Ship motion control based on propeller slippage

Abstract

A control system (140, 600, 1100) for controlling at least one vessel drive unit (110) on a vessel (100), the control system (140, 600, 1100) being configured to obtain data indicative of a water speed STW (VW, VA) of the vessel (100), the control system (140, 600, 1100) being configured to determine a propeller slip (lambda) of the at least one vessel drive unit (110) based on a propeller speed ([omega] p) of the drive unit (110) and a water speed (VW) of the vessel (100), wherein the control system (140, 600, 1100) is configured to obtain a relationship (400) between the drive unit thrust (Fx) and the propeller slip (lambda), and wherein the control system (140, 600, 1100) is configured to obtain data indicative of a desired thrust to be generated by the drive unit (110), and determining a target propeller slip corresponding to the desired thrust based on a relationship (400) between the drive unit thrust (Fx) and the propeller slip (Lambda), the control system (140, 600, 1100) being arranged to control a propeller speed (Omega p) of the vessel drive unit (110) to produce the target propeller slip and to maintain the propeller slip (Lambda) below a predetermined propeller slip limit (Lambda lim).

Description

Technical Field

[0001] This disclosure generally relates to the motion control of vessels such as recreational boats and small merchant ships. In a particular aspect, this disclosure relates to computer-implemented methods for propulsion control and general motion management of vessels. Control input devices for electric ship drive units are also disclosed. Although this disclosure may be described with reference to specific vessels, it is not limited to any particular type of boat or vessel. Background Technology

[0002] Vessels such as recreational boats and small merchant ships can be powered by one or more propellers. These propellers are driven by corresponding power sources, such as combustion engines or electric motors. For both sustainability and cost reasons, the energy efficiency of ship propulsion systems is becoming increasingly important. Comfort is another important aspect, particularly regarding noise and vibration.

[0003] Both US20020185046A1 and WO2008155448A1 describe a ship propulsion unit control system that implements a function to limit the propeller slip of the propulsion unit below the propeller slip limit. This allows control over negative effects caused by, for example, cavitation.

[0004] Despite the much work that has been done so far, there is still a desire for ship propulsion systems that are both energy-efficient and provide a comfortable sailing experience. Summary of the Invention

[0005] A control system for controlling at least one ship propulsion unit on a vessel is disclosed, which seeks to alleviate one or more of the problems mentioned above. The control system is configured to acquire data indicating the ship's surface speed (STW), such as the surface speed of the ship's hull and / or the surface speed of one or more propellers. The control system is also configured to determine the propeller slip of the ship propulsion unit based on the propeller rotational speed of the propulsion unit and the surface speed of the ship and / or propellers. The control system is further configured to: acquire a relationship between the propulsion unit thrust and the propeller slip; acquire data indicating the desired thrust to be generated by the propulsion unit; and determine a target propeller slip corresponding to the desired thrust based on the relationship between the propulsion unit thrust and the propeller slip. The control system then controls the propeller rotational speed of the ship propulsion unit to generate the target propeller slip, thereby providing the desired thrust. This method of controlling the propulsion unit enables more efficient propulsion and also allows for a more consistent response behavior of the ship to thrust commands at different ship speeds.

[0006] For example, the control system can be configured to obtain the relationship between drive unit thrust and propeller slip in the form of a predetermined analytical function or a predetermined set of analytical functions. The relationship between drive unit thrust and propeller slip can also be pre-configured as a lookup table (LUT), and in some cases, the LUT can be used as a supplement to one or more predetermined analytical functions.

[0007] The control system described herein is also arranged to control the propeller speed of the ship's drive unit to maintain propeller slip below a predetermined propeller slip limit. This means that the drive unit always operates at a speed not associated with excessive propeller slip, which is generally an inefficient operating mode that should be avoided. Therefore, aspects of this disclosure seek to ensure that the ship's drive unit does not operate at excessively high propeller slip, where, for example, cavitation adversely affects performance and generates unwanted noise and vibration. Since excessive cavitation is avoided in this way, the technology disclosed herein also reduces propeller wear. The control system disclosed herein provides energy-efficient and comfortable propulsion. The propeller slip limit is preferably configured such that a further increase in propeller slip does not result in any significant increase in propeller thrust. Thus, the drive unit implements propulsion power rollback from an inefficient high-power operating point (where increasing power only results in an increase in propeller slip without a significant increase in propeller thrust).

[0008] This disclosure also relates to a control unit that maps operator thrust input commands to corresponding propeller slippage via a relationship between drive unit thrust and propeller slip. This allows the operator to experience a more consistent response from the vessel to thrust commands, less dependent on the vessel's current speed relative to the water.

[0009] According to some aspects, the ship's drive unit includes an electric motor arranged to provide a target shaft speed upon request from the control system. The control system disclosed herein is particularly advantageous for use with an electric motor capable of adjusting the shaft speed with low latency and high control bandwidth (i.e., responding quickly and accurately to requests to change the shaft speed). Therefore, regardless of disturbances caused by changes in sea and wind conditions, the propeller speed can be maintained close to the target propeller speed.

[0010] For example, the control system can be configured to receive data indicating speed relative to water from a speed log deployed on the vessel. Speed ​​logs are typically present as part of the standard sensor setup on most vessels. The advantage is that the techniques disclosed herein can be implemented without the need for additional sensors, which would increase cost and system complexity. However, other data sources can also be used to receive data indicating speed relative to water. Ground speed data from a GPS system deployed on the vessel and / or from a sonar sensor system can, for example, be used to determine or at least estimate the vessel's speed relative to water.

[0011] According to some aspects, the control system is arranged to control multiple ship propulsion units on the vessel, such as a port propulsion unit and a starboard propulsion unit, or two or more propulsion units. In this case, the control system can be configured to obtain data indicating the velocity relative to the water for at least two of the multiple propulsion units, and thus determine the individual propeller slip of the propulsion units. When there are two or more propulsion units, this improves the accuracy of propeller slip control because the two or more propulsion units may be traveling at different velocities relative to the water, for example, when the vessel is turning. The control system can also optionally be arranged to control the port and starboard propulsion units in such a way that the propeller slip limits for the outer propulsion units performing turning maneuvers in the port and starboard propulsion units are configured to be lower than the propeller slip limits of the inner propulsion units performing turning maneuvers in the port and starboard propulsion units. Due to the rolling motion caused by turning, the outer propulsion units can operate at a reduced draft, and therefore may be more sensitive to cavitation development compared to the inner propulsion units operating at a draft greater than the nominal draft. These aspects can also be considered when controlling propeller slip, for example, by reducing the propeller slip limit of the outer drive unit compared to the propeller slip limit of the inner drive unit during cornering maneuvers.

