EP3409636A1 - Method for damping torsional vibrations of a load-bearing element of a lifting device - Google Patents

Abstract

A method is provided for damping torsional vibrations of a load-bearing element (7) of a lifting device (1), wherein at least one controller parameter is determined on the basis of a torsional vibration model of the load-bearing element (7) as a function of the lifting height (I _H ) and wherein for damping the torsional vibration of the load-bearing element (7) at any stroke height (I _H ) of the at least one controller parameters to this lifting height (I _H ) is adapted.

Description

The subject invention relates to a method for damping a torsional vibration about a vertical axis of a load-receiving element of a lifting device with a damping controller with at least one controller parameter, wherein the load-receiving element is connected to at least three holding elements with a support member of the lifting device and the length of at least one holding element between the load-receiving element and the support element an actuator acting on the at least one holding element is adjusted by the damping controller.

Hoisting devices, in particular cranes, are available in many different embodiments and are used in many different fields of application. For example, there are tower cranes, which are mainly used for civil engineering, or there are mobile cranes, eg for the installation of wind turbines. Bridge cranes are used, for example, as overhead cranes in factory halls and gantry cranes eg for the manipulation of transport containers at transhipment locations for intermodal cargo handling, such as in ports for handling ships on the railroad or truck or on freight yards for handling from the railroad to the truck or vice versa , Predominantly, the goods are stored for transport in standardized containers, so-called ISO containers, which are equally suitable for transport in the three modes of transport road, rail, water. The structure and operation of a gantry crane is well known and is eg in the US 2007/0289931 A1 described using a "ship-to-shore crane". The crane has a supporting structure or a portal on which a boom is arranged. The portal with wheels, for example, is arranged movably on a track and can be moved in one direction. The boom is firmly connected to the portal and the boom in turn a movable along the boom trolley is arranged. For receiving a freight, for example an ISO container, the trolley is connected by means of four cables with a load-receiving element, a so-called spreader. For receiving and manipulating a container, the spreader can be raised or lowered by means of winches, here by means of two winches for two ropes. The spreader can also be adapted to different sized containers.

In order to increase the efficiency of logistics processes, inter alia, a very rapid cargo handling is required, ie, for example, very fast loading and unloading operations of cargo ships and correspondingly fast movement of the load-bearing elements and the gantry cranes as a whole. However, such rapid movement processes can lead to build up unwanted vibrations of the load-bearing element, which in turn delay the manipulation process, since the container is not precise on the intended Place can be placed. In particular, torsional vibrations of the load-bearing element, that is to say vibrations about the vertical axis, are disturbing, since they are difficult to compensate for with conventional cranes by the crane operator. Such torsional vibrations can additionally be caused or even intensified by, for example, uneven loading of the container or by wind influences.

The US 2007/0289931 A1 mentions, among other things, the problem of oscillations around the vertical axis (skew), but does not propose a satisfactory solution. For measuring the deviations of the load-receiving element from a desired position and for measuring the distance of the load-receiving element from the trolley, a target object consisting of light-emitting elements is provided on the load-receiving element and a corresponding CCD camera is provided on the trolley. Angle deviations around the vertical axis (skew), the longitudinal axis (list) and the transverse axis (trim) can thus be determined. To compensate for the deviations, an actuator is provided per tether, with which the length of the tether can be changed. Depending on the deviation (trim, list or skew), the actuators are controlled in different ways, so that the individual tethers are shortened or lengthened and the corresponding error is compensated. The disadvantage here is that the method proposes only a compensation of angular errors, without taking into account the dynamics of a torsional vibration. Thus, no torsional vibrations can be compensated.

The DE 102010054502 A1 proposes to compensate for torsional vibrations of the load-receiving element to arrange a slewing gear between the load-bearing element and tethers. However, this is very complex and therefore expensive, in addition, the payload is reduced by the weight of the slewing gear.

In the publication Quang Hieu Ngo et. al., 2009, skew control of a quay container crane, in: Journal of Mechanical Science and Technology 23, 2009 a control method for the compensation of torsional vibrations of the load-receiving element of a gantry crane is proposed. It is analogous to the US 2007/0289931 A1 arranged on each tether an actuator for changing the rope length and the load-receiving element, an illumination element is arranged, which cooperates for measuring the angular deviation of the load-receiving element with a arranged on the trolley CCD camera. In this case, a mathematical model and an "input-shaping" control method are used to damp the torsional vibration of the load-bearing element. The input-shaping process is a type of feedforward control with which it is possible to adjust the angle of rotation of the load-bearing element. A damping of an existing torsional vibration is therefore not possible. Another disadvantage is that the mathematical model used in the input-shaping method must be very accurate, since there is no way to compensate for parameter deviations.

