U.S. patent application number 09/811013 was filed with the patent office on 2001-08-02 for streering and thrust control system for waterjet boats background of the invention.
This patent application is currently assigned to The Talaria Company, LLC, a Delaware corporation. Invention is credited to Fadeley, Kenton D., McKenney, Shepard W., Serrao, Thomas M..
Application Number | 20010010987 09/811013 |
Document ID | / |
Family ID | 22518106 |
Filed Date | 2001-08-02 |
United States Patent
Application |
20010010987 |
Kind Code |
A1 |
Fadeley, Kenton D. ; et
al. |
August 2, 2001 |
Streering and thrust control system for waterjet boats background
of the invention
Abstract
A waterjet-driven boat has a reversing bucket for controlling
forward/reverse thrust and a rotatable nozzle for controlling
sideward forces. A bucket position sensor is connected to the
reversing bucket, and the bucket is controlled using the output of
the position sensor to enable the bucket to be automatically moved
to a neutral thrust position. Similarly, a nozzle position sensor
is connected to the nozzle, and the nozzle is controlled using the
output of the nozzle position sensor so that the nozzle may be
automatically returned to a zero sideward force position. A
joystick with two axes of motion may be used to control both the
bucket and the nozzle. The joystick has built-in centering forces
that automatically return it to a neutral position, causing both
the bucket and nozzle to return to their neutral positions.
Inventors: |
Fadeley, Kenton D.;
(Solomons, MD) ; McKenney, Shepard W.; (Dravden,
MD) ; Serrao, Thomas M.; (Orrington, ME) |
Correspondence
Address: |
G. ROGER LEE
Fish & Richardson P.C.
225 Franklin Street
Boston
MA
02110-2804
US
|
Assignee: |
The Talaria Company, LLC, a
Delaware corporation
|
Family ID: |
22518106 |
Appl. No.: |
09/811013 |
Filed: |
March 16, 2001 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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09811013 |
Mar 16, 2001 |
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09146596 |
Sep 3, 1998 |
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6234100 |
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Current U.S.
Class: |
440/40 |
Current CPC
Class: |
B63H 11/11 20130101;
B63H 25/02 20130101; B63H 25/42 20130101 |
Class at
Publication: |
440/40 |
International
Class: |
B63H 011/107 |
Claims
What is claimed is:
1. A boat of the type driven by a waterjet, the boat comprising a
waterjet drive assembly, the assembly including a nozzle directing
a flow of water generally along the longitudinal axis of the boat,
the nozzle being capable of rotation about a generally vertical
axis to provide left and right sideward forces on the boat, and a
reversing bucket for reversing the direction of a variable amount
of the flow of water emerging from the nozzle, the reversing bucket
being adjustable from any of a plurality of forward thrust
positions in which enough water remains unaffected by the reversing
bucket that a net forward thrust is maintained, to a neutral thrust
position in which a substantial fraction of the flow of water is
reversed so that the net thrust of the water reversed and the water
not reversed is approximately zero, to any of a plurality of
reverse thrust positions in which enough water is reversed that a
net reverse thrust is maintained; a bucket position sensor
connected to the reversing bucket to sense the position of the
reversing bucket; a bucket drive mechanism connected to the
reversing bucket to move the reversing bucket between the forward
thrust, neutral thrust, and reverse thrust positions an electrical
control circuit for controlling the drive mechanism in response to
the bucket position sensor so that the reversing bucket can be
automatically moved to the neutral thrust position from a forward
thrust position or from a reverse thrust position.
2. The boat of claim 1 further comprising a stick control member
connected electrically to the electrical control circuit, the stick
control member having a neutral position, at least one forward
position, and at least one reverse position, and the electrical
circuit and position sensor being configured so that when the stick
control member is placed in the neutral position the drive
mechanism moves the reversing bucket to the neutral thrust
position.
3. The boat of claim 2 wherein the stick control member has a
centering force that returns the stick to the neutral position when
released by the operator.
