Patent Grant
9598163
The present disclosure relates to methods and systems for controlling steering actuators in a marine propulsion system. More specifically, the present disclosure relates to methods and systems for steering a marine vessel having one or more sets of at least two marine propulsion devices rotated by a single steering actuator.
The following U.S. patents and patent applications are hereby incorporated herein by reference.
U.S. Pat. No. 6,821,168 discloses an outboard motor provided with an internally contained cylinder and moveable piston. The piston is caused to move by changes in differential pressure between first and second cavities within the cylinder. The hydraulic steering system described in U.S. Pat. No. 6,402,577 is converted to a power hydraulic steering system by adding a hydraulic pump and a steering valve to a manual hydraulic steering system.
U.S. Pat. No. 7,150,664 discloses a steering actuator system for an outboard motor that connects an actuator member to guide rails, which are, in turn, attached to a motive member such as a hydraulic cylinder. The hydraulic cylinder moves along a first axis with the guide rail extending in a direction perpendicular to the first axis. An actuator member is movable along the guide rail in a direction parallel to a second axis and perpendicular to the first axis. The actuator member is attached to a steering arm of the outboard motor.
U.S. Pat. No. 7,255,616 discloses a steering system for a marine propulsion device that eliminates the need for two support pins and provides a hydraulic cylinder with a protuberance and an opening which cooperate with each other to allow a hydraulic cylinder's system to be supported by a single pin for rotation about a pivot axis. The single pin allows the hydraulic cylinder to be supported by an inner transom plate in a manner that it allows it to rotate in conformance with movement of a steering arm of a marine propulsion device.
U.S. Pat. No. 7,467,595 discloses a method for controlling the movement of a marine vessel including rotating one of a pair of marine propulsion devices and controlling the thrust magnitudes of two marine propulsion devices. 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 propulsion devices relative to its steering axis.
U.S. Pat. No. 8,046,122 discloses a control system for a hydraulic steering cylinder utilizing a supply valve and a drain valve. The supply valve is configured to supply pressurized hydraulic fluid from a pump to either of two cavities defined by the position of a piston within the hydraulic cylinder. A drain valve is configured to control the flow of hydraulic fluid away from the cavities within the hydraulic cylinder. The supply valve and the drain valve are both proportional valves in a preferred embodiment of the disclosed invention in order to allow accurate and controlled movement of a steering device in response to movement of a steering wheel of a marine vessel.
U.S. Pat. No. 8,512,085 discloses a tie bar apparatus for a marine vessel having at least first and second marine drives. The tie bar apparatus comprises a linkage that is geometrically configured to connect the first and second marine drives together so that during turning movements of the marine vessel, the first and second marine drives steer about respective first and second vertical steering axes at different angles, respectively.
U.S. patent application Ser. No. 14/177,762, filed Feb. 11, 2014, discloses a system for controlling movement of a plurality of drive units on a marine vessel having a control circuit communicatively connected to each drive unit. When the marine vessel is turning, the control circuit defines one of the drive units as an inner drive unit and another of the drive units as an outer drive unit. The control circuit calculates an inner drive unit steering angle and an outer drive unit steering angle and sends control signals to actuate the inner and outer drive units to the inner and outer drive unit steering angles, respectively, so as to cause each of the inner and outer drive units to incur substantially the same hydrodynamic load while the marine vessel is turning. An absolute value of the outer drive unit steering angle is less than an absolute value of the inner drive unit steering angle.
U.S. Pat. No. 7,527,538 discloses a small boat has multiple propulsion units. A toe angle of the multiple propulsion units can be altered while the boat is under way. The toe angle can be adjusted to improve performance in any of a number of areas, including top speed, acceleration, fuel economy, and maneuverability, at the demand of the operator.
U.S. patent application Ser. No. 14/843,439, filed Sep. 2, 2015 discloses systems and methods for reducing steering pressures of marine propulsion device steering actuators are disclosed. First and second sensors sense first and second conditions of first and second steering actuators. A third sensor senses an operating characteristic of the marine vessel. A controller is in signal communication with the first, second, and third sensors. In response to the marine vessel travelling generally straight ahead, the controller determines a target toe angle between the first and second marine propulsion devices based on the operating characteristic. The controller commands the first and second steering actuators to position the first and second marine propulsion devices at the target toe angle. The controller thereafter gradually adapts the target toe angle between the first and second marine propulsion devices until the controller determines that an absolute difference between the first condition and the second condition reaches a calibrated value.
