Marine propulsion control system and method

Abstract

To provide a system and a method for providing horizontal direction and rotary propulsion by a mechanically steered device or another non-steer-by-wire type steering device.SOLUTION: A marine propulsion system includes: propulsion devices which are at least two parallel propulsion devices generating advancing and backing propulsion respectively, the parallel propulsion devices being oriented so that the propulsion thereof are in parallel to each other; and at least one drive position sensor composed to sense driving angles of the parallel propulsion devices. A horizontal direction thruster is composed to generate starboard and port side thrust for propelling a vessel. A user input device is capable of being operated by a user to provide at least a horizontal thrust command for performing horizontal direction movement of the vessel and a rotational thrust command for performing rotational movement of the vessel.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates generally to methods and systems for propelling marine vessels, and more particularly to systems and methods for providing lateral and rotational propulsion with mechanically steered or other non-steer-by-wire steering devices. [Background technology]

[0002] The following US patents are incorporated herein by reference in their entirety:

[0003] Many different types of marine propulsion devices are known to those skilled in the art, such as outboard motors mounted on the transom of a vessel, stern drive systems extending aft from the transom of a vessel, bow thrusters and other docking thrusters. In addition to bow thrusters, certain types of docking thruster systems used with vessels incorporate multiple propulsors that respond to joystick or other control inputs by the vessel operator.

[0004] U.S. Patent No. 6,234,853 discloses a docking system that utilizes a vessel's marine propulsion devices under the control of an engine control device that receives command signals from a joystick or push-button device to respond to operational commands from a vessel operator. This docking system does not require any additional propulsion devices beyond those normally used to maneuver the vessel under normal conditions. The docking or maneuvering system of this invention uses two marine propulsion devices to respond to the operator's command signals and allows the operator to select forward or reverse commands combined with clockwise or counterclockwise rotation commands, either in combination with each other or independently.

[0005] U.S. Patent No. 6,402,577 discloses a hydraulic steering system in which the steering actuator is an integral part of the support structure of the marine propulsion system. The steering arm is entirely contained within the support structure of the marine propulsion system and is disposed about its steering axis. The steering arm extension extends into a slip joint having linear and rotational components that allow the steering arm extension to move relative to a movable second portion of the steering actuator. The movable second portion of the steering actuator moves linearly within a cylindrical cavity formed in a first portion of the steering actuator.

[0006] U.S. Patent No. 6,406,340 discloses a hydraulic steering assembly that applies force to the tiller arms of twin marine outboard propulsion units and rotates the units about a steering axis between a center position and full positions on either side of the center position. Each propulsion unit is supported for arcuate movement about a tilt axis generally perpendicular to the steering axis. There is a hydraulic steering unit attached to the first propulsion unit, with a hydraulic cylinder pivotally connected to a member pivotally mounted to the tiller arm of the first propulsion unit. A tie bar is pivotally connected to the steering unit and to the tiller arm of the second propulsion unit. For example, the tie bar may be pivotally connected to the steering unit by a ball-and-socket joint that is connected to the steering unit by a bracket that moves with the member.

[0007] No. 7,398,742 discloses a steering assist system that provides differential thrust by two or more marine propulsion devices to generate an effective turning moment for the vessel. The differential thrust can be selected as a function of the magnitude of the turn commanded by the vessel operator and also as a function of the vessel's speed when the turn command is received.

[0008] No. 7,467,595 discloses a method for controlling the movement of a vessel that rotates one of a pair of marine propulsion devices and controls the magnitude of thrust of the two marine propulsion devices. A joystick is provided to enable the vessel operator to select port-starboard, forward-reverse and rotation direction commands that are interpreted by a control device and then cause the angular position of at least one of the pair of marine propulsion devices relative to its steering axis.

[0009] U.S. Patent No. 9,039,468 discloses a system for controlling the speed of a vessel, including first and second propulsion devices that generate first and second thrusts for propelling the vessel. A control circuit controls the orientation of the propulsion devices between an aligned position in which the thrusts are parallel and an unaligned position in which the thrusts are not parallel. A first user input device is movable between a neutral position and a non-neutral detent position. When the first user input device is in the detent position and the propulsion devices are in the aligned position, the thrust propels the vessel in a desired direction at a first speed. When a second user input device is actuated while the first user input device is in the detent position, the propulsion devices move to the unaligned position and propel the vessel in a desired direction at a second, reduced speed without changing the thrust.

