JOYSTICK SYSTEMS AND METHODS FOR MARINE PROPULSION SYSTEMS

Description

FIELD

The present disclosure generally relates to methods and systems for propelling marine vessels, and more particularly to systems and methods for controlling steering and propulsion for propulsion systems comprising at least one steerable marine drive.

BACKGROUND

Many different types of marine drives are well known to those skilled in the art. For example, steerable marine drives may be mounted to or in the rear of the vessel, such as outboard motors that are attached to the transom of a marine vessel and stern drive systems that extend in a rearward direction from the stern of a marine vessel. Marine drives generally comprise a powerhead, such as an electric motor or an internal combustion engine, driving rotation of a drive shaft that is directly or indirectly connected to a propeller on a propeller shaft and that imparts rotation thereto. Some marine propulsion systems include groups of two or more and separately steerable marine drives at the rear of the marine vessel to enable surge, sway, and yaw directional control. The steerable marine drives are each steerable about their steering axis to a range of steering angles, which is effectuated by a remotely controlled steering actuator, often referred to as a steer-by-wire system. User input control of such multi-drive propulsion systems is often provided by a joystick, which is configured to move forward, backward, and sideways to any position on a horizontal plane to command a thrust direction, as well as to twist to command a yaw rotation of the vessel.

The following U.S. patent is incorporated herein by reference, in its entirety:

U.S. Pat. No. 7,467,595 discloses a method for controlling the movement of a marine vessel that rotates one of a pair of marine drives and controls the thrust magnitudes of two marine drives. A joystick is provided to allow the operator of the marine vessel to select port-starboard, forward-reverse, and rotational direction commands that are interpreted by a controller which then changes the angular position of at least one of a pair of marine drives relative to its steering axis.

SUMMARY

This Summary is provided to introduce a selection of 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.

In one aspect, a marine propulsion system for a marine vessel includes at least one rear marine drive configured to be positioned near a stern of the marine vessel, a joystick comprising a joystick handle configured to be movable by a user to provide steering demand input, and a control system. The control system is configured to receive a selection input selecting one of two steering response modes for the joystick, wherein each steering response mode yields a different steering direction in response to certain rotation inputs at the joystick handle. The control system determines a steering direction to steer the at least one rear marine drive based on the rotation input and the selected steering response mode and controls a steering actuator to steer the rear marine drive in the steering direction.

In one embodiment, the rotation input is a rotation of a handle of the joystick in a clockwise or counterclockwise rotational direction about a shaft axis of the handle.

In another embodiment, each of the two steering response modes yields a different steering direction in response to the rotation of the joystick handle when it is provided with a reverse thrust command, such as with a backward deflection of the joystick handle.

In another embodiment, each of the two steering response modes yields a different response to a rotation-only input via the joystick.

In another embodiment, the two steering response modes include a first mode wherein the rear marine drive is steered counterclockwise in response to a clockwise rotation input via the joystick and steered clockwise in response to a counterclockwise rotation of the joystick handle, and a second mode wherein the rear marine drive is steered to rotate the vessel clockwise in response to a clockwise rotation of the joystick handle and steered to rotate the vessel counterclockwise in response to a counterclockwise rotation of the joystick handle.

In another embodiment, in the second mode, the marine drive is steered counterclockwise in response to a forward deflection with clockwise rotation of the joystick handle and steered clockwise in response to the forward deflection with counterclockwise rotation of the joystick handle, and the marine drive is steered clockwise in response to a backward deflection with clockwise rotation of the joystick handle and steered counterclockwise in response to the backward deflection with counterclockwise rotation of the joystick handle.

In another embodiment, the selection input is a user input via a user input device on the vessel.

In another embodiment, the user input device is a display on the vessel.

In another embodiment, the user input device is a button on the joystick.

In another embodiment, the selection input is provided as part of installing the propulsion system on the marine vessel.

