WO2021191729A1

WO2021191729A1 - Hydrofoil with autopilot configuration

Info

Publication number: WO2021191729A1
Application number: PCT/IB2021/052159
Authority: WO
Inventors: Corentin Francis LEGRIS; Michael RISCHMÜLLER; Aurélien Henry; Baptiste Tripard
Original assignee: Fly 4 All Sa
Priority date: 2020-03-27
Filing date: 2021-03-16
Publication date: 2021-09-30

Abstract

The present invention discloses an autopilot hydrofoil for a watercraft. The autopilot hydrofoil comprises at least a pair of flaps, a computing device comprising a computing component and a sensor assembly in communication with the computing device to detect the motion parameters of the watercraft. Each flap is operatively connected to an actuator via a push rod. The computing component is configured to receive one or more input parameters to control the motion of the hydrofoil and extract references from the input parameters. The computing device further configured to receive one or more motion parameters of the watercraft, and extract references from the motion parameters. The extracted references of the one or more input parameters and one or more motion parameters are compared to generate a command signal to control the pair of flaps according to the one or more input parameters.

Description

HYDROFOIL WITH AUTOPILOT CONFIGURATION

BACKGROUND OF THE INVENTION A. Technical field

[1] The present invention generally relates to a hydrofoil with autopilot configuration. B. Description of related art

[2] In recent years, hydrofoil supported watercraft has been increased steadily. The hydrofoil generally comprises wing-like devices which produce a lifting force when propelled through the water, the lift created by the hydrofoil raises the hull above the surface of the water, thus eliminating the hull's resistance. These performance enhancements have been limited by difficulties associated with the hydrofoil control mechanisms.

[3] Conventional hydrofoil craft utilizes sophisticated control systems including either mechanical or electronic sensing devices to determine the craft’s position over the water and, in turn, to control the angles of incidence of the various foils. These control systems have often included gyros and high-performance autopilots. Such systems are expensive and are not applicable to anything but the very largest hydrofoil craft. With particular regard to sailboats, none of the known hydrofoil systems have combined simplicity in construction with high performance and efficiency as is necessary to provide an ideal foil system. [4] Few existing patent references attempted to address the aforementioned problems are cited in the background as prior art over the presently disclosed subject matter and are explained as follows.

[5] A prior art US3886884 to Donald R Stark, entitled “control system for hydrofoil” discloses a control system for a hydrofoil of the type having forward and aft submerged foils for supporting the craft while foil borne. 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.

[6] Another prior art EP0118737 to Yasuhiro Itoh, entitled “Stabilizing foils for a hydrofoil craft” discloses a hydrofoil, provided on an underwater portion thereof with rolling preventing movable flaps projecting from the hydrofoil approximately at right angles therewith. Each of the movable flaps is turnable about a rod extending in the direction of the projection. Previous designs for hydrofoil craft have not fully addressed all the requirements for a control system that accommodates varying weather, sea, and load conditions.

[7] Therefore, there is a need for a hydrofoil with autopilot configuration that addresses the aforementioned drawbacks.

SUMMARY OF THE INVENTION

[8] The present invention discloses an autopilot hydrofoil for a watercraft. The autopilot hydrofoil comprises at least a pair of flaps, a computing device comprising a computing component and a sensor assembly in communication with the computing device to detect the motion parameters of the watercraft. Each flap is operatively connected to an actuator via a push rod. The computing component is configured to receive one or more input parameters to control the motion of the hydrofoil and extract references from the input parameters. The one or more input parameters includes desired attitude, roll, pitch and height above water.

[9] The computing device is in communication with a user-input device associated with a user to input one or more input parameters. The user-input device is at least one of a personal computer, a smartphone or a mobile phone. The computing device is in communication with one or more cameras disposed on the watercraft. The one or more cameras are configured to capture the movement of the user to extract one or more input parameters. The movement of the user includes the tilt of the user. The tilt of the user is extracted from the movement of the user and sent to the computing device as a desired attitude, roll and pitch, and/or height above water. The sensor assembly comprises accelerometers, gyroscope, barometer and ultrasonic sensor. The hydrofoil further comprises a battery assembly to supply power to the actuator, sensor assembly, computing device and other elements of the hydrofoil.

[10] The computing device further configured to receive one or more motion parameters of the watercraft, and extract references from the motion parameters. The extracted references of the one or more input parameters and one or more motion parameters are compared to generate a command signal to control the pair of flaps according to the one or more input parameters. The computing device is further configured to transmit the command signal to the actuator. The actuator is configured to control movement of each flap to correct height, roll or angular rates to reach the input parameters inputted by the user.

[11] Other objects, features and advantages of the present invention will become apparent from the following detailed description. It should be understood, however, that the detailed description and the specific examples, while indicating specific embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description.

