Patent Publication Number: US-2023150643-A1

Title: Position hold to structure/object feature for thruster equipped watercraft

Description:
CROSS-REFERENCES TO RELATED APPLICATIONS 
     This patent application claims priority to U.S. Provisional Patent Application Ser. No. 63/280,573, filed Nov. 17, 2021 which is incorporated herein by reference in its entirety. 
    
    
     TECHNICAL FIELD 
     The disclosure herein relates to marine vessels and, more particularly, to systems and methods for holding position of a marine vessel using a maneuvering thruster system. 
     BACKGROUND 
     V-hull low-speed or no-speed lateral boat control often utilizes a bow and/or stern thruster. A thruster is a small ducted prop driven by an electric motor. Thrusters are mounted permanently into the bow of the boat near the keel (underwater). Thrusters allow an operator to control the position of the vessel by swinging the bow left and right while at dock, or in any other situation that calls for low speed maneuverability. This movement is perpendicular to the axis of travel offered by propulsion units, as thrusters are not used for forward propulsion. 
     Temporary docking is the act of maintaining a vessel position near a dock, pier, jetty, boat, and the like, for the purpose of boarding and/or off-boarding. Current marine vessel operators, for temporary docking, typically, hold the marine vessel by hand or utilizing lines (e.g., ropes and the like). Holding the marine vessel by hand involves extra crew members and may require the strength to hold the marine vessel as well as the attention of the person(s) involved to stay on task. The marine vessel may move around at a dock by the power of wind, current, wake, personnel movement within the marine vessel, and the like. Inattention or lack of strength can result in damage to the marine vessel or safety issues (e.g., pinches, falls, and the like), particularly when boarding and/or off-boarding. 
     Using lines requires extra time and crew to attach lines at the various points on the marine vessel and/or to a structure. Typically, the marine vessel is tied to the structure to keep a maximum distance with a cushioned, protective bumper used to maintain minimum distance. This movement can again result in damage or safety concerns (e.g., pinch points when approaching the minimum distance and large gaps when approaching or at the maximum distances). 
     SUMMARY 
     This disclosure relates to marine vessel control. 
     An aspect of the disclosed embodiments includes a method for marine vessel position control. The method includes: receiving a position hold signal from a human-machine interface of a marine vessel; in response to receiving the position hold signal, monitoring sensor data from at least one sensor; determining a hold position based at least on the monitored sensor data; and selectively controlling a thruster system of the marine vessel to hold the marine vessel in the hold position using the monitored sensor data. 
     Another aspect of the disclosed embodiments includes a system for marine vessel position control. The system includes a processor and a memory. The memory includes instructions that, when executed by the processor, cause the processor to: receive a position hold signal from a human-machine interface of a marine vessel; in response to receiving the position hold signal, monitor sensor data from at least one sensor; determine a hold position based at least on the monitored sensor data; and selectively control a thruster system of the marine vessel to hold the marine vessel in the hold position using the monitored sensor data. 
     Another aspect of the disclosed embodiments includes an apparatus for marine vessel position control. The apparatus includes a processor and a memory. The memory includes instructions that, when executed by the processor, cause the processor to: receive a position hold signal from a human-machine interface of a marine vessel, the position hold signal indicating at least a hold distance between the marine vessel and an object; in response to receiving the position hold signal, determine an initial distance between the marine vessel and the object using sensor data from one or more sensors; in response to the initial distance being greater than the hold distance, selectively control a thruster system of the marine vessel, using at least one thruster of the thruster system, to propel the marine vessel toward the object; wait a delay period; determine a current distance between the marine vessel and the object; and, in response to a determination that the current distance corresponds to the hold distance, selectively control the thruster system, using the at least one thruster, to hold the marine vessel in the hold position. 
     These and other advantages and features will become more apparent from the following description taken in conjunction with the drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The disclosure is best understood from the following detailed description when read in conjunction with the accompanying drawings. It is emphasized that, according to common practice, the various features of the drawings are not to-scale. On the contrary, the dimensions of the various features are arbitrarily expanded or reduced for clarity. 
         FIG.  1 A  is a front, elevation schematic illustration of a thruster system for a marine vessel according to the principles of the present disclosure. 
         FIG.  1 B  is a side, elevation, schematic illustration of the thruster system according to the principles of the present disclosure. 
         FIG.  2    is a schematic illustration of four of the thruster systems on a two-pontoon boat to show the thrust direction of each thruster system according to the principles of the present disclosure. 
         FIG.  3 A  is a diagram illustrating a first operating condition of the four thruster systems according to the principles of the present disclosure. 
         FIG.  3 B  is a diagram illustrating a second operating condition of the four thruster systems according to the principles of the present disclosure. 
         FIG.  3 C  is a diagram illustrating a third operating condition of the four thruster systems according to the principles of the present disclosure. 
         FIG.  3 D  is a diagram illustrating a fourth operating condition of the four thruster systems according to the principles of the present disclosure. 
         FIG.  4    is a schematic illustration of a three-pontoon boat to show thrust directions of each thruster system according to the principles of the present disclosure. 
         FIG.  5 A  is a perspective view of the thrust system according to one aspect of the disclosure according to the principles of the present disclosure. 
         FIG.  5 B  is an elevation view of the thrust system of  FIG.  5 A , with an outline of a pontoon tube according to the principles of the present disclosure. 
         FIG.  6 A  is a perspective view of the thrust system according to another aspect of the disclosure according to the principles of the present disclosure. 