U.S. patent application Ser. No. 14/960,551, filed Dec. 7, 2015 discloses a method of controlling steering loads on a marine propulsion system of a marine vessel. The marine vessel has at least two sets of marine drives, each set having at least an inner marine drive and an outer marine drive, and a steer-by-wire steering actuator is associated with each set of marine drives. The method includes determining a maximum required actuator pressure on each steer-by-wire steering actuator, and determining a pressure reduction amount based on the maximum required actuator pressure. A link toe angle has been determined based on the pressure reduction amount. A mechanical link connecting each inner marine drive to the respective outer marine drive is adjusted to achieve the link toe angle.
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 embodiment, a system for steering a marine vessel includes a first marine drive having a first engine control module and a second marine drive having a second engine control module, where the first and second marine drives are connected by a mechanical link. A first steer-by-wire steering actuator is configured to rotate the first and second marine drives to steer the marine vessel, and a first actuator control module controls the first steer-by-wire steering actuator. The system operates such that the first actuator control module activates the first steer-by-wire steering actuator if either the first marine drive or the second marine drive is running.
One embodiment of a method for controlling steering of a set of marine drives connected by a mechanical link includes receiving an engine speed of a first marine drive at an actuator control module that controls a steer-by-wire steering actuator, and receiving an engine speed of a second marine drive at the actuator control module. The method further includes determining that at least one of the first engine speed or the second engine speed is at least a threshold value, and activating the steer-by-wire steering actuator to rotate the first and second marine drives to steer the marine vessel.
The present disclosure is described with reference to the following Figures. The same numbers are used throughout the Figures to reference like features and like components.
In the present description, 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.
Each set of marine drives is connected together with a mechanical link 51, 52. In one example, the mechanical link is an adjustable tie bar, such as that described in U.S. Pat. No. 8,512,085; however, a person having ordinary skill in the art will understand in view of this disclosure that other mechanical link arrangements are appropriate. Mechanical link 51 connects the port inner marine drive 7 to the port outer marine drive 6. Likewise, the mechanical link 52 connects the inner starboard marine drive 8 to the outer starboard marine drive 9. The mechanical links 51, 52 maintain a set distance between the inner and outer marine drives in each set such that as one drive turns, the other drive in the set also turns in the same direction and by an equal amount. In other words, the inner marine drive and the outer marine drive of each set are steered together.
The sets of marine drives 6 and 7, 8 and 9 are capable of being steered separately to different angles. This allows the marine drives 6-9 to operate in many different modes, including in a joystick mode such as that described in U.S. Pat. No. 7,467,595 incorporated by reference herein above. While in joystick mode, each steer-by-wire steering actuator 12, 13 may rotate the associated set of marine drives 6 and 7, 8 and 9 independently of one another to different steering angles about their steering axes. In other modes, the two sets of drives 6 and 7, 8 and 9 may be operated simultaneously and symmetrically, with the steer-by-wire steering actuators 12 and 13 operating the respective sets of drives 6 and 7, 8 and 9 by rotating them in equal and opposite directions.
Equipping a marine vessel 2 with four drives provides increased propulsion power allowing for high speeds of travel, including upwards of 65 MPH or 90 MPH or higher, and/or for propelling heavy vessels 2. Traditionally, vessels provided with four or more drives have all four drives tied together, such as with a combination of tie bars and hydraulic hoses and actuators, so that all engines work and steer in unison. The tying of all four drives was required in prior art systems because the tie bars were needed to bear much of the pressure created by hydrodynamic forces on the drives when operating at high speeds and/or under heavy steering loads. Thus, prior art vessels with high speed capabilities could not be outfitted with joysticking capabilities because they could not offer the independent steering capabilities required.
Through their experimentation and research in the relevant field, the present inventors have recognized that it is desirable to provide a marine vessel 2 with four marine drives that can be operated in a joysticking mode. Operation in joysticking mode requires at least two drives that are steered independently of one another in order to provide sufficient flexibility and precision of propulsion forces, as described in U.S. Pat. No. 7,467,595 which is incorporated by reference above. Accordingly, operation in a joysticking mode requires a steer-by-wire system, where individual steering actuators separately control rotation of each set of marine drives, such as through hydraulic steering systems or combination electric/hydraulic steering systems. Since each set of marine drives is mechanically linked, only one steering actuator is used to drive each pair. One example of a steer-by-wire control system is provided at U.S. Pat. No. 7,941,253, which is hereby incorporated herein by reference. While in joysticking mode, each steer-by-wire steering actuator orients the associated marine drives independently of one another and to different steering angles in response to manipulation of an input device at the helm 42, such as steering wheel 41 or joystick 43.
