Patent Grant
11124274
The present teachings relate to a gangway for transferring personnel or equipment to or from a vessel.
Gangway operations are frequently used for transferring personnel and goods between floating vessels and other fixed or floating structures. In the wind energy business, gangway transfer is one of the most common ways to transfer personnel, equipment or goods between a service vessel and wind turbines for maintenance tasks. It is also a common way of transferring personnel between offshore floatels and other fixed or floating structures.
In offshore gangway operations, often persons with little or no experience at sea need to be transferred using gangways. An increased comfort and safety is of significant value for the operators. An increase in the operational window of a gangway may not only relax requirements from the operator, but may also reduce the constraints on the conditions in which a vessel and the gangway is allowed to be operated, thereby increasing productivity and availability.
When transferring personnel to or from a vessel and an offshore platform or installation, for example, for commissioning or maintenance of windfarm installations, a gangway is used to bridge the vessel with the installation. The gangway is usually installed on the vessel. Often, the gangway is motion compensated such that the distal end of the gangway has a minimal or ideally no movement relative to the landing point on the installation. The distal end of the gangway may alternatively be called the gangway tip.
One of the challenges in maintaining a safe condition while bridging is to ensure that the gangway tip will not drift or slide off the landing point or area, especially during personnel or cargo transfer. Different methods are possible to ensure such a safe operation. The three main are:
Both in the case of the physical lock principle and the bumper principle, the gangway may be realized as a passive type. In the case of a bumper principle, the acting forces, i.e., the lateral and the vertical forces between the tip and the landing site, should be less than the static frictional force between the tip and the landing site for the frictional coupling to be maintained. Similarly, in the case of the physical lock principle, the acting forces should be less than the relevant mechanical limits such that the physical lock between the gangway tip and the installation remains maintained.
In case of hovering principle, one of the main advantages is that it does not require a specific interface or coupling between the gangway and the platform, however maintaining a minimal movement of the tip relative to a reference point on the installation may be difficult without requiring accurate sensors, actuators and/or control system.
Marine environment can be very dynamic, with environmental conditions such as wind speed, wind direction, waves and marine activity, etc., determining the kind of forces that will be acting on the gangway tip. Moreover, factors such as temperature, precipitation, moisture, surface conditions of the tip as well as the landing site decide the coefficient of friction of contact between the gangway tip and the landing site on the installation. A bumper based system generally sets few requirements with regards to the interface between the tip and the landing site, but there is a risk of the acting forces exceeding the static frictional force between the landing site and the gangway tip, thereby resulting in a non-desired movement of the tip, i.e., a slip or a slide-off of the tip. A combination of said environmental conditions and factors and their variations may make it difficult to decide how much horizontal force would be sufficient for maintaining a stable and reliable contact.
As with a bumper based system, a physical lock based system may also allow for a passive gangway control. Since it does not rely on a frictional coupling as the bumper type does, a physical lock is very suitable for wet conditions, where static friction will be reduced as compared to dry conditions. Moreover, the gangway tip is guided and mechanically held in desired position due to the physical lock. However, a disadvantage of this principle is that it requires the landing site to have an interface that is compatible with the gangway tip such that a physical lock may be established. This may require a specific type of gangway for serving installations where a particular kind of landing mechanism is installed, and thereby restricting the flexibility in serving different kinds of installations using the same service vessel. Additionally, typical realizations of the physical lock result in a step between the gangway and the installation, thereby making it difficult to transfer cargo such as pallets.
At least some of the problems inherent to the prior-art will be shown solved by the features of the present invention as specified in the independent claims.
Further features and combinations consistent with the present teachings will become apparent from the following detailed description of features, which can be combined so as to form further arrangements within the scope of the present disclosure that are not explicitly set out herein.
In this disclosure, the terms distal end of the gangway, distal end of the passageway, tip of the gangway, and tip of the passageway are used interchangeably. Furthermore, the terms walking bridge and passageway are used interchangeably without affecting the scope or generality of the invention.
Example arrangements are described hereinafter with reference to the accompanying drawings. The drawings included in the present disclosure are not necessarily drawn to scale, that being non-limiting to the scope or generality of the inventions disclosed herein.
To further elaborate the luffing movement 140 of the passageway 102 relative and essentially perpendicular to the axis 103 of the pedestal 105, means here that the passageway, with its proximal end 102p attached or connected to the pedestal 105, moves relative to the pedestal 105 such that angle between the axis 103 of the pedestal and the passageway 102 is changed due to said luffing movement 140 of the passageway. Similar comments apply also to the tilt movement 120 of the pedestal. Further, by linear movement 150 for adjusting the linear distance between the proximal end and the distal end of the passageway 102, it is meant that the two sections 102a and 102b of the passageway or walking bridge can be extended or retracted with respect to each other.
The heave 130 can either be achieved, for example, by an extendible pedestal, such as a telescopic type pedestal, or due to a passageway arrangement that can traverse vertically along the pedestal 105. By the passageway arrangement that can traverse vertically along the pedestal, it is meant that the proximal end 102p of the passageway 102 is capable of being moved and positioned vertically, along the axis 103 of the pedestal 105.
Three degrees of freedom are needed to position the distal end 102d of the passageway 102 at a given target position. The given target position can be a three dimensional location on a coordinate system with respect to a reference point, the reference point being fixed or variable with respect to the coordinate system.
A person skilled in the art will appreciate that different types of movements defined above can be realized using either or a combination of mechanical arrangements such as hydraulic, pneumatic or electric actuators, cable and winch mechanisms, gear box, or such. It should also be understood that the extension and retraction of the passageway 102 can be achieved, for example, by a telescopic type passageway, or even a lazy-tongs type structure. The passageway 102 may even have more than two sections. A particular choice of a mechanical arrangement or a structure limits neither the scope nor the generality of the present invention. These various degrees of freedom, or joints can be used for compensating undesired movements induced for example by environmental disturbances, as a result holding the gangway substantially stationary with respect to a reference point.
