Patent Grant
12365425
The present disclosure generally relates to foil-assisted marine vessels, and particularly to systems and methods for mitigating the effects of an emergency splashdown event for foil-assisted marine vessels.
U.S. Pat. No. 3,800,727 discloses a control system for a hydrofoil characterized in that a transition from the foil-borne to the hull-borne mode of operation is initiated and the craft caused to descend or land automatically before an unsafe foil-borne roll or yaw attitude can be developed. This is achieved by providing an auxiliary electronic power source and auxiliary servo feedbacks in parallel with the main feedbacks for the control surface servos of the hydrofoil. The auxiliary feedbacks provide means for positioning the control surfaces to automatically land the craft upon the occurrence of a failure in the primary power source for the hydrofoil or some other off-normal condition.
U.S. Pat. No. 3,886,884 discloses a control system for a hydrofoil of the type having forward and aft submerged foils for supporting the craft while foil borne. In the preferred embodiment of the invention, separate pairs of starboard and port control flaps are provided on the aft foil; while the forward foil, also provided with flap means, is carried at the lower end of a pivoted strut which acts as a rudder. The system incorporates a high degree of redundancy for safety and failproof operation. Craft motions are sensed by gyroscopes and accelerometers which produce signals for controlling the flaps to provide smooth riding characteristics and a minimum of acceleration on passengers and crew for all seaway conditions. Turning of the craft is achieved by initially activating the flaps to bank the craft about its roll axis, followed by a rudder action. Pitch is controlled by both the forward and aft flaps; motions about the roll axis are controlled by the aft flaps only; while the height of the craft while foil-borne is controlled by the forward flap means only.
U.S. Pat. No. 6,273,771 discloses a control system for a marine vessel incorporating a marine propulsion system that can be attached to a marine vessel and connected in signal communication with a serial communication bus and a controller. A plurality of input devices and output devices are also connected in signal communication with the communication bus and a bus access manager, such as a CAN Kingdom network, is connected in signal communication with the controller to regulate the incorporation of additional devices to the plurality of devices in signal communication with the bus whereby the controller is connected in signal communication with each of the plurality of devices on the communication bus. The input and output devices can each transmit messages to the serial communication bus for receipt by other devices.
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 marine propulsion system for a hydrofoil marine vessel includes at least one marine propulsion device, a foil structure configured to raise at least a portion of a hull of the hydrofoil marine vessel system above a waterline when the hydrofoil marine vessel is operating in a foiling mode, and a propulsion controller operably coupled to the at least one marine propulsion device and the foil structure. The propulsion controller is configured to detect a loss of lift event in the foil structure during operation of the hydrofoil marine vessel in the foiling mode. Responsive to detection of the loss of lift event, the propulsion controller is configured to control the at least one marine propulsion device to increase a thrust provided by the at least one marine propulsion device.
In one example, the loss of lift event comprises a structural failure of the foil structure indicating a loss of lift supporting the hydrofoil marine vessel. In another example, the loss of lift event comprises a communications failure of the foil structure indicating a loss of lift supporting the hydrofoil marine vessel.
In one example, increasing the thrust comprises operating the at least one marine propulsion device at a predetermined percentage of a maximum thrust capacity. In one example, the predetermined percentage is 100%. In another example, increasing the thrust comprises operating the at least one marine propulsion device at less than 100% of a maximum thrust capability.
In one example, the control system is further configured to detect a velocity of the hydrofoil marine vessel in the foiling mode, and the increase in thrust provided by the at least one marine propulsion device is based at least in part on the velocity of the hydrofoil marine vessel in the foiling mode.
In one example, the control system is further configured to decrease the thrust provided by the at least one marine propulsion device after meeting a thrust increase condition until a velocity of the hydrofoil marine vessel reaches a predetermined safe velocity.
In one example, controlling the at least one marine propulsion device to increase the thrust comprises transmitting a high priority message to the at least one marine propulsion device over a controller area network to immediately increase propulsion output.
In one example, detecting the loss of lift event in the lifting foil is based on a change in at least one of a velocity, acceleration, or jerk of the hydrofoil marine vessel exceeding a predetermined threshold.