Accordingly, it is the object of the invention to eliminate the disadvantages of the prior art, in particular a method for damping torsional vibrations of a load-receiving element of a lifting device is to be created.

According to the invention, the object is achieved in that the at least one controller parameter is determined on the basis of a torsional vibration model of the load-bearing element as a function of the lifting height and that for damping the torsional vibration of the load-receiving element at any stroke height, the at least one controller parameter is adapted to this lifting height. This simple method makes it possible to damp a torsional vibration of a load-bearing element at any lifting height without having to manually set the control parameter or parameters of the damping controller. As a result, the operation of the lifting device or a rapid movement and accurate positioning of a load is considerably simplified, which leads to a time savings and thus to an increase in productivity.

Preferably, the load-bearing element is excited to a torsional vibration at a certain lifting height of the load-receiving element, wherein at least one actual rotation angle of the load-receiving element about the vertical axis and an actual actuator position are detected and thus model parameters of the torsional vibration model of the load-bearing element at the given lifting height are identified by an identification method. As a result, unknown model parameters of a selected torsional vibration model can be determined by means of a suitable identification method, whereby an unknown vibration behavior of the load-bearing element can be determined and used to dampen the torsional vibration.

Advantageously, the at least one actuator is actuated hydraulically or electrically, whereby standard components such as e.g. Hydraulic cylinders or electric motors can be used and an existing power supply system can be used.

If at least four holding elements are provided between the load-receiving element and the carrying element, larger loads can be manipulated.

It is advantageous if at least two actuators are provided, in particular an actuator per holding element. As a result, on the one hand a redundancy of the torsional vibration damping can be realized, whereby the reliability can be increased. On the other hand, smaller actuators of lesser inertia can be used, whereby the response time of the damping control can be lowered and the control quality can be increased.

Advantageously, the lifting height is measured by means of a camera system arranged on the carrying element or on the load receiving element or by means of a lifting drive of the lifting device. As a result, the lifting height can be detected very accurately and in a simple manner. The angle of rotation of the load-bearing element is preferably measured by means of a camera system arranged on the support element or on the load-receiving element. With this simple method, the angle of rotation of the load-bearing element can be determined very accurately. A camera system is also relatively easy to retrofit to an existing lifting device.

According to a preferred embodiment, the torsional vibration model is a differential equation of the second order with at least three model parameters, in particular with a dynamics parameter δ, a damping parameter ξ and a path gain parameter i _β . With the mathematical modeling of the torsional vibration system by a differential equation of second order, a simple but sufficiently accurate mapping of the real torsional vibration is created.

It is advantageous if the identification method is a mathematical method, in particular an online least-square method. With this popular mathematical method, model parameters can be determined easily and with sufficient accuracy.

It is advantageous if a state controller with preferably five controller parameters K _I , K ₁ , K ₂ , K _FF , K _{P is} used as a damping controller. This creates a fast and stable damping controller with high control quality. By an integrated feedforward control (controller parameter K _FF ), the leadership behavior can be improved and by an integrator (controller parameter K _I ) to achieve stationary accuracy or model uncertainties can be compensated.

According to a preferred embodiment, a desired rotational angle of the load-receiving element is specified to the damping controller and the damping controller adjusts this desired rotational angle in a predetermined angular range, in particular in an angular range of -10 ° ≤ β _soll ≤ + 10 °. As a result, a desired rotation of the load-receiving element can be achieved whereby loads such as containers can also be positioned on targets that are not precisely aligned, such as, for example, inclined trucks.

Advantageously, an anti-wind-up protection is integrated in the damping controller, wherein the damping controller actuator limitations of the at least one actuator are specified, in particular a maximum / minimum permissible actuator position s _zul , a maximum / minimum allowable actuator speed v _zul and a maximum / minimum allowable actuator acceleration a _{zul of} the actuator. By means of this so-called anti-wind-up protection, inadmissibly high manipulated variables of the at least one actuator can be avoided, which could lead to a destabilization of the damping controller.

