Crane system

Abstract

The present invention relates to a crane system (2) comprising a trolley (7) to support a load (18) and movable about a horizontal direction to provide movement of the load (18) in a horizontal direction accordingly and a carrying member (10) supported by the trolley (7) and configured to carrying the load (18) in use. A sensor (32) measures the tension of the carrying member (10) and a tensioning means (8) varies the tension of the carrying member (10). A controller (20) is configured to move the trolley (7) toward a position where the trolley (7) is vertically above the load (18) during a centering routine; and the tensioning means (8) is configured to maintain the tension within a predetermined parameter during movement of the trolley (7).

Description

[0001] Crane system

[0002] The present disclosure relates to a crane system, in particular but not limited to, a control system and method for a crane system.

[0003] Background of the Invention

[0004] Crane systems may be used to lift and then move a load. An overhead crane system comprises a hoist comprising a trolley movable along a bridge or beam to provide movement of the load. The hoist comprises hoisting mechanism to provide vertical movement of the load. If during lifting of the load, the load is not directly below the hoist, then as the load disengages from the ground, the load may start to swing such to a position directly below the hoist. This swinging motion may damage the load, the crane and / or provide a dangerous environment.

[0005] A prior art solution is provided in WO 2013 / 041770. The system uses an angle sensor to determine if the rope carrying the load is at an angle. In use, the user manually tightens the ropes to ensure measurement of the angle is accurate (i.e. the rope does not sag). The system may activate once the system detects that the rope is under sufficient tension. The system provides an indication to the user whether the trolley is outside the desired position. If so, the user manually adjusts the trolley’s position and re-tensions the rope. This process is repeated until the trolley is in a suitable position. In other embodiments, the system automatically moves the trolley until the load is directly beneath the trolley.

[0006] The inventor has found numerous problems with the prior art. As the tension of the rope is manually adjusted, it is easy for the user to over-tension and accidentally lift the load or under-tension and not have accurate determination of the angle. In the automatic example, the system simple moves to reduce the measured angle. This may cause rope to sag or the load to lift, as the tension in the rope is not controlled by the system. Either of these situations could lead to errors in the operation of the system and / or create dangerous load swings.

[0007] It is an aim of the present invention to overcome or ameliorate one or more of the above problems.

[0008] Statement of Invention

[0009] According to a first aspect of the invention, there is provided: crane system comprising: a trolley or hoist to support a load and movable about a horizontal direction to provide movement of the load in a horizontal direction accordingly; a carrying member supported by the trolley / hoist and configured to carrying the load in use; a sensor to measure the tension of the carrying member and a tensioning means to vary the tension of the carrying member; a controller configured to move the trolley / hoist toward a position where the trolley / hoist is vertically above the load during a centering routine; and where the tensioning means is configured to maintain the tension within a predetermined parameter during movement of the trolley / hoist.

[0010] The controller may be configured to maintain the tension within the predetermined parameter until the trolley is vertically above the load in use. This may provide a centering routine. The tension may be maintained throughout the centering routine. The tension may be continuously maintained throughout the centering routine (i.e. tension is maintained with movement of the trolley).

[0011] The predetermined parameter may comprise a set-point (e.g. threshold) and / or range. The controller may be configured to maintain the tension in the carrying member at said set-point and / or within said range. The predetermined parameter may be sufficient to maintain tautness in the carrying member. The predetermined parameter may be less than the force required to lift the load. The predetermined parameter may be a function of the weight of the load to be carried in use. The controller may be configured to receive an input of the weight of the load. The function may comprise the weight in addition to a constant bias factor. The predetermined parameter may be a function of the measured weight at the beginning of the centering routine.

[0012] The tensioning means may comprise a hoist system configured to vertically move the load in use. The controller may control movement of the hoist system to maintain said tension. The hoist system may comprise a spindle or drum. The controller may control the spindle or drum.

[0013] The hoist system may comprise an inverter to drive a motor of the hoist system. The controller may be configured to generate a frequency signal to drive the motor. The controller may vary the frequency to maintain the tension accordingly.

