WO2017095235A1

WO2017095235A1 - Dynamic control configuration system and method

Info

Publication number: WO2017095235A1
Application number: PCT/NZ2016/050186
Authority: WO
Inventors: John Robert Borrett; Michael Patrick Meade
Original assignee: Cwf Hamilton & Co Ltd
Priority date: 2015-11-30
Filing date: 2016-11-28
Publication date: 2017-06-08
Also published as: AU2015101731A4

Abstract

A method for configuring a closed loop manoeuvring and propulsion control system of a marine vessel is provided. The manoeuvring/propulsion system comprises at least one waterjet and at least one engine, the manoeuvring/propulsion system configured to provide at least one thrust vector that acts to move the vessel along an axis, or respective axes. The method comprises at least one controller generating at least one thrust demand operable to cause the manoeuvring/propulsion system to generate the at least one thrust vector that causes the vessel to move along an axis; determining the actual thrust generated by the manoeuvring/propulsion system and/or measuring an actual velocity of the vessel in response to the actual thrust vector; determining, by applying at least one mathematical model, a predicted thrust and/or predicted velocity of the vessel in response to the thrust demand and/or the actual thrust vector, the at least one mathematical model having at least one parameter; determining an output error at least partly from at least one difference between the actual thrust and/or the actual velocity of the vessel and the predicted thrust and/or predicted velocity of the vessel; modifying the at least one parameter, or at least one of the parameters, so as to minimise the output error; on detecting a minimal output error, determining the value of the at least one parameter, or at least one of the parameters; and determining at least one controller gain associated to the at least one controller based at least partly on the at least one determined parameter value, or at least one of the determined parameter values. Also provided are configuration systems, computer executable instructions, control systems and configuration devices.

Description

DYNAMIC CONTROL CONFIGURATION SYSTEM AND METHOD

FIELD OF INVENTION

The invention relates generally to a closed loop manoeuvring and propulsion control system of a marine vessel. More particularly the invention relates to techniques and apparatus for configuring a closed loop manoeuvring and propulsion control system.

BACKGROUND OF THE INVENTION

Some marine vessels are propelled by one or more water jets and one or more engines. Such vessels typically include one or more control levers to control the position of the water jet reverse duct(s) and the throttle setting of the engine(s) driving the water jet unit(s). Also provided is a helm wheel that controls the position of the steering

deflector(s) or nozzle(s) of the waterjet unit(s).

More recently, joystick control devices have been incorporated into the control systems of water jet vessels to provide an alternative control means particularly for low speed manoeuvring. US patent 6,865,996, for example, describes a control system for low speed manoeuvring which enables a helmsperson to utilise a dual-axis joystick in addition to the helm wheel. US patent 6,386,930 describes a low speed manoeuvring control system which comprises a three-axis joystick. Such control systems are open loop control systems in which the helmsperson or operator 'closes the loop' by

commanding a desired vessel movement, observing actual vessel movement, and further moving the control device(s) to perfect the vessel movement.

Some marine vessels include a manoeuvring and propulsion control system or systems, that incorporate closed loop control of the vessel's dynamic response. Generally such a closed loop control system incorporates a controller, such as a Proportional + Integral + Derivative (PID) controller. The PID controller operates to minimise an error signal, the error being calculated as the difference between a demanded and a measured parameter. The controller continuously operates to minimise the error, to keep the parameter being controlled as close as possible to the demanded value.

International patent application WO 2007/035119, for example, discloses a steering system for a marine vessel which includes a rate sensor and a control system. The rate sensor is configured to generate a turn rate signal indicative of the vessel actual turn rate. The control system is configured to receive vessel actual and helmsperson demanded turn rate signals. The control system is further configured to control the steering devices of the vessel to turn the marine vessel so as to minimise any difference between the signals. This closed loop control system avoids the need for the helmsperson to constantly adjust the steering input device in order to maintain either a straight course or a particular desired rate of turn.

Also international patent application WO 2007/142537 discloses a dynamic control system for a water jet driven marine vessel for maintaining vessel position or velocity when in a dynamic control mode. This system comprises a position or velocity indicator to indicate vessel position or velocity or position or velocity deviations, a heading indicator to indicate vessel heading or yaw rate or deviations, and a controller arranged to operate the waterjet unit(s) of the vessel to maintain the demanded vessel position or velocity and heading or yaw rate.

In the case of a station keeping system, the operator sets certain heading and position values (the set points) that the vessel is required to maintain. The controller operates so as to cause the actual heading and position of the vessel as measured by a compass (or other device capable of sensing true heading) and a GPS unit (or other device capable of sensing true position) to match the set point heading and position values. It does this by continually calculating and updating demands to the vessel thruster system, the demands being a function of the error between the set point(s) and the actual vessel heading and position.

Marine vessels differ greatly in their dynamic response according to their size, type, weight, and hull geometry etc. The response will also vary depending on the response characteristics of the hydraulic activation subsystems that move the water jet steering and reverse deflectors, and of the engine to changes in thrust demand. It is therefore necessary to tune or configure the controller to suit each vessel's dynamic

characteristics. For example, if a heading controller uses PID control, this means that three gain values have to be determined, one for each of the proportional, integral and derivative terms. The tuning process must optimise the three gain terms in order to achieve accurate and responsive control of the vessel without any instability of the control loop.

Where closed loop control is being used in a station keeping system, the controller has to operate on three separate control loops to maintain the vessel's surge position, sway position and heading at the desired set points. If PID controllers are used in this type of system, a total of nine gain terms have to be tuned for each specific vessel.

Controller tuning may be done by various analytical methods, but these invariably require a detailed mathematical model of the 'plant' being controlled. In particular, a set of parameters that describe the vessel dynamics in the axes of interest are needed. This information is rarely available for a particular vessel design and this invariably means that controller tuning has to be done on a 'trial and error' basis.

A skilled person with experience in different vessel types and their dynamic

characteristics can generally tune a controller adequately by trial and error. However, as well as requiring specialist skills, this approach is time consuming, and often results in sub-optimal control of the vessel.

Furthermore, after initial set up the closed loop control system may require re-set up, configuration, or calibration from time to time during its life.

It is an object of preferred embodiments of the present invention to address some of the aforementioned disadvantages. An additional or alternative object is to at least provide the public with a useful choice.

SUMMARY OF THE INVENTION

In one aspect the invention comprises a method for configuring a closed loop

manoeuvring and propulsion control system of a marine vessel, the

manoeuvring/propulsion system comprising at least one waterjet and at least one engine, the manoeuvring/propulsion system configured to provide at least one thrust vector that acts to move the vessel along an axis, or respective axes, the method comprising : at least one controller generating at least one thrust demand operable to cause the manoeuvring/propulsion system to generate the at least one thrust vector that causes the vessel to move along an axis; determining the actual thrust generated by the manoeuvring/propulsion system and/or measuring an actual velocity of the vessel in response to the actual thrust vector; determining, by applying at least one mathematical model, a predicted thrust and/or predicted velocity of the vessel in response to the thrust demand and/or the actual thrust vector, the at least one mathematical model having at least one parameter; determining an output error at least partly from at least one difference between the actual thrust and/or the actual velocity of the vessel and the predicted thrust and/or predicted velocity of the vessel; modifying the at least one parameter, or at least one of the parameters, so as to minimise the output error; on detecting a minimal output error, determining the value of the at least one parameter, or at least one of the parameters; and determining at least one controller gain associated to the at least one controller based at least partly on the at least one determined parameter value, or at least one of the determined parameter values.

The term 'comprising' as used in this specification means 'consisting at least in part of. When interpreting each statement in this specification that includes the term 'comprising', features other than that or those prefaced by the term may also be present. Related terms such as 'comprise' and 'comprises' are to be interpreted in the same manner. Preferably the at least one mathematical model comprises a thrust system modeller.

Preferably the thrust system modeller has at least one parameter selected from a model gain, a model natural frequency, a model damping factor, a model time delay. Preferably the method further comprises determining a value for one or more of the model gain, the model natural frequency, the model damping factor, the model time delay.

Preferably the at least one mathematical model comprises a vessel system modeller.

Preferably the vessel system modeller has at least one parameter selected from a model gain, a model time constant.

Preferably the method further comprises determining a value for one or more of the model gain and the model time constant.

Preferably the method comprises applying at least two mathematical models, the mathematical models comprising a thrust system modeller and a vessel system modeller. Preferably the method further comprises the at least one controller generating a plurality of thrust demands intended to cause the vessel to perform a sequence of predefined movements.

Preferably the plurality of thrust demands comprises a time varying signal that is recorded for comparison against the movement of the vessel, the time varying signal reversing direction when the vessel reaches a predefined velocity or position threshold.

Preferably the plurality of thrust demands comprises a step input. Preferably the plurality of thrust demands comprises a sine wave.

