Hybrid control unit for a watercraft

Abstract

A control unit for a watercraft propulsion system, the watercraft propulsion system comprising an internal combustion engine and an electric drive, wherein the control unit comprises a processing device configured to: receive data indicating a condition of the watercraft or its environment; input the received data to a model; and in dependence on the received data, control the propulsion system so as to adapt a proportion of the total drive provided by the propulsion system supplied by the electric drive, wherein the proportion of the total drive to be provided by the electric drive is determined in dependence on the output of the model.

Description

[0001] HYBRID CONTROL UNIT FOR A WATERCRAFT

[0002] FIELD OF THE INVENTION

[0003] This invention relates to a control unit for a watercraft, in particular to a control unit for a hybrid-powered watercraft.

[0004] BACKGROUND

[0005] Following the growing success of electric-powered vehicles and hybrids in the automotive market, similar trends have recently been seen in the watercraft market.

[0006] For example, hybrid-powered boats may improve fuel economy by using batteries to assist petrol or diesel-powered engines, whilst also having the option to operate using solely electric power. Electric motors driven by electrical batteries are more efficient than internal combustion engines, with high power-to-weight ratios providing torque over a wide speed range. The electric motor may also react more quickly to control signals than the engine. Such watercraft may produce less noise and have less environment impact than traditional engine-powered watercraft.

[0007] There may be certain environmental or conditional circumstances of the watercraft in which it is desirable to supply a greater proportion of drive from the electric drive.

[0008] SUMMARY OF THE INVENTION

[0009] According to one aspect of the present invention there is provided a control unit for a watercraft propulsion system, the watercraft propulsion system comprising an internal combustion engine and an electric drive, wherein the control unit comprises a processing device configured to: receive data indicating a condition of the watercraft or its environment; and in dependence on the received data, control the propulsion system so as to adapt a proportion of the total drive provided by the propulsion system supplied by the electric drive. According to another aspect of the present invention there is provided a control unit for a watercraft propulsion system, the watercraft propulsion system comprising an internal combustion engine and an electric drive, wherein the control unit comprises a processing device configured to: receive data indicating a condition of the watercraft or its environment; input the received data to a model; and in dependence on the received data, control the propulsion system so as to adapt a proportion of the total drive provided by the propulsion system supplied by the electric drive, wherein the proportion of the total drive to be provided by the electric drive is determined in dependence on the output of the model.

[0010] In dependence on the received data, the control unit may be configured to adapt a proportion of the total drive provided by the propulsion system supplied by the internal combustion engine.

[0011] In dependence on the received data, the control unit may be configured to control the propulsion system such that no drive is supplied by the internal combustion engine.

[0012] The watercraft may be a hybrid watercraft. The propulsion system may comprise a hybrid drive assembly. The control unit may be configured to send a signal to the hybrid drive assembly to cause a determined proportion of the total drive to be supplied by the electric drive.

[0013] The hybrid drive assembly may comprise an electric motor, the electric motor configured to be driven to provide a motor output torque by one or more of the electric drive and an engine output torque of the internal combustion engine.

[0014] The electric drive may comprise a battery.

[0015] The battery may be configured to provide the respective proportion of the total drive provided by the propulsion system supplied by the electric drive.

[0016] The processing device may be configured to receive data indicating a condition of the watercraft or its environment from one or more sensing devices. The one or more sensing devices may be sensing devices of the watercraft or may be communicatively coupled to the watercraft and optionally remote from the watercraft.

[0017] The processing device may be configured for wireless or wired communication with the one or more sensing devices.

[0018] The one or more sensing devices may comprise one or more of an image sensor, an accelerometer, a gyroscope, a location sensor, a moisture sensor, a freeboard sensor, a fuel level sensor, a proximity sensor, a motion sensor, a pressure sensor, a flow rate sensor, a temperature sensor, a strain gauge, a linear potentiometer and a rotary potentiometer.

[0019] The control unit may be configured to determine from the received data that the watercraft or a part thereof is in a geographical location. The control unit may be configured to adapt the proportion of the total drive provided by the propulsion system supplied by the electric drive in dependence on the determined geographical location.

[0020] The received data may provide an indication of a parameter associated with the condition of the watercraft or its environment (such as the performance of the watercraft, or the efficiency of the watercraft).

[0021] The control unit may be configured to: receive the data associated with a condition of the watercraft or its environment; determine from the received data a value of the parameter associated with the condition of the watercraft or its environment; and adjust the proportion of the total drive supplied by the electric drive in dependence on the value of the parameter.

[0022] The control unit may be further configured to: categorize the value of the parameter into one of a plurality of ranges of the parameter; and adjust the proportion of the total drive supplied by the electric drive in dependence on the one of the plurality of ranges of the parameter.

[0023] Each value or range of values of the parameter may correspond to a respective proportion of total drive to be supplied by the electric drive. The processing device may be configured to adapt the proportion of the total drive provided by the propulsion system to be supplied by the electric drive if the value of the parameter exceeds a predetermined threshold or is below a predetermined threshold.

[0024] The control unit may be configured to cause the electric drive to adjust the proportion of the total drive proportionally or inversely proportionally to the value of the parameter determined from the received data.

[0025] The control unit may comprise a memory for storing data previously received by the processing device and / or values of parameters determined from the received data.