4. The boat of claim 2 or 3 further comprising a nozzle drive
mechanism connected to the nozzle and electrically controlled by
the electrical control circuit, wherein the stick control member is
configured to rotate about a generally vertical axis, and wherein
the electrical control circuitry and nozzle drive mechanism are
configured so that rotation of the stick produces rotation of the
nozzle and sideward forces on the boat.
5. The boat of claim 4 further comprising a nozzle position sensor
providing an electrical signal representative of the angular
position of the nozzle.
6. The boat of claim 4 wherein the stick control member has a
centering torque that returns the stick to a zero rotation position
when released by the operator.
7. The boat of claim 6 wherein the waterjet drive is positioned and
the nozzle drive and electrical control circuitry configured so
that rotation of the stick control member produces a rotation of
the boat in the same rotational direction.
8. The boat of claim 2 wherein the boat further comprises a
bowthruster, wherein the stick control member is configured td move
to the left and right of the neutral position, and wherein the
bowthruster and electrical control circuitry are configured so that
leftward movement of the stick produces a leftward movement of the
bow of the boat and rightward movement of the stick produces
rightward movement of the bow.
9. The boat of claim 2 wherein the boat further comprises a nozzle
drive mechanism connected to the nozzle and electrically controlled
by the electrical control circuit, the stick control member is
configured to rotate about a vertical axis, the electrical control
circuitry and nozzle drive mechanism are configured so that
rotation of the stick produces rotation of the nozzle and sideward
forces on the boat, the boat further comprises a bowthruster, the
stick control member is configured to move to the left and right of
the neutral position, and the bowthruster and electrical control
circuitry are configured so that leftward movement of the stick
produces a leftward movement of the bow of the boat and rightward
movement of the stick produces rightward movement of the bow.
10. The boat of claim 9 wherein the boat is small (i.e., 75 feet or
under in length).
11. The boat of claim 2 wherein the bucket position sensor, stick
control member, and electrical control circuit are configured to
provide at least two modes of operation, a first mode in which a
follow-up relationship exists between forward/aft movement of the
stick control member and up/down movement of the reversing bucket,
and a second mode in which a non-follow-up relationship exists
between forward/aft movement of the stick control member and
up/down movement of the reversing bucket.
12. The boat of claim 11 wherein the boat further comprises a
nozzle drive mechanism connected to the nozzle and electrically
controlled by the electrical control circuit, wherein the stick
control member is configured to rotate about a generally vertical
axis, and wherein the electrical control circuitry and nozzle drive
mechanism are configured so that rotation of the stick produces
rotation of the nozzle and sideward forces on the boat, and a
nozzle position sensor providing an electrical signal
representative of the angular position of the nozzle, and wherein
the nozzle position sensor, stick control member, and electrical
control circuit are configured to provide a follow-up relationship
between the rotation of the stick control member and rotation of
the nozzle.
13. The boat of claim 11 wherein the electrical circuitry is
configured to provide both a docking mode and a power steer mode of
operation, wherein in the docking mode of operation, the bucket
position sensor, nozzle position sensor, and stick control member
are configured so that both bucket position control and nozzle
position control have a follow-up relationship to the respective
movements of the stick control member, and wherein in the power
steer mode of operation, the bucket position sensor, nozzle
position sensor, and stick control member are configured so that
bucket position control is non-follow-up and nozzle position
control is follow-up.
14. The boat of claim 13 wherein in the power steer mode of
operation, the electrical circuitry and stick control member are
configured so that rotational movement of the stick member produces
less rotation of the nozzle than in the docking mode.
15. The boat of claim 13 further comprising a trim adjustment
control that permits the operator to adjust an offset between
nozzle position and stick rotation.
16. The boat of claim 2 further comprising hydraulic control
components, including a hydraulic cylinder and hydraulic valve, for
carrying out movement of the reversing bucket in response to
movements of the stick control member.
17. The boat of claim 16 wherein the hydraulic control components
are configured to provide two speeds of movement of the hydraulic
cylinder, a high speed movement for use when the cylinder is more
than a predetermined distance away from the position prescribed by
the electrical circuitry, and a low speed movement for use when the
cylinder is less than the predetermined distance.