BRIEF DESCRIPTION OF DRAWINGS

[12] FIG. 1 exemplarily illustrates a side view of a hydrofoil with autopilot configuration, according to an embodiment of the present invention.

[13] FIG. 2 exemplarily illustrates an environment of the watercraft having the hydrofoil with autopilot configuration, according to an embodiment of the present invention. [14] FIG. 3 exemplarily illustrates a hydrofoil with autopilot configuration, according to an embodiment of the present invention.

[15] FIG. 4 exemplarily illustrates a front view of the hydrofoil with autopilot configuration, according to an embodiment of the present invention.

[16] FIG. 5 exemplarily illustrates a push rod of the hydrofoil, according to an embodiment of the present invention.

[17] FIG. 6 exemplarily illustrates a housing of the hydrofoil comprising computing device, sensor assembly and electrical actuators, according to an embodiment of the present invention.

[18] FIG. 7 exemplarily illustrates the housing of the hydrofoil having a battery assembly, according to an embodiment of the present invention.

[19] FIG. 8 exemplarily illustrates a front view of the housing, according to an embodiment of the present invention.

[20] FIG. 9 exemplarily illustrates a front view of the housing without a cover member, according to an embodiment of the present invention.

[21] FIG. 10 exemplarily illustrates a side view of the hydrofoil having a propeller assembly, according to an embodiment of the present invention.

[22] FIG. 11 exemplarily illustrates a side view of a strut, according to an embodiment of the present invention.

[23] FIG. 12 exemplarily illustrates a cross sectional view of the hydrofoil, according to another embodiment of the present invention. [24] FIG. 13 exemplarily illustrates a cross sectional view of the housing including computing device, according to one embodiment of the present invention.

[25] FIG. 14 exemplarily illustrates a cross sectional view of the housing including computing device, according to another embodiment of the present invention.

[26] FIG. 15 exemplarily illustrates a sensor assembly of the hydrofoil, according to one embodiment of the present invention. [27] FIG. 16exemplarily illustrates a watercraft having one or more hydrofoils, according to an embodiment of the present invention.

[28] FIG. 17 exemplarily illustrates a fuselage of the hydrofoil without an enclosing showing components therein, according to an embodiment of the present invention.

[29] FIG. 18 exemplarily illustrates a hydrofoil mounted with at least one camera, according to an embodiment of the present invention.

DETAILED DESCRIPTION OF EMBODIMENTS [30] A description of embodiments of the present invention will now be given with reference to the figures. It is expected that the present invention may be embodied in other specific forms without departing from its spirit or essential characteristics. The described embodiments are to be considered in all respects only as illustrative and not restrictive. The scope of the invention is, therefore, indicated by the appended claims rather than by the foregoing description. All changes that come within the meaning and range of equivalency of the claims are to be embraced within their scope. [31] Referring to FIG.l, the present invention discloses a hydrofoil 100 having autopilot configuration. In one embodiment, the hydrofoil 100 comprises a rear wing 104 and a front wing 102, the hydrofoil 100 is attached to a hull by a strut/mast 106 to serve as a mdder. The front wing 102 comprises a pair of flaps (108, 110) that are pivotally mounted on the foil and are individually controlled to move upward and downward independently of each other, as shown in FIG. 4. The rear wing 104 is configured to act as a stabilizer.

[32] The hydrofoil 100 includes one or more actuators (240a, 240b) including a first actuator 240a and a second actuator 240b. Each actuator (240a, 240b) is secured on a housing 112, shown in FIG. 4, of the hydrofoil 100 and operably connected to the respective flap (108, 110). Each flap (108, 110) is operatively connected to the respective actuator (240a, 240b) via a push rod 120, shown in FIG. 5. Each push rod 120 having a lower end connected to the respective flap (108, 110) and an upper end connected to the respective actuator (240a, 240b).

[33] FIG. 2 illustrates an environment 200 of the watercraft 240 having the hydrofoil 100 with autopilot configuration the hydrofoil 100 further comprises an onboard computing device 118, to automate the operation of the hydrofoil 100. The computing device 118 is disposed within the housing 112. The computing device 118 comprises a computing component configured to automate the operation of the hydrofoil 100. The computing device 118 is configured to receive one or more input parameters for controlling/automating the operation of the hydrofoil 100, thereby, controlling the motion of a watercraft 240. In one embodiment, the one or more input parameters includes desired attitude, roll and pitch, or height above water. In one embodiment, the details of the computing device 118 in accordance with the present invention is disclosed. The computing device 118 may include a processing unit, a peripheral/video interface, a removable memory interface, a network interface, and a user input interface. The computing device 118 may also include a memory. A system bus may be used to couple the aforementioned components and any other included components.

[34] The system memory may include computer storage media in the form of volatile and/or nonvolatile memory such as read only memory (ROM) and random-access memory (RAM). A basic input/output system (BIOS), containing the basic routines that help to transfer information between elements within the computing device 118, such as during start-up, is typically stored in ROM. RAM typically contains data and/or program modules that are immediately accessible to and/or presently being operated by the processing unit.