Preferably the plurality of thrust demands comprises a square wave having variable amplitudes and/or periods. Preferably the method further comprises a demand allocator generating a thrust vector at least partly from the thrust demand, the demand allocator generating one or more of: steering demand(s) for the or at least one of the waterjets, reverse demand(s) for the or at least one of the waterjets, RPM demand(s) for the or at least one of the engines.

Preferably determining the actual thrust generated by the manoeuvring/propulsion system comprises measuring one or more of: steering nozzle position for the or at least one of the waterjets, reverse duct position for the or at least one of the waterjets, RPM of the or at least one of the engines.

In another aspect the invention comprises a configuration system for configuring a closed loop manoeuvring and propulsion control system of a marine vessel, the

manoeuvring/propulsion system comprising at least one waterjet and at least one engine, the manoeuvring/propulsion system configured to provide at least one thrust vector that acts to move the vessel along an axis, or respective axes, the system comprising : at least one controller configured to generate at least one thrust demand operable to cause the manoeuvring/propulsion system to generate the at least one thrust vector that causes the vessel to move along an axis; an actual thrust determiner component configured to determine the actual thrust generated by the

manoeuvring/propulsion system and/or an actual velocity measurer component configured to measure an actual velocity of the vessel in response to the actual thrust vector; a predicted thrust component configured to determine, by applying at least one mathematical model, a predicted thrust and/or a predicted velocity component configured to determine, by applying at least one mathematical model, a predicted velocity of the vessel in response to the thrust demand and/or the actual thrust vector, the at least one mathematical model having at least one parameter; a minimiser component configured to: determine an output error at least partly from at least one difference between the actual thrust and/or the actual velocity of the vessel and the predicted thrust and/or predicted velocity of the vessel, modify the at least one parameter, or at least one of the parameters, so as to minimise the output error, and on detecting a minimal output error, determining the value of the at least one parameter, or at least one of the parameters; and a controller gain determiner configured to determine at least one controller gain associated to the at least one controller based at least partly on the at least one determined parameter value, or at least one of the determined parameter values.

Preferably the at least one mathematical model comprises a thrust system modeller. Preferably the thrust system modeller has at least one parameter selected from a model gain, a model natural frequency, a model damping factor, a model time delay.

Preferably the predicted thrust component and/or predicted velocity component is configured to determine a value for one or more of the model gain, the model natural frequency, the model damping factor, the model time delay.

Preferably the at least one mathematical model comprises a vessel system modeller. Preferably the vessel system modeller has at least one parameter selected from a model gain, a model time constant.

Preferably the predicted thrust component and/or predicted velocity component is configured to determine a value for one or more of the model gain, the model time constant.

Preferably the predicted thrust component and/or predicted velocity component is configured to apply at least two mathematical models, the mathematical models comprising a thrust system modeller and a vessel system modeller.

Preferably the at least one controller is configured to generate a plurality of thrust demands intended to cause the vessel to perform a sequence of predefined movements.

Preferably the plurality of thrust demands comprises a square wave having variable amplitudes and/or periods. Preferably the configuration system further comprises a demand allocator configured to generate a thrust vector at least partly from the thrust demand, the demand allocator generating one or more of: steering demand(s) for the or at least one of the waterjets, reverse demand(s) for the or at least one of the waterjets, RPM demand(s) for the or at least one of the engines. Preferably the actual thrust determiner component is configured to determine the actual thrust generated by the manoeuvring/propulsion system by measuring one or more of: steering nozzle position for the or at least one of the waterjets, reverse duct position for the or at least one of the waterjets, RPM of the or at least one of the engines.

In a further aspect the invention comprises a computer readable medium on which is stored computer executable instructions that, when executed by a processor, cause the processor to perform a method for configuring a closed loop manoeuvring and propulsion control system of a marine vessel, the manoeuvring/propulsion system comprising at least one waterjet and at least one engine, the manoeuvring/propulsion system configured to provide at least one thrust vector that acts to move the vessel along an axis, or respective axes, the method comprising : at least one controller generating at least one thrust demand operable to cause the manoeuvring/propulsion system to generate the at least one thrust vector that causes the vessel to move along an axis; determining the actual thrust generated by the manoeuvring/propulsion system and/or measuring an actual velocity of the vessel in response to the actual thrust vector;

determining, by applying at least one mathematical model, a predicted thrust and/or predicted velocity of the vessel in response to the thrust demand and/or the actual thrust vector, the at least one mathematical model having at least one parameter; determining an output error at least partly from at least one difference between the actual thrust and/or the actual velocity of the vessel and the predicted thrust and/or predicted velocity of the vessel; modifying the at least one parameter, or at least one of the parameters, so as to minimise the output error; on detecting a minimal output error, determining the value of the at least one parameter, or at least one of the parameters; and determining at least one controller gain associated to the at least one controller based at least partly on the at least one determined parameter value, or at least one of the determined parameter values. Preferably the at least one mathematical model comprises a thrust system modeller.

Preferably the at least one mathematical model comprises a vessel system modeller. Preferably the vessel system modeller has at least one parameter selected from a model gain, a model time constant. Preferably the method further comprises determining a value for one or more of the model gain and the model time constant.

Preferably the method further comprises applying at least two mathematical models, the mathematical models comprising a thrust system modeller and a vessel system modeller.

Preferably the method further comprises the at least one controller generating a plurality of thrust demands intended to cause the vessel to perform a sequence of predefined movements. Preferably the plurality of thrust demands comprises a time varying signal that is recorded for comparison against the movement of the vessel, the time varying signal reversing direction when the vessel reaches a predefined velocity or position threshold.

Preferably the plurality of thrust demands comprises a step input.

Preferably the plurality of thrust demands comprises a sine wave.

Preferably the plurality of thrust demands comprises a square wave having variable amplitudes and/or periods.

Preferably the method further comprises a demand allocator generating a thrust vector at least partly from the thrust demand, the demand allocator generating one or more of: steering demand(s) for the or at least one of the waterjets, reverse demand(s) for the or at least one of the waterjets, RPM demand(s) for the or at least one of the engines.

In a further aspect the invention comprises a closed loop manoeuvring and propulsion control system of a marine vessel, the manoeuvring/propulsion system comprising at least one waterjet and at least one engine, the manoeuvring/propulsion system configured to provide at least one thrust vector that acts to move the vessel along an axis, or respective axes, the system having at least one controller configured to generate at least one thrust demand operable to cause the manoeuvring/propulsion system to generate the at least one thrust vector that causes the vessel to move along an axis, the manoeuvring/propulsion system including a configuration device, the device comprising : an actual thrust determiner component configured to determine the actual thrust generated by the manoeuvring/propulsion system and/or an actual velocity measurer component configured to measure an actual velocity of the vessel in response to the actual thrust vector; a predicted thrust component configured to determine, by applying at least one mathematical model, a predicted thrust and/or a predicted velocity component configured to determine, by applying at least one mathematical model, a predicted velocity of the vessel in response to the thrust demand and/or the actual thrust vector, the at least one mathematical model having at least one parameter; a minimiser component configured to: determine an output error at least partly from at least one difference between the actual thrust and/or the actual velocity of the vessel and the predicted thrust and/or predicted velocity of the vessel, modify the at least one parameter, or at least one of the parameters, so as to minimise the output error, and on detecting a minimal output error, determining the value of the at least one parameter, or at least one of the parameters; and a controller gain determiner configured to determine at least one controller gain associated to the at least one controller based at least partly on the at least one determined parameter value, or at least one of the determined parameter values.

Preferably the predicted thrust component and/or predicted velocity component is configured to determine a value for one or more of the model gain, the model time constant. Preferably the predicted thrust component and/or predicted velocity component is configured to apply at least two mathematical models, the mathematical models comprising a thrust system modeller and a vessel system modeller.

Preferably the plurality of thrust demands comprises a square wave having variable amplitudes and/or periods. Preferably the system further comprises a demand allocator configured to generate a thrust vector at least partly from the thrust demand, the demand allocator generating one or more of: steering demand(s) for the or at least one of the waterjets, reverse demand(s) for the or at least one of the waterjets, RPM demand(s) for the or at least one of the engines.

Preferably the actual thrust determiner component is configured to determine the actual thrust generated by the manoeuvring/propulsion system by measuring one or more of: steering nozzle position for the or at least one of the waterjets, reverse duct position for the or at least one of the waterjets, RPM of the or at least one of the engines.