The present inventors have also recognized that providing a high speed marine vessel with joysticking capabilities poses problems and challenges, specifically with respect to the steering system and to providing sufficient steering pressure with steer-by-wire steering actuators to steer the marine vessel 2 at high speeds. The inventors recognized that hydrodynamic forces on the marine drives 6-9 can overwhelm steering actuators associated therewith such that the steering actuator for the set of drives is incapable of providing sufficient hydraulic pressure to overcome the hydrodynamic forces and rotate the marine drives in order to effectively steer at high speeds. The inventors have recognized that this problem is especially acute in the presently disclosed system, where one steering actuator 12, 13 must produce sufficient force to steer two drives.
Additionally, a person having ordinary skill in the art will recognize in light of the present disclosure that the steering control methods and systems describe herein may apply equally to a propulsion system 1 having only one set of marine drives, and the set may include any number of two or more drives connected together by a mechanical link such that steering can be enacted by a single steering actuator. The depicted control arrangement may also apply to a marine vessel having three marine drives tied together and connected to a single steering actuator.
Hydrodynamic forces on the marine drives are caused both by the propellers of the propulsion devices themselves as they push against the water (herein after propeller pressure) and by water moving off the hull of the vessel 2 and subsequently hitting each marine drive (herein after hull displacement pressure). During operation, unbalanced propeller pressure and hull displacement pressure require very high contrasting forces to be exerted by the steering systems, and specifically the steering actuators 51, 52, in order to maintain the marine drives 6-9 at the desired steering angles. The high pressures can overwhelm the steering actuators, which may cause the marine vessel 2 to become unresponsive to steering inputs by an operator and may further cause steering diagnostic errors.
Certain hydrodynamic forces can be decreased by positioning the marine drives 6-9 at a particular toe angle. Applicant's co-pending application Ser. No. 14/177,762, filed Feb. 11, 2014, entitled “Systems and Methods for Controlling Movement of Drive Units on a Marine Vessel,” which was incorporated by reference herein above, discusses how marine propulsion devices, especially one provided in a pair, triple, or quad configuration, can be steered to different steering angles from one another so as to cause each of the propulsion devices to incur substantially the same hydrodynamic load while the marine vessel is turning. The '762 application does not, however, address the situation in which the marine vessel is traveling generally straight ahead. Applicant's co-pending application Ser. No. 14/843,439, filed Sep. 2, 2015, entitled “Systems and Methods for Continuously Adapting a Toe Angle Between Marine Propulsion Devices,” which was also incorporated by reference herein above, discusses a system having a pressure sensor in each steer-by-wire steering actuator that constantly monitors the pressure on the steering system and adjusts the toe angle of the drives in a closed-loop feedback control algorithm in order to minimize hydrodynamic forces on each marine drive.
However, the present inventors have recognized that simply controlling the toe angle of each drive 6-9 with a single steering actuator does not provide sufficient pressure relief to counteract the hydrodynamic forces on marine vessels at very high speeds. Further, the inventors have recognized that such forces can be transferred to, and at least partially counteracted by, a mechanical link 51, 52 between the inner and outer drives in a set. Moreover, the inventors have recognized that the forces can be further counteracted by connecting the drives with the mechanical link at a particular toe angle, thereby reducing inefficiencies in the steering system and illuminating possible diagnostic faults due to failure of the steering actuators to achieve the required counteracting steering forces. Accordingly, the inventors developed the present system that reduces the pressure on the steer-by-wire steering actuators 12, 13 wherein the four marine drives 6-9 are divided into two sets 6 and 7, 8 and 9, and each set is connected by a mechanical link 51, 52 that connects the inner and outer marine drives at a defined toe angle. Each set of marine drives 6 and 7, 8 and 9 can then be rotated by a single steering actuator to further adjust the toe position of the marine drives, such as to a greater positive toe angle, and to steer the marine vessel. The presently disclosed system with pairs of drives tied together has the added benefit that only one steering actuator 12, 13 is needed per set of drives, which provides for a simpler system and reduces costs.