[0026] The received data may indicate one or more of: a bank angle of the watercraft, a pitch value of the watercraft, a roll value of the watercraft, a trim of the watercraft, an attitude of the watercraft, the speed of the watercraft, the efficiency of the watercraft, pilot comfort, an indication of a weather condition, an indication of water conditions, an indication of fuel level and a geographical location of the watercraft or a part thereof.

[0027] The processing device may be configured to input the received data to a model, wherein the proportion of the total drive to be provided by the electric drive is determined in dependence on the output of the model.

[0028] The model may be a trained artificial intelligence model. The model may be a trained machine learning model.

[0029] The control unit may be communicatively connectable to one or more user control interfaces. The control unit may be further configured to control the propulsion system so as to adapt a proportion of the total drive provided by the propulsion system supplied by the electric drive in response to one or more user inputs to the user control interface(s). The processing device may be configured to: input at least part of the received data to a drag model for the watercraft; and determine the proportion of the total drive to be provided by the electric drive in dependence on the output of the drag model.

[0030] The output of the drag model may be used as a feedforward control to determine the proportion of the total drive to be provided by the electric drive.

[0031] The input to the drag model may comprise the static attitude of the watercraft. The output of the drag model may be an estimated mass and / or centre of gravity of the watercraft. The processing device may be configured to determine the proportion of the total drive to be provided by the electric drive in dependence on the estimated mass and / or centre of gravity of the watercraft.

[0032] The model may comprise respective efficiency models of the internal combustion engine and the electric drive. The processing device may be configured to input at least part of the received data to each of the efficiency models. The respective efficiency models may output respective efficiency values for the internal combustion engine and the electric drive. The proportion of the total drive to be provided by the electric drive may be determined in dependence on the outputs of the respective efficiency models for the internal combustion engine and the electric drive.

[0033] According to another aspect, there is provided a watercraft comprising: a propulsion system comprising an internal combustion engine and an electric drive; and a control unit having any of the features described herein.

[0034] According to another aspect there is provided a method of controlling a propulsion system for a watercraft, the method comprising: receiving data indicating a condition of the watercraft or its environment; and in dependence on the received data, controlling the propulsion system so as to adapt a proportion of the total drive provided by the propulsion system supplied by the electric drive.

[0035] According to another aspect, there is provided a computer-readable storage medium have stored thereon computer readable instructions that when executed at a computer system comprising one or more processors cause the one or more processors to perform the method above. The computer-readable storage medium may be a non- transitory computer-readable storage medium.

[0036] DESCRIPTION OF THE DRAWINGS

[0037] The present invention will now be described by way of example with reference to the accompanying drawings. In the drawings:

[0038] Figure 1 schematically illustrates a boat with a propulsion system for powering movement of the boat.

[0039] Figure 2 schematically illustrates components of an exemplary propulsion system for a watercraft having a parallel hybrid layout.

[0040] Figure 3 schematically illustrates some components of a hybrid drive assembly.

[0041] Figure 4 schematically illustrates a control unit for a hybrid-powered watercraft.

[0042] Figure 5 shows an example of a control unit for the propulsion system of a watercraft.

[0043] Figure 6 schematically illustrates a watercraft in a harbour.

[0044] Figure 7 shows an example of a method for controlling a propulsion system of a watercraft.

[0045] DETAILED DESCRIPTION

[0046] The following description is presented to enable any person skilled in the art to make and use the invention and is provided in the context of a particular application. Various modifications to the disclosed embodiments will be readily apparent to those skilled in the art.

[0047] The general principles defined herein may be applied to other embodiments and applications without departing from the present invention. Thus, the present invention is not intended to be limited to the embodiments shown, but is to be accorded the widest scope consistent with the principles and features disclosed herein.

[0048] In the present specification the term “engine” is used to mean an internal combustion engine, which burns fuel, such as petrol or diesel, to generate power. The term “motor” is used to mean a device that can use electrical energy to generate power. A watercraft such as a boat or ship may be propelled by an engine and / or a motor. The watercraft may be a marine or freshwater vessel. The watercraft may be, for example but not limited to, a boat, ship, hovercraft, jetski or submarine. The term “drive mechanism” is used to mean any form of drive for a watercraft powertrain. A drive mechanism may comprise one or more engines and / or motors. A "powertrain” or “propulsion system” may comprise one or more of an engine, a motor and a gearbox.

[0049] The word hybrid, in the context of a powertrain, is used to mean of mixed electric and non-electric character. Therefore, a hybrid watercraft is a watercraft having more than one mechanism via which drive can be provided. In the examples described herein, the watercraft has a propulsion system comprising an internal combustion engine and an electric drive.

[0050] Figure 1 shows one example of a boat 100 having a hull 101 comprising a stem 102. A powertrain container 103 is provided. The powertrain container houses a propulsion system 104 for driving the boat. The powertrain container may be sealable to exclude water from entering. The powertrain container is located at the stem 102 of the boat. The powertrain container is mounted relative to the hull so as to increase the buoyancy of the boat. The sealable container 103 has an opening for permitting access to its interior. The opening can be closed and sealed by a lid 105.

[0051] In this example, the propulsion system 104 is connected to a driveshaft 106 that is coupled to and transmits drive to a propellor 107. However, the propulsion system may alternatively comprise an impellor or ajet drive. In this example, the propellor is located outside the container. Moulded protrusions in the container 103 may serve as securing means 108 that support the drive mechanism 104 in the container and hold it securely. The drive mechanism 104 may be removable from the container 103. The two securing means 108 shown on either side of a drive mechanism are illustrative, but the number, configuration and position of securing means varies with the particular drive mechanism and additional components in the container. An attachment for the drive mechanism 109 is shown extending from an internal surface of the container to the drive mechanism 104. The attachment for the drive mechanism 109 may penetrate the transom of the boat and be cantilevered from inside the hull.