• Fig.1 den grundsätzlichen Aufbau einer Hebeeinrichtung anhand eines Containerkrans,
• Fig.2a und 2b ein Lastaufnahmeelement inklusive Last zur Darstellung einer Drehschwingung,
• Fig.3 einen Ausschnitt einer schematischen Hebeeinrichtung,
• Fig.4 eine Reglerstruktur eines Dämpfungsreglers,
• Fig. 5 eine Zustandsschätzeinheit.

The subject invention will be described below with reference to the FIGS. 1 to 4 explained in more detail, the exemplary, schematic and not limiting advantageous embodiments of the invention show. It shows

• Fig.1 the basic structure of a lifting device on the basis of a container crane,
• 2a and 2b a load receiving element including load for representing a torsional vibration,
• Figure 3 a section of a schematic lifting device,
• Figure 4 a controller structure of a damping controller,
• Fig. 5 a state estimator.

Fig.1 shows a lifting device 1 by way of example with reference to a schematic container crane 2, which is used for example for loading and unloading of ships in a port. Usually, a container crane 2 has a supporting structure 3, which is either fixed or movable on the ground. In the case of a movable arrangement, the supporting structure 3 can for example be arranged movably on rails in the Y-direction, as shown schematically in FIG Fig.1 is shown. By this degree of freedom in the Y direction of the container crane 2 is used locally flexible. The supporting structure 3 has a boom 4 which is fixedly connected to the supporting structure 3. On this boom 4, a support member 5 is usually arranged, which is movable in the longitudinal direction of the arm 4, that is in the illustrated example in the X direction, for example, a support member 5 may be mounted by means of rollers in guides. The support element 5 is usually connected by means of holding elements 6 with a load-receiving element 7 for receiving a load 8. In the case of a container crane 2, the load 8 is usually a container 9, in most cases an ISO container having a length of 20, 40 or 45 feet and a width of 8 feet. But there are also load-bearing elements 7, which are suitable to simultaneously accommodate two containers 9 side by side (so-called dual spreader). For the damping method according to the invention, however, the type and design of the load-bearing element 7 is not further relevant; any desired embodiments of the load-bearing element 7 can be used. The holding elements 6 are usually designed as ropes, four retaining elements 6 are arranged on the support member 5 in most cases, but it can also be more or less holding elements 6 may be provided, but at least three holding elements 6. To accommodate a load 8, such as a Containers 9, the lifting height I _H between the support member 5 and the load-receiving element 7 by means of a linear actuator 10 (see Figure 3 ) adjustable, as in Fig.1 shown eg in Z-direction. When the holding elements 6 are designed as ropes, the lifting height I _{H is} usually adjusted by means of one or more winches 10a, 10b as shown schematically in FIG Figure 3 is shown. For manipulating loads 8 or container 9, the lifting device 1 or the container crane 2 can thus be moved in the direction of three axes. Due to rapid movements, uneven loading of the container 9 or wind influences, it may happen that on the holding elements 6 arranged load-receiving element 7 is excited with the container 9 arranged thereon to vibrate, as described below with reference to FIG 2a and 2b is shown. 2a schematically shows a support member 5, on which a load-receiving element 7 incl. Load 8 is arranged by means of four retaining elements 6. The coordinate system shows the degrees of freedom of the load-receiving element 7. The straight double arrows symbolize the possible directions of movement of the load-bearing element 7, wherein the movement in the Y-direction in the example shown by a movement of the entire lifting device 1, the movement in the X direction by movement of the support member. 5 on the boom 4 (lifting device 1 and boom 4 in Fig.1 a not shown) and the movement in the Z direction by changing the lifting height I _H by means of the holding elements 6 and a lifting drive 10 (not shown). The curved double arrows symbolize the possible rotations of the load-bearing element 7 about the respective axis. Twists about the X-axis and the Y-axis can be relatively easily compensated by the user of the lifting device 1 and the container crane 2 and are not described in more detail here. A twist around the Z-axis (ie around the vertical axis) as in Fig. 2b As described at the beginning, it is very disturbing, since, in particular, a torsional vibration of the load-bearing element 7 around the Z-axis would make it difficult or delay the positioning of a load 8 at a specific location, such as on the loading area of a truck or railway wagon.

According to the invention, therefore, a method is provided with which such a torsional vibration of a load-bearing element 7 around the vertical axis can be easily and quickly damped, so that rapid movement of the load-receiving element 7 with load 8 arranged thereon are made possible, which should contribute to an increase in efficiency of goods manipulation. A detailed description of the method is described below with reference to Figure 3 and Figure 4 described.