For example, referring to
Referring again to
Each actuator 12, 13 is also associated with a switch 32 and 33, respectively, that selects which drive 6-9 powers the actuator 12, 13. Switch 32 alternately connects the actuator 12 to be powered by the battery 46 of inner port drive 6 or the battery 47 of outer port drive 7. Likewise, switch 33 alternately connects actuator 13 to battery 48 of inner starboard drive 8 or battery 49 of outer starboard drive 9. The switch may be any type of device capable of alternately making the electrical connection between the actuator 12, 13 and the respective one of the associated drives 6, 7 or 8, 9. In one exemplary embodiment, the switch 32 is an automatic transfer switch, such as the 895091K03 power switch assembly provided by Mercury Marine of Fond du Lac, Wis. In another embodiment, the switch 32, 33 could be a relay controlled by the respective actuator control module 22, 23, as is provided in the system diagram at
Each ACM 22, 23 functions to control the associated actuator 12, 13, and is provided with programming that executes the steering control methods. Upon startup, each ACM 22, 23 determines whether either one of its associated drives 6 or 7, 8 or 9 are functioning. If either drive is functioning, the ACM 22, 23 activates the steering actuator 12, 13, such as by powering on the actuator 12, 13 and preparing it to execute a steering command. Additionally, in an embodiment having electric over hydraulic steering actuation, the hydraulic pump may also be powered. Thus, if either marine drive in each set of marine drives 6 and 7, 8 and 9 is operating, then the set will be steered so that the functioning marine drive can be utilized for propelling and steering the marine drive 2, rather than shutting down both marine drives in the pair when only one is not operational. In the situation where one of the marine drives in a pair 6 and 7, 8 and 9 is not functioning, the switch 32, 33 would connect the actuator 12, 13 with the battery 46 or 47, 48 or 49, of the functioning marine drive. The ACM 22, 23 may determine the functioning state of its associated marine drives 6 and 7, 8 and 9 by communication with the respective ECM 36-39. For example, the ACM 22, 23 may receive the engine rpm of each of its respective drives from the ECMs 36 and 37, 38 and 39. In one embodiment, each set of marine drives may be connected to a single controller area network (CAN bus). Accordingly, ECM 36 and ECM 37 may transmit engine rpm values to ACM 22 via a first CAN bus, and ECM 38 and ECM 39 may transmit engine rpm value to ACM 23 via a second CAN bus. In an alternative embodiment, all ECMs and ACMs may be connected on a single CAN bus. For another embodiment, all modules on the vessel may be connected on a single CAN bus, and a redundant CAN bus may be provided for each branch (port and starboard) of the system. Thus, each module may be on two command-capable CAN busses. In another embodiment shown in
The ACM 22, 23 activates the respective steering actuator 12, 13 if the engine rpms are at least a threshold value. For example, the ACM 22, 23 may activate the steering actuator 12, 13 if either of its associated marine drives 6 or 7, 8 or 9 have at least a threshold engine speed of 400 rpm. In other embodiments, the threshold engine speed may be higher or lower. Depending on the drive type and construction, the engine may idle around 650 rpm. Certain events, such as shifting into a forward gear or a reverse gear, may cause the engine speed to dip below its idle speed. Thus, it may be preferable to set the threshold value below the engine idle speed so that false negatives are avoided. If the threshold rpm value is set too high, then the ACM 22, 23 may not activate the actuator 12, 13 when its associated marine drives 6 and 7, 8 and 9 are running, which would mean that the set of marine drives would not be steerable. Further, it is known that the starter may cause an engine to turn at a relatively low rpm, even if the engine does not actually fire up. For example, a starter may cause an engine to turn at up to 200 rpm. Thus, it may be desirable to set the threshold value above the maximum engine speed that may be induced by the starter alone so that false positives are avoided—i.e., the ACM 22, 23 can avoid activating the steering actuator 12, 13 falsely and draining the batteries 46 and 47, 48 and 49.