[0012] According to some aspects, the control system is arranged to control a ship drive unit with an adjustable propeller pitch. In this case, the control system can be arranged to control the propeller speed and propeller pitch of the ship drive unit based on a predetermined relationship between efficiency, motor shaft speed, and applied torque of the motor to generate a target propeller slip. This allows for further improvement in propulsion efficiency, which is an advantage. Given a desired propeller thrust and the ship's velocity relative to the water, the control system can determine the desired propeller slip (based on the relationship between propeller thrust and propeller slip), thereby controlling both the propeller speed and pitch to obtain an efficient drive unit operating point.

[0013] The control system may also include a centralized vessel motion management (VMM) module, which is arranged to request propeller slip from at least one motion support device (MSD) control module. If the desired maneuver can be achieved in more than one manner using more than one drive unit, the centralized VMM module or function can perform further optimizations. For example, steering of a multi-drive unit vessel can typically be achieved using propeller angles (drive units navigating at different azimuth angles) and thrust differentials that generate yaw motion.

[0014] A centralized VMM module can dynamically adjust the configured propeller slip limits during turning maneuvers. For example, a centralized VMM module can be configured to automatically increase the propeller slip limits of the outer propeller compared to the inner propeller during turning maneuvers due to draft differences. This allows for propeller speed adjustment when the vessel is turning.

[0015] The foregoing aspects, the appended claims, and / or the examples disclosed herein above and below can be appropriately combined with each other, as will be apparent to those skilled in the art.

[0016] Further features and advantages are disclosed in the following description, claims, and drawings, and will be apparent in part to those skilled in the art or may be recognized by practicing this disclosure as described herein. Control units, computer systems, computer-readable media, and computer program products associated with the technical benefits discussed above are also disclosed herein.

[0017] This disclosure also relates to a control input device for controlling a ship's drive unit. The control input device is arranged to receive, for example via a joystick or lever mechanism, an input command from an operator indicating a desired ship speed or acceleration to be generated. The control input device then converts the input command into an equivalent propeller slip value, and then uses said equivalent propeller slip value to control the propeller speed based on the ship's current relative speed to the water. Attached Figure Description

[0018] The various aspects of this disclosure, cited as examples, are described in more detail below with reference to the accompanying drawings.

[0019] Figure 1 An example ship is shown.

[0020] Figure 2 The pitch of the propeller has been explained.

[0021] Figure 3 It is a graph showing the relationship between tire slippage and the forces generated by the tires of road vehicles.

[0022] Figure 4This is a diagram illustrating an exemplary relationship between propeller slip and force.

[0023] Figure 5 This is a diagram showing exemplary speeds and propeller slip during ship startup.

[0024] Figure 6 Exemplary components of a ship propulsion system are schematically shown.

[0025] Figure 7 An aspect of an exemplary ship control system is illustrated schematically.

[0026] Figure 8A A vessel with two drive units is shown during yaw maneuvers.

[0027] Figure 8B The ship's speed and propeller slip are shown during yaw motion.

[0028] Figure 9 This illustrates the relationship between torque, speed, and efficiency of an electric motor.

[0029] Figure 10 An exemplary drive unit throttle control device is shown.

[0030] Figure 11 This is a schematic diagram of an exemplary computer system.

[0031] Figure 12 An exemplary computer program product is shown, and

[0032] Figure 13 This is a flowchart illustrating the method. Detailed Implementation

[0033] This disclosure will now be described more fully below with reference to the accompanying drawings, which illustrate exemplary embodiments. However, this disclosure may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided for thoroughness and completeness. Similar reference numerals throughout this specification refer to similar elements. The aspects set forth below are intended to enable those skilled in the art to practice the information necessary for the present disclosure.

[0034] Figure 1 A vessel 100 is schematically illustrated, in this example a vessel powered by two drive units 110 attached to the stern plate of the hull 120 of the vessel 100. Each drive unit includes a propeller assembly 130. The propeller assembly of the drive unit 110 discussed herein may be, for example, a single propeller assembly or a twin propeller assembly (commonly referred to as a twin propeller assembly). Figure 1The propeller assembly 130 is a twin-propeller assembly. This disclosure is not limited to any particular type of vessel, nor to any particular type of propeller assembly. The teachings herein can be applied to outboard and inboard drive units, as well as pull and push propellers. The drive unit can be as follows: Figure 1 The drive unit is attached to the stern plate of the vessel 100, or extends downward from the underside of the hull 120. The drive unit can be rotatable, i.e., providing steering functionality, or fixed relative to the hull 120 for steering.

[0035] Electric motors and hybrid power systems are becoming increasingly common on ships. The advantage of electric motors is the ability to quickly and precisely control the shaft speed of the drive unit. Another advantage is that electric motors allow for very rapid changes in applied torque. Generally, if the propeller is driven by an electric motor or a hybrid electric drive unit, the propeller speed can be adjusted very quickly and with high precision.

[0036] The forward direction of vessel 100 is referred to as the x-direction in this paper, while the transverse direction perpendicular to the forward direction is referred to as the y-direction. The vertical direction is the z-direction, which is orthogonal to both the x and y directions. The velocity of vessel 100 in the forward or longitudinal direction is referred to as... , while lateral velocity is called The yaw motion about the z-axis will be called... ,like Figure 1 As shown.

[0037] The speed of the vessel 100 relative to water can be measured by the vessel control unit 140 using a speed log 150. Several different types of vessel speed logs are known, such as electromagnetic logs, Doppler logs, impeller logs, Pitot logs, and acoustic correlation logs.

[0038] A ship's speed relative to water can be purely longitudinal, but it is very likely that there is also some drift involved, meaning that the speed includes not only longitudinal velocity but also other components. In addition to quantity, there is also Component. When discussing propeller slip, what is usually important is the velocity of the water flow through the propeller along the propeller axis. For a given drive unit, the velocity of the water along the propeller axis is referred to here as... This speed yes , and The thrust angle is a function of the steering angle of the ship's propulsion unit. If the drive unit is a steering (rotatable) drive unit, it is also a function of the steering angle of the ship's propulsion unit. The drive unit can also have a pitch angle, i.e., the thrust direction is separated from the horizontal plane by a certain angle. This disclosure can be directly extended to non-zero pitch angles. Speed Usually can be done It is a good approximation, and in many cases can also be approximated by ground velocity, which can be obtained, for example, by a satellite positioning system receiver or a sonar system.