[0010] U.S. Patent No. 10,259,555 discloses a method for controlling the movement of a vessel near an object, including receiving a signal from a joystick representing a desired movement of the vessel. A sensor senses the shortest distance between the object and the vessel and the direction of the object relative to the vessel. A controller compares the desired movement of the vessel with the shortest distance and direction. Based on the comparison, the controller selects whether to command the marine propulsion system to generate thrust to achieve the desired movement, or alternatively, to command the marine propulsion system to generate thrust to achieve a corrected movement that ensures the vessel maintains at least a predetermined distance from the object. The marine propulsion system then generates thrust to achieve the desired or corrected movement as commanded.

[0011] U.S. Patent No. 8,512,085 discloses a tie bar arrangement for a marine vessel having at least first and second marine drive units, the tie bar arrangement including a linkage geometrically configured to connect the first and second marine drive units to one another such that the first and second marine drive units are steered at different angles about respective first and second vertical steering axes during turning movements of the vessel. Summary of the Invention

[0012] This Summary is provided to introduce selected concepts that are further described below in the Detailed Description. This Summary is not intended to identify key or essential features of the claimed subject matter, nor is it intended to be used as an aid in limiting the scope of the claimed subject matter.

[0013] In one embodiment, a marine propulsion system includes at least two parallel propulsion units, each generating a forward and a reverse thrust, the parallel propulsion units oriented so that their thrusts are parallel to one another, and at least one drive position sensor configured to sense a drive angle of the parallel propulsion units. The lateral thrusters are configured to generate starboard and port thrusts for propelling the marine vessel. The user input device is operable by a user to provide at least a lateral thrust command for commanding a lateral movement of the marine vessel and a rotational thrust command for commanding a rotational movement of the marine vessel. The controller is configured to control the parallel propulsion units and the lateral thrusters based on the lateral steering input and / or the rotational steering input and the drive angle to provide the lateral and / or rotational movement commanded by the user without controlling the drive angle.

[0014] One embodiment of a method for controlling propulsion of a marine vessel includes receiving at least one of a lateral steering input for commanding lateral movement of the marine vessel and a rotational steering input for commanding rotational movement of the marine vessel, then sensing at least one of a drive angle of a set of parallel propulsion drives on the marine vessel and a yaw rate of the marine vessel, and then using the drive angle and / or yaw rate to determine a thrust magnitude and a forward or astern direction of thrust for each propulsion unit in the set of parallel propulsion units, and to determine an actuation command and a starboard or port direction of thrust for a lateral thruster to achieve the lateral and / or rotational movement commanded by a user without controlling the drive angle of the set of parallel propulsion units.

[0015] Various other features, objects and advantages of the present invention will become apparent from the following description taken in conjunction with the drawings.

[0016] The present disclosure will be described with reference to the following figures. [Brief explanation of the drawings]

