Load control apparatus and method for controlling movement of a suspended load

Abstract

A load control apparatus and method for controlling movement of a suspended load is disclosed. The load control apparatus includes: a base for attachment to or forming part of a load; a support element pivotally secured to and extending from the base for receiving and/or connecting to a lift line; and actuation means connected to the support element and to the base at respective positions which are spaced from the pivotal connection between the support element and the base such that actuation, in use, of the actuation means causes the base to pivot relative to the support element.

Claims

1. A load control apparatus for controlling movement of a suspended load, the apparatus comprising: a base for attachment to or forming part of a load; a support element pivotally secured to and extending from the base for connecting to a lift line; actuation means comprising two actuators connected to the support element and to the base at respective positions which are spaced from the pivotal connection between the support element and the base such that actuation, in use, of the actuation means causes the two actuators to apply a force to the support element and the base such that the base pivots relative to the support element; wherein the two actuators extend at an angle with respect to each other from the support element such that actuation of each of the two actuators causes the base to pivot about a different axis; and a control means operable to control the actuation of the actuation means in response to movement of the supsended load.

2. A load control apparatus as claimed in claim 1, wherein the support element comprises a column pivotally connected to a central portion of the base at or adjacent a first end thereof, the actuation means being connected to the column at or adjacent a second end thereof and connected to an outer portion of the base.

3. A load control apparatus as claimed in claim 2, wherein the column comprises a connection means at or adjacent the second end for connecting to the lift line.

4. A load control apparatus as claimed in claim 3, wherein each of the two actuators is connected to the column at or adjacent the second end and to different outer portions of the base such that actuation, in use, of each actuator causes the base to pivot about a different axis relative to the column.

5. A load control apparatus as claimed in claim 2, wherein the column is configured to receive, in use, a portion of a lift line that is connected to the base or to the load.

6. A load control apparatus as claimed in claim 1, wherein the pivotal connection allows the support element to pivot about two or more axes relative to the base.

7. A load control apparatus as claimed in claim 1, wherein the pivotal connection between the base and the support element comprises a universal joint or a gimbal unit.

8. A load control apparatus as claimed in claim 1, wherein the base comprises a plate with a central portion to which the support element is pivotally connected and an outer portion to which the actuation means is connected.

9. A load control apparatus as claimed in claim 1, wherein the actuation means is pivotally connected to each of the support element and the base.

10. A load control apparatus as claimed in claim 1, wherein the actuation means comprises a hydraulic or pneumatic or electromechanical actuator.

11. A load control apparatus as claimed in claim 1, wherein the support element comprises connection means including one or more lifting holes for receiving a lifting element attached to a lifting line.

12. A load control apparatus as claimed in claim 1, wherein the base comprises one or more attachment features for attaching the base to the load.

13. A method of controlling movement of a load using the apparatus as described in claim 1, the method comprising applying via the actuation means a pivoting force between the support element and the base to oppose a movement of the suspended load.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Embodiments will now be described by way of example only with reference to the accompanying drawings in which:

(2) FIG. 1 shows a load control apparatus according to one embodiment, when positioned on a crane;

(3) FIG. 2 is a close up perspective view of the load control apparatus of FIG. 1, when in a neutral position;

(4) FIG. 3 is a plan view of the load control apparatus of FIG. 2;

(5) FIGS. 4 and 5 are side elevation views of the load control apparatus of FIGS. 2 and 3;

(6) FIG. 6 is a perspective view of the load control apparatus of FIG. 1, when inclined in a single plane;

(7) FIG. 7 is a side elevation view of the load control apparatus of FIG. 6;

(8) FIG. 8 is a perspective view of the load control apparatus of FIG. 1, when inclined in two planes;

(9) FIG. 9 is a side elevation view of the load control apparatus of FIG. 8; and

(10) FIGS. 10 and 11 are schematics showing forces acting upon a lift line and a load.

DETAILED DESCRIPTION

(11) Referring now to the drawings, FIG. 1 shows a load control apparatus 100 in use with a crane assembly 102. Here the load control apparatus is shown in use with a tower crane (or balance crane) system. It will be appreciated that the load control apparatus may be also used with many other types of crane or lifting apparatus (e.g. telescopic cranes, truck mounted cranes, overhead cranes, A-frames).

(12) The lift control apparatus 100 attaches to a lift line 104 of the crane assembly 102 (e.g. via a hook at the end of the lift line). A lift load 106 attaches to the lift control apparatus 100 and is suspended therefrom.

(13) FIGS. 2 to 5 show one example of the lift control apparatus 100 in more detail.