         FIG.  6 B  is an elevation view of the thrust system of  FIG.  6 A , with an outline of a pontoon tube according to the principles of the present disclosure. 
         FIG.  7 A  is a perspective view of the thrust system according to another aspect of the disclosure according to the principles of the present disclosure. 
         FIG.  7 B  is an elevation view of the thrust system of  FIG.  7 A , with an outline of a pontoon tube according to the principles of the present disclosure. 
         FIG.  8 A  is a diagram of a portion of a bidirectional thrust system operating in a first rotational condition according to the principles of the present disclosure. 
         FIG.  8 B  is a diagram of the portion of the bidirectional thrust system operating in a second rotational condition according to the principles of the present disclosure. 
         FIG.  9    is a perspective view of the thrust system having a step pocket on an outer portion of a pontoon according to the principles of the present disclosure. 
         FIG.  10    is a diagram view of a bidirectional thrust system, according to one example according to the principles of the present disclosure. 
         FIG.  11    is a diagram view of a thrust system having a belt with a plurality of paddles along a periphery of a pontoon, according to the principles of the present disclosure. 
         FIG.  12    generally illustrates a controller according to the principles of the present disclosure. 
         FIGS.  13 A- 13 D  generally illustrate a thruster equipped marine vessel according to the principles of the present disclosure. 
         FIG.  14    generally illustrates an alternative thruster equipped marine vessel according to the principles of the present disclosure. 
         FIG.  15    generally illustrates an alternative thruster equipped marine vessel according to the principles of the present disclosure. 
         FIG.  16    generally illustrates an alternative thruster equipped marine vessel according to the principles of the present disclosure. 
         FIG.  17    is a flow diagram generally illustrating a marine vessel position hold method according to the principles of the present disclosure. 
         FIG.  18    is a flow diagram generally illustration an alternative a marine vessel position hold method according to the principles of the present disclosure. 
     
    
    
     DETAILED DESCRIPTION 
     Referring now to the Figures, where the invention will be described with reference to specific embodiments, without limiting same, exemplary embodiments of a maneuvering thruster system and method for shallow draft marine vessels are illustrated. 
     Referring to  FIGS.  1 A and  1 B , schematically illustrated is a thruster system for a marine vessel. The marine vessel may be any type of shallow draft marine vessel, such as a pontoon boat, for example. As shown, the pontoon does not penetrate the water surface to a large depth. The embodiments of the thruster system described herein provide operator control over maneuvers that are desired at or near a dock (or other low speed situation). Such maneuvers may include side-to-side movement that is perpendicular to a propeller direction of the marine vessel. Additionally, small radius rotation of the marine vessel are also controllable with the thruster system. These benefits are provided, while addressing the challenges posed by the aforementioned shallow depth that is available. 
     The thruster system includes a motor that is an electric motor, a driveshaft operatively driven by the electric motor, and a rotatable member driven by the driveshaft. In some embodiments, the motor may be a hydraulic, pneumatic, or other type of motor, so long as the motor can drive the driveshaft. The rotatable member is located within a pump housing. The pump housing includes an intake opening that is defined in a bottom portion of the pump housing. By locating the intake opening on the bottom portion of the pump housing, the low water depth penetration is nullified, as the water is taken vertically upward into the pump housing during rotation of the rotatable member. The pump housing also includes a discharge opening located on a side portion of the pump housing. Expulsion of the water through the discharge opening during operation of the pump creates a thrust force that is in a direction substantially perpendicular to the propeller direction of the marine vessel. 
     The overall thruster system may be mounted to any suitable portion of the marine vessel hull. As shown in the illustrated embodiment, the thruster system may be located within a thruster chamber of the pontoon. Alternatively, the thruster system may be mounted to a side of the pontoon. Regardless of the precise location of the thruster system, it is permanently mounted and does not require repeated manipulation to put it in place for operation. 
     Referring now to  FIG.  2   , a two-pontoon configuration is shown. Specifically, a first pontoon and a second pontoon are included. In the illustrated embodiment, each pontoon includes a pair of thruster systems. Each pair is spaced longitudinally along the pontoon from each other, but the discharge openings of each pair are oriented substantially parallel to each other, such that each thruster system is capable of providing a sideways directed thrust, i.e., substantially perpendicular relative to the main propeller thrust direction. It is to be appreciated that embodiments having thrust directed at non-perpendicular angles is contemplated. 
       FIGS.  3 A- 3 D  show four different operational conditions associated with the two-pontoon—and four thruster system—configuration of  FIG.  2   . In particular,  FIG.  3 A  illustrates both thrusters on the first pontoon being on and both thrusters on the second pontoon being off. This operational condition results in substantially translational movement of the marine vessel to one side (the right in the orientation of the Figures).  FIG.  3 B  illustrates both thrusters on the second pontoon being on and both thrusters on the first pontoon being off. This operational condition results in substantially translational movement of the marine vessel to the other side (the left in the orientation of the Figures).  FIG.  3 C  illustrates the forward thruster on the first pontoon and the rearward thruster on the second pontoon being on, with the rearward thruster on the first pontoon and the forward thruster on the second pontoon being off. This operational condition results in rotational movement of the marine vessel in a clockwise direction, as viewed in the Figures.  FIG.  3 D  illustrates the forward thruster on the first pontoon and the rearward thruster on the second pontoon being off, with the rearward thruster on the first pontoon and the forward thruster on the second pontoon being on. This operational condition results in rotational movement of the marine vessel in a counter-clockwise direction, as viewed in the Figures. 