[0017] [Figure 1] 1 is a schematic diagram of a watercraft equipped with an embodiment of a propulsion system according to the present disclosure. [Figure 2] 2A-2E are schematic diagrams of various movements of a vessel. [Figure 3] 1 illustrates an exemplary joystick user input device. [Figure 4] 1 illustrates an exemplary keypad user input device. [Figure 5A] 1 shows various thrust vectors for the vessel to achieve various vessel movements; [Figure 5B] 1 shows various thrust vectors for the vessel to achieve various vessel movements; [Figure 5C] 1 shows various thrust vectors for the vessel to achieve various vessel movements; [Figure 5D] 1 shows various thrust vectors for the vessel to achieve various vessel movements; [Figure 5E] 1 shows various thrust vectors for the vessel to achieve various vessel movements; [Figure 5F] 1 shows various thrust vectors for the vessel to achieve various vessel movements; [Figure 6] 1 illustrates a method for controlling the propulsion of a marine vessel according to an embodiment of the present disclosure. [Figure 7] 1 illustrates a method for controlling the propulsion of a marine vessel according to an embodiment of the present disclosure. [Figure 8] 1 illustrates a method for controlling the propulsion of a marine vessel according to an embodiment of the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0018] The present inventors have recognized a need for a vessel control system that provides lateral and rotational user control, such as that provided by a standard joystick system, for non-steer-by-wire vessels in which the steering wheel is mechanically connected to a propulsion device mounted on the stern of the vessel via a conventional steering system. In vessels configured for high-speed applications, such as racing vessels, the mechanically steered propulsion devices are typically tethered together by tie bars or the like. This provides robust steering actuation and control under high load conditions and high vessel speeds. As another example, lower-cost vessels typically implement conventional mechanical steering systems, in which the propulsion devices are mechanically connected to the steering wheel and steered together, often connected by tie bars. In both of these applications, as well as other non-steer-by-wire steering and propulsion systems, the propulsion devices are maintained parallel so that the thrust forces achieved are parallel to one another. These existing systems do not provide lateral thrust control or automatic rotational thrust control that allows a user to command rotational movement without any forward or reverse movement. Joysticks or other lateral thrust control elements are not currently available for non-steer-by-wire systems. Currently available joystick systems require steer-by-wire control that allows each propulsion unit to be steered separately and that allows the propulsion units to be positioned at angles that are not parallel to one another.

[0019] Based on the above-mentioned problems and challenges in the related art, the present inventors have developed the presently disclosed propulsion system and method that enables lateral and rotational steering control, such as via a joystick, for mechanically steered marine vessels and other non-steer-by-wire marine vessels. The presently disclosed system and method enable user lateral and rotational steering control without controlling or adjusting the angle of the propulsion devices relative to the marine vessel, and thus can be implemented on marine vessels with traditional mechanical steering of the propulsion devices. In one embodiment, the presently disclosed system includes a set of two or more parallel propulsion devices, each generating forward and reverse thrust, and a sensor system configured to determine the drive angles of the parallel propulsion devices. In some embodiments, the system may further include lateral thrusters configured to generate lateral thrust in each of the starboard and port directions. A user input device, such as a joystick or keypad, is manually operable by a user to provide at least lateral and rotational steering inputs to command a corresponding movement of the marine vessel, and a controller configured to control the magnitude and direction of thrust by the parallel propulsion devices and / or the lateral thrusters to achieve the commanded movement without requiring any steering control over the propulsion devices.

[0020] FIG. 1 is a schematic diagram of a vessel 2 equipped with a propulsion system 100 having two propulsion units 21 and 22 mounted on a transom 24 and arranged in parallel. The number of propulsion units is exemplary, and one skilled in the art, in light of this disclosure, will understand that any number of two or more propulsion units can be utilized in the systems and methods of the present disclosure. In the illustrated example, the propulsion units 21 and 22 are connected and maintained in parallel by tie bars 23. Tie bars are conventional in many marine applications, such as high-speed racing vessels, where tie bars are often used between engines to help distribute steering loads during high-speed operation. Tie bars may be attached to the parallel propulsion units 21 and 22 at their respective steering axes 31 and 32. The steering axes 31 and 32 are separated by a dimension Y and a distance X from a center of turn (COT) 30, which may also be the effective center of gravity (COG). The vessel 10 is steered by rotating the first and second propulsion units about their respective steering axes 31 and 32. The parallel propulsion units 21 and 22 are rotated in response to operator manipulation of a steering wheel 12 that is mechanically connected to a steering actuator 14 that conventionally rotates the propulsion units 21 and 22. Mechanical connection systems 13 for transmitting rotational movement of the steering wheel 12 to the steering actuator 14, such as steering linkage systems and / or push-pull cable systems, are well known and may include a hydraulically actuated steering system with a hydraulic steering actuator 14, thereby rotating the parallel propulsion units 21 and 22 and providing thrust, thereby causing rotation of the vessel 10 about the effective COT 30.