18. A boat of the type driven by a waterjet, the boat comprising a
waterjet drive assembly, the assembly including a nozzle directing
a flow of water generally along the longitudinal axis of the boat,
the nozzle being capable of rotation about a generally vertical
axis to provide left and right sideward forces on the boat, and a
reversing bucket for reversing the direction of a variable amount
of the flow of water emerging from the nozzle, the reversing bucket
being adjustable from any of a plurality of forward thrust
positions in which enough water remains unaffected by the reversing
bucket that a net forward thrust is maintained, to a neutral thrust
position in which a substantial fraction of the flow of water is
reversed so that the net thrust of the water reversed and the water
not reversed is approximately zero, to any of a plurality of
reverse thrust positions in which enough water is reversed that a
net reverse thrust is maintained; a bucket drive mechanism
connected to the reversing bucket to move the reversing bucket
between the forward thrust, neutral thrust, and reverse thrust
positions; a nozzle drive mechanism connected to the nozzle for
rotating the nozzle to vary the left and right sideward forces on
the boat; a stick control system in which a first axes of movement
corresponds to movement of the bucket, and a second axis movement
corresponds to movement of the nozzle; and an electrical control
circuit configured to control the bucket drive mechanism in
response to movement of the stick along the first axis, and to
control the nozzle drive mechanism in response to movement of the
stick along the second axis.
Description
BACKGROUND OF THE INVENTION
[0001] The invention relates to steering and thrust control systems
for waterjet driven boats.
[0002] With a waterjet drive, seawater is drawn in through the
bottom of the boat and ejected in a stream out the back. The
reaction to this movement of water is the propulsive force that
moves the boat. Near the back of the stream is a nozzle, which
serves two functions. It accelerates the stream by reducing its
diameter, and it can be turned from side to side to deflect the
exiting stream to apply a component of side force on the aft part
of the boat. The nozzle is to a jet what a rudder is to a boat
equipped with conventional propellers. Both are typically connected
to a steering wheel.
[0003] The aftmost portion of the jet, just behind the nozzle, is a
device called a reversing bucket. Its function is to allow the
operator to reverse some or all of the stream in order to stop or
back up the boat. In normal underway operation the bucket is
elevated above the stream and has no effect. When reduced forward
thrust is desired the bucket can be lowered into the stream,
forcing a portion of the flow through curved channels until it
exits in a forward and slightly downward direction. When roughly
half the stream is still streaming aft below the bucket and half is
being reversed to a more forward direction (the neutral bucket
position), an approximate balance point can be reached that results
in approximately no forward or aft thrust on the boat. If the
bucket is lowered to the full down position, nearly all the thrust
is reversed and the boat should begin moving in reverse. The
particular design of some reverse buckets (e.g., Hamilton
waterjets), and the way the bucket interacts with the nozzle,
permits a net thrust in any direction in the plane of the water's
surface. Side to side force is adjusted by nozzle position, and
forward or aft force by bucket position.
[0004] A waterjet is either engaged and pumping water or disengaged
and not pumping water. It does not ordinarily have a forward and
reverse in the same manner as a conventional propeller. A
transmission with reverse gear can be provided as a means of
allowing the engine to run without engaging the jet and to allow
for backflushing that results from reversing the drive shaft to the
jet to clear an obstruction that may have been drawn against the
jet inlet. Actual reverse thrust is accomplished with the jet
engaged in the forward direction and the bucket lowered, similar in
concept to the reversing arrangement on aviation jet engines.
[0005] Waterjet drives have numerous advantages, e.g., low draft,
reduced noise, improved high-speed maneuverability. But they can
make a boat difficult to control at slow speeds in tight quarters
(e.g., when docking). The reason for this is that, heretofore,
there has been no simple way to achieve zero thrust or zero side
force. In a conventionally powered boat, zero thrust and zero side
force are easily achieved, simply by putting the transmission into
neutral, thereby bringing the propeller to rest. But with a
waterjet, the only way to achieve zero thrust is to move the bucket
to a position at which the net of the forward and reverse portions
of the jet is balanced. That position can only be chosen
approximately. It takes considerable training and experience for an
operator to acquire a sense of what the waterjet drive is doing, to
allow successful slow speed operation.