(14) The lift control apparatus 100 includes a base 108 to which a load 106 can be connected. Aptly, the load 106 is connected to the base 108 with a bottom surface of the base 108 contacting a surface of the load 106. Upon connection, the bottom surface of the base 108 is aptly flush with a surface of the load 106, as shown in FIG. 1. In this way, any forces applied to the base 108 can be transmitted directly to the load.

(15) In this example, the base 108 includes a substantially circular plate with a circular central portion and a ring-shaped peripheral portion connected to the central portion by four radial spokes. The base 108 is formed from steel, though other suitable materials may include aluminium, chrome and/or nickel based alloys, titanium composite materials, or carbon-fibre based materials, or any other suitable materials, for example. Aptly the base is unstiffened, namely the base should be stiff enough to transmit forces induced by the actuators to the load without significant flexing of the base that could cause excessive wear on the apparatus.

(16) A support element 110, e.g. a column or beam, is pivotally secured to and extends from the base 108. In this example, the support element 110 is in the form of a substantially cylindrical column and is formed from steel, though other materials may also be used. For example, the support element may be formed from aluminium, chrome and/or nickel based alloys, titanium composite materials, or carbon-fibre based materials, or any other suitable materials. The support element is shown at a substantially perpendicular angle to the base.

(17) A first, lower end of the support element 110 is pivotally secured to the centre of the base 108. A second, upper end of the support element 110 includes a connection means in the form of a pair of upstanding brackets 116 with through holes (or lifting holes) into which a lift line 104 or lift hook can be inserted and connected. The lift control apparatus 100 is thus configured such that the weight of the load 106 is transmitted to the lift line 104 via the base 108 and support element 110.

(18) In this embodiment, the support element 110 is connected to the base 108 by a connection that allows inclination of the support element 110 with respect to the base 108 in all planes passing through a central axis Z orthogonal to the base 108. That is, the support element 110 can pivot about its first end with respect to the base 108 in all directions, but no rotation of the support element with respect to the base is possible. In this way, the pivotal connection allows the support element 110 to pivot about two or more axes relative to the base 108.

(19) In this example, the pivotal connection is in the form of a gimbal unit 114 with two axes of rotation to allow inclination of the support element 110 with respect to the base 108 in all planes passing through a central axis Z orthogonal to the base 108. Of course, other universal joints or couplings or a series of couplings may provide the pivotal connection.

(20) Each of a pair of actuators 112 is connected to the support element 110 and to the base 108 at respective locations, which are spaced from the gimbal unit 114. In this example, the actuators 112 are hydraulic rams each including a cylinder and a piston rod. Aptly the hydraulic rams 112 are positioned with the cylinder at the end closest to the base 108. This has the advantage that the weight can be better distributed over the apparatus with the centre of gravity closer to the base.

(21) Each actuator 112 connects the upper end of the support element 110 to a different (outer) position of the base 108. In this way, in use, actuation of each actuator causes the base 108 to pivot in a different direction and/or about a different axis relative to the column. In this example two actuators 112 extend from the upper end of the support element 110 to the base 108 in radial directions that are orthogonal with respect to each other, as can be seen most clearly in FIG. 3.

(22) The actuators 112 are pivotally connected to each of the base 108 and support element 110 via pivoting joints 118 to allow inclination of the actuator 112 with respect to the base 108 and the support element 110. Each pivoting joint 118 includes a pair of spaced brackets with opposed holes that each receive a pin 120 which engages a hole, bushing or bearing of the actuator 112. It will be appreciated that the hole, bushing or bearing of the actuator 112 should be configured to allow at least some inclination of the base with respect to the support element in all directions (see, for example, FIG. 9). Alternatively, the actuator 112 can be connected at one or both ends via a universal joint, which would allow the support element 110 to pivot more freely in all directions with respect to the base 108.

(23) A control unit or control means can be mounted onto the apparatus for controlling the actuators in response to movement of the load. The control unit can include one or more sensors for sensing movement of the load. A power supply unit can be mounted onto the apparatus and supplies power to the control unit and/or pressurised hydraulic fluid to the actuators 112. Alternatively, the control unit and/or the power supply may be mounted on the lifting device or on the ground or deck of a vessel on which the lifting apparatus is located, for example. In some embodiments, the actuators 112 may be electromechanically driven, for example such that a single electrical power supply may be used to power both the control unit and the actuators. In some embodiments the load may be a powered load capable of supplying power to the control unit and actuators. As such, when using a powered load an additional power supply unit may not be required.

(24) In use, a lift load 106 can be attached to the base 108 via one or more attachment features. The attachment features may include one or more fasteners, such as bolts, and/or any one or more of hooks, frames, shackles and/or lines.

(25) FIGS. 6 and 7 illustrate the lift control apparatus 100 with one actuator 112b extended from a neutral position. In this example actuator 112b is in an extended position and is longer than actuator 112a, which is in a neutral position. The base 108 is therefore inclined in a single plane with respect to the support element 110. It will be appreciated that a similar inclination of the base 108 in the opposite direction can be achieved by contracting the actuator 112b compared to its neutral position.