[0021] The propulsion system 100 further includes a user input device 40, such as a joystick or keypad, operable by a user to provide at least lateral steering inputs to command lateral movement of the vessel 10 and rotational steering inputs to command rotational movement of the vessel 10. FIGS. 2A-2E illustrate exemplary vessel movements that can be commanded via the user input device 40. In FIG. 2A, the vessel 10 is shown moving laterally in a port direction 46 and a starboard direction 48 without any forward or reverse movement and without any rotation about its COT 30. FIG. 2B illustrates the vessel 10 moving in a forward 50 and a reverse 52 direction. FIG. 2C illustrates a combination of forward and starboard movement of the vessel 10, where the forward movement is represented by dashed arrow 56 and the starboard movement is represented by dashed arrow 58. The resulting movement vector 60 moves the vessel in a forward and starboard direction without any rotation. Figure 2D shows a clockwise rotation 62 of the vessel 10 about the COT 30 without any translational movement, including any forward / reverse or lateral movement. Figure 2E shows a combination of rotation 62 and translation 60 in both the forward and starboard directions.

[0022] The disclosed systems and methods enable lateral and rotational movement of a vessel such as that shown in Figures 2A-2E without requiring steering control of the propulsion units 21 and 22, which are mechanically steered by the steering wheel 12. Thus, the disclosed systems and methods control the magnitude of thrust and forward or reverse direction for each parallel propulsion unit without adjusting or otherwise controlling the drive angle of the set of parallel propulsion units.

[0023] User steering inputs provided at user input devices 40 are received at a controller 34, which is communicatively connected to engine control modules (ECMs) 41 and 42 of each propulsion unit 21 and 22, respectively. The controller 34 can then communicate commands to each ECM 41 and 42 to achieve the commanded magnitude of thrust and the commanded direction of thrust (forward or astern), as needed, to implement the lateral and / or rotational steering inputs commanded at the user input devices 40. In certain embodiments, the system 100 includes lateral thrusters 15 configured to provide lateral thrust in the starboard and port directions relative to the vessel 10. In the illustrated example, the lateral thrusters 15 are bow thrusters located in the bow region 11 of the vessel 10 and configured to provide lateral thrust at the bow. Bow thrusters are well known to those skilled in the art, as are other types and locations of docking thruster systems configured to provide lateral thrust relative to the vessel 10, which may be located at other locations on the vessel 10 other than the bow 11. Those skilled in the art will understand in light of the present disclosure that the propulsion system 100 of the present disclosure may include other types and locations of lateral thrusters 15, which may be in place of or in addition to the bow thruster.

[0024] The lateral thrusters 15 include fans 16 or propellers rotated in a forward or reverse direction by bidirectional motors 17 to provide lateral thrust in the starboard and port directions. The controller 34 may be communicatively connected to a controller 18 for the lateral thrusters 15 to control the operation and direction of thrust by the lateral thrusters 15. Thus, in one embodiment, rotation is either on or off, rotating at a single speed in clockwise and counterclockwise directions. In other embodiments, the lateral thrusters 15 are variable-speed thrusters, in which the motors 17 are controllable to rotate the fans 16 at two or more speeds. For example, the motors 17 may be brushless DC motors configured for variable multi-speed control of the fans 16 in both clockwise and counterclockwise rotational directions.

[0025] The disclosed systems and methods take advantage of the parallelism of the propulsion units 21 and 22. By providing forward thrust from one propulsion unit and reverse thrust from the other with parallel and equal thrust vectors, the translational forces combine to cancel each other. The combined forces impart a torque about the COT 30. Knowing the drive angles of the propulsion units, vector analysis can be performed to achieve any rotational movement, lateral movement to port 46 and starboard 48 (in an embodiment incorporating lateral thrusters 15), and forward 50 and reverse 52 movement. In certain embodiments, the system 100 may be configured to provide translational movement in other translational directions, combining forward / reverse and port / starboard thrust.