In one example, increasing the thrust provided by the at least one marine propulsion device comprises controlling revolutions per minute of a propulsor driveshaft as a control variable. In another example, increasing the thrust provided by the at least one marine propulsion device comprises controlling a torque output as a control variable. In yet another example, increasing the thrust provided by the at least one marine propulsion device comprises controlling a throttle position as a control variable. In yet another example, increasing the thrust provided by the at least one marine propulsion device comprises controlling a current consumed by a motor as a control variable.
According to another implementation of the present disclosure, a method of operating a marine propulsion system for a hydrofoil marine vessel includes detecting a loss of lift event in a foil structure during operation of the hydrofoil marine vessel in a foiling mode. The foil structure is configured to raise at least a portion of a hull of the hydrofoil marine vessel system above a waterline when the hydrofoil marine vessel is operating in a foiling mode. The method further comprises controlling at least one marine propulsion device to increase a thrust provided by the at least one marine propulsion device responsive to detection of the loss of lift event.
Various other features, objects, and advantages of the invention will be made apparent from the following description taken together with the drawings.
The present disclosure is described with reference to the following Figures.
Hydrofoil marine vessels include foils, that is, submerged “wing” structures, that are coupled to the hull of the marine vessel by struts. When the marine vessel is traveling at a high speed, the water flow over the foils creates a lifting force that causes the vessel to rise in the water. Sufficiently high speeds can produce enough lift to raise the hull of the marine vessel entirely out of the water. Cruising with the marine vessel's hull out of the water is known as foiling, and it produces a fast, efficient, and comfortable ride to the occupants of the marine vessel. This is because a foilborne vessel is not subject to drag effects of water on the hull, nor the pitch and roll motions caused by waves acting on the hull. Accordingly, hydrofoil marine vessels have been embraced for a variety of applications, including racing, ferrying, and military transport.
Various modes of propulsion (e.g., sails, waterjets, outboard motors) may be utilized by the hydrofoil marine vessel to achieve the speed required to operate in a foiling mode. However, once the vessel is foilborne, obstructions in the water such as floating logs, rocks, and sandbars can pose a significant risk to continued operation in foiling mode and to the vessel in general. The present inventor has recognized that if a hydrofoil marine vessel suffers a sudden loss of lift due to a failure of the foil system (e.g., a structural failure due to the foils striking an object in the water, a communications failure between the foils and a foil controller), the hydrodynamic resistance encountered by the hull as it rapidly re-enters the water can be extremely dangerous due to the great discrepancy in density between air and water (i.e., air is approximately 800 times less dense than water at sea level). The present disclosure provides embodiments of a hydrofoil powerboat vessel having a propulsion system, and a control system and method therefor, that detects a loss of lift event and mitigates the danger to the vessel and its occupants by increasing the thrust generated by the propulsion system upon detection of the loss of lift event in order to safely control the vessel deceleration.
The marine vessel 10 is further shown to include hydrofoiling structural components that extend from a lower surface of the hull 12. These structural components include struts 18 and foils 20. As shown in
In some implementations, one or more propulsors (not shown), such as one or more propellers or impellers, driven by the first and second propulsion devices 27, 28 are incorporated into the hydrofoiling structural components positioned at the aft end 16 of the marine vessel 10. In other implementations, the marine vessel 10 utilizes conventional outboard motors such that the propulsors driven by the first and second propulsion devices 27, 28 are positioned separate from the hydrofoiling structural components. The propulsors create a thrust force in the body of water that propels the marine vessel 10 while the vessel 10 is operating in both foiling and non-foiling modes.