In another embodiment, the control system is further configured to control the marine drive to not generate any thrust output in response to a rotation-only input, wherein the rotation-only input is a rotation of a handle of the joystick in a clockwise or a counterclockwise rotational direction about a shaft axis of the handle while the joystick handle remains in a centered position.

In another embodiment, the control system is further configured to control a gear system of the marine drive to be in a centered position in response to the rotation-only input.

In another embodiment, in the second mode, the steering direction determination in response to a rotation-only input is based further on at least one of a translation direction of the marine vessel, a direction of a last-generated propulsion output, a current or past gear position of the marine drive, and a current or past rotation direction of a propulsor.

In another aspect, a method of controlling a propulsion system on a marine vessel, wherein the propulsion system includes at least one a rear marine drive positioned near a stern of the marine vessel includes receiving a selection input selecting one of two steering response modes for the joystick, wherein each of the two steering response modes yields a different steering direction in response to certain rotation inputs at the joystick, receiving a rotation input via a joystick, determining a steering direction to steer the at least one rear marine drive based on the rotation input and the selected steering response mode, and controlling a steering actuator to steer the rear marine drive in the steering direction.

In one embodiment, the rotation input is a rotation of a handle of the joystick in a clockwise or counterclockwise rotational direction about a shaft axis of the handle.

In another embodiment, each of the two steering response modes yields a different steering direction in response to the rotation of the joystick handle when it is provided with a reverse thrust command.

In another embodiment, each of the two steering response modes yields a different response to a rotation-only input via the joystick.

In another embodiment, in the second mode, the steering direction determination in response to a rotation-only input is based further on at least one of a translation direction of the marine vessel, a direction of a last-generated propulsion output, a current or past gear position of the marine drive, and a current or past rotation direction of a propulsor.

In another embodiment, the two steering response modes include a first mode and a second mode, wherein in response to the selection input selecting the first mode the rear marine drive is steered counterclockwise in response to a clockwise rotation of the joystick handle and steered clockwise in response to a counterclockwise rotation of the joystick handle, and in response to the selection input selecting the second mode the rear marine drive is steered to rotate the vessel clockwise in response to a clockwise rotation of the joystick handle and steered to rotate the vessel counterclockwise in response to a counterclockwise rotation of the joystick handle.

In another embodiment, in response to the selection input selecting the second mode, the marine drive is steered counterclockwise in response to a forward deflection with clockwise rotation of the joystick handle and steered clockwise in response to the forward deflection with counterclockwise rotation of the joystick handle, and the marine drive is steered clockwise in response to a backward deflection with clockwise rotation of the joystick handle and steered counterclockwise in response to the backward deflection with counterclockwise rotation of the joystick handle.

In another embodiment, the method further comprises controlling the marine drive to not generate any thrust output in response to a rotation-only input, wherein the rotation-only input is a rotation of the handle of the joystick in a clockwise or a counterclockwise rotational direction about a shaft axis of the handle while the joystick handle remains in a centered position.

In another embodiment, the method further comprises controlling a gear system of the marine drive to be in a centered position in response to the rotation-only input.

In another embodiment, the selection input is a user input via a user input device on the vessel.

In another embodiment, the selection input is provided as part of installing the propulsion system on the marine vessel.

Various other features, objects, and advantages of the invention will be made apparent from the following description taken together with the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The present disclosure is described with reference to the following Figures.

FIG. 1 is a schematic illustration of a marine vessel with one embodiment of a marine propulsion system according to the present disclosure.

FIG. 2 is a schematic illustration of motion control achievable by a propulsion system with a single rear drive according to one embodiment of the present disclosure.

FIGS. 3A-3B are schematic illustrations of various movements of a marine vessel.

FIG. 4 illustrates an exemplary joystick user input device.

FIGS. 5A-5D are exemplary steering directions determined in response to the rotation input and a first selected steering response mode, according to one embodiment of the present disclosure.