[0039] Figure 2 A single propeller 200 with a diameter D and a pitch P is schematically shown. The pitch P is the distance the propeller travels when it enters an imaginary solid medium. The rotational speed of the propeller is represented by... express.

[0040] Longitudinal wheel slippage of tires on road vehicles such as trucks or cars Can be defined as

[0041] in This is the effective radius of the wheel, in meters. Let x be the angular velocity of the wheel (where the subscript x indicates that the wheel typically travels in the longitudinal direction); and Let F be the longitudinal velocity of the wheel in the wheel coordinate system (relative to the road). Wheel slip is essentially the measured velocity difference between the wheel and the vehicle. Wheel slip increases if the acceleration of the wheel's rotational motion is greater than the acceleration of the vehicle on the road surface. Wheel slip is positive during acceleration and negative during braking. Slip must occur for the wheels or tires on a road vehicle to generate tire forces. This applies to both acceleration and braking. For small slip values, since the tire contact patch is in a state of full adhesion and no slippage occurs, the relationship between wheel slip and the generated force is approximately linear, where the proportionality constant is usually expressed as the tire's slip stiffness. The normal force F acting on the wheel is the tire's normal force. z It is crucial for determining some important vehicle properties. For example, the normal force largely determines the longitudinal tire force F that the wheel can achieve. x Because usually, in It is the coefficient of friction associated with the current road friction conditions.

[0042] The inverse tire model is a model of wheel behavior that describes the tire force generated in the longitudinal direction of the rolling direction as a function of wheel slip. Figure 3 Figure 300 illustrates an example of how tire force varies with longitudinal wheel slip λ. (Longitudinal tire force) The diagram shows a portion 310 where wheel slip increases almost linearly under smaller wheel slip, followed by a portion 320 exhibiting more non-linear behavior under larger wheel slip. In this portion, part of the contact patch slides relative to the road surface. It should be noted that a peak 330 exists beyond which tire force decreases with wheel slip; that is, if the wheel speed increases beyond a given wheel speed, the generated tire force will decrease. The primary reason for this decrease in characteristics is that sliding friction is lower than static friction. Controlling a road vehicle in zone 320 can be difficult and is therefore often avoided, and is also undesirable from both an energy efficiency and tire wear perspective. Operating within zone 320 is also generally associated with reduced passenger comfort in road vehicles. Therefore, wheel slip limits are typically imposed. This is to ensure that the wheels do not operate in the unwanted area 320, at least not for extended periods.

[0043] longitudinal slip of the propeller It can be defined similarly to the longitudinal slip of tires on a road vehicle, that is, the difference between the propeller pitch P divided by the time of one revolution and the propeller's velocity against the water (STW) along the propeller axis. In other words, if the ship is traveling forward in a straight line, then... If the ship is in motion, then it is and The combination of [various parameters]. The propeller's velocity relative to the water under no-slip conditions ([various parameters]). The propeller speed is calculated by considering the propeller as a screw screwed into a solid medium, i.e., the pitch P divided by the time it takes for the propeller to complete one revolution. .

[0044] If the propeller accelerates, the slip increases, and vice versa. Propeller slip can be positive (during acceleration) and negative (during deceleration). Other alternative definitions of propeller slip with the same or similar effects can be used, such as discrete approximations of the expression above.

[0045] It has been recognized that for many combinations of propeller and hull shapes, there exists a relationship between propeller thrust and propeller slip. Figure 3A similar relationship exists. As the propeller accelerates, propeller slip increases and it begins to generate thrust. Initially, thrust increases with propeller slip, meaning the greater the propeller slip, the greater the thrust. Similarly, this is similar to the situation with tires on road vehicles—without propeller slip, there is no thrust on the hull of a ship. However, once propeller slip exceeds a critical point, cavitation begins to form, and a situation similar to the nonlinear region 320 arises, where faster propeller speeds lead to decreased thrust (or at least a decreased thrust coefficient) and / or increased discomfort due to noise and vibration. Cavitation-induced propeller wear also occurs when propeller slip exceeds a given value.

[0046] Because ship propellers rotate at an angle of attack in the water, each blade of the propeller generates a pressure side and a suction side. The faster the blade cuts into the water surface, that is, the faster it rotates relative to the stochastic oscillation (STW), the lower the pressure on the suction side of the blade. At a specific propeller speed relative to the STW, the pressure on the suction side becomes so low that the water flowing through that area evaporates, forming bubbles or voids. When this happens, the propeller's operating efficiency begins to decline.

[0047] Cavitation can have a significant impact on propulsion performance. It typically begins at the blade tip and gradually spreads throughout the blade as propeller load increases. When cavitation extends to approximately 0.75 times the radius, a considerable loss of thrust is observed, followed by a decrease in torque, which effectively means a significant increase in rotational speed for a given power output. Since thrust decays faster than torque changes, efficiency can suffer a substantial loss. Noise and vibration are other adverse effects caused by cavitation becoming too pronounced.

[0048] Figure 4 Some exemplary relationships between thrust (i.e., propulsion force) and propeller slip are shown, which can be seen in some propeller designs and hull shape combinations. There exists an approximately linear region 410, where an increase in propeller speed results in an increase in propeller thrust. If the propeller speed relative to the ship's water velocity increases beyond this range, a peak range 420 is entered, where the propeller operates at peak efficiency. Beyond this range, region 430 can be seen, where an increase in propeller speed is detrimental to both propulsion and energy efficiency.

[0049] In the first example 440, regardless of how much the propeller speed increases, the thrust increases with propeller slippage until a point where no more thrust can be obtained. In this case, increasing the propeller speed beyond a certain point is meaningless, as the additional increase only leads to inefficiency and often causes discomfort manifested as noise and vibration. In region 430, propeller wear may also increase.

[0050] In the second example 450, the propeller design and hull shape together cause the thrust to increase approximately linearly with increasing propeller speed until cavitation begins to become significant enough to adversely affect the thrust. If the propeller rotates faster relative to the surrounding water, the thrust will begin to decrease.

