BACKGROUND OF THE INVENTION
1. FIELD OF THE INVENTION
[0001] The present invention relates to a fin stabilizer for a vessel for suppressing a
rocking motion of the vessel body.
2. DESCRIPTION OF RELATED ART
[0003] Conventionally, as an apparatus for suppressing the rolling motion and pitching motion
of a vessel body there is known, for example, a fin stabilizer (for example, refer
to
Japanese Unexamined Patent Application, First Publication No. H08-324485). This fin stabilizer has a fin provided on and projecting from an outer panel of
the vessel and by controlling an angle of this fin a lifting force is generated to
suppress the rolling motion of the vessel body.
[0004] In such a fin stabilizer, a fin angle with respect to sea water flow (hereunder referred
to as "angle of attack") and a fin angle with respect to the vessel body (hereunder
referred to as "fin angle") are treated as identical, and anti-rolling control for
the vessel is carried out by controlling the fin angle based on the rocking motion
of the vessel body.
[0005] However, under the influence of wave disturbance and motion of the vessel body, the
above angle of attack and fin angle may not match in some cases. In this case, in
the above mentioned conventional fin stabilizer, there has been a problem in that
the fin angle cannot be controlled at an appropriate angle and a required lifting
force for suppressing rocking motion of the vessel body cannot be achieved.
BRIEF SUMMARY OF THE INVENTION
[0006] An object of the present invention is to provide a fin stabilizer for a vessel that
can suppress the rocking motion of a vessel body with a high level of accuracy by
obtaining a required lifting force, and a control method and control program therefor.
[0007] A first aspect of the present invention is a fin stabilizer for a vessel comprising
a fin attached to a vessel body for reducing a rocking motion of the vessel body,
and a fin driving device having a hydraulic cylinder for adjusting an angle of the
fin with respect to the vessel body, wherein the fin stabilizer comprises: a pressure
detection section that detects a pressure in the hydraulic cylinder; a torque calculation
section that calculates a torque of the fin; a fin angle estimation section that estimates
an angle of the fin with respect to a flow of sea water based on the calculated torque;
and a command generation section that generates a fin angle command value for matching
the estimated fin angle with a target angle for counteracting the rocking motion of
the vessel body, and the fin driving device drives the fin based on the fin angle
command value.
[0008] According to this aspect, the torque calculation section calculates a fin torque
based on the pressure of the hydraulic cylinder, and the fin angle estimation section
estimates a fin angle with respect to the flow of sea water, that is, an angle of
attack, based on the torque. Moreover, the command generation section generates a
fin angle command value for matching this angle of attack with the target angle, and
the fin driving device drives the fin based on this fin angle command value. Thus,
by controlling the fin angle based on the angle of attack, which directly relates
to a lifting force, it becomes possible to attain the required lifting force, and
the accuracy of the anti-rolling control can be improved.
[0009] Here, there is a correlation between the lifting force that acts on the fin and the
fin torque. Furthermore, there is a correlation between the pressure of the hydraulic
cylinder and the fin torque. Therefore, the fin torque can be obtained from the pressure
of the hydraulic cylinder, and the lifting force that acts on the fin can be obtained
from this torque. Moreover, since the lifting force that acts on the fin is determined
by the angle of attack of the fin, the angle of attack of the fin can be estimated
from the fin torque.
[0010] The fin stabilizer for a vessel may be further comprise a fin angle detection section
that detects an angle of the fin with respect to the vessel body, and in the case
where a rocking motion cycle of the vessel body is less than or equal to a preset
predetermined threshold value, the command generation section may generate a fin angle
command value for matching the fin angle detected by the fin angle detection section
with the target angle.
[0011] In the case where the rocking motion cycle is less than or equal to a predetermined
cycle, it is possible that torque calculation accuracy may decline due to a reduction
in accuracy of the pressure detection carried out by the pressure detection section,
in turn resulting in a reduction in reliability of the fin angle estimated by the
fin angle estimation section. In such cases, anti-rolling control is carried out based
on the fin angle with respect to the vessel body to maintain the level of accuracy
substantially equal to that of the conventional fin stabilizer.
[0012] In the fin stabilizer for a vessel, the pressure detection section may comprise:
a pressure sensor that respectively detects pressures in an upper cylinder chamber
and a lower cylinder chamber of the hydraulic cylinder; and a noise removal section
that removes a noise component contained in a detection value detected by the pressure
sensor, and the predetermined threshold value may be determined based on the performance
of the noise removal section.
[0013] The performance of the noise removal section changes depending on the rocking motion
cycle. Therefore, within a range where the performance of the noise removal section
is reduced, that is, at the time of a rocking motion cycle within which a required
pressure detection accuracy cannot be maintained, anti-rolling control is carried
out based on the fin angle with respect to the vessel body.
[0014] The above fin stabilizer for a vessel may further comprise: a fin angle detection
section that detects an angle of the fin with respect to the vessel body; and a difference
calculation section that finds a difference between an angle of the fin with respect
to a sea water flow estimated by the fin angle estimation section and an angle of
the fin with respect to the vessel body detected by the fin angle detection section,
and in a case where the difference is greater than or equal to a preset predetermined
value, the command generation section may generate a fin angle command value for matching
the fin angle with respect to the vessel body detected by the fin angle detection
section, with the target angle.
