Auto balancing hydrofoil watercraft

Abstract

A motorized hydrofoil watercraft using auto-balancing technology to dynamically balance the watercraft using acceleration in response to pitch changes, and to automatically maintain the watercraft at a desired elevation. The speed of the watercraft can be controlled by shifting of the rider's weight, or by fore-aft translation of the hydrofoil relative to the hull.

Description

FIELD OF THE INVENTION

The present invention relates to motor-powered hydrofoil watercraft and, more specifically, to methods of controlling such watercraft.

BACKGROUND OF THE INVENTION

Current motor-powered personal hydrofoil surfboards in the market require the rider to control the elevation of the board by shifting his or her weight fore and aft, while controlling speed using a handheld remote control. This control method requires the rider to learn the skill of elevation control through a substantial amount of practice, which may be a barrier to adoption for some potential users. It also requires part of the rider's attention to be always directed toward elevation control, which may pose a safety risk, especially for novice users, if the rider is devoting a great deal of attention to elevation control and less attention to the surrounding environment. Failure of the rider to maintain a certain degree of stability in elevation control leads to the board contacting the water at speed (if elevation becomes too low) or to the hydrofoil breaching the water surface and consequently suddenly losing lift (if elevation becomes too high), both of which can cause inconvenience, discomfort, and in some cases hazard.

The handheld remote method of speed control is not optimal because the rider must shift his or her weight to compensate for inertia during acceleration or deceleration and may accidentally over- or undercompensate for a given amount of acceleration, causing the rider's weight to shift unwantedly and thereby causing unintended elevation changes. The rider must also use weight shifts to compensate for pitch changes ensuing from acceleration and deceleration of the watercraft.

SUMMARY OF THE INVENTION

The present invention provides a watercraft device as claimed in claim 1 and claim 9. Preferred features are recited in the dependent claims appended hereto.

The present invention may be embodied as a motorized hydrofoil watercraft using auto-balancing technology to control speed and elevation. Motorized hydrofoil watercrafts have a causal relationship between acceleration and pitch angle that makes them suitable for control by methods commonly used in the field of auto-balancing devices. The motor may be driven to dynamically balance the watercraft in the fore-aft dimension using pitch angle data from a position sensor. Speed can be controlled by the rider shifting weight fore or aft in some embodiments, or by moving the hydrofoil fore or aft relative to the center of gravity of the watercraft in other embodiments.

In preferred embodiments, the watercraft is configured to automatically maintain a set desired elevation of the board or hull above the water surface using data from an elevation sensor. This may be accomplished by adjusting the current desired pitch angle to raise or lower the elevation of the watercraft when it deviates from the set desired elevation. Automatic elevation control combined with pitch-based speed control makes the watercraft easier and more comfortable to operate by eliminating difficulties associated with conventional configuration.

The present invention may be embodied as surfboard-like or boat-like craft, or any other form of motorized hydrofoil watercraft.

These and related objects of the present invention are achieved by use of a hydrofoil watercraft with auto-balancing technology as described herein.

The attainment of the foregoing and related advantages and features of the invention should be more readily apparent to those skilled in the art, after review of the following more detailed description of the invention taken together with the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a perspective view of one embodiment of a hydrofoil watercraft in accordance with the present invention.

FIG. 2 shows a perspective view of another embodiment of a hydrofoil watercraft in accordance with the present invention.

FIG. 3 shows a perspective view of another embodiment of a hydrofoil watercraft in accordance with the present invention.

DETAILED DESCRIPTION

Referring to FIG. 1, a perspective view of a hydrofoil watercraft 10 embodying the present invention is shown. Watercraft 10 comprises a surfboard-like buoyant hull 1 capable of supporting at least one rider, a hydrofoil 4 rigidly mounted on a fuselage 5 that contains a propulsion member 3, and a strut 2 that rigidly connects fuselage 5 to hull 1. A position sensor 6 and a control circuit are included in fuselage 5. In other embodiments the position sensor and control circuit may be located elsewhere, such as in the hull. It is not necessary for the control circuit to be located near the position sensor as is the case in this embodiment.