[0052] The propellor may be mounted so that it is located below the base of the container. The propellor may be located under the container or rearward of and lower than the container.

[0053] In this example, the propulsion system is contained within a sealable powertrain container 103. However, the propulsion system may also be located on the exterior of the boat. An underside 110 of the sealable powertrain container is shown stepped relative to an underside of the boat. The forward edge of the underside of the powertrain container abuts the transom. The base of the powertrain container is offset from and above the underside of the hull where the underside of the hull meets the transom. There is a portion of the transom exposed to the exterior of the boat and located vertically between the underside of the hull and the base of the powertrain container. That portion of the transom extends in a generally upright direction when the boat is in its static floating attitude. When the boat is in its static floating attitude the underside 110 of the powertrain container is shallower in the water than the deepest part of the underside of the hull where it meets the transom. When the boat is in motion, the stepped transition from the underside of the hull to the base of the container can result in laminar flow of water from the base of the hull to the region under the container and rearward thereof. The propellor can be located in that region. This can result in improved efficiency of the propellor. The propeller may alternatively be located in other regions.

[0054] The boat may also comprise one or more sensors 406 for measuring parameters relating to conditions of the boat and its environment, as will be described in more detail below. In the specific example illustrated in Figure 1 , the sensors 406 are freeboard sensors. These sensors are configured to detect the distance between the respective sensor 406 and the waterline 407 in a perpendicular direction, as indicated at 408. Such sensors can be used to measure the height of the deck or the hull above the waterline at different points along the length of the watercraft. Measurements from the freeboard sensors can be used to determine parameters such as the attitude or trim of the boat, wave height and sea state.

[0055] Components of the propulsion system 104 are schematically illustrated in more detail in Figure 2. The components of the propulsion system can be located inboard of the hull, outboard of the hull, or a combination of inboard and outboard.

[0056] In this example, the propulsion system has a parallel layout. However, any other layout may alternatively be used. The propulsion system comprises an internal combustion engine 201 and a hybrid drive assembly (HDA) 202. The HDA is connectable to an electric power source, such as a battery 203. Typically, a battery used in such applications produces a voltage which can range from the order of 250V to what could be considered a high voltage of around 400V or 800V. A voltage of this magnitude is beneficial for producing a suitably high power for driving the motor. The battery 203 is connected to the HDA 202 via connections 209, 210 which are each connected to a terminal of the battery 203.

[0057] The battery may be a DC traction battery. For example, such a battery may be used as the traction source to drive the electric motors to propel an electric or hybrid watercraft such as a boat. However, it is common for the energy from such a battery to be additionally used to drive other components of the watercraft, such as lights, air conditioning units etc. These other components might need to operate at a lower voltage. One or more converters may be used in the system to convert the voltage from the battery to a voltage suitable for use in the one or more other components.

[0058] The engine 201 may comprise a low voltage alternator, as is conventional for an engine.

[0059] Shafts 205 and 206 transmit torque between the engine 201 and the HDA 202 and provide the output torque from the HDA 202 to the drive system 204 respectively. The drive system 204 may comprise a final gearbox and a waterproof coupling through the transom. A shaft 207 provides drive from the drive system 204 to the propellor 208. One or more of the shafts 205, 206 and 207 may each comprise one or more torque sensors which can measure torque and / or provide feedback to the controller, as described below.

[0060] The HDA is shown in more detail in Figure 3. The HDA comprises one or more electric motors 301 . The HDA may also comprise a transmission 302. Transmission 302 may be a gear box. However, in other implementations there may be no gears. The HDA may comprise further components, such as a cooling pack, power electronics, interface boards and a mounting system.

[0061] The motor 301 may comprise multiple windings which are supplied with current from the battery. The current supplied to the electric motor by the battery can be supplied via an inverter circuit, which supplies current to windings of the motor. In one example, the motor may be a three-phase induction motor having three windings. The windings are each wound around a core. When electrical power is supplied to the windings, each respective core is magnetised and drives rotors of the motor. The current in each winding is 120 degrees out of phase with the current in the other windings.

[0062] A DC voltage is supplied to the HDA 202 by the battery 203. The DC voltage may be converted to AC by an inverter circuit and the supplied to the electric motor 301 .

[0063] The electric motor 301 may be entirely driven by electricity from the battery 203 or by torque from the engine 201 , or by a combination of both. In one simple arrangement, the shaft 206 of the motor 301 can be caused to rotate by either of (i) electricity from the battery 203 and (ii) torque from the engine 201 .

[0064] If the motor 301 of the HDA 202 is back-driven, for example by the engine 201 or by the propeller 208 if a current is flowing past the vessel when it is stationary, the HDA may also be able to charge the battery. This may be advantageous if it is desirable to use the motor to brake the propeller by providing reverse drive from the motor or if the battery is flat and it is desired to use the electric drive in a particular situation.

[0065] There may be a mechanical one-way mechanism between the engine and the motor. This may be used to prevent the engine back-driving the motor. For example, there may be a first drive shaft between the engine and the propellor, and a second shaft coupled to the first shaft with the electric motor connected to that second shaft by a sprag clutch. The sprag clutch may have cam-shaped steel wedges (or sprags) that are placed at an angle and control one-way direction of movement. When the movement tries to go in the opposite direction an instant driving disengagement or locking occurs. Alternatively, the second shaft may be coupled to the first shaft by another type of mechanical diode, such as an axial finger arrangement.