[0026] FIGS. 3 and 4 illustrate two possible types of user input device 40. FIG. 3 shows a known joystick device having a base 68 and a movable handle 66 suitable for movement by an operator. Typically, the handle can be moved left and right, forward and backward, and rotated relative to the base 68 to provide corresponding movement commands for the propulsion system. The operation of joystick thrust controls is well known to those skilled in the art and is described in the references incorporated herein by reference. FIG. 4 shows another user input device 40b that is a keypad having buttons 64 associated with each of the right, left, forward, reverse, and rotational movement directions. Thus, a user can press forward button 64a to provide a forward thrust command to move the vessel forward, and a user can press key 64b to input a sideways thrust command to command a sideways movement of the vessel 10. Similarly, a user can press clockwise rotation key 64c to input a clockwise rotation thrust command to command a clockwise rotational movement of the vessel 10. The other keys on the keypad 40b operate similarly.

[0027] The propulsion system 100 of the present disclosure allows for control by a joystick or another user input device operable to provide lateral and rotational thrust control over the mechanically coupled and steered drive units. Therefore, steer-by-wire is not required; the controller 34 is configured to calculate thrust magnitude and direction using the current position of the marine drive units. The system 100 is configured to utilize the parallelism of the propulsion units 21 and 22 so that thrust from the two or more propulsion units can cancel each other to achieve the desired resulting rotational and translational thrust. In one embodiment with a lateral thruster 15, the propulsion system 100 can achieve lateral movement in lateral movement directions 46 and 48, as well as forward and reverse movement directions 50 and 52, as shown in FIGS. 2A and 2B.

[0028] 5A-5F illustrate this force coupling control between the propulsion units 21 and 22 and the lateral thrusters 15 to achieve rotational and translational movement of the vessel without changing or controlling the drive angles of the propulsion units 21 and 22. The controller 34 is configured to measure the drive angle θ of the parallel propulsion units 21 and 22 or otherwise determine the rotational effect of the thrust from the propulsion units 21 and 22. In one embodiment, the drive position sensor 44 (FIG. 1) is configured to sense the drive angle of at least one of the parallel propulsion units 21 and 22. If the propulsion units 21 and 22 are maintained parallel, such as by tie bars 23, it is necessary to sense the drive angle of only one propulsion unit 21, 22. However, in other embodiments, a position sensor may be provided for each propulsion unit 21 and 22, for example, to provide redundancy in the event of a failure. The drive angle sensed by the position sensor provides information about the drive angle or steering position of the propulsion unit, which is manually controlled by the operator via the steering wheel 12 and is not controlled by the controller 34. Based on the drive angle, the controller 34 can adjust the magnitude and direction of thrust from the parallel thrusters 21 and 22 and / or the lateral thrusters 15. If the drive angle θ changes, the controller 34 adjusts the magnitude and direction of thrust to accommodate the new steering position sensed by the drive position sensor 44.

[0029] In another embodiment, the controller 34 may be configured to utilize yaw rate, such as from an inertial measurement unit 26 or other rotational sensor capable of measuring the yaw of the vessel 10, as a basis for controlling thrust magnitude and direction. A yaw rate sensor, such as an inertial measurement unit (IMU), may be included in place of the drive position sensor 44. In such an embodiment, the controller 34 receives the yaw position and / or yaw rate from the IMU 26, determines thrust magnitude, and determines the forward or reverse direction of thrust for each propulsion unit 21 and 22 based on the yaw rate command. In one embodiment, the controller 34 estimates the drive angle θ of the parallel propulsion units based on the sensed yaw rate and calculates the thrust magnitude and direction accordingly. For example, the controller 34 may receive engine speed and / or throttle position from the ECMs 41 and 42 and may estimate the drive angle based on values ​​related to yaw rate and thrust magnitude, such as RPM or throttle position.

[0030] The sensed yaw rate can further be used as a feedback control to adjust the thrust commands. That is, the controller 34 may determine an expected yaw rate associated with the lateral and / or rotational thrust commands from the user input device 40 and may compare the measured yaw rate from the IMU 26 with the expected yaw rate and adjust the thrust commands to reduce the difference between the measured and expected yaw rates. Such feedback control can be utilized in embodiments with or without the drive position sensor 44. In such embodiments, the propulsion system 100 includes both the drive position sensor 44 and the IMU 26 or other yaw rate sensor.