[35] The RAM may include an operating system, program data and the computing component. The computing component and any other application programs stored in RAM may be described in the general context of computer-executable instructions, such as program modules, being executed by a computer. Generally, program modules include routines, programs, objects, components, data structures, etc. that perform particular tasks or implement particular abstract data types. Moreover, those skilled in the art will appreciate that the invention may be practiced with other computer system configurations, including multiprocessor systems, microprocessor-based or programmable consumer electronics, minicomputers, mainframe computers, and the like.

[36] The computing device 118 may also include other removable/non-removable, volatile/nonvolatile computer storage media. A hard disk drive may be provided that reads from or writes to non-removable, nonvolatile magnetic media, a magnetic disk drive that reads from or writes to a removable, nonvolatile magnetic disk, and an optical disk drive that reads from or writes to a removable, nonvolatile optical disk such as a CD ROM or other optical media. Other removable/non-removable, volatile/nonvolatile computer storage media that can be used in the exemplary operating environment include, but are not limited to, magnetic tape cassettes, flash memory cards, digital versatile disks, digital video tape, solid state RAM, solid state ROM, and the like. The hard disk drive is typically connected to the system bus through a non-removable memory interface. The magnetic disk drive and optical disk drive are typically connected to the system bus by a removable memory interface.

[37] A user may enter commands and information through the user input interface module 238 using input devices/user-input devices such as a smartphone or a mobile device. Other input devices may include a keyboard and pointing device, commonly referred to as a mouse, trackball or touch pad. Yet other input devices may include a microphone, satellite dish, scanner, one or more cameras or the like. Yet other input devices include sensor assembly comprising one or more sensors 236 disposed at the hydrofoil 100 or watercraft 240. These and other input devices are often connected to the processing unit through the user input interface that is coupled to the system bus, but may be connected by other interface and bus structures, such as a parallel port or a universal serial bus (USB). A monitor or other type of display device and other peripherals may also be connected to the system bus via an interface, such as the peripheral interface.

[38] The user is enabled to input one or more input parameters to control the motion of the hydrofoil 100 via the mobile device. In another embodiment, body movements or other body information of the user are captured as one or more input parameters to the computing device 118. One or more sensors 236 are utilized to track the movement of various parts of the body, which is used as input parameters by the computing device 118 to control the hydrofoil 100. In one embodiment, the sensors 236 include, but not limited to, accelerometer and gyroscope. In another embodiment, one or more cameras 234 are utilized to track the movement of various parts of the body of the user, which is used as input parameters by the computing device 118 to control the hydrofoil 100. One or more cameras 234 include, but not limited to, 3D (3-Dimensional) camera, and stereo camera. The tilt of the user is extracted from the image of the user and sent to the computing device 118 as the desired attitude, roll and pitch, and/or height above water.

[39] The computing device 118 is merely an example of a suitable environment for the system of the invention and is not intended to suggest any limitation as to the scope of use or functionality of the invention. Neither should the computing device 118 be interpreted as having any dependency or requirement relating to any one or combination of components illustrated.

[40] The computing device 118 in embodiments of the present invention may operate in a networked environment using logical connections to communicate with networked components. Logical connections for networking may include a local area network (LAN) or a wide area network (WAN), but may also include other networks. When used in a LAN networking environment, the system may be connected to the LAN through the network interface or adapter. When used in a WAN networking environment, the computing device 118 typically includes a modem, a network interface, or other means for establishing communications to a WAN, such as the Internet. The modem, which may be internal or external, may be connected to the system bus via the user input interface or other appropriate mechanism.

[41] Network generally represents one or more interconnected networks, over which the user devices and server can communicate with each other. Network may include packet-based wide area networks (such as the Internet), local area networks (LAN), private networks, wireless networks, satellite networks, cellular networks, paging networks, and the like. A person skilled in the art will recognize that network may also be a combination of more than one type of network. For example, network may be a combination of a LAN and the Internet. In addition, network may be implemented as a wired network, or a wireless network or a combination thereof.

[42] Referring to FIG. 3 and FIG. 4, a side view and a front view of the hydrofoil 100 having the autopilot configuration is illustrated, respectively. The actuators (240a, 240b) are linear actuators including electric motors. However, one will appreciate that other suitable actuators may be employed to move the flaps (108, 110), including hydraulic and pneumatic motors. Preferably the actuators (240a, 240b) are watertight or water resistant, and more preferably waterproof. The actuators (240a, 240b) are configured to pivot the flaps (108, 110) about their respective pivot axis and position the flaps (108, 110) in different positions. One will also appreciate that manual actuators or positioners may be utilized to secure the flaps (108, 110) in the desired position.