[0006] Waterjet drives also behave differently in reverse from
propeller driven craft. Because the flow of water through the jet
is always in one direction, deflection of the stream results in the
same sideward force regardless of whether the boat is moving
forward or in reverse. This is in contrast to a conventional
rudder, whose effect on the stern of a boat is reversed depending
on the direction of travel through the water. This difference in
steering in reverse presents difficulties for new operators, who
anticipate that steering direction will change when the boat is
backing up.
[0007] To control movement of the bow of a boat, some boats are
equipped with bowthrusters. Such a thruster is often installed in a
tube that runs from side to side at the bow below the waterline. In
the middle of this tube is a propeller that can thrust either way
by reversing rotation. In smaller boats, this propeller is usually
driven by an electric motor. The combination of waterjet and
bowthruster can give a boat extraordinary maneuverability. Movement
in any direction in the plane of the water's surface is possible,
even directly sideways. But, unfortunately, the operator is
typically required to skillfully coordinate different controls
simultaneously to take full advantage of this maneuverability.
E.g., a foot pedal or left/right deflection of a hand-operated
lever may be used to control the bowthruster, a steering wheel, to
control the rear nozzle, and a throttle lever, to control
speed.
[0008] Some very large waterjet driven ships have solved the zero
thrust difficulty by controlling the waterjet with an inertial
control system that senses applied thrust (e.g., using
accelerometers), and adjusts the waterjet bucket position until a
desired thrust level is achieved. When the operator desires a zero
thrust level, the control system adjusts the bucket position until
the inertial sensors detect zero applied thrust. This solution is
too expensive for small boats (i.e., boats 75 feet or less in
length).
SUMMARY OF THE INVENTION
[0009] We have discovered an improved method for controlling a
waterjet drive that overcomes prior difficulties with low-speed
handling of boats with waterjet drives. The invention has numerous
advantages. It allows a relatively unskilled operator of a jet boat
to quickly master low-speed control of the boat. In preferred
embodiments, control of reversing bucket, nozzle, and bowthruster
are combined in a single joystick in a manner that is surprisingly
easy for an unskilled operator to master. By having the joystick
return to a neutral position corresponding to balanced, neutral
fore/aft thrust (and preferably also neutral port/starboard nozzle
thrust), it is possible for the operator to reliably put the boat
in neutral, something not readily possible in conventional waterjet
boats. This control arrangement also overcomes the problem that
waterjet drives tend to behave differently in reverse than
conventional propeller driven craft.
[0010] In a first aspect, the invention features providing a bucket
position sensor connected to the reversing bucket of a waterjet
drive, and controlling the bucket in response to an output of the
position sensor to enable the bucket to be automatically moved to a
neutral thrust position.
[0011] One or more of the following features may be incorporated in
preferred embodiments of the invention:
[0012] A joystick may be configured so that when the joystick is
placed in its neutral position the drive mechanism automatically
moves the reversing bucket to the neutral thrust position.
[0013] A centering force can be provided in the joystick so that
when released by the operator, the joystick returns to its neutral
position and the thrust is returned to neutral.
[0014] The joystick can be configured so that rotation (or twist)
of the joystick about a generally vertical axis controls rotation
of the waterjet nozzle about its axis.
[0015] A nozzle position sensor may be connected to the nozzle, and
provide control circuitry with a measurement of the position of the
waterjet nozzle.
[0016] The joystick may have a centering torque that returns the
stick to a zero rotation position when released by the operator.
The control circuitry may be configured with the nozzle position
sensor so that releasing the joystick and allowing it to return to
the zero rotation position automatically causes the nozzle to
return to a zero sideward force position.
[0017] The automatic zeroing of sideward force can be combined with
the automatic zeroing of forward/reverse thrust, so that when the
operator releases the joystick all propulsion forces on the boat
are brought to zero.
[0018] A bowthruster can be controlled by left/right movement of
the same joystick, so that leftward movement of the joystick
produces a leftward movement of the bow of the boat and rightward
movement of the joystick produces rightward movement of the
bow.