In a further aspect the invention comprises a configuration device adapted to configure a closed loop manoeuvring and propulsion control system of a marine vessel, the manoeuvring/propulsion system comprising at least one waterjet and at least one engine, the manoeuvring/propulsion system configured to provide at least one thrust vector that acts to move the vessel along an axis, or respective axes, the system having at least one controller configured to generate at least one thrust demand operable to cause the manoeuvring/propulsion system to generate the at least one thrust vector that causes the vessel to move along an axis, the configuration device comprising : an actual thrust determiner component configured to determine the actual thrust generated by the manoeuvring/propulsion system and/or an actual velocity measurer component configured to measure an actual velocity of the vessel in response to the actual thrust vector; a predicted thrust component configured to determine, by applying at least one mathematical model, a predicted thrust and/or a predicted velocity component configured to determine, by applying at least one mathematical model, a predicted velocity of the vessel in response to the thrust demand and/or the actual thrust vector, the at least one mathematical model having at least one parameter; a minimiser component configured to: determine an output error at least partly from at least one difference between the actual thrust and/or the actual velocity of the vessel and the predicted thrust and/or predicted velocity of the vessel, modify the at least one parameter, or at least one of the parameters, so as to minimise the output error, and on detecting a minimal output error, determining the value of the at least one parameter, or at least one of the parameters; and a controller gain determiner configured to determine at least one controller gain associated to the at least one controller based at least partly on the at least one determined parameter value, or at least one of the determined parameter values.

Preferably the predicted thrust component and/or the predicted velocity component is configured to determine a value for one or more of the model gain, the model natural frequency, the model damping factor, the model time delay.

Preferably the predicted thrust component and/or predicted velocity component is configured to apply at least two mathematical models, the mathematical models comprising a thrust system modeller and a vessel system modeller. Preferably the at least one controller is configured to generate a plurality of thrust demands intended to cause the vessel to perform a sequence of predefined movements.

Preferably the plurality of thrust demands comprises a square wave having variable amplitudes and/or periods. Preferably the configuration device further comprises a demand allocator configured to generate a thrust vector at least partly from the thrust demand, the demand allocator generating one or more of: steering demand(s) for the or at least one of the waterjets, reverse demand(s) for the or at least one of the waterjets, RPM demand(s) for the or at least one of the engines.

The term 'computer-readable medium' should be taken to include a single medium or multiple media. Examples of multiple media include a centralised or distributed database and/or associated caches. These multiple media store the one or more sets of computer executable instructions. The term 'computer readable medium' should also be taken to include any medium that is capable of storing, encoding or carrying a set of instructions for execution by a processor and that cause the processor to perform any one or more of the methods described above. The computer-readable medium is also capable of storing, encoding or carrying data structures used by or associated with these sets of

instructions. The term 'computer-readable medium' includes solid-state memories, optical media and magnetic media.

The terms 'component', 'module', 'system', 'interface', and/or the like are generally intended to refer to a computer-related entity, either hardware, a combination of hardware and software, software, or software in execution. For example, a component may be, but is not limited to being, a process running on a processor, a processor, an object, an executable, a thread of execution, a program, and/or a computer. By way of illustration, both an application running on a controller and the controller can be a component. One or more components may reside within a process and/or thread of execution and a component may be localized on one computer and/or distributed between two or more computers.

The term 'connected to', when used in relation to data transfer, includes all direct or indirect types of communication, including wired and wireless, via a cellular network, via a data bus, or any other computer structure. It is envisaged that they may be

intervening elements between the connected integers. Variants such as 'in

communication with', 'joined to', and 'attached to' are to be interpreted in a similar manner. Related terms such as 'connecting' and 'in connection with' are to be interpreted in the same manner.

The invention in one aspect comprises several steps. The relation of one or more of such steps with respect to each of the others, the apparatus embodying features of

construction, and combinations of elements and arrangement of parts that are adapted to affect such steps, are all exemplified in the following detailed disclosure.

This invention may also be said broadly to consist in the parts, elements and features referred to or indicated in the specification of the application, individually or collectively, and any or all combinations of any two or more said parts, elements or features, and where specific integers are mentioned herein which have known equivalents in the art to which this invention relates, such known equivalents are deemed to be incorporated herein as if individually set forth.

As used herein, \s)' following a noun means the plural and/or singular forms of the noun. As used herein, the term 'and/or' means 'and' or 'or' or both.

It is intended that reference to a range of numbers disclosed herein (for example, 1 to 10) also incorporates reference to all rational numbers within that range (for example, 1, 1.1, 2, 3, 3.9, 4, 5, 6, 6.5, 7, 8, 9, and 10) and also any range of rational numbers within that range (for example, 2 to 8, 1.5 to 5.5, and 3.1 to 4.7) and, therefore, all sub- ranges of all ranges expressly disclosed herein are hereby expressly disclosed. These are only examples of what is specifically intended and all possible combinations of numerical values between the lowest value and the highest value enumerated are to be considered to be expressly stated in this application in a similar manner. In this specification where reference has been made to patent specifications, other external documents, or other sources of information, this is generally for the purpose of providing a context for discussing the features of the invention. Unless specifically stated otherwise, reference to such external documents or such sources of information is not to be construed as an admission that such documents or such sources of information, in any jurisdiction, are prior art or form part of the common general knowledge in the art.

Although the present invention is broadly as defined above, those persons skilled in the art will appreciate that the invention is not limited thereto and that the invention also includes embodiments of which the following description gives examples.

BRIEF DESCRIPTION OF THE DRAWINGS

Preferred forms of the method and system for configuring a closed loop manoeuvring and propulsion control system will now be described by way of example only with reference to the accompanying figures in which :

Figure 1 shows a schematic arrangement of one embodiment of a configurable marine vessel; Figure 2 shows an alternative embodiment of a marine vessel control system to that shown in Figure 1 ;

Figure 3 shows a simplified form of the control system of figure 1 and figure 2; Figure 4 shows an example configuration process;

Figure 5 shows an example of recorded data from a vessel system identification test in a surge axis; Figure 6 shows a complete model of the control system for one axis; and

Figure 7 shows an example of a user interface associated to the configuration tool implemented on a computing device. DETAILED DESCRIPTION

Figure 1 shows a schematic arrangement of one embodiment of a marine vessel that is configurable in accordance with one aspect of the invention. The marine vessel is representative of a type of vessel that is propelled with two waterjet units at the stern of the vessel, known as a twin waterjet vessel. The techniques described below for configuring a twin waterjet vessel may also be used on waterjet vessels propelled by more than two waterjet units, such as three or four waterjet units, or single or multiple waterjets in combination with a bow thruster, for example. The vessel includes a controller 100, such as a microprocessor, microcontroller, programmable logic controller (PLC) or the like programmed to receive and process data so as to dynamically control the vessel when the dynamic control mode is enabled.

The controller 100 controls port and starboard waterjet units 102 that are the primary manoeuvring/propulsion systems for the vessel. Where more than two waterjet units are provided as referred to previously, the controller 100 is adapted to provide dynamic control to at least one port waterjet unit and one starboard waterjet unit.

One or both waterjet units 102 comprise(s) a housing containing a pumping unit 104 driven by an engine 106 through a driveshaft 108. Each waterjet unit also includes a steering deflector 110 and a reverse duct 112. In the form illustrated, each reverse duct 112 is of a type that features split passages to improve reverse thrust and

manoeverability. The split-passage reverse duct 112 also affects the steering thrust to port and starboard when the duct is lowered into the jet stream. The steering deflectors 110 pivot about generally vertical axes 114 while the reverse ducts 112 pivot about generally horizontal axes 116, independently of the steering deflectors.

The engine throttle, steering deflector and reverse duct of one or both units 102 are actuated by signals received from the actuation modules 118 and 120 through control input ports 122, 124 and 126 respectively. The actuation modules 118 and 120 are in turn controlled by the controller 100.

The controller 100 receives a plurality of inputs to effect vessel control. One input comes from one or more vessel control devices 128, such as one or more joysticks, helm controls, throttle levers or the like. The vessel control device(s) 128 is used by a helmsperson to manually operate the vessel.

The controller 100 optionally also receives input from a dynamic control input means 130 which is operated to enable a dynamic control mode. Examples include one or more buttons, switches, keypads or the like. The dynamic control input device 130 is used by the helmsperson to enable a dynamic control mode, including or specifically a dynamic positioning mode in which the controller controls the waterjet units of the vessel to maintain the vessel position and vessel heading, and/or a dynamic velocity mode in which the controller controls the waterjet units of the vessel to maintain vessel velocity and yaw rate, and/or any other desired dynamic control.

The controller 100 has inputs indicative of the vessel position and vessel heading and/or other applicable vessel parameters. The vessel position and vessel heading are used by the controller 100 to maintain the vessel at a desired position and desired heading (herein generally referred to as a commanded vessel position and/or heading), but also to set a desired position and desired heading. Vessel position is determined via position indicator 132. Absolute vessel ground position may be indicated via a satellite-based positioning system such as GPS or DGPS, in which case the position indicator 132 will be a GPS or DGPS unit. GPS provides data relating to earth-referenced positions in terms of latitude and longitude. GPS may be used in its standard form or in DGPS form.