[43] Referring to FIG.5, a lower end of the push rod 120 is connected to flap (108, 110) (shown in FIG. 3) via a linkage or any other means. The push rod 120 is substantially rectangular in cross section and extends upwardly through the strut 106, having an upper end connected the respective actuator (240a, 240b). The push rod 120 is configured to reciprocate along its longitudinal axis.

[44] FIG. 6 exemplarily illustrates the housing 112 of the hydrofoil 100 comprising the computing device 118, sensor assembly comprising the one or more sensors 236 and actuators (240a, 240b), according to an embodiment of the present invention. The sensor assembly is in communication with the computing device 118. In one embodiment, the one or more sensors 236 include, but not limited to, accelerometers, gyroscope, barometer, ultrasonic sensor. The accelerometer is configured to collect acceleration data, the gyroscope is configured to collect data for maintaining and measuring the angular velocity, the barometer is configured to measure air pressure and/or water pressure data and the ultrasonic sensor is configured to collect data to determine distance of watercraft with respect to objects or waves ahead.

[45] FIG. 7 exemplarily illustrates the housing 112 of the hydrofoil 100 having a battery assembly 115, according to an embodiment of the present invention. The battery assembly 114 includes a plurality of battery modules to supply power to the actuator (240a, 240b), the sensor assembly, the computing device 118, and any other element of the hydrofoil 100 that may require power. A power converter 116 is disposed to distribute power to the elements of the hydrofoil 100, shown in FIG. 9. Referring to FIG. 8, a front view of the housing 112 is disclosed, according to an embodiment of the present invention. The housing 112 encompasses the battery assembly 115, actuators (240a, 240b) and the computing device 118. A cover member 122 is disposed to seal an opening of the housing 112 in a waterproof manner. FIG. 9 exemplarily illustrates a front view of the housing 112 without the cover member 122, according to an embodiment of the present invention.

[46] In one embodiment, the operation of the hydrofoil 100 supported watercraft is disclosed. During cruising of the watercraft, the user would be on the board. The hydrofoil 100 of the watercraft would be submerged in the water. The wind or the force created by the waves move the watercraft. The user inputs one or more input parameters via the input device. In one embodiment, the input device is a smartphone having a mobile application in communication with the computing device 118. [47] In another embodiment, the user inputs one or more input parameters through the body movement of the user. One or more cameras 234 disposed on the watercraft is configured to detect the orientation of the user and sends the data to the computing device 118. The computing component is configured to extract one or more input parameters from the orientation of the user. The roll and pitch extracted from the orientation of the user is used as height, roll and angular rate settings. Further, the computing device 118 is configured to extract references from the input parameters.

[48] The computing device 118 is configured to estimate the motion parameters including the current attitude of the watercraft using the computing component and data from the sensor assembly including accelerometers, barometer, ultrasonic sensor and gyroscopes. The computing component executing on the onboard computer would algorithmically fuse the sensor data to extract the best estimate of Euler angles/height above water. The computing component is configured to compare the references from the input parameters and motion parameters and generate a com and signal for the pair of flaps (108, 110) including the left and right flaps (108, 110).

[49] An electrical command signal is sent from the onboard computing device 118 to the actuators (240a, 240b). The actuators (240a, 240b) would pull the two flaps (108, 110) up and down through the push rod 120, mixing the height and roll/angular rate command. The movement of flaps (108, 110) would generate a moment and a force that would correct the height and or roll/angular rates to reach the desired references selected by the user. The user could decide to maintain a zero roll at all time or a zero angular rate around the roll axis. Through the difference between the zero roll or the zero angular rate around the roll gyroscope axis, a command signal would be generated to move the flaps (108, 110) to counter the current movement of the watercraft. For instance, if the watercraft is falling on its right side with a positive roll, the right flap 108 of the front wing 102 would be pulled down, and the left flap 110 would be pulled up.

[50] With the described actuation, the lift of the right flap 108 would increase whereas the lift of the left flap 110 would decrease generating a moment counteracting the original movement of the watercraft, and would thus stabilize the watercraft at the desired attitude or desired angular rate. The configuration of the autopilot hydrofoil 100 allows the user to take off at much lower speed compared to normal foil or conventional foil. The autopilot hydrofoil 100 includes at least two mode of operations, including, but not limited to, a beginner mode and a non-beginner mode. The beginner mode is configured to allow a full control on zero roll desired and constant height above water with high reactivity, and therefore providing low maneuverability on the roll axis. A non-beginner mode would be a zero angular rate desired control on the roll axis, allowing the user to have some/limited maneuverability on this axis. [51] The height of the watercraft would be also controlled according to the user settings. In most cases, the height reference would be compared against the current estimated height. The estimated height is an algorithmic fusion of the sensed height above water using, for instance, an ultrasonic board, fused with the vertical acceleration sensed by the accelerometer and the onboard barometer. The computing device 118 would generate a command pulling the flaps (108, 110) up if the height is above the reference height above water. When pulling the flaps (108, 110) upward, the lift would decrease and the watercraft would go down. The control parameters such as the sensitivity of the height or roll axis controllers, could be set via an application component in the input device wirelessly connected to the onboard computer. The application component could be a smartphone application or a desktop application on the input device. The input device could be a personal computer, a smartphone, or a mobile phone.