[0019] The bucket position sensor, joystick, and control circuitry
may be configured to provide at least two modes of operation, a
first mode in which a follow-up relationship exists between
forward/aft movement of the stick control member and up/down
movement of the reversing bucket, and a second mode in which a
non-follow-up relationship exists between forward/aft movement of
the stick control member and up/down movement of the reversing
bucket.
[0020] The nozzle position sensor, joystick, and control circuitry
may be configured to provide a follow-up relationship between the
rotation of the stick control member and rotation of the
nozzle.
[0021] The electrical circuitry may be configured to provide both a
docking mode and a power steer mode of operation, wherein in the
docking mode of operation, the bucket position sensor, nozzle
position sensor, and stick control member are configured so that
both bucket position control and nozzle position control have a
follow-up relationship to the respective movements of the stick
control member, and wherein in the power steer mode of operation,
the bucket position sensor, nozzle position sensor, and stick
control member are configured so that bucket position control is
non-follow-up and nozzle position control is follow-up.
[0022] In the power steer mode of operation, the electrical
circuitry and stick control member may be configured so that
rotational movement of the stick member produces less rotation of
the nozzle than in the docking mode.
[0023] A trim adjustment control may be provided to permit the
operator to adjust an offset between nozzle position and joystick
rotation.
[0024] Hydraulic cylinders may be used to position the bucket
and/or nozzle, and the components may be configured to provide two
speeds of movement of the hydraulic cylinder, a high speed movement
for use when the cylinder is more than a predetermined distance
away from the position prescribed by the control circuitry, and a
low speed movement for use when the cylinder is less than the
predetermined distance.
[0025] Other features and advantages of the invention will be
apparent from the following description of preferred embodiments,
and from the claims.
BRIEF DESCRIPTION OF THE DRAWING
[0026] FIG. 1A is an elevation view of a prior art boat equipped
with a waterjet drive and bowthruster.
[0027] FIG. 1B is a plan view of the same prior art boat.
[0028] FIGS. 2A, 2B, and 2C are enlarged, diagrammatic, elevation
views of the waterjet and reversing bucket of FIG. 1A, showing the
bucket in three different positions.
[0029] FIGS. 3A-3F are enlarged, diagrammatic, plan views of the
waterjet and reversing bucket of FIG. 1B, showing the nozzle in
three different positions for the case of the reversing bucket
being all of the way up (maximum forward thrust; FIGS. 3A-3C) and
all of the way down (maximum reverse thrust; FIGS. 3D-F).
[0030] FIG. 4 is an overall electrical and hydraulic schematic of a
preferred embodiment of the invention.
[0031] FIG. 5 is a schematic of the hydraulic valve assembly used
to control the position of the reversing bucket of the preferred
embodiment.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0032] A boat 10 with a waterjet drive 12 and bowthruster 16 is
shown in FIGS. 1A and 1B. Water enters the drive through inlet 8,
and exits through nozzle 18.
[0033] FIGS. 2A-2C are enlarged views of the waterjet drive 12,
showing the reversing bucket 14 in full forward (FIG. 2A),
approximately neutral (FIG. 2B), and full reverse (FIG. 2C)
positions.
[0034] FIGS. 3A-3C show the waterjet nozzle 18 in three different
angular positions (the nozzle rotates about a generally vertical
axis) for the case in which the reversing bucket is all of the way
up: left sideways thrust (FIG. 3A), approximately neutral thrust
(FIG. 3B), and right sideways thrust (FIG. 3C). When the bucket is
all of the way up, the bucket is out of the way of the nozzle, and
thus does not show up in FIGS. 3A-3C. Nozzle thrust is
predominantly directed rearwardly, but a sideward component of
thrust is provided when the nozzle is angled to the left (FIG. 3A)
or right (FIG. 3C).
[0035] FIGS. 3D-3F show the waterjet nozzle 18 in the same three
angular positions for the case in which the reversing bucket is
fully down. The bucket has the effect of reversing the dominant
thrust direction, but the sideward component of thrust is
approximately the same as if the bucket were all of the way up
(e.g., the sideward component is approximately the same in FIGS. 3A
and 3D, and in 3C and 3F).