Of course, the described embodiment of the lifting device 1 as a container crane 2 according to the Fig.1-Fig.3 only to be understood as an example. The lifting device 1 may also be designed differently for the application of the method according to the invention, for example as a hall crane, tower crane, mobile crane, etc. Important is only the basic function of the lifting device 1 and that the lifting device 1 has the essential components for carrying out the damping method according to the invention, as described below.

In Fig. 3 the essential components of a lifting device 1 are shown, here on the basis of the components of a container crane 2. The essential parts of the invention are shown. The structure and operation of such cranes have been described, are well known and therefore need not be specified. According to a preferred embodiment of the invention are between support member 5 (in Figure 3 shown schematically by dashed lines) and load receiving element 7 four holding elements 6a, 6b, 6c, 6d arranged, for example, as high-strength ropes, in particular as steel cables, may be formed. For lifting and lowering of the load-receiving element 7 in the Z direction, ie for adjusting the lifting height I _H , a lifting drive 10 is provided. In the example according to Figure 3 the lifting drive 10 is performed by winches 10a and 10b, wherein on each winch 10a, 10b two holding elements 6a, 6c and 6b, 6d are wound. But there are of course other forms of Hubantriebs conceivable. For carrying out the method according to the invention, at least one actuator 11a, 11b, 11c, 11d for changing the length of the holding element 6 is provided on at least one holding element 6a, 6b, 6c, 6d. Advantageously, however, an actuator 11a, 11b, 11c, 11d is provided on each holding element 6a, 6b, 6c, 6d. Preferably, as in Figure 3 four retaining elements 6a, 6b, 6c, 6d, each with an actuator 11a, 11b, 11c, 11d are arranged on the lifting device 1.

In a linear actuator 10 as in Figure 3 The holding elements 6a, 6b, 6c, 6d are shown guided over deflecting rollers, which are arranged on the load-receiving element 7. The respective free end of the holding elements 6a, 6b, 6c, 6d is fixed to a stationary holding point, for example on the support element 5. An actuator 11a, 11b, 11c, 11d in this embodiment is preferably fixed to a stationary holding point, for example on the support element 5, and the free end of the holding elements 6a, 6b, 6c, 6d on the actuator 11a, 11b, 11c, 11d. This can be adjusted by adjusting the actuator 11a, 11b, 11c, 11d, the length of a holding element 6a, 6b, 6c, 6d, whereby the distance between the support member 5 and the load-receiving element 7 is adjusted.

An actuator 11a, 11b, 11c, 11d can be controlled by a damping controller 12 for changing the length of the corresponding holding element 6a, 6b, 6c, 6d between the carrying element 5 and the load receiving element 7, preferably the actuator 11a, 11b, 11c, 11d at least one desired actuator position s _soll or a desired actuator speed v _{soll should be} specified. At least one actual actuator position s _{ist of} the at least one actuator 11a, 11b, 11c, 11d can be detected by the damping controller 12 for the damping control 12 (damping controller 12 in FIG Figure 3 not shown). The damping controller 12 may be embodied, for example, as a separate component in the form of hardware and / or software, or else implemented in an existing crane control system. The at least one actuator 11a, 11b, 11c, 11d, as will be described in detail later, be controlled by the damping controller 12 so that by changing the actuator position and / or actuator speed on the one hand the load receiving element 7 is excited to a torsional vibration (as in Figure 3 symbolized by the double arrow) or on the other hand be controlled so that a torsional vibration of the load-bearing member 7 is attenuated.

In the illustrated embodiment, the lengths of two diagonally opposite holding elements 6a, 6b between support element 5 and load receiving element 7 by means of the corresponding actuators 11a, 11b are preferably increased to excite or for damping a torsional vibration and the lengths of the two other diagonally opposite holding elements 6c, 6d reduced by means of the corresponding actuators 11c, 11d or vice versa. For example, however, only three holding elements 6 between support element 5 and load receiving element 7 could be arranged and only one actuator 11 for changing the length of one of the three holding elements 6. It is important only that by means of the at least one actuator 11a, 11b, 11c, 11d, the length of at least one retaining element 6a, 6b, 6c, 6d between support member 5 and load-receiving element 7 is variable, so that a torsional vibration of the load-bearing member 7 about the vertical axis, in Figure 3 around the Z-axis, can be excited or damped.