[0015] According to the above configuration, the difference calculation section finds the
difference between the angle of the fin detected by the fin angle detection section,
that is, the fin angle, and the angle of the fin estimated by the fin angle estimation
section, that is, the angle of attack, and, in the case where this difference is greater
than or equal to the preset predetermined value, the command generation section generates
a fin angle command value based on the above fin angle. Thus, in the case where the
fin angle and the angle of attack both have significant errors, control is stabilized
by carrying out fin control based on the fin angle and not on the angle of attack.
[0016] A second aspect of the present invention is a control method for a fin stabilizer
for a vessel that comprises a fin attached to a vessel body for reducing a rocking
motion of the vessel body, and a fin driving device having a hydraulic cylinder for
adjusting an angle of the fin with respect to the vessel body, wherein the control
method comprises: a step for calculating a torque of the fin based on a pressure of
the hydraulic cylinder; a step for estimating an angle of the fin with respect to
a flow of sea water based on the calculated torque; a step for generating a fin angle
command value for matching the estimated fin angle with a target angle for counteracting
the rocking motion of the vessel body; and a step for controlling the fin driving
device based on the fin angle command value.
[0017] According to the above control method, the fin torque is calculated based on the
pressure of the hydraulic cylinder, and the fin angle with respect to the sea water
flow, that is, the angle of attack directly relating to a lifting force, is estimated
based on this calculated torque. Moreover, a fin angle command value for matching
this angle of attack with the target angle is generated, and the fin driving device
drives the fin based on this fin angle command value. As a result, the required lifting
force can be obtained, and the accuracy of anti-rolling control can be improved.
[0018] A third aspect of the present invention is a control program for a fin stabilizer
for a vessel that comprises a fin attached to a vessel body for reducing a rocking
motion of the vessel body, and a fin driving device having a hydraulic cylinder for
adjusting an angle of the fin with respect to the vessel body, for executing on a
computer: a step for calculating a torque of the fin based on a pressure of the hydraulic
cylinder; a step for estimating an angle of the fin with respect to a flow of sea
water based on the calculated torque; a step for generating a fin angle command value
for matching the estimated fin angle with a target angle for counteracting the rocking
motion of the vessel body; and a step for controlling the fin driving device based
on the fin angle command value.
[0019] By executing the above control program by a computer, the fin torque is calculated
based on the pressure of the hydraulic cylinder, and the fin angle with respect to
the sea water flow, that is, the angle of attack directly relating to a lifting force
is estimated based on this calculated torque. Moreover, a fin angle command value
for matching this angle of attack with the target angle is generated, and the fin
driving device drives the fin based on this fin angle command value. As a result,
the required lifting force can be obtained, and the accuracy of anti-rolling control
can be improved.
[0020] According to the present invention, since it becomes possible to achieve the required
lifting force, an effect can be achieved in which the rocking motion of the vessel
body can be suppressed with a high level of accuracy.
BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS
[0021] FIG. 1 is a control block diagram for explaining an effect of a fin stabilizer for
a vessel according to a first embodiment of the present invention, on a vessel body.
[0022] FIG. 2 is a diagram schematically showing a mechanical configuration of the fin stabilizer
according to a first embodiment of the present invention.
[0023] FIG. 3 is a block diagram showing a control system of a fin stabilizer according
to the first embodiment of the present invention.
[0024] FIG. 4 is a diagram showing an example of a moment coefficient table illustrating
a correlation between a moment coefficient Cm and an angle of attack θ2.
[0025] FIG. 5 is an explanatory diagram for explaining parameters used in a calculation
expression of the moment coefficient.
[0026] FIG. 6 is a block diagram showing a control system of a fin stabilizer according
to a second embodiment of the present invention.
DETAILED DESCRIPTION OF THE INVENTION
[0027] Hereinafter, embodiments of a fin stabilizer for a vessel according to the present
invention are described, with reference to the drawings.
First embodiment
[0028] Hereunder, a fin stabilizer for a vessel according to a first embodiment of the present
invention is described.
[0029] FIG. 1 is a control block diagram for explaining an effect of a fin stabilizer for
a vessel (hereunder referred to as "fin stabilizer") according to the present embodiment,
on a vessel body.
[0030] As shown in this diagram, a sensor (not shown in the diagram) provided on a vessel
body 2 detects an actual inclination angle φ of the vessel body 2 and enters it into
a target inclination angle generation section 50. In the target inclination angle
generation section 50, an inclination angle command value φ' for matching the actual
inclination angle φ of the vessel body 2 to a target inclination angle φref (=0) is
calculated, and this inclination angle command value φ' is outputted to a fin stabilizer
1. The target inclination angle generation section 50, for example, outputs a difference
between the target inclination angle φref and the actual inclination angle φ of the
vessel body 2 as the inclination angle command value φ'. In the fin stabilizer 1,
as described later, by controlling the angle of the fin based on the inclination angle
command value φ', a lifting force, which makes the inclination angle of the vessel
body 2 zero, is generated to suppress the rocking motion of the vessel body 2.
