Watercraft position management system & method

Abstract

Movement of a watercraft / vehicle is precisely controlled for operations such as docking, remaining on-station, and rotating about the craft's center of mass. The system uses the primary propulsion units used to operate the watercraft under normal conditions without the need for thrusters. Two or more primary propulsion units are controlled to move the watercraft / vehicle forward / aft, laterally, obliquely lateral and may include rotation as desired. One propulsion unit produces reverse thrust and one propulsion unit produces forward thrust while the propulsion angles of the propulsion units are controlled. A variable length draglink simplifies operation of the system. An engine control unit and user interface generate signals to control the thrust magnitude and propulsion angles of the propulsion units. Movement sensors provide data to the control unit for improved control of the watercraft / vehicle.

Description

BACKGROUND OF THE INVENTION [0001]The present invention relates primarily to propulsion control systems for watercraft. More specifically, the present invention relates to a method and apparatus for controlling multi-propulsion unit systems capable of precisely maneuvering watercraft using the primary propulsion units without the need for thrusters.[0002]In recent years, the popularity of watercraft for sport, recreation, and transportation has increased. As such, various systems for controlling and maneuvering watercraft have been developed. Prior art systems provide a simple means of controlling thrust and turning of a watercraft. More complex systems provide for additional maneuvering capabilities but are prohibitively expensive and typically require thrusters, cannot be easily retrofit to existing watercraft, or they are difficult to operate.[0003]With the increased popularity of watercraft as a sport and recreational activity, watercraft equipment has drastically increased in p...

AI Technical Summary

Benefits of technology

[0006]The aforementioned drawbacks and disadvantages of these prior art position management systems have been identified and a solution is set forth herein by the inventive position management system and method which comprises two propulsion units, a steering mechanism for controlling the propulsion angle of the propulsion units, and a unique method of manipulating thrust vectors to achieve precision maneuvering. Additionally the invention comprises art engine control unit for communicating propulsion angle commands and for communicating thrust commands for the at least two propulsion units; an operator interface for communicating operator commands; and movement sensors for communicating information on the motion of the craft. The preferred embodiment also includes a variable length draglink that simplifies controlling the propulsion angle of the propulsion units. The invention enables a watercraft to move forward / aft, laterally, obliquely lateral, with or without rotation such that docking the craft is much easier and more precise than the prior art.

[0007]One feature of the present invention is the variable length draglink that is coupled to the propulsion units. In the preferred embodiment, the draglink comprises a screw jack system comprising a jack screw and an electric motor. The electric motor turns the jack screw and thereby changes the length of the draglink. The length of the draglink controls the vector angle between the thrust vectors of the propulsion units and enables simple yet precise maneuvering of the craft. In the preferred embodiment, the draglink is shortened to increase the vector angle and, conversely, it is lengthened to decrease the vector angle. When the appropriate vector angle is achieved the thrust vectors from the propulsion units combine to yield a desired net thrust vector on the craft. An advantage of the draglink is that by controlling the length of the draglink, precision maneuvers are easily achieved. Precision maneuvers comprise rotation of the craft about a stationary point, lateral motion of the craft without forward velocity or rotation, obliquely lateral movement, and combinations of these maneuvers. An aspect of the invention is that it does not require independent steering of the propulsion units since the steering is accomplished with a draglink coupled to both propulsion units.

[0008]Another feature of the present invention is an engine control unit that generates thrust commands and propulsion angle commands to achieve desired maneuvers. Initial thrust commands and propulsion angles are preferably selected from predetermined data generated during sea trials. This predetermined data is stored in memory. The control unit uses these initial values as a “first guess” and then makes adjustments to the thrust and propulsion angles to compensate for environmental conditions such as wind, eddy currents, or the like that affect movement of the craft. Another aspect of the invention is that it simplifies the maneuvering process to such an extent that an engine control unit is not required for a basic installation of the system.

[0009]And still in another feature of the present invention is a single point user interface used to communicate the watercraft operator's commands. In the preferred embodiment the operator moves a joystick to communicate a desired movement of the craft in any direction. For example, rotation of the joystick indicates a desire to rotate the watercraft and movement of the joystick to the left or right indicate lateral movement to port and starboard respectively. The interface includes an on-station button to command the control unit to keep the watercraft at the current position. The joystick simplifies operation of the watercraft.

[0011]Another feature of the invention is that precision maneuvers can be achieved while the thrust magnitude of the propulsion units is equal but opposite. This is yet another simplifying aspect of the invention. Similarly, precision maneuvers can be achieved with propulsion angles that are equal but opposite. This is another simplifying aspect of the invention. These two features greatly simplify control of the craft.

[0012]To address the goals stated above, the inventive position management system and method combines the unique steering mechanism and the method of thrust and propulsion angle control to allow a watercraft to be easily and precisely maneuvered. By simplifying operation and improving control of a watercraft the inventive system reduces the risk of damage to watercraft and docks and reduces stress on the crew. The present invention is useful in many applications where a craft or vehicle benefits from improved and simplified control. While the primary application of the invention will likely be small to medium size twin engine watercraft, those skilled in the art understand that the invention is applicable to various other vehicles including, but not limited to, multi-engine watercraft, large ships, hovercraft, lighter than air ships, spacecraft, and aircraft. The invention may also be practiced with virtually any propulsion system including, but not limited to, inboard motors, outboard motors, propeller systems, jet drives, or even thrusters or rockets. Application of the invention is not limited to docking maneuvers but is also useful wherever precision control or maneuvering is desirable. For example, the invention is useful in remaining on-station, compensating for variable winds, eddy currents, and the like. Of course, this description is in no way meant to be limiting in any manner.

Problems solved by technology

More complex systems provide for additional maneuvering capabilities but are prohibitively expensive and typically require thrusters, cannot be easily retrofit to existing watercraft, or they are difficult to operate.

While these systems operate satisfactorily for propelling a watercraft in a substantially forward direction, they are less satisfactory in precisely maneuvering the watercraft in tasks such as docking, remaining on station, and generally maneuvering where precise control is desired.

Prior systems have used complicated schemes to overcome these deficiencies.

These systems are expensive, complicated, require much more attention of the operator, and often cause stress on the operator or crew.

In addition, the deficiencies in the current systems are a significant cause of damage to watercraft and docks.

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