When watercraft 10 is travelling through water, the lift created by hydrofoil 4 supports hull 1 above the water. Because the overall center of gravity of watercraft 10 is higher than hydrofoil 4 and propulsion member 3, acceleration and deceleration will cause watercraft 10 to undergo changes in pitch angle (i.e., tilting forward or backward). The control circuit uses position data from position sensor 6 to drive propulsion member 3 toward dynamically balancing watercraft 10 such that the pitch angle of hull 1 is maintained at a desired pitch angle (in most cases horizontal) during use. Since hydrofoil 4 does not move relative to the hull 1, hydrofoil 4 will also be maintained at a certain desired angle of attack. A rider supported by hull 1 may control the watercraft speed by shifting his weight fore or aft to affect a pitch change and trigger acceleration or deceleration in response to the pitch change, in a manner similar to that used in self-balancing vehicles on land. The data used to balance the watercraft includes pitch angle and may also include other position data and/or other information about the status of the watercraft. Position sensor 6 may be a gyrosensor combined with an accelerometer or may be any other suitable position sensing method.

A pressure sensor 7 is mounted on the surface of fuselage 5 to monitor the depth of hydrofoil 4 in the water. In other embodiments the pressure sensor may be located elsewhere, such as on the hydrofoil or on the strut. The control circuit can use data from pressure sensor 7 to maintain a preset desired depth of hydrofoil 4, via adjusting the desired pitch angle of watercraft 10 while travelling. For instance, when the depth of hydrofoil 4 is detected by pressure sensor 7 to be deeper than the desired depth, the control circuit can automatically increase the current desired pitch angle to cause watercraft 10 to tilt backward, thus increasing the angle of attack of hydrofoil 4 to ascend to the desired depth. Likewise, when the depth of hydrofoil 4 is detected to be shallower than the desired depth, the desired pitch angle is automatically adjusted to decrease the angle of attack of hydrofoil 4 to descend to the desired depth. The control circuit may have two control loops in effect: one to maintain watercraft 10 balancing at a desired pitch angle based on data from position sensor 6, and one to maintain a desired elevation of watercraft 10 by adjusting the current desired pitch angle based on data from pressure sensor 7.

It is possible to maintain a desired elevation using only a pressure sensor without a position sensor. When the depth of hydrofoil 4 is detected by pressure sensor 7 to be deeper than the desired depth, the control circuit can direct propulsion member 3 to accelerate to cause watercraft 10 to tilt backward, or when the depth of hydrofoil 4 is detected to be shallower than the desired depth, the control circuit can direct propulsion member 3 to decelerate to cause watercraft 10 to tilt forward.

In this embodiment the elevation measurement is provided by a pressure sensor which measures depth underwater, but in other embodiments alternative elevation sensor(s) may be used, for example an ultrasonic sensor may be mounted on the hull to monitor the distance of the bottom of the hull from the water surface below. The ultrasonic sensor may also be mounted on an underwater portion of the watercraft to monitor the water surface from below. Methods of monitoring elevation other than those described here may exist and may be suitable for use in embodiments of the present invention.

The embodiment shown in FIG. 1 has a single hydrofoil, but other embodiments may have two hydrofoils separated by a fore-aft distance and/or a vertical distance to increase lift and stability. The two-foil configuration may be especially advantageous in embodiments where the length of the hydrofoil(s) is limited by design considerations.

Other embodiments may have a hull which is much smaller than that shown in FIG. 1. For instance, the hull may be as small as possible while still having adequate surface area to support the rider's feet. FIG. 3 shows a version of watercraft 10 with a foot supporting member rigidly connected to strut 2 instead of a surfboard-like hull. This embodiment may have foot straps for securing at least one of the rider's feet to the foot supporting member, or may have a leg supporting member with leg straps to secure and support at least one of the rider's legs, or any other means for securing the rider to the watercraft to aid in stability and control.