[0031] In the above fin stabilizer 1, as shown in FIG. 2, a fin 11 is pivoted about a pivot
axis by a hydraulic cylinder 12. This hydraulic cylinder 12 has a piston P. This piston
P is configured to move in reciprocal motion within the hydraulic cylinder 12, based
on a positive/negative direction flow and a flow rate Q of operating oil supplied
from a constant discharge pump 13 via a flow rate adjusting mechanism 14 (provided
for example with an electro-hydraulic servo valve). The flow rate Q of the discharged
oil is adjusted by the flow rate adjusting mechanism 14.
[0032] According to such a configuration, when the flow rate Q is adjusted by the flow rate
adjusting mechanism 14, the piston P of the hydraulic cylinder 12 moves in an up-down
direction, and an angle θ of the fin 11 is adjusted to the required angle.
[0033] In an upper cylinder chamber 12a of the hydraulic cylinder 12, an upper side pressure
sensor 16a is provided to detect the oil pressure inside the hydraulic cylinder. Similarly,
in a lower cylinder chamber 12b of the hydraulic cylinder 12, a lower side pressure
sensor 16b is provided to detect the oil pressure inside the hydraulic cylinder.
[0034] Next, a control system of the fin stabilizer according to the above described present
embodiment is described with reference to FIG. 3. FIG. 3 is a block diagram showing
a control system of a fin stabilizer according to the present embodiment. In FIG.
3, components the same as those shown in FIG. 2 mentioned above are denoted by the
same reference symbols.
[0035] First, the inclination angle command value φ' shown in FIG. 1 is inputted to a fuzzy
computing unit 21 and a differentiation unit 22 of the fin stabilizer 1 shown in FIG.
3. The differentiation unit 22 differentiates the inclination angle command value
φ' and outputs this to the fuzzy computing unit 21. The fuzzy computing unit 21 finds
the fin angle required to make the inclination angle φ of the vessel body 2 zero,
and outputs this as a target fin angle θ1. For a computing procedure performed by
the fuzzy computing unit 21, for example, the method disclosed in
Japanese Patent No. 2915658 may be employed.
[0036] The target fin angle θ1 outputted from the fuzzy computing unit 21 is inputted to
a command generation section 23. The command generation section 23 compares the above
target fin angle θ1 with a fin angle of attack (hereunder, referred to as "estimated
angle of attack"; angle of attack is the angle of the fin 11 with respect to sea water
flow.) θ2' estimated by an angle of attack computing unit 24 described later, and
finds a fin angle command value θ3 for matching the estimated angle of attack θ2'
with the target fin angle θ1.
[0037] The fin angle command value θ3 found by the command generation section 23 is inputted
to the flow rate adjusting mechanism 14. The flow rate adjusting mechanism 14 operates
to supply operating oil to the hydraulic cylinder 12 at a flow rate Q corresponding
to the fin angle command value θ3. Accordingly, the flow rate Q corresponding to the
fin angle command value θ3 is supplied to the hydraulic cylinder 12, and an actual
fin angle (hereunder referred to as "actual fin angle"; fin angle is the angle of
the fin 11 with respect to the vessel body.) θ3' of the fin 11 changes. By changing
the fin angle θ3' under the influence of a disturbance W or the like of the sea water,
it becomes the fin angle with respect to sea water, that is, the actual fin angle
of attack θ2. A lifting force acts according to this fin angle of attack θ2 and suppresses
the rocking motion of the vessel body.
[0038] On the other hand, in order to feedback-control this actual fin angle of attack θ2,
first, the upper side pressure sensor 16a detects the pressure in the upper side cylinder
chamber of the hydraulic cylinder 12, and the lower side pressure sensor 16b detects
the pressure in the lower side cylinder chamber. A higher harmonic wave (noise component)
is removed from these detected values by respectively passing them through low-pass
filters 25, and these detected values are inputted to a subtracter 26. The subtracter
26 computes a pressure difference between the upper and lower cylinder chambers of
the hydraulic cylinder 12, and the pressure difference that results from this computation
is inputted to a torque computing unit 27. The torque computing unit 27 calculates
the torque acting on the fin 11 based on the pressure difference between the upper
and lower cylinder chambers of the hydraulic cylinder 12, and outputs this calculated
torque. A torque adjusting unit 28 subtracts a self-weight torque component, which
is a torque based on a self-weight of the fin, from the torque computed by the torque
computing unit 27, after which the result is inputted to the angle of attack computing
unit 24.
[0039] The angle of attack computing unit 24 estimates the angle of attack θ2 of the fin
11 based on the torque inputted from the torque adjusting unit 28.
[0040] The angle of attack computing unit 24 has, for example, as shown in FIG. 4, a moment
coefficient table for associating a moment coefficient Cm relating to a moment M which
acts on the fin 11, with the angle of attack θ2. Here, since the relationship between
the moment coefficient Cm and the angle of attack θ2 changes with a flow velocity
v of the sea water, these associations are made according to the flow velocity v of
sea water.
[0041] Here, the moment coefficient Cm can be obtained from the following expression (1).