FIGS. 6A-6D are exemplary steering directions determined in response to the rotation input and a second selected steering response mode, according to another embodiment of the present disclosure.

FIG. 7 is a flowchart illustrating exemplary logic for determining the steering direction of a marine vessel, according to one embodiment of the present disclosure.

FIG. 8 is a flowchart illustrating exemplary method steps of controlling a propulsion system on a marine vessel, according to one embodiment of the present disclosure.

DETAILED DESCRIPTION

The inventors have recognized that different users have different preferences in terms of which direction drives should be steered in response to joystick inputs, particularly in response to joystick inputs commanding yaw movement with reverse thrust movement. Some users differ in their preferred frame of reference when effectuating thrust commands. Wherein some users intend the joystick rotation input to mimic the steering direction response corresponding the response to input at a steering wheel, others prefer the joystick steering response to move the marine vessel in the same direction as the rotation of the joystick. Accordingly, the inventors have recognized a need for a joystick control system and method that enables a user to choose how a rear marine drive is steered in response to a joystick command. Specifically, the inventors have recognized a need for a joystick system and method that enables selection from a plurality of joystick steering response modes to be applied when operating the joystick.

In view of the foregoing challenges, the inventors developed the disclosed joystick propulsion control system and method for a propulsion system that enables a selection input selecting one of at least two steering response modes for the joystick, wherein each steering response mode dictates a different steering direction in response to certain rotation inputs of the joystick. The steering modes include at least a first steering response mode where the steering direction response to joystick inputs mimics that of a manually connected steering wheel response, and a second steering mode where the marine drives are steered in the direction needed to rotate the marine vessel in the same direction as the rotation input at joystick handle. In an exemplary first mode, the steering wheel mode, the control system is configured to steer the rear marine drive counterclockwise in response to a clockwise rotation of the joystick handle and steer the rear marine drive clockwise in response to a counterclockwise rotation of the joystick handle. In an exemplary second mode, the control system is configured to steer the rear marine drive in a direction needed to rotate the marine vessel the same direction as the joystick handle is rotated—i.e., the at least one rear marine drive is steered to rotate the marine vessel clockwise in response to a clockwise rotation of the joystick handle and steered to rotate the marine vessel counterclockwise in response to a counterclockwise rotation of the joystick handle. Thus, in the second mode, the at least one rear marine drive may be steered in different rotational directions in response to a given rotational direction of the joystick handle, depending on whether the joystick rotation is accompanied by forward or backward tilt of the handle commanding forward surge movement or backward surge movement, respectively.

Accordingly, the disclosed marine propulsion control system and method are configured to determine a steering direction in response to a rotation input at the joystick and the selected steering response mode, and then the steering actuator is controlled to steer the marine drive in the steering direction. In one embodiment, where the yaw command at the joystick is a yaw-only command (i.e., not provided in conjunction with a forward or backward translation command) the steering direction determination may also be based on, for example, a translation direction of the marine vessel. The system may be configured to determine the translation direction of the vessel using course over ground and heading information (e.g., from a GPS, IMU, heading sensor, and/or other navigation sensor). In another embodiment, the translation direction may be intuited or estimated based on the direction of the last-generated propulsion output, a current or past gear position of the marine drive, or a current or past rotation direction of the propulsor.

FIG. 1 is a schematic representation of a marine vessel 10 equipped with a marine propulsion system 100 including one rear marine drive 21 positioned at the stern 24, such as attached to the transom. The single rear marine drive 21 may be mounted along a centerline CL of vessel 10, which is to be understood as generally laterally centered with respect to the beam of the vessel 10 such that when the steerable rear marine drive 21 is in a centered steering position it propels the marine vessel approximately or exactly straight ahead (under ideal conditions with no current, wind, or other lateral forces). Though applicable to a propulsion system comprising only a single rear marine drive 21, the disclosed methods and system may be implemented with propulsion systems comprising multiple rear marine drive configurations, as well as propulsion systems comprising marine drives at other locations on the vessel, such as lateral thrusters positioned at the bow or at other locations on the vessel.

