An arrangement, a crane and a method for operating a crane

Abstract

An arrangement comprising • a lifting arrangement, having at least two crane arms articulately jointed to each other, one of the arms being configured to allow attachment of at least one hoisting device, and at least one actuator for driving at least one of the arms • a human-machine-interface for receiving operating instructions for a desired movement of at least one part of the lifting arrangement • at least one sensor for detecting a momentary geometrical state of at least one part of the lifting arrangement • at least one computing device configured to - receive the operating instructions inputted to the human-machine-interface - based on the geometrical state detected, run a computational model of at least one part of the lifting arrangement to obtain a result - upon receiving an operating instruction, compute at least one first control command based on * the received operating instruction, and * the result of the computational model • at least one control unit which - is operatively connected to or comprises the computing device, and - is configured to open-loop-control movement of the at least one part of the lifting arrangement by * accepting as input the first control command * outputting a second control command to the actuator, the second control command being based on the first control command. A crane having such an arrangement, vehicle comprising a crane, and method for open-loop-control of a crane. A method for adapting a computational model based on an elasticity matrix and a mass matrix of a lifting arrangement.

Description

TECHNICAL FIELD

[0001] The present invention relates to an arrangement, a crane having such an arrangement, a method for open-loop-control of at least one part of a lifting arrangement of a crane and a vehicle having such a crane.BACKGROUND

[0002] It is known that operating parts of a lifting arrangement of a crane such as a crane arm or a load attached to a hoisting device of a crane such that the part or load to be moved does not overshoot a target position or gets into an oscillating motion requires a lot of practice and restricts the possible velocities with which the part or load can be moved.

[0003] To remedy this problem it has been known to close-loop-control movement of a driven part of a crane or a load (cf. WO 2006 / 094322 A2). Such a solution is expensive and complex and does not allow for control of movement in real-time.SUMMARY OF INVENTION

[0004] It is an object to provide an arrangement, a crane having such an arrangement, a method for controlling movement of a part of a lifting arrangement of a crane or of a load attached to a hoisting device of the crane, and a vehicle having such a crane, which minimize the problems of the prior art in a more cost-efficient way and which allow for a more dynamic movement.

[0005] These objects are achieved by an arrangement having the features of claim 1, a crane having such an arrangement, a method having the features of claim 16 and a vehicle having such a crane.

[0006] The arrangement comprises: a lifting arrangement a human-machine-interface for receiving operating instructions for a desired movement of at least one part of the lifting arrangement (e.g. one or more joysticks, a touchscreen, one or more buttons, an augmented-reality-device, a virtual-reality-device, a tablet or cell phone) at least one device for detecting at least one momentary geometrical state of at least one part of the lifting arrangement, e.g. angular orientation of a crane arm around a vertical and / or one horizontal axis or two horizontal axes, degree of extension of a telescopic crane arm at least one computing device (i.e. any electronic device which allows for computation such as a CPU, GPU, FPGA, ASIC, and so on)

[0007] The lifting arrangement has at least the following parts: at least two crane arms articulately connected to each other, one of the at least one crane arms being configured to allow attachment of at least one hoisting device, and at least one actuator for driving at least one of the two crane arms

[0008] The at least one computing device is configured to: receive an input based on operating instructions inputted to the human-machine-interface based on the at least one geometrical state detected by the at least one device for detecting a momentary geometrical state, run a computational model of at least one part of the lifting arrangement to obtain a result upon receiving an operating instruction, run the computational model, and compute at least one first control command based on: the received operating instruction, and the result of the computational model.

[0009] It should be noted that the computational model does not have to run all the time but only after the at least one computing device has received input based on an operating instruction.

[0010] The at least one momentary geometrical state can encompass a time series of geometrical states.

[0011] The at least one control unit is: operatively connected to the at least one computing device or comprises the at least one computing device, and configured to open-loop-control movement of the at least one part of the lifting arrangement by: accepting as input the at least one first control command computed by the at least one computing device outputting at least one second control command to the at least one actuator, the at least one second control command being based on the at least one first control command received as input.