Alternatively, the position indicator 132 may indicate the vessel position relative to an initial vessel reference position via one or more sensors such as accelerometers configured to determine vessel motion relative to an initial position. An electronic circuit receives signals representing vessel acceleration from the

accelerometer(s), and integrates the signals to obtain signals representative of vessel position. Double integration of an acceleration signal produces a position signal. In an embodiment, the outputs of a plurality of sensors are processed (for example after complementary filtering) to improve the indication of position or position deviations.

In an embodiment the position indicator 132 indicates the vessel position relative to a stationary or moving object, such as for example relative to a dock or berth or relative to a moving or stationary surface or submarine vessel. In an embodiment the position indicator comprises a short range radar system or any other system that indicates range and bearing from the vessel to the target object whether stationary or moving, such as an acoustic or laser-based range finding system.

In dynamic control with respect to moving objects, the relative positions and/or velocities between a moving object and the vessel being controlled are obtained. In this way, the controlled vessel may be controlled to maintain a rate or positional 'relationship' with the moving object. Example applications for dynamic position control with respect to moving objects include maintaining a given range and bearing from another vessel or an underwater remotely-operated-vehicle, or manoeuvring near a vessel that is drifting. Dynamic control with respect to moving objects may also be used to maintain vessels in a position and/or velocity relationship in pair trawling, where two or more vessels cooperatively pull a net.

The vessel heading is determined using heading indicator 134 that provides the controller 100 with vessel heading data. In an embodiment, heading indicator 134 comprises a GPS compass, fluxgate compass, or a gyro compass for example, that indicates absolute vessel heading.

Alternatively, in an embodiment the heading indicating means indicates the vessel heading relative to an initial vessel reference heading via one or more yaw rate sensors, such as a rate gyro or other sensor device(s) arranged to determine a relative change in vessel heading. Also, the heading indicator in an embodiment is an indicator already provided for an on-board auto-pilot system for example. When the dynamic positioning is enabled, the controller 100 uses the inputs from position indicator 132 and heading indicator 134 to maintain the vessel in a commanded position and heading. This may be the position and heading of the vessel when the dynamic position system was enabled, or alternatively a different vessel position and heading input by the helmsperson or operator via another input means such as a keypad or other computer system via which another commanded position and heading may be input to the controller 100.

The controller 100 then operates the waterjet units 102 and in particular the engine thrust, steering deflectors, and reverse ducts, in synchronism or differentially, to maintain the commanded vessel position and heading.

In an embodiment, the dynamic positioning functionality works in combination with one or more vessel control device(s) 128 used to normally operate the vessel. In one form, the input means 130 works in combination with a slow velocity maneuvering control device of the vessel, such as a joystick, when the control system is in dynamic positioning mode. For instance, after the dynamic positioning mode is enabled in order to maintain vessel position, the helmsperson may subsequently wish to move the vessel to a different position and/or heading and then maintain the vessel at that new position and/or heading.

While the control system is in dynamic positioning mode the helmsperson may operate a control device such as a joystick to move the vessel and then release the joystick or return the joystick to its neutral position. Return of the joystick to its neutral position may cause re-engaging of dynamic positioning so that the control system again operates to maintain the vessel in the new position and/or heading (until the joystick is moved again, or the dynamic positioning mode is disabled).

Figure 2 shows an alternative embodiment of a marine vessel control system. The system, indicated generally with the arrow 200, includes the following main components:

• One or more control input devices 202, such as a maneuvering joystick

• A controller 204

• The engine and waterjet manoeuvring/propulsion systems 206, 208

• A number of vessel sensors 210, 212, 214, 216

· A system to calculate axis transformations 218.

The control input device(s) 202 are the interface between the helmsperson, and the control system. In an embodiment, devices 202 comprise one or more directional control and steering units. In an embodiment, the control input device(s) 202 provide output signals that represent the following desired movements by the vessel :

• A commanded velocity of the vessel, ahead or astern (surge velocity, u)

• A commanded velocity of the vessel, to port or starboard (sway velocity, v)

• A commanded rate of turn of the vessel about the centre of gravity, in a clockwise or anti-clockwise direction (yaw rate, r)

· A mode input.

In an embodiment, the surge and sway velocity, and the rate of turn is demanded using known input devices such as a helm wheel, a single-axis or multiple-axis joystick, buttons, switches or the like. The input device may also be as described in our international patent application WO 2006/062416. The contents of that specification are incorporated herein in their entirety by way of reference.

In an embodiment, the mode is demanded using one or more buttons, switches or the like to enable or select a mode of operation, as will now be described in detail.

One available mode of operation is a 'manual mode', in which an operator manually through the control system operates the waterjet units and its associated controlling surfaces in a conventional manner. Another available mode of operation is a 'positional mode', where the control system operates the waterjet units and its associated controlling surfaces to dynamically position the vessel. Once this mode is selected, such as by pressing a 'hold' button provided on the input device described in our international patent application WO 2006/062416, the control system enables dynamic positioning. While dynamic positioning is enabled, the position at which the vessel is maintained may be adjusted in one or more of the x, y and z axes by either manipulating the steering control device or other control input device(s). For instance, a vessel may be dynamically positioned 5 metres from a dock before having its position adjusted by increments of 1 metre in the y-axis so as to controllably dock the vessel.

A further available mode of operation is a Vate or velocity mode', where the control system operates the waterjet units and its associated controlling surfaces to dynamically control the velocity of the vessel to be consistent with a desired ground velocity. Once this mode is selected, such as by pressing a dedicated button or by inputting a desired ground velocity, the control system enables dynamic velocity control.

The rate at which the vessel moves in one or more of the x, y and z axes may be adjusted by either manipulating the steering control device or other control input device(s) while dynamic velocity control is enabled. For instance, vessel velocity may be dynamically controlled at 20 knots before coming into a velocity-restricted region, and may be decremented using, for example, a Veduce velocity' button to 10 knots upon entering the velocity-restricted region. In another example, an input control device may be provided to maintain the vessel's current velocity.

A further available mode of operation is a 'slave mode', where the control system operates the waterjet units and its associated controlling surfaces to dynamically position or control the velocity of the vessel based relative to a 'master' object, such as a lead vessel.

In an embodiment, a display means 240 is also provided. The display means 240 allows the displaying of one or more of the following parameters: vessel surge velocity, sway velocity, heading and mode of operation. In an embodiment, the display means 240 displays the measured values of the parameters, the demanded values of the

parameters, or both. In an embodiment, the display means 240 comprises a form of control input device by providing touch-sensitive means on the display means 240 so that a helmsperson may input demands, such as changing velocity, selecting a mode, or selecting a new position, by selectively touching areas of the display means 240. The controller 204 receives the demands from the control input device(s) 202. It also receives feedback signals from the vessel sensors 210, 212, 214 and 216, both directly and in the form of processed data that represent the measured vessel velocities u and v. The primary function of the controller 204 is to calculate the difference between the desired velocities and yaw rate and the measured velocities and yaw rate, and set the demands to the waterjets and engines so that the surge and sway velocity and yaw rate errors are minimized.

The manoeuvring/propulsion system for the port jet is shown in detail in the shaded box 206. The starboard manoeuvring/propulsion system is identical to the port one, and is indicated by the box 208. One or both waterjets has actuators 220 and 222 to move the steering deflector and reverse duct. The magnitude of jet thrust is varied by changing the engine velocity. A steering deflector position controller 226 receives a steering deflector demand signal from the controller 204 and a measured steering deflector position from the position sensor 228. The controller 204 drives the actuator 220 so as to minimize the error between the demanded and measured steering deflector positions. This can be done using a conventional closed loop control system.

A second identical control loop, including a reverse duct position sensor 230 and a reverse duct position controller 232, maintains the position of the reverse duct in response to the demand signal from the controller 204.

The third part of the manoeuvring/propulsion system block is the engine speed control. A demand signal from the controller 204 is fed to the engine control system 224 to set a specific engine speed. This varies the jet shaft rotation speed (in revolutions per minute, or RPM) and hence the magnitude of thrust produced by the waterjet.

The vessel block 234 is representative of the vessel being controlled by the control system. As schematically illustrated, the vessel is acted upon by forces and moments produced by the waterjets, and external disturbances such as wind, waves, tidal flow etc. The waterjet forces and moments must be controlled to counteract the external disturbances and thus maintain the vessel on its desired trajectory as defined by the control input device(s) 202.

The combined effects of the forces and moments acting on the vessel are inputs into the vessel block 234. As a result, the vessel can be controlled to move in a certain way with respect to the surface of the Earth. These movements are represented by the 'Latitude', 'Longitude', 'Heading' and 'Yaw rate' indications shown generally as 235. It should be noted that the indications shown at 235 are not electrical signals that are input into the control system of the present invention. Instead, the indications are representative of the movements, which are sensed by sensors 210 to 216.