The marine drive 21 may be, for example, an outboard drive, a stern drive, an inboard drive, a jet drive, or any other type of steerable drive. The rear marine drive 21 includes a powerhead driving a propulsor into rotation to generate a thrust to propel the marine vessel 10. The powerhead may be an electric motor, and internal combustion engine (ICE), or a hybrid including one or more electric motors and an ICE. The rear marine drive 21 is steerable, having a steering actuator 13 configured to rotate the drive 21 about its vertical steering axis 31. The rear marine drive 21 may be steerable about the steering axis 31 to a range of steering angles 32, such as wherein the range of steering angles 32 is no greater than between +30 and −30 degrees of a centered steering position, or between +45 degrees and −45 degrees of a centered steering position, or between some other range. The steering axis 31 is positioned at a distance X from the center of turn (COT) 30, which could also be the center of pressure (COP), or in other embodiments calculations may be based on the effective center of gravity. The marine vessel 10 is maneuvered by causing the rear marine drive to rotate about its steering axis 31. The rear marine drive 21 is rotated in response to an operator's manipulation of the steering wheel 12 or joystick 40, which is communicatively connected through the control system 33 to the steering actuator 13 to rotate the marine drive 21. Rotating the rear marine drive 21 and effectuating thrust thereby cause rotation of the marine vessel 10 about the effective COT 30.

The powerhead of the rear marine drive is operably connected to the propulsor 9 and configured to rotate the propulsor 9. As will be known to the ordinary skilled person in the relevant art, the propulsor 9 may include one or more propellers, impellers, or other propulsor devices and the term “propulsor” may be used to refer to all such devices. In certain embodiments, such as that represented in FIG. 1, the powerhead may be connected and configured to rotate the propulsor 9 through a gear system 7, such as a transmission or a clutch. In such an embodiment, the gear system 7 translates rotation of the powerhead output shaft 5 to the propulsor shaft 8 to adjust conversion of the rotation, direction of the rotation (e.g., often referred to as “forward” where the propulsor 9 is turned to propel the vessel forward and “reverse” where the propulsor 9 is turned to propel the vessel backward). The gear system 7 may also be configured to disconnect the propulsor shaft 8 from the drive shaft 5, as is sometimes referred to in the art as a “neutral” or “centered” position where rotation of the drive shaft 5 is not translated to the propulsor shaft 8. In other embodiments, the powerhead may directly connect to the propulsor shaft 8 such that rotation of the drive shaft 5 is directly transmitted to the propulsor shaft 8 at a constant and fixed ratio, such as where the powerhead is an electric motor. A propeller speed sensor 6 may be configured to measure a rotational speed of the propulsor 9. For example, the propeller speed sensor 6 may be, for example, a Hall Effect sensor or other rotation sensor, such as using capacitive or inductive measuring techniques. In certain embodiments, one or more of the parameters, such as the speed, torque, or power to the electric motor 4, may be calculated based on other measured parameters or characteristics. These parameters may be monitored by the control system to indicate a direction and/or speed of rotation of the propulsor.

The control system 33 may be configured to utilize yaw rate, such as from an inertial measurement unit (IMU) 26 or other rotational sensor capable of measuring yaw of the marine vessel 10, as the basis for controlling steering and thrust magnitude and direction from the rear marine drive 21. The IMU typically contains accelerometers, a gyroscope, and a magnetometer. Additionally, the GPS 35, a motion sensor (IMU 26), and/or a separate heading sensor (such as an accelerometer and/or a gyroscope), may be configured to measure and indicate the translation direction of the marine vessel. The sensed yaw rate can be used as feedback control for adjusting the steering and/or thrust commands. Namely, the control system 33 may determine an expected yaw rate, or yaw velocity, associated with a rotational thrust command from the joystick 40 and may compare the measured yaw rate from the IMU 26 to the expected value(s) and adjust the thrust and/or steering commands to reduce the difference between the measured and expected values, such as between the measured yaw rate and the expected yaw rate.