     While the above operational situations are specific to a four thruster embodiment, it is to be understood that more or fewer thrusters may be included in other embodiments. Similarly, the thruster systems described herein are not limited to use with a two-pontoon boat, or even to a pontoon boat. For example, a three-pontoon configuration is illustrated in  FIG.  4   . In the three-pontoon configuration, the outer pontoons, referred to as a first pontoon and a second pontoon, each include at least one thruster system with respective discharge directions that are opposite to each other (i.e., outward from vessel). The middle pontoon, referred to herein as a third pontoon, includes a bi-directional (i.e., reversible) electrically driven thruster. In another embodiment, the third pontoon may include two unidirectional thrusters on opposite sides of the third pontoon. The other thrusters are unidirectional to avoid motor and component complexity. 
       FIGS.  5 A- 7 B  illustrate various embodiments of the thruster system. Each embodiment includes the driveshaft operatively coupling the electric motor to the rotatable member within the pump housing, an intake opening on the bottom portion of the housing, and a discharge opening on a lower side of the pump housing.  FIGS.  5  and  6    utilize a rotatable member that comprises an impeller.  FIG.  7    illustrates a thruster system relying on a turbine wheel as the rotatable member. 
       FIGS.  8 A and  8 B  illustrate a portion of the thruster system to show the bi-directional operational capability that may be utilized in some embodiments, as such capability may be effective on some hull configurations. In such embodiments, the openings (e.g., nozzles) are oriented in a downward angle, relative to horizontal. For example, the openings may be angled between 5-10 degrees downward in some embodiments, and at about  7  degrees in some embodiments. Thus, the reduction in thrust from the Coanda effect could be avoided. 
       FIG.  9    illustrates a stepped-hull pocket that allows for clean water flow over the intake at running speeds. The pedestal mount is a feature that ensures the motor and electric components are kept out of water even if the chamber housing leaks. 
     Some of the embodiments disclosed herein rely on a bottom suction/side discharge orientation. The water is pulled up vertically—or substantially—through the bottom of the hull into the housing, and then directed back down and discharged out of the housing substantially perpendicular to the side of the boat hull. This jet of water causes the boat to react by moving in the opposite direction. This discharge will be mounted very low in hull and ‘fan’ shaped in some embodiments to ensure underwater operation. The fan nozzle cross-sectional area may be equal to the rotatable member diameter area to help reduce flow restriction, or may be constricted to an amount to maximize thrust via the Venturi effect. 
       FIG.  10    illustrates an embodiment of the thruster system that has the intake and discharge below the waterline. In this embodiment, the thruster system may include a tubular housing coupled to the pontoon and at least one rotatable member disposed within the tubular housing. In some embodiments, the rotatable member is at least one bi-directional impeller that functions as an impeller in one direction of rotation and as a propeller in an opposite direction of rotation. As illustrated in  FIG.  10   , the tubular housing may define an upwardly extending recess. The recess includes a height that is greater than a cross-sectional width of the rotatable member in some embodiments. The recess may be defined in various locations, so long as it is between a first housing opening and a second housing opening. For example, the recess may be located in a generally center position below the electric motor and between the first housing opening and the second housing opening, as illustrated in  FIG.  10   . The recess is configured to house the least one rotatable member. In practice, the recess is configured to allow air to discharge out of the tubular housing via the first housing opening and/or the second housing opening, and allow the water to fill a volume inside the tubular housing and recess such that the rotatable member is continuously submerged in the water. 
     Referring further to  FIG.  10   , the tubular housing may have a first housing opening that is proximate a first pontoon edge, a second housing opening that is proximate a second pontoon edge. A length of the tubular housing is measured from the first housing opening to the second housing opening, wherein the length is substantially perpendicular to a longitudinal direction of the pontoon. In some embodiments, the first housing opening and the second housing opening may be at least one nozzle that is oriented in a marine vessel downward angle. For example, the openings may be angled between about 5-10 degrees in some embodiments, and at about 7 degrees in other embodiments, such that the reduction in thrust from the Coanda effect could be avoided. In practice, the first housing opening and the second housing opening may both operate as an intake and/or a discharge, depending on the rotation of the bi-directional impeller. It is generally contemplated that the tubular housing may include additional housing openings, such as a third housing opening and a fourth housing opening, or additional openings, so long as the housing openings may operate as the intake and/or the discharge. By defining a low intake and discharge, in tandem with the continuously submerged rotatable member, the thruster system is able to intake and discharge water below the water line without having to draw the water substantially upwards towards the rotatable member. 
     Referring again to  FIG.  10   , the thruster system may include a linear actuator. The linear actuator may be coupled to the drive shaft of the motor and to the tubular housing. In operation, the linear actuator can allow the tubular housing and the rotatable member coupled to the drive shaft to actively change position such that the rotatable member is continuously submerged in water. Additionally, the linear actuator may be configured to fully retract the tubular housing and the rotatable member to a non-use condition, wherein the tubular housing and the rotatable member are above the waterline in the non-use condition. 
       FIG.  11    illustrates an embodiment of the thruster system that includes a paddle wheel defined along an outside periphery of the pontoon and at least partially in operable contact with the water. In some embodiments, the paddle wheel includes a motor with an output shaft and a belt pulley, a belt disposed along the outside periphery of the pontoon, wherein the belt is driven by the motor via a coupling with the belt pulley, and a plurality of paddles coupled to an outside portion of the belt, as illustrated in  FIG.  11   . 