[52] Referring to FIG. 10, the hydrofoil 100 comprises a propeller assembly including at least one propeller 124. In one embodiment, the propeller assembly is integrated as a fuselage. In another embodiment, the propeller assembly is clamped to the strut 106, at a portion above the fuselage. In one embodiment, the at least one propeller 124 could be a classical propeller, a ducted propeller, a water jet turbine or any other type of propeller. Referring to FIG. 11, the top portion of the strut 106 comprises a step structure or a staircase structure 126 to provide more space for the vertical movement of push rod 120. The step structure 126 in the mast 106 is clamped to the rear portion of the housing 112 to ensure maximum rigidity.

[53] Referring to FIG. 12 exemplarily illustrates a cross sectional view of the hydrofoil 100, according to another embodiment of the present invention. Referring to FIG. 13, the housing 112 comprises O-ring, sealant joint 128 to be compressed between the forward side of the mast 106 and the housing 112 to ensure maximum waterproofing of the push rod 120 transition between inside and outside of the housing 112. The positioning of the component of the hydrofoil 100 is designed to minimize the height of positioning of the housing 112 to reduce hydrodynamic drag during the take-off phase (board still contacting the water). Further, servo motors are positioned at a side portion of the housing 112. The housing 112 encases servo motors, sensors 236, power board, battery assembly 114 and mounting plate for the hydrofoil 100 to be mounted on the watercraft.

[54] FIG. 14 exemplarily illustrates a cross sectional view of the housing 112, according to another embodiment of the present invention. The design of the hydrofoil 100 enables better space optimization, effective weight distribution, robustness and effectively addresses leak issues. One or more holes are provided to guide the push rod 120 and to avoid the push rod 120 to bend under mechanical effort by maintaining it straight along the mast 106 (shown in FIG. 11). The oblong shape also allows necessary degree of freedom in the forward direction to avoid over constraints when moving the flaps (108, 110) up and down due to the conversion of the rotational movement of the flaps (108, 110) to a translational movement of the push rod 120.

[55] The positioning of the holes of the push rod 120 and screws holes are optimized to comply to the following requirement including: minimum amount of material thickness required in the mast 106 profile to ensure manufacturability and strength; and minimum mast 106 profile overall thickness to minimized hydrodynamic drag. FIG. 13 and FIG. 14 shows the optimized component arrangement of the housing 112 to minimize hydrodynamic drag and optimized assembly rigidity and robustness which relates directly to the hydrofoil 100 performance. The holes of push rod 120 are disposed at forward portion as much as possible because the front wing 102 needs to be forward as much as possible for better balancing of the hydrofoil 100. The large hollow inside the mast 106 profile is necessary to allow cable pathway for sensors 236 and power supply for motor in case of provision of additional electric motor.

[56] In one embodiment, the mast 106 connects a lower portion of the hydrofoil 100 to an upper portion of the hydrofoil 100. During operation of the hydrofoil 100, the lower portion of the hydrofoil 100 remains below the water and the upper portion remains above the water level. In one embodiment, the housing 112 is disposed at the upper portion of the hydrofoil 100. The housing 112 includes an onboard computer/ computing device 118, servomotor, remote control receiver and sensors 236. The computing device 118 is configured to minimize drag and reduce the take- off speed of the hydrofoil watercraft. The computing device 118 is configured to adjust the angle of the flaps (108, 110) with regards to the relative speed of the water flow and the hydrofoil 100 to minimize the drag and take-off speed. In one embodiment, one or more sensors 236 are utilized to estimate the relative speed of the water flow and the hydrofoil 100. The sensors 236 include static pressure sensor and dynamic pressure sensor. In one embodiment, one or more sensors 236 are disposed at a point where static pressure is observed and at a point where total pressure is observed.

[57] In another embodiment, the computing device 100 is configured to provide asymmetric control and fall detection of hydrofoil watercraft. The computing device 100 is configured to implement asymmetric correction on the roll axis to avoid having the roll control perturbing the user or rider. When the angular speed is in the direction of the water (phi gets bigger), a flap (108, 110) command is sent that is the opposite of p defined as the roll angular rate. When phi gets smaller, a correction to the flap (108, 110) is not sent, in order to avoid having the roll control going against the rider’s will to go back to the zero attitude. [58] The overall command law is the following: if (Phi * p < 0.0) then roll_axis_command=0 Else roll_axis _command = PID(phi_refphi,p)

PID function refers to proportional, integral derivative control which is a standard control technique that mixes different variables from an element that rider or user needs to control.