[0051] In the third example 460, the cavitation effect is even more pronounced. In this case, the combination of propeller design and hull shape leads to catastrophic cavitation, resulting in an almost complete loss of propulsion.

[0052] In all examples, the noise and vibration generated were relatively small at first, then increased sharply as the propeller slip reached sufficiently high values.

[0053] It is worth noting that there is a propeller slip limit in each case. Below the propeller slip limit, operation is expected to be efficient and predictable; beyond this limit, operation may become more unpredictable and less efficient, with more noticeable noise and vibration. Therefore, for every combination of propeller design and hull shape, there exists a desired propeller slip operating range, exceeding which leads to inefficient operation and / or discomfort.

[0054] As mentioned, the relationship between thrust and propeller slip depends on many factors, such as propeller design, hull shape, temperature, air pressure, and sea state. However, an approximate relationship between propeller thrust and propeller slip can usually be established directly through computer simulation, mathematical analysis, and / or actual experiments. Different amounts of propeller slip can be generated, and thrust can be measured for each propeller slip value. The measured and / or simulated thrust levels can then be plotted against the propeller slip values ​​to obtain, for example, Figure 4 The relationships shown are related.

[0055] It has been recognized that some ship drive units can be better controlled based on propeller slip or propeller speed relative to the STW (Speed ​​Transmission Wing) compared to currently more or less popular control methods based on propeller shaft torque. At least, significant advantages can be gained by implementing propeller slip limits, which prevents the ship drive unit from operating when the propeller slip exceeds a predetermined slip limit. This is because operation exceeding the slip limit rarely provides any benefit to ship maneuvering, propulsion efficiency, or wear on drive components. Therefore, this disclosure proposes a control system 600 and a corresponding method for controlling a ship drive unit 110 on a vessel 100 (such as a recreational boat or a smaller commercial vessel, i.e., a ferry, a small cargo ship, etc.). The control system 600 is configured to obtain an indication of the vessel 100's speed relative to the water. The data. STW can be obtained using a conventional speedometer and / or via other means (such as a GPS receiver as mentioned above). The relevant surface speed here is the surface speed measured along the extension of the propeller axis, i.e., the propeller apparent speed in the water. Data indicating surface speed may also be related to the surface speed in front of the propeller (commonly referred to as...). This is related to the speed at which the ship moves through the water. This speed is typically lower than STW because the hull moves through the water and carries a certain amount of water. The two are at least approximately related. ,in This is the wake coefficient of the ship. Different ship hulls have different wake coefficients.

[0056] A ship's STW (Straight Towards Wing) is typically a combination of longitudinal, lateral, and yaw motions, but it can usually be well approximated by the ship's longitudinal velocity in the water, i.e. Based on available sensor data, the control system can be configured to determine the water velocity using a single speedometer or a set of different sensors. The control system 600 is configured to base its determination on the propeller speed of the drive unit 110. And the ship's speed relative to water at 100. To determine the propeller slip of the ship's drive unit Propeller slip indicates how fast the propeller rotates relative to the speed of the water flowing over it; the faster the propeller rotates relative to the speed of the water flowing over it, the greater the slip. If the boat is almost stationary, a relatively low propeller speed may produce a large slip, while a boat moving quickly in the water requires a considerably higher propeller speed to produce the same slip. If the drive unit is powered by an electric motor, very large propeller slip is often observed during boat startup because the torque applied by the motor is almost instantaneous in response to the control commands of the steering gear and does not accumulate over a short period of time like a combustion engine. The control system 600 is arranged to control the propeller speed of the boat drive unit 110. To slide the propeller Maintaining within the predetermined propeller slip limit This ensures that the propeller operates in the desired region 410 or the peak thrust region 420, rather than in the combined region. Figure 4 The undesirable operation in region 430 is discussed in the text.

[0057] In some cases, such as Figure 4In the first example 440, the propeller thrust is saturated due to propeller slip. This means that at some point, further increasing the propeller speed will not produce any significant additional thrust. A control system configured to obtain data indicating the desired thrust to be generated by the drive unit 110 and to determine the target propeller slip corresponding to the desired thrust based on the relationship between the drive unit thrust and propeller slip can operate near the saturation point (such as at...). or even in The propeller slip limit is configured at the location. Then, the control system will increase the propeller speed in response to the desired increase in thrust until the propeller slip limit is reached. At this point, further increases in the desired thrust will not cause an increase in propeller speed unless the water speed decreases.

[0058] Figure 5 Figure 500 illustrates an exemplary ship startup operation, where the propeller shaft speed is... and ship speed Changes over time. For this simplified illustrative example, it is assumed that the acceleration is constant. Solid line 510 shows the ship's velocity relative to the water. And the dashed line 520 indicates the propeller speed. In time At this point, the ship begins to accelerate from a standstill in the water. Therefore, the propeller speed increases to match the propeller slip. Corresponding points This results in near-optimal thrust, where the propeller slips somewhere within or near region 420. Maximum propeller speed. As indicated by the dashed line 530, it's important to note that the propeller will not immediately accelerate to this maximum speed, as this means the propeller-hull combination will eventually enter the aforementioned state. Figure 4 The discussion focuses on the undesirable high slip zone 430. Instead, as the ship accelerates in the water, the propeller speed gradually increases, always ensuring that the speed difference between the propeller speed and the ship's relative speed to the water, i.e., propeller slip, is maintained. Maintaining proximity and Figure 4 The peak region 420 corresponds to the propeller slip.

[0059] Meanwhile, the techniques discussed herein are used to efficiently achieve a desired propeller thrust level by controlling the propeller slip to a value corresponding to the desired propeller thrust level, provided that the resulting propeller slip is below the configured propeller slip limit. Specifically, this document discloses a control system 600 for controlling a propeller-based ship drive unit 110 on a vessel 100. This control system can be used separately from a control system configured to limit the propeller speed to a speed below the propeller slip limit, and the two can also be used in combination to leverage their advantages. The control system 600 is configured to obtain an indication of the vessel 100's speed relative to the water. The data, and is also configured to obtain the thrust of the drive unit. and propeller slip The relationship between the two is 400. The control system 600 is also configured to: acquire data indicating the desired thrust to be generated by the drive unit 110; and based on the drive unit thrust... and propeller slip The relationship 400 determines the target propeller slip corresponding to the desired thrust. The control system 600 is then able to control the propeller speed of the ship's drive unit 110. This is to generate a target propeller slip that provides the desired thrust.