(26) FIGS. 8 and 9 illustrate the lift control apparatus 100 with both actuators 112 extended from a neutral position. In this example both actuators 112a, 112b are extended compared to the neutral position. The base 108 is therefore inclined in two planes with respect to the support element 110. Again, it will be appreciated that a similar inclination of the base 108 in the opposite direction can be achieved by contracting both of the actuators 112a, 112b compared to their neutral position.

(27) In use, actuation of the actuator 112 causes the base 108 to pivot relative to the support element 110 (and lift line 104). In other words, the actuators 112 can extend and retract to apply a force to the support element 110 and the base 108. As an actuator is extended or retracted, the lift line 104 is deflected by the applied force at the connecting portion 116 to the support element 110, thereby acting against any motion of the lift load 106. In other words, the applied force acts to oppose the inertia of the lift load 106, and thereby reduce any oscillatory motion of the load 106.

(28) Aptly the force applied by the actuators 112 is nominally less than the lift load and does not form part of the primary load path. This reduces the chances of the load 106 being directed in the opposite direction to the original motion by the actuators 112 and prevents the load control apparatus from causing further unwanted swinging motion.

(29) For example, during lifting of the load 106, the load 106 may start to swing in a pendulum like motion. The controller can monitor the movement of the load 106, and in response to movement of the load 106, can operate the actuators 112. One or more of the actuators 112 can be extended or retracted to apply a pivoting force to the support element 110 and the base 108. This force opposes the inertia of the load 106 and therefore acts to decelerate and reduce the movement of the load.

(30) This operation is shown more clearly in FIGS. 10 and 11, which illustrate a simplified two dimensional version of the forces applied by the actuators 112.

(31) FIG. 10 illustrates the forces applied by the actuators 112 when the load 106 is swinging in a clockwise direction on the page (velocity V.sub.CW). As the load 106 swings in a clockwise direction the actuator 112 is extended from its neutral position. The actuator 112 therefore applies a force F.sub.1 to the lift line 104, thereby deflecting the lift line to the left as shown in the Figure. I.e., the actuator deflects the lift line in the direction of movement of the load 106). An opposite force F.sub.2 is consequently applied to the load to oppose the clockwise swing V.sub.CW, thereby decelerating the load 106 as shown by A.sub.ACW.

(32) FIG. 11 illustrates the forces applied by the actuators 112 when the load 106 is swinging in an anticlockwise clockwise direction on the page (velocity V.sub.ACW). As the load 106 swings in an anti-clockwise direction the actuator 112 is contracted from its neutral position. The actuator therefore applies a force F.sub.3 to the lift line 104, thereby deflecting the lift line to the right as shown in the Figure. So, the actuator deflects the lift line in the direction of movement of the load 106). An opposite force F.sub.4 is consequently applied to the load to oppose the anti-clockwise swing V.sub.ACW, thereby decelerating the load 106 as shown by A.sub.CW.

(33) The actuators 112 can be continually controlled by the control unit to extend and contract to oppose movement of the load 106 as illustrated in FIGS. 10 and 11. Of course, when two or more actuators 112 are used, the swing movements of the load 106 can be controlled in all directions by extending and/or contracting the relevant actuator(s) 112 as required.

(34) When landing a load 106 on a platform that is not moving relative to the lifting apparatus (e.g. moving a load from one position on land to another position on land), the load control apparatus 100 can be set to reduce any movement of the load 106 with respect to the lifting apparatus such that there is very little or no relative movement of the load with respect to the lifting apparatus as the load is placed in its landing position.

(35) However, when landing on a platform that is moving relative to the lifting apparatus (e.g. moving a load from land to a deck on a vessel when the crane 102 is positioned on land), the relative movement of the landing platform or deck with respect to the load also should be considered. For example, a sensing means operatively connected to the control means on the lifting apparatus may be positioned on the landing platform to sense motion of the landing platform. The further sensing means may then transmit motion data to the control means on the lifting apparatus. The control means on the lifting apparatus can then use the relative values of displacement, velocity and acceleration to determine how to control the actuators to affect movement of the load appropriately with respect to the movement of the landing platform.

(36) The load control apparatus 100 can be used with any existing crane 102 or lifting apparatus 102 since it can be attached directly to a crane hook or a lifting line 104. This has the additional advantage that the apparatus does not affect the load certification of the crane 102 because the crane 102 itself does not require any modification.

(37) The load control apparatus is also much lighter that known damping systems and typically can weight around 70 kg, though of course the actual weight of the apparatus will depend on the lift load requirements. This means that using the load control apparatus will not significantly affect the load mass that a lifting device can hold.