[0042] Here, various kinds of parameters used in the above expression (1) are described,
with reference to FIG. 5. FIG. 5 is a diagram, which shows a vertical sectional view
of the fin 11, for explaining a force that acts on the fin 11. In this diagram, the
arrow G denotes a traveling direction of the vessel body 2.
[0043] In the above expression (1), the parameter M is a moment that acts on the fin 11
as shown in FIG. 5. In the present embodiment, a torque of the fin 11 inputted to
the angle of attack computing unit 24 is employed as the moment M. Moreover, the parameter
ρ represents the density of the sea water. For example, 1025kg/m
3 is used for this. The parameter v is the flow velocity of the sea water. In the present
embodiment, the vessel speed is used for this. The direction of the flow velocity
of the sea water and the direction of the vessel velocity are opposite as shown in
FIG. 5. The parameter A denotes a surface area of the fin 11. For example, an example
of the surface area is shown as a square in the upper section of FIG. 5. The parameter
C denotes a length of the fin 11 in the direction of sea water flow. Among the above
various kinds of parameters, the parameters ρ, A, and C are pre-recorded as constant
values, and the parameters v and M are values that reflect the speed and torque of
the vessel in real time.
[0044] The angle of attack computing unit 24, on input of a torque from the torque adjusting
unit 28, inputs this torque into the above expression (1) as the parameter M, and
inputs the vessel speed v at this point in time into the above expression (1), and
calculates the moment coefficient Cm. Subsequently, the angle of attack computing
unit 24 obtains the angle of attack θ2 corresponding to this moment coefficient Cm
and vessel speed v from the moment coefficient table shown in FIG. 4. Thus, when the
angle of attack θ2 of the fin 11 has been obtained, the angle of attack computing
unit 24 outputs the angle of attack θ2 as an estimated angle of attack, that is, an
estimated angle of attack θ2'.
[0045] Then this estimated angle of attack θ2' is fed back to the command control section
23 shown in FIG. 3.
[0046] Subsequently, the command generation section 23 calculates the fin angle command
value θ3 for matching the estimated angle of attack θ2', which is fed back from the
angle of attack computing unit 24, with the target fin angle θ1 inputted from the
fuzzy computing unit 21. By outputting this fin angle command value to the flow rate
adjusting mechanism 14, the fin angle is adjusted based on the fin angle command value
θ3. As a result, it becomes possible to match the actual angle of attack θ2 of the
fin 11 with the target fin angle θ1. Accordingly, a required lifting force F can be
generated due to the effect of the fin, and it becomes possible to suppress the rocking
motion of the vessel body 2.
[0047] As described above, according to the fin stabilizer according to the present embodiment,
the fin angle after various kinds of disturbances W such as currents have acted, that
is, the angle of attack, is estimated, and then feedback control for the fin angle
is carried out based on this estimated angle of attack θ2'. Therefore a reduction
in lifting force due to the disturbance W can be eliminated and the accuracy of the
anti-rolling control can be improved.
Second embodiment
[0048] Next, a second embodiment of the present invention is described, with reference to
FIG. 6.
[0049] A fin stabilizer of the present embodiment differs from that of the first embodiment
in that in the feed back system, a predetermined condition is added, and the fin angle
to be fed back is switched between either the estimated angle of attack θ2' or the
actual fin angle θ3' according to this condition.
[0050] For the fin stabilizer according to the present embodiment, in the case where, for
example, a difference between the estimated angle θ2' and the actual fin angle θ3'
is less than or equal to a predetermined value (for example, 2°) and a rocking motion
cycle of the vessel body 2 (refer to FIG. 1) is greater than or equal to a preset
predetermined threshold value (for example, 20 seconds), the estimated angle of attack
θ2' is fed back.
[0051] Conversely, in the case where the above condition is not satisfied, that is, in the
case where the difference between the estimated angle of attack θ2' and the actual
fin angle θ3' exceeds the predetermined value (for example, 2°) or in the case where
the rocking motion cycle of the vessel body 2 (refer to FIG. 1) is less than or equal
to the preset predetermined threshold value (for example, 20 seconds), the actual
fin angle θ3' is fed back to the fin stabilizer instead of the estimated angle of
attack.
[0052] For example, in the case where the rocking motion cycle of the vessel body is short,
it becomes difficult to remove a higher harmonic wave contained in the sensor output
from each of the pressure sensors 16a and 16b using the low-pass filter 25. Consequently,
in the present embodiment, for the range within which pressures in the upper and lower
cylinder chambers of the hydraulic cylinder cannot be detected at a high level of
accuracy, feed back control is carried out based on the actual fin angle θ3' and not
on the estimated angle of attack θ2'. Therefore, for example, the predetermined threshold
value under the above condition is determined by the performance of the low-pass filter.
[0053] Moreover, in the case where the estimated angle of attack θ2' is significantly different
from the actual fin angle θ3', there is a possibility of a malfunction of the pressure
sensor. Furthermore, since there is a possibility of a reduction in control stability,
then in the present embodiment control stability is maintained by feeding back the
estimated angle of attack θ2' only when the difference between both of these angles
is within a range of a predetermined value.