[0031] 5A-5F illustrate exemplary thrust scenarios for achieving rotational and translational movement when the drive units are at drive angle θ. In FIG. 5A, propulsion units 21 and 22 provide opposing thrusts of equal magnitude to achieve clockwise rotational movement of vessel 10. To achieve the desired rotational and / or translational movement commanded via user input device 40, force vectors from the propulsion units on the port and starboard sides of centerline 33 at the stern of the vessel, as well as the thrust vector from bow thruster 15, if utilized, are added using normal vector analysis. That is, thrust vector F1 for first propulsion unit 21, i.e., the total thrust of the propulsion units on the port side of centerline 33, is in the forward thrust direction to achieve forward movement of the vessel. Thrust vector F2 for starboard propulsion unit 22, i.e., all propulsion units on the starboard side of centerline 33 of vessel 10, is in the astern thrust direction to achieve astern movement of vessel 10. The magnitudes of the forward thrust vector F1 and the reverse thrust vector F2 are equal so that only the translational force cancellation and resulting moment to turn the vessel in a clockwise rotational direction is achieved. Here, the bow thruster 15 is not operating and remains in an off state.

[0032] 5B shows force vectors F1-F3 that are implemented to cause a lateral movement of the vessel 10 in the starboard direction. Here, the lateral thruster 15 is actuated at the bow of the vessel to achieve a starboard thrust vector F3. The thrust from the bow thruster 15 generates a clockwise moment about the pivot point 30 in addition to a lateral force in the starboard direction. To move the vessel 10 in the starboard direction, the moment created by the bow thruster 15 is countered by realizing an equal and opposite moment from the propulsion units 21 and 22, so that the resulting moment equals zero and only the lateral force F3 remains.

[0033] 5C shows the force vectors for achieving forward movement of the vessel 10 when the propulsion units 21 and 22 are at an angle θ. Here, the bow thruster 15 provides a thrust force F3 in the port direction, which generates a counterclockwise moment about the COT 30. The counterclockwise moment is countered by thrust forces F1 and F2 of the propulsion units at the stern of the vessel 10, where the port side propulsion unit provides a forward thrust force F1, and the starboard side propulsion unit provides a thrust force F2 in the astern direction, which generates a clockwise moment. However, the magnitude of the forward thrust vector F1 is greater than the astern thrust vector, and the resulting total thrust is applied thereto to move the vessel 10 forward.

[0034] 5D shows the opposite scenario of realizing a total thrust force against the vessel 10 to move it in the astern direction. The bow thruster 15 is commanded to provide a thrust force F3 in the port direction, which generates a moment about the pivot point 30 that is countered by the thrust forces F1 and F2 of the propulsion units at the stern of the vessel 10. Here, the magnitude of the thrust vector F2 in the astern direction is greater than the thrust vector F1 in the forward direction, and therefore a total thrust force is realized to move the vessel in the astern direction.

[0035] As will be recognized by those skilled in the art in light of this disclosure, other combinations of thrust may be implemented to achieve the total thrust commanded by the user. Figures 5E and 5F illustrate further exemplary thrust combinations for achieving forward and reverse thrust, respectively. In Figure 5E, both propulsion devices are controlled to achieve equal forward thrusts F1 and F2, and the bow thruster 15 is commanded to provide a thrust F3 in the starboard direction, which generates a moment about the center of turn 30 that counteracts the moment generated by the thrusts F1 and F2. In Figure 5F, both propulsion devices are controlled to achieve equal reverse thrusts F1 and F2, and the bow thruster 15 is commanded to provide a thrust F3 in the port direction, which generates a moment about the center of turn 30 that counteracts the moment generated by the thrusts F1 and F2.

[0036] 6-8 illustrate a method 200, or portions thereof, for controlling the propulsion of a marine vessel according to an embodiment of the present disclosure. In FIG. 6, step 202 receives a lateral or rotational thrust command at a user input device, such as a joystick. Step 204 senses the drive angle of the parallel propulsion units and / or the yaw rate of the vessel, and steps 206 and 208 use that information to determine the thrust command. In embodiments where the drive position sensor 44 is not provided and only IMU data or yaw rate information from another type of motion sensor is available, the system may be configured to estimate the drive angle based on the yaw rate, as described above. For example, the drive angle θ may be estimated based on engine speed and / or throttle position and yaw rate by each ECM 41 and 42. Step 206 determines an actuation command and a starboard or port direction command for the lateral thruster, and step 208 determines a thrust magnitude and a forward or reverse direction command for each of the parallel propulsion units. The lateral thrusters and propulsion units are then actuated in step 210 to achieve the commanded movement.