     The paddle wheel may be coupled to the outside periphery of the pontoon such that the belt is disposed on the pontoon and/or a belt guide coupled to the pontoon, the motor is proximate the pontoon, and the plurality of paddles are coupled to the belt. In this embodiment, a portion of the paddle wheel will be at least partially below the water level, such that belt and at least a portion of the paddles will be continuously in contact with the water when the boat is deployed in the water. In other configurations, the paddle wheel may be coupled to an interior shaft that is disposed within a cavity defined within the pontoon and is concentric with the pontoon. 
     In this configuration, the belt may be coupled to an outside periphery of the interior shaft, the plurality of paddles may be coupled to the belt and extend outward from the outside periphery of the interior shaft and towards an inside surface of the pontoon, and the motor may be disposed within the cavity. In yet other configurations, the paddle wheel may be mounted in a slot around the center axis of the pontoon, wherein the slot has a depth that is generally equal to a height of at least one paddle. It is generally contemplated that a plurality of paddle wheels may be disposed throughout the boat. For example, a paddle wheel may be disposed on a front and/or rear portion of a first pontoon and/or a second pontoon. 
     Referring further to  FIG.  11   , the paddle wheel is configured to move in a bi-directional manner, such that the paddle wheel may move in a clockwise or counter-clockwise direction. In particular, the output shaft of the motor is configured to rotate in a bi-directional manner (e.g., clockwise direction, counter-clockwise direction), which in turn, allows the belt and the plurality of paddles to travel in either a clockwise direction or counter-clockwise direction around the outside periphery of the pontoon. This movement of the paddle wheel causes the plurality of paddles to contact the water and generate a force, wherein the force causes the boat to move in an opposite direction. For example, the boat may have a first paddle wheel disposed on the front-portion of a first pontoon and a second paddle wheel disposed on the rear portion of a second pontoon, wherein the first paddle wheel is rotating in a clockwise direction and the second paddle wheel in a counter-clockwise direction, causing the boat to subsequently rotate, as illustrated in  FIG.  3 C . 
     In some embodiments, the systems and methods described herein may be configured to provide quick, automatic marine vessel positioning when in the vicinity of a docking structure or other object including other vessels. The systems and methods described herein may be configured to provide the automatic positioning without additional crew members. The systems and methods described herein may be configured to engage the automatic positioning to maintain a position until disengaged. 
     The systems and methods described herein may be configured to reduce or prevent hard contact with the structure. The systems and methods described herein may be configured to maintain the marine vessel position near the structure for easy boarding and/or off-boarding. The systems and methods described herein may be configured to reduce or eliminate the possibility of damage to the marine vessel or injury to the crew. 
     In some embodiments, the systems and methods described herein may be configured to use the thruster system described herein or other suitable thruster system. For example, the systems and methods described herein may be configured to use one or more of at least one bow thruster, at least one stern thruster, other suitable thrusters, or a combination thereof. 
     The systems and methods described herein may be configured to use a controlled axis, such as a port-starboard axis, as well as a central axis (e.g., which may allow the marine vessel to spin on center, as is generally illustrated in  FIGS.  13 A- 13 C ). 
     In some embodiments, the marine vessel may include a controller, such as controller  100 , as is generally illustrated in  FIG.  12   . The controller  100  may include any suitable controller, such as an electronic control unit or other suitable controller. The controller  100  may be configured to control, for example, the various functions of the marine vessel. The controller  100  may include a processor  102  and a memory  104 . The processor  102  may include any suitable processor, such as those described herein. Additionally, or alternatively, the controller  100  may include any suitable number of processors, in addition to or other than the processor  102 . 
     The memory  104  may comprise a single disk or a plurality of disks (e.g., hard drives), and includes a storage management module that manages one or more partitions within the memory  104 . In some embodiments, memory  104  may include flash memory, semiconductor (solid state) memory or the like. The memory  104  may include Random Access Memory (RAM), a Read-Only Memory (ROM), or a combination thereof. The memory  104  may include instructions that, when executed by the processor  102 , cause the processor  102  to, at least, control various aspects of the marine vessel. 
     The controller  100  may receive one or more signals from various measurement devices or sensors  106  indicating sensed or measured characteristics of the marine vessel. The sensors  106  may include any suitable sensors, measurement devices, and/or other suitable mechanisms. For example, the sensors  106  may include one or more, one or more handwheel position sensors or devices, one or more motor position sensor or devices, one or more position sensors or devices, one or more light detection and ranging (lidar) sensors, one or more radio detection and ranging (radar) sensors, one or more sound navigation and ranging (sonar) sensors, one or more optical sensors, one or more image capturing sensors, one or more real-time kinematic (RTK) sensors, one or more global positioning system (GPS) sensors, one or more global navigation satellite system (GNSS) sensors other suitable sensors or devices, or a combination thereof. 
     In some embodiments, the sensors  106  may be configured to interact with at least one RTK base and/or at least one target, such as a reflective target, a magnetic target, a hi-contrast target, a radio-frequency target, a radio-frequency identification target, other suitable target, or a combination thereof. 
     In some embodiments, the controller  100  may interact with a human machine interface (HMI)  110 . The HMI  110  may include any suitable HMI, such as a switch, a dial, an interactive display, and the like. The HMI  110  may be disposed within the marine watercraft in a location suitable for interaction with the HMI  110  by an operator of the marine watercraft, as is generally illustrated in  FIGS.  14 - 16   . 