[0012] In the method for open-loop-control of at least one part of a lifting arrangement of a crane, an inputted operating instruction of an operator is used by at least one computing device which is arranged on or in the crane to compute at least one first control signal, the computation of the at least one first control signal by the at least one computing device comprising at least: running a computational model of the at least one part of the lifting arrangement, the computational model receiving as input at least one momentary geometrical state of the at least one part of the lifting arrangement and an input based on the inputted operating instruction outputting the at least one first control signal (either directly to the at least one actuator for open-loop-control of the at least one part of the lifting arrangement, or to a control unit which is arranged on or in the crane and which uses the at least one first control signal to output at least one second control signal).

[0013] Such an arrangement, crane and method allow for an inexpensive solution to the problem of avoiding or, at least minimizing, overshooting, oscillating or other unexpected and unintended movments of a part of the lifting arrangement or a load thereby increasing operational security. Because an open-loop-control is used, no expensive plurality of sensors are necessary and the open-loop-control allows for a more dynamic control of the part or load.

[0014] Although the at least one computing device and the at least one control unit are different logical components they can be realized by one and the same physical component.

[0015] The disclosure also concerns a method according to claim 17 and a computer program according to claim 18.

[0016] Preferred embodiments of the invention are defined in dependent claims.DESCRIPTION OF EMBODIMENTS

[0017] In some embodiments the computing device is configured to run a computational model of: at least one part of the lifting arrangement, and / or a hoisting device attached to one of the at least two crane arms

[0018] In some embodiments the arrangement is a stiff-boom-crane having one crane arm in the form of a crane column which can be turned around a vertical axis and a crane arm articulately connected to the crane column such that it can be turned around a horizontal axis and which can encompass a telescopic further crane arm.

[0019] In other embodiments the arrangement is a knuckle-boom-crane and has one crane arm in the form of a crane column which can be turned around a vertical axis and a system of crane arms one of which is articulately connected to the crane column such that it can be turned around a horizontal axis and at least one futher crane arm which is articulately connected to the crane arm which is connected to the crane column. The system of crane arms can have one or more telescopic arms.

[0020] In some embodiments the at least one computing device is configured to run the computational model in real-time.

[0021] In some embodiments the operating instructions can be used as input of the at least one computing device without any modification. However, in prefered embodiments, a filtering operation is applied to the operating instruction and the filtered operating instruction forms the input for the at least one computing device. The filtering operation aims to smoothen rapid operating instructions of an operator which can happen, e.g. if an operator rapidly flips a joystick.

[0022] With regard to the filtering operation, use of a FIR (Finite Impulse Response) filter, possibly of third order, is prefered. The FIR filter also outputs at least the first and second derivatives of the filtered signal.

[0023] No matter which type of filter is used, it is possible to chose parameters of the filter operation, such as windows length, window shape, and so on.

[0024] In some embodiments the at least one control unit is configured to use the at least one first control command as the at least one second control command. In this case it is possible to equate the at least one first control command and the at least one second control command or not to compute the at least second control command at all but use the at least one first control command in its place. This advantageous if there is no at least one computing device present separate from the at least one control unit.

[0025] In some embodiments the at least one control unit is configured to control at least one part of the lifting arrangement or a load attached to a hoisting device of the lifting arrangement by coordinate control, i.e. instead of moving specific actuators individually via separate operating elements of the human-machine-interface, by coordinate control the operator of the lifting arrangement may simply specify the desired direction of movement of a specific part of the lifting arrangement (for example the crane tip) with for example one operating element of the human-machine-interface, and the control unit combines the necessary movements driven by at least one actuator accordingly. In other embodiments the at least one control unit is configured to control at least one part of the lifting arrangement by accepting the human operating instructions to control the individual actuators of the lifting arrangement.

[0026] In some embodiments the lifting arrangement comprises a hoisting device, preferably comprising a rotationally mounted grapple or a hook attached to a cable.