Referring now to FIGS. 2-4, the control system may be configured to control steering and/or thrust of the rear marine drive 21 based on steering demand input to generate a demanded forward 50 motion, the backward 52 motion, and/or rotational motion 55 of the marine vessel 10. The marine propulsion system may include a joystick 40 and a display 232, such as configured to be installed at the helm of the marine vessel 10, to control the steering and/or thrust of the rear marine drive on the marine vessel.

Referencing FIG. 4, the joystick 40 device comprises a base 68, a shaft 70, and a moveable joystick handle 66 suitable for movement by an operator to provide steering demand input. Typically, the handle 66 can be moved forward and back (represented by arrow 67a), as well as twisted (represented by arrow 67b) about its shaft axis 71 relative to the base 68 to provide corresponding movement commands for the propulsion system. The joystick 40 is configured such that the joystick handle 66 is movable in a forward 50 direction to demand a forward 50 motion of the marine vessel, in a backward 52 direction to demand backward 52 motion of the marine vessel, and twistable to demand rotational motion of the marine. When the joystick handle 66 is twisted to demand a rotational motion, the rotational movement effectuated in response may depend on the selected joystick steering response mode, as is described herein.

FIGS. 3A-3B illustrate exemplary vessel movements that may be commanded via the joystick 40. FIG. 3A shows the vessel 10 moving in the forward 50 direction and backward 52 direction, also known as surge movement. FIG. 3B illustrates a combination of yaw movement, represented by arrow 62, and surge and sway translation in the forward and starboard directions, represented by arrow 60. The system 100 is configured to provide translational movement in the forward and backward translational directions and to combine forward/reverse and yaw by adjusting the steering angle of the at least one rear marine drive 21, and may also be configured to control one or more lateral drives (e.g. thrusters) to effectuate the lateral motion.

The user steering inputs provided at the joystick 40 are received by the control system 33, which may include multiple control devices communicatively connected via a communication link, such as a CAN bus (e.g., a CAN Kingdom Network), to control the marine propulsion system 100 as described herein. In the embodiment of FIG. 1, the control system 33 includes a central controller 34 communicatively connected to the drive control module (DCM) 41 of the rear marine drive 21 and may include other control devices. Thereby, the controller 34 can communicate instructions to the DCM 41 of the rear drive 21 to effectuate a commanded magnitude of thrust and a commanded direction of thrust (forward or reverse), as is necessary to effectuate rotational steering inputs commanded at the joystick 40. The controller 34 also communicates a steering position command to the steering actuator 13 to steer the marine drive 21. Drive position sensor 44 is configured to sense the steering angle, or steering position, of the drive 21, such as to provide feedback for controlling steering of the rear marine drive 21. In some implementations, the central controller 34 may be a helm control module and the controller 41 may be a propulsion control module. A person of ordinary skill in the art will understand in view of the present disclosure that other control arrangements could be implemented and are within the scope of the present disclosure, and that the control functions described herein may be combined into a single controller or divided into any number of a plurality of distributed controllers that are communicatively connected. The control system 33 may include one or multiple hardware controllers, which in various embodiments and arrangements may be communicatively connected by a communication bus, such as a CAN bus, or configured for wireless communication.