Referring to FIG. 2, a perspective view of a hydrofoil watercraft 100 embodying the present invention is shown. Watercraft 100 is similar to watercraft 10 described above but has a boat-like hull 101 instead of the surfboard-like hull shown in FIG. 1. Watercraft 100 may include components that are the same as or similar to those in watercraft 10. For example, watercraft 100 includes a position sensor 106, an elevation sensor 107, a hydrofoil 104 rigidly mounted on a fuselage 105 that contains a propulsion member 103, and a strut 102 rigidly connected to fuselage 105. In this embodiment strut 102 is movably connected to hull 101 (instead of rigidly connected as in FIG. 1) so that hull 101 can move forward or backward relative to strut 102. The movement between hull 101 and strut 102 can be controlled by a motor (operated by a rider) or by human power. Unlike watercraft 10 where the speed of the craft is controlled by the rider's fore-aft weight distribution, speed control is achieved in watercraft 100 by moving strut 102, and therefore also hydrofoil 104, fore or aft relative to hull 101. Alternatively, fuselage 105 moving relative to strut 102, or hydrofoil 104 moving relative to fuselage 105, can achieve the desired result of shifting the center of gravity of watercraft 100.

In other embodiments, instead of moving hull 101 relative to strut 102, a weight inside of hull 101 can move relative to hull 101 to shift the watercraft's center of gravity. The watercraft's battery may be used as the weight which is moved.

The same principles of the invention described above can apply to other motorized hydrofoil watercraft of various forms not limited to surfboard-like and boat-like craft. The present invention can also be applied to watercraft without a human rider and operated either remotely or automatically.

While the invention has been described in connection with specific embodiments thereof, it will be understood that it is capable of further modification, and this application is intended to cover any variations, uses, or adaptations of the invention following, in general, the principles of the invention and including such departures from the present disclosure as come within known or customary practice in the art to which the invention pertains and as may be applied to the essential features hereinbefore set forth, and as fall within the scope of the invention and the limits of the appended claims.

Claims

1. A watercraft device comprising: at least one hydrofoil;an above-water member rigidly coupled to the at least one hydrofoil and supported above the water surface by the at least one hydrofoil while the watercraft device is traveling;a propulsion member for propelling the watercraft device;at least one position sensor; anda control circuit that drives the propulsion member toward maintaining a preset angle of attack of the hydrofoil based on data from the position sensor.

2. The watercraft device of claim 1, further comprising an elevation sensor, wherein the set angle of attack is adjusted by the control circuit based on data from the elevation sensor to maintain the above-water member at a set elevation.

3. The device of claim 2, wherein the elevation sensor is a pressure sensor.

4. The device of claim 2, wherein the elevation sensor is an ultrasonic sensor.

5. The device of claim 1, further comprising a strut that connects the hydrofoil and the propulsion member to the above-water member.

6. The device of claim 1, wherein the hydrofoil is movable in the fore-aft direction relative to the center of gravity of the above-water member.

7. The device of claim 1, further comprising a weight which is movable in the fore-aft direction relative to the center of gravity of the above-water member.

8. The device of claim 1, wherein the position sensor includes at least a gyrosensor.

9. A watercraft device comprising: at least one hydrofoil;an above-water member rigidly coupled to the at least one hydrofoil and supported above the water surface by the at least one hydrofoil while the watercraft device is traveling;a propulsion member for propelling the watercraft device;at least one elevation sensor; anda control circuit that drives the propulsion member toward maintaining a preset depth of the hydrofoil based on data from the elevation sensor.

10. The device of claim 9, wherein the elevation sensor is a pressure sensor.

11. The device of claim 9, wherein the elevation sensor is an ultrasonic sensor.

12. The device of claim 9, further comprising a strut that connects the hydrofoil and the propulsion member to the above-water member.

13. The device of claim 9, wherein the position sensor includes at least a gyrosensor.