Now referring to
According to another aspect of the present teachings, a feedback loop is used to regulate the predetermined transversal force. Accordingly, the movement caused in the wheel is measured using at least one sensor used for calculating the force with which the wheel is to be pushed towards the landing site. The at least one sensor may be a force sensor and/or it may be a position sensor measuring a position or displacement of/in a mechanism that provides the transversal movement 150. Various possible realizations of the mechanism have been discussed earlier, i.e., it may be prismatic joint or any other kinds of alternatives or their combination. Alternatively or in addition, the at least one sensor may be located in the wheel unit 310. When located in the wheel unit, the at least one sensor may measure the transversal force and/or a position/displacement indicative of the transversal force.
According to another aspect, the wheel unit 310 may be operatively coupled to a position sensor such as a rotary encoder or such for sensing a position of the wheel 315. Alternatively or additionally, the wheel unit 310 may be operatively coupled to a velocity sensor for sensing a velocity of the wheel 315. Alternatively or additionally, the wheel unit 310 may be operatively coupled to a force sensor for sensing a force related to or acting on the wheel 315. Alternatively or additionally, the wheel unit 310 may be operatively coupled an actuator, the actuator being used for effecting a movement the wheel 315. Said effecting of a rotation of the wheel 315 means that the wheel 315 is driven by the actuator, for example, to position the wheel unit at or close to a specific position relative to a reference point. Said reference point may be any fixed point on earth. Alternatively, the reference point may be a point on the installation where the gangway with the wheel unit 310 is to be deployed, for example, for a case where the installation is a floating installation. In such cases, it may be desirable to hold the gangway substantially stationary with respect to the floating installation rather than with respect to a fixed point on earth. It would be obvious to the skilled person that for fixed installations, the reference point anywhere on earth also includes a reference point on the fixed installation. When the actuator, shown here as a rotatable element actuator 320, is an electrical actuator such as an electrical motor, the wheel unit 310 may also include a sensor for measuring current or power to the motor. According to another aspect, the electrical motor may be a stepper motor or such where the displacement of the rotor may be accurately effected by sending a pre-determined drive signal to such a motor. The stepper motor may be a rotary type or a linear type stepper motor.
An output from the position sensor, or any other sensor provided to output an output signal dependent upon the position of the distal end, may be input to a processing unit. The processing unit may compare the output of the sensor with a predetermined reference signal to generate an error signal. As will be understood, the predetermined reference signal here represents a desired position of the distal end. Accordingly, the error signal output from the processing unit can be used to effect a movement in the distal end such that the distal end is aligned substantially at or close to the desired position. By substantially aligned means here that the distal end location is within acceptable tolerance for a successful alignment with the desired position such that an actuator effecting the movement may stop driving the distal end further. If the sensor includes a processing unit, the sensor may provide an output signal dependent upon the position of the distal end with respect the desired position. In some cases, the output signal of the sensor may even be dependent upon to the movement of the rotatable element, e.g., in cases when the position of the distal end is measured with respect to the movement of the rotatable element.
It will be understood that the processing unit can be a module such as a computer processor. The processing unit can be any type of computer processor, such as a DSP, an FPGA, or an ASIC. The processing unit may further comprise a machine learning module. The processing unit may also comprise an artificial intelligent processor. The processing unit may a separate module, or it may even be a part of any of the controllers discussed herein, e.g., DP system controller, gangway controller, end effector unit controller, slew controller, and such. It will further be understood that in some cases the processing unit may be a non-electric module, i.e., based on signals that are not electrical. A skilled person will understand that non-electric controllers also exist in the field of art, such as pneumatic, and hydraulic controllers. Moreover, a combination of non-electric and electric controllers may also be possible.
The movement in the distal end may be effected using the rotatable element actuator 320, or it may be effected using a slew actuator, or it may be effected using a dynamic positioning (“DP”) system, or even any combination of these. This and other operating modes will be discussed later in this disclosure.
In
As already discussed, the installation may either be a fixed installation or a non-fixed installation, such as a floating installation. Alternatively or additionally, the wheel unit may be operatively coupled to an anti-slip system. The anti-slip system may use at least one sensor operatively coupled to the wheel unit 310 to detect a slip condition at the distal end 120d. According to another aspect, the anti-slip system may then use an actuator to reposition the wheel unit or the distal end at or close to the previous position where the wheel unit or distal end was prior to the occurrence of the slip condition. Alternative to the wheel unit being operatively coupled to various sensors, actuator(s) and system(s) discussed above; at least some of the various sensors, actuator(s) and system(s) discussed above may be comprised within the wheel unit 310.
According to an aspect, the wheel unit 310 is used to sense and control the motion of the gangway, especially the motion of the distal end 102d. When deployed towards an installation, a frictional force will exist between the wheel 315 and the landing surface on the installation due to the wheel 315 being pushed against the landing surface with a transversal force. When a torque is applied to the wheel 315, a lateral force will be exerted on the gangway. In case the wheel 315 is of the types mounted on a fork with ability to rotate around the x-axis as described above, or if the wheel 315 is of omni-wheel type, the force exerted on the gangway may comprise both lateral and vertical components.