[0027] In some embodiments the arrangement can comprise a device for determining a mass of a load attached to the hoisting device. If there is such a device it is possible to use the mass of a load as an additional parameter in the computational model.

[0028] In some embodiments the at least one actuator comprises at least one hydraulic drive unit.

[0029] In some embodiments the human-machine-interface is configured to accept a selection of a specific part of the lifting arrangement which is to be controlled by the at least one control unit using the at least one control command computed by the computing device and the at least one computing device is configured to compute the at least one control command based on the accepted selection.

[0030] In some embodiments the arrangement comprises a signal input interface which is configured to accept control signals other than from a human operator (e.g. from a signal generator) as input and to make this input available to the at least one computing device. This allows to receive input from automated functions like trajectory planning algorithms.BRIEF DESCRIPTION OF DRAWINGS

[0031] The Figures show schematic views of: Figure 1: Modelling a lifting arrangement of a crane as an elastic system. Figure 2A: A first aspect of modelling a load attached to a hoisting device of a crane as a pendulum. Figure 2B: A second aspect of modelling a load attached to a hoisting device of a crane as a pendulum.

[0032] In the following example an embodiment is discussed in which an oscillating motion of a load attached to a hoisting device of a lifting arrangement is to be minimized.

[0033] The following model can be used (cf. Figure 1):

[0034] In Figure 1, q M designates coordinates of the actuators, q A designates coordinates of crane arms. The elasticity of the crane arms can be determined by assuming an elastic coupling (k 1,2 ) between actuator coordinates and arm coordinates modelled by an elasticity matrix K. The computational model can be given by: M A q ¨ A + K q A − q M = 0

[0035] It is to be noted that further terms can be added, e.g., in order to model nonlinear behavior. This equation can be solved for q̇ M ( q A 3 denotes the third derivation of q A with respect to time): q ˙ M = K − 1 M A q A 3 + q ˙ A

[0036] This means that velocity of actuator coordinates (which are those that can be controlled by the control unit) can be obtained by M A (a generalized mass of the system) and K (a generalized Hooke's constant of the system) which come from the computational model and q A and its derivates which describe the desired movement of the crane arm.

[0037] The mass matrix M A is known for a given lifting arrangement. Elasticity matrix K can be constructed for a given lifting arrangement by determining the difference between q M and q A for different momentary crane geometries and loads, i.e. what is the resultant movement of parts of the lifting arrangement for known driving by the at least one actuator. This determination can be done by doing measurements of a physical lifting arrangement and / or based on theoretical computations taking into account the physical dimensions of the parts of the lifting arrangement and the type of material used for the parts of the lifting arrangement, e.g. the type of steel used.

[0038] By way of example, in order to determine the elasticity matrix K, it is possible to determine the fundamental eigenfrequencies and fundamental eigenmodes of a given lifting arrangement. The parts of the lifting arrangement can be driven by step-wise functions and the mechanical response of the lifting arrangement can be measured or computed. Harmonics of eigenfrequencies can be ignored but can be estimated in order to increase performance of the computational model. Damping can be ignored at this time scale. Once the values of the eigenfrequencies (eigenvalues) are obtained, the entries of K can be determined as an inverse eigenvalue-problem.

[0039] In the following a computational model for a hoisting device and attached load in the form of a pendulum is discussed.

[0040] In Figure 2, for simplicity of explanation, elasticity of the arms of the lifting arrangement can be ignored. Of course, it is possible to use the elastic model of Figure 1 to describe the elasticity of the crane arms also in the example of Figure 2.

[0041] Based on (possibly filtered) operating instructions received by the computing device, the computing device computes velocities of the crane arms and, possibly, applies a filtering operation (as described with respect to Figure 1). The (possibly filtered) operating instructions can be used as input to the mathematical model, which in this case models the lifting arrangement of the crane including a crane tip but not including the hoisting device and load. As a result this describes how the crane tip would move if the operating instructions of the operator were used as second control commands. However, if the crane tip were to be moved without modification of the operating instructions (as in the prior art) this would result in an undesired oscillation of the hoisting device and load.