[0060] In some cases, such as Figure 4 In the first example 440, the propeller thrust is saturated due to propeller slip. This means that at some point, further increasing the propeller speed will not produce any significant additional thrust. A control system configured to obtain data indicating the desired thrust to be generated by the drive unit 110 and to determine the target propeller slip corresponding to the desired thrust based on the relationship between the drive unit thrust and propeller slip can operate near the saturation point (such as at...). or even in The propeller slip limit is configured at the location. Then, the control system will increase the propeller speed in response to the desired increase in thrust until the propeller slip limit is reached. At this point, further increases in the desired thrust will not cause an increase in propeller speed unless the water speed decreases.

[0061] Drive unit thrust and propeller slip The relationships 400 can be configured as predetermined analytic functions or a predetermined set of analytic functions. These functions can be determined based on computer simulations or through practical experiments, or a combination of both. Mathematical analysis can also be used to derive these relationships. These relationships do not need to be highly precise; approximate relationships (such as linear approximations) have been found to produce good results in many cases. (Drive unit thrust) and propeller slip The relationship 400 can also be implemented as a pre-configured lookup table (LUT), which allows the conversion from thrust to propeller slip and vice versa to be achieved by indexing into the LUT.

[0062] Figure 6 Some exemplary components of a control system 600 for controlling a propeller-based ship drive unit 110 on a ship 100 are shown. The ship operator provides control commands 615 to the system 600 from the ship's steering device 610. These control commands may include a desired acceleration α to which the ship's motion is to follow. req and the desired curvature c req Ship operators are typically people who use steering input devices and throttle controllers, but can also operate the ship's computerized controllers through autopilot mode. So-called driver assistance systems are also known as systems that combine human operator input with computer control to control the vessel.

[0063] Control command 615 is received by the Vessel Motion Management (VMM) function 620, which translates high-level commands into low-level actuator controls 625 sent to one or more Motion Support Device (MSD) control units 630. The MSD control units then control physical actuators on the vessel 100, such as the propulsion unit 640, transmission unit 650, and steering unit 660, by issuing appropriate control commands 645, 655, and 665. Water velocity is obtained via one or more STW sensors 670. These sensors typically (but not necessarily) include a speedometer mounted on the vessel 100, and may also include a satellite positioning system receiver and sonar system arranged to measure ground speed, which indicates STW (Speed-to-Wave), although these are approximate values. Therefore, both the MSD control unit 630 and the VMM function 620 can obtain information indicating the vessel's speed relative to the water. The system components are also capable of determining the propeller rotation speed. Because the transmission settings of system 600 are known. Furthermore, the output shaft speed of propulsion device 640 is also known. If the propulsion unit 640 includes an electric motor, the motor shaft speed can essentially be determined from the motor drive circuitry. The teachings herein are particularly suitable for use with motors that can be controlled to precisely transmit the target shaft speed. If the propulsion unit is another type of engine, such as a combustion engine, the shaft speed can be determined by a shaft speed sensor, etc.

[0064] Same reference Figure 7 The VMM function 620 will receive the acceleration curve a from the steering device 610. req and curvature curve c reqThe commands 631 and 632 are continuously converted into control commands to control ship motion functions actuated by different MSDs (i.e., different propulsion and steering resources on the ship 100). Other systems on the ship 100 (such as ballast tanks, anti-roll fins, gyroscopes, etc.) can also be controlled by the VMM function.

[0065] The VMM function 720 performs ship state or motion estimation 720, meaning the VMM function 620 continuously determines the current ship state s(t) at time t by monitoring operations using various sensors 710 arranged on the ship 100 (such as the speedometer, satellite positioning system receiver, and inertial measurement unit (IMU) mentioned above), including, for example, position, speed, acceleration, and yaw motion. The VMM function 620 may also optionally perform motion prediction 730, i.e., estimate the future vehicle state s(t+T) at one or more future times t+T. Motion estimation 720 and motion prediction 730 are well-known techniques, and several exemplary implementations exist in the literature. Therefore, these sub-functions will not be discussed in more detail herein.

[0066] The results of motion estimation 720 and optional motion prediction 730 (i.e., the estimated vehicle state s(t) and possibly the predicted future vehicle state s(t+T)) are input to force generation module 740, which determines the force to cause vehicle 100 to accelerate according to the requested acceleration curve a. req and curvature curve c req The total force required for movement. This actuation can include both propulsion and steering, i.e., the actuation of the propulsion system and the rudder.

[0067] In this example, the required global force vector is input to the MSD coordination module 750, which distributes the force and coordinates the actuators. The coordinated actuators then work together to provide the desired lateral force Fy and longitudinal force Fx on the vessel, as well as the required torque Mz, to achieve the desired motion of the vessel 100. The MSD coordination module 750 optimizes the MSD distribution, with the primary objective being to satisfy the required global force. The MSD coordination module 750 outputs one or more target propeller slip values. and one or more rudder angles For example, suppose the ship is requested to accelerate from the steering gear; this would require increasing propeller slip to generate increased propeller thrust. However, the increase in propeller slip will not be so large as to lead to inefficiency; that is, the propeller slip will not exceed the propeller slip limits imposed by the system. If curvature is required, some steering can be applied, and if the ship has two or more drive units, the differences in propeller slip may be combined.

[0068] One or more interfaces 631, 632 transmit from VMM function 620 to different MSD controllers on board, such as motor controller, combustion engine controller and rudder controller.

[0069] VMM module 620 may be configured to request propeller slip from one or more MSD control modules 630. And / or request propeller speed from MSD control module 630 .

[0070] Figure 8A An exemplary vessel performing a turn maneuver 800 is shown. The vessel has two drive units, one on the starboard side and one on the port side. Additionally, there are two speedometers, STW-L and STW-R, configured to measure the velocity of each drive unit relative to the water. Utilizing the propeller slip-based control method discussed herein, it is noteworthy that the port propeller will rotate at a slightly lower speed than the starboard propeller, as the starboard propeller travels faster in the water due to its curvature. Both propellers maintain the same slip value. The operation, specifically, is a propeller skidding maneuver with the desired target in mind. This is in... Figure 8B The diagram shows propeller speeds, with the upper solid curve 860 representing the propeller speed of the starboard drive unit and the lower dashed curve 870 representing the propeller speed of the port drive unit. Since both propellers operate at the same speed, the thrust on both drive units is approximately the same. However, if a thrust differential is required (e.g., for steering assistance), the VMM function can, of course, select to allocate more or less propeller speed, i.e., a propeller slip differential.