According to an aspect, the gangway with additional actuators, such as actuator(s) for effecting slew movements 110 in the pedestal, and the wheel unit 310 is controllable by a gangway control system such that the control system can control both the slew movement 110 and the rotation 312 of the wheel 315 for controlling the overall horizontal movements of the gangway system. The slew movement may be controlled by a slew controller. The slew controller may be a separate controller or a part or module of the gangway control system. Similarly, the rotation of the wheel 315 may be controlled by a position controller. The position controller may be a separate controller or a part or module of the gangway control system. By overall horizontal movements, it is meant the movements along the y-axis. Accordingly, the gangway control system may control the slew movement 110 to effect a coarse adjustment, whereas the rotational movement 312 of the wheel 315 to effect a fine adjustment of the gangway position with respect to a reference point. Alternatively, or in addition, correction for slow movements may be effected by the control of the slew movement 110, whereas correction for fast movements may be effected by the rotational movement 312 of the wheel 315. From an environmental context, the slow movements or slow dynamics may be considered as those corresponding to a steady-state wind force, whereas the fast movements or fast dynamics may be considered as those corresponding to gusts in the wind force. The gangway can thus perform at least two control functions, first, for slew control, by measuring a lateral force acting between the distal end 102d and the landing site for generating a measured lateral force value. A signal dependent on the measured lateral force value is fed to the slew controller for minimizing the lateral force at the distal end 102d. By doing so, the amount of undesired lateral force acting on the passageway may be at least substantially reduced. The undesired lateral force can be generated, for example, due to winds or other environmental factors. In the second function, the wheel 315 may be rotated, for example, by the position controller, for positioning the distal end 102d at the desired position. Accordingly, the slew controller and the wheel controller collaborate to position the distal end 102d substantially close to the desired location.
According to another aspect, the wheel unit 310 may comprise a wheel unit controller rather than the wheel unit 310 being directly handled by the gangway control system. The gangway control system may then work together with the wheel unit controller to realize at least some of the functions explained above. The wheel unit controller may be a separate controller or a module within the gangway control system.
According to another aspect, the wheel unit 310 is used to measure the torque on the wheel 315, for example, by using a force or torque sensor. The measurement may be continuous or intermittent. When the wheel 315 is not being driven by an actuator, the torque on the wheel 315 is indicative of the lateral force acting between the installation and the distal end 102d. The wheel torque may thus be used for implementing the slew control as described above, for example, by using the wheel torque as, or to generate, a signal dependent on the measured lateral force value to be fed to the slew controller. In cases where the wheel 315 is driven by an actuator, a torque value indicative of the lateral force may be calculated by subtracting the force or torque applied by the actuator for driving the wheel 315 from the overall torque measured at the wheel 315. Accordingly, it is possible to extract the lateral force value for driven and not driven applications. Furthermore, for performing such calculations, a model of the system may be used.
Alternatively or in addition, the wheel unit 310 also the measures the position of the wheel 315. When the gangway is deployed and the wheel 315 is in contact with the landing surface on the installation with a pre-determined force, the wheel controller may be used to drive the wheel 315 such that the distal end 102d aligns to a desired position on the landing surface. Said driving of the distal end 102d may either be right after deployment of the gangway to the installation, or even be in real-time, to counteract the external forces. The examples of the external forces have been given earlier, which may be marine activity, winds or other environmental phenomena. Accordingly, the operational window of the gangway operation may be increased, and the scenarios with need for reconnecting to position the gangway may be minimized. Alternatively, if the wheel unit 310 does not have a dedicated wheel controller, said driving may be done by the gangway controller or another control system. The torque sensor may be a separate sensor, or it could be integrated within the actuator 320 or motor for driving the wheel 310. As explained previously, environment dependent forces, such as wind force, are substantially compensated by driving the slew actuator (e.g., driven by the slew controller), where the wheel 310 may be used as a lateral force sensor. This may at least substantially reduce the probability of a slip condition.
By “the scenarios with need for reconnecting” mentioned above, it is meant unexpected slip conditions. For any unexpected slip conditions, as an additional safety measure, if a slip has indeed occurred, for example, by a strong wind gust or such, and where such a slip condition may have moved the distal end 102d to an undesired position, the position control is used to reposition the distal end 102d back to the desired position. A secondary position sensor or measurement may be used to assist for such repositioning.
The rotational end effector has been realized as a wheel unit 310. In a top-view of the gangway 440 shown in
In
The wheel may be driven by an actuator 320 such as a motor operatively coupled to the wheel 315 through a coupling system 325. The coupling system 325 that is shown realized in this example is a belt or chain type system. Alternatively, the coupling system could have been any of the other types as explained earlier. At the point 402 at which the wheel 315 is in contact with the landing surface 401 of the receiving structure or installation 400, may be termed the tip of the gangway. Only a small portion of the receiving structure 400 is shown, just as an example, with no specific limitation on the shape of the installation. As can be understood from the earlier discussion, the tip is at the distal end 102d of the gangway 440. The contact point 402, in practical cases will be a contact area due to resilient nature of at least the outer surface of the wheel and due to a transversal force applied to force the wheel 315 towards the contact point or area 402. Thus is practical cases there will be some deformation or flattening of at least some of the resilient portion of the wheel 315 along the installation surface 401, due to which the contact point 402 may actually be a contact area. However, for ease of discussions, the contact area, may be considered as a contact point 402 herein without affecting the scope or generality of the invention. At the contact point 402, a lateral force 418 is shown acting between the surface 401 of the installation and the wheel 315. The direction of the lateral force 418 is shown purely for illustrative purposes in
According to another aspect, the secondary position sensor 416 is used for aligning the distal end 102d of the gangway 440 with respect to a reference point. The secondary position sensor 416 may be a camera providing a 2D or 3D image of the target or any other kind of position tracking sensor. According to another aspect, the secondary position sensor 416 may track the position by using a pre-determined pattern 417 attached close to the landing area such that the wheel 315 may be aligned at or substantially close to a desired point 402 on the installation 400. Alternatively, when the secondary position sensor 416 is a camera, the camera may generate its own reference pattern, for example, by taking a picture of at least a portion of the installation 400, and then using the picture to align the wheel 315 to the target point 402. Based upon a database of pictures of various installations and desired landing points, the camera may take real-time pictures to automatically control the deployment of the gangway to an installation. According to another aspect, the secondary position sensor 416 may be a stereoscopic sensor providing three-dimensional information for the target. For example, if the secondary position sensor 416 is a camera, the camera may be a stereoscopic camera to provide three-dimensional target information. A stereoscopic camera can be used to provide a target less image acquisition. Target less image acquisition meaning that no predefined information may be needed regarding the landing structure to be able to deploy the gangway.