[0042] In order to minimize undesired oscillation (ideally such that no oscillation occurs) the computing device can compute at least one first control command which modifies the (possibly filtered) operating instructions such that the oscillating motion is minimized. This computation can be done as follows (cf. Figure 2):

[0043] Several degrees of freedom can be considered, such as, e. g. at least one of the following:

[0044] Degrees of freedom q of a possible representation of a system (q SW denotes the position of a rotatable crane column, q HA denotes the position of a first crane arm articulately conncected to the crane column, q KA denotes the position of a second crane arm articulately connected to the first crane arm, q R denotes the radial position of a first modelled joint in cylindrical coordinates, q T denotes the tangential position of a second modelled joint in cylindrical coordinates) can be in a first group of degrees of freedom: q = q SW … q R q T T

[0045] General position of the load in cartesian coordinates described with cylindrical coordinate. q SW,G is the substitute angle for the representation in cylindrical coordinates, which can be used due to deflection of the pendulum point G. r G = r Gx r Gy r Gz

[0046] Substitute position vector of the attachment point of a hoisting device, here chosen as the crane tip E using cylindrical coordinates r E = r Er r Ez q SW

[0047] For setting up the law of conservation of motion, the hoisting device and load are modelled as a spherical pendulum with a point mass. The law of conservation of motion is derived using the second derivative of the general position of the load r G and the force F applied to the point mass caused by rope forces f s and forces due to gravity f G . The forces applied to the point mass are dependent of q R and q T . The resulting system of equations is solved for q R and q T . Furthermore q R and q T are only dependent on r G , ṙ G , r̈ G and g. ma G = F f s , f G

[0048] Substitute vector of the load depending on position of E, the length of the first pendulum part x P and the length from P to the center of mass of the second pendulum part, mass x G and on the two pendulum angles q R and q T r G r E x P x G q R q T = r Gr r Gz q SW , G

[0049] Substitute vector of the load is solved for the substitute vector of the crane tip. Substitution of q R and q T (which are computed in paragraph 46), in the substitute vector of the crane tip, leads to the desired optimization of the crane tip movement. r E r G x P x G q R q T after substitution r E r G r ˙ G r ¨ G x P x G g after differentiating v E r G r ˙ G r ¨ G r G 3 x P x G g

[0050] By applying an inverse kinematic transformation on the obtained speed of the crane tip v E the coordinates q SW , q HA , q KA are obtained, on the basis of which the at least one first control command is computed. This results in a crane tip motion optimized such that oscillation of the load is minimized.

Claims

1. An arrangement comprising: • a lifting arrangement, having at least the following parts - at least two crane arms articulately connected to each other, one of the at least one crane arms being configured to allow attachment of at least one hoisting device, and - at least one actuator for driving at least one of the two crane arms • a human-machine-interface for receiving operating instructions for a desired movement of at least one part of the lifting arrangement • at least one device for detecting at least one momentary geometrical state of at least one part of the lifting arrangement • at least one computing device which is configured to - receive an input based on operating instructions inputted to the human-machine-interface - based on the geometrical state detected by the device for detecting at least one momentary geometrical state, run a computational model of at least one part of the lifting arrangement to obtain a result - upon receiving an operating instruction, running the computational model, and compute at least one first control command based on * the received operating instruction, and * the result obtained by the computational model • at least one control unit which - is operatively connected to the at least one computing device or comprises the at least one computing device, and - is configured to open-loop-control movement of the at least one part of the lifting arrangement by * accepting as input the at least one first control command computed by the at least one computing device * outputting at least one second control command to the at least one actuator, the at least one second control command being based on the at least one first control command received as input.

2. The arrangement of the preceding claim wherein the computing device is configured to run a computational model of at least one of the following • at least one part of the lifting arrangement, • a hoisting device attached to one of the at least two crane arms3. The arrangement of at least one of the preceding claims wherein the at least one computing device is configured to run the computational model in real-time.