The specific details of the geometry of the struts 18 and foils 20 (e.g., hydrofoil shape, strut length) are not particularly limited. For example, the foils 20 may have any known hydrofoil shape (e.g., a National Advisory Committee for Aeronautics (NACA) profile) that results in fluid moving more quickly over an upper surface of the foil 20 as compared with a lower surface of the foil 20. This discrepancy in speeds of fluid moving over the surfaces of the foils 20 is due in part to viscous effects that lead to the formation of vortices at the trailing edges of the foils 20. As the speed along a streamline of fluid traveling over the upper surfaces of the foils 20 increases, the pressure drops, leading to a lower ambient pressure above the foils 20, and the resulting net force on the foils 20 is a lifting force that raises the hull 12 of the marine vessel (see
In various implementations, certain aspects of the foil structure including the struts 18 and foils 20 may be actuatable between various configurations and positions to achieve optimal foiling conditions. For example, in some implementations, the foil structure may include an actuating mechanism that varies the angle of attack of one or more of the foils 20 to generate desired lift. The angle of attack refers to the angle of the foil relative to the incoming fluid flow. In general, hydrofoils require smaller angles of attack (e.g., 150 or less) as compared with airfoils. In other implementations, the struts 18 may be retractable or foldable, such that the foils 20 are only positioned beneath the hull 12 as depicted in
As described above, the first and second marine propulsion devices, 27 and 28, are steerable about their respective axes, 21 and 22. Signals provided by the propulsion controller 116 allow the first and second marine propulsion devices 27, 28 to be independently rotated about their respective steering axes in order to coordinate the movement of the marine vessel 10 in response to operator commands. In an exemplary implementation, any or all of the propulsion devices 27 and 28, throttle lever 50, GPS devices 101 and 102, IMU 106, propulsion controller 116, and foil structure controller 120 may be communicatively coupled using a controller area network (CAN) bus. In an exemplary implementation, data messages are transmitted to any node or device on a CAN bus and do not contain addresses of either the transmitting node or the intended receiving node. Instead, the content of the message is labeled by an identifier that is unique throughout the network. All other nodes on the network receive the message and each performs an acceptance test on the identifier to determine if the message, and thus its content, is relevant to that particular node. If the message is relevant, it will be processed. Otherwise, the message is ignored. The unique identifier also may determine the priority of the message. In one example, the lower the numerical identifier, the higher the priority of the message. The higher priority message will gain access to the CAN bus as if it were the only message being transmitted at that time. Lower priority messages are automatically retransmitted in the next bus cycle, or in a subsequent bus cycle if there are still other higher priority messages waiting to be sent.
Prior to time 414, the velocity of the hydrofoil marine vessel 10 (shown on plot 400 as the solid line 408) is at a local maximum value, Vmax, as the vessel 10 operates in the foiling mode. Typical velocities of the vessel 10 in foiling mode may range from 10 knots for a smaller vessel to 50 knots or more for larger vessels. At the same time, the percentage of maximum thrust provided by the propulsion system (shown on plot 400 as the dashed line 410), is less than 100%. As described above, due to the reduction in drag on the hull 12 due to its position above the waterline 24, the demand on the propulsion devices 27, 28 is significantly less when operating in foiling mode than the demand that would be experienced if the vessel was operating at the same velocity in non-foiling mode.
At time 414, the hydrofoil marine vessel 10 suffers a loss of lift event. The loss of lift event may be caused by a structural failure of the foil system, including the struts 18 and/or the foils 20. The structural failure may be due to conditions external to the marine vessel 10. For example, the vessel 10 may strike an object in the water (e.g., a log, a rock), or may be operating in insufficiently deep water, causing the struts 18 and/or foils 20 to strike a sandbar and fracture or sustain significant damage. In other examples, the loss of lift event may be due to conditions internal to the marine vessel 10. For example, the foil system may suffer a mechanical failure (e.g., failure of actuators that control the angle of attack of the foils 20) or a communications failure (e.g., interruption of communications between the foil structure controller 120 and actuators that control the angle of attack of the foils 20, interruption of communications between the foil structure controller 120 and angle of attack sensors that sense the positions of the foils 20, interruption of communications between the IMU 106 and the propulsion controller 116) that results in a splashdown event and/or otherwise prevents the vessel 10 from continual operation in foiling mode.
Graph line 408 exemplifies the behavior of a marine vessel following a sudden loss of lift event, where the velocity of the marine vessel 10 (indicated by solid line 408) begins to decelerate very rapidly after the loss of lift event at time 414 until it reaches zero. As described above, due to the discrepancy in the densities of air and water, a sudden interruption in the lifting force that causes the hull 12 of the vessel 10 to drop back below the waterline 24 can be highly dangerous to the marine vessel 10 and its occupants.