[0054] Next, an example of a specific configuration of the fin stabilizer for a vessel according
to the present embodiment is described with reference to the diagrams. FIG. 6 is a
diagram showing a control system of the fin stabilizer according to the present embodiment.
In FIG. 6, components the same as those shown in FIG. 3 are denoted by the same reference
symbols, and description thereof is omitted.
[0055] In the fin stabilizer according to the present embodiment, as shown in FIG. 6, a
subtracter 30, a limiter 31, and a switcher 32 are provided on a feedback line that
connects the angle of attack computing unit 24 to the command generation section 23'.
[0056] First, the estimated angle of attack θ2' estimated by the angle of attack computing
unit 24 is inputted to the subtracter 30. The subtracter 30 calculates the difference
between the estimated angle of attack θ2' and the actual fin angle θ3'. The actual
fin angle θ3' is that detected by a commonly known technique, and the actual fin angle
θ3' detected by the commonly known technique may be used.
[0057] A difference θ2'-θ3' calculated by the subtracter 30 is inputted to the limiter 31.
The limiter 31 performs comparison and determines whether or not the difference θ2'-θ3'
is less than or equal to a predetermined value (for example, 2°). If the difference
is less than or equal to the predetermined value, then the limiter 31 outputs the
difference to the switcher 32, and if the difference exceeds the predetermined value,
it outputs "zero" to the switcher 32.
[0058] To continue, the switcher 32 is a switch that switches in response to the rocking
motion cycle of the vessel body 2. In the case where the rocking motion cycle of the
vessel body 2 exceeds the predetermined threshold value, the switcher 32 outputs the
difference inputted from the limiter 31 to a first subtracter 23a provided for the
command generation section 23'. Conversely, in the case where the rocking motion cycle
of the vessel body 2 is less than or equal to the predetermined threshold value, the
switcher 32 outputs "zero" to the first subtracter 23a of the command generation section
23'.
[0059] As a result, in the case where the difference between the estimated angle of attack
θ2' and the actual fin angle θ3' is less than or equal to the predetermined value
(for example 2°) and the rocking motion cycle of the vessel body 2 is greater than
or equal to the threshold value, the difference θ2'-θ3' calculated by the subtracter
30 is fed back from the switcher 32 to the first subtracter 23a of the command generation
section 23'. The first subtracter 23a of the command generation section 23' calculates
the difference θ1-(θ2'-θ3') between the difference θ2'-θ3' inputted from the switcher
32 and the target fin angle θ1 inputted from the fuzzy computing unit 21, and outputs
this calculation result to a second subtracter 23b provided for the command generation
section 23'. The second subtracter 23b calculates the difference between the difference
θ1-(θ2'-θ3') inputted from the first subtracter 23a and the actual fin angle θ3',
that is, θ1-(θ2'-θ3')-θ3'=θ1-θ2', and outputs this calculation result θ1-θ2' as a
fin angle command value θ3 to the flow rate adjusting mechanism 14. That is to say,
in this case the fin angle to be fed back becomes equal to the estimated angle of
attack θ2'.
[0060] On the other hand, in the case where the difference between the estimated angle of
attack θ2' and the actual fin angle θ3' is greater than the predetermined value (for
example, 2°), or in the case where the rocking motion cycle of the vessel body 2 is
less than the threshold value, the signal to be fed back to the first subtracter 23a
of the command generation section 23' becomes "zero". Accordingly, the calculation
result of the first subtracter 23a of the command generation section 23' becomes θ1-0=θ1,
and the target fin angle θ1 is inputted to the second subtracter 23b. The second subtracter
23b calculates the difference between the target fin angle θ1 and the actual fin angle
θ3', that is, θ1-θ3', and outputs this calculation result θ1-θ3' as the fin angle
command value θ3 to the flow rate adjusting mechanism 14. That is to say, in this
case, the fin angle to be fed back becomes equal to the actual fin angle θ3'.
[0061] Accordingly, in the case where the difference between the estimated angle of attack
θ2' and the actual fin angle θ3' is less than or equal to the predetermined value
(for example, 2°) and the rocking motion cycle of the vessel body 2 (refer to FIG.1)
is greater than or equal to a preset predetermined value, fin angle control is carried
out based on the estimated angle of attack θ2'. On the other hand, in the case where
the difference between the estimated angle of attack θ2' and the actual fin angle
θ3' exceeds the predetermined value, or where the rocking motion cycle of the vessel
body 2 is less than the predetermined threshold value, fin angle control is carried
out based on the actual fin angle θ3'.
[0062] As described above, according to the fin stabilizer according to the present embodiment,
in the case where the rocking motion cycle is less than or equal to a predetermined
cycle and pressures in the upper and lower cylinder chambers of the hydraulic cylinder
12 cannot be detected at a high level of accuracy, anti-rolling control is carried
out based on the actual fin angle θ3', enabling the level of accuracy to be maintained
substantially equal to that of the conventional fin stabilizer. Furthermore, in the
case where the difference between the actual fin angle θ3' and the estimated angle
of attack θ2' is less than or equal to the predetermined value, control can be stabilized
since anti-rolling control is carried out based on the actual fin angle θ3'.