[0071] Check Figure 8A As can be understood from the example, when a vessel has more than one drive unit, using a separate speedometer may be advantageous. According to some aspects, the control system is arranged to control multiple vessel drive units 110 on vessel 100. Control systems 600 and 1100 are configured to obtain indicated water speeds for at least two of the multiple drive units respectively. The data.

[0072] According to some aspects, in a dual-drive unit system performing a turning maneuver, the control system is arranged to interact with the propeller slip limit of the inner drive unit 810. Compared to configuring the external drive unit 820, it has a lower propeller slip limit. Here, "inner" and "outer" refer to the radial position of the propeller when the ship performs a turning maneuver, as indicated in Figure 8. The outer propeller travels faster than the inner propeller, at least in terms of ground clearance, because it travels a greater distance. The difference between the two slip limits can, for example, be configured as a function of the curvature of the turning maneuver, or a function of the ship's roll angle during the turning maneuver. Thus, an outer drive unit that may operate at a reduced draft will not experience the same amount of cavitation due to the reduced draft, which can also be considered when configuring the propeller slip for a given turning maneuver.

[0073] Taking into account the current depth of the propellers in a multi-propeller drive system, the VMM module 620 can dynamically configure the propeller slip limits of the multi-propeller system, for example, based on the estimated operating depth of the propellers in the multi-propeller system. During turning maneuvers, the inner propeller is positioned deeper in the water than the outer propeller, and therefore can typically support a larger propeller slip. The mapping between propeller slip limits and ship motion states (such as yaw rate, roll angle, etc.) can be predetermined, for example, as a LUT, etc.

[0074] Figure 9 This is an efficiency graph 900 for an exemplary motor. The motor speed is plotted on the x-axis, and the torque applied by the motor is plotted on the y-axis. The contour plot shows the motor efficiency, i.e., how much input power is converted into motion and how much is lost as heat, etc. The shape of this graph is similar for most motors. This exemplary motor is capable of providing high torque at low shaft speeds, and the maximum achievable applied torque subsequently decreases as the shaft speed increases. It is worth noting that there is an optimal applied torque for each propeller speed. Therefore, for a given speed 910, an applied torque 920 that maximizes the motor's operating efficiency can be found. Conversely, for a given applied (positive) torque, there exists a shaft speed that maximizes efficiency. According to some aspects, a control system 600 is arranged to control a ship drive unit 110 having an adjustable propeller pitch P. The control system 600 is arranged to control the propeller speed of the ship drive unit 110 based on a predetermined relationship 900 between efficiency, shaft speed, and the torque applied by the motor. And propeller pitch P, to generate target propeller slip. According to the example, propeller slip is first determined based on motion requests received from the ship's steering gear. Utilizing relevant transmission mechanisms and ship... The information allows the target propeller slip to be converted into an equivalent motor shaft speed. Given this motor shaft speed, an efficiency graph can be consulted, and the optimal pitch can be found through a direct linear search. The motor then generates the target propeller slip with the highest possible efficiency, according to the steering mechanism's request.

[0075] The VMM module 620 can coordinate the propellers of a multi-propeller system based on the efficiency map to achieve higher overall efficiency.

[0076] Figure 10 An exemplary control input device 1000 according to this teaching is shown. Typically, such as in... Figure 10 The thrust control input device, schematically illustrated, maps operator input commands to drive shaft torque, which is then converted into propeller shaft speed, independent of (or at least not intentionally controlled) the ship's water velocity. Alternatively, the control input device 1000 maps its position to a target propeller slip value via the relationship between drive unit thrust and propeller slip discussed above, and controls accordingly. In this way, operator commands are mapped to propeller slip, rather than to torque as in most conventional ship propeller thrust control devices. It is preferable to limit the target propeller slip such that the all-forward thrust command or all-reverse thrust command is limited to the configured positive or negative propeller slip limits. .

[0077] One positive side effect of the control input device 1000 is that the operation of the ship's drive unit becomes more energy-efficient, especially if the propeller slip limit is configured such that greater slip produces only a small amount of additional thrust. In more conventional control input devices, operators requiring more thrust can allow torque to be increased to a certain extent, where the additional torque only results in additional propeller slip without producing significant additional thrust. In fact, the additional torque added by the operator can even lead to a reduction in the obtained propeller thrust in some cases, as discussed above. Figure 4 As discussed.

[0078] Figure 11This is a schematic diagram of a computing system 1100 for implementing the examples disclosed herein. The computer system 1100 is adapted to execute instructions from a computer-readable medium to perform these and / or any functions or processes described herein. The computer system 1100 may be connected (e.g., networked) to other machines in a LAN, intranet, extranet, or the Internet. Although only a single device is shown, the computer system 1100 may include any collection of devices that individually or jointly execute a set of instructions (or more sets of instructions) to perform any one or more methods discussed herein. Therefore, any reference in this disclosure and / or the claims to computer systems, computing systems, computer devices, computing apparatuses, control systems, control units, electronic control units (ECUs), processor devices, processing circuitry, etc., includes references to one or more such devices to individually or jointly execute a set of instructions (or more sets of instructions) to perform any one or more methods discussed herein. For example, a control system may include a single control unit or multiple control units connected to or otherwise communicatively coupled to each other, such that any functions performed can be distributed among the control units as needed. Furthermore, such devices can communicate with each other or with other devices through various system architectures, such as directly or via a controller area network (CAN) bus.