In one embodiment, the control system is configured to receive a selection input selecting one of two steering response modes for the joystick, wherein each steering response mode yields different steering directions in response to certain rotation inputs of the joystick. In one embodiment, the selection input is a user input via a user input device on the vessel, such as the display, or selecting a button on the joystick. Thus, the user selects one of the two joystick steering response modes via the user input device. For example, the joystick 40 may include multiple selection buttons, including a dedicated button for engagement of each of the various joystick steering response modes. Alternatively, the display 232 may provide a user interface configured to present a user with selectable inputs associated with each of the joystick steering response modes. For example, the display 232 may be a multi-function display (MFD) as the helm of the vessel. One example of such a display is the Vessel View® by Mercury Marine Company of Fond du Lac, Wisconsin. Thus, the user may be able to select the “steering-type” response joystick mode via a button on the joystick or a selection on the display, where the steering response to joystick inputs mimics the steering response of a mechanically connected steering wheel steering system or a “joystick-type” response joystick mode button or display selection where the steering response to joystick inputs follows the rotational direction of the joystick. In another embodiment, the selection input is provided as part of installing the propulsion system on the marine vessel, such as a selection made by the installer at the time that the propulsion system (including the joystick system) is installed on the marine vessel. In one embodiment, the selection input made at the time of installation may be changeable, such as via accessing the joystick settings on the display. Additionally or alternatively, the control system 33 may be configured to receive a mode selection input from one or more mobile devices not positioned at the helm of the vessel, such as a user's mobile device communicating with the control system 33 via an application, such as via VesselView Mobile® by Mercury Marine.

Referring now to FIGS. 5A-5D, operation in the first joystick steering response mode is illustrated. In the first mode, the steering response to rotational movement of the joystick 40 handle mimics the steering direction response associated with the corresponding rotation input at a steering wheel. In the first mode, rotation of the joystick handle 66 in a specific direction (clockwise or counterclockwise) is associated with a fixed direction of rotation of the marine drive 21. Namely, a clockwise rotation of the joystick handle 66 is associated with a counterclockwise rotation steering command of the marine drive 21 and a counterclockwise rotation of the joystick handle 66 is associated with a clockwise rotation steering command of the marine drive 21.

Referring to FIG. 5A, in response to a forward deflection 222 and a clockwise rotational direction 220a of the handle 66 of the joystick 40, the control system determines a counterclockwise steering direction 216a of the marine drive 21 and rotates the rear marine drive about its steering axis 31 accordingly. Here, the forward deflection is associated with a forward thrust command, and the forward propulsion combined with the steering will rotate the marine vessel 10 in a clockwise 250 direction and forward.

Referring to FIG. 5B, in response to a forward deflection 222 and a counterclockwise rotational direction 220b of the joystick handle 66, the control system steers the marine drive 21 in a clockwise steering direction 216b about its steering axis 31. The forward deflection is associated with a forward thrust command and the forward propulsion will rotate the marine vessel 10 in a counterclockwise direction 252 and forward.

As depicted in FIG. 5C, in response to a backward deflection 224 and a clockwise rotational direction 220a of the joystick handle 66, a counterclockwise steering direction 216a of the marine drive 21 is effectuated. The backward deflection of the handle 66 is associated with a reverse thrust command, and the reverse propulsion combined with the steering of the marine drive will rotate the marine vessel 10 in a counterclockwise direction 252 (thus opposite the rotational direction of the joystick handle).

As depicted in FIG. 5D, in response to a backward deflection 224 and a counterclockwise rotational direction 220b of the joystick handle, a clockwise steering direction 216b of the marine drive 21 is effectuated along with a reverse thrust command, and the reverse propulsion combined with the steering will rotate the marine vessel 10 in a clockwise 250 direction (thus opposite the rotational direction of the joystick handle).

Referring now to FIGS. 6A-6D, operation in the second joystick steering response mode is illustrated. In the second mode, the steering response to the joystick rotation with forward deflection is the same as the steering response to the corresponding joystick inputs in the first mode. Thus, the steering direction responses illustrated in FIGS. 6A and 6B are the same as those illustrated in FIGS. 5A and 5B.