     In some embodiments, as is generally illustrated in  FIGS.  14 - 16   , the sensors  106  may be mounted on an outer perimeter of the marine vessel directed outboard. When the operator engages the HMI  110 , the controller  100  may be configured to monitor the sensors  106 , which may be configured detect the distance to the structure, such as the dock or other suitable structure or object. 
     The controller  100  may use thrusters  108 , based on sensor data received from the sensors  106 , to maintain the orientation of the marine vessel and the desired distance from the structure. The thrusters  108  may be disposed in any suitable location on the marine vessel, such as proximate a bow of the marine vessel, proximate a stern of the marine vessel, and/or other suitable location, as is illustrated in  FIGS.  13 A- 13 D  and  FIGS.  14 - 16   . Additionally, or alternatively, the thrusters  108  may include any suitable thrusters, such as those described herein. 
     The controller  100  may determine whether the marine vessel is too close (e.g., within a threshold distance) to the structure. The controller  100  may actuate or engage one or more thrusters  108  (e.g., directed in a corresponding direction), to distance the marine vessel from the structure. Alternatively, if the controller  100  determines that the marine vessel is too far from the structure, the controller  100  may actuate or engage one or more thrusters  108  (e.g., directed in a corresponding direction), to move the marine vessel closer to the structure. 
     In some embodiments, the operator can set a desired distance from the structure. This distance could be set to allow for easy boarding and/or off-boarding and may be ‘taught’ to the controller  100  and stored in the memory  104  or other suitable memory, prior to engaging the HMI  110 . 
     In some embodiments, the controller  100  may receive a position hold signal from the HMI  110  of the marine vessel. The position hold signal may indicate at least a hold distance between the marine vessel and an object. 
     The controller  100  may, in response to receiving the position hold signal, determine an initial distance between the marine vessel and the object using sensor data from one or more sensors  106 . 
     The controller  100  may, in response to the initial distance being greater than the hold distance, selectively control at least one thruster  108  to propel the marine vessel toward the object. 
     The controller  100  may wait a delay period (e.g., to account for unintended or delayed reaction movement of the marine vessel on the water). 
     The controller  100  may determine a current distance between the marine vessel and the object. 
     The controller  100  may, in response to a determination that the current distance corresponds to the hold distance, selectively control the at least one thruster  108  to hold the marine vessel in the hold position. 
     In some embodiments, the one or more sensors includes at least one sensor disposed on the object and at least one sensor disposed on the marine vessel. 
     In some embodiments, the controller  100  may use the sensors  106  to interact with one or more targets, as described. The controller  100  may detect the locations of the targets using the sensors  106 . The controller  100  may use the thrusters  108  to control the position of the marine vessel based on the detected target (e.g. to re-orient the marine vessel to the ‘proper’ predetermined orientation that facilitates the loading and/or off-loading of crew and/or gear and to maintain orientation). 
     In some embodiments, the controller  100  may use the sensors  106  to detect a RTK base mounted in the vicinity of the marine vessel. For example, the sensors  106  may include one or more rovers mounted to the marine vessel, as is generally illustrated in  FIG.  16   . The controller  100  may, based on the position information provided by the sensors  106  (e.g., the rovers), hold the position of the marine vessel using the thrusters  108 , as described. As described, the operator can set a desired distance from the structure. This distance could be set to allow for easy boarding and/or off-boarding and may be ‘taught’ to the controller  100  and stored in the memory  104  or other suitable memory, prior to engaging the HMI  110 . 
     In some embodiments, the controller  100  may be configured to, using the thrusters  108 , hold the position of the marine vessel based on the location of the RTK base. In some embodiments, the marine vessel may include two rover units installed on the marine vessel at a distance from each other to allow for proper orientation of the marine vessel in relation to its position. 
     In some embodiments, the controller  100  may selectively control position of the marine vessel using the thrusters  108  and/or a main propulsion unit (e.g., forward/reverse), which may allow the main propulsion unit to control another axis of control and the bow and stern orientation/position can be maintained. The marine vessel may include electronic shifting, and/or electronic throttle, and/or electronic steering to allow for the main propulsion unit to be used to control the position of the marine vessel, as described. 
     In some embodiments, the controller  100  may control positioning of the marine vessel (e.g., moving the marine vessel closer to or further away from the structure or object, as described, using the thrusters  108  and/or main propulsion unit) and/or may hold the position of the marine vessel using two or more sensors (e.g., including one or more of the sensors  106  and/or one or more other sensors), such as GPS, RTK, LIDAR, RADAR, proximity sensors mounted on the marine vessel and on mating features including but limited to items such as a dock, bouy, other vessel, trailer, hoist, vehicle, shore, other structure, other object, and/or person. For example, the controller  100  may receive data from the sensors indicating a starting position identified by the operator on the HMI  110 . 
     The starting sensor position or location may be provided controller  100  as input via the HMI  110  or any analog or digital signal method including manual switches, ISO CAN messages, blue tooth signals, and/or wireless signals from devices such as mobile computing devices, vehicle controllers, and/or other suitable computing devices. An end point sensor position or location may be provided as input the controller  100  via the HMI  110  or any analog or digital signal method including manual switches, ISO CAN messages, and blue tooth signals, and/or wireless signals from devices such as mobile computing devices, vehicle controllers, and/or other suitable computing devices. 