[0063] The fin stabilizer according to the above first embodiment and second embodiment
may have an internal computer system. Furthermore, the series of processing steps
relating to the above described stabilizer control may be stored on a computer-readable
recording medium in a computer program format, and the above processing may be performed
by loading this program onto a computer and executing it.
[0064] Specifically, each of the computing sections in the fin stabilizer control system
may be realized by having a central processing device such as a CPU load the above
program on a main memory device such as a ROM or RAM, to execute information processing
or computing processing.
[0065] Here a computer-readable recording medium refers to media such as a magnetic disk,
an optical magnetic disk, a CD-ROM, a DVD-ROM, or a semiconductor memory.
[0066] The embodiments of the present invention have been described in detail with reference
to the drawings. However, its specific configuration is not limited to these embodiments,
and it includes design modifications that do not depart from the scope of the present
invention.
[0067] For example, in the above first embodiment, the angle of attack is estimated based
on the moment coefficient table shown in FIG. 4. However, this is not limited to this
example and the angle of attack may be derived using an operational expression for
example. Moreover, as shown in FIG. 4, for example, the angle of attack has a proportional
relationship to the moment coefficient, where the moment coefficient is less than
or equal to a predetermined value. Therefore, in the case where the moment coefficient
is less than or equal to the predetermined value, the angle of attack may be easily
calculated based on an operational expression, that is, by multiplying the moment
coefficient by a predetermined coefficient. Moreover, in the case where the moment
coefficient exceeds the predetermined value, a corresponding angle of attack may be
found based on a moment coefficient table such as the one shown in FIG. 4.
1. A fin stabilizer (1) for a vessel comprising a fin attached to a vessel body (2) for
reducing a rocking motion of the vessel body, and a fin driving device having a hydraulic
cylinder (12) for adjusting an angle of the fin with respect to the vessel body,
characterized in that the fin stabilizer comprises:
a pressure detection section (16a,16b) that detects a pressure in the hydraulic cylinder;
a torque calculation section (27) that calculates a torque of the fin;
a fin angle estimation section (24) that estimates an angle of the fin with respect
to a flow of sea water based on the calculated torque; and
a command generation section (23) that generates a fin angle command value (θ3) for
matching the estimated fin angle (θ2') with a target angle (θ1) for counteracting
the rocking motion of the vessel body,
and the fin driving device (12) drives the fin based on the fin angle command value.
2. A fin stabilizer according to claim 1, further comprising a fin angle detection section
that detects an angle of the fin with respect to the vessel body, and
in the case where a rocking motion cycle of the vessel body is less than or equal
to a preset predetermined threshold value, the command generation section generate
a fin angle command value for matching the fin angle detected by the fin angle detection
section with the target angle.
3. A fin stabilizer according to claim 2, wherein the pressure detection section comprises:
a pressure sensor that respectively detects pressures in an upper cylinder chamber
and a lower cylinder chamber of the hydraulic cylinder; and
a noise removal section that removes a noise component contained in a detection value
detected by the pressure sensor,
and the predetermined threshold value is determined based on the performance of the
noise removal section.
4. A fin stabilizer according to claim 1 further comprising:
a fin angle detection section that detects an angle of the fin with respect to the
vessel body; and
a difference calculation section that finds a difference between an angle of the fin
with respect to a sea water flow estimated by the fin angle estimation section and
an angle of the fin with respect to the vessel body detected by the fin angle detection
section,
and in a case where the difference is greater than or equal to a preset predetermined
value, the command generation section generates a fin angle command value for matching
the fin angle with respect to the vessel body detected by the fin angle detection
section, with the target angle.
5. A control method for a fin stabilizer for a vessel that comprises a fin attached to
a vessel body for reducing a rocking motion of the vessel body, and a fin driving
device having a hydraulic cylinder for adjusting an angle of the fin with respect
to the vessel body, wherein the control method comprises:
a step for calculating a torque of the fin based on a pressure of the hydraulic cylinder;
a step for estimating an angle of the fin with respect to a flow of sea water based
on the calculated torque;
a step for generating a fin angle command value for matching the estimated fin angle
with a target angle for counteracting the rocking motion of the vessel body; and
a step for controlling the fin driving device based on the fin angle command value.
6. A control program for a fin stabilizer for a vessel that comprises a fin attached
to a vessel body for reducing a rocking motion of the vessel body, and a fin driving
device having a hydraulic cylinder for adjusting an angle of the fin with respect
to the vessel body, for executing on a computer:
a step for calculating a torque of the fin based on a pressure of the hydraulic cylinder;
a step for estimating an angle of the fin with respect to a flow of sea water based
on the calculated torque;
a step for generating a fin angle command value for matching the estimated fin angle
with a target angle for counteracting the rocking motion of the vessel body; and
a step for controlling the fin driving device based on the fin angle command value.