The embodiments of
Each marine drive 6-9 is controlled by a respective helm control module (HCM) 16-19. Each HCM 16-19 is communicatively connected to the engine control module (ECM) 36-39 to control the function of the respective marine drive 6-9. The dashed lines depicted in
In the embodiment of
In the instance of a malfunction or fault status of one of the steering actuators 12, 13, the respective ACM 22,23 will detect and communicate the steering fault status to the dominant HCM 17, 18 associated with the faulting actuator 12,13. For example, a steering fault status may arise if the steering actuator 12, 13 is unable to effectuate the steering command, such as not having the ability to provide the force necessary to execute the command, or if the steering actuator 12, 13 fails all together and can no longer operate. This steering fault status may then be communicated from the dominant HCM 17, 18 to the respective “slave” HCM 16, 19. Furthermore, the dominant HCM 17, 18 receiving the steering fault status may also communicate it to the other dominant HCM so that all of the HCMs are then aware of the steering fault status and can command accordingly. Depending on the cause or content of the communicated steering fault status, the HCMs may command accordingly. For example, if the steering fault status relates to insufficient power, then the dominant HCMs 17 and 18 may command that the drives 6-9 be toed to a greater toe angle. If the steering fault status relates to a failure of one of the steering actuators 12, 13, then the HCMs may adjust their steering algorithm to account for the inability to steer one set of marine drives.
In another embodiment similar to that depicted in
Each HCM 16-19, ACM 22, 23, and ECM 36-39 may include a computing system that includes a processing system, storage system, software, and input/output (I/O) interfaces for communicating with other devices, including the steering input devices at the helm 42, steering actuators 12, 13, and marine drives 6-9. The processing system loads and executes software from the storage system, including a software application module to control steering operations and the steering actuator. When executed by the computing system, the actuator control software application module directs the processing system to operate as described herein below in further detail to execute the method of controlling steering. While each HCM, ACM, and ECM is discussed herein as a single processing unit, one of ordinary skill in the relevant art will understand in light of the present disclosure that each HCM, ACM, and ECM may include one or many application modules and one or more processors, which may be communicatively connected. The processing system can comprise a microprocessor and other circuitry that retrieves and executes software from the storage system. Processing system can be implemented within a single processing device but can also be distributed across multiple processing devices or sub-systems that cooperate in executing program instructions. Non-limiting examples of the HCM, ACM, and ECM include general purpose central processing units, applications specific processors, and logic devices.
The storage system, which may be associated with each control module or jointly shared between control modules, can comprise any storage media readable by the processing system and capable of storing software. The storage system can include volatile and non-volatile, removable and non-removable media implemented in any method or technology for storage of information, such as computer readable instructions, data structures, program modules, or other data. The storage system can be implemented as a single storage device or across multiple storage devices or sub-systems. The storage system can further include additional elements, such as a controller capable of communicating with the processing system. Non-limiting examples of storage media include random access memory, read only memory, magnetic discs, optical discs, flash memory, virtual memory, and non-virtual memory, magnetic sets, magnetic tape, magnetic disc storage or other magnetic storage devices, or any other medium which can be used to store the desired information and that may be accessed by an instruction execution system. The storage media can be a non-transitory or a transitory storage media.
Besides the steering wheel 41 and the joystick 43, other user interfaces to provide steering control input could alternatively or additionally include a mouse, a keyboard, a voice input device, a touch input device (e.g., touch screen), and other comparable input devices and associated processing elements capable of receiving user input from an operator of the marine vessel 10. Output devices such as a video display or graphical display can display an interface further associated with embodiments of the system and method disclosed herein
In the depicted embodiment, each set of marine drives is configured with propellers moving in counter rotating directions to one another. Specifically, the outer port drive 6 has propeller 26 rotating in a counter clockwise direction, and inner port drive 7 has propeller 27 rotating in a clockwise position. Similarly, inner starboard drive 8 has propeller 28 rotating in a counter clockwise direction, and outer starboard drive 9 has propeller 29 in a clockwise direction. Thus, the two inner drives, 7 and 8, have propellers 27 and 28 that rotate in directions opposite from one another. Likewise, the two outer drives 6 and 9 have propellers 26 and 29 that rotate in directions that are opposite from one another. In another embodiment, the propellers 26-29 of each marine drive 6-9 may rotate in the opposite direction than that depicted in
Referring to
As is described above, the marine drives 6-9 experience pressure from hydrodynamic forces, including from hull displacement pressure and from propeller pressure. Hull displacement pressure 62 and propeller pressure 64 act on each marine drive 6-9. It should be understood that the hull displacement pressure 62 and the propeller pressure 64 vary with the speed of the vessel and speed of the propeller. The hull displacement and the propeller pressure at any particular speed can be added together using standard techniques of adding forces to determine the pressure on each marine drive 6-9 at that speed.
