System and method for controlling rolling motion of a marine vessel

Patent metadata

Field	Value
Publication number	US-2016288884-A1
Application number	US-201615077430-A
Country	US
Kind code	A1
Filing date	Mar 22, 2016
Priority date	Apr 2, 2015
Publication date	Oct 6, 2016
Grant date	—

Abstract

A system for countering the rolling motion of a marine vessel, includes one or more sensors adapted to characterise a sea condition approaching the vessel, one or more control systems, a computer, and one or more active stabilisers. The computer is adapted to receive the characterised sea condition data, is further adapted to generate one or more control signals in dependence on the characterised sea condition data, and is still further adapted to transmit the or each control signal to the or each control system. The or each control system is in turn adapted to actuate the or each active stabiliser in response to receipt of the or each control signal, to counter the rolling motion of the marine vessel.

First claim

1 . A system for countering the rolling motion of a marine vessel, the motion control system comprising:
one or more sensors adapted to characterise a sea condition approaching the vessel; one or more control systems; a computer, the computer being adapted to receive the characterised sea condition data; the computer being further adapted to generate one or more control signals in dependence on the characterised sea condition data; the computer being still further adapted to transmit the or each control signal to the or each control system; and one or more active stabilisers, wherein the or each control system is adapted to actuate the or each active stabiliser in response to receipt of the or each control signal, to counter the rolling motion of the marine vessel.

2 . The system as claimed in claim 1 , wherein the at least one sensor characterises approaching waves by determining one or more parameters selected from the group comprising wave height, wave length, wave surface slope, the wave roughness, and the wave grouping.

3 . The system as claimed in claim 1 , wherein the or each active stabiliser is selected from the group comprising rudders, fins, foils and trim tabs, propellers, steerable water jets, internal stabilisers, movable weights, and anti-roll tanks.

4 . The system as claimed in claim 1 , wherein the or each sensor is adapted to collect sea condition data from the marine vessel's far field.

5 . The system as claimed in claim 4 , wherein the marine vessel's far field extends from the vessel for a distance of 1 , 000 m.

6 . A method of countering the rolling motion of a marine vessel, the marine vessel comprising one or more active stabilisers, the method comprising the steps of:
sensing a speed and a heading for the marine vessel relative to the approaching wave; characterising a first surface profile of a wave field approaching the marine vessel, using one or more sensors; predicting a second surface profile of the wave field resulting from the wave field encountering the marine vessel at a chosen time in the future, using the characterised first surface profile, together with the vessel's speed and heading; computing one or more control signals, using the predicted second surface profile; and transmitting the one or more control signals to the one or more active stabilisers, to cause the one or more active stabilisers to apply a heeling moment to the marine vessel to counter the roll moment produced by the impingement of the wave field on the marine vessel.

7 . The method as claimed in claim 6 , wherein the or each active stabiliser is selected from the group comprising rudders, fins, foils and trim tabs, propellers, steerable water jets, internal stabilisers, movable weights, and anti-roll tanks.

8 . The method as claimed in claim 6 , wherein the step of:
characterising a first surface profile of a wave field approaching the marine vessel, using one or more sensors, comprises the step of: measuring characteristics of a wave field approaching the marine vessel to thereby generate a first sea surface profile.

9 . The method as claimed in claim 8 , wherein the characteristics are selected from the group comprising wave height, wave length, wave surface slope, wave roughness and wave grouping.

10 . The method as claimed in claim 6 , wherein the step of:
predicting a second surface profile of the wave field corresponding to a future impingement of the wave field on the marine vessel, using the characterised first surface profile, together with the vessel's speed and heading, comprises the steps of: predicting a first impingement time being the time at which the approaching wave field will impinge on the marine vessel; applying a harmonic analysis technique to decompose the first surface profile into constituent simple sinusoidal wave components of known amplitude and length; predicting the wave celerity of the constituent sine waves; determining the relative phase shift of the sinusoidal wave components; and phase shift the component waves for the future impingement of the wave field on the marine vessel for the time involved and then recombine the constituent wave components in their shifted relationship to derive a new wave slope corresponding to the future impingement of the wave field on the marine vessel.

11 . The method as claimed in claim 10 , wherein, for a sea depth being greater than half of the wave length, the wave celerity of the constituent sine waves is predicted by:

(

celerity

d
>

L
2

=

gL

2

π

)

where:
g=acceleration due to gravity (m/s 2 );
L=wave length (m); and
d=sea depth (m).

12 . The method as claimed in claim 10 , wherein, for a sea depth being greater than 0.05 times the wave length but less than half of the wave length, the wave celerity of the constituent sine waves is predicted by:

(

celerity

L
20

<
d
<

L
2

=

gL

2

π



tanh


(

2

π


d
L

)

)

where:
g=acceleration due to gravity (m/s 2 );
L=wave length (m); and
d=sea depth (m).

13 . The method as claimed in claim 6 , wherein the step of:
the control system automatically acting on at least one of the one or more control signals in advance of the predicted sea surface profile to actuate one or more active stabilisers to thereby control the rolling motion of the marine vessel, comprises the step of: calculating the degree of actuation required to be fed into the active stabiliser at what instant so that a stabilisation effort is deployed as the marine vessel encounters the sea condition corresponding to the predicted sea surface profile, so as to prevent roll of the marine vessel.

14 . The method as claimed in claim 6 , wherein the step of:
determining a predicted sea surface profile using the detected actual sea surface profile, comprises the additional init

Assignees

• Rolls Royce Plc

Inventors

• Edmunds Colin R

Classifications

• B63B39/005 Primary

  Equipment to decrease ship's vibrations produced externally to the ship, e.g. wave-induced vibrations (propulsion mountings for anti-vibration purposes B63H21/30; vibration dampers, suppression of vibration in systems F16F) · CPC title

• B63B39/00

  Equipment to decrease pitch, roll, or like unwanted vessel movements; Apparatus for indicating vessel attitude {(for amphibious vehicles B60F3/0038)} · CPC title

• G08G5/54

  for approach or landing · CPC title

• G05D1/0875 Primary

  specially adapted to water vehicles · CPC title

• G08G5/02

  Physics · mapped topic