An example of the landing process using a camera as a secondary position sensor is illustrated in
When the camera 416 takes over, the camera 416 detects the position of the target point 402, which then represents the global position reference. The camera provides the data to a forward kinetic unit 450, which also, preferably, received information about the actuator and joints controlling the gangway movement.
Based on the position of the base P_B and target point P_ref the necessary movement is found P_B_Ref from the base to the reference point on the target, and in an inverse kinematic unit 460 the joint coordinates q_Ref necessary to reach the target is calculated. This is translated 465 into control signals a_Ref for the actuator 470 which moves the joints 475 into correct positions. As stated above the status and position of the actuator a and joints q may be measured by suitable sensors or actuator drivers and transmitted 480 back into the forward kinetics unit 450. Depending on the camera capabilities, at least some of these data may alternatively be retrieved by analyzing the images obtained by the camera 416.
This way the embodiment of the invention incorporating a camera based reference system for moving the gangway the system may be fully automatic when landing a gangway on an offshore wind turbine or similar structures.
After the gangway 440 has been deployed, the secondary position sensor 416 may also be used to detect a slip or drift in the wheel 315 with respect to the desired landing point 402. Such a drift or slip may be as a result of the disturbances caused by the environmental conditions. Other variations of the secondary position sensor 416 may be, ultrasonic sensor, reflective sensor using laser or other light source, or the secondary position sensor 416 may even be a secondary wheel. Alternatively or in addition, the control of deployment may be done or assisted by an operator of the gangway 440. A skilled person will understand that a use of the secondary position sensor 416 and/or the pattern 417 is option with respect to the rest of the functionality explained in
Without a secondary position sensor 416, a position sensor in the wheel unit may be used to detect a drift. Such a position sensor may measure a rotational position representative of the rotation of the wheel 315.
Now referring to
Various actuators for effecting various movements in the gangway 440 are controlled either directly or indirectly by a gangway control system. The gangway control system will also receive a plurality of sensor inputs. Such sensor inputs may be from position sensors, force sensors, velocity sensors, associated with at least some of the various degrees of freedom in the gangway 440.
According to another aspect, the actuator 320 uses feedback control. The feedback control may include one or more operational modes. In a first operational mode, the actuator 320 will run with torque control to limit the possibility of slipping. In addition, another feedback from a secondary position sensor may be used to position the tip at the desired landing point. In addition to the feedback control, the control system, as separate controller or integrated, may include a cascade controller for the slew actuator and the wheel actuator for controlling either one or any of the following related to the slew actuator and the end effector respectively: position, velocity, force and torque. In such a control structure, the slew control loop slew may control torque, with feedback from the wheel unit. Whereas the wheel actuator controls speed and position of the distal end.
According to an aspect, the wheel unit 310 also comprises a locking device for preventing an undesired rotation of the wheel 310 along the rotational axis 311. The locking device may be a brake, for example, a mechanical brake, or an electrical brake, or their combinations. The locking device may act either on the wheel 315, or the coupling means 325, or the actuator 320, or even their combinations. According to another aspect, the locking device may be integrated in the actuator 320. When using a gearbox, drivetrain or gear train type coupling system 325, depending upon the conversion ratio, such locking means may even be redundant. For example due to high conversion ratio between the actuator 320 and the wheel 315, it might only be possible to induce rotations in the wheel 315 by rotating the actuator 320, and not the other way around. Alternatively, the locking device may be a ratchet type locking unit within the gearbox or gear train.
When the wheel 315 is in contact and locked in at the desired contact point 402, as long as the lateral force 418 acting at the contact point 402 of the wheel 315 does not exceed the frictional force, the wheel 315 and hence the distal end 102d will be retained in the desired position. A lateral force greater than the frictional force will lead to an acceleration of the gangway 440 in the slew direction 110. The frictional force may be increased, for example, by increasing the transversal force 408.
Based upon how the above-mentioned teachings are configured, the following operational cases may be used,
Non-Driven Wheel:
The wheel 315 is not driven by the actuator 320, i.e., the actuator 320 is either absent or is not used. The wheel unit 310 may still comprise at least one sensor, for example a position sensor for measuring the rotational position of the wheel. In such a case, the slew movement 110 generated by a slew actuator may used to position the gangway towards the desired point 401 on the installation 400. The slew actuator may, for example, be placed in or close to the gangway base 406. The slew actuator rotates the pedestal 105 relative to the gangway base 406. A condition of contact of the wheel with the surface 401 of the installation 400 is detected by using a force sensor measuring the transversal force 408. The transversal force 408 may be adjusted to have sufficient frictional coupling between the wheel 315 and the surface 401. The wheel 315 then rolls on the surface 401 in y-direction due to slew movements 110 by the slew actuator until the wheel 315 is sufficiently close to the desired contact point 402. As understood, for aligning the gangway, rather than measuring the position of the wheel with respect to the desired contact point 402, the position of the distal end 102d with respect to a corresponding desired reference point may also be measured. The alignment may be done, for example, by using a secondary position sensor 416. Alternatively or in addition, the alignment may be done by or assisted by an operator. When alignment is satisfactory, the gangway may be locked into position, for example by locking the slew actuator. Alternatively or in addition, the wheel 315 may be locked in position, as explained earlier. As and if the wheel slips or drifts, the slew actuator is activated to drive the distal end 102d back into position. Provided that the transversal force maintains contact of the wheel 315 with the surface 401, the wheel 315 will then roll back towards the desired landing point 402 due to slew movements 110 generated by the slew actuator. The gangway control system can additionally control the various actuators of the gangway 440 for compensating the environmental disturbances such that the gangway remains substantially stationary with respect to the installation 400. An advantage of such an approach can be that the gangway 440 always remains in contact with the installation, and the control system is able to manipulate at least the movement of the gangway 440 along the y-axis even when the gangway is in contact with the installation 400.