An actuator 11a, 11b, 11c, 11d may be arbitrary, preferably a hydraulic or electrical embodiment is used, which allows a longitudinal adjustment. If, as in Figure 3 shown, actuators 11a, 11b, 11c, 11d are used in the form of hydraulic cylinders, for example, the energy for actuating the actuators 11a, 11b, 11c, 11d can be obtained from an existing hydraulic system. An actuator 11a, 11b, 11c, 11d, however, can also be designed, for example, as a cable winch and electrically controlled, wherein the actuating energy can be obtained from an existing power supply. Other embodiments of an actuator 11a, 11b, 11c, 11d are also conceivable which are suitable for changing the length of a holding element 6 between the carrying element 5 and the load receiving element 7. In particular, an actuator 11a, 11b, 11c, 11d must control the expected forces during the lifting and lowering of a load 8. In order to bring about a required change in length of a retaining element 6a, 6b, 6c, 6d at a certain load, an actuator 11a, 11b, 11c, 11d may, for example, also have an additional transmission gear.

For carrying out the damping method according to the invention, it is provided that at least one actual rotational angle β _{ist of} the load-bearing element 7 about the Z-axis (or vertical axis) can be detected, for example, a measuring device 14 may be provided in the form of a camera system, wherein the support element 5 a Camera 14a and the load receiving element 7, a cooperating with the camera 14a measuring element 14b is arranged, or vice versa. The actual rotational _angle β, but may also be measured in other ways, for example, is important by means of a gyro-sensor, that a measuring signal for the actual rotational _angle β is present, which can be fed to the attenuator 12th It is further provided that the lifting height I _H between the support member 5 and the load-receiving element. 7 can be detected. For example, the lifting height I _H can be detected via the lifting drive 10, for example in the form of a position signal of a cable winch 10a, 10b available in the crane control. The lifting height I _H could also be obtained from the crane control. The lifting height I _H can also be detected by means of the measuring device 14, for example, but can detect, for example, by means of a camera system which _is β both the lifting height _H I and the actual rotational angle. Such measuring devices 14 are known in the prior art, which is why will not be discussed in detail here.

The individual steps of the damping method are described below with reference to Figure 4 described.

Figure 4 shows a block diagram of a possible embodiment of the control structure according to the invention with a damping controller 12, which can be implemented as already explained either as a separate component or preferably in the control of the lifting device 1, and a controlled system 15, which is controlled by the damping controller 12. The damping controller 12 is designed as a state controller 13 in the embodiment shown. But it is basically any other suitable controller used. The controlled system 15 provides the basis Figure 3 The reference variable of the damping controller 12 is a desired rotational angle β _{soll of} the load-bearing element 7 and the manipulated variable is preferably a desired actuator position s _{soll of} the at least one actuator 11a, 11b, 11c, 11d. Alternatively, as a manipulated variable and a target actuator speed v _{should be used} instead of the desired actuator position s _soll . The actual rotational _angle β can be with a measuring device 14, for example, detected by means of a camera system as already described. As feedback, at least the detected actual rotational angle β _{ist of} the load receiving element 7 is supplied to the damping controller 12 (and in the case of the use of the nominal actuator speed v _soll as the manipulated variable also the detected actual actuator position s _is ). It would also be conceivable, in addition, an actual angular velocity _is β and fed into the variable attenuator 12, whereby the damping control could be further improved. From the detected actual rotation angle β _is, of course, can be used when needed, an actual angular velocity _is β or an actual angular acceleration β _is derived, for example by derivation with respect to time.

The actual variables required, that is to say in particular the actual rotational angle β _, and possibly time derivatives thereof, can either be measured directly or can be estimated, at least partially, also in an observer. An advantage of the use of the estimated means of an observer actual values such as an actual turning angle _is β is that wherein A possibly existing and undesirable for the damping control measurement noise of measured values of a measuring device can be avoided fourteenth That's the Main reason why in a preferred embodiment according to Fig. 3 the actual rotational angle β _is measured with a measuring device 14, but an estimated actual rotational angle β _is nevertheless used for the damping control (in addition, an estimated actual angular velocity β _ist could also be used; Fig. 5 ). Here, any suitable and well-known observers, such as a Kalman filter, can be used, which determines estimated values of the required actual variables. In the following, estimated values are marked with ^ if necessary.