[0066] The control architecture for the propulsion system, which will now be referred to as a powertrain, is schematically illustrated in Figure 4.

[0067] A powertrain control unit (PCU) 401 is a central control unit for controlling the components of the powertrain. The PCU 401 comprises a processor and a memory. The memory stores in a non-transient way software that is executable by the processor. The memory may also store data previously received by the PCU. The PCU may also comprise one or more transceivers for receiving or transmitting data. The PCU may be connected to other components wirelessly or via a wired connection. In this example, the components of the control architecture are connected via a communication bus to the PCU 401 .

[0068] In this example, the control architecture also comprises a Human Machine Interface (HMI) 402, a battery management system (BMS) 403 and an engine controller 404. The HMI 401 may, for example, comprise a display panel displaying parameters relating to the powertrain. The BMS may perform functions such as protecting the battery from operating outside of its safe operating area and monitoring its state. The BMS may provide signals to the PCU 401. The engine controller 404 may be a conventional controller for an internal combustion engine and may control for example, the amount of fuel to inject to the engine based on readings from sensors in the engine. The engine controller 404 receives signals from the PCU.

[0069] The PCU 401 is also connected to user controls 405. User controls 405 allow the user to control, for example, the total drive and / or direction of motion of the watercraft and may allow the user to select between an entirely electric mode and a hybrid mode of operation when operating in a manual mode. The user controls may comprise a throttle. The PCU may also provide signals to the user controls 405. Figure 5 schematically illustrates further details of the control unit 401 for a watercraft that can perform the functions described herein. Figure 5 shows some of the components of the control unit. The control unit 401 may comprise at least one processor, such as processor 501 and at least one memory, such as memory 502. The memory stores in a non-transient way code that is executable by the processor(s) to implement the device in the manner described herein. The control unit may also comprise a transceiver 503 for receiving data indicating a condition of the watercraft or its environment. The connection of various sensors of the watercraft to the transceiver may be wireless or wired.

[0070] From data received from the sensor(s), the control unit may determine one or more parameters relating to a condition of the watercraft or its environment. The sensors can provide their sensed data to the control unit. In dependence on the data received from the sensor(s) and / or one or more parameters determined from the data, the powertrain control unit may be configured to preferentially adjust the output drive of the electric drive. Therefore, in dependence on the data received from the sensors, the PCU 401 can control the propulsion system so as to adapt the proportion of the total drive supplied by the electric drive. In dependence on the data received from the sensors, the PCU 401 may also adjust parameters such as propeller pitch, propeller angle incident vertically to the water (trim), propeller depth in the water, propeller angle incident to the water (steering), or the position of objects or loads.

[0071] The sensor may be any suitable sensing device. In some non-limiting examples, the sensor may be an image sensor, an accelerometer, a gyroscope, a location sensor, a moisture sensor, a freeboard sensor, a fuel level sensor, a proximity sensor, a motion sensor, a position sensor (for sensing linear or rotational position) or a radar. The PCU may receive data from multiple sensors and adapt the proportion of the total drive supplied by the electric drive in dependence on the data received from the multiple sensors.

[0072] In some cases, the output from the engine may remain constant and the amount of drive provided by the electric drive may be increased accordingly, such that the proportion of the total drive supplied by the electric drive is increased. In some cases, the output from the engine may remain constant and the amount of drive provided by the electric drive may be decreased, for example so that a proportion of the output of the engine is harvested to the battery, or for some other reason. However, in other embodiments, the output of the engine may also be adjusted in dependence on the received data. Therefore, the control unit may be configured to, in dependence on the received data, determine a first proportion of the total drive to be provided by the electric drive and a second proportion of the total drive to be provided by the engine (where the sum of the first and second proportions is equal to the total drive provided by the propulsion system). For example, the control unit may cause a decrease in the output of the engine so that the proportion of the total drive supplied by the engine is reduced and the proportion of the total drive supplied by the electric drive is increased.

[0073] In one example, the control unit may receive an input from one or more sensors, such as freeboard sensors 406 in Figure 1 . In dependence on the data from these sensors, which may provide an indication of parameters such as the trim of the boat, wave height and sea state, the control unit may be configured to adjust the drive provided by the electric drive.

[0074] In another example, a banking angle of the watercraft while turning may be determined from sensor data and compared to accelerometer data to determine the maximum power possible to be safely applied in turns. The sensor data may also indicate loading characteristics of the watercraft, for example if the watercraft has a very light weight, or very heavy weight, and / or where the weight is positioned. This could influence the amount of power required and the handling of the watercraft in heavy seas, which may further influence the level of interference by the PCU. In dependence on the sensor data, the control unit may move propulsion trim up or down, for example for increased efficiency, or to increase wave 'cutting' abilities. In dependence on the sensor data, the control unit may increase the proportion of electric drive, or increase the proportion of harvesting, to instantaneously add or remove some of the total drive.

[0075] In another example, in dependence on the sensor data, the propulsion system may be controlled to reduce the proportion of total drive provided by the electric drive so that there is more electrical power in reserve to aid climbing large waves. In another example, the propulsion system may be controlled to increase the proportion of the total drive provided by the electric drive for lighter vessels (as determined in dependence on one or more weight sensors) to decrease emissions without affecting range as much. Additionally, the proportion of electric drive may be controlled in dependence on measured aerodynamic forces causing more or less of the hull to be in contact with the water at higher speeds.

