateral force. In one embodiment, it is possible to modify the target angle of attack α(θ) to adjust the lateral force to zero or a large value. In one embodiment, at sea ship To steer the vehicle to rotate 100, the lateral force can be adjusted to a large value. However, from a steering perspective, it may be desirable for the propulsion system 102 to have zero or only a weak lateral force in a straight line. Both instantaneous thrust and lateral force depend on the corresponding angle of attack α(θ). When the angle of attack α(θ) is significantly below the stall angle, both increase.

[0046] For example, at a constant angle of attack of ±15°, the net lateral force is positive, and the positive net lateral force decreases by increasing the leading angle of attack (approximately θ = 0 / 360°) or decreasing the trailing angle of attack (approximately θ = 180°). Therefore, instead of a symmetric constant angle of attack, an asymmetric constant angle of attack, as in equation (1), can be inserted into equations (2A) or (2B), for example, A = 14° and B = 1°. An asymmetric smooth square wave is obtained at approximately constant values ​​of +15° on the leading side and -13° on the trailing side (see Figure 3). The rotational speed can be increased to compensate for the thrust loss due to the small trailing angle of attack. These settings allow for the iterative process of obtaining an approximate wake field W to be repeated. Target angle of attack α(θ) target Figure 6 shows an example of the actual angle of attack α(θ) obtained as a result of having instantaneous foil efficiency. Here again, the actual angle of attack α(θ) is the same as the target angle of attack α(θ). targetIt follows very well and maintains a high level of efficiency. The performance results behave as expected. In this optimization example, efficiency is further improved and lateral force is reduced compared to the conventional technology. However, thrust is slightly reduced. The reduced thrust can be compensated for by further increasing the rotational speed or by slightly reducing the asymmetry, for example by adjusting A=14.1 and B=0.9°. The main performance coefficients for this asymmetrical constant angle of attack of +15° / -13° are listed in Table 1. For reference, the corresponding performance coefficients for the symmetrical constant angle of attack of +15° / -15° are listed in Table 2. [Table 1]

[0047] In Tables 1 and 2, P represents power, Fx and Fy represent forces in the orthogonal x and y directions, η represents the efficiency of the propulsion system, D represents the diameter of the foil wheel, RPM represents the revolutions per minute of the foil wheel, and α represents the angle of attack. [Table 2]

[0048] By optimizing the pitch angle γ(θ) using the wake field W, both high efficiency and low lateral force are achieved when traveling in a straight line.

[0049] By including a local variable wake field W, it becomes possible to achieve very high efficiencies, even around 85%. In addition to formulating a constant angle of attack, similar efficiency levels can be achieved by expressing the pitch function γ(θ) as a series of periodic functions and optimizing the coefficients using the local variable wake field W as input to the optimization. In this way, the underlying physics can be more broadly related to the optimization, thereby enabling higher efficiencies to be achieved more generally.

[0050] As an example of optimizing the pitch angle γ(θ), it can also be expressed in mathematical form as follows: The pitch function parameters are X=(X1,...,XN ) is represented by, which can be considered as data related to the pitch angle. The objective function is represented by E, and the constraint function is represented by C. The parameter X, the objective function E, and the constraint function C can be considered as vectors when the controller 112 executes the algorithm. The optimization problem can be described as follows.

[0051] The objective function is maximized or optimized using the Max operator, Max E(X). The constraint function is C U ≧C(X)≧C L subject to the constraint that, where C U and C L are the upper and lower limits of C, respectively.

[0052] The pitch function parameter is subject to the following constraint: X L ≦X≦X U where X L and X U are the lower and upper limits of X, respectively.

[0053] Here, the objective function E and the constraint function C relate to foil foil wheel performance variables such as thrust, lateral force, and efficiency. The optimization goal can be to maximize efficiency (E) with a constraint on thrust (C), or to maximize thrust (E) with an efficiency (C) greater than a set value.

[0054] The pitch angle γ(θ) can be calculated from the pitch function parameter X, i.e., γ(θ)=f(X), where f(X) is a periodic function of the angular position θ having k continuous derivatives, and has a smooth curve when k≧2, and avoids sudden changes in blade orientation considering the moment limit of the blade motor. The periodic function f(X) can be represented, for example, using at least one spline function. A spline function is a function that can be defined piecewise by polynomials. The periodic function f(X) can include, for example, at least one elementary function that is at least twice differentiable.

[0055] If the wake field W is included in the optimization, the optimization problem can be performed as follows: The objective function E is maximized or optimized using the Max operator Max E(X,W). The constraint function is C U ≥C(X)≥C L Subject to the restriction, in the formula, C U and C L These are the upper and lower limits of C, respectively. U ≥C(X)≥C L And in the formula C U and C L These are the upper and lower limits of C, respectively. The limits of the pitch function parameters depend on the final operating conditions and application. For example, in the case of operation like that of a typical trochoid, the derived angle of attack should be limited from the stall mode.