[0014] When the trolley is moved toward where the trolley is vertically above the load (i.e. when the centering routine is active), the controller may be configured to disregard a user input to control the trolley. The controller may be configured to disregard a user input to control horizontal and / or vertical movement of the load.

[0015] The tension sensor may be configured to measure the torque or load of the hoist system configured to vertically move the load in use. The tension sensor may measure the torque or load of a motor of the hoist system. The torque or load may be determined by an inverter configured to drive the motor. The controller may be configured to generate a target torque signal to the inverter to drive the motor. The controller may vary the torque to maintain the tension accordingly.

[0016] The tension sensor comprises an overload sensor provided on the crane system. The controller may be configured to communicate with said sensor. The tension sensor may comprise a retrofit sensor. The sensor may be configured to measure a relatively low load (i.e. relative to a maximum load).

[0017] The controller may comprise a proportional controller. The controller may be configured to control the tensioning means in proportion to a difference in a measured tension and the predetermined parameter.

[0018] A crane system may comprise a filter configured to filter one or more signal. The filter may be configured to filter a signal from the tension sensor. The filter may comprise a low-pass filter.

[0019] The crane system may comprise a sensor configured to measure the angle of the carrying member relative to the trolley. The controller may be configured to use said angle to move the trolley toward a position where the trolley is vertically above the load. The angle sensor comprises one or more of: an optical, time-of-flight or radio-based system; an inclinometer; or a rotary encoder.

[0020] The controller may be integrated into or be part of the inverter.

[0021] According to a further aspect, there is provided: a method controlling a crane system comprising: providing a trolley or hoist to support a load and movable about a horizontal direction to provide movement of the load in a horizontal direction accordingly; providing a carrying member supported by the trolley / hoist and configured to carrying the load in use; measuring the tension of the carrying member; measuring the angle of the carrying member relative to the trolley / hoist; moving the trolley toward a position where the trolley / hoist is vertically above the load in use; and maintaining the tension within a predetermined parameter during movement of the trolley / hoist.

[0022] The carrying member may comprise a motor to vary the length thereof. The hoist / trolley may comprise a motor to effect movement of the horizontal position thereof. The bridge or gantry may comprise a motor to effect movement of the horizontal position thereof.

[0023] The crane may comprise an overhead and / or jib crane.

[0024] According to a further aspect, there is provided: a computer program or computer readable medium comprising program instructions which, when executed by the computer, cause the computer to carry out a computer process implementing the method according to claim 14.

[0025] Any aspect of the invention may be combined with any other aspect of the invention where practicable.

[0026] Description

[0027] Embodiments of the present invention are described below, by way of example only, with reference to the accompanying drawings:

[0028] Figure 1A shows a schematic view of a first crane system;

[0029] Figure 1B shows a schematic view of a second crane system; Figure 2 shows a schematic view of a control system; Figure 3 shows a schematic view of a control regime.

[0030] A crane system 2 is shown schematically in figure 1 . The crane comprises a bridge or overhead crane. The crane 2 comprises bridge portion 4. A hoist mechanism 6 is mounted to the bridge portion 4 and is movable along the length thereof. The bridge 4 may comprise a girder, beam, rail, jib or the like. The hoist 6 comprises a carriage or trolley 7 movably mounted to the bridge 4. The carriage may comprise a wheel, bearing or roller to provide movement thereof. Movement may be effected by a motor 8 provided on the trolley 7. The motor may comprise a gearbox or the like. The gearbox may then be operatively connected to the wheel / bearing / roller. In other embodiments, the trolley 7 may be effected via external driving means (e.g. via a screw drive or endless loop).

[0031] A motor may be provided to effect movement of the gantry / bridge portion, where the gantry / bridge 4 is movable. The motor may comprise a gearbox. The gearbox may be connected to wheel or the like to drive the gantry / bridge. The gantry / bridge 4 may be mounted to gantry, rail, guide or support structure to allow horizontal movement thereof. The gantry / bridge 4 may be movable along a rail 9 or pair or rails. The bridge may comprise one or more wheel 11 configured to engage the ground, rail or the support structure where provided. The bridge may comprise a plurality of legs 13. The wheels 11 are provided on the legs 13. This provides a gantry crane like arrangement.

