The present invention relates to methods of steering aquatic vessels, for example to methods of steering fishing boats, pleasure boats, high speed boats and similar. Moreover, the present invention also concerns apparatus for steering aquatic vessels. Furthermore, the invention relates to software executable on computing hardware for implementing steering control pursuant to the method of the invention.
Powered aquatic vessels are well known. Such vessels typically include at least one hull having one or more engines accommodated therein. A mechanical output of each engine is coupled to one or more propellers which are submerged in operation for providing propulsion through water. Moreover, a vessel includes a steering arrangement which involves at least one of pivoting one or more rudders or pivoting one or more propeller assemblies to control a direction of travel and, in the case of stern drive or outboard engines, pivoting the engines to control the direction of travel.
Referring to
The boat 10 further includes a control unit 70 coupled in communication with servo actuators associated with the drives 30, 50 for controlling their orientation angles α1, α2, their power output, and also a direction of rotation of their one or more propellers, namely forward or reverse. The servo actuators (not shown) are optionally implemented using hydraulic actuators or electric motors with associated angular and/or position sensors. Coupling from the control unit 70 is optionally implemented by at least one of a mechanical connection, electric connection, fiber optical connection, and/or wireless communication. The control unit 70 is also coupled for communication with a steering console 80 by which a user is able to steer and control a speed of travel of the boat 10. The steering console 80 includes a rotatable steering wheel 90. The steering console 80 also includes a lever arrangement 100 comprising one or more levers for controlling a direction of rotation of propellers associated with the first and second engines 30, 50 respectively, and also average power output delivered from the engines 30, 50 to their associated propellers. If a fishing boat, and particularly, a deep-sea fishing boat, the boat 10 conventionally has a length on the order to 12 to 15 meters, often referred to by convention as a “40 foot” boat.
Operation of the boat 10 will now be described. When traveling in a forward direction, the lever arrangement 100 is controlled by the user for specifying whether the engines are coupled via the transmission or drive 30, 50 to their associated propellers in a forward gear or a reverse gear. For propelling the boat 10 in a forward direction, the drives 30, 50 associated with the engines are both set in forward gear. Moreover, for propelling the boat 10 in a reverse direction, the drives 30, 50 associated with the engines are both set in reverse gear. The lever arrangement 100 also enables the user to specify a general combined output power of the two engines to their associated propellers. Rotation of the steering wheel 90 correspondingly controls the angles α1, α2 which are substantially mutually similar in operation; in other words, the drives 30, 50 are operable to angularly pivot in synchronism so that substantially α1=α2 as illustrated in
The inventors have appreciated that the boat 10 illustrated schematically in plan view in
Performance of the boat 10 is can be improved by increasing power output of the engines, by increasing responsiveness of the aforementioned servo actuators, and by increasing a maximum range for the steering angles α1, α2. However, such modifications potentially compromise a design of the hull 20, add additional weight to the boat 10, and potentially increase the cost of manufacturing the boat 10.
Thus, the present invention is concerned with addressing a problem that contemporary aquatic vessels are not as maneuverable as desired, especially for specialized operations such a hunting big fish.
An object of the present invention is to provide an improve method of steering aquatic vessels.
According to a first aspect of the invention, there is provided a method of steering an aquatic vessel including at least one hull and at least one engine couplable to rotationally drive a plurality of mutually spatially separate corresponding propeller assemblies for providing thrusts to propel the vessel through water in operation,
wherein directions of the thrusts developed by the plurality of the propeller assemblies are angularly adjustable (α1, α2) relative to the at least one hull, and
wherein the vessel is further provided with a control unit for receiving user commands (S1, S2) and for sending corresponding signals for controlling powers (P1, P2) coupled from the at least one engine to the propeller assemblies, the method including steps of:
The invention is of advantage in that coordinated control of both the angles (α1, α2) and the difference in power (ΔP) coupled to the propeller assemblies is capable of providing an enhanced degree of aquatic vessel maneuverability.
The method may include a step of controlling said angles (α1, α2), that is, angular orientations, of the plurality of mutually spatially separated propeller assemblies so as to develop their thrusts along corresponding directions which are mutually substantially parallel. For example, as described later, when the vessel includes two mutually similar angularly pivotally mounted propeller assemblies, the two assemblies pivot together with substantially similar associated pivot angles, for example as illustrated in
Optionally, as a further refinement to improve steering control, the method includes a step of applying an angular correction when controlling the angles (α1, α2), the angular correction being a function of the angles (α1, α2) and a speed of the vessel in water in operation. Such correction is also known generally as “Ackerman” correction.