[0076] In another example, the control unit may receive an input from one or more accelerometers or gyroscopes of the watercraft. Multiple accelerometers may measure acceleration in three perpendicular directions, for example along x, y and z directions relative to a reference orientation, such as the centre of the Earth. Gyroscopes can be used to measured angular velocity. These sensors can be used to determine the orientation of the watercraft relative to a common reference, or to detect vibrations and / or motion of the watercraft, such as lateral acceleration from increasing or decreasing speed, or cornering. If the data from these sensors indicates that the watercraft is, for example moving up and down due to choppy waters, the control unit can take a greater proportion of drive from the electric drive. Using a greater proportion of electric drive may provide greater potential to influence the drive quickly, utilising the reaction speed of the electric drive. Data from the sensors can also be used by the processor to determine parameters such as watercraft attitude, directional shock and bank angle and the control unit may adapt the proportion of drive provided by the electric drive in dependence on the received data.

[0077] In the case of sensor data indicating that power to the water is being lost (i.e. leaving the water from the crest of a wave), for example from a torque sensor on a shaft, it may be advantageous to brake the propeller or impeller of the watercraft with the electric drive, and then bring the speed back up upon re-entry with the electric drive. In these circumstances it could be advantageous to increase the proportion of the total drive provided by the electric drive to have greater speed of control over the total power put to the water. Using a greater proportion of the total drive from the electric drive may also be desirable to increase power in turns to avoid speed reduction. Similarly, harvesting power during turns that are too fast would have the effect of increased slowing in the turn to bring the watercraft within safe cornering parameters. The proportion of the total drive supplied by the electric drive may also be determined in dependence on the speed of the watercraft, as determined from data from one or more sensors. For example, below a certain speed, such as 10 knots, it may be advantageous to switch to as high a proportion of electric drive as possible to have increased control. This condition could also change the throttle mapping to have more controllability. At high speeds, it may be desirable to reduce the proportion of the total drive provided by the electric drive to minimal levels to allow the required speed to be kept stable when, for example, climbing waves. An additional amount of electric drive can be used to avoid speed loss, which could be specified by the user (as, for example, some users may desire maximum dual deployment for maximum possible speed).

[0078] In another example, the control unit may receive an input from one or more location sensors on the watercraft. A location sensor may provide an indication that the watercraft or a part thereof is in a particular geographical location. For example, the control unit may receive data from a Global Positioning System (GPS) of the watercraft. In dependence on the data received from the location sensor(s), the control unit may adjust the proportion of the total drive that is provided by the electric motor. For example, if the GPS system detects that the watercraft is in a geographical location corresponding to a harbour or other speed- or noise-controlled geographical area, such as a marine protected area, the control unit may be configured to use a greater proportion of drive from the electric drive rather than the engine. This may allow for quieter propulsion of the watercraft and / or allow greater control of speed when manoeuvring the watercraft around objects in the area.

[0079] In one particular implementation, the user may be able to select one or more areas on a map where it is desirable to use a greater proportion of electric drive, for example for noise or speed control purposes. The user may be able to select these geographical areas via the HMI and the resulting geographical areas may be stored in the memory of the control unit. In dependence on the data received from a location sensor, the control unit may determine from the stored map that the watercraft or a part thereof is located within a geographical area selected by the user and adjust the proportion of the total drive to be provided by the electric drive accordingly.

[0080] In another example, as schematically illustrated in Figure 6, the control unit 401 of a watercraft 601 may detect that the watercraft is in a geographical area 602 having a relatively high density of other watercraft 603. It may do this by receiving signals emitted by other watercraft 603 in the area, such as Automatic Identification System (AIS), or by analysis of radar signals. This may allow the watercraft to detect that it is in an environment where there is a relatively high density of watercraft, such as a harbour. For example, it may detect that there are more than 10 watercraft in an area of 200m2. In response to detecting that it is in a geographical area having a relatively high density of watercraft, the control unit 401 of the watercraft 601 may adjust the proportion of drive to be provided by the electric drive accordingly. For example, the control unit may control the propulsion system to be driven using only the electric drive. This may allow the watercraft to move through the harbour area with greater control using the electric drive and reduced noise and emissions.

[0081] The sensor data could also be used to adjust the throttle map, such that more change in throttle input is required to effect the same power to the water. For example, 10 degrees of throttle movement could initially equal 50% power. This could be changed to be only 10% vessel power.

[0082] In another example, by combining current location and heading, and a navigation route plan, the proportion of electric drive could be adjusted to provide more harvesting if necessary to ensure sufficient battery reserves for harbour manoeuvring.

[0083] The control unit may also detect that the watercraft is in proximity to other objects in the water and, in response, the control unit of the watercraft may adjust the proportion of drive to be provided by the electric drive accordingly. As mentioned previously, the control unit may also adjust how electric drive is applied in response to given throttle movements. For example, the control unit may control the propulsion system to be driven using only the electric drive. The control unit may be able to detect that the watercraft is in proximity to one or more objects by receiving signals from proximity or motion sensors on the watercraft. Proximity sensors may be, for example, capacitive, inductive, magnetic optical or ultrasonic or use radar or microwaves to detect the proximity of objects. Thus, when the control unit detects that the watercraft or a part thereof is within a predetermined distance of one or more objects, such as other watercraft, non-self-propelled vessels, wrecks, rocks, icebergs, marine mammals, seaweed, buoys or structures such as harbour walls or rigs, the control unit may, for example, control the propulsion system such that a greater proportion (or all) of the drive is supplied by the electric drive. This may allow the watercraft to respond more quickly to user input to the user controls and / or HMI to allow the watercraft to be manoeuvred around objects in the water.