[59] In yet another embodiment, the height control stability is improved by measuring water height in advance. Referring to FIG. 15, the variable height of the waves is measured using one or more ultrasonic sensors (130a, 130b). The control/computing device 118 (shown in FIG. 2) will react exactly at that moment, and its reaction on the actual board’s height above water will have some delay. To improve the efficiency of the height control, another ultrasonic sensor 130b pointing at 45degrees forward, in order to anticipate the incoming waves, and reduces the delay in height control. In one embodiment, at least one ultrasonic sensor 130a is disposed at the front portion of the hydrofoil 100 that faces forward direction and at least one ultrasonic sensor 130b is disposed at the front portion of the hydrofoil 100 that faces downward direction.

Zaverage_k = Zaverage_k-1 + Gain * UltrasonicProjected_{j-ront k} — UltrasonicProjected_{down fe})

[60] UltrasonicProjected_{d wn fc}is the height measure of the ultrasonic sensor 130b projected onto the earth vertical axis at the instant k, and UltrasonicProjectedf_{ront fc}is the height measure of the front ultrasonic sensor projected onto the vertical axis. The average water height is estimated and converge to it with a tunable time (Adapting the Gain), and therefore control the foil 100 on the average height of the water anticipating for the waves. [61] Pressure bias is estimated by checking the difference between front ultrasonic sensor (130a,

130b) and pressure sensor 132. The pressure sensor 132 has an inherent bias that changes the depth estimation depending on the weather conditions. Therefore, the height control cannot work with a correction of this bias. Thus, the bundle of the ultrasonic sensor (130a, 130b) pointing downwards together with the pressure sensor 132 is used to estimate this depth bias. The typical recursive estimation is the following

Bias_k = Bias_k-1 + Gain * ( Depth_k — Ultrasonic _k)

[62] The Gain can be arbitrarily chosen to choose the convergence time of the bias. Before the ultrasonic measure can be used, it has to be filtered beforehand, because the ultrasonic measure has some outliers. In one embodiment, a median filter, or an outlier rejection filter is used for this purpose. The bias recursive equation will be only calculated when the ultrasonic measure will be considered as valid. [63] During operation of the hydrofoil 100, at certain speed and certain position of the hydrofoil 100 and the mast 106, the pressure field around the wind gets perturbed. Therefore, one or more pressure sensors 132 are disposed along the mast 106 to discretize the mast height. When cruising, one or more pressure sensors 132 remains under water and one or more pressure sensors 132 remains above the water level, which is used to deduct the position of the hydrofoil 100 by interpolation of the positions between the pressure in the air that has the highest pressure value (the closest to the water) and the velocity estimated by the sensor fusion (especially by using the estimated vz velocity integrated from the IMU and corrected with the GPS velocity). As a result, the height measure will be more robust to the pressure issues of a fast cruising hydrofoil.

[64] In yet another embodiment, a global positioning system is used to control the height and for estimation of height. Further, a Kalman filter and data of the GPS system, velocity, ultrasonic sensor (130a, 130b) and the depth senor for improving the height estimation and the height control. In yet another embodiment, the computing device 118 allows the user to control the mast 106 height programmatically through the computing component. Therefore, the rider or the user can select or configure the height of the mast 106 and avoid several hydrofoils for several practices.

[65] In yet another embodiment, a geolocation sensor is coupled to the computing device 118 to track, stream and emit the location of the watercraft at any point in time. The computing device 118 allows the user to emit an emergency location signal. Further, a geofence can be configured to avoid the rider to go outside a predefined polygon in space. If the watercraft goes outside a predefined polygon, the computing device 118 is configured to either steer it back to the inside of the polygon or change the power of the powertrain to either stop it or reduce speed.

Referring to FIG. 17, in one embodiment, the hydrofoil 100 includes an optimized powertrain design to minimize the space taken by the group battery, speed controller and propeller/turbine and improves the stability of the hydrofoil 100 by placing the weight of the battery pack 114 underwater. In another embodiment, the powertrain is directly disposed at the fuselage to improve the overall stability for a rider and reduces the size of the powertrain. The hydrofoil 100 includes mechanical stmcture, electrical actuators (240a, 240b), various sensors 236 (FIG. 2), an onboard computer or computing device and a control software. The mechanical structure includes a rear wing 104 also referred as stabilizer, a front wing 102 with flaps (108, 110), and a fuselage that hosts an electric battery pack 114, an electronic speed controller (ESC) 136, a waterjet turbine, or a propeller 124, and electric motor 134. [67] In one embodiment, one or more hydrofoils 100 of the present invention could be used to control complex or heavy watercraft 1500 structure. Referring to FIG. 16, the watercraft 1500 has a configuration with at least three hydrofoils/foils 100, hereinafter referred as a front foil and a pair of rear foil. The front foil will mainly control the height of the watercraft by pulling up or down both of its flaps (108, 110), whereas the rear foils will pull both their flaps (108, 110) up or down to control the overall roll of the watercraft 1500. The rear foils have two propulsion units, being either a motor with a propeller (as shown on the drawing) or two waterjets. The yaw (heading) axis is controlled via a mix of a moving vertical surface along the mast or via the roll control of the watercraft, plus a com anded thrust difference between the two motors. All the foils 100 are communicating with each other through a bus, in order to distribute the commands and use all the set of sensors 236 as redundant sensors.