[0036] Electrical and Hydraulic Components
[0037] FIG. 4 shows the principal electrical and hydraulic
components of a preferred embodiment. The figure is organized in
three sections. The upper portion relates to control of the
waterjet nozzle 18; the middle, to control of the reversing bucket
14; the lower, to control of the bowthruster 16. Operator control
of the nozzle, bucket, and bowthruster is achieved using a joystick
20 and steering wheel 22. The joystick 20 has three independent
directions of movement: rotating or twisting movement about a
vertical axis, for control of the nozzle (upper section of FIG. 4);
forward/aft movement, for control of the bucket (middle of FIG. 4);
left/right (port/starboard) movement, for control of the
bowthruster (bottom of FIG. 4). In each direction of movement, a
centering force (or torque, in the case of rotation) returns the
joystick to a neutral, centered position when it is released. The
centering force is preferably provided by springs.
[0038] A mode selection switchpanel 24 is used by the operator to
vary the relationship between movements of the joystick and
movements of the nozzle and reversing bucket. The operator can
select from among three modes: Helm, Docking, and Power Steer
(using momentary, illuminated switches). Outputs from switchpanel
24 are fed to switching circuit 26, from which mode control outputs
MS1, MS2, MS3 are fed to various components of the system. Other
outputs (not shown) of the switching circuit perform various
conventional functions, e.g., controlling indicator lights on the
switchpanel. A row of 10 double-bright LEDs is also provided (not
shown) as a rough indicator of bucket position. A sustained
pushbutton switch is used to dim both switch lighting and the row
of LEDs. A small trim knob is used to offset the center position of
the nozzle in the Power Steer mode (it is connected to a 270 degree
potentiometer).
[0039] The switching circuit is contained on a printed circuit
board housed in an electronics enclosure. All other electrical
components in the system connect to this board, including joystick,
switchpanel 24, power supply leads, bowthruster contactors 94, 96
and autopilot output. A single sheathed cable leads aft from the
electronics enclosure to hydraulic solenoid valves 88, 90 in the
hydraulic valve assembly, and bucket and nozzle position sensors
46, 56. The circuit board supplies a regulated voltage to position
sensors and joystick. It contains a logic section of diodes and
relays to switch between modes, a set of comparison circuits 54, 76
to accomplish the follow-up action between joystick and the jet,
adjustments for calibrating the follow-up circuit, power switching
relays 50, 52, 70, 72, 74 to trigger the hydraulic solenoids 88, 90
and nozzle pump motor 36, electronic end stop circuits 48, 64 for
bucket and nozzle travel, and a circuit for dimming the switchpanel
display.
[0040] The hydraulic valve assembly is designed to mount near the
jet, although it could be mounted at any point that allows plumbing
between the hydraulic pump and bucket positioning cylinder. The
primary components are a priority flow controller 86, solenoid
cartridge valve 88 with one NO and one NC outlet, and a reversing
solenoid valve 90 with spring return to tandem center. Also
included on the plate is a junction box to connect solenoid valves,
bucket and nozzle position sensors and autopilot/nozzle pump.
[0041] The position sensors are sealed 5K ohm, 360 degree
potentiometers. These are preferably mounted so that they are in
the middle of their travel at neutral bucket and nozzle, as this
allows calibration of neutral bucket and neutral nozzle positions
by simply loosening the position sensor brackets and rotating the
sensors.
[0042] Operation
[0043] As noted earlier, three modes of operation are available,
selected by pressing buttons on the switchpanel: Helm, Docking, and
Power Steer. The primary difference between modes is the method of
controlling bucket and nozzle. In all three modes the bowthruster
is activated by deflecting the joystick left or right.
[0044] 1. Helm Mode
[0045] Helm is the default mode, which the system is in when power
is first supplied to the switching circuit 26. In Helm mode, the
boat is steered solely by the steering wheel (in conjunction with
the autopilot, if activated), and is the mode typically used
underway when the boat operator prefers to steer with the wheel.
Helm mode also serves as the failsafe mode in the event of a
failure of the joystick or switching circuit. The steering wheel is
connected hydraulically (in a conventional manner) to steering ram
30, which drives tiller arm 32, which, in turn, is mechanically
coupled to the waterjet nozzle. In Helm mode, control output MS1 is
low (i.e., zero volts), and thus autopilot relay 34 remains
unactivated, with the result that autopilot output signals are
passed to the autopilot pump 36, but inputs from the joystick and
associated electronics are blocked.