The pressures on the marine drives also vary with their steering positions, and must be counteracted in some way in order to manipulate and control the position of the marine drives 6-9 in order to steer the marine vessel 2. As the hydrodynamic pressures on the drives generally increase with speed, the amount of counteracting force required at high vessel speeds is much greater than at low vessel speeds. One way to counteract the forces is to mechanically tie, or link, each set of drives together to balance the opposing propeller pressures 64a and 64b, 64c and 64d.
Toe angle can also be used to counteract the forces on each set of marine drives 6 and 7, 8 and 9, and the corresponding pressure on the steering actuators 51, 52. The greater the magnitude of the unbalanced hull displacement pressures 62 and propeller pressures 64, the greater the toe angle needed to create counteracting toe pressure.
In one embodiment, the link toe angle θ may be calculated based on a pressure reduction amount needed on the steering actuator 12, 13. For example, the pressure reduction amount may be determined based on the maximum pressure expected on the steering actuator 12, 13, given the geometry and max speed of the boat, and the maximum output pressure available from the steering actuator 12, 13. For purposes of these calculations, it may be assumed that the pressures on the set of marine drives on either side of the centerline 10 are equal. Thus, in the depicted embodiment, each of the outer drives 6, 9 is assumed to experience the same pressure magnitude, albeit in opposite directions, and each of the inner marine drives 7, 8 is assumed to experience the same pressure magnitudes in opposite directions. Thus, the hull displacement pressure 62 and the propeller pressure 64 may be derived for each inner drive 7, 8 and each outer drive 6, 9.
In one embodiment, the hull displacement pressure and the propeller pressure on each of the inner drives 7, 8 and outer drives 6, 9 are determined as a function of speed. In general, one of skill in the art will understand that the maximum pressure on each drive 6-9 is not necessarily at the maximum speed of the vessel 2. In general, hull displacement pressure tends to decrease as a vessel 2 approaches its maximum speed, while the propeller pressure 64 tends to increase with speed. The propeller pressure and the hull displacement pressure may be summed to derive the pressure on each of the inner drives 7, 8 and outer drives 6, 9, as depicted in
A link toe angle θ is then calculated based on the pressure reduction amount. In one embodiment, a maximum outer toe angle and a maximum inner toe angle are calculated to achieve a total toe pressure equal to the pressure reduction amount. Preferably, each of the maximum inner toe angle and the maximum outer toe angle are between −3° and 3°. The link toe angle θ may then be calculated on the maximum inner and outer toe angles. In one embodiment, the link toe angle θ is calculated according to the following equation:
θ=(max outer toe angle−max inner toe angle)/2
The set of marine drives is then connected together to achieve the link toe angle. As depicted in
Each set of marine drives 6 and 7, 8 and 9 are then separately steerable, as described above. While in joysticking mode, it may be desirable to steer each set 6 and 7, 8 and 9 separately to different steering angles. However, when traveling straight ahead towards at high speeds and/or under high steering loads, it is desirable to rotate the sets 6 and 7, 8 and 9 in equal and opposite directions so that any lateral propulsion forces created by the drives are counteracted. At high speeds and/or high steering loads, the sets of marine drives 6 and 7, 8 and 9 may be positioned by the respective steering actuators 12, 13 in a positive toe, or “toe-in” position.
In the above description, 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 and are intended to be broadly construed. The different systems and method steps described herein may be used alone or in combination with other systems and methods. It is to be expected that various equivalents, alternatives and modifications are possible within the scope of the appended claims.
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| Entry |
|---|
| Pending U.S. Appl. No. 14/177,762, filed Feb. 11, 2014, Andrasko, entitled “Systems and Methods for Controlling Movement of Drive Units on a Marine Vessel”. |
| Pending U.S. Appl. No. 14/843,439, filed Sep. 2, 2015, Andrasko, entitled Systems and Methods for Continuously Adapting a Toe Angle Between Marine Propulsion Devices. |
| Pending U.S. Appl. No. 14/960,551, filed Dec. 7, 2015, Gable, entitled Methods and Systems for Controlling Steering Loads on a Marine Propulsion System. |