According to an embodiment of the method, the function relating the difference in power (ΔP) with the angles (α1, α2) of the thrusts of the propeller assemblies relative to the at least one hull includes at least one of: a linear function, a polynomial function, a logarithmic function, an exponential function. Such functions fundamentally affect a steering “feel” of the vessel when in operation. Such “feel” can be very important to vessel control when struggling to capture a large fish; poor control of the vessel during a struggle can potentially result in the fish pulling the vessel into a dangerous orientation with a risk that the vessel takes on water and sinks.
Optionally, the function relating the difference in power (ΔP) with the angles (α1, α2) of thrusts developed by the propeller assemblies relative to the at least one hull is user selectable via the control unit. The user is thus able to vary the steering “feel” of the vessel to cope with various different vessel steering scenarios.
According to one embodiment of the invention, at least one of the plurality of propeller assemblies includes a mutually counter-rotating pair of propellers. Such counter-rotating propellers are of benefit in that they are potentially capable of developing more thrust for a given propeller diameter before limitations of cavitation are reached.
Optionally, at least one of the propeller assemblies is pivotally mounted in respect of the at least one hull. The at least one propeller assembly may be pivotally servo-actuated in response to signals provided from the control unit.
According to another aspect of the invention, the method comprises the step of generating the first and second user commands in response to user manipulation of a pair of mutually independently adjustable controls.
According to yet another aspect of the invention, the pair of mutually adjustable controls are implemented as two independently adjustable levers, wherein the difference in power (ΔP) is determined as a function of relative positions of the levers, and the angles (α1, α2) also corresponding determined as a function of the relative positions of the levers. Such control using, for example two levers, is in stark contrast with a contemporary trend of using steering wheels in a manner utilized in road vehicles.
According to the invention, the method may include a step of generating the first and second user commands in response to user manipulation of a single control having at least two mutually independently adjustable degrees of freedom.
The single control may be in the form of a joystick. Advantageously, the method is implemented in a “fly-by-wire” manner wherein the joystick is coupled electrically to the control unit so that substantially negligible user physical effort is required to steer the vessel.
Optionally, the method includes a step of implementing the control unit by at least one of computer hardware operable to execute a software product, mechanical logic, and hydraulic logic.
Optionally, in the method, the control unit is user switchable between a conventional mode of steering the vessel and a method pursuant to the present invention as defined in the accompanying claims.
Optionally, the method is adapted for use when fishing for large fish, for example, swordfish or tuna.
According to another aspect of the invention, there is provided an aquatic vessel comprising at least one hull, at least one engine couplable to rotationally drive a plurality of mutually spatially separate corresponding propeller assemblies for providing thrusts to propel the vessel through water in operation, wherein directions of the thrusts developed by the plurality of the propeller assemblies are angularly adjustable (α1, α2) relative to the at least one hull, a control unit for receiving user commands (S1, S2) and for sending corresponding signals for controlling powers (P1, P2) coupled from the at least one engine to the propeller assemblies, wherein the control unit is configured to receive at least first and second user commands (S1, S2), wherein the control unit is operable to determine a difference in power (ΔP) in response to receiving the at least first and second user commands (S1, S2) to be coupled from the at least one engine to the plurality of propeller assemblies as a function of the first and second user commands (S1, S2), wherein the control unit is operable to control coupling of power (P1, P2) to the plurality of propeller assemblies in response to the at least first and second user commands (S1, S2) so that the plurality of propeller assemblies develop a difference in thrust which is a function of the difference in power (ΔP); and wherein the control unit is operable to adjust angles (α1, α2) of the directions of thrusts as a function of the difference in power (ΔP) so as to assist the difference in power (ΔP) coupled to the plurality of propeller assemblies to enhance maneuverability of the vessel in operation.
Optionally, in a vessel according to the invention, the control unit is operable to control the angles (α1, α2) of the plurality of mutually spatially separated propeller assemblies so as to develop their thrusts along directions which are mutually substantially parallel.
Optionally, in a vessel according to the invention, the control unit is operable to apply an angular correction when controlling the angles (α1, α2), the angular correction being a function of the angles (α1, α2) and a speed of the vessel in water in operation.
According to the invention, the function relating the difference in power (ΔP) with the angles (α1, α2) of the thrusts of the propeller assemblies relative to the at least one hull includes at least one of a linear function, a polynomial function, a logarithmic function, and an exponential function.
Optionally, in a vessel according to the invention, the function relating the difference in power (ΔP) with the angles (α1, α2) of thrusts developed by the propeller assemblies relative to the at least one hull is user selectable via the control unit.
According to another aspect of the invention, at least one of the plurality of propeller assemblies may include a mutually counter-rotating pair of propellers.
Alternatively, at least one of the propeller assemblies is pivotally mounted with respect to the at least one hull. Alternatively, the at least one of the propeller assemblies is pivotally servo-actuated in response to signals provided from the control unit.
Optionally, the first and second user commands are generated in response to user manipulation of a pair of mutually independently adjustable controls.