[0032] In the embodiment shown in figure 1A, the rail 9 may be provided on fixed structure. The wheels 11 are therefore mounted directly to the bridge 4. This provides an overhead crane like arrangement.

[0033] A carrying member 10 is provided on the hoist 6 to allow connection to a load in use. The carrying member 10 is typically flexible. For example, the carrying member may comprise a rope, cable or chain. The rope may comprise a metallic (e.g. steel) or polymeric / synthetic rope. In some embodiments, the carrying member may be rigid or comprise rigid portions. A connector 12 is provided at an end of the carrying member 10 for connection to a load. The connector 12 may comprise a hook, eyelet, carabiner or the like. The carrying member 10 is presented in a schematic manner in figure 1 , and it can be appreciated that the carrying member 10 may be looped over a pulley (e.g. to form a pulley system) and / or comprises a plurality of parallel members. The “end” of the carrying member 10 may comprise a lowermost point of the carrying member 10 in use.

[0034] The crane 2 may be configured to raise / lower the load. For example, the hoist 6 may comprise a winch, pulley system and / or other hoisting mechanism for effecting movement of the load in a vertical direction in use. The winch / pulley may pay-out or pay-in the carrying member 10. A drum (e.g. a rope drum) or spindle may be provided to store the carrying member 10. A motor may be provided to effect movement in the vertical direction (i.e. to rotate the drum). The motor may comprise a gearbox.

[0035] A remote controller 14 may be provided to provide operation of the crane 2. The remote controller 14 may allow adjustment of the position of the trolley 7 along the bridge 4 and / or the vertical position of the load. The remote controller 14 may be wired or wireless. The remote controller 14 may comprise a pendant or radio controller.

[0036] It can be appreciated that the exact form of the crane is not pertinent to the invention at hand, and in generally terms, the system comprises a hoist movable in a horizontal direction. The crane may comprise any suitable type of crane, for example one or more of: an overhead / bridge crane; a tower crane; a gantry crane (e.g. the bridge portions is movable); deck crane; jib crane; or hammerhead crane. Typically, any of the aforementioned driving motors are electric motors.

[0037] During a centering routine, the crane system 2 is configured automatically apply a tension to the carrying member 10. The applied tension is optimised to ensure that the carrying member 10 is sufficiently taut, without lifting the load 18. The tension is applied as the trolley 7 moves toward a position vertically above the load 18.

[0038] The tensioning system is shown in detail in figures 2 and 3. The system comprises a controller 20. The controller 20 comprises any suitable processing system. The controller 20 may comprise one or more of: a processor; microprocessor; microcontroller; volatile and / or non-volatile memory; SoC etc. The controller 20 may comprise an analog and / or digital computing device. The controller 20 may comprises an embedded or industrial PLC. A centering module 22 configured to control the centering action of the trolley 7. A hoist control module 24 controls action of the trolley 7 (i.e. the horizontal position thereof and / or the vertical control of the carrying member 10). A tension control module 26 is configured to control the tension of the carrying member 10. Although modules are shown as being provided by a single controller in figure 2, it can be appreciated that each of the module may be provided by respective controllers, and each controller may comprise hardware / software as previously described.

[0039] The remote control 14 is operatively connected to the controller 20 to allow commands to be provided to trolley 7 and / or hoist mechanism. For example, the operator may provide movement commands in the horizontal and / or vertical direction. This may allow the trolley 7 to operate in a conventional fashion.

[0040] An angle sensor 28 is used to determine the angle of the carrying member 10 / connector 12. The angle may be determined relative to a datum, for example, an axis of the trolley 7, or relative to the vertical axis. The angle may be defined as the angle, 6, defined between the vertical axis 16 and the carrying member 10 (see figure 1 ). The angle sensor 28 is operatively connected to the controller, in particular, the centering module 22.

[0041] A variety of sensing methods may be used to determine the angle or inclination of the carrying member, for example, one or more of:

[0042] • An inclinometer attached to a portion of carrying member 10 and / or the connector 12. The inclinometer may be attached near a terminal end of the carrying member 10 (the end adjacent the trolley 7 and / or the connector 12). Multiple inclinometers may be provided. The inclinometers may be spaced along the axis of the carrying member 10. The angle may be determined as an average of the inclinometers. The sensor(s) may be provided at or adjacent a fixed end of the carrying member 10 (i.e. the end not configured to be reeled in). This ensures the sensor is not fed into a drum etc.