The position of the vessel is preferably measured using a high accuracy system such as GPS or differential GPS. As this provides outputs of earth referenced position (latitude and longitude), latitude sensor 210 and longitude sensor 212 of the embodiment shown in figure 2 will be incorporated in the preferred GPS or differential GPS system.

In addition, a heading sensor 214 such as a GPS compass, a gyro compass or fluxgate compass is used, together with a yaw rate sensor 216.

The measured parameters from the sensors above are fed directly to the controller 204 via connections V and P shown in figure 2. As an alternative to GPS and a GPS or other compass, accelerometers and a rate gyro may be used to control the vessel's movements based on an earlier vessel position or velocity. In this alternative form, accelerometers replace latitude and longitude sensors 210 and 212 to provide signals indicating acceleration in the x and y axes, and a rate gyro replaces the heading sensor 214 to provide signals indicating velocity changes in the z axis.

The acceleration signals from the accelerometers are integrated once to produce velocity signals, and are integrated once more to produce position signals. The velocity signals from the rate gyro only need to be integrated once to produce position signals. The velocity and position signals derived from the accelerometers and a rate gyro are then input to the controller 204 via connections V and P as shown in figure 2.

In an embodiment as another alternative to GPS and a GPS or other compass, radar is used to provide relevant input signals to dynamically control the vessel. Radar provides indications of bearing and distance, which may be used to define a location at which the vessel should be dynamically positioned, or an object with respect to which the vessel's velocity should be dynamically controlled. For example, where dynamic positioning is desired with respect to a moving object, such as another vessel, a helmsperson may use radar to indicate or select the moving object that will be the object with respect to which dynamic positioning is carried out.

Persons skilled in the art will appreciate that, where the sensors 210 and 212 are replaced with accelerometers, and sensor 214 is replaced with a rate gyro, the above transformation equations will be adapted to suit the signals generated by the accelerometers and rate gyro. For instance, since the accelerometers produce

acceleration signals, integration rather than differentiation is required to produce the velocity and position signals. Also, the rate gyro produces velocity signals, which will need to be integrated to produce position signals. Some GPS systems provide direct outputs of velocity and where this is available the differentiators are not needed.

When a dynamic velocity control system is enabled, the control input devices 202 set the demanded longitudinal and transverse velocities and yaw rates with respect to the ground. The controller 204 determines the errors between the commanded and measured velocities and yaw rates, and calculates the steering deflector demand and reverse duct positions and engine thrust (or rpm) required to minimize these errors. These newly calculated demands are output to the steering deflector and reverse duct position controllers 226 and 232, and the engine velocity controller 224. The manoeuvring/propulsion system then generates thrust forces and moments that act on the vessel. The thrust forces and moments combine with disturbance forces and moments due to wind, tide etc. which together result in movement of the vessel in a direction that reduces the velocity and yaw rate errors. The motion of the vessel is detected by the sensors 210, 212, 214 and 216 to provide feedback to the controller 204, thus closing the loop.

The above described system can also seamlessly act as a dynamic positioning system to provide dynamic positioning of the vessel. This is done by setting the control input devices to a 'zero' position, where a zero velocity in surge and sway, and a zero turn rate is demanded. This causes the controller 204 to change from a 'rate' control mode, as described earlier, where the control system works to match the rate of movement and rotation to that demanded by the control input device, to a 'positional' control mode.

In one form, when the vessel is brought to a stop, the control system takes a 'snapshot' of the position and heading of the vessel. While the control input devices remain at the zero position, the 'snapshot' position and heading are used as the demand inputs and the system performs positional closed loop control, ensuring that the vessel stays in the 'snapshot' position and at the 'snapshot' heading. In this mode the 'direct' feedback and 'snapshot' signals of latitude, longitude and heading are used to calculate error signals for the positional control. This can be compared to the 'rate' or dynamic velocity control mode, where the processed signals of surge and sway velocity and the direct yaw rate signal are used as the feedback. The system described in figure 2 effectively contains three control loops for maintaining the longitudinal, the transverse and the rotational positions or rates. It is possible for these control loops to be in different modes at any one time. For example, when the vessel is moving with certain surge and sway velocity demands but the yaw rate demand is zero, the surge and sway control loops would be in the 'rate' mode while the yaw control loop would be in the 'positional' mode.

The vessel control features and functionality may be of the type described in WO

2007/035119 or WO 2007/142537. The contents of those specifications are incorporated herein in their entirety by way of reference.

The vessel control systems described above with reference to figure 1 and figure 2 are operable in some embodiments as closed loop manoeuvring and propulsion control systems. Described below are embodiments relating specifically to closed loop manoeuvring and propulsion control systems.

Figure 3 shows a simplified form of the control system of figure 1 and figure 2 as including a thrust system 300 and a vessel system 302. The controller 100 from figure 1 or controller 200 from figure 2 generates a thrust demand 304. The thrust demand is operable to cause the manoeuvring/propulsion system of the vessel to generate a thrust vector that causes the vessel to move along a particular axis.

A demand allocator 306 converts the thrust demand 304 into steering and reverse demands 308 for each waterjet unit 102 and RPM demands 310 for each engine 106. As described above, waterjets 102 have associated actuation modules 118,120. The modules receive the steering and reverse demands 308 and actuate for example the hydraulic cylinders or linear/rotary electric actuators to position 312 the steering nozzle and reverse duct in the demanded positions. At the same time the demand allocator 306 sends a signal to or drives an actuator setting the throttle of the engine 106 requesting a certain engine RPM. The engine 106 adjusts the RPM according to this demand.

The combination of steering nozzle and reverse duct positioning and the speed (RPM at the jet) at which the jet shaft is being driven by the engine result in an actual thrust 314 expressed as a certain thrust vector being produced by each waterjet 102. The combined effect of these thrust vectors act on the vessel 316 to cause the vessel to move at a certain velocity 318. Each waterjet 102 is capable of generating a thrust vector independent of the other jet(s). In an embodiment, there is a gearbox (not shown) included between the engine 106 and the waterjet unit 314 that results in an engine RPM potentially different to a waterjet RPM .

When a certain thrust is demanded by the controller 100 and/or 200, it takes time for the jet hydraulics to move and the engine speed to increase. This results in a delay or lag between the demanded thrust 304 and the actual thrust 314. Similarly, when the actual thrust 314 starts acting on the vessel, it takes time for the vessel to respond because of the vessel's mass and the fluid forces acting in opposition to the vessel velocity.

One technique for determining the best controller settings is to have an accurate knowledge, in the form of a mathematical model, of the dynamic characteristics of both the thrust system 300 and the vessel system 302. As will be describe below, these mathematical models of the thrust system 300 and the vessel system 302 are obtained using a process of system identification.

System identification starts by conducting a test which excites the motion of the plant (in one axis at a time) by varying the input in a defined sequence while measuring the output response.

The preferred input signal is a square wave that reverses direction when the vessel reaches a certain velocity or position threshold, but other types of signal such as a step input, a sine wave (constant or varying frequencies) and a square wave with variable amplitudes and periods may also be used. In an embodiment the input signal comprises a time varying signal that is recorded for comparison against the movement of the vessel. The signal reverses direction when the vessel reaches a predefined velocity or position threshold. Referring to figure 4, a test input 400 is applied to the required section of the plant 402, either the thrust system or the vessel system. This causes the test output data 404 to vary in some way related to the test input. Both the test input and output are recorded as a function of time during the test phase. Where the test input 400 is applied to the thrust system the test output data 404 represents an actual thrust generated by the manoeuvring/propulsion system. Where the test input data 400 is applied to the vessel system the test output represents an actual velocity of the vessel in response to an actual thrust vector. The test input data 400 are also applied to at least one mathematical model 406 of the plant after the test, generating a model output 408. The mathematical model(s) each have at least one parameter. Where the mathematical model 406 represents the thrust system, the model output 408 represents a predicted thrust generated by the

manoeuvring/propulsion system. Where the mathematical model 406 represents the vessel system, the model output 408 represents a predicted velocity of the vessel in response to an actual thrust vector.

After testing, the recorded test output data 404 are compared with the model output data 408 when the model is driven by the recorded test input data . The degree of difference between the test output data 404 and model output data 408 is shown as an output error 410. The output error 410 is determined at least partly from at least one difference between the actual thrust and/or actual velocity of the vessel. The

difference(s) between data 404 and data 408 is representative of how well the

mathematical model(s) 406 match the real plant 402.

The output error 410 is input to a system identification module 412. As will be more particularly described below, module 412 varies or modifies at least one model parameter estimate 414 so as to minimise the output error 410. When minimisation of the output error 410 is achieved, the module 412 determines that the best estimates of the model parameter(s) 414 have been reached .