Optionally, the pair of mutually adjustable controls are implemented as two independently adjustable levers, wherein the difference in power (ΔP) is determined as a function of relative spatial positions of the levers, and the angles (α1, α2) are also correspondingly determined as a function of the relative spatial positions of the levers.
Alternatively, the first and second user commands are generated in response to user manipulation of a single control having at least two mutually independently adjustable degrees of freedom. According to yet another alternative, the single control is in the form of a joystick.
Optionally, the control unit is implemented by at least one of computer hardware operable to execute a software product, mechanical logic, and hydraulic logic.
Optionally, to accommodate ergonomics and preferences of different users, the control unit is user switchable between a conventional mode of steering the vessel and a mode of steering wherein the angles (α1, α2) and the difference in power (ΔP) are controlled in combination.
Advantageously, the vessel is adapted for use when fishing for large fish, for example, swordfish and tuna.
According to another aspect of the invention, there is provided a software product stored on a data carrier or conveyed via a signal, said software product being executable on computing hardware for implementing a method according to the invention.
It will be appreciated that features of the invention may be combined without departing from the scope of the invention as defined by the accompanying claims.
The present invention will be better understood by reference to the detailed description in conjunction with the accompanying drawings, in which:
a, 3b, and 3c are graphs illustrating relationships between a relative power difference specified for the two engines of the boat of
a and 4b illustrate exemplary implementations of user controls for the boat of
In the accompanying drawings, an underlined number is employed to represent an item over which the underlined number is positioned or an item to which the underlined number is adjacent. A non-underlined number relates to an item identified by a line linking the non-underlined number to the item. When a number is non-underlined and accompanied by an associated arrow, the non-underlined number is used to identify a general item at which the arrow is pointing.
In overview, the present invention is concerned with methods of steering aquatic vessels to provide them with enhanced maneuverability. The methods concern both angularly orienting a plurality of propeller assemblies in combination with adjusting a difference in the relative engine outputs to provide enhanced vessel maneuverability. Such methods diverge from contemporary methods of steering boats which increasingly mimic a steering function of a road vehicle with steering wheel. The methods of the present invention are mutually distinguished by a manner in which relative power to the plurality of engines is varied in response to angle orientations of the engines and their propeller assemblies, and vice versa.
Referring to
The boat 200 in
The first and second levers 220, 230 may be configured to be mutually independently controlled by the user. For example, the first lever 220 can be pulled back towards the user in operation to place the first drive 30 in reverse gear, while the second lever 230 can be pushed forwards away from the user in operation to place the second drive 50 into forward gear. Moreover, the first and second levers 220, 230 can be user manipulated to demand mutually different levels of power output from the first and second engines 30, 50 respectively. Such a degree of control is not possible with the steering console 80 and the software product of the control unit 70 implemented pursuant to
The pivot angles α1, α2 as shown in
α1=α2+F(α1, VB) Eq. 1
wherein
F=“Ackerman” function providing an angular correction which is, in practice, often at least an order of magnitude smaller than the angles α1, α2; and
VB=velocity of the boat 200 in water.
The velocity VB is a temporal function of an average power output for the first and second engines at any given instance of time; it is a temporal function on account of issues of acceleration, namely the boat 200 takes time to attain a given velocity in response to applying a power demand to the first and second engines. The function F is to a first approximation a simple linear function. However, it is optionally a higher order polynomial function when precise refinement of performance of the boat 200 is desired.
When the first and second levers 220, 230 are implemented in a mutually similar manner, a difference in relative positions S1, S2 of the levers 220, 230 respectively, namely how far they are pushed or pulled in respect of the user, determines in operation a difference in power ΔP delivered by the first and second engines, respectively.
In other words, the position SI controls a power P1 provided by the first engine to its propeller assembly, the power P1 having a positive value when the propeller assembly of the first engine is coupled in forward gear, and the power P1 having a negative value when the propeller assembly of the first engine is coupled in reverse gear. Moreover, the position S2 controls a power P2 provided by the second engine to its propeller assembly, the power P2 having a positive value when the propeller assembly of the second engine is coupled in forward gear, and the power P2 having a negative value when the propeller assembly of the second engine is coupled in reverse gear. The difference in power ΔP is equal to a difference between the power values P2 and P1.
Equation 2 (Eq. 2) describes such a relationship:
ΔP=G(S2−S1) Eq. 2
wherein, G is a function relating the difference in the relative positions of the first and second levers 220, 230 and a difference in power output ΔP provided by the engines to their propellers. The function G is also a temporal function because the engines are not capable of responding instantaneously to changes in position of the levers 220, 230. The function G is preferably substantially a linear function. The power values P1, P2 delivered from the engines respectively are advantageously approximately proportional in magnitude to the displacement S1, S2 of the levers 220, 230 from their center unbiased positions. Alternatively, the function G is a more complex polynomial function, for example a quadratic or cubic function, or may be a more complex polynomial function that at least approximates a logarithmic- or an exponential-type function. The function G is advantageously implemented at least in part in the software product executable in the computing hardware of the control unit 70.