[0084] In one implementation, the PCU may receive the data from one or more of the sensors, which can provide an indication of a parameter associated with the condition of the watercraft or its environment. For example, data received from the freeboard sensors may provide an indication of the trim of the watercraft. The PCU may implement an algorithm or model to determine the parameter from the received data or the sensors may record the value of the parameter directly.

[0085] The PCU may control the propulsion system so as to adapt the proportion of the total drive supplied by the electric drive if the value of the parameter exceeds a predetermined threshold. Alternatively, it may adapt the proportion of the total drive supplied by the electric drive if the value of the parameter is less than a predetermined threshold.

[0086] In another implementation, the control unit may be configured to store data indicating multiple values ranges of parameters that can be derived from received data (received from the sensors of the watercraft or otherwise) and a corresponding drive setting for each of the multiple values or ranges. Each drive setting may indicate a proportion of the total drive to be provided by the electric drive and / or the engine. When the control unit receives the data, it can, for example, determine which range of the multiple ranges the received data belongs to and output a signal to the HDA to adjust the proportion of drive provided by the engine and / or the electric drive in accordance with the drive setting for that range.

[0087] For example, from received data providing an indication of the pitch of the watercraft, the value of the pitch of the watercraft may be categorized into one of multiple pitch ranges. For example, the multiple ranges may be 0-5, 5.1-10, 10.1-15 degrees and so on. The memory of the PCU may store values of the proportion of the total drive to be supplied by the electric drive for particular values or ranges of values of parameters. This may for example be stored in a lookup table, with a value or range of values for a parameter in the cells of a first column and a corresponding drive setting (i.e. the proportion of drive to be provided by the electric drive) in the cells of a second column. Upon receiving the data and determining the indication of the parameter, the PCU can categorize the received data into one of the multiple ranges and then control the propulsion system such that a proportion of the total drive provided by the electric drive is as given in the lookup table for that range of the parameter.

[0088] The control unit may be configured to receive data from one or more sensors located at a fuel tank of the watercraft for supplying the internal combustion engine of the propulsion system. The data from the sensor(s) may indicate a level of fuel in the tank. In dependence on the data indicating the level of fuel, the control unit may control the proportion of drive to be provided by the electric drive. The control unit may be configured to automatically increase the proportion of total drive provided by the electric drive when, for example, the data from a fuel tank sensor indicates that the fuel level is below a predetermined threshold.

[0089] The indicated fuel level could also be used, for example with a suitable pumping device and a plurality of tanks, to transfer fuel between tanks in different areas of the vessel, to change the trim of the vessel for increased efficiency or better seakeeping without the use of inefficient devices such as trim tabs, or use of the propeller / impeller trim device. This approach can also be used for seawater ballast tanks, filling / emptying and / or redistributing weight for efficiency or seakeeping.

[0090] Similarly, the control unit may be configured to receive data from one or more sensors indicating the battery charge level of the battery for powering the electric drive. In dependence on the data indicating the battery level, the control unit may control the proportion of drive to be provided by the electric drive. For example, the control unit may be configured to automatically decrease the proportion of total drive provided by the electric drive when, for example, the data from the battery sensor indicates that the battery charge level is below a predetermined threshold.

[0091] Additionally, with data received from position sensors (for example affixed to the position of the traction battery), and / or load sensors (for example a strain gauge on seating supports) and with a load moving device (such as a linear ballscrew), high density loads such as the traction battery could be moved in their relative positions to adjust vessel trim. This may improve vessel efficiency and seakeeping. This approach could also be applied to the positions of, for example, ballast tanks, pilot control console and seating, passenger seating and transported loads.

[0092] The control unit may be configured to receive data from an image sensor, such as a camera. The camera may be configured to capture images, including video comprising multiple images frames, and determine a condition of the watercraft or its environment from the image(s). For example, data from the image sensor may be input to an image processing algorithm or model to determine one or more characteristics of a scene captured by the image. For example, processing of the image may result in output data indicative of poor visibility due to the presence of fog or rain. The control unit may alternatively or additionally receive data from a weather system of the watercraft. For example, if a fog or severe weather warning is issued, this may be indicated to the control unit. In response, the control unit may increase the proportion of drive provided by the electric drive to allow more rapid response of the propulsion system to inputs to the user controls to allow obstacles that may be encountered at short range due to poor visibility to be avoided.

[0093] The PCU may input the received data to an algorithm or model to determine the optimal drive parameters (including the proportion of the total drive provided by the propulsion system supplied by the electric drive) for the conditions of the watercraft or its environment that are indicated by the received data. The model may give an output that indicates the proportion of the total drive to be provided by the electric drive. The PCU may then control the propulsion system accordingly in dependence on the output of the model. For example, the processor may be configured to implement a trained artificial intelligence model or machine learning model that outputs control parameters to control the HDA accordingly in dependence on the data input to the model. The model may have been trained to output a suitable proportion of drive to be provided by the electric drive based on previously collected data or sets of training data.