     In some embodiments, the controller  100 , in response to receiving the starting and end point position sensor information, may calculate a positive position and/or a negative position. The controller  100  may calculate a difference between the positive position and the negative position and a direction (e.g., right or left) between the starting point sensor location and the end point sensor location. The controller  100  may use the difference and direction to calculate a gap or distance between the two sensors. The controller  100  may determine which of the thrusters  108  to control (e.g., including controlling direction, water volume, and/or any other suitable aspect of the thrusters  108 ) to reduce the direction and difference between the two sensors to zero (e.g., or substantially zero) or other suitable value (e.g., such as a desired distance between the marine vessel and the structure or object). 
     The controller  100  may control the determined thrusters  108  to achieve the reduction in direction and difference. For example, the controller  100  may use a set of thruster gain adjustment tables (e.g., storing data corresponding to thruster gain adjustments) to modulate the amount of time the determined thrusters  108  are on to decrease the gap, distance, and direction between the starting position sensor and the end position sensor (e.g., where a high gain setting corresponds to a relatively long thruster on time, and a low gain setting corresponds to a relatively short thruster on time). The thruster on time may be modulated by the gain table selected by the operator. A frequency used, by the controller  100 , to calculate the distance and direction differential may include a frequency preset during a setup operation or set by the operator while operating the marine vessel. 
     In some embodiments, in response to the differential gap and position is zero (e.g., or substantially zero) or other suitable value, the controller  100  may modulate an on and/or off time of the determined thrusters  108  to maintain a zero (e.g. or other suitable value) difference between all sensors. The controller  100  may continue to calculate the difference between the starting position sensor and the end position sensor until the starting and end position sensors are at zero (e.g., or other suitable value) for an operator defined time. 
     In some embodiments, the controller  100  may communicate with two or more paired GPS pendant sets. One of the paired sets may include a pendant disposed on the fixed structure with another pendant mounted or disposed on the front or other suitable location of the marine vessel. Additionally, or alternatively, another paired set may include one pendent disposed on the fixed structure and another pendent mounted or disposed on the rear of the marine vessel (e.g., or other suitable location). It should be understood that, while limited examples are provided, the pendent sets may be disposed in any suitable location including and/or instead of those described herein. 
     Each pendent set would provide, to the controller  100 , distance and/or position information. The controller  100  may use the distance and position information to selectively control one or more of the thrusters  108 , as described, to move the marine vessel to a desired location relative to the fixed structure (e.g., or other object) and/or to hold the marine vessel at a desired location. 
     In some embodiments, a base (attached to a fixed object) of a pendent set may determine position information for the pendent attached to the fixed object using GPS coordinate information. The paired pendent disposed on the marine vessel may determine an initial position based on GPS coordinates and may, subsequently, use the base pendant (e.g., attached to the fixed object) as a comparison (e.g., to determine the position of the marine vessel relative to the base pendant). The controller  100  may use any method (e.g., including the method  300  described with respect to  FIG.  18   ) described herein to maintain a position of the marine vessel. 
     In some embodiments, the base pendants and/or the pendants disposed on the marine vessel may be temporarily attached to the fixed object (e.g., magnetically, if shielded, via a hanging lanyard, integrated into a cushion and/or bumper, and/or using any other suitable technique) or by other means or permanently attached to the fixed object (e.g., using an adhesive, embedding the pendant into a portion of the structure or object, and the like). 
     In some embodiments, the controller  100  may be configured to assist in trailering the marine vessel. For example, the controller  100  may use information from one or more pendant sets (e.g., disposed on the marine vessel and an associated trailer), reflectors mounted on the trailer, and the like to determine one or more positions of the marine vessel relative to the trailer. 
     In some embodiments, the controller  100  may use the sensors  106  to generate a rendering of the marine vessel and its position to its surroundings. The controller  100  may display the rendering in real-time at the helm on a multi-function display (MFD), other specialized HMI, or any suitable display. This may aid the operator in manual control of the marine vessel and/or verification of its position. It should be understood that the HMI could be mounted at helm, and/or incorporated into the MFD, and/or worn as pendant/belt on operators person, and/or be available on mobile computing device (e.g., such as using a mobile application). In some embodiments, the controller  100  may control position of the marine vessel further using an application on a mobile computing device in order to use WI/FI, and/or cellular data transition to forward notifications about position of the marine vehicle, much like an alarm if limits are reached, and/or to log position to verify position and a condition of the marine vessel. 
     In some embodiments, the controller  100  may perform the methods described herein. However, the methods described herein as performed by the controller  100  are not meant to be limiting, and any type of software executed on a controller or processor can perform the methods described herein without departing from the scope of this disclosure. For example, a controller, such as a processor executing software within a computing device, can perform the methods described herein. 
       FIG.  17    is a flow diagram generally illustrating a marine vessel position hold method  200  according to the principles of the present disclosure. At  202 , the method  200  receives a position hold signal from a human-machine interface of a marine vessel. For example, the controller  100  may receive the position hold signal from the HMI  110 . 
     At  204 , the method  200 , in response to receiving the position hold signal, monitors sensor data from at least one sensor. For example, the controller  100  may, in response to receiving the position hold signal, monitor the sensor data from the sensors  106 . 
     At  206 , the method  200  determines a hold position based at least on the monitored sensor data. For example, the controller  100  may determine the hold position based at least on the monitored sensor data. 
     At  208 , the method  200  selectively controls a thruster system of the marine vessel to hold the marine vessel in the hold position using the monitored sensor data. For example, the controller  100  may selectively control the thruster system of the marine vessel to hold the marine vessel in the hold position using the monitored sensor data. 
