Crane and method for crane control

Abstract

The present disclosure relates to a method for the control and/or the data acquisition of a crane, wherein at least one measuring device at the crane supplies one or more measured values for determining the position of at least one load lifting device, in particular a crane hook, wherein a calculation of the position of the load lifting device is effected on the basis of the one or more measured values of at least one measuring device and one or more data characterizing the stiffness of the crane. The present disclosure also relates to a crane controller and a crane for carrying out the method according to the present disclosure.

Claims

1. A system for a crane, comprising: at least one measuring device at the crane supplying one or more measured values; and a crane controller having memory with instructions for control of the crane, the instructions comprising instructions for receiving the one or more measured values, calculating a position of at least one load lifting device based on the received one or more measured values and further based on a model of the crane stored in the memory of the crane controller in which an elasticity of a supporting device of an undercarriage of the crane is modeled via vertically oriented spring elements arranged at ends of the supporting device, and adjusting operation of the crane based on the calculated position.

2. The system according to claim 1, wherein the spring elements are spring damper elements.

3. The system according to claim 1, wherein in the model of the crane, individual support arms or associated support cylinders of the supporting device are modeled as resilient or damping elements.

4. A multi-crane system, comprising: a first crane, comprising at least one measuring device at the first crane supplying one or more measured values of the first crane, and a first crane controller having memory with instructions for control of the first crane, the instructions comprising: instructions for receiving the one or more measured values of the first crane, determining a position of at least one first load lifting device based on the received one or more measured values of the first crane, wherein a first calculation of the position of the first load lifting device is effected on the basis of the one or more measured values of the first crane and further based on a model of the first crane stored in the memory of the first crane controller, and adjusting operation of the first crane based on the calculated position, wherein the model of the first crane is based on a bend of a tower element of the first crane, a bend of a boom element of the first crane, and a spring movement of a supporting device of the first crane, and wherein the model of the first crane is further based on a cable sag and a cable elongation of at least one hoisting cable of the first crane; and a second crane coupled with the first crane.

5. The system according to claim 4, wherein the second crane and the first crane are coupled to a common load.

6. The system according to claim 5, wherein the second crane comprises at least one measuring device at the second crane supplying one or more measured values of the second crane, and a second crane controller having memory with instructions for control of the second crane, the instructions comprising: instructions for receiving the one or more measured values of the second crane, determining a position of at least one second load lifting device based on the received one or more measured values of the second crane, wherein a second calculation of the position of the second load lifting device is effected based on the one or more measured values of the second crane and further based on a model of the second crane stored in the memory of the second crane controller, and adjusting operation of the second and first cranes based on the calculated position, wherein the model of the second crane is based on a bend of a tower element of the second crane, a bend of a boom element of the second crane, and a spring movement of a supporting device of the second crane, and wherein the model of the second crane is further based on a cable sag and a cable elongation of at least one hoisting cable of the second crane.

7. The system according to claim 4, wherein the spring movement of the supporting device of the first crane is modeled via vertically oriented spring elements only arranged at opposite ends of the supporting device.

8. The system according to claim 7, wherein the spring elements are spring damper elements.

9. A system for a crane, comprising: at least one measuring device at the crane supplying one or more measured values; and a crane controller having memory with instructions for control of the crane, comprising: instructions for receiving the one or more measured values, determining a position of at least one load lifting device based on the received one or more measured values, wherein a calculation of the position of the load lifting device is effected based on the one or more measured values and further based on a model of the crane stored in the memory of the crane controller, and adjusting operation of the crane based on the calculated position, wherein the model of the crane is based on a bend of a tower element, a bend of a boom element, and a spring movement of a supporting device, wherein the spring movement of the supporting device is modeled via vertically oriented spring elements arranged at ends of the supporting device, and wherein the model of the crane is further based on a cable sag and a cable elongation of at least one hoisting cable.

10. The system according to claim 9, wherein the at least one measuring device of the crane comprises one or more strain gauges.

11. The system according to claim 10, wherein at least one strain gauge is arranged at the boom element.

12. The system according to claim 10, wherein at least one strain gauge is arranged at the tower element.

13. The system according to claim 9, wherein the at least one measuring device comprises a sensor unit at a retracting mechanism for measuring an unwound cable length and/or at least one sensor unit at a luffing gear for measuring an erection angle.

14. The system according to claim 9, wherein in the model of the crane, the crane is modeled via a plurality of elastic beams.

15. The system according to claim 9, wherein in the model, the boom element is modeled as a beam.

16. The system according to claim 9, wherein in the model, the tower element is modeled as a beam.

17. The system according to claim 9, wherein the tower element is a first tower element, wherein in the model, an undercarriage of the crane and a turntable mounted thereon are each modeled as horizontal beams, and wherein the first tower element and a second tower element are modeled as two vertical beams put together.

18. The system according to claim 9, wherein the spring elements are spring damper elements.

19. The system according to claim 9, wherein in the model of the crane, individual support arms or associated support cylinders of the supporting device are modeled as resilient or damping elements.

Description

BRIEF DESCRIPTION OF THE FIGURES

(1) FIG. 1 shows a sketched crane model for calculating the exact position of a load lifting device.

(2) FIG. 2 shows a calculation flow diagram for determining the position of the load lifting device.

(3) FIG. 3 shows a crane system.