However, if the steering demand input includes a command for backward motion of the marine vessel 10, then the steering direction responses will be opposite those effectuated when operating in the first mode. Thus, the steering responses illustrated in FIGS. 6C and 6D are opposite those illustrated in FIGS. 5C and 5D. As illustrated in FIG. 6C, the clockwise rotation input 220a at the joystick handle 66 that is provided with a backward deflection 224 of the joystick handle 66 is associated with a clockwise rotation direction 216b of the marine drive 21 about its steering axis. As illustrated in FIG. 6D, a counterclockwise rotation input 220b at the joystick handle 66 accompanied by a backward deflection 224 of the joystick handle 66 is associated with a counterclockwise rotation direction 216a of the drive 21 about its steering axis 31. Thus, when a reverse thrust is commanded, the marine drive 21 is steered clockwise 216b in response to clockwise rotation input 220a at the joystick handle 66 and steered counterclockwise direction 216a in response to counterclockwise rotation input 220b at the joystick handle. Thus, rotation of the joystick handle 66 in the second mode reflects the direction of rotation of the marine vessel effectuated in response—i.e., the clockwise rotational direction 220a of the handle correlates with a clockwise rotational motion 250 of the marine vessel 10 and the counterclockwise rotational direction 220b of the handle correlates with a counterclockwise rotational motion 252 of the marine vessel.

As shown in FIGS. 6A-6D, the rotation direction of the steering response in the second steering response mode is dependent on wither the yaw command input is provided in conjunction with a forward thrust command or a reverse thrust command—i.e., whether the joystick handle rotation is accompanied by a forward deflection or a backward deflection of the handle. However, a rotation-only command is also possible, where the joystick handle is twisted about its axis 71 while the joystick handle remains in a neutral, centered position. In the second mode, the steering response to the rotation-only input may take on various embodiments. In one embodiment, the marine drive may not rotated at all in response to the rotation-only input—i.e., the control system will on generate any steering response at the rear marine drive 21 in response to the rotation-only input. In another embodiment, the rotation-only input may be associated with the forward thrust steering response (FIGS. 6A-6B) by default. In still another embodiment, the rotation-only input may be associated with the reverse thrust steering response (FIGS. 6C-6D) by default.

In still another alternative embodiment, the rear marine drive is steered based on a measured or estimated motion of the marine vessel. In such an embodiment, when the marine vessel is moving forward the at least one rear marine drive is steered in the directions shown in FIGS. 6A and 6B and when the marine vessel is moving backward the at least one marine drive is steered in the directions shown in FIGS. 6C and 6D. Accordingly, in such an embodiment, the control system includes logic for determining which direction to turn the drive 21, in response to a rotation-only command at the joystick 40. In some versions of this embodiment, the marine vessel is steered in response to the rotation-only input, but no thrust is effectuated. Thus, the steered drive acts as a rudder to rotate the marine vessel in the commanded direction.

FIG. 7 provides a detailed flowchart providing exemplary logic for determining the steering direction in the second mode based on measured or estimated vessel motion when a rotation-only steering demand input is received. At 300, the control system receives a steering demand input in the form of rotation-only input. After receiving the rotation-only input, at 302 the control system determines whether measured translation is detected. The measured translation may include a translation direction and a translation magnitude. The translation direction may be the direction that the marine vessel is moving, such as the direction that the vessel is moving in relation to the vessel heading. The measured translation may also include the predetermined recent period, wherein the measured translation may be within the predetermined recent period. The detection of measured translation may be determined based on output of at least one of a GPS 35, a motion sensor 26 (such as the IMU), and/or a heading sensor. Output from these devices may include a change in GPS location, a heading change, a change in acceleration, etc.

