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(11) | EP 3 006 327 A1 |
| (12) | EUROPEAN PATENT APPLICATION |
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| (54) | A control system for a ship |
| (57) The control system comprises at least one propulsion unit, a lever (200) by which
an operator controls the speed and the direction of the at least one propulsion unit
(100), a control circuit (300) controlling the speed and the direction of the at least
one propulsion unit (100) based on the control signals received from the lever (200),
and a force feedback (220) acting on the lever (200). The system comprises further
an algorithm (310) receiving as input signals measured process values (M1) relating
to operational parameters of the ship and the at least one propulsion unit (100).
The control circuit (300) controls the force feedback (220) by comparing the requested
operation received from the lever (200) with safe and/or optimal limits received from
the algorithm (310) in order to transfer haptic information through the lever (200)
to the operator indicating that the requested operation is beyond safe and/or optimal
operational limits of the at least one propulsion unit (100).
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FIELD OF THE INVENTION
[0001] The present invention relates to a control system for a ship according to the preamble of claim 1.
BACKGROUND ART
[0002] Traditionally the speed of a ship was controlled by a telegraph or voice pipes, that relayed the speed setting command from the wheelhouse to the engine room. As the speed of the propeller depend on complex manual operations, the engineer, based on the requested speed, took appropriate actions.
[0003] When the technology developed with the introduction of e.g. diesel engines as prime movers, it became possible to directly control the speed from the wheelhouse. The concept of the telegraph was moved to the new technology, and levers directly controlling the prime mover speed were introduced. These levers moved from a mechanical to a hydraulic and finally to an electronic implementation. The position of the lever is converted into an electronic signal, which controls the propulsion directly or indirectly.
[0004] The steerable rudder propeller i.e. the pod made it possible also to control the direction of the propulsion without a separate rudder. Levers used with a pod move in a longitudinal direction and in a rotational direction combining the speed setting with the direction setting in one multifunctional device.
[0005] The speed and direction settings for the pod should seldom or never exceed certain limits due to physical limitations or safety reasons. The requested propulsion power should as a rule not exceed the power available from the generators which are driven by the diesel engines as an overload of the generators could in worst case stop the diesel engine and render the vessel inoperable. A too high request could also cause disturbances in the electric power supply system that would trigger safety measures. A drop in the frequency of the electric power supply might result in a disconnection of parts of the electric power supply system. There are also limits for turning the pods that should not be exceeded. It should for example not be possible to turn pods so that they come in physical proximity of each other. The thrust vectors of the pods should also follow certain rules in order not to cause damage to the pods. Safeguards to prevent the operator from operating the pods in unsafe combinations and outside safe limits are typically implemented in the control system. The control system will clip the actual control signals to the propulsion system to safe limits in the case the operator requests an unsafe operation. The operator may, however, not be aware that the control system is clipping the requested control, which may cause some confusion and misunderstanding as the propulsion system is not following the lever command as expected.
[0006] There are also other limits that are, not necessarily safety critical and damaging, but related to an inefficient use of the equipment. An inefficient use can e.g. result in poor fuel efficiency or excessive emissions. The requested power may require the diesel engines to be operated at non-optimal conditions. A request for a high output of the diesel engines while the turbo charger pressure is still too low, will result in poor fuel efficiency and a thick black smoke. A speed request may cause high propeller slip and cavitation, or the combination of propeller speed and pitch may be unfavorable from an efficiency point of view. The requested direction of the ship may also lead to high wave forces on the cargo, bring the ship towards unsafe areas or other less desirable states. The operator is typically not made aware of such inefficient, adverse and polluting operation, while it is expected that he by experience would understand good practice and avoid such operation. It is, however, in many cases difficult, even with long experience, to exactly understand the optimal physical parameters for the operation, and the operator will therefore in many cases anyhow operate the ship inefficiently.