DETAILED DESCRIPTION

(4) The method according to the present disclosure will be illustrated in more detail with reference to a conventional crane. The crane comprises a vertical crane tower which is mounted on a turntable rotatable relative to the undercarriage. The undercarriage is designed with a corresponding supporting device of individual support arms and corresponding support cylinders for operating the support arms. The turntable is connected with the undercarriage via a slewing ring. Furthermore, the crane comprises a boom which is luffably attached to the crane tower by means of a luffing gear. The hoisting cable extends proceeding from the cable winch via a plurality of cable pulleys at the crane tower over the tower tip up to the tip of the boom system. At the end, a crane hook is attached as load lifting device. The hoisting cable can be divided into three individual cable pieces, in particular the cable portion along the crane tower, the cable portion between tower and boom tip, and the cable portion between boom tip and crane hook, wherein the cable pieces generally are designed as block and tackle system.

(5) The crane furthermore has a crane controller which at least is responsible for the essential control tasks. The controller may include computer readable storage medium including code stored therein for carrying out the methods described herein, and generating actions such as calculating a position of the load lifting device, and adjusting crane operation or displaying information based on the calculated position. Thus, a part of the control tasks requires that the controller knows about the actual position of the load or the load lifting device. For this purpose, the controller has a corresponding module which determines the current position of the load lifting device during operation of the crane, and adjusts crane operation or displays crane information based on the determined current position.

(6) So far, the height of the crane hook has been calculated as a function of the radial distance of the crane hook to the crane, i.e. the crane outreach, on the basis of the geometric relations of the crane structure. There has always been assumed a rigid crane model, which always maintains its original geometric configuration. However, the crane deformations occurring in reality due to the applied forces, in particular the load mass, only are considered insufficiently or neglected completely. Disadvantageously, this leads to considerable inaccuracies in the position determination.

(7) The method according to the present disclosure, which is carried out by the crane controller, on the other hand pursues the approach of providing for a more exact position determination of the crane hook, in that a more realistic calculation becomes possible by taking into account one or more data characterizing the deformation of the crane. For this purpose, the crane controller provides a suitable software module which models the crane via the crane model shown in FIG. 1 by way of example. The model may be generated via force and moment balances, including system dynamics such as masses, stiffness, damping, geometry, moments of inertia, etc. The model may be simulated in real time in the controller, such as via the multi-crane system of FIG. 3, showing a first crane 310, a second crane 312 coupled to controller 314. Each crane includes sensors 320, 324, and actuators 322, 326 that may be adjusted based on the crane models and the respective stiffnesses of each of the cranes. The first and second cranes may lift a common load, or separate loads within each others workspace.

(8) In one example, the elasticity of the supporting device 2 including the support arms and support cylinders is modeled via vertically oriented spring damper elements which are meant to simulate a resilient movement along the spring axis.

(9) The crane body itself is modeled via a plurality of elastic beams, wherein the undercarriage 1 and the turntable 3 mounted thereon are modeled as horizontal beams and the crane tower 4 is modeled of two vertical beams put together. The boom 5 modeled as beam is luffably articulated to the crane tower 4 and extends away from the crane tower 4 proceeding from the articulation point with the boom erection angle 9 with respect to the horizontal. In addition the generated crane model takes account of the extensibility of the hoisting cable, wherein in particular a cable sag 6, 7 is assumed at the cable pieces along the crane tower and between tower and boom tip and is modeled correspondingly.

(10) The boom erection angle 9 is detected via a measuring device arranged at the crane, in particular at the luffing gear, and communicated to the crane controller. In addition, the hook mass 10 or load mass is detected via a further measuring device and the corresponding measured values are communicated to the crane controller. The hoisting cable winch 11 provides additional information which relates to the unwound cable length of the hoisting cable. Preferably, the winch position and/or the position of one or more cable pulleys is employed for determining the cable length.

(11) Beside the hook mass 10 and the resulting deformations of the beams, i.e. of the undercarriage 1, the turntable 3 as well as the crane tower 4 and the boom 5, and the spring or damping movement of the support system 2, the boom angle 9 determines the radius R. The hook height H then can be determined by the additional information of the cable winch 11 and the modeled cable sag 6, 7. The calculation of the corresponding boom bend of the crane components 1, 3 to 5 modeled as beams is effected by a measurement of the load hanging at the hook and the respective position.

(12) FIG. 2 shows a calculation flow diagram which shows a chronological order of the individual method steps.

(13) At the beginning, the load mass at the crane hook 10 is determined via a measuring device. Taking into account the applied forces, in particular the weight force of the load mass, the necessary data characterizing the crane stiffness are determined by means of the crane model. The data comprising the deformation or bend of the beams of the crane components 1, 3 to 5 relate to the spring movement of the supporting device 2. By transformation of said values, the position of the crane hook 10 can be determined in radial direction R.

(14) By means of the distance R and the additional information on the condition of the hoisting cable, the actual course of the hoisting cable, in particular possible cable curves and the cable elongation of the hoisting cable, can be simulated rather accurately and be used for calculating the height of the load above the crane floor space. Proceeding from the radial distance R and this additional information, a value H for the vertical hook height H can be determined by means of calculation.

(15) Taking into account the deformation parameters and the exact course of the hoisting cable and its elongation leads to a position determination of the crane hook 10 which is more exact as compared to the prior art. In addition, the model-based method does not require an additional sensor unit for detecting certain parameters. Beside the load mass merely the boom erection angle 9 of the boom 5 must be determined. The measuring device necessary for this purpose usually are present anyway. By a software update of the crane controller, an existing crane system can be retrofitted for carrying out the method according to the present disclosure.

(16) In addition, it is possible not to calculate the beam bend on all or individual beams, but determine the same via installed DMS elements, in order to then be able to supply exact measured values to the crane model.