Driven Wheel:
In this case, unlike the non-driven case, the wheel 315 can also be driven by the actuator 320. In such a case, for example, the slew actuator may be used to do a coarse alignment of the distal end towards a desired landing site or a reference point. The wheel 315 is then landed on the surface 401 of the installation. A contact is detected by measuring the transversal force 408, the wheel 315 is then driven using the actuator 320 for a fine alignment of the wheel with the desired landing point 402. As understood, for aligning the gangway, rather than measuring the position of the wheel with respect to the desired contact point 402, the position of the distal end 102d with respect to a corresponding desired reference point may also be measured. The alignment may be done, for example, by using a secondary position sensor 416. Alternatively or in addition, the alignment may be done by or assisted by an operator. When alignment is satisfactory, the gangway may be locked into position, for example by locking the wheel unit actuator 320. Alternatively or in addition, the wheel 315 may be locked in position, as explained earlier. As and if the wheel slips or drifts, the wheel unit actuator 320 is activated to drive the distal end 102d back into position. Provided that the transversal force maintains contact of the wheel 315 with the surface 401, the wheel 315 will then roll back towards the desired landing point 402 due to rotational movement 312 generated by the wheel unit actuator 320. The gangway control system can additionally control the various actuators of the gangway 440, including the wheel unit actuator 320, for compensating the environmental disturbances such that the gangway remains substantially stationary with respect to the installation 400. An advantage of such an approach can be that at least some of the disturbances are compensated using the wheel actuator 320, which is a relatively smaller system and typically faster to react as compared to the case where slew actuator and the gangway 440 have to be moved to compensate the disturbances. The compensation using the wheel unit actuator 320 may have a significantly smaller time constant as compared to that of the non-driven case, may enable the compensation of faster disturbances as well as better stability of a closed-loop system. Alternatively or in addition, the wheel unit actuator 320 will usually experience different dynamics as compared to what the slew actuator will experience because the wheel unit actuator 320 is placed closer to the point (i.e., the distal end 102d) being positioned or controlled. As will be appreciated, in the gangway system aspect, the slew actuator based control or slew dynamics may be characterized as a non-minimum phase system, at least because of the bending of the passageway. Non-minimum phase systems have physical limitations for achievable performance and stability. According to the present teachings, an end effector and/or a measuring unit located in close proximity to the landing site, brings the gangway system to a minimum phase system. Hence, a faster feedback control dynamics may be achieved. By effecting position control of the distal end 102d using the wheel unit 310 unwanted dynamics of the system such as flexing of the gangway arm 102 may be reduced or eliminated from the transfer function of the system. Such unwanted dynamics would normally appear in the gangway system transfer function, for example if the movements are effected using the slew actuator rather than the wheel unit actuator. Similarly, at least some distal end measurements, such as measuring drift of the distal end, when done with a sensor located closer to the distal end 102d will have advantage as compared to measurements done at the gangway pedestal or base.
It will be appreciated that each of the non-driven wheel mode and the driven wheel mode discussed above is novel and inventive in its own right, besides a combination of these modes being novel and inventive.
According to another aspect, the gangway control system may allocate compensation between the slew actuator and the wheel actuator 320, based for example on slow and fast disturbances respectively. As also discussed previously, from an environmental context, the slow disturbances or slow dynamics may be considered as those corresponding to a steady-state wind force, whereas the fast disturbances or fast dynamics may be considered as those corresponding to gusts in the wind force. According to another aspect, the when unit 310 may also comprise a wheel unit controller. The gangway control system may then communicate and if required, control the wheel 315 through the wheel unit controller.
According to another aspect, the slew controller goes from active mode (i.e., driven mode) to a passive mode (i.e., switched-off mode) as soon as a contact between the wheel 315 and the surface 401 is detected. In such a case, the control of the distal end 102d movement along the y-axis is done only using the wheel actuator 320.
Irrespective of the driven or non-driven case above, it will be appreciated that the proposed teachings in general can allow for achieving an accurate alignment without the need for removing and reconnecting the gangway distal end 102d from the installation 400, should it be a case that in a first try the gangway did not contact the installation 400 close to the desired position. Furthermore, the non-driven case may be an operational mode of the gangway system that also can operate in the driven case.
From the preceding discussion, the present teachings can thus be used for:
A. Reducing a Risk of the Gangway Sliding Off the Installation:
This can be done, for example, by measuring the acting transversal force 408, and using a slew controller driving the slew actuator and hence rotating the pedestal 105 with respect to the gangway base 406 to minimize the lateral force 418 acting at the distal end or tip 102d.
Avoiding a slip condition by using the wheel unit 310 in an anti-slip mode. This can for example be done by limiting the wheel torque. One way to estimate maximum wheel torque is calculate the maximum torque for a given frictional force. The system can then limit the torque below this value to minimize the chances for a slip condition when the wheel 315 is driven. According to another aspect, this functionality may also be used as an active damping mode instead of the locking in of the wheel 315 discussed before. The wheel 315 is thus not locked, but configured as an active damper. The wheel 315 is thus allowed to move and but motion will be dampened. This mode may be useful in conditions where large variations in the lateral force 418 are expected such that a slip condition are likely. By configuring the wheel unit 310 in an active damping mode, the likelihood of slip can be at least substantially reduced. Even though the wheel is allowed to drift, it is subsequently rolled back at or close to the desired position 402. The main objective of the anti-slip mode is to prevent sudden loss of contact due to slip caused by large lateral forces, and rather let the wheel drift as a result of such large lateral forces and subsequently correct the drift. By doing to, stability and safety of the gangway may be enhanced.