1. Flossenstabilisator (1) für ein Schiff, umfassend eine Flosse, die zur Verringerung
einer Schaukelbewegung des Schiffsrumpfes an einem Schiffsrumpf (2) befestigt ist,
und eine Flossenantriebsvorrichtung mit einem Hydraulikzylinder (12) zum Einstellen
eines Winkels der Flosse in bezug auf den Schiffsrumpf,
dadurch gekennzeichnet, daß der Flossenstabilisator umfaßt:
eine Druckerfassungseinheit (16a, 16b), die einen Druck in dem Hydraulikzylinder erfaßt,
eine Drehmomentberechnungseinheit (27), die ein Drehmoment der Flosse berechnet,
eine Flossenwinkelschätzeinheit (24), die einen Winkel der Flosse in bezug auf einen
Meerwasserstrom auf der Basis des berechneten Drehmoments abschätzt, und
eine Befehlserzeugungseinheit (23), die einen Flossenwinkelbefehlswert (θ3) zum Abgleichen
des geschätzten Flossenwinkels (θ2') mit einem Zielwinkel (θ1) erzeugt, um der Schaukelbewegung
des Schiffsrumpfes entgegenzuwirken,
wobei die Flossenantriebsvorrichtung (12) die Flosse auf der Basis des Flossenwinkelbefehlswerts
antreibt.
2. Flossenstabilisator nach Anspruch 1, ferner umfassend eine Flossenwinkelerfassungseinheit,
die einen Winkel der Flosse in bezug auf den Schiffsrumpf detektiert, wobei
die Befehlserzeugungseinheit dann, wenn ein Schaukelbewegungszyklus des Schiffsrumpfes
kleiner als ein vorher einstellter, vorgegebener Schwellwert oder gleich diesem ist,
einen Flossenwinkelbefehlswert zum Abgleichen des von der Flossenwinkelerfassungseinheit
detektierten Flossenwinkels mit dem Zielwinkel erzeugt.
3. Flossenstabilisator nach Anspruch 2, wobei der Druckerfassungseinheit folgendes umfaßt:
einen Drucksensor, mit dem jeweils Drücke in einer oberen Zylinderkammer und einer
unteren Zylinderkammer des Hydraulikzylinders detektiert werden, und
eine Rauschbeseitigungseinheit, mit dem eine Rauschkomponente beseitigt wird, die
in einem von dem Drucksensor detektierten Erfassungswert enthalten ist,
wobei der vorgegebene Schwellwert auf der Basis der Leistung der Rauschbeseitigungseinheit
bestimmt wird.
4. Flossenstabilisator nach Anspruch 1, ferner umfassend:
eine Flossenwinkelerfassungseinheit, die einen Winkel der Flosse in bezug auf den
Schiffsrumpf detektiert, und
eine Differenzberechnungseinheit, die eine Differenz zwischen einem Winkel der Flosse
in bezug auf einen Meerwasserstrom, der von der Flossenwinkelschätzeinheit geschätzt
wird, und einem Winkel der Flosse in bezug auf den Schiffsrumpf feststellt, der von
der Flossenwinkelerfassungseinheit detektiert wird,
wobei die Befehlserzeugungseinheit dann, wenn die Differenz größer als ein vorher
eingestellter, vorgegebener Wert oder gleich diesem ist, einen Flossenwinkelbefehlswert
zum Abgleichen des von der Flossenwinkelerfassungseinheit in bezug auf den Schiffsrumpf
detektierten Flossenwinkels mit dem Zielwinkel erzeugt.
5. Steuerungsverfahren für einen Flossenstabilisator für ein Schiff, der eine Flosse,
die zur Verringerung einer Schaukelbewegung des Schiffsrumpfes an einem Schiffsrumpf
befestigt ist, und eine Flossenantriebsvorrichtung mit einem Hydraulikzylinder zum
Einstellen eines Winkels der Flosse in bezug auf den Schiffsrumpf umfaßt, wobei das
Steuerungsverfahren umfaßt:
einen Schritt zum Berechnen eines Drehmoments der Flosse auf der Basis eines Drucks
des Hydraulikzylinders,
einen Schritt zum Schätzen eines Winkels der Flosse in bezug auf einen Meerwasserstrom
auf der Basis des berechneten Drehmoments,
einen Schritt zum Erzeugen eines Flossenwinkelbefehlswertes zum Abgleichen des geschätzten
Flossenwinkels mit einem Zielwinkel, um der Schaukelbewegung des Schiffsrumpfes entgegenzuwirken,
und
einen Schritt zum Steuern der Flossenantriebsvorrichtung auf der Basis des Flossenwinkelbefehlswerts.
6. Steuerungsprogramm für einen Flossenstabilisator für ein Schiff, der eine Flosse,
die zur Verringerung einer Schaukelbewegung des Schiffsrumpfes an einem Schiffsrumpf
befestigt ist, und eine Flossenantriebsvorrichtung mit einem Hydraulikzylinder zum
Einstellen eines Winkels der Flosse in bezug auf den Schiffsrumpf umfaßt, um an einem
Computer folgendes auszuführen:
einen Schritt zum Berechnen eines Drehmoments der Flosse auf der Basis eines Drucks
des Hydraulikzylinders,
einen Schritt zum Schätzen eines Winkels der Flosse in bezug auf einen Meerwasserstrom
auf der Basis des berechneten Drehmoments,
einen Schritt zum Erzeugen eines Flossenwinkelbefehlswertes zum Abgleichen des geschätzten
Flossenwinkels mit einem Zielwinkel, um der Schaukelbewegung des Schiffsrumpfes entgegenzuwirken,
und
einen Schritt zum Steuern der Flossenantriebsvorrichtung auf der Basis des Flossenwinkelbefehlswerts.