[0043] • A potentiometer or encoder on fixed end joints or pivots connecting the carrying member 10 to the trolley 7.

[0044] • Using an optical sensor. For example, one or more camera may be provided to determine the position of the carrying member 10 and / or connector 12. Two or more cameras may be used to capture a stereo image of the carrying member / connector, thereby allowing determination of the position thereof. The system may use machine learning or Al to allow accurate detection.

[0045] • Using time-of-flight (ToF) type systems. For example, RADAR, LIDAR, laser range finding systems may be used. This allows passive detection of the position of the carrying member / connector.

[0046] • Using active tracking systems. The carrying member / connector is configured to emit a signal allowing determination of the position thereof. For example, the system may use one or more of: ultrasound; a radio beacon; or an ultra wide band (UWB) radio.

[0047] It can be appreciated that where optical, ToF, or active tracking systems are used to determine the position of the carrying member / connector, a virtual angle may be determined (i.e. rather than calculating the physical angle, a virtual angle is calculated given a known length and position of the carrying member 10 / connector 12). In some embodiments, the angle need not be determined at all, as the position or displacement, can be determined in absolute terms. Similarly, such systems can be used to determine the effective rope length or other variable.

[0048] An inverter command module 30 is configured to receive command from the controller 20 to control operation of the inverter / motor 8 accordingly. For example, the inverter command module 30 may receive a speed input. The inverter command module may then convert the speed input into a corresponding output frequency to drive the inverter and the motor 8.

[0049] Therefore, the determined input speed must be converted to corresponding output frequency. The output frequency, f, be defined by: where fnomis nominal frequency and snomis nominal speed. Frequency (and the associated travel speed) is limited by nominal frequency, so fand v maximum values are limited by fnom and Snom, respectively.

[0050] A load sensor 32 is configured to measure the tension or load experienced by the carrying member 10. The load sensor 32 may comprises one or more of:

[0051] • An existing load sensor on the crane. Such sensors are typically installed on cranes to measure load and / or to prevent overload situations. The sensor may be reconfigured to communicate with the controller 20, or the controller 20 may be configured to input the data using an existing connection (i.e. the controller is merely reprogrammed). It can be appreciated that the exact form of the sensor or connection is not pertinent to the invention at hand.

[0052] • A separate load sensor. The sensor may be retrofit to the crane 2. The sensor may comprise an operating range provided in low load situation (i.e. the sensor is configured to detect loads caused by tightening of the carrying member 10, but not when the load is fully supported). The tension measurement is therefore more accurate, as the sensitivity of the sensor is selected at the appropriate load. The load sensor may be provided on any of: the trolley 7; bridge 4; carrying member 10; or connector 12. The load sensor may comprise a pressure sensor or strain gauge.

[0053] • A sensor configured to measure hoisting motor load. The sensor measures the load or torque experienced by the motor. For example, this may be determined by measuring the electrical power required to maintain the hoist in position. The sensor may be provided by the inverter or inverter command module 30 (e.g. the torque is derived as a function of the motor input command and / or the output frequency). Alternatively, a mechanical sensor may measure the torque experienced by the motor (e.g. an axle thereof).

[0054] The tension of tautness of the of the carrying member 10 is controlled by a control regime 34, shown schematically in figure 3. The control regime 34 uses a proportional controller 36 (P-controller). The system therefore controls the tension in a proportional manner (i.e. the rate of adjustment of the tension is proportional to a difference in the measured tension relative to a set point).

[0055] The P-controller regime, P, may be defined by v = Pe where v is hoisting speed and e is setpoint error.

[0056] The error, e, may be defined by e = r - y, where r is a tension setpoint (i.e. a predetermined threshold tension) and y is the measured tension.

[0057] A controller gain P may be defined as: f5^ / ^nom where c is a tuning parameter and snomis nominal hoisting speed. The tuning parameter, c, may be tuned to get desired control behaviour. The tuning parameter may vary between different cranes, hoisting machinery and / or load / torque sensor. The tuning parameter may therefore be tuned or calibrated for a given crane system according to desired operation.