However, if the marine vessel 10 is operating according to the disclosed emergency mitigation methods and systems, at time 416, the loss of lift event is detected. As described in further detail below with reference to
At time 420, the thrust output of the propulsion devices 27, 28 indicated by dashed line 410 reaches a maximum representative of a predetermined thrust increase condition, before beginning to decline after time 420. For example, the thrust provided by the propulsion devices 27, 28 may decrease by 5% per second until the velocity of the vessel 10 reaches zero. In some implementations, the maximum thrust output of the propulsion devices 27, 28 at time 420 is 100% of the maximum thrust that could be provided by these devices (e.g., maximum RPM, wide open throttle, or maximum current). In other implementations, the maximum thrust at time 420 provided by the propulsion devices 27, 28 is less than 100% of the possible maximum thrust, but instead may be a lesser value determined based on sensed parameters or control values at the time of detecting the loss of lift event. For example, an increased target output of one or more of the propulsion device(s) 27, 28 may be determined as a multiple of the thrust provided prior to detection of the loss of lift event at time 416 (e.g., 1.5× or 2× the thrust provided during normal foiling mode operation). In other embodiments, the increased target output as represented by the speed of the driveshaft, throttle position, or motor current consumption may be determined as a percentage or multiple of the velocity of the marine vessel 10 at the time of detecting the loss of lift event (i.e., time 416).
At step 504, the propulsion controller 116 detects a loss of lift event. The loss of lift event may be detected using a variety of methods. In some implementations, the propulsion controller 116 detects the loss of lift event responsive to measurements provided by the IMU 106. For example, the propulsion controller 116 may determine that a change in position (e.g., a pitch, roll, or yaw movement) of the vessel 10 as indicated by the IMU 106 exceeding a predetermined threshold is representative of a loss of lift event (e.g., the foil structure striking a log or rock and causing a heave motion of the vessel 10). The propulsion controller 116 may also determine than an impulse acting upon the vessel 10 as indicated by velocity and/or acceleration measurements supplied by the IMU 106 exceeds a predetermined threshold representative of a loss of lift event. The acceleration measurements supplied by the IMU 106 additionally constrain the amount of time in which the propulsion controller 116 can respond to the loss of lift event, as described below.
In further implementations, the loss of lift event may be determined by the propulsion controller 116 based on communications received from the foil structure controller 120. If the foil structure controller 120 transmits a message to the propulsion controller 116 that the actuators utilized to modify the angle of attack of the foils 20 are no longer responding to commands (e.g., because the actuators and/or the foils 20 were damaged in a log strike event), the propulsion controller 116 may determine that a loss of lift event has occurred based on the lack of actuator response. In still further implementations, the propulsion controller 116 may detect a loss of lift event based on operator error (e.g., an extreme change in heading commanded by the operator using the joystick 50) that would tend to result in failure of operation of the marine vessel 10 in the foiling mode.
At step 506, the propulsion controller 116 responds to detection of the loss of lift event by transmitting a high priority request over the CAN bus to the propulsion devices 27, 28 to immediately increase the thrust provided to the vessel 10. As described above, the high priority request over the CAN bus may include transmitting a message with a unique identifier having a low numerical value that is guaranteed to gain access to the bus as if it were the only message being transmitted at that time. In an exemplary implementation, the increase in thrust may be based upon a current velocity of the vessel 10 as measured by the IMU 106. The faster the vessel 10 is traveling in foiling mode, the greater the increase in thrust responsive to a loss of lift event. The increase in thrust provided by the propulsion devices 27, 28 responsive to the high priority request is depicted between time 416 and 420 on
At step 508, process 500 concludes as the propulsion controller 116 decreases the thrust provided by the propulsion devices 27, 28 until the marine vessel 10 reaches a predetermined safe velocity. This is depicted beginning at time 420 on
This written description uses examples to disclose the invention, including the best mode, and to enable any person skilled in the art to make and use the invention. Certain terms have been used for brevity, clarity and understanding. No unnecessary limitations are to be inferred therefrom beyond the requirement of the prior art because such terms are used for descriptive purposes only and are intended to be broadly construed. The patentable scope of the invention is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they have features or structural elements that do not differ from the literal language of the claims, or if they include equivalent features or structural elements with insubstantial differences from the literal languages of the claims.
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