4. The arrangement of at least one of the preceding claims wherein the at least one control unit is configured to use the at least one first control command as a pre-control signal for modifying the received operation instruction and to output the at least one second control command based on the modified operation instruction.

5. The arrangement of the preceding claim wherein a filtering device applies a filtering operation to the operating instruction and the filtered operating instruction forms the input for the at least one computing device.

6. The arrangement of at least one of the preceding claims wherein the at least one control unit is configured to use the at least one first control command as the at least one second control command.

7. The arrangement of at least one of the preceding claims wherein the at least one control unit is configured to control at least one part of the lifting arrangement or a load attached to a hoisting device of the lifting arrangement either • by coordinate control, or • by accepting the human operating instructions to control individual actuators of the lifting arrangement8. The arrangement of at least one of the preceding claims wherein the lifting arrangement comprises a hoisting device.

9. The arrangement of the preceding claim wherein the lifting arrangement comprises a device for determining a mass of a load attached to the hoisting device.

10. The arrangement of at least one of the preceding claims wherein the at least one actuator comprises at least one hydraulic drive unit.

11. The arrangement of at least one of the preceding claims wherein the human-device-interface is configured to accept a selection of a specific part of the lifting arrangement which is to be controlled by the control unit using the at least one control command computed by the computing device and the computing device is configured to compute the at least one control command based on the accepted selection.

12. A crane comprising an arrangement of at least one of the preceding claims.

13. The crane of the preceding claim wherein the crane is a knuckle-boom-crane and has one crane arm in the form of a crane column which can be turned around a vertical axis and a system of crane arms one of which is articulately connected to the crane column such that it can be turned around a horizontal axis and at least one futher crane arm articulately connected to the crane arm which is jointed to the crane column, wherein preferably the system of crane arms has one or more telescopic arms.

14. The crane of claim 12 wherein the crane is a stiff-boom-crane having one crane arm in the form of a crane column which can be turned around a vertical axis and a crane arm articulately connected to the crane column such that it can be turned around a horizontal axis and which, preferably, encompasses a telescopic further crane arm.

15. Vehicle, in particular road truck, carrying a crane of one of claim 12 to claim 14.

16. A method for open-loop-control of at least one part of a lifting arrangement of a crane, in which an inputted operating instruction of a human is used by at least one computing device which is arranged on or in the crane to compute at least one first control signal, the computation of the at least one first control signal by the at least one computing device comprising at least: • running a computational model of the at least one part of the lifting arrangement, the computational model receiving as input at least one momentary geometrical state of the at least one part of the lifting arrangement and an input based on the inputted operating instruction • outputting the at least one first control signal - either directly to, or - to a control unit which is arranged on or in the crane and which uses the at least one first control signal to output at least one second control signal to the at least one actuator for open-loop-control of the at least one part of the lifting arrangement.

17. A method for adapting a computational model that is based on an elasticity matrix and a mass matrix of a lifting arrangement to at least one part of a lifting arrangement in which: • operating instructions are carried out by a control unit which is arranged on or in the lifting arrangement to control movement of at least one part of the lifting arrangement • a time series of momentary geometrical states of the at least one part of the lifting arrangement is acquired by at least one computing device which is arranged on or in the lifting arrangement during movement of the at least one part of the lifting arrangement • eigenfrequencies and eigenmodes of oscillating motions of the at least one part of the lifting arrangement during movement of the at least one part of the lifting arrangement are determined from the time series of momentary geometrical states by the at least one computing device • an elasticity matrix representing at least one generalized Hooke's constant of the at least one part of a lifting arrangement is determined as an inverse eigenvalue-problem by the at least one computing device.

18. A computer program product comprising commands which, when executed by at least one computing device which is arranged on or in the lifting arrangement, prompt the at least one computing device to perform a method according to claim 16 or claim 17 from a storage unit which is in or can be brought into data connection with the at least one computing device.

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