[0037] 7 illustrates a process for using a sensed yaw rate as feedback to control thrust. In step 220, an expected yaw rate is determined based on lateral and / or rotational commands. For example, a lookup table or formula may be used to correlate joystick or keypad inputs with yaw rate. In step 222, the measured yaw rate, such as by an IMU, is then compared to the expected yaw rate. In step 224, if the difference between the measured and expected yaw rates exceeds a threshold, the magnitude and / or direction of thrust from the propulsion system and / or lateral thrusters is redetermined to minimize the difference between the measured and expected yaw rates.

[0038] FIG. 8 illustrates method 200 steps for controlling parallel propulsion units in a lateral thruster using drive position information. A lateral or rotation command is received at 230 via a user input device. A drive angle θ is sensed at 232 by a drive position sensor 44 configured to sense the angular position of at least one of the parallel propulsion units at the transom of the vessel. Then, at step 234, a thrust magnitude and direction are determined for each of the parallel propulsion units and the thruster based on the drive angles measured as described above. Then, at step 236, the thrust is implemented. If a change in drive angle is detected, as represented at step 238, the thrust magnitude and direction are redetermined for the propulsion unit and the lateral thruster based on the changed drive angle at step 240. Then, at step 242, a new thrust is implemented. Thus, if the drive angle θ or steering position of the parallel propulsion units 21 and 22 changes due to a user applying a steering input at the steering wheel 12, a thrust vector calculation is re-performed to implement the appropriate thrust to maintain the commanded movement of the vessel.

[0039] This specification uses examples, including best mode examples, to disclose the invention and also to enable any person skilled in the art to make and use the invention. Specific terminology has been used for brevity, clarity, and understanding. Such terminology is used merely for convenience and is intended to be broadly interpreted, without imposing unnecessary limitations thereon beyond the requirements of the prior art. The patentable scope of the invention is defined by the claims and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they have features or structural elements that do not differ from the literal words of the claims, or if they contain equivalent features or structural elements that have insubstantial differences from the literal words of the claims.

Claims

1. at least two parallel propulsion units, each generating forward and reverse thrust, steerable by rotation about a steering axis and mechanically connected to one another, said parallel propulsion units being steerable together to maintain their thrust directions parallel to one another; at least one drive position sensor configured to sense a drive angle of at least one of the parallel propulsion devices; lateral thrusters configured to generate starboard and port thrust for propelling the vessel; a user input device operable by a user to provide at least lateral thrust commands for commanding lateral movement of the vessel and rotational thrust commands for commanding rotational movement of the vessel; a control device configured to control the parallel propulsion units and the lateral thrusters based on the lateral thrust command and / or the rotational thrust command and the drive angle to provide the lateral movement and / or the rotational movement commanded by the user without controlling the drive angle of the parallel propulsion units; and A marine propulsion system comprising:

2. determining a thrust magnitude and a forward or reverse thrust direction for each parallel propulsion device based on the drive angle; determining an actuation command and a starboard or port direction of thrust for the lateral thrusters; Controlling the parallel propulsion devices based on the thrust magnitude and the forward or reverse direction of the thrust, and controlling the lateral thrusters based on the thrust actuation command and the starboard or port direction. The system of claim 1 further configured to:

3. The system of claim 1 , wherein the user input device is one of a joystick or a keypad.

4. The system of claim 1 , wherein the at least two parallel propulsion units are connected to each other by tie bars.

5. The system of claim 1 , further comprising a steering wheel mechanically coupled to a steering actuator configured to rotate the parallel propulsion devices about a steering axis to control the drive angle.

6. 3. The system of claim 2, wherein the control device is configured to redetermine the thrust magnitude and the forward or reverse direction of the thrust for each of the parallel propulsion devices according to changes in the drive angle.