[0094] The model may determine the proportion of drive to be supplied by the electric drive to result in the maximum efficiency and / or minimum energy consumption of the propulsion system for a given condition of the watercraft or its environment, as indicated by the received data. The model may be trained to minimise a loss function with maximum efficiency and / or minimum energy consumption of the propulsion system as an objective of the loss function.

[0095] Where the propulsion system comprises an electric drive and an internal combustion engine, the model may optimise the torque demand split between the internal combustion engine and the electric drive. The control unit may control the propulsion system so as to adapt a proportion of the total drive provided by the propulsion system supplied by the electric drive to optimise the torque demand split between the internal combustion engine and the electric drive. The optimal torque demand split may be determined in dependence on the output of the model.

[0096] In some implementations, the control unit for the propulsion system may have an operating mode in which the propulsion system is controlled to minimise energy consumption and / or maximise efficiency given a maximum desired speed for the watercraft. The operator of the watercraft may input a maximum desired speed for the watercraft. The control unit may receive a signal in response to the operator setting a maximum desired speed of the watercraft. The signal may indicate the maximum desired speed. The control unit may control the propulsion system to maintain the speed of the watercraft at or below the maximum desired speed. In this case, the model may optimise the speed of the watercraft and / or minimise the energy consumption of the propulsion system in dependence on the received data indicating a condition of the watercraft or its environment, which is input to the model along with the maximum desired speed. The propulsion system may be controlled to operate at a lower speed than the desired maximum speed input by the operator if the model determines that the lower speed is more efficient.

[0097] The model may comprise a drag model for the watercraft. The drag model may be used as a feedforward controller. The received condition of the watercraft and / or its environment may be input to the drag model. The control unit may control the propulsion system so as to adapt a proportion of the total drive provided by the propulsion system supplied by the electric drive in dependence on the output of the drag model. The drag model may use the static attitude of the watercraft to estimate the mass or centre of gravity of the watercraft based on uncertain numbers of passengers. The drag model may forecast future drag on the watercraft based on the received condition of the watercraft or its environment (for example, in dependence on sea state). The drag model may be updated based on real-time data.

[0098] The model implemented by the control unit of the watercraft may comprise respective efficiency models for the internal combustion engine and the electric drive. The control unit may control the propulsion system so as to adapt a proportion of the total drive provided by the propulsion system supplied by the electric drive in dependence on the respective outputs of the efficiency models for the internal combustion engine and the electric drive. The processing device may be configured to input at least part of the received data to each of the efficiency models. The respective efficiency models may output respective efficiency values for the internal combustion engine and the electric drive. The control unit may control the propulsion system so as to adapt a proportion of the total drive provided by the propulsion system supplied by the electric drive in dependence on the respective efficiency values for the internal combustion engine and the electric drive.

[0099] The model may have different modes that can be implemented by the control unit depending on the intended use of the watercraft. For example, the propulsion system may be controlled for a first part of a journey in dependence on another part of a journey. For example, the propulsion system may be controlled to sustain power of the electric drive and / or fuel levels for the internal combustion engine. For example, if the control unit determines from data indicating the condition of the watercraft and / or its environment that the watercraft has, during a first part of a journey, travelled through a harbour area using the electric drive only, in a second part of the journey (such as a hybrid open-sea journey), the control unit may control the propulsion system to conserve sufficient electrical power (for example, battery power) for use on the return journey to return to the harbour.

[0100] These modes may be pre-programmed or selected by the operator, or may be selected based on data indicating the condition of the watercraft and / or its environment received by the control unit on the outbound route. For example, the model may have a charge-sustaining mode and a charge-depleting mode for the electrical energy source powering the electric drive. The control unit may control the propulsion system to preserve electrical power in dependence on the output of the model.

[0101] The control unit may receive data indicative of a geographical location the watercraft. The data indicative of the geographical location of the watercraft may be input to the model. The control unit may control the propulsion system so as to adapt the proportion of the total drive provided by the propulsion system supplied by the electric drive in dependence on the output of the model.

[0102] Figure 7 shows an example of a method 700 of controlling a drive mechanism for a watercraft. The method is implemented by a one or more processors of the control unit. The method comprises, at step 701 , receiving data indicating a condition of the watercraft or its environment. At step 702, the method comprises, in dependence on the received data, controlling the propulsion system so as to adapt the proportion of total drive provided by propulsion system supplied by the electric drive. In some examples, the method may further comprise inputting the received data to a model. The proportion of the total drive to be provided by the electric drive may be determined in dependence on the output of the model.

[0103] Electric motors powered by batteries are more efficient than internal combustion engines, with high power-to-weight ratios providing torque over a wide speed range. The electric drive may also react more quickly to control signals than the engine. Detecting the condition of the watercraft or its environment and, if appropriate, using a greater proportion of the total drive from the electric drive may therefore allow an operator of the user controls of the watercraft to control speed more accurately or reduce noise or emissions.

[0104] The applicant hereby discloses in isolation each individual feature described herein and any combination of two or more such features, to the extent that such features or combinations are capable of being carried out based on the present specification as a whole in the light of the common general knowledge of a person skilled in the art, irrespective of whether such features or combinations of features solve any problems disclosed herein. The applicant indicates that aspects of the present invention may consist of any such individual feature or combination of features. In view of the foregoing description, it will be evident to a person skilled in the art that various modifications may be made within the scope of the invention.