[68] During cruising, the user using the water craft would be standing on the board, with the hydrofoil 100 submerged into the water. The force created by the powertrain move the watercraft or watercraft system. On a classical electric foil, the board on top of the mast usually contains the battery assembly, the remote-control receiver and the electronic speed controller (ESC) 136. Due to its position inside the board, therefore above the water, the ESC 136 has to be cooled down by a water pump, water cooling system, and power cable with significant diameters has to go through the mast down to the electric motor that is submerged into water.

[69] Referring to FIG. 17, however, in the present invention, the fuselage is essentially a tube that contains the three components, electric motor 134, battery 114 and ESC 136. The effect it has on the foil 100 is double. First, with this configuration, the only cables that have to be sent to the board above the water are tiny command cables so the remote control can send the command to the ESC 136. A complex cooling system is also not necessary with this system because the ESC 136 is always underwater and cooled directly by conduction of the tube. The size of power cables is also reduced. The second effect is that compared to a classical system where the battery pack 114 is on the board where a significant part of the weight is on the board and above the wing, the biggest part of the weight of the system is contained in the fuselage between the front wind and the stabilizator. Therefore, instead of increasing the inverted pendulum effect (a battery pack for an electric foil usually weights around 30Kg), the stability is increased by placing the battery pack 114 in the fuselage. The current attitude will be sensed by an algorithmic fusion of the accelerometers and gyroscopes. A command law is then computed into the onboard computing device 118 in order to adapt the roll axis of the system according to the user predefined settings. The user can decide to maintain a zero roll at all time or a zero angular rate around the roll axis.

[70] Through the difference between the zero roll or the zero angular rate around the roll gyroscope axis, a command will be generated to move the flaps (108, 110) to counter the current movement of the boards. For instance, if the board is falling on its right side with a positive roll, the right flap 108 of the front wing 102 will be pulled down, and the left flap 110 will be pulled up. With the described actuation, the lift of the right flap 108 will increase whereas the lift of the left flap 110 will decrease generating a moment counteracting the original movement of the board, and will thus stabilize the board at the desired attitude or desired angular rate.

[71] The height of the watercraft will be also controlled according to the user settings. In most cases, the height reference will be compared against the current estimated height. The estimated height is an algorithmic fusion of the sensed height above water using, for instance ultrasonic sensors (130a, 130b), fused with the vertical acceleration sensed by the accelerometer and the onboard barometer. The computing device 114 will generate a command pulling the flaps (108,

110) up if the height is above the reference height above water. When pulling the flaps (108,

110) upward, the lift will decrease and the watercraft will go down. The control parameters such as the sensitivity of the height or roll axis controllers, can be set via a separate software wirelessly connected to the onboard computing device 118. This software can be a smartphone application, or a desktop application on a personal computer.

[72] Referring to FIG. 18, at least one camera 302 is mounted to the hydrofoil 100 in such that the camera faces downwards direction towards the water. The at least one camera 302 in communication with the computing device 118. The at least one camera 302 is configured to estimate the velocity of the foil 100 relatively to the flow of water using a computer vision algorithm. In one embodiment, the computer vision algorithm is an optical flow algorithm. The optical flow algorithm is configured to estimate the direction and magnitude in pixel per sec of the apparent movement captured by the camera 302. After being reprojected in the world frame, the velocity can be scaled from pixel per seconds to meters per seconds using the height above water estimate, and the information could be fused with other sensors including data such as distance ‘z’ from ultrasonic sensor 130a to have the best estimate of foil velocity relative to the flow of water. The flow algorithm also provides redundancy in the sensing of velocity. Further, the amplitude of the control commands could be adapted depending on the estimate of velocity. [73] The foregoing description comprise illustrative embodiments of the present invention.

Flaving thus described exemplary embodiments of the present invention, it should be noted by those skilled in the art that the within disclosures are exemplary only, and that various other alternatives, adaptations, and modifications may be made within the scope of the present invention. Merely listing or numbering the steps of a method in a certain order does not constitute any limitation on the order of the steps of that method. Many modifications and other embodiments of the invention will come to mind to one skilled in the art to which this invention pertains having the benefit of the teachings presented in the foregoing descriptions. Although specific terms may be employed herein, they are used only in generic and descriptive sense and not for purposes of limitation. Accordingly, the present invention is not limited to the specific embodiments illustrated herein. While the above is a complete description of the preferred embodiments of the invention, various alternatives, modifications, and equivalents may be used. Therefore, the above description and the examples should not be taken as limiting the scope of the invention, which is defined by the appended claims.