B. Increasing Safety:
By estimating a friction force, calculated based upon the friction between the wheel 315 and the landing surface 401 as a first estimate, for example by using the measured Transversal force. Alternatively, the wheel unit 310 may create an exploratory contact with the landing surface and measure the transversal force 408 and the lateral force 418 at which the wheel 315 starts slipping on the surface 401. Said lateral force may be induced for example by the slew actuator. Based upon said exploratory contact, a value of the frictional coefficient may be estimated. In either case, whether the frictional force is calculated using a pre-determined frictional coefficient or being measured by an exploratory contact, the system can indicate if a slide-off or slip is likely for prevailing conditions.
In case a slide-off or slip has occurred. The system detects such a condition, for example by using a secondary position sensor 416 as discussed previously.
C. A safer and easier method to correct the distal end or tip 102d position whilst maintaining a transversal force towards the platform.
If the distal end 102d of the gangway 440 did not land at or close to a desired landing position, the distal end 102d may not be required to disconnect from the installation 400 and reconnect to adjust the tip 102d position.
A control of the distal end 102d is achieved by rotation of the end effector wheel 315, while maintaining a transversal force pushing the distal end 102d towards a landing structure 400.
With a conventional static rubber bumper stiction and/or friction forces will prevent such a functionality with a slew actuator.
According to the teachings presented herein, a typical operational scenario in such case could be:
The above scenario is similar to the driven wheel case discussed previously. Alternatively to the slew actuator being in passive mode, the functionality similar to that of the non-driven case may be used, i.e., the slew controller or gangway controller is used to minimize the lateral force 418 on the wheel 315 by rotating the gangway using the slew actuator.
Thus, according to an aspect the gangway is operated in a coordinated control mode in which the slew actuator and the rotatable element actuator are configured to operate in a control mode in which said actuators coordinatively effect the movement in the distal end. The coordinated control mode may be any of the: passive mode, headroom passive mode, and assisted mode as discussed above.
If the lateral force value is substantially equal to the desired lateral force value, the controller moves further to step 605. If the lateral force value is not equal to the desired lateral force value, then the controller moves to step 604 and drives the slew actuator to make adjustments or corrections to the slew actuator such that a slew movement is effected, while comparing resulting measured lateral force values with the desired lateral force value, until the measured lateral force becomes substantially equal to the desired lateral force value. The controller hence tries to minimize the difference between the measured lateral force value and the desired lateral force value. In step 605, the controller checks if the LFC should be terminated. If yes, the LFC is terminated. If not, the LFC starts again at step 602.
Now certain non-limiting examples related to the end-effector unit will be discussed. The non-limited examples may be combined with any of the variations of the present teachings. In previous examples the rotatable element was shown as a wheel 315. As will be appreciated, a diameter of the wheel 315 can be selected based upon application and within the constraints of what is practically and economically feasible. In some embodiments, the diameter of the wheel is between 0.01 m-10 m. In other embodiments, the wheel diameter is between 0.1 m and 1 m. In some embodiments, the wheel diameter is between 0.3 m and 0.7 m. In certain embodiments, the wheel diameter within the range of automotive wheel sizes is preferable. In some embodiments, an automotive wheel is used as a wheel of the end effector unit.
With reference to
According to another aspect of the wheel-belt system, the rotatable element 315 may be a plurality of elements, or wheels. For example, as shown in
With reference to
It may be noted that an end effector with a type of arrangement as shown in
At least the outer surface of the ball 1315 is resilient material such as discussed previously.
The shafts 1311 and 1322 are held in position by bearing posts 1376 or such fixing means. The shafts 1311 and 1312 have driving portions 1341 and 1342 for relatively translating movement of the respective shafts into a movement of the ball 1315. Each driving portion 1341 and 1341 is designed such that it essentially freely allows for the movement in the ball due to a rotation of the other shaft. The shafts may either be driven directly through their respective actuators, or the shafts may be coupled through coupling means 1381 and 1382 to their respective actuators. Alternatively or in addition, the coupling means may comprise at least one sensor.
As will be appreciated, a ball type end effector may allow effecting both horizontal and well as vertical movements, and a combination of those, of the distal end 102d. Accordingly, a vertical position of the distal end 102d may be adjusted without disconnecting the gangway from the installation.
According to another aspect, for effecting both horizontal and well as vertical movements and a combination of those, an omni-wheel is used as end effector. The omni-wheel is a wheel that is capable of effecting movements in a plurality of axes. The omni-wheel is not discussed further in this disclosure as the term will be known to the skilled person.
Vertical movements may also be effected in a wheel based end effector, which is discussed in the following. According to another aspect, the rotatable element can be mounted in a rotatable mechanism, the rotatable mechanism being capable of altering an angle between an axis of rotation of the rotatable element and the axis 103 of the pedestal or base of the gangway. With reference to
In
In
To summarize, the present teachings relate to a gangway comprising a distal end on which an end effector unit is attached,
the end effector unit having an outer surface at least a certain portion of which is adapted to be in contact with an installation, wherein
a movement of a rotatable element in the end effector unit corresponds to a movement of the distal end with respect to a reference point on the installation when the end effector unit is in contact with the installation, the movement of the distal end being at least along one of the axes related to the installation.
Present teachings also relate to a gangway comprising a distal end on which an end effector unit is attached. The end effector is having an outer surface at least a certain portion of which is configured to be in contact with an installation. The end effector unit also comprises a sensor. A movement of a rotatable element in the end effector unit corresponds to a movement of the distal end with respect to a reference point on the installation when the end effector unit is in contact with the installation. The movement of the distal end is at least along one of the axes related to the installation. The sensor is configured to provide at least one output signal dependent upon the position of the distal end with respect to the reference point. The gangway is also operatively linked to an actuator. The actuator is configured to effect movement in the distal end for positioning the distal end at least substantially close to a desired location on the installation.
The gangway may be installed on a vessel or it may be installed on a fixed structure. The installation may either be a fixed structure offshore or on land, or the installation may be a floating vessel or structure.
According to an embodiment, the rotatable element is a wheel. In which case, the movement of the rotatable element is rotation of the wheel. According to another embodiment, the rotatable element is a semi-wheel. The wheel may even be an omni-wheel.