It should be noted, however, that the controller structure for the damping method according to the invention is secondary and in principle any suitable controller could be used. Depending on the implementation, the required actual variables can then be supplied as measured values or estimated values to the damping controller 12.

The damping controller 12 has at least one controller parameter, preferably five controller parameters. By means of the regulator parameter (s), the characteristic of the regulation can be adjusted, e.g. Responsiveness, dynamics, overshoot, damping, etc., whereby one of the properties can be adjusted by means of a controller parameter. If several properties are to be influenced, a corresponding number of controller parameters is required. As a result, the system behavior of the controlled system can be adapted.

Die drei Modellparameter dieses Drehschwingungsmodells sind ein Dynamikparameter δ, ein Dämpfungsparameter ξ und ein Streckenverstärkungsparameter i_β, die beispielsweise definiert sind als $\mathrm{\delta }=\frac{{\mathrm{J}}_{\mathrm{\beta }}}{{\mathrm{c}}_{\mathrm{\beta }}\left({\mathrm{l}}_{\mathrm{H}}\right)}$

mit dem Massenträgheitsmoment J_β der Last 8 samt dem Lastaufnahmeelement 7 und $\mathrm{\xi }=\frac{{\mathrm{d}}_{\mathrm{\beta }}}{{\mathrm{c}}_{\mathrm{\beta }}\left({\mathrm{l}}_{\mathrm{H}}\right)}$

mit einer Federkonstanten c_β und einer Dämpfungskonstante d_β des Schwingungssystems. Die Federkonstante c_β wird dabei von der Hubhöhe I_H abhängig modelliert.For the design of a suitable damping controller 12, first the controlled system, that is to say the technical system to be controlled (eg as in FIG Figure 3 shown). In the present case, the torsional vibration behavior of the load-bearing element 7 is mapped around the Z-axis with a torsional vibration model, for example with a 2nd-order differential equation in the mold

The three model parameters of this torsional vibration model are a dynamic parameter δ, a damping parameter ξ and a path gain parameter i _β , which are defined as, for example $\mathrm{\delta }=\frac{{\mathrm{J}}_{\mathrm{\beta }}}{{\mathrm{c}}_{\mathrm{\beta }}\left({\mathrm{l}}_{\mathrm{H}}\right)}$

with the mass moment of inertia J _{β of} the load 8 together with the load-bearing element 7 and $\mathrm{\xi }=\frac{{\mathrm{d}}_{\mathrm{\beta }}}{{\mathrm{c}}_{\mathrm{\beta }}\left({\mathrm{l}}_{\mathrm{H}}\right)}$

with a spring constant and a damping constant c _β d _β of the vibration system. The spring constant c _β is modeled depending on the lifting height I _H.

It should be noted that this torsional vibration model is to be understood as exemplary only and other torsional vibration models could be used which are able to approximate the real torsional vibration.

The model parameters of the torsional vibration model, for example δ, ξ and i _β , may be known, but are generally unknown. Therefore, in a first step, the model parameters can be identified with an identification method. Such identification methods are well known, for example from Isermann, R.Identifikation dynamic systems, 2nd edition, Springer-Verlag, 1992 or Ljung, L .: System Identification: Theory for the User, 2nd edition, Prentice Hall, 2009, so here will not be discussed further. Common to the identification methods is that the system to be identified is excited with an input function (eg a jump function) and the output variable is detected and compared with an output variable of the model. The model parameters are then varied to minimize the error between the measured output and the output calculated with the model. For possibly necessary identification of the damping controller 12 may be used to excite the load-receiving element 7 arranged thereon load 8 in a certain lifting height I _H to a torsional vibration about the Z-axis. For this purpose, a separate excitation controller may be implemented in the attenuation controller 12, for example in the form of a two-point controller. With the two-position controller, the at least one actuator 11a, 11b, 11c, 11d is actuated, for example, as a function of the actual rotational angle β _{ist of} the load receiving element 7 with the maximum possible nominal actuator speed v _soll . This means that, for example, at a rotation _angle β ≥ 0 ° of the load receiving member 7 of the at least one actuator 11a, 11b, 11c, 11d is driven v with the maximum possible negative actuator velocity and β at a rotation angle _is ≤ 0 ° of the load receiving member 7 of at least an actuator 11a, 11b, 11c, 11d is driven with the maximum possible positive actuator speed v. In the case of an embodiment of the lifting device 1 according to Fig. 3 With four holding elements 6a, 6b, 6c, 6d and four actuators 11a, 11b, 11c, 11d cooperating therewith, the excitation advantageously takes place counteracting, for example by activating the actuators 11a, 11b with the maximum possible positive actuator speed v and the actuators 11c, 11d be driven with the maximum possible negative actuator speed v or vice versa. The excitation of the torsional vibration can take place in any but fixed lifting height I _{H of} the load-receiving element 7. From the excited rotational oscillation of the load receiving member 7 of the damping controller 12 determined on the basis of the detected actual rotation angle β _is the load receiving member 7 and the detected actual actuator position s _of the at least one actuator 11a, 11b, 11c, 11d in by means of an identification method, the model parameters of the implemented torsional vibration model the predetermined lifting height I _H. In the case of the above torsional vibration model, the dynamic parameter δ and the damping parameter ξ are preferably first determined and then, preferably at standstill of the at least one actuator 11a, 11b, 11c, 11d (actual actuator speed v _ist = 0), the path gain parameter i _β . As an identification method For example, according to one embodiment of the invention, a mathematical online least-square method is used for identifying the model parameters, but it would also be conceivable to use other methods, for example offline least-squares methods or optimization-based methods.