Claims

AMENDED CLAIMS received by the International Bureau on 5 August 2024 (05.08.2024)1. A control unit for a watercraft propulsion system, the watercraft propulsion system comprising an internal combustion engine and an electric drive, wherein the control unit comprises a processing device configured to: receive data indicating a condition of the watercraft or its environment; input the received data to a model, the model comprising respective efficiency models of the internal combustion engine and the electric drive; and in dependence on the received data, control the propulsion system so as to adapt a proportion of the total drive provided by the propulsion system supplied by the electric drive, wherein the proportion of the total drive to be provided by the electric drive is determined in dependence on the output of the model.

2. The control unit as claimed in claim 1 , wherein, in dependence on the received data, the control unit is configured to adapt a proportion of the total drive provided by the propulsion system supplied by the internal combustion engine.

3. The control unit as claimed in claim 1 or claim 2, wherein in dependence on the received data, the control unit is configured to control the propulsion system such that no drive is supplied by the internal combustion engine.

4. The control unit as claimed in any preceding claim, wherein the propulsion system comprises a hybrid drive assembly and wherein the control unit is configured to send a signal to the hybrid drive assembly to cause a determined proportion of the total drive to be supplied by the electric drive.

5. The control unit as claimed in claim 4, wherein the hybrid drive assembly comprises an electric motor, the electric motor configured to be driven to provide a motor output torque by one or more of the electric drive and an engine output torque of the internal combustion engine.

6. The control unit as claimed in any preceding claim, wherein the electric drive comprises a battery.

7. The control unit as claimed in any preceding claim, wherein the processing device is configured to receive data indicating a condition of the watercraft or its environment from one or more sensing devices.

8. The control unit as claimed in claim 7, wherein the one or more sensing devices comprise one or more of an image sensor, an accelerometer, a gyroscope, a location sensor, a moisture sensor, a freeboard sensor, a fuel level sensor, a proximity sensor, a motion sensor, a pressure sensor, a flow rate sensor, a temperature sensor, a strain gauge, a linear potentiometer and a rotary potentiometer.

9. The control unit as claimed in any preceding claim, wherein the control unit is configured to determine from the received data that the watercraft or a part thereof is in a geographical location and adapt the proportion of the total drive provided by the propulsion system supplied by the electric drive in dependence on the determined geographical location.

10. The control unit as claimed in any preceding claim, wherein the received data provides an indication of a parameter associated with the condition of the watercraft or its environment.11 . The control unit as claimed in claim 10, wherein the control unit is configured to: receive the data associated with a condition of the watercraft or its environment; determine from the received data a value of the parameter associated with the condition of the watercraft or its environment; and adjust the proportion of the total drive supplied by the electric drive in dependence on the value of the parameter.

12. The control unit as claimed in claim 11 , wherein the control unit is further configured to: categorize the value of the parameter into one of a plurality of ranges of the parameter; and adjust the proportion of the total drive supplied by the electric drive in dependence on the one of the plurality of ranges of the parameter.

13. The control unit as claimed in claim 10 or claim 11 , wherein the processing device is configured to adapt the proportion of the total drive provided by the propulsion system to be supplied by the electric drive if the value of the parameter exceeds a predetermined threshold or is below a predetermined threshold.

14. The control unit as claimed in claim 10 or claim 11 , wherein the control unit is configured to cause the electric drive to adjust the proportion of the total drive proportionally or inversely proportionally to the value of the parameter determined from the received data.

15. The control unit as claimed in any preceding claim, wherein the control unit comprises a memory for storing data previously received by the processing device and / or values of parameters determined from the received data.

16. The control unit as claimed in any preceding claim, wherein the received data indicates one or more of: a bank angle of the watercraft, a pitch value of the watercraft, a roll value of the watercraft, a trim of the watercraft, an attitude of the watercraft, an indication of a weather condition, an indication of water conditions, an indication of fuel level, the speed of the watercraft, the efficiency of the watercraft, pilot comfort and a geographical location of the watercraft or a part thereof.

17. The control unit as claimed in any preceding claim, wherein the model is a trained artificial intelligence model.

18. The control unit as claimed in any preceding claim, wherein the control unit is communicatively connectable to one or more user control interfaces, wherein the control unit is further configured to control the propulsion system so as to adapt a proportion of the total drive provided by the propulsion system supplied by the electric drive in response to one or more user inputs to the user control interface(s).

19. The control unit as claimed in any preceding claim, wherein the processing device is configured to: input at least part of the received data to a drag model for the watercraft; anddetermine the proportion of the total drive to be provided by the electric drive in dependence on the output of the drag model.

20. The control unit as claimed in claim 19, wherein the output of the drag model is used as a feedforward control to determine the proportion of the total drive to be provided by the electric drive.21 . The control unit as claimed in claim 19 or claim 20, wherein the input to the drag model comprises a static attitude of the watercraft and the output of the drag model is an estimated mass and / or centre of gravity of the watercraft.

22. A watercraft comprising: a propulsion system comprising an internal combustion engine and an electric drive; and the control unit of any proceeding claim.

23. A method of controlling a propulsion system for a watercraft, the method comprising: receiving data indicating a condition of the watercraft or its environment; input the received data to a model, the model comprising respective efficiency models of the internal combustion engine and the electric drive; and in dependence on the received data, controlling the propulsion system so as to adapt a proportion of the total drive provided by the propulsion system supplied by the electric drive, wherein the proportion of the total drive to be provided by the electric drive is determined in dependence on the output of the model.

24. A computer-readable storage medium have stored thereon computer readable instructions that when executed at a computer system comprising one or more processors cause the one or more processors to perform the method of claim 23.

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