According to yet another embodiment, the rotatable element is essentially spherical, such as a ball. In which case, the movement of the rotatable element is a rotation of the spherical rotatable element.
According to an embodiment, at least one of the at least one output signal of the sensor is dependent upon to the movement of the rotatable element.
According to another embodiment, the rotatable element is mounted in a rotatable mechanism, said rotatable mechanism being adapted to alter an axis of rotation of the rotatable element with respect to an axis of the base of the gangway.
According to another embodiment, the rotatable element is a wheel-belt system. The wheel-belt system comprises at least one wheel operatively coupled to a belt. The belt forms at least some of the outer surface of the rotatable unit, a certain portion of which is adapted to be in contact with the installation. According to another embodiment, the wheel-belt system comprises a plurality of wheels.
According to another embodiment, the rotatable element is coupled to a force sensor, the force sensor being configured to measure a force with which the rotatable element is pushed against the installation. The force sensor is adapted to measure at least one force acting between the installation and the end effector unit. In other words, the force sensor is configured to output a force signal indicative of the force with which the rotatable element is pushed against the installation. It will be understood that the force signal may be an electrical output signal indicative of the force, and/or it may a non-electrical signal, depending upon the type of sensor used. It will be appreciated that non-electrical sensors also exist, further details of which is not pertinent to the scope or generality of this disclosure.
According to another embodiment, the rotatable element is coupled to a position sensor, the position sensor being configured to measure a position of the rotatable element with respect to a reference point. In other words, the position sensor is configured to output a position signal indicative of the position of the rotatable element with respect to a position reference point. Similarly, it will be understood that the position signal may be an electrical output signal indicative of the position, and/or it may a non-electrical signal, depending upon the type of sensor used.
According to another embodiment, the rotatable element is coupled to a velocity sensor, the velocity sensor being configured to measure a velocity related to a rotation of the rotatable element. In other words, the velocity sensor is configured to output a velocity signal indicative of the velocity related to the rotation of the rotatable element. Similarly, here also it will be understood that the velocity signal may be an electrical output signal indicative of the velocity, and/or it may a non-electrical signal, depending upon the type of sensor used.
The actuator may be a slew actuator of the gangway, and/or it may be an actuator controlled by the DP system. The actuator may even be one or more thruster or a propeller or similar actuators controlled by the DP system.
According to another embodiment, the end effector unit also comprises an actuator, or the actuator discussed above is a rotatable element actuator. When the end effector unit is in contact with the installation, the rotatable element actuator is configured to effect movement in the rotatable element for positioning the distal end at least substantially close to a desired location on the installation. The end effector unit may even comprise a plurality of actuators. The end effector unit may even be retracted from the distal end using at least one of the plurality of actuators.
The gangway may further comprise a slew actuator. The gangway may be configured to operate in a coordinated control mode in which the slew actuator and the rotatable element actuator are configured to operate in a control mode in which said actuators coordinatively effect the movement in the distal end. By coordinatively effecting the movement, it is meant one or more of the actuators operating: simultaneously, sequentially, or one of the actuators being disengaged thus offering minimum hindrance to the other actuator from effecting the movement.
The control mode can be a full passive mode as discussed previously. In the passive mode, the slew actuator is configured to disengage from driving the distal end. In this mode the slew actuator is also prevented from retaining or locking the distal end at a given position, hence offering minimum hindrance to the rotatable element actuator from effecting the movement.
The control mode may even be a headroom passive mode as discussed previously. In this mode, the slew actuator is configured to disengage between a predetermined movement range of the distal end. In other words, the slew actuator offers minimum hindrance to the rotatable element actuator from effecting the movement within a predetermined range of the movement of the distal end. This mode can be helpful in locking the distal end from further movement beyond one or more predetermined limits. This can be beneficial, e.g., for preventing the distal end from drifting beyond the limits within which the rotatable element actuator can effect the movement for aligning the distal end substantially close to the desired position.
The control mode may even be an assisted mode as discussed previously. In this mode the slew actuator is configured assist the rotatable element actuator for effecting the movement in the distal end.
The end effector unit is configured to be in contact with the installation with a predetermined transversal force. A controller or a control system is used to regulate the predetermined transversal force. The controller may be a separate controller, or end effector unit controller, or integrated with the gangway controller. Alternatively in cases where the gangway is mounted on a vessel, the whole vessel may be controlled by an integrated controller with respective controllers being sub-controllers or even software modules within the integrated controller. The predetermined transversal force is calculated based upon at least some of the system parameters including, any one or more parameters from: prevailing environmental conditions or factors, properties of the installation surface, and properties of the outer surface, etc.
A landing site on the installation may be selected based upon the at least one of the parameters related to the prevailing environmental conditions or factors. A desired location may be found where the influence of the prevailing environmental conditions on the vessel or the gangway is deemed to be minimal.
According to another embodiment, when the end effector unit is in contact with the installation, the slew controller of the gangway is configured to at least partially minimize a lateral force acting between the distal end and the installation. The slew controller is functionally or operably connected to the slew actuator.
In an embodiment, the end effector unit is operatively coupled to an anti-slip system. The anti-slip system comprises or is controlled by an anti-slip controller receiving input from at least one sensor. The anti-slip system is adapted to control at least one of the actuators in the end effector unit for bringing the distal end back essentially at the desired location. The controller and the anti-slip controller can be a common controller or they may be separate controllers.
According to yet another embodiment, the gangway further comprises a secondary position sensor. The secondary position sensor is preferably a camera. According to an embodiment, the anti-slip system is configured to receive at least one secondary position signal from the secondary position sensor. The anti-slip system is configured to bring the distal end back essentially at the desired location based upon at least one of the at least one secondary position signal.
According to an embodiment, the outer surface is at least partially composed of a resilient material. The resilient material may be a rubber or silicone or at least one of their compounds.