(38) In some embodiments, the lift control apparatus 100 may further include at least one compass or compass heading mounted on the lift control apparatus itself and/or on a landing platform to determine the relative orientations of the load with respect to the landing platform and allow for lift load rotation about the lift line axis.

(39) In an alternative arrangement to the embodiment described above, the support element may include a tubular column or other hollow column structure. The lift line of the lifting apparatus can then extend through the tubular column and attach directly to the lift load. As such, when the lift line is connected to the load (e.g. via a hook), the tubular column can brace against the portion of the lift line that is received in the tubular column. The portion of lift line received in the tubular column is therefore effectively part of a rigid column structure and the apparatus can function in a similar manner to the above-described embodiment.

(40) In an alternative arrangement to the embodiment described above, the base may form part of the load. That is, a base may be integrated into the load itself. This could be a similar base to the one described above having a plate, or the base could simply include portions of the load to which the support element and the actuators are or can be connected.

(41) Although the embodiment above has been described having two actuators 112, it will be appreciated that one, three, four or more actuators 112 may be used. Aptly, the load control apparatus 100 includes at least two actuators to allow inclination of the support element 110 in all planes with respect to the base 108. Of course, three or four actuators may also be used and can work together to affect movement of the load.

(42) For example, four actuators 112 may be equally spaced about the support element 110 and outer portion of the base 108. In this example as one actuator 112 extends, the actuator opposite would contract. This arrangement may be advantageous for particularly heavy loads as two actuators can act together to apply a force to the lift line and affect movement of the load.

(43) Although the actuators have been described above as extending orthogonally with respect to each other from the support element, it will be appreciated that other angles may also be possible. For example, the actuators may extend only approximately orthogonally with respect to each other from the support element, or may extend at any other suitable angle with respect to each other from the support element.

(44) It will be appreciated that the actuators 112 do not need to extend between the base 108 and the second end of the support element 110. Alternatively, the actuator 112 may extend between the base 106 and a position between the ends of the support element 110, which may be adjacent the second end. Alternatively, the actuator 112 may be connected to the support element 110 by a bracket that extends beyond the second end thereof. In this way, the actuators 112 can still operate to exert a force on the support element 110 and deflect the lift line to reduce the movement of the load 106.

(45) Although the actuators have been described above as hydraulic rams, other actuators, for example pneumatic or electromechanical actuators, may also be used. Although the support element described above is a substantially cylindrical column, other suitable support elements may be in the form of a rod, post, pole, beam, or bar having any suitable shape, for example.

(46) With the present invention, the centre of gravity of the load is changed against the oscillating movement of a swinging load. Thus, negative work (negative angular momentum) is added to the system. As the load swings, the actuator changes the centre of mass against the direction of swing, reducing the angular momentum.

(47) With the present invention, a load control apparatus is provided that can actively respond to movement of a load and mitigate against the effects of a swinging motion. Also, the apparatus can respond to movement of a suspended load and apply a force to oppose the movement of the load.

(48) Also, the load control apparatus may allow lifting apparatus in worse sea conditions compared to the conditions permissible for previously known lifting apparatus.

(49) Throughout the description and claims of this specification, the words comprise and contain and variations of them mean including but not limited to, and they are not intended to (and do not) exclude other moieties, additives, components, integers or steps. Throughout the description and claims of this specification, the singular encompasses the plural unless the context otherwise requires. In particular, where the indefinite article is used, the specification is to be understood as contemplating plurality as well as singularity, unless the context requires otherwise.

(50) Features, integers, characteristics, compounds, chemical moieties or groups described in conjunction with a particular aspect, embodiment or example of the invention are to be understood to be applicable to any other aspect, embodiment or example described herein unless incompatible therewith. All of the features disclosed in this specification (including any accompanying claims, abstract and drawings), and/or all of the steps of any method or process so disclosed, may be combined in any combination, except combinations where at least some of such features and/or steps are mutually exclusive. The invention is not restricted to the details of any foregoing embodiments. The invention extends to any novel one, or any novel combination, of the features disclosed in this specification (including any accompanying claims, abstract and drawings), or to any novel one, or any novel combination, of the steps of any method or process so disclosed.

(51) The reader's attention is directed to all papers and documents which are filed concurrently with or previous to this specification in connection with this application and which are open to public inspection with this specification, and the contents of all such papers and documents are incorporated herein by reference.

(52) It will be appreciated by those skilled in the art that several variations to the aforementioned embodiments are envisaged without departing from the scope of the invention. It will also be appreciated by those skilled in the art that any number of combinations of the aforementioned features and/or those shown in the appended drawings provide clear advantages over the prior art and are therefore within the scope of the invention described herein.