If there is not a measured translation, at 306, the control system may be configured to determine whether there is other information upon which the steering direction determination should be based, such as by accessing stored data regarding a last-commanded propulsion direction, last-commanded shift, or last-commanded propulsor rotation direction. Identification of the last-commanded propulsion may be combined with the received steering demand input to identify the steering direction of the rear marine drive (such as at steps 308 and 314). In one embodiment, the control system is configured to determine a direction of a last-commanded or last-generated propulsion output by the marine drive (e.g., forward or reverse), and determine the steering direction based on the direction of the last-generated propulsion output. The last-commanded or last-generated propulsion output may be generated within a predetermined recent period, and may be determined based on previous propulsion commands or sensed values, such as a rotational direction of the propulsor, the rotational direction of the powerhead of the marine drive (e.g., with an electric motor powerhead), a sensed gear position, etc. during the last-generated propulsion output. The sensed values may include current or previous sensed values.

If there is a measured translation, the control system may determine whether the marine vessel is moving or coasting in a forward direction or a reverse direction (step 304). Determination of the direction of the measured translation may be combined with the received steering demand input and the last commanded propulsion direction, shift command, or propulsor rotation direction, to determine the steering direction of the rear marine drive. Determination of a last commanded propulsion direction may include a shift command, if applicable, or a commanded propulsion sent from the helm.

At steps 308 and 314, the rotation direction of the joystick handle, combined with the measured or estimated movement direction of the vessel, dictates the steering response direction (steps 310, 312, 316, and 318). A measured or logically identified reverse translation results in steering the marine drive clockwise (towards the port side of the marine vessel) in response to a clockwise rotation-only input (step 310). A measured or logically identified reverse translation results in steering the marine drive counterclockwise (towards the starboard side of the marine vessel) in response to receiving a counterclockwise rotation-only input (step 312). A measured or logically identified forward translation results in steering the marine drive counterclockwise (towards the starboard side of the marine vessel) in response to receiving a clockwise rotation-only input (step 316). A measured or logically identified forward translation results in steering the marine drive clockwise (towards the port side of the marine vessel) in response to receiving a counterclockwise rotation-only input (step 318).

Switching between the first mode and/or the second mode, and the user selection thereof, may be facilitated by a button 234 (see FIG. 6A) on the joystick 40. In some embodiments, the joystick may include two buttons, selectable for either the first mode or the second mode. In another embodiment, selection of a steering response mode may be indicated by depressing a single button 234 a predetermined number of times or holding the button 234 for a predetermined period of time. Additionally or alternatively, the steering response mode in tandem with a selection on a helm display 232 on the marine vessel, such as within settings accessed through the display 232. For example, the display 232 may be a multi-function display (MFD) as the helm of the vessel.

Referring now to FIG. 8, exemplary method steps of controlling a propulsion system on a marine vessel are illustrated. At 805, a selection input selecting one of two steering response modes for joysticking is received by the control system. The two steering response modes include a first mode wherein the rear marine drive is steered counterclockwise in response to a clockwise rotation input via the joystick and steered clockwise in response to a counterclockwise rotation input via the joystick, and a second mode wherein the rear marine drive is steered to rotate the marine vessel clockwise in response to a clockwise rotation input via the joystick and steered to rotate the marine vessel counterclockwise in response to a counterclockwise rotation input via the joystick. The mode selection may be received as a user input via a user input device, such as a display on the marine vessel or a button on the joystick. Alternatively, the selection input may be provided as part of installing the propulsion system on the marine vessel. At 810, a yaw command is received as rotation input at the joystick handle. At 815, a steering direction to steer the at least one rear marine drive is determined by the control system based on the rotation input and the selected steering response mode. At 820, the control system controls a steering actuator to steer the rear marine drive in the steering direction.

This written description uses examples to disclose the invention, including the best mode, and also to enable any person skilled in the art to make and use the invention. Certain terms have been used for brevity, clarity, and understanding. No unnecessary limitations are to be inferred therefrom beyond the requirement of the prior art because such terms are used for descriptive purposes only and are intended to be broadly construed. 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 language of the claims, or if they include equivalent features or structural elements with insubstantial differences from the literal languages of the claims.