Claims

1. An autopilot hydrofoil for a watercraft, comprising: at least a pair of flaps, each flap operatively connected to an actuator via a push rod, a computing device comprising a computing component, and a sensor assembly in communication with the computing device configured to detect one or more motion parameters of the watercraft, wherein the computing component is configured to: receive one or more input parameters to control the motion of the hydrofoil, wherein the one or more input parameters includes desired attitude, roll and pitch, or height above water, extract references from the input parameters, receive one or more motion parameters of the watercraft, extract references from the motion parameters, compare the extracted references of the one or more input parameters and one or more motion parameter and generate a command signal to control the pair of flaps according to the one or more input parameters, and transmit the com and signal to the actuator, wherein the actuator is configured to control movement of each flap to correct height, roll or angular rates to reach the input parameters inputted by the user.

2. The autopilot hydrofoil of claim 1, wherein the computing device is in communication with a user-input device associated with a user to input one or more input parameters.

3. The autopilot hydrofoil of claim 1, wherein the computing device is in communication with a global positioning system and one or more cameras disposed on the watercraft, and the one or more cameras are configured to capture a movement of the user to extract one or more input parameters.

4. The autopilot hydrofoil of claim 3, further comprises at least one camera in communication with the computing device configured to estimate the velocity of the hydrofoil relatively to the flow of water using a computer vision algorithm.

5. The autopilot hydrofoil of claim 3, wherein the movement of the user includes tilt of the user, and the tilt of the user is extracted from the movement of the user and sent to the computing device as a desired attitude, roll and pitch.

6. The autopilot hydrofoil of claim 1, wherein the computing device is disposed within a housing of the hydrofoil.

7. The autopilot hydrofoil of claim 1, wherein the sensor assembly comprises accelerometers, gyroscope, barometer, one or more pressure sensors and one or more ultrasonic sensors, the one or more pressure sensors are arranged along a length of a strut at regular intervals, the one or more pressure sensors includes a dynamic pressure sensor and a static pressure sensor, the one or more ultrasonic sensors includes at least one ultrasonic sensor arranged to face forward direction and at least one ultrasonic sensor arranged to face downward direction.

8. The autopilot hydrofoil of claim 1, further comprises a battery assembly to supply power to the actuator, sensor assembly and computing device.

9. The autopilot hydrofoil of claim 1, is configured to allow the user to take off at much lower speed compared to conventional foil.

10. The autopilot hydrofoil of claim 1, is configured to at least two mode of operation including a beginner mode and a non-beginner mode, wherein the beginner mode is configured to allow a full control on zero roll desired and constant height above water with high reactivity, and therefore low maneuverability on the roll axis, and wherein the non-beginner mode is configured to allow a zero angular rate desired control on the roll axis, allowing the rider to have some maneuverability on this axis.

11. The autopilot hydrofoil of claim 1, wherein the push rod having a lower end connected to the flaps and an upper end connected to the respective actuator.

12. The autopilot hydrofoil of claim 1, wherein the push rod is substantially rectangular in configuration configured to reciprocate long the longitudinal axis.

13. The autopilot hydrofoil of claim 1, further comprises a power converter in communication with battery assembly configured to distribute power to one or more elements of the hydrofoil.

14. The autopilot hydrofoil of claim 1, further comprises a propeller assembly comprising at least one propeller clamped to the strut, at a portion above a fuselage.

15. The autopilot hydrofoil of claim 14, wherein the propeller assembly is integrated as a fuselage.

16. The autopilot hydrofoil of claim 7, wherein the top potion of the strut comprises a step structure to provide more space for the vertical movement of push rod, and the step structure of the strut is clamped to a rear portion of the housing to ensure maximum rigidity.

17. The autopilot hydrofoil of claim 16, wherein the housing comprises O-ring, sealant joint to be compressed between the forward side of the strut and the housing to ensure maximum waterproofing of the push rod transition between inside and outside of the housing.

18. The autopilot hydrofoil of claim 17, further comprises one or more holes to guide the push rod and to avoid the push rod to bend under mechanical effort.

19. The autopilot hydrofoil of claim 17, wherein the strut comprises a substantially large hollow to allow cable pathway for sensors and power supply for motor in case of provision of additional electric motor.

20. The autopilot hydrofoil of claim 19, wherein the configuration of strut allows necessary degree of freedom in the forward direction to avoid over constraints when moving the flaps up and down due to the conversion of the rotational movement of the flaps to a translational movement of the push rod.