[0007] EP patent publication 0 352 257 discloses a control lever with load force feedback. The manually controllable lever is used to steer a bulldozer blade mounted on a track-type tractor having a diesel engine and a transmission interconnected by a torque converter. A sensor feels the movement of the lever and delivers a first signal responsive to the position of the lever. Actuator means applies a force to the lever responsive to the magnitude of a received control signal. There are means for sensing the rotation velocities of the diesel engine and the transmission and for determining the difference between said velocities, whereby said means delivers a second signal responsive to said difference. There are further means for receiving the first and second signals and delivering a control signal to the actuator means in order to control the stiffness of the lever. The actuator means resist the movement of the lever with a force that is proportional to the risk of overloading the tractor. The bigger the risk is the bigger is the resisting force.
[0008] US patent 7,112,107 discloses a throttle control mechanism with haptic feedback. A haptic throttle control mechanism includes a vibrating element that is connected in vibration transmitting relation with the control mechanism. The vibration element can be a motor with an eccentric weight attached to its shaft or a piezo-ceramic component. The vibrating signal can be used to provide information to the operator of the marine vessel relating to the actual operating speed of the engine or, alternatively, it can be used to alert the operator of an alarm situation.
[0009] US patent 5,062,594 discloses a control system for an aircraft or other man-machine system. The usual visual feedback system is optionally supplemented by a secondary feel oriented feedback arrangement in which input signals are derived from either of two supplementary feedback signal sources and the resulting algorithms characterized mathematically. Feedback information to the human operator or pilot is given by way of a tactile or feeling based signal that is coupled to the pilot's joystick.
BRIEF DESCRIPTION OF THE INVENTION
[0011] The control system for a ship according to the invention is characterized by what is stated in the characterizing portion of claim 1.
[0012] The control system for a ship comprises:
at least one propulsion unit comprising a casing being rotatably supported at a hull of a vessel, said casing comprising an electric motor being connected through a shaft to a propeller,
a lever by which an operator controls the speed and the direction of the at least one propulsion unit,
a controller controlling the speed and the direction of the at least one propulsion unit based on the control signals received from the lever,
a force feedback acting on the lever.
[0013] The control system is characterized that it comprises further:
an algorithm receiving as input signals measured process values relating to operational parameters of the ship and the at least one propulsion unit, said algorithm determining safe and/or optimal operational limits for the speed and the direction of the at least one propulsion unit, whereby the control circuit controls the force feedback by comparing the requested operation received from the lever with safe and/or optimal limits received from the algorithm in order to transfer haptic information through the lever to the operator indicating that the requested operation is beyond safe and/or optimal operational limits of the at least one propulsion unit.
[0014] The force feedback gives the operator haptic information through the lever when he is trying to operate the ship in an unsafe manner and/or in an inefficient way. The operator is already at the stage when he is requesting an operation made aware of the fact that the requested operation is either unsafe or non-optimal.
[0015] The lever has a longitudinal control action and/or a rotational action, controlling the speed and/or the direction of the at least one propulsion unit. The lever is equipped with a force feedback, capable of acting on the lever both during the longitudinal and the rotational movement of the lever. The force feedback is controlled based on the commands from the lever and the limits for an unsafe and/or non-optimal operation.
[0016] The force feedback could be a strong continuous force feedback in case the operator is trying to operate the equipment in an unsafe manner. The force feedback could also move the lever back to a safe position when released by the operator, ensuring that the request remains within safe boundaries.
[0017] In case of a non-optimal operation, the force feedback could make the lever vibrate, giving immediate feedback to the operator that the operation requested is not optimal and may cause undesirable consequential effects. The feedback may also be made dependent on how non-optimal the operation is, giving a stronger feedback upon a more non-optimal operation.
[0018] Due to the direct feedback, the operator is made aware of safe and optimal operational limits, which the operator can then take into account in the best possible way. This will improve the efficient operation of the ship, and will reduce unambiguity when trying to operate the ship outside safe boundaries.