[0056] In one embodiment, the controller 112 can generate data relating to the pitch angle γ(θ) by optimizing the efficiency and / or thrust of a model formed from a set of quadratic continuous periodic functions of the pitch angle γ(θ), which have the angle of attack α and the wake field W as its arguments, with or without operational requirements and / or constraints. A quadratic continuous periodic function refers to a function having first and second derivatives.

[0057] In one embodiment, the controller 112 can generate data relating to the pitch angle γ(θ) by maximizing the efficiency and / or thrust of a model formed from a set of quadratic continuous periodic functions of the pitch angle γ(θ).

[0058] In one embodiment, the controller 112 is, for example, at sea ship 100 positions, other seas shipThe controller 112 may receive or have available data regarding wind conditions and / or tides, and may utilize the received data in forming the pitch angle γ(θ). Location data may include information about flows caused by nearby rivers and / or a map of the riverbed at that location, and the controller 112 may estimate the wake field W based on at least one of these. The controller 112 may additionally or alternatively estimate the wake field W based on wind and / or tidal conditions.

[0059] As explained above, a pitch angle γ(θ) is formed, but this pitch angle γ(θ) is unprecedented, enabling the achievement of optimal hydrodynamic performance. Figure 7 shows an example of the foil's pitch angle trajectory with respect to the rotation angle of the foil wheel at an arbitrary but common scale. The x-axis represents the rotation angle θ of the foil wheel, and the y-axis represents the pitch angle γ. It can be seen that the novel method described herein can result in a trajectory different from the conventional cycloid foil pitch trajectory.

[0060] Figure 8 is a flowchart of the control method. In step 800, the controller 112 forms data relating to the pitch angle γ(θ) of at least one foil 108,108' rotatably mounted on the foil wheel 106,106', which is individually controllable, based on the angle variable wake field W(θ) affecting at least one foil 108,108' and the rotation angle θ of the foil wheel 106,106'. In step 802, at least one foil 108,108' is set to the data-based pitch angle γ(θ) by the actuator device 110 which receives data from the controller 112.

[0061] The method shown in Figure 7 can be implemented as a logic circuit solution or a computer program. The computer program can be placed in a computer program distribution means for distribution. The computer program distribution means is readable by a data processing device, encodes computer program commands, performs measurements, and optionally controls processes based on those measurements.

[0062] Computer programs may be delivered using a delivery medium, which may be any medium readable by the controller. The medium may be a program storage medium, memory, a software delivery package, or a compressed software package. In some cases, delivery may be performed using at least one of near-field communication signals, short-range signals, and telecommunication signals.

[0063] Improvements and advantages in the formation of the foil trajectory's pitch angle as a function of the wake field W may include: an angle of attack that can be kept constant or within a certain range with respect to the maximum length of rotation of the foil wheel during pitch angle formation. 1) Highly efficient gain up to η=0.85, 2) By being directly related to physics (wake field), unlike parametrically optimized pitch trajectories, design point parameters can be used throughout the entire operating range. 3) While the optimal performance of a parametrically optimized trajectory is limited to open water conditions, a trajectory with a constant angle of inclination is available when the wake field used is recorded from CFD simulation or measurements in the open water. ship To be optimal 4) Asymmetric angle of attack α during straight-line operation target The ability to adjust lateral force to zero without loss of efficiency. 5) Avoiding thrust and efficiency losses induced by flow separation / stall (angle of attack is controlled), 6) The "high thrust" mode is simply the angle of attack α target This is achieved by increasing the amplitude (without exceeding the stall angle).

[0064] As technology advances, it will be apparent to those skilled in the art that the concept of the present invention can be implemented in a variety of ways. The present invention and its embodiments are not limited to the exemplary embodiments described above and can be modified within the scope of the claims.

Claims

1. A method for controlling the propulsion system (102) of a surface vessel (100), Step (800) of forming data relating to the pitch angle (γ(θ)) of the at least one foil (108, 108') rotatably mounted on the foil wheel (106, 106'), based on an angular and temporally varying wake field (W(θ)) affecting the at least one foil (108, 108') which is a blade and individually controllable, and the angle (θ) of rotation of the foil wheel (106, 106'), wherein the wake field W(θ) is determined by simulation or measurement and decomposed into an undisturbed contribution and an induced contribution that is locally constant with respect to θ but varies with respect to θ, and the pitch angle (γ(θ)) is formed such that the angle of attack (α) of the at least one foil (108, 108') is constant or maintained within tolerance over the maximum rotation distance of the foil wheel (106, 106'), Step (802) of setting the at least one foil (108, 108') with the pitch angle (γ(θ)) based on the data by an actuator device (110) that receives the data from the controller (112) A method characterized by the following.