The present invention is very significantly distinguished from the boat 10 of
α1=H1(ΔP) Eq. 3a
α2=H2(ΔP) Eq. 3b
wherein H1 and H2 are functions relating the angles α1, α2 (see
In operation, when the angles α1, α2 are both positive as illustrated in
The functions H1 and H2 are substantially similar so that the engines of the boat 200 pivot in synchronism in a mutually similar direction as illustrated in
The functions H1, H2 are substantially linear functions as illustrated in
According to another aspect, a plurality of scaling factors for the functions H1 and H2 are user selectable at the steering console 80.
Alternatively, for obtaining special steering characteristics, the functions H1 and H2 are non-linear functions as depicted in
The ease with which the user is able to steer the boat 200 is of importance from an ergonomic viewpoint. A fishing boat is typically provided with equipment, for example a boom with winch at a stern region of the boat 200. When attempting to land a fish, a first person may be stationed at the stern region to operate the fish-catching equipment while a pilot is stationed at the steering console 80 to control movement of the boat 200. The pilot needs to respond quickly to support activities of the first person. It is thus highly desirable that controls of the steering console 80 are as ergonomically easy and convenient to operate as possible. Thus, as an alternative to the aforesaid two levers 220, 230, joystick-type controls can be optionally employed at the steering console 80 as illustrated in
Referring to
An end knob 410 at a distal end of the joystick 400 as illustrated is user-rotatable as denoted by an arrow 420. Rotation of the knob 410 is used to control the difference in power ΔP. Rotation of the knob 410 is spring biased so that the knob 410 returns to a central rotational position corresponding to substantially zero difference in power ΔP when the user does not apply any rotational force thereto. When a relatively larger rotation is applied to the knob 410, it can, for example in an extreme case, result in one of the drives 30, 50 being engaged in forward gear and another of the drives 30, 50 being engaged in reverse gear to provide the boat 200 with an impressively small turning circle in operation.
The joystick control illustrated in
Referring next to
It will be appreciated that the boat 200 can be provided with a steering wheel in a manner akin to
Alternatively, one or more of the drives 30, 50 may be provided with a rudder assembly if required. The rudder assembly is beneficially steerable in its angle relative to its associated drive 30, 50.
The aforementioned “Ackerman” type correction as defined by Equation 1 (Eq. 1) is concerned with a relatively small angular correction to account for a relative difference in water velocity passing by propellers of the drives 30, 50 when performing tight turns, especially at relatively higher speeds. The “Ackerman” correction involves, when a plurality of drives are used (for example the boat 200 has first and second drives 30, 50), pivoting an engine nearest an inside of a tight turn slightly more than an engine furthest from the inside of the tight turn. For example, when the boat 200 performs a tight turn to starboard, the pivot angle α2 of the second drive 50 is rendered slightly greater than the pivot angle α1 of the first drive 30 when an “Ackerman” type correction is applied. As mentioned earlier, use of an “Ackerman” type correction in combination with implementing the present invention is optional.
Although the present invention has been described in the foregoing in respect of the boat 200, it will be appreciated that the present invention is not limited to use in such a configuration and can be adapted for use with other configurations of boats, for example for boats including more than two engines. Moreover, although the boat 200 is described as utilizing dual counter rotating propellers for its drives 30, 50 pursuant to aforesaid International Application No. PCT/SE2004/00206 (WO 2004/074089), the present invention may be used with other propeller configurations, for example single propeller arrangements and triple propeller arrangements. Although implementation of the invention is described in the foregoing in respect of the control unit 70 including computing hardware implemented to execute a software product, it will be appreciated that the control unit 70 can be implemented in dedicated electronic hardware and even using mechanical logic and/or hydraulic logic hardware.
In
Optionally, the boat 200 can be implemented to include a single engine coupled via several variable gearboxes to a plurality of propeller assemblies, wherein each propeller assembly is angularly pivotable in a manner as illustrated in
Modifications to embodiments of the invention described in the foregoing are thus possible without departing from the scope of the invention as defined by the accompanying claims.
Expressions such as “including”, “comprising”, “incorporating”, “consisting of”, “have”, “is” used to describe and claim the present invention are intended to be construed in a non-exclusive manner, namely allowing for items, components or elements not explicitly described also to be present. Reference to the singular is also to be construed to relate to the plural.
Numerals included within parentheses in the accompanying claims are intended to assist understanding of the claims and should not be construed in any way to limit subject matter claimed by these claims.
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