The end effector unit may also comprise an end effector unit controller. The end effector controller may be configured to coordinatively operate with a controller of the gangway. In some embodiments, at least one of the end effector unit controller and the gangway controller is configured to coordinatively operate with a dynamic positioning system of the vessel. In other words, the gangway, or the end effector unit, may also comprise an end effector unit controller. The end effector unit controller is operably or functionally connected to the rotatable element actuator for controlling the rotatable element actuator.
At least one of, the end effector controller, and the slew controller may be configured to coordinatively operate with the gangway controller. Furthermore, at least one of the end effector unit controller, the slew controller, and the gangway controller may be configured to coordinatively operate with the DP system.
The end effector unit may be operated in a driven mode, or it may be operated in a non-driven mode.
The present teachings also relate to a method for repositioning a gangway to a desired position on an installation or a target structure, the gangway comprising an end effector unit having an outer surface at least a certain portion of which is adapted to be in contact with the installation; the method comprising the steps of:
According to another aspect, the method, additionally or alternatively, comprises the steps of:
Present teachings also relate to a method for repositioning a gangway distal end substantially close to a desired position on an installation or a target structure, the gangway comprising an end effector unit having an outer surface at least a certain portion of which is adapted to be in contact with the installation; the method comprising the steps of:
The method may further comprise the steps of:
The movement in the gangway may be effected using a slew actuator driven by a slew controller. Additionally or alternatively, the movement in the gangway is effected using the end effector unit. In other words, the actuator may be a slew actuator driven by a slew controller and/or the actuator is an end effector unit actuator.
Present teachings can also provide a vessel or watercraft comprising a gangway as herein disclosed. The vessel can be any kind of ship, boat, hovercraft or such a watercraft suitable for transport on or in water.
Present teachings can also provide an installation, fixed or floating, in water or on land, comprising a gangway as herein disclosed.
Present teachings can also provide a computer software product for implementing any method steps disclosed herein. Accordingly, the present teachings also relate to a computer readable program code having specific capabilities for executing any method steps herein disclosed. In other words, the present teachings relate also to a non-transitory computer readable medium storing a program causing an electronic device to execute any method steps herein disclosed.
Various embodiments have been described above for a method for controlling a gangway, and for a gangway. Those skilled in the art will understand, however that changes and modifications may be made to those examples without departing from the spirit and scope of the following claims and their equivalents. It will further be appreciated that aspects from the method and product embodiments discussed herein may be freely combined.
Certain embodiments of the present teachings are further summarized in the following clauses.
Clause 1.
Clause 2.
Clause 3.
Clause 4.
Clause 5.
Clause 6.
Clause 7.
Clause 8.
Clause 9.
Clause 10.
Clause 11.
Clause 12.
Clause 13.
Clause 14.
Clause 15.
Clause 16.
Clause 17.
Clause 18.
Clause 19.
Clause 20.
Clause 21.
Clause 22.
Clause 23.
Clause 24.
Clause 25.
Clause 26.
Clause 27.
Clause 28.
Clause 29.
Clause 30.
Clause 31.
Clause 32.
Clause 33.
Clause 34.
Clause 35.
Clause 36.
Clause 37.
Clause 38.
Clause 39.
Clause 40.
| Number | Date | Country | Kind |
|---|---|---|---|
| 20171521 | Sep 2017 | NO | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/EP2018/075457 | 9/20/2018 | WO | 00 |
| Publishing Document | Publishing Date | Country | Kind |
|---|---|---|---|
| WO2019/057813 | 3/28/2019 | WO | A |
| Number | Name | Date | Kind |
|---|---|---|---|
| 3468280 | Williams | Sep 1969 | A |
| 3879784 | Kummerman | Apr 1975 | A |
| 5226204 | Schoenberger | Jul 1993 | A |
| 6724314 | Hutton | Apr 2004 | B2 |
| 6898816 | Tholen | May 2005 | B2 |
| 7543542 | Jakobsson | Jun 2009 | B2 |
| 7690065 | Muller | Apr 2010 | B2 |
| 8302237 | Shimizu | Nov 2012 | B2 |
| 8925130 | Bedford | Jan 2015 | B2 |
| 8959694 | Clarke | Feb 2015 | B2 |
| 9121148 | Johnson | Sep 2015 | B2 |
| 9643690 | Hessels | May 2017 | B2 |
| 10392083 | Van Aalst | Aug 2019 | B2 |
| 20030145404 | Hutton | Aug 2003 | A1 |
| 20040237224 | Hutton | Dec 2004 | A1 |
| 20070028404 | Hutton | Feb 2007 | A1 |
| 20080099967 | Spratte | May 2008 | A1 |
| 20080109970 | Hutton | May 2008 | A1 |
| 20080229525 | Hutton | Sep 2008 | A1 |
| 20110119842 | Park | May 2011 | A1 |
| 20120030887 | Corboy | Feb 2012 | A1 |
| 20150158559 | Mueller | Jun 2015 | A1 |
| 20160144932 | Salen | May 2016 | A1 |
| 20160375813 | Colantonio | Dec 2016 | A1 |
| 20200172204 | Robertson | Jun 2020 | A1 |
| 20200239111 | Zijlmans | Jul 2020 | A1 |
| Number | Date | Country |
|---|---|---|
| 3503836 | Oct 1986 | DE |
| 2167714 | Jun 1986 | GB |
| WO-99053144 | Oct 1999 | WO |
| WO-2000015489 | Mar 2000 | WO |
| WO-2011154730 | Dec 2011 | WO |
| WO-2012069825 | May 2012 | WO |
| WO-2013174886 | Nov 2013 | WO |
| Entry |
|---|
| Knoflacher, Nikolaus; International Search Report; PCT/EP2018/075457; dated Dec. 4, 2018; 5 pages. |
| Number | Date | Country | |
|---|---|---|---|
| 20200262521 A1 | Aug 2020 | US |