Following the estimation process it is possible to simulate the model output 408 using the final parameter estimate(s) of the mathematical model to determine how accurately the model represents the real plant.

Figure 5 shows an example of recorded data from a vessel system identification test in a surge axis. In plot 500 a test input 400 in the form of a surge thrust is varied between positive and negative values. In plot 502 a test output 404 in the form of a surge velocity is observed to follow the test input 400 with a delayed response. A model output 408 generated from final model parameter estimates 414 shows close agreement with the plant output.

As will be more particularly described below, the system identification module 412 is configured such that the form of the model is pre-defined but the at least one model parameter estimate 414 is initially unknown. This is referred to as a 'grey box' model. The system identification module 412 includes one or more algorithms such as the integral method, ARX method, and genetic algorithm based methods. To obtain the full mathematical model of the plant dynamics in a given axis, system identification is performed in two stages. A first stage relates to the thrust system. A second stage relates to the vessel system. In an embodiment, the data for both processes is obtained from the same tests on the plant. In an embodiment, the data for both processes is obtained by separate tests.

Thrust system identification

When a certain thrust is demanded by the controller 100 and/or 200, it takes time for the jet hydraulics to move and the engine speed to increase. This results in a delay or lag between the demanded thrust and the actual thrust.

The system identification module 412 determines model parameter estimates 414 of the thrust system. The thrust system has several elements that convert the thrust demand from the controller 100 into an actual thrust at the waterjets 102. The dynamic response of these elements needs to be taken into account together with the vessel characteristics in order to determine the at least one controller gain associated to the controller 100,

200.

In an embodiment a thrust system modeller is an example of a mathematical model 406 of the plant. One example of a transfer function forming at least part of the thrust system modeller is as follows:

where: - fd = thrust demand input (measured from test)

f_a = actual thrust output (measured from test)

k = model gain

co_n = model natural frequency

ζ = model damping factor

τ = model time delay

s = Laplace variable

Parameters k, ω_η, ς and τ are unknown parameters initially. Values for these unknown parameters are obtained by one of the system identification algorithms referred to earlier such as the integral method, ARX method, and genetic algorithm based methods.

It is generally not possible to directly measure the thrust being applied to the vessel. Instead in an embodiment, a method of calculation is used that is based on measuring the steering nozzle and reverse duct positions and the jet shaft speed (RPM) on each waterjet. With these parameters and details of the specific waterjet geometry the resultant thrust vector acting on the vessel is calculated.

Vessel system identification

A system identification test for the vessel requires measurement and recording of the thrust vector or moment being applied to the vessel, and the output velocity (linear or angular) in a particular axis.

A vessel system modeller provides a grey box model for the vessel in a given axis of interest. The vessel system modeller in an embodiment includes a first order system of the following transfer function form: -

where: - f = input thrust (measured from test)

v = output velocity (measured from test)

k = model gain

τ = model time constant

s = Laplace variable

The parameters k and τ are unknown initially. The system identification module 412 obtains values for these parameters. In an embodiment, the dimensional vessel parameters, used in the control design stage are derived as follows: -

Damping coefficient = 1/k

Virtual mass = τ/k

An explanation of the integral system identification method applied to the vessel model set out below by way of example. In general terms, each axis of the vessel model is assumed to be a first order system of the form : - —( Λ ^k

where:-

/= input thrust

v = output velocity

k = model gain

τ = model time constant

s = Laplace variable

Equation 1 can be re-arranged as follows :-

[TS + 1 )

*-!(-»)+*/

T T

Integrating the left hand side w.r.t. time gives :-

The values vo, v(t) and ϊ(ί) are known from the measured data obtained from system identification tests, while τ and A: are unknown constants. Equation 2 can therefore be written as:-

v_m (t) f_m {t)dt

or :-

where f_m and v_m are the measured input and output values over time to - U

Substituting n measured values of time, v and f, into equation 3 yields a matrix system as follows:-

where

and

The matrix values Al and A2 are the cumulative integrals of the output and input measured data which may be calculated numerically using the trapezoidal rule. Equation 4 may then be solved by linear least squares to obtain the parameters ΙΙτ and k/τ.

In an embodiment, the test input 400 comprises measured thrust data. The measured thrust data may be determined from the steering nozzle positions, the reverse duct positions and the jet shaft RPM. This measured thrust data is input to the vessel model 406. The model output 408, typically a velocity, is compared with the measured velocity forming the test output 404. The system identification module 412 determines the damping coefficient and virtual mass parameters so as to achieve the minimum overall error between the model and measured outputs.

In an embodiment, a GPS system measures the linear velocity of the vessel in the surge and sway directions during the test. Alternatively or additionally a sensor such as a rate gyro measures the angular velocity or yaw rate. When the thrust and vessel system identification is complete, a full set of estimated model parameters are available and the control system mathematical model is fully defined. The model is then used to determine the at least one controller gain associated to the controller 100. Control design

The techniques described above are intended to determine parameters for the thrust system modeller and the vessel system modeller so as to define a mathematical model of the complete control loop. In an embodiment the mathematical model is used to determine the optimum controller gains associated to a controller for a particular vessel. One technique involves frequency domain analysis methods.

Figure 6 shows a complete model of the control system for one axis. The thrust system 300 and vessel transfer functions 302 are described above. In an embodiment, the P+I controller 600 has the following transfer function : -

where:

e_v = Velocity error 602

fd = thrust demand 304

proportional gain

integral gain s = Laplace variable

The GPS sensor 604 is assumed to have a transfer function of 1.

In an embodiment, the position gain 606 and the velocity gains k_pr and kpi are obtained as follows:-

1. Define a target gain margin of -8 db at a phase angle of -150 degrees

2. Initialise a gain ratio, km = 0.2

3. Calculate the position gain K_p = 0.4 * km

4. Calculate the velocity proportional gain K_pr = vessel mass parameter * km

5. Calculate the velocity integral gain K_Pi = K_pr * vessel mass parameter/vessel

damping parameter

6. Calculate the gain and phase angle for the open loop system where the position error 608 is the input and the vessel position feedback 610 is the output for frequencies starting at 0.01 rad/s up to the point where the phase lag becomes - 150 degrees

7. At this last point, if the gain value is more negative than the target gain margin, increment the parameter km by 0.01 and repeat from step 3.

8. Exit the loop when the gain value at -150 degree phase angle matches the target gain margin within a defined tolerance

9. The controller gains K_p, K_pr and K_Pi are the final values calculated in steps 3, 4 and

Controller tuning system

In an embodiment the controller 100 generates a plurality of thrust demands. The thrust demands are intended to cause the vessel to perform a sequence of predefined movements for the purpose of system identification.

An example of a sequence comprises a sequence of automated zig zag tests on the vessel for each axis. Other sequences are possible for example time varying signals, periodic and non-periodic signals, sine waves, and square waves as more particularly described above.

The thrust demand, thrust feedback, and vessel velocity or rate of turn from the vessel sensors are recorded. The thrust feedback is preferably calculated from waterjet steering, reverse, and RPM feedback. In an embodiment, three tests on each axis are performed to confirm repeatable results. When the tests are complete, the system identification as described above is used to determine the grey box parameter estimates for one or more of the thrust system modeller and the vessel system modeller. The control design process described above is used to determine the controller gains. In an embodiment, the processing of zigzag test results is provided by computer-executable instructions executing on a computing device.

The computing device includes at least one processor that causes the at least one processor to function as a configuration tool. Examples of computing devices include, but are not limited to, personal computers, server computers, hand-held or laptop devices, mobile devices, multiprocessor systems, consumer electronics, mini-computers, mainframe computers, and distributed computing environments. Examples of mobile devices include mobile phones, personal digital assistants (PDAs), media players, and the like. In an embodiment the sequence of predefined movements is maintained on a memory integrated with, or accessible from, the computing device. The computing device is in turn connectable, directly or indirectly, with the processor 100 and/or 200 in order to facilitate data transfer between the computing device and the processor 100, 200.

Alternatively or additionally the sequence of predefined movements is maintained on a memory or other storage device integrated with, or accessible from, the controller 100 and/or 200.

Figure 7 shows an example of a user interface 700 associated to the configuration tool implemented on a computing device. In an embodiment the configuration tool guides a user through a series of different steps and allows comparisons to be made between similar test results.

The select date box 702 defaults to the present date. It is configured to accept a different date from the user.