[0046] In Helm mode the reversing bucket functions in a
non-follow-up manner, i.e., forward or aft movement of the joystick
functions as a simple up/down directional switch for movement of
the bucket. Forward movement of the joystick causes the bucket to
move upward as long as the joystick is held forward of center.
Conversely, aft movement causes the bucket to move downwardly for
as long as the joystick is held aft of center. When the joystick is
at rest, i.e., in the neutral center position, the bucket remains
at its current orientation. Thus, tapping the joystick forward or
aft momentarily in Helm mode causes the bucket to move
incrementally upward or downward by a small amount and then remain
in that position.
[0047] In Helm mode control output MS3 is low, resulting in bucket
mode relay 38 being in a position in which 12 VDC is supplied to
joystick forward/aft switch 40. In this way, forward movement of
the joystick has the effect of delivering a 12 VDC signal to the
bucket up input line to hydraulic valve assembly 42, and aft
movement has the opposite effect, namely, delivering a 12 VDC
signal to the bucket down input line. The hydraulic valve assembly
is connected to hydraulic cylinder 44, which drives the bucket 14.
A bucket position sensor 46 provides an electrical signal
indicative of the position of the reversing bucket. The position
sensor signal is supplied to an end stop circuit 48, which
determines whether the limits of upward or downward travel of the
bucket have been exceeded, and, if so, activates the appropriate
end stop relay 50, 52, to prevent further movement of the
bucket.
[0048] 2. Docking Mode
[0049] Docking mode is the mode used for slow speed maneuvering,
e.g., in approaching a dock or slip. In this mode, both bucket and
nozzle are controlled by the joystick in a follow-up manner. Thus,
moving the joystick to a position (e.g., halfway forward) causes
the corresponding device (e.g., the bucket) to move to a
corresponding position (e.g., halfway up).
[0050] In Docking mode, twisting of the joystick produces rotation
of the nozzle. Twisting the joystick produces an output signal 79
that is compared by comparison circuit 54 to the output of position
sensor 56, which measures the position of the nozzle. The
comparison circuit produces speed and direction signals 58, 60,
which control motor drive circuit 62, which, in turn, supplies a
signal to autopilot pump 36. The result is that the nozzle moves
until the output of position sensor 56 matches the joystick output
signal. For example, if the joystick is twisted to the right from a
neutral position, there is initially a large difference in voltage
between the joystick output and the output of the tiller position
signal. This produces a movement of the nozzle in a direction that
causes the stern of the boat to move to port (left). As the nozzle
turns, the output of the tiller position signal increases until a
point is reached at which the amplitude of the position sensor
signal matches that of the joystick signal, at which point movement
of the nozzle ceases. To avoid the nozzle hunting back and forth
once it reaches a desired position, the comparison circuit 54 uses
pulse width modulation to drive the autopilot pump. When the nozzle
is far away from the desired position, a continuous signal is
delivered to the autopilot pump. When the nozzle gets within a
predetermined proximity to the desired position, the continuous
signal is replaced with a pulsed signal, which has the effect of
slowing down movement of the nozzle. Control output MS1 is high in
Docking mode, so that the autopilot relay blocks the autopilot
output signal, and instead drives the autopilot pump with the
output of the motor drive circuit. An end stop circuit 64 compares
the output of position sensor 56 to a stored voltage corresponding
to the ends of travel of the nozzle tiller arm 32, and activates
end stop relays 66 in the event that the tiller arm reaches one or
the other ends of its allowed travel. Trim circuit 68 is not active
in Docking mode (MS2 is low).