[0079] Computer system 1100 may include at least one computing device or electronic device capable of including firmware, hardware, and / or executing software instructions to implement the functionality described herein. Computer system 1100 may include processing circuitry system 1102 (e.g., a processing circuitry system including one or more processor devices or control units), memory 1104, and system bus 1106. Computer system 1100 may include at least one computing device having processing circuitry system 1102. System bus 1106 provides interfaces for system components (including, but not limited to, memory 1104 and processing circuitry system 1102). Processing circuitry system 1102 may include any number of hardware components for performing data or signal processing or for executing computer code stored in memory 1104. Processing circuitry system 1102 may, for example, include a general-purpose processor, a special-purpose processor, a digital signal processor (DSP), an application-specific integrated circuit (ASIC), a field-programmable gate array (FPGA), circuitry containing processing components, a set of distributed processing components, a set of distributed computers configured to perform processing, or other programmable logic devices, discrete gate or transistor logic, discrete hardware components, or any combination thereof designed to perform the functions described herein. The processing circuit system 1102 may also include computer-executable code that controls the operation of the programmable device.

[0080] System bus 1106 can be any of several types of bus architectures, which can further interconnect to a memory bus (with or without a memory controller), a peripheral bus, and / or a local bus using any of a variety of bus architectures. Memory 1104 can be one or more means for storing data and / or computer code to perform or facilitate the methods described herein. Memory 1104 may include database components, object code components, script components, or other types of information structures for supporting the various activities described herein. Any distributed or local memory device may be used in conjunction with the systems and methods described herein. Memory 1104 may be communicatively connected to processing circuitry system 1102 (e.g., via circuitry or any other wired, wireless, or network connection) and may include computer code for performing one or more processes described herein. Memory 1104 may include non-volatile memory 1108 (e.g., read-only memory (ROM), erasable programmable read-only memory (EPROM), electrically erasable programmable read-only memory (EEPROM), etc.) and volatile memory 1110 (e.g., random access memory (RAM)) or any other medium that can be used to carry or store desired program code in the form of machine-executable instructions or data structures and can be accessed by a computer or other machine having processing circuitry system 1102. Basic Input / Output System (BIOS) 1112 may be stored in non-volatile memory 1108 and may include basic routines that facilitate the transfer of information between elements within computer system 1100.

[0081] Computer system 1100 may also include or be coupled to a non-transitory computer-readable storage medium, such as storage device 1114, which may include, for example, internal or external hard disk drives (HDDs) (e.g., Enhanced Integrated Drive Electronics (EIDE) or Serial Advanced Technology Accessories (SATA)), HDDs for storage (e.g., EIDE or SATA), flash memory, etc. Storage device 1114 and other drives associated with computer-readable and computer-usable media can provide non-volatile storage of data, data structures, computer-executable instructions, etc.

[0082] Computer code, whether hard-coded or soft-coded, may be provided as one or more modules. Modules may be implemented as software and / or hard-coded in circuitry to implement all or part of the functionality described herein. These modules may be stored in storage device 1114 and / or volatile memory 1110, which may include operating system 1116 and / or one or more program modules 1118. All or part of the examples disclosed herein may be implemented as a computer program 1120 stored on a transient or non-transitory computer-usable or computer-readable storage medium (e.g., a single medium or multiple media) such as storage device 1114, the computer program including complex programming instructions (e.g., complex computer-readable program code) that cause processing circuitry system 1102 to perform the actions described herein. Therefore, the computer-readable program code of computer program 1120 may include software instructions that, when executed by processing circuitry system 1102, implement the functionality of the examples described herein. In some examples, storage device 1114 may be a computer program product (e.g., a readable storage medium) on which computer program 1120 is stored, wherein at least a portion of computer program 1120 may be loadable (e.g., loaded into a processor) for implementing the functionality of the examples described herein when executed by processing circuitry system 1102. Processing circuitry system 1102 may act as a controller or control system for computer system 1100 that implements the functionality described herein.

[0083] Computer system 1100 may include an input device interface 1122 configured to receive input and selections to be transmitted to computer system 1100 when executing instructions such as those from a keyboard, mouse, touch-sensitive surface, etc. Such input devices may be connected to processing circuitry system 1102 via input device interface 1122 coupled to system bus 1106, but may also be connected via other interfaces such as parallel ports, IEEE 1394 serial ports, Universal Serial Bus (USB) ports, IR interfaces, etc. Computer system 1100 may include an output device interface 1124 configured to forward output to a display, video display unit (e.g., liquid crystal display (LCD) or cathode ray tube (CRT)). Computer system 1100 may include a communication interface 1126 suitable for communicating with a network, as needed or as required.

[0084] The actions described in any of the exemplary aspects of this document are provided for example and discussion. These actions may be performed by hardware components, may be embodied in machine-executable instructions to cause a processor to perform these actions, or may be performed by a combination of hardware and software. Although a particular order of method actions may be shown or described, the order of actions may differ. Furthermore, two or more actions may be performed simultaneously or partially simultaneously.

[0085] Figure 12 A computer-readable medium 1210 is shown carrying a computer program, the computer program comprising functions for executing when the program product is run on a computer. Figure 13 The method shown and the program code device 1220 of the techniques discussed herein. The computer-readable medium and the code device together form a computer program product 1200.

[0086] Figure 13 This is a flowchart illustrating at least some of the exemplary methods summarized in the above discussion. A computer-implemented method for controlling a ship drive unit 110 on a vessel 100 is shown, the method comprising: The computer system's processing circuitry obtains the relative speed of ship 100 to the water via S1. Data, The processing circuit system is based on the propeller speed of the drive unit 110. And the ship's speed relative to water at 100 To determine the propeller slip of the S2 ship drive unit ,as well as The propeller speed of the S3 ship drive unit 110 is controlled by the processing circuit system. To slide the propeller Maintaining within the predetermined propeller slip limit the following.

[0087] The operational steps described in any of the exemplary aspects of this document are described to provide examples and discussion. These steps may be performed by hardware components, embodied in machine-executable instructions to cause a processor to perform the steps, or performed by a combination of hardware and software. Although a particular order of method steps may be shown or described, the order of the steps may differ. Furthermore, two or more steps may be performed concurrently or partially concurrently.

[0088] The terminology used herein is for descriptive purposes only and is not intended to limit this disclosure. As used herein, unless the context clearly indicates otherwise, the singular forms “a,” “an,” and “described” are intended to also include the plural forms. As used herein, the term “and / or” includes any and all combinations of one or more of the associated listed items. It should also be understood that, when used herein, the term “comprising” indicates the presence of the described feature, integer, step, operation, element, and / or component, but does not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups thereof.

[0089] It should be understood that although the terms first, second, etc., may be used herein to describe various elements, these elements should not be limited by these terms. These terms are used only to distinguish one element from another. For example, without departing from the scope of this disclosure, a first element may be referred to as a second element, and similarly, a second element may be referred to as a first element.