BRIEF DESCRIPTION OF THE DRAWINGS
[0019] In the following the invention will be described in greater detail by means of preferred embodiments with reference to the attached drawings, in which:
Figure 1 shows a propulsion unit which can be controlled with the control system according to the invention.
Figure 2 is a block diagram showing the principal of the control system according to the invention.
DETAILED DESCRIPTION OF THE INVENTION
[0020] Figure 1 shows a propulsion unit which can be controlled with the control system according to the invention.
[0021] The propulsion unit 100 comprises a casing 20, a first electric motor 30, a shaft 31 and a propeller 37. The hollow casing 20 comprises an upper portion 21 and a lower portion 22. The upper portion 21 of the casing 20 forms a curved support member for the casing 20. The casing 20 is rotatably supported from the upper portion 21 at a hull 10 of a vessel. A turning wheel 40 is positioned within the hull 10 of the ship. The upper portion 21 of the casing 20 is connected to the turning wheel 40. A pinion 50 is connected to the cogs on the outer surface of the turning wheel 40. The pinion 50 is connected through a shaft 61 to a second electric motor 60. The second electric motor 60 rotates thus the turning wheel 40 and thereby also the casing 20. The casing 20 can thus be rotated 360 degrees by the second electric motor 60 around a vertical centre axis Y in relation to the hull 10 of the vessel.
[0022] The lower portion 22 of the casing 20 has a first end 22A and a second opposite end 22B. The lower portion 22 of the casing 20 forms a longitudinal compartment having a torpedo-shape. The first electric motor 30 is situated within the lower portion 22 of the casing 20. A shaft 31 with an axial centre line X-X passes through the first electric motor 30. The shaft 31 is rotatably supported with bearings 32, 33 in the compartment in the lower portion 22 of the casing 20. The rotor of the first electric motor 30 is attached to the shaft 31 and the stator of the first electric motor 30 surrounds the rotor. A hub 34 is attached to the outer end 31A of the shaft 31 outside the first end 22A of the lower portion 22 of the casing 20 and a propeller 35 is attached to the hub 34. The first electric motor 30 drives the propeller 35 via the shaft 31 and the propeller 35 is pushing the vessel forwards in a first direction S1.
[0023] The first electric motor 30 within the casing 20 is supplied with electric power from at least one generator 80 within the hull 10 of the ship. A diesel motor 70 is driving the at least one generator 80 through a shaft 71. The electric power is transferred to a slip ring arrangement 41 within the turning wheel 40 with a first power cable 36. The electric power is further transferred from the slip ring arrangement 41 to the first electric motor 30 with a second power cable 35.
[0024] Figure 2 is a block diagram showing the principal of the control system according to the invention. The control system consists of a single or multidimensional lever 200 used by the operator to control the at least one propulsion unit 100 of the ship. The position of the lever 200 is transformed to an electrical output signal in a first electric circuit 210 and transmitted further to a control circuit 300. There is further a force feedback 220 connected to the lever 200. The control circuit 300 receives as input signals electric output signals from the first electric circuit 210 and sends control signals C1 to the at least one propulsion unit 100 in order to control the speed and/or the direction of the at least one propulsion unit 100. The control circuit sends also control signals C1 to the diesel engine 70 and the generator 80 in order to control the power of the diesel engine 70 and the magnetization of the generator 80. The control circuit 300 receives also as input signals measured process values M1 relating to operational parameters of the ship and the at least one propulsion unit 100. The process values M1 include at least the rotation speed and the direction of the at least one propulsion unit 100. The process values M1 also include information on the diesel engine 70 and the generator 80. The process values M1 could also include values relating to sea currents, wind speed and direction, wave heights etc. The process values M1 are transferred to an algorithm 310 for determining safe and/or optimal limits for the speed and/or the direction of the at least one propulsion unit 100. The algorithm 310 can be either integrated into the controller 300 or it can be a standalone circuit communicating with the controller 300. The algorithm 310 contains limits for safe and/or optimal operation of the at least one propulsion unit 100. The limits may either be predetermined and fixed, or calculated dynamically based on the measured process values M1. The control circuit 300 controls the force feedback 220 by comparing the requested operation received from the lever 200 with safe and/or optimal limits received from the algorithm 310.