[0058] The tension setpoint, r, may be defined by one or more of: • A constant parameterized value. The value may be defined as: r = rconstant- The setpoint may therefore comprise a predetermined value or threshold. The value may be estimated and / or determined by experiment. The value may be provided as function of one or more parameter of the carrying member. For example, the setpoint may be determined by: the weight: the length: the density; the flexibility; or other physical characteristic of the carrying member 10.

[0059] • An offset that is added to measured rope tightness at the beginning of Hook Centering operation. When Hook Centering activates, a load value, I, is recorded. The setpoint is determined to r = I + rbias. The tension setpoint is therefore a function of the load weight. The weight of the load may be input by the user, measured, or estimated using other means. This may be beneficial where the measured load drifts over time.

[0060] It can be appreciated that the tension setpoint, r, may be defined by any suitable parameter. For example, the tension setpoint, r, may be defined by a range. This allows some tolerance of the acceptable range of the tension. The tension parameter may be set or input by the user. The parameter may be manually adjustable by the user. For example, the user could observe the tautness of the rope and adjust the parameter accordingly.

[0061] In some embodiments, the rope tension measurement, y, determined by the load may be filtered. The filtering may be provided by a filter 38. The filter may comprise one or more of: a high pass filter; low pass filter; and / or band pass filter. For example, a low-pass filter may be used to reduce noise. A band pass filter may be used to filter erroneous and / or non-realistic tensions. This may prevent the controller 36 acting unstably or unnecessarily. Filtering may be performed on the feedback signal y. Additionally or alternatively, filtering may be performed on the error signal, e. The filter 38 may be provided by the controller 20 and / or may be integrated in load sensor 32. The filter 38 may be analog or digital. It can be appreciated that the control system 34 may provided as part of the tension control module 26 and / or as part of the controller 20 overall, and the exact hardware arrangement is not pertinent to the invention at hand. Other controller types can also be applied, such as PD; PID; or state-feedback etc. Several controller tuning methods to set controller parameter(s) can be applied, such as linear, robust, and / or optimal control design.

[0062] Operation of the system

[0063] A load 18 is attached the connector 12. As shown in figure 1 , the load is horizontally offset from the vertical axis 18. The load 18 is therefore at angle 0 with respect to the vertical axis 16. The user activates the centering routine. This may be provided on the remote control 14. Once activated, the system is configured to switch from a normal hoisting mode (i.e. where the user is free to move the load 18 in the vertical / horizontal axis) to the automated centering system. A switch 40 (see figure 2) may be provided to switch from control via the hoisting control module 24 to the tension control module 26. The switch may comprise a physical or virtual switch. Where required, a weight of the load may be entered into the system.

[0064] Once the centering system is activated, the tension control module 26 is configured to measure the load, y, measured by the load sensor 32. The measured load, y, is compared to setpoint, r, and the P-controller 36 drives the hoist motor 8 accordingly. Typically, upon initialisation of the system there is some slack in the carrying member 10, and so the P-controller 36 drives the hoist motor 8 in an upwards direction. As the motor 8 is driven, the measured load, y, is continually monitored and the hoist motor 8 is driven until the measured load, y, reaches the setpoint tension, r, is reached. At this stage, the carrying member 10 is sufficiently taut that that angle, 0, can be determined accurately. The centering system may operate as described in WO 2013 / 041770, incorporated herein by reference.

[0065] The centering routine is engaged and the trolley 7 moves such that the load 18 is directly beneath the trolley 7 (i.e. such that 0 « 0). The trolley 7 may be moved by movement of the trolley 7 along the bridge and / or by movement of the bridge itself (i.e. about a 2-dimensional plane). During the centering routine, the tension of carrying member 10 may change (i.e. as the effective distance between the load 18 and the trolley 7 decreases). The tension control unit 26 continues to operate during the centering routine, such that the carrying member 10 remains sufficiently taut (i.e. at setpoint tension). This ensures that 0 is accurately determined throughout the centering routine.