7. 10. The system of claim 1, wherein the lateral thruster is a variable speed thruster, and the lateral thrust command for the lateral thruster controls a rotational speed of the variable speed thruster.

8. 10. The system of claim 1, further comprising a yaw rate sensor configured to measure a yaw rate of the vessel, and wherein the parallel propulsion devices and the lateral thrusters are further controlled based on the yaw rate of the vessel.

9. at least two parallel propulsion units, each generating forward and reverse thrust, steerable by rotation about a steering axis and mechanically connected to one another, the parallel propulsion units being oriented so that their thrust forces are parallel to one another; at least one yaw rate sensor configured to measure the yaw rate of the vessel; lateral thrusters configured to generate starboard and port thrust for propelling the vessel; a user input device manually operable by a user to provide at least lateral thrust commands for commanding lateral movement of the vessel and rotational thrust commands for commanding rotational movement of the vessel; Estimating a drive angle of the parallel propulsion units based on the measured yaw rate; and controlling the parallel propulsion devices and the lateral thrusters based on the lateral thrust command and / or the rotational thrust command and the estimated drive angle to provide the lateral movement and / or the rotational movement commanded by the user without controlling the drive angle of the parallel propulsion devices; A control device configured as follows: A marine propulsion system comprising:

10. The control device determining that the measured yaw rate differs from an expected yaw rate associated with the lateral thrust command and / or the rotational thrust command by at least a threshold amount; re-estimating the drive angles of the parallel propulsion units based on a difference between the measured yaw rate and the expected yaw rate; The system of claim 9 further configured to:

11. The system of claim 9 , wherein the user input device is a joystick.

12. The system of claim 9 , wherein the at least two parallel propulsion units are connected to each other by tie bars.

13. receiving at least one of a lateral thrust command for commanding a lateral movement of the vessel and a rotational thrust command for commanding a rotational movement of the vessel from a user input device; sensing at least one of a drive angle of a set of parallel propulsion devices on the vessel that are steerable by rotation about a steering axis and mechanically connected to one another, and a yaw rate of the vessel; determining a thrust magnitude and a forward or aft direction of thrust for each propulsion unit in the set of parallel propulsion units and a thrust actuation command and a starboard or port direction for a lateral thruster based on the lateral thrust command and / or the rotational thrust command and the drive angle and / or the yaw rate; controlling each of the propulsion units and the lateral thrusters to provide the lateral and / or rotational movement commanded at the user input device without controlling the drive angle of the parallel propulsion units; 1. A method for controlling the propulsion of a vessel, comprising:

14. The method of claim 13 , wherein the drive angle is sensed by at least one drive position sensor associated with one of the parallel propulsion units in the set of parallel propulsion units.

15. 14. The method of claim 13, further comprising detecting a change in the drive angle of the parallel propulsion units, and then redetermining at least the thrust magnitude and the forward or reverse direction of the thrust for each propulsion unit in the set of parallel propulsion units based on the changed drive angle and the lateral thrust command and / or the rotational thrust command.

16. 16. The method of claim 15, wherein the drive angle is sensed by a drive position sensor, and a change in the drive angle is detected based on an output from the drive position sensor over time.

17. determining that the sensed yaw rate differs from an expected yaw rate associated with the lateral thrust command and / or the rotational thrust command by at least a threshold amount; redetermining at least the thrust magnitude and the forward or reverse direction of the thrust for each of the propulsion units in the set of parallel propulsion units based on a difference between the sensed yaw rate and the expected yaw rate; 14. The method of claim 13, further comprising:

18. 18. The method of claim 17, further comprising estimating a drive angle of the parallel propulsion units based on the sensed yaw rate, and then calculating the thrust magnitude and the forward or reverse direction of the thrust for each of the propulsion units based on the estimated drive angle.

19. 14. The method of claim 13, wherein the lateral thruster is a single velocity thruster, and the actuation command for the lateral thruster is one of an on command or an off command.

20. 14. The method of claim 13, wherein the lateral thruster is a variable speed thruster, and the actuation command for the lateral thruster controls a rotational rate of the variable speed thruster.

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