       FIG.  18    is a flow diagram generally illustrating an alternative marine vessel position hold method  300  according to the principles of the present disclosure. In some embodiments, the controller  100  may be configured to provide a delay feature. For example, motion on water is relatively difficult to achieve due to a delayed response to steering and/or propulsion inputs (e.g., marine vessels often appear sluggish and are slow to change direction due to the inherent damping property of water). This may result in unpredictable outcomes and over-correction with human operators. The controller  100  may be configured to perform a control loop algorithm that allows for a closed loop operation. 
     The delay (td) may be added to various control inputs to compensate for the increased inertial mass of the marine vessel and/or object under control and the delayed reactions. This may allow the controller  100  to behave in a “de-tuned” manner for improved performance and to avoid system over-shoot (e.g., which may be a relatively common issue with on-water navigation and control). The delay period may be increased or decreased as appropriate to maintain smooth motion. The controller  100  may be calibrated for the mass and geometry of the marine vessel and/or object under control (e.g., including the addition of mass resulting from passengers and/or cargo, which may be detected by the controller  100  using suitable weight or other sensors). 
     In some embodiments, the controller  100  may check a distance between the marine vessel and an object. The controller  100  may run or operate one or more appropriate thrusters  108  for a set period (t r ) to attempt the adjustment of the marine vessel to proper and/or desired distance from object. The controller  100  may delay for a set period (t d ). The controller  100  may, for each subsequent operation, adjust the set period (t r ) and the set delay (t d ) to increase or decrease the motion. This will be based on the distance-to-go to achieve proper position. 
     For example, at  302 , the method  300  sets an initial delay value (t 0 ) (e.g., using any suitable input or set value). For example, the controller  100  may set the initial delay value. 
     At  304 , the method  300  may engage a hold operation (e.g., to hold a position of the marine vessel). For example, the operator may use a switch, button, or other suitable analog or digital mechanism to engage the hold operation. A signal may be received by the controller  100  indicating the operator desire to engage the hold operation. The controller  100  may initiate the hold operation. 
     At  306 , the method  300  checks a distance to an object. For example, the controller  100  may check a distance between the marine vessel and a desired or selected object (e.g., using any suitable sensors or information described herein). 
     At  308 , the method  300  determines whether the object is detected. For example, the controller  100  may determine whether the object is detected using any suitable sensor or other information described herein. If the controller  100  detects the object, the method  300  continues at  310 . Alternatively, if the controller  100  does not detect the object, the method  300  continues at  304 . 
     At  310 , the method  300  determine whether a distance has been maintained. For example, the controller  100  determines whether a distance between the marine vessel and the object is maintained. If the controller  100  determines the distance is maintained, the method  300  continues at  318 . Alternatively, if the controller  100  determines that the distance is not maintained, the method  300  continues at  312 . 
     At  312 , the method  300  determines whether the hold operation is engaged. For example, the controller  100  may determine whether the hold operation is engaged. If the controller  100  determines that the hold operation is not engaged, the method  300  continues at  320 . Alternatively, if the controller  100  determines that the hold operation is engaged, the method  300  continues at  314 . 
     At  314 , the method  300  activates propulsion for a period (t r ). For example, the controller  100  may control one or more thrusters  108  to propel the marine vessel for the period (t r ). 
     At  316 , the method  300  applies a delay for a period (t d ). For example, the controller  100  may apply the delay for the period (t d ), which may include waiting the period (t d ). 
     At  318 , the method  300  checks a distance between the marine vessel and the object. For example, the controller  100  may determine a distance between the marine vessel and the object (e.g., structure or other object). The method  300  continues at  310 . 
     At  320 , the method  300  stops. For example, the controller  100  may disengage the hold operation. 
     In some embodiments, a method for marine vessel position control includes: receiving a position hold signal from a human-machine interface of a marine vessel; in response to receiving the position hold signal, monitoring sensor data from at least one sensor; determining a hold position based at least on the monitored sensor data; and selectively controlling a thruster system of the marine vessel to hold the marine vessel in the hold position using the monitored sensor data. 
     In some embodiments, the at least one sensor includes at least one of a light detection and ranging sensor, a radio detection and ranging sensor, a sound navigation and ranging sensor, an optical sensor, at least one pendant set, and an image capturing senor. In some embodiments, the at least one sensor includes at least one of a real-time kinematic sensor, a global positioning system sensor, and a global navigation satellite system sensor. In some embodiments, the at least one sensor is configured to interact with at least one real-time-kinematic base. In some embodiments, the at least one sensor is configured to interact with at least one target. In some embodiments, the at least one target includes at least one of a reflective target, a magnetic target, a hi-contrast target, a radio-frequency target, and a radio-frequency identification target. In some embodiments, the thruster system includes at least one thruster disposed on the marine vessel. In some embodiments, the at least one thruster is disposed proximate a bow of the marine vessel. In some embodiments, the at least one thruster is disposed proximate a stern of the marine vessel. 
     In some embodiments, a system for marine vessel position control includes a processor and a memory. The memory includes instructions that, when executed by the processor, cause the processor to: receive a position hold signal from a human-machine interface of a marine vessel; in response to receiving the position hold signal, monitor sensor data from at least one sensor; determine a hold position based at least on the monitored sensor data; and selectively control a thruster system of the marine vessel to hold the marine vessel in the hold position using the monitored sensor data. 