[0066] During the centering routine, the user’s commands may be disregarded by the controller. In particular, any command to raise / lower the load via the hoist 6 may be disregarded to prevent interference with the tension monitoring system. This allows the system to operate in an optimal fashion and automatically. Once, the load is below the trolley 7, the system may automatically disengage the centering routine, and / or the user may manually disengage the system. Once the centering routine is disengaged, the user can use the system as normal.

[0067] The present system ensures that the carrying member remains taut at both initialisation and during operation of a centering routine. This allows more accurate determination of an angle of the carrying member relative to the vertical during the centering routine, thus increasing accuracy and stability of the centering system. Additionally, unwanted swaying or the load may be prevented and safety of lifting may be increased accordingly. The proportional controller helps ensure that the feedback loop remains stable and helps to eliminate undesirable jerking etc.

Claims

Claims:1 . A crane system (2) comprising: a trolley (7) to support a load (18) and movable about a horizontal direction to provide movement of the load (18) in a horizontal direction accordingly; a carrying member (10) supported by the trolley (7) and configured to carrying the load (18) in use; a sensor (32) to measure the tension of the carrying member (10) and a tensioning means (8) to vary the tension of the carrying member (10); a controller (20) configured to move the trolley (7) toward a position where the trolley (7) is vertically above the load (18) during a centering routine; and where the tensioning means (8) is configured to maintain the tension within a predetermined parameter during movement of the trolley (7).

2. A crane system according to claim 1 , where the controller (20) is configured to maintain the tension within the predetermined parameter during the centering routine.

3. A crane system according to any preceding claim, where the predetermined parameter comprises a set-point and / or range, and the controller (20) is configured to maintain the tension in the carrying member (10) at said set-point and / or within said range.

4. A crane system according to any preceding claim, where the predetermined parameter is a function of the weight of the load (18) to be carried in use.

5. A crane system according to any preceding claim, where the tensioning means (8) comprises a hoist system (6) configured to vertically move the load (18) in use, and the controller (20) controls movement of the hoist system (6) to maintain said tension.

6. A crane system according to any preceding claim, where the hoist system comprises an inverter to drive a motor (8) of the hoist system, and thecontroller (20) is configured to generate a frequency signal to drive the motor (8), and the controller (20) varies the frequency to maintain the tension accordingly.

7. A crane system according to any preceding claim, where during the centering routine, the controller (20) is configured to disregard a user input to control the hoist system (6) and / or trolley (7) movement.

8. A crane system according to any preceding claim, where tension sensor (32) is configured to measure the torque or load of a motor (8) of a hoist system configured to vertically move the load in use.

9. A crane system according to any preceding claim, where the controller (20) is configured to output a target torque signal to an inverter to drive a motor (8) of a hoist system (6), to maintain the tension accordingly10. A crane system according to any preceding claim, where the controller (20) comprises a proportional controller, and the controller (20) is configured to control the tensioning means (8) in proportion to a difference in a measured tension and the predetermined parameter.

11. A crane system according to any preceding claim, comprising a filter (38) configured to filter signal from the tension sensor (32).

12. A crane system according to any preceding claim, comprising a sensor (28) configured to measure the angle of the carrying member (10) relative to the trolley (7), and the controller (20) is configured to use said angle to move the trolley (7) toward a position where the trolley (7) is vertically above the load (18).

13. A crane system according to claim 12, where the angle sensor (28) comprises one or more of: an optical, time-of-fl ight or radio-based system; an inclinometer; or a rotary encoder.

14. A method controlling a crane system comprising:providing a trolley (7) to support a load (18) and movable about a horizontal direction to provide movement of the load (18) in a horizontal direction accordingly; providing a carrying member (10) supported by the trolley (7) and configured to carrying the load (18) in use; measuring the tension of the carrying member (10); measuring the angle of the carrying member relative (10) to the trolley (7); moving the trolley (7) toward a position where the trolley (7) is vertically above the load (18) in use; and maintaining the tension within a predetermined parameter during movement of the trolley (7).

15. A computer program or computer readable medium comprising program instructions which, when executed by the computer, cause the computer to carry out a computer process implementing the method according to claim 14.

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