[0025] The lever 200 includes a longitudinal control action for controlling the speed of the at least one propulsion unit 100 and a rotational control action for controlling the direction of the at least one propulsion unit 100. The lever 200 is further equipped with a force feedback 220 capable of moving the lever 200 and/or affecting the movement of the lever 200. This force feedback 220 is applicable on the longitudinal and the rotational movement of the lever 200.
[0026] The force feedback 220 is controlled to act on the lever 200 when the operator attempts to control the at least one propulsion unit 100 in an unsafe and/or non-optimal manner.
[0027] The way of force feedback 220 could be a strong continuous force feedback in case the operator is trying to operate the at least one propulsion unit 100 in an unsafe manner, giving a direct indication of the said. The force feedback 220 could also be made to move the lever 200 back to a safe position when released by the operator, ensuring that the request remains within safe boundaries.
[0028] In case of a non-optimal operation, the force feedback 220 could make the lever 200 vibrate, giving immediate feedback to the operator that the operation requested is not optimal and may cause undesirable consequential effects. The force feedback 220 may also be made dependent on how non-optimal the requested operation is, giving a stronger feedback upon a more non-optimal requested operation.
[0029] Due to the direct force feedback 220, the operator is made aware of safe and optimal operational limits, which he can then be taken into account in the best possible way. This will improve the efficient operation of the ship, and will reduce unambiguity when trying to operate the ship outside safe boundaries.
at least one propulsion unit (100) comprising a casing (20) being rotatably supported at a hull (10) of a vessel, said casing (20) comprising an electric motor (30) being connected through a shaft (31) to a propeller (35),
a lever (200) by which an operator controls the speed and the direction of the at least one propulsion unit (100),
a control circuit (300) controlling the speed and the direction of the at least one propulsion unit (100) based on the control signals received from the lever (200),
a force feedback (220) acting on the lever (200) and being controlled by the control circuit (300),
characterized in that the control system further comprises:an algorithm (310) receiving as input signals measured process values (M1) relating to operational parameters of the ship and the at least one propulsion unit (100), said algorithm (310) determining safe and/or optimal operational limits for the speed and the direction of the at least one propulsion unit (100), whereby the control circuit (300) controls the force feedback (220) by comparing the requested operation received from the lever (200) with safe and/or optimal limits received from the algorithm (310) in order to transfer haptic information through the lever (200) to the operator indicating that the requested operation is beyond safe and/or optimal operational limits of the at least one propulsion unit (100).
at least one propulsion unit (100) comprising a casing (20) being rotatably supported at a hull (10) of a vessel, said casing (20) comprising an electric motor (30) being connected through a shaft (31) to a propeller (35),
a lever (200) by which an operator controls the speed and the direction of the at least one propulsion unit (100),
a control circuit (300) controlling the speed and the direction of the at least one propulsion unit (100) based on the control signals received from the lever (200),
a force feedback (220) acting on the lever (200),
characterized in that the method comprises the steps of:measuring process values (M1) relating to operational parameters of the ship and the at least one propulsion unit (100) and feeding said process values (M1) to an algorithm (310),
determining in the algorithm (310) safe and/or optimal operational limits of the speed and/or the direction of the at least one propulsion unit (100) and feeding the limits to the control circuit (300),
controlling the force feedback (220) with the control circuit (300) in order to give a haptic alert via the lever (200) to the operator when the requested operation is beyond safe and/or optimal operational limits of the at least one propulsion unit (100).
REFERENCES CITED IN THE DESCRIPTION
This list of references cited by the applicant is for the reader's convenience only. It does not form part of the European patent document. Even though great care has been taken in compiling the references, errors or omissions cannot be excluded and the EPO disclaims all liability in this regard.
Patent documents cited in the description