With the known (previously known or identified) model parameters, a damping controller 12 can now be designed for the torsional vibration model. For this purpose, a suitable controller structure is selected, for example a PID controller or a state controller. Of course, each controller structure has a number of controller parameters K _k , k≥1, which must be adjusted by means of a controller design method so that a desired control behavior results. Such controller design methods are also well known and therefore will not be described in detail. Examples include the frequency characteristic method, the root locus method, the controller design by Polvorgabe and the Riccati method, which of course there are a wealth of other methods. For the present invention, however, neither the specific controller structure nor the specific controller design process are important. The desired control behavior, of course, taking into account stability criteria and other boundary conditions, can be chosen substantially arbitrarily for the invention. For the invention is only essential that the controller parameters are determined depending on the lifting height I _H. This can also be done in various ways.

It would be conceivable to identify the model parameters for different lifting heights I _H and then to determine the controller parameters K _k for the different lifting heights. In this way it is possible to build up characteristic curves of the controller parameters K _k as a function of the lifting height I _H or characteristic diagrams as a function of the lifting height I _H and other variables, such as a moment of inertia J _β . Of course that would be very costly and not very practical. Preferably, therefore, the controller parameters K _{k of} the damping controller 12 are given as a formula-related relationship as a function of at least the lifting height I _H , and possibly other model parameters, ie K _k = f (I _H ) or K _k = f (I _H , .. .). Thus, the controller parameters K _k must be set only for a lifting height I _H and can then be easily converted to other heights I _H. From the formulaic relationship, however, the controller parameters K _k for different lifting heights I _H can also be calculated offline and from this a characteristic curve or a characteristic field can be created, which is then used in a further sequence.

For the damping control, the controller parameters K _k in each time step of the control, adapted to the current lifting height I _H , for example by reading from a map or by calculation. The damping controller 12 then determines with the adjusted controller parameters K _k the manipulated variable which is set with the at least one actuator 11 a, 11 b, 11 c, 11 d in the respective time step. The controller parameters K _k are thus at the current Lifting height I _H adapted to damp torsional vibrations of the load-bearing element 7 at any stroke height I _H optimally

In particular, in the case of a lifting device 1 with a load-bearing element 7 is often common for different loads 8, eg for containers of different sizes, different load-bearing elements 7 or adjustable in size load-bearing elements 7 to use. Of course, this would have an immediate effect on the moment of inertia J _β . Therefore, it may be provided to perform the above procedure for various load-bearing members 7. This would give 7 different controller parameters K _k for different load-bearing elements.