     In some embodiments, the at least one sensor includes at least one of a light detection and ranging sensor, a radio detection and ranging sensor, a sound navigation and ranging sensor, an optical sensor, at least one pendant set, and an image capturing senor. In some embodiments, the at least one sensor includes at least one of a real-time kinematic sensor, a global positioning system sensor, and a global navigation satellite system sensor. In some embodiments, the at least one sensor is configured to interact with at least one real-time-kinematic base. In some embodiments, the at least one sensor is configured to interact with at least one target. In some embodiments, the at least one target includes at least one of a reflective target, a magnetic target, a hi-contrast target, a radio-frequency target, and a radio-frequency identification target. In some embodiments, the thruster system includes at least one thruster disposed on the marine vessel. In some embodiments, the at least one thruster is disposed proximate a bow of the marine vessel. In some embodiments, the at least one thruster is disposed proximate a stern of the marine vessel. 
     In some embodiments, an apparatus for marine vessel position control includes a processor and a memory. The memory includes instructions that, when executed by the processor, cause the processor to: receive a position hold signal from a human-machine interface of a marine vessel, the position hold signal indicating at least a hold distance between the marine vessel and an object; in response to receiving the position hold signal, determine an initial distance between the marine vessel and the object using sensor data from one or more sensors; in response to the initial distance being greater than the hold distance, selectively control a thruster system of the marine vessel, using at least one thruster of the thruster system, to propel the marine vessel toward the object; wait a delay period; determine a current distance between the marine vessel and the object; and, in response to a determination that the current distance corresponds to the hold distance, selectively control the thruster system, using the at least one thruster, to hold the marine vessel in the hold position. 
     In some embodiments, the one or more sensors includes at least one sensor disposed on the object and at least one sensor disposed on the marine vessel. 
     The above discussion is meant to be illustrative of the principles and various embodiments of the present invention. Numerous variations and modifications will become apparent to those skilled in the art once the above disclosure is fully appreciated. It is intended that the following claims be interpreted to embrace all such variations and modifications. 
     The word “example” is used herein to mean serving as an example, instance, or illustration. Any aspect or design described herein as “example” is not necessarily to be construed as preferred or advantageous over other aspects or designs. Rather, use of the word “example” is intended to present concepts in a concrete fashion. As used in this application, the term “or” is intended to mean an inclusive “or” rather than an exclusive “or”. That is, unless specified otherwise, or clear from context, “X includes A or B” is intended to mean any of the natural inclusive permutations. That is, if X includes A; X includes B; or X includes both A and B, then “X includes A or B” is satisfied under any of the foregoing instances. In addition, the articles “a” and “an” as used in this application and the appended claims should generally be construed to mean “one or more” unless specified otherwise or clear from context to be directed to a singular form. Moreover, use of the term “an implementation” or “one implementation” throughout is not intended to mean the same embodiment or implementation unless described as such. 
     Implementations of the systems, algorithms, methods, instructions, etc., described herein can be realized in hardware, software, or any combination thereof. The hardware can include, for example, computers, intellectual property (IP) cores, application-specific integrated circuits (ASICs), programmable logic arrays, optical processors, programmable logic controllers, microcode, microcontrollers, servers, microprocessors, digital signal processors, or any other suitable circuit. In the claims, the term “processor” should be understood as encompassing any of the foregoing hardware, either singly or in combination. The terms “signal” and “data” are used interchangeably. 
     As used herein, the term module can include a packaged functional hardware unit designed for use with other components, a set of instructions executable by a controller (e.g., a processor executing software or firmware), processing circuitry configured to perform a particular function, and a self-contained hardware or software component that interfaces with a larger system. For example, a module can include an application specific integrated circuit (ASIC), a Field Programmable Gate Array (FPGA), a circuit, digital logic circuit, an analog circuit, a combination of discrete circuits, gates, and other types of hardware or combination thereof. In other embodiments, a module can include memory that stores instructions executable by a controller to implement a feature of the module. 
     Further, in one aspect, for example, systems described herein can be implemented using a general-purpose computer or general-purpose processor with a computer program that, when executed, carries out any of the respective methods, algorithms, and/or instructions described herein. In addition, or alternatively, for example, a special purpose computer/processor can be utilized which can contain other hardware for carrying out any of the methods, algorithms, or instructions described herein. 
     Further, all or a portion of implementations of the present disclosure can take the form of a computer program product accessible from, for example, a computer-usable or computer-readable medium. A computer-usable or computer-readable medium can be any device that can, for example, tangibly contain, store, communicate, or transport the program for use by or in connection with any processor. The medium can be, for example, an electronic, magnetic, optical, electromagnetic, or a semiconductor device. Other suitable mediums are also available. 
     The above-described embodiments, implementations, and aspects have been described in order to allow easy understanding of the present invention and do not limit the present invention. On the contrary, the invention is intended to cover various modifications and equivalent arrangements included within the scope of the appended claims, which scope is to be accorded the broadest interpretation so as to encompass all such modifications and equivalent structure as is permitted under the law. 
     While the invention has been described in detail in connection with only a limited number of embodiments, it should be readily understood that the invention is not limited to such disclosed embodiments. Rather, the invention can be modified to incorporate any number of variations, alterations, substitutions or equivalent arrangements not heretofore described, but which are commensurate with the spirit and scope of the disclosure. Additionally, while various embodiments of the disclosure have been described, it is to be understood that aspects of the disclosure may include only some of the described embodiments. Accordingly, the disclosure is not to be seen as limited by the foregoing description.