The process all button 704 initiates a system identification process described above for the thrust system and the vessel models for all recorded test results. A progress indicator 708 indicates the progress of the calculations. On completion, the plot window 706 shows the results from the thrust identification in an upper panel and the vessel system identification in a lower panel. The data displayed in window 706 facilitates user judgement of the quality of the test data. A score is calculated for each test to indicate how well the model data matches the recorded data, with a score of 100% representing a perfect match. The calculated score is shown in a score box 710. A test results display panel 712 permits a user to review test results. The user selects one of the 'Surge', 'Sway' or 'Yaw' tabs according to the axis of interest and selects a test case in the table. Where there are multiple tests for the same axis, the user determines the preferred result (usually the one with the highest score) and hides the unwanted results by selecting them in the table and pressing the 'Hide Case' button 714. If required, this action can be reversed by pressing the 'Show All' button 716.

A control design panel 718 includes a calculate button. Once the preferred test data has been selected for each axis, pressing the calculate button initiates the control design process for all axes. The Surge, Sway and Yaw boxes are checked when this is complete. At this point the Save All button becomes enabled. Selecting the Save All button 720 causes the controller gains associated to the processor 100 of the control system to be updated in the controller 100. At this point the dynamic position control system is able to operate and is ready for final functional tests.

Final tests on the closed loop control stability and response are carried out by performing an automated position step test in each axis and recording position demand and feedback values. The acceptance of these results is based on the detected overshoot and time to settle for the closed loop system compared to a theoretical 'ideal' response.

In an embodiment, the apparatus and techniques described above provide a method for closed loop control systems, such as station keeping systems for example, by which controller parameters for a particular vessel can be directly determined by calculation following simple on-water tests.

There is a potential to save significant time during the vessel commissioning, produce consistent controller performance, and reduce the requirement for specialist skills. In an embodiment, the configuration is at least partly performed by computer executable instructions on a computing device. A user simply connects the computing device to the controller 100, 200 of a vessel. There is a reduced need for skilled persons with experience in different vessel types.

The foregoing description of the invention includes preferred forms thereof. Modifications may be made thereto without departing from the scope of the invention.

Claims

1. A method for configuring a closed loop manoeuvring and propulsion control system of a marine vessel, the manoeuvring/propulsion system comprising at least one waterjet and at least one engine, the manoeuvring/propulsion system configured to provide at least one thrust vector that acts to move the vessel along an axis, or respective axes, the method comprising :

at least one controller generating at least one thrust demand operable to cause the manoeuvring/propulsion system to generate the at least one thrust vector that causes the vessel to move along an axis;

determining the actual thrust generated by the manoeuvring/propulsion system and/or measuring an actual velocity of the vessel in response to the actual thrust vector; determining, by applying at least one mathematical model, a predicted thrust and/or predicted velocity of the vessel in response to the thrust demand and/or the actual thrust vector, the at least one mathematical model having at least one parameter; determining an output error at least partly from at least one difference between the actual thrust and/or the actual velocity of the vessel and the predicted thrust and/or predicted velocity of the vessel;

modifying the at least one parameter, or at least one of the parameters, so as to minimise the output error;

on detecting a minimal output error, determining the value of the at least one parameter, or at least one of the parameters; and

determining at least one controller gain associated to the at least one controller based at least partly on the at least one determined parameter value, or at least one of the determined parameter values.

2. The method of claim 1 wherein the at least one mathematical model comprises a thrust system modeller.

3. The method of claim 2 wherein the thrust system modeller has at least one parameter selected from a model gain, a model natural frequency, a model damping factor, a model time delay.

4. The method of claim 3 further comprising determining a value for one or more of the model gain, the model natural frequency, the model damping factor, the model time delay.

5. The method of claim 1 wherein the at least one mathematical model comprises a vessel system modeller.

6. The method of claim 5 wherein the vessel system modeller has at least one parameter selected from a model gain, a model time constant.

7. The method of claim 6 further comprising determining a value for one or more of the model gain and the model time constant.

8. The method of claim 1 further comprising applying at least two mathematical models, the mathematical models comprising a thrust system modeller and a vessel system modeller.

9. The method of any one of the preceding claims further comprising the at least one controller generating a plurality of thrust demands intended to cause the vessel to perform a sequence of predefined movements.

10. The method of claim 9 wherein the plurality of thrust demands comprises a time varying signal that is recorded for comparison against the movement of the vessel, the time varying signal reversing direction when the vessel reaches a predefined velocity or position threshold.

11. The method of claim 9 or claim 10 wherein the plurality of thrust demands comprises a step input.

12. The method of claim 9 or claim 10 wherein the plurality of thrust demands comprises a sine wave.

13. The method of claim 9 or claim 10 wherein the plurality of thrust demands comprises a square wave having variable amplitudes and/or periods.

14. The method of any one of the preceding claims further comprising a demand allocator generating a thrust vector at least partly from the thrust demand, the demand allocator generating one or more of: steering demand(s) for the or at least one of the waterjets, reverse demand(s) for the or at least one of the waterjets, RPM demand(s) for the or at least one of the engines.

15. The method of any one of the preceding claims wherein determining the actual thrust generated by the manoeuvring/propulsion system comprises measuring one or more of: steering nozzle position for the or at least one of the waterjets, reverse duct position for the or at least one of the waterjets, RPM of the or at least one of the engines.

16. A configuration system for configuring a closed loop manoeuvring and propulsion control system of a marine vessel, the manoeuvring/propulsion system comprising at least one waterjet and at least one engine, the manoeuvring/propulsion system configured to provide at least one thrust vector that acts to move the vessel along an axis, or respective axes, the system comprising :

at least one controller configured to generate at least one thrust demand operable to cause the manoeuvring/propulsion system to generate the at least one thrust vector that causes the vessel to move along an axis;

an actual thrust determiner component configured to determine the actual thrust generated by the manoeuvring/propulsion system and/or an actual velocity measurer component configured to measure an actual velocity of the vessel in response to the actual thrust vector;

a predicted thrust component configured to determine, by applying at least one mathematical model, a predicted thrust and/or a predicted velocity component configured to determine, by applying at least one mathematical model, a predicted velocity of the vessel in response to the thrust demand and/or the actual thrust vector, the at least one mathematical model having at least one parameter;

a minimiser component configured to:

determine an output error at least partly from at least one difference between the actual thrust and/or the actual velocity of the vessel and the predicted thrust and/or predicted velocity of the vessel,

modify the at least one parameter, or at least one of the parameters, so as to minimise the output error, and

a controller gain determiner configured to determine at least one controller gain associated to the at least one controller based at least partly on the at least one determined parameter value, or at least one of the determined parameter values.

17. The configuration system of claim 16 wherein the at least one mathematical model comprises a thrust system modeller.

18. The configuration system of claim 17 wherein the thrust system modeller has at least one parameter selected from a model gain, a model natural frequency, a model damping factor, a model time delay.

19. The configuration system of claim 18 wherein the predicted thrust component and/or predicted velocity component is configured to determine a value for one or more of the model gain, the model natural frequency, the model damping factor, the model time delay.

20. The configuration system of claim 16 wherein the at least one mathematical model comprises a vessel system modeller.

21. The configuration system of claim 20 wherein the vessel system modeller has at least one parameter selected from a model gain, a model time constant.

22. The configuration system of claim 21 wherein the predicted thrust component and/or predicted velocity component is configured to determine a value for one or more of the model gain, the model time constant.

23. The configuration system of claim 16 wherein the predicted thrust component and/or predicted velocity component is configured to apply at least two mathematical models, the mathematical models comprising a thrust system modeller and a vessel system modeller.

24. The configuration system of any one of claims 16 to 23 wherein the at least one controller is configured to generate a plurality of thrust demands intended to cause the vessel to perform a sequence of predefined movements.

25. The configuration system of claim 24 wherein the plurality of thrust demands comprises a time varying signal that is recorded for comparison against the movement of the vessel, the time varying signal reversing direction when the vessel reaches a predefined velocity or position threshold.

26. The configuration system of claim 24 or claim 25 wherein the plurality of thrust demands comprises a step input.

27. The configuration system of claim 24 or claim 25 wherein the plurality of thrust demands comprises a sine wave.

28. The configuration system of claim 24 or claim 25 wherein the plurality of thrust demands comprises a square wave having variable amplitudes and/or periods.

29. The configuration system of any one of claims 16 to 28 further comprising a demand allocator configured to generate a thrust vector at least partly from the thrust demand, the demand allocator generating one or more of: steering demand(s) for the or at least one of the waterjets, reverse demand(s) for the or at least one of the waterjets, RPM demand(s) for the or at least one of the engines.

30. The configuration system of any one of claims 16 to 29 wherein the actual thrust determiner component is configured to determine the actual thrust generated by the manoeuvring/propulsion system by measuring one or more of: steering nozzle position for the or at least one of the waterjets, reverse duct position for the or at least one of the waterjets, RPM of the or at least one of the engines.