2. The method according to claim 1, characterized in that the data relating to the pitch angle (γ(θ)) of the at least one foil (108, 108') is formed under the influence of the wake field (W) caused by the propulsion of the propulsion system (102).

3. The method according to claim 2, characterized in that the data relating to the pitch angle (γ(θ)) of the foil of the at least one foil (108) is formed under the influence of the wake field (W) caused by at least one other foil (108) different from the foil on which the data relating to the pitch angle is formed, wherein the at least one foil (108) is mounted on the foil wheel (106) on which the foil on which the data relating to the pitch angle is formed is also mounted.

4. The method according to claim 1, characterized in that the data relating to the pitch angle (γ(θ)) of the at least one foil (108) is formed under the influence of the wake field (W) generated by the hull of the maritime vessel (100).

5. The method according to claim 1, characterized in that the data relating to the pitch angle (γ(θ)) of the at least one foil (108) is formed under the influence of the wake field (W) caused by the environment of the marine vessel (100).

6. The method according to claim 1, characterized in that the data relating to the pitch angle (γ(θ)) is formed for each of a plurality of foils (108) that are individually controllable and rotatably mounted together with the foil wheel (106).

7. The method according to claim 1, characterized in that the data relating to the pitch angle (γ(θ)) of the at least one foil (108, 108') is formed under the influence of the wake field (W) caused by a plurality of propulsion subsystems (104, 104') of the propulsion system (102), wherein the propulsion subsystem (104, 104') comprises a foil (108, 108') attached to the propulsion subsystem (104, 104'), which includes the at least one foil (108, 108').

8. The method according to claim 1, characterized in that the wake field (W) is based on a simulation of the propulsion system (102) in water.

9. The method according to claim 1, characterized in that the wake field (W) is measured by at least one sensor (122) when the surface vessel (100) is in the water, and data relating to the wake field (W) is communicated to the controller (112).

10. The method according to claim 1, characterized in that the data relating to the pitch angle (γ(θ)) of the at least one foil (108, 108') is formed while keeping the absolute value of the angle of attack (α) of the at least one foil (108, 108') constant within the tolerance of the maximum rotation distance of the foil wheel (106, 106').

11. The method according to claim 1 or 10, characterized in that the data relating to the pitch angle (γ(θ)) of the at least one foil (108, 108') is formed while maintaining the angle of attack (α) of the at least one foil (108, 108') to two alternative constants having opposite signs within the tolerance of the maximum rotational distance of the foil wheel (106, 106').

12. The scaled wake field is decomposed into the sum of the undisturbed contribution and the additional contribution induced by the foil (108, 108'), Setting the induced scaled contribution caused by all foils (108, 108') to constant, Based on locally constant induced scaled contributions, an approximate value of the wake field (W) is determined. The method according to claim 1, characterized by the above.

13. The method according to claim 1, characterized in that the data relating to the pitch angle (γ(θ)) is formed by optimizing the efficiency and / or thrust of a model formed from a set of quadratic continuous periodic functions of the pitch angle (γ(θ)), angle of attack (α), and wake field (W), regardless of the presence or absence of operational requirements and / or constraints.

14. A propulsion system (102) for a maritime vessel (100), The propulsion system (102) is characterized by comprising foil wheels (106, 106'), at least one foil (108, 108') that is rotatably mounted on the foil wheels (106, 106') and is a blade that can be individually controlled, an actuator device (110), and a controller (112). The controller (112) comprises one or more processors (114) and one or more memories (116) containing computer program code. The one or more memories (116) and the computer program code are configured to use the one or more processors (114) to cause at least the controller (112) to form data relating to the pitch angle (γ(θ)) of at least one foil (108, 108') based on the rotation angle (θ) of the foil wheel (106, 106') and the angular and temporally changing wake field (W(θ)) affecting at least one foil (108, 108'), and to communicate the data relating to the pitch angle (γ(θ)) to the actuator device (110) which is configured to set the at least one foil (108, 108') with the pitch angle (γ(θ)) based on the data. The wake field W(θ) is determined by simulation or measurement and decomposed into an undisturbed contribution and an induced contribution that is locally constant with respect to θ but varies with respect to θ, and the pitch angle (γ(θ)) is formed such that the angle of attack (α) of at least one foil (108, 108') is constant or maintained within tolerance over the maximum rotational distance of the foil wheel (106, 106'). Propulsion system (102).

15. A maritime vessel (100) characterized by being equipped with the propulsion system described in claim 14.

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