1. Stabilisateur à aileron (1) pour un navire comportant un aileron fixé sur un corps
de navire (2) afin de réduire un mouvement de basculement du corps de navire, et un
dispositif d'entraînement d'aileron ayant un vérin hydraulique (12) afin d'ajuster
un angle de l'aileron par rapport au corps de navire,
caractérisé en ce que le stabilisateur à aileron comporte :
une section de détection de pression (16a, 16b) qui détecte une pression dans le vérin
hydraulique ;
une section de calcul de couple (27) qui calcule un couple de l'aileron ;
une section d'estimation d'angle d'aileron (24) qui estime un angle de l'aileron par
rapport à un écoulement d'eau de mer sur la base du couple calculé ; et
une section de génération de commande (23) qui génère une valeur de commande d'angle
d'aileron (θ3) afin de faire correspondre l'angle d'aileron estimé (θ2') avec un angle
cible (θ1) de façon à contrecarrer le mouvement de basculement du corps de navire,
et le dispositif d'entraînement d'aileron (12) entraîne l'aileron sur la base de la
valeur de commande d'angle d'aileron.
2. Stabilisateur à aileron selon la revendication 1, comportant en outre une section
de détection d'angle d'aileron qui détecte un angle de l'aileron par rapport au corps
de navire, et
dans le cas où un cycle de mouvement de basculement du corps de navire est inférieur
ou égal à une valeur de seuil prédéterminée préétablie, la section de génération de
commande génère une valeur de commande d'angle d'aileron afin de faire correspondre
l'angle d'aileron détecté par la section de détection d'angle d'aileron avec l'angle
cible.
3. Stabilisateur à aileron selon la revendication 2, dans lequel la section de détection
de pression comporte :
un capteur de pression qui détecte respectivement des pressions dans une chambre de
cylindre supérieure et une chambre de cylindre inférieure du vérin hydraulique ; et
une section de suppression de bruit qui élimine une composante de bruit contenue dans
une valeur de détection détectée par le capteur de pression,
et la valeur de seuil prédéterminée est déterminée sur la base de la performance de
la section de suppression de bruit.
4. Stabilisateur à aileron selon la revendication 1 comportant en outre :
une section de détection d'angle d'aileron qui détecte un angle de l'aileron par rapport
au corps de navire ; et
une section de calcul de différence qui trouve une différence entre un angle de l'aileron
par rapport à un écoulement d'eau de mer estimé par la section d'estimation d'angle
d'aileron et un angle de l'aileron par rapport au corps de navire détecté par la section
de détection d'angle d'aileron,
et dans un cas où la différence est supérieure ou égale à une valeur prédéterminée
préétablie, la section de génération de commande génère une valeur de commande d'angle
d'aileron afin de faire correspondre l'angle d'aileron par rapport au corps de navire
détecté par la section de détection d'angle d'aileron avec l'angle cible.
5. Procédé de commande pour un stabilisateur à aileron pour un navire qui comporte un
aileron fixé sur un corps de navire afin de réduire un mouvement de basculement du
corps de navire, et un dispositif d'entraînement d'aileron ayant un vérin hydraulique
destiné à ajuster un angle de l'aileron par rapport au corps de navire, dans lequel
le procédé de commande comporte :
une étape de calcul d'un couple de l'aileron basé sur une pression du cylindre hydraulique
;
une étape d'estimation d'un angle de l'aileron par rapport à un écoulement d'eau de
mer sur la base du couple calculé ;
une étape de génération d'une valeur de commande d'angle d'aileron afin de faire correspondre
l'angle d'aileron estimé avec un angle cible de façon à contrecarrer le mouvement
de basculement du corps de navire ; et
une étape de commande du dispositif d'entraînement d'aileron sur la base de la valeur
de commande d'angle d'aileron.
6. Programme de commande pour un stabilisateur à aileron pour un navire qui comporte
un aileron fixé sur un corps de navire afin de réduire un mouvement de basculement
du corps de navire, et un dispositif d'entraînement d'aileron ayant un vérin hydraulique
destiné à ajuster un angle de l'aileron par rapport au corps de navire, pour l'exécution
sur un ordinateur de :
une étape de calcul d'un couple de l'aileron sur la base d'une pression du cylindre
hydraulique ;
une étape d'estimation d'un angle de l'aileron par rapport à un écoulement d'eau de
mer sur la base du couple calculé ;
une étape de génération d'une valeur de commande d'angle d'aileron afin de faire correspondre
l'angle d'aileron estimé avec un angle visé de façon à contrecarrer le mouvement de
basculement du corps de navire ; et
une étape de commande du dispositif d'entraînement d'aileron sur la base de la valeur
de commande d'angle d'aileron.