31. A computer readable medium on which is stored computer executable

instructions that, when executed by a processor, cause the processor to perform a method for configuring a closed loop manoeuvring and propulsion control system of a marine vessel, the manoeuvring/propulsion system comprising at least one waterjet and at least one engine, the manoeuvring/propulsion system configured to provide at least one thrust vector that acts to move the vessel along an axis, or respective axes, the method comprising :

determining the actual thrust generated by the manoeuvring/propulsion system and/or measuring an actual velocity of the vessel in response to the actual thrust vector; determining, by applying at least one mathematical model, a predicted thrust and/or predicted velocity of the vessel in response to the thrust demand and/or the actual thrust vector, the at least one mathematical model having at least one parameter;

determining an output error at least partly from at least one difference between the actual thrust and/or the actual velocity of the vessel and the predicted thrust and/or predicted velocity of the vessel;

32. The computer readable medium of claim 31 wherein the at least one

mathematical model comprises a thrust system modeller.

33. The computer readable medium of claim 32 wherein the thrust system modeller has at least one parameter selected from a model gain, a model natural frequency, a model damping factor, a model time delay.

34. The computer readable medium of claim 33, the method further comprising determining a value for one or more of the model gain, the model natural frequency, the model damping factor, the model time delay.

35. The computer readable medium of claim 31 wherein the at least one

mathematical model comprises a vessel system modeller.

36. The computer readable medium of claim 35 wherein the vessel system modeller has at least one parameter selected from a model gain, a model time constant.

37. The computer readable medium of claim 36, the method further comprising determining a value for one or more of the model gain and the model time constant.

38. The computer readable medium of claim 31, the method further comprising applying at least two mathematical models, the mathematical models comprising a thrust system modeller and a vessel system modeller.

39. The computer readable medium of any one of claims 31 to 38, the method further comprising the at least one controller generating a plurality of thrust demands intended to cause the vessel to perform a sequence of predefined movements.

40. The computer readable medium of claim 39 wherein the plurality of thrust demands comprises a time varying signal that is recorded for comparison against the movement of the vessel, the time varying signal reversing direction when the vessel reaches a predefined velocity or position threshold.

41. The computer readable medium of claim 39 or claim 40 wherein the plurality of thrust demands comprises a step input.

42. The computer readable medium of claim 39 or claim 40 wherein the plurality of thrust demands comprises a sine wave.

43. The computer readable medium of claim 39 or claim 40 wherein the plurality of thrust demands comprises a square wave having variable amplitudes and/or periods.

44. The computer readable medium of any one of claims 31 to 43, the method further comprising a demand allocator generating a thrust vector at least partly from the thrust demand, the demand allocator generating one or more of: steering demand(s) for the or at least one of the waterjets, reverse demand(s) for the or at least one of the waterjets, RPM demand(s) for the or at least one of the engines.

45. The computer readable medium of any one of claims 31 to 44 wherein determining the actual thrust generated by the manoeuvring/propulsion system comprises measuring one or more of: steering nozzle position for the or at least one of the waterjets, reverse duct position for the or at least one of the waterjets, RPM of the at least one of the engines.

46. A closed loop manoeuvring and propulsion control system of a marine vessel, the manoeuvring/propulsion system comprising at least one waterjet and at least one engine, the manoeuvring/propulsion system configured to provide at least one thrust vector that acts to move the vessel along an axis, or respective axes, the system having at least one controller configured to generate at least one thrust demand operable to cause the manoeuvring/propulsion system to generate the at least one thrust vector that causes the vessel to move along an axis, the manoeuvring/propulsion system including a configuration device, the device comprising :

a minimiser component configured to:

on detecting a minimal output error, determining the value of the at least one parameter, or at least one of the parameters; and a controller gain determiner configured to determine at least one controller gain associated to the at least one controller based at least partly on the at least one determined parameter value, or at least one of the determined parameter values.

47. The system of claim 46 wherein the at least one mathematical model comprises a thrust system modeller.

48. The system of claim 47 wherein the thrust system modeller has at least one parameter selected from a model gain, a model natural frequency, a model damping factor, a model time delay.

49. The system of claim 48 wherein the predicted thrust component and/or predicted velocity component is configured to determine a value for one or more of the model gain, the model natural frequency, the model damping factor, the model time delay.

50. The system of claim 46 wherein the at least one mathematical model comprises a vessel system modeller.

51. The system of claim 50 wherein the vessel system modeller has at least one parameter selected from a model gain, a model time constant.

52. The system of claim 51 wherein the predicted thrust component and/or predicted velocity component is configured to determine a value for one or more of the model gain, the model time constant.

53. The system of claim 46 wherein the predicted thrust component and/or predicted velocity component is configured to apply at least two mathematical models, the mathematical models comprising a thrust system modeller and a vessel system modeller.

54. The system of any one of claims 46 to 53 wherein the at least one controller is configured to generate a plurality of thrust demands intended to cause the vessel to perform a sequence of predefined movements.

55. The system of claim 55 wherein the plurality of thrust demands comprises a time varying signal that is recorded for comparison against the movement of the vessel, the time varying signal reversing direction when the vessel reaches a predefined velocity or position threshold.

56. The system of claim 54 or claim 55 wherein the plurality of thrust demands comprises a step input.

57. The system of claim 54 or claim 55 wherein the plurality of thrust demands comprises a sine wave.

58. The system of claim 54 or claim 55 wherein the plurality of thrust demands comprises a square wave having variable amplitudes and/or periods.

59. The system of any one of claims 46 to 58 further comprising a demand allocator configured to generate a thrust vector at least partly from the thrust demand, the demand allocator generating one or more of: steering demand(s) for the or at least one of the waterjets, reverse demand(s) for the or at least one of the waterjets, RPM demand(s) for the or at least one of the engines.

60. The system of any one of claims 46 to 59 wherein the actual thrust determiner component is configured to determine the actual thrust generated by the

manoeuvring/propulsion system by measuring one or more of: steering nozzle position for the or at least one of the waterjets, reverse duct position for the or at least one of the waterjets, RPM of the or at least one of the engines.

61. A configuration device adapted to configure a closed loop manoeuvring and propulsion control system of a marine vessel, the manoeuvring/propulsion system comprising at least one waterjet and at least one engine, the manoeuvring/propulsion system configured to provide at least one thrust vector that acts to move the vessel along an axis, or respective axes, the system having at least one controller configured to generate at least one thrust demand operable to cause the manoeuvring/propulsion system to generate the at least one thrust vector that causes the vessel to move along an axis, the configuration device comprising :

a minimiser component configured to: determine an output error at least partly from at least one difference between the actual thrust and/or the actual velocity of the vessel and the predicted thrust and/or predicted velocity of the vessel,

62. The configuration device of claim 61 wherein the at least one mathematical model comprises a thrust system modeller.

63. The configuration device of claim 62 wherein the thrust system modeller has at least one parameter selected from a model gain, a model natural frequency, a model damping factor, a model time delay.

64. The configuration device of claim 63 wherein the predicted thrust component and/or the predicted velocity component is configured to determine a value for one or more of the model gain, the model natural frequency, the model damping factor, the model time delay.

65. The configuration device of claim 61 wherein the at least one mathematical model comprises a vessel system modeller.

66. The configuration device of claim 65 wherein the vessel system modeller has at least one parameter selected from a model gain, a model time constant.

67. The configuration device of claim 66 wherein the predicted thrust component and/or predicted velocity component is configured to determine a value for one or more of the model gain, the model time constant.

68. The configuration device of claim 61 wherein the predicted thrust component and/or predicted velocity component is configured to apply at least two mathematical models, the mathematical models comprising a thrust system modeller and a vessel system modeller.

69. The configuration device of any one of claims 61 to 68 wherein the at least one controller is configured to generate a plurality of thrust demands intended to cause the vessel to perform a sequence of predefined movements.

70. The configuration device of claim 69 wherein the plurality of thrust demands comprises a time varying signal that is recorded for comparison against the movement of the vessel, the time varying signal reversing direction when the vessel reaches a predefined velocity or position threshold.

71. The configuration device of claim 69 or claim 70 wherein the plurality of thrust demands comprises a step input.

72. The configuration device of claim 69 or claim 70 wherein the plurality of thrust demands comprises a sine wave.

73. The configuration device of claim 69 or claim 70 wherein the plurality of thrust demands comprises a square wave having variable amplitudes and/or periods.

74. The configuration device of any one of claims 61 to 73 further comprising a demand allocator configured to generate a thrust vector at least partly from the thrust demand, the demand allocator generating one or more of: steering demand(s) for the or at least one of the waterjets, reverse demand(s) for the or at least one of the waterjets, RPM demand(s) for the or at least one of the engines.

75. The configuration device of any one of claims 61 to 74 wherein the actual thrust determiner component is configured to determine the actual thrust generated by the manoeuvring/propulsion system by measuring one or more of: steering nozzle position for the or at least one of the waterjets, reverse duct position for the or at least one of the waterjets, RPM of the or at least one of the engines.