[0051] Bucket control in Docking mode is also done in a follow-up
manner. Control output MS3 controls bucket mode relay 38 SO that 12
VDC is supplied not to joystick switch 40 (as in the case of Helm
mode) but to relays 70, 72, 74, which control the outputs of
comparison circuit 76. The switch function of the joystick is
replaced with a forward/aft potentiometer output 78, which is
compared to the output of position sensor 46 by comparison circuit
76. The comparison circuit produces three outputs, a bucket-up
signal 80, a bucket-down signal 82, and a shift-to-high-speed
signal 84. With relays 70, 72, 74 activated, these three signals
are supplied to hydraulic valve assembly 42, to control movement of
the bucket. The result is that the bucket moves until the output of
the position sensor 46 matches the output 78 of the joystick. If,
for example, the joystick is moved forward from neutral and held in
that forward position, there would initially be a large difference
between the joystick output 58 and the output of the position
sensor. The comparison circuit would generate a bucket up signal
causing the hydraulic valve assembly 42 to move hydraulic cylinder
14 in a direction that would move the bucket upwardly. As the
bucket approached the upward position corresponding to the forward
position of the joystick, the difference between the joystick and
positions sensors signals would decrease, until finally movement of
the bucket would cease.
[0052] Hydraulic valve assembly 42 is capable of driving the bucket
at two rates of speed, a high rate that is used when the bucket is
far away from the position commanded by the joystick, and a low
rate of speed when the bucket is near the desired position. This
allows the bucket to be rapidly moved to a desired position, while
also being brought to rest without the vibration and noise
associated with stopping a fast moving hydraulic cylinder. The dual
speed control is achieved using the hydraulic components shown in
FIG. 5. There are four hydraulic connections to the valve assembly:
supply 100 from the hydraulic pump, return 102 to the hydraulic
reservoir tank, and connections 104, 106 to each side of the
hydraulic cylinder 44. A reversing solenoid valve 90 governs the
direction in which fluid is supplied to the cylinder. A bucket up
signal drives the valve in one direction, and a bucket down signal
drives the valve in the reverse direction. The rate of flow of
hydraulic fluid through the solenoid valve is governed by a second
valve 88, working in conjunction with a flow regulator 86. The
regulator divides the incoming supply flow into a controlled flow
output CF and an excess flow output EF. The controlled flow output
CF is always delivered to the reversing solenoid valve 90, but when
the shift-to-high-speed signal is supplied to valve 88, the excess
flow output is combined with the controlled flow output, to
increase the rate of flow. Solenoid valve 88 accomplishes this by
moving from the position drawn in FIG. 5 (in which the excess flow
output is returned to the reservoir) to a position in which the
excess flow is connected to the controlled flow output. In that
position, the excess flow EF is routed back to and summed with the
controlled flow CF.
[0053] 3. Power Steer Mode
[0054] The third mode of operation is the Power Steer mode, in
which the boat operator steers underway using the joystick rather
than the wheel. Bucket control is the same as in Helm mode, i.e.,
non-follow-up (the joystick works as a up/down switch to control
the reversing bucket). Nozzle control is similar to Docking mode,
except that a trim circuit 68 is activated by control output MS2.
The trim circuit reduces the sensitivity of the joystick, so that
the same degree of twist in Power Steer produces less nozzle
movement than in Docking. Also, a trim potentiometer (not shown) on
the control panel is activated, allowing the operator to adjust the
nozzle position that corresponds to zero twist of the joystick.
This allows the operator to make small adjustments to the boat's
track, e.g., to compensate for the effect of crosswind or current
(without requiring that the operator maintain a slight twist on the
joystick).
[0055] The bowthruster 16 operates the same in all modes, but is
only normally useful in the slow speed maneuvering associated with
the Docking mode. Left/right (port/starboard) movements of the
joystick activate switch 92, which delivers 12 VDC to either the
port contactor 94 or the starboard contactor 96. When activated
contactors 94, 96 connect high power to the bowthruster motor.
Contactor 94 delivers high power of one polarity, and contactor 96
delivers high power in the opposite polarity. The result is that
port deflection of the joystick produces bowthruster action causing
movement of the bow to port, and starboard deflection, movement of
the bow to starboard. It has been found that a small amount of
deadband in the left/right movement of the joystick is preferable,
so that small left/right movements, such as those unavoidably
associated with forward/aft and twisting movements, do not
inadvertently activate the bowthruster.
[0056] Other embodiments are within the scope of the following
claims.
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