[0090] In this document, relative terms such as “below,” “above,” “upper,” “lower,” “horizontal,” or “vertical” may be used to describe the relationship between one element and another, as illustrated in the figures. It should be understood that these terms, along with those discussed above, are intended to cover different device orientations in addition to those depicted in the figures. It should be understood that when an element is referred to as “connected” or “coupled” to another element, the element may be directly connected or coupled to the other element, or there may be intermediate elements present. In contrast, when an element is referred to as “directly connected” or “directly coupled” to another element, there are no intermediate elements present.

[0091] Unless otherwise defined, all terms used herein (including technical and scientific terms) shall have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure pertains. It should also be understood that, unless expressly defined herein, terms used herein shall be interpreted as having the same meaning as they have in the context of this specification and the relevant field, and not in an idealized or overly formal sense.

[0092] It should be understood that this disclosure is not limited to the aspects described above and shown in the accompanying drawings; rather, those skilled in the art will recognize that many changes and modifications can be made within the scope of this disclosure and the appended claims. Aspects have been disclosed in the drawings and description for illustrative purposes only and not for limiting purposes, and the scope of the inventive concept is set forth in the appended claims.

Claims

1. A control system (140, 600, 1100) for controlling at least one ship drive unit (110) on a ship (100), The control system (140, 600, 1100) is configured to obtain the water velocity STW(v) of the vessel (100). W , v A (data) The control system (140, 600, 1100) is configured to operate based on the propeller speed (ω) of the drive unit (110). p ) and the water velocity (v) of the vessel (100). W To determine the propeller slip (λ) of the at least one ship drive unit (110), The control system (140, 600, 1100) is configured to obtain the thrust (F) of the drive unit. x The relationship between () and propeller slip (λ) (400), and The control system (140, 600, 1100) is configured to obtain data indicating the desired thrust to be generated by the drive unit (110), and based on the drive unit thrust (F) x The relationship between (400) and propeller slip (λ) is used to determine the target propeller slip corresponding to the desired thrust. The control system (140, 600, 1100) is arranged to control the propeller speed (ω) of the ship drive unit (110). p To generate the target propeller slip, and to maintain the propeller slip (λ) at a predetermined propeller slip limit (λ). lim )the following.

2. The control system (140, 600, 1100) according to claim 1, wherein the ship drive unit (110) includes a motor arranged to provide a target shaft speed upon request from the control system (140, 600, 1100).

3. The control system (140, 600, 1100) according to claim 1 or 2, which is arranged to receive an indication of water speed (v) from a speedometer arranged on the vessel (100). W The data mentioned above.

4. The control system (140, 600, 1100) according to any one of the preceding claims, which is arranged to receive, in the form of ground velocity data from a global positioning system and / or from a sonar sensor system arranged on the vessel (100), an indication of water velocity (v). W The data mentioned above.

5. The control system (140, 600, 1100) according to any one of the preceding claims, which is arranged to obtain the drive unit thrust (F) at least in part in the form of a predetermined analytical function or a predetermined set of analytical functions. x The relationship between propeller slip (λ) and propeller slip (λ) (400).

6. The control system (140, 600, 1100) according to any one of the preceding claims, wherein the drive unit thrust (F) x The relationship (400) between the propeller slip (λ) and the propeller slip (λ) includes a pre-configured lookup table (LUT).

7. The control system (140, 600, 1100) according to any one of the preceding claims, wherein the control system is arranged to control a plurality of ship drive units (110) on the vessel (100), wherein the control system (140, 600, 1100) is configured to obtain indicated water speeds (v) for at least two of the plurality of drive units respectively. W The data mentioned above.

8. A control system (140, 600, 1100) according to any one of the preceding claims, arranged to control a port drive unit (810) and a starboard drive unit (820), wherein the control system is arranged to control the propeller slip limits of the inner drive unit (810) for turning maneuvers in the port drive unit and the starboard drive unit. In contrast, the outer drive unit (820) for the turning maneuver in the port and starboard drive units is configured with a lower propeller slip limit. .

9. A control system (140, 600, 1100) according to any one of the preceding claims, arranged to control a ship drive unit (110), the ship drive unit having an adjustable propeller pitch (P) and including a motor controlled by the control system, wherein the control system (140, 600, 1100) is arranged to control the propeller speed (ω) of the ship drive unit (110) based on a predetermined relationship (900) between efficiency, motor shaft speed, and applied torque of the motor. p The propeller pitch (P) and the propeller pitch (P) are used to generate the target propeller slip (λ).

10. The control system (140, 600, 1100) according to any one of the preceding claims, comprising a centralized ship motion management VMM module (620) arranged to request propeller slip (λ) from at least one motion support device MSD control module (630).

11. The control system (140, 600, 1100) according to any one of the preceding claims, comprising a centralized ship motion management (VMM) module (620), the VMM module being arranged to request propeller speed (ω) from at least one motion support device (MSD) control module (630). p ).

12. A vessel (100) comprising a control system (140, 600, 1100) according to any one of claims 1 to 11.

13. A computer-implemented method for controlling a ship drive unit (110) on a ship (100), the method comprising: The computer system's processing circuitry obtains (S1) the indicative water velocity (v) of the vessel (100). W (data) The processing circuit system uses the propeller rotation speed (ω) of the drive unit (110) as a basis. p ) and the water velocity (v) of the vessel (100) W To determine the propeller slip (λ) of the ship drive unit described in (S2), Obtain the thrust (F) of the drive unit x The relationship between propeller slip (λ) and propeller slip (λ) (400), Obtain data indicating the desired thrust to be generated by the drive unit (110). Based on the thrust (F) of the drive unit x The relationship between (400) and propeller slip (λ) is used to determine the target propeller slip corresponding to the desired thrust, and The propeller speed (ω) of the ship drive unit (110) is controlled (S3) by the processing circuit system. p To generate the target propeller slip, and to maintain the propeller slip (λ) at a predetermined propeller slip limit (λ). lim )the following.

14. A computer program product (1100) comprising program code (1120) for performing the method of claim 13 when executed by a processing circuit system.

15. A non-transitory computer-readable storage medium (1110) comprising instructions (1120) that, when executed by a processing circuit system, cause the processing circuit system to perform the method according to claim 13.

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