wie oben beschrieben ausgegangen. Die Modellparameter des Drehschwingungsmodells, also z.B. δ, ξ und i_β, werden für eine bestimmte Hubhöhe I_H wie beschrieben identifiziert. Als Reglerstruktur für den Dämpfungsregler 12 wird aufgrund seiner hohen Regelgüte bzw. Regelperformance ein Zustandsregler 13 verwendet, wie in Fig. 4 dargestellt. Als Reglerparameter K_k sind dabei fünf Parameter K_I, K_P, K₁, K₂, K_FF vorgesehen. Für den Entwurf des Zustandsreglers 13 wird das zu regelnde System mit dem Drehschwingungsmodell als Regelstrecke 15 in eine Zustandsraumdarstellung gebracht, beispielsweise in der Form $$\frac{d}{\mathit{dt}}\left[\begin{array}{c}s\\ \beta \\ \dot{\beta }\\ {\mathit{e}}_{\beta }\end{array}\right]=\left[\begin{array}{cccc}0& 0& 0& 0\\ 0& 0& 1& 0\\ \frac{i_{\beta }}{\delta }& -\frac{1}{\delta }& -\frac{\xi }{\delta }& 0\\ 0& -1& 0& 0\end{array}\right]\left[\begin{array}{c}s\\ \beta \\ \dot{\beta }\\ e_{\beta }\end{array}\right]+\left[\begin{array}{c}1\\ 0\\ 0\\ 0\end{array}\right]v$$

The inventive method will be explained below with reference to a concrete embodiment. It is from a torsional vibration model in the form

as described above. The model parameters of the torsional vibration model, eg δ, ξ and i _β can be identified as described for a specific lifting height I _H. As a controller structure for the damping controller 12, a state controller 13 is used because of its high control quality or control performance, as in Fig. 4 shown. In this case, five parameters K _I , K _P , K ₁ , K ₂ , K _{FF are} provided as controller parameters K _k . For the design of the state controller 13, the system to be controlled with the torsional vibration model as a controlled system 15 is brought into a state space representation, for example in the form $$\frac{d}{\mathit{dt}}\left[\begin{array}{c}s\\ \beta \\ \dot{\beta }\\ {\mathit{e}}_{\beta }\end{array}\right]=\left[\begin{array}{cccc}0& 0& 0& 0\\ 0& 0& 1& 0\\ \frac{i_{\beta }}{\delta }& -\frac{1}{\delta }& -\frac{\xi }{\delta }& 0\\ 0& -1& 0& 0\end{array}\right]\left[\begin{array}{c}s\\ \beta \\ \dot{\beta }\\ e_{\beta }\end{array}\right]+\left[\begin{array}{c}1\\ 0\\ 0\\ 0\end{array}\right]v$$

und eine Abweichung e_β zwischen Soll-Drehwinkel β_soll und Ist-Drehwinkel β_ist verwendet. Die Reglerparameter K_k wurden als Funktion der Hubhöhe I_H, die in den Modellparametern $\mathrm{\delta }=\frac{{\mathrm{J}}_{\mathrm{\beta }}}{{\mathrm{c}}_{\mathrm{\beta }}\left({\mathrm{l}}_{\mathrm{H}}\right)}$

und $\mathrm{\xi }=\frac{{\mathrm{d}}_{\mathrm{\beta }}}{{\mathrm{c}}_{\mathrm{\beta }}\left({\mathrm{l}}_{\mathrm{H}}\right)}$

steckt, wie folgt festgelegt. Dabei ist d₀ ist eine Dämpfungskonstante des geschlossenen Regelkreises, d.h. das beinahe ungedämpfte System wird mit Hilfe des Dämpfungsreglers 12 in ein gedämpftes überführt. Die Parameter ω_i bestimmen die Dynamik und das Ansprechverhalten des Regelkreises und sind an die Systemeigenschaften des zu identifizierenden Drehschwingungsmodells gebunden (der Index i ≥0 steht für die Anzahl der Parameter des Dämpfungsreglers, im ausgehführten Beispiel sind das die Paramter ω₀, ω₁, ω₂). Die Dämpfungskonstante d₀ und die Parameter ω_i sind vorzugsweise vorparametriert bzw. vorgegeben, können aber bei Bedarf vom Benutzer adaptiert werden. $$K_p=2d_0{\omega }_0+{\omega }_1+{\omega }_2$$

$$K_1=\frac{1}{i_{\beta }{K}_P}\left(\left(2d_0{\omega }_0{\omega }_1{\omega }_2-\left({\omega }_1+{\omega }_2\right){\omega }_0^2\right)\delta -K_P\right)$$

$$K_2=\frac{1}{i_{\beta }{K}_P}\left(\left(2d_0{\omega }_0\left({\omega }_1+{\omega }_2\right)+{\omega }_0^2+{\omega }_1{\omega }_2\right)\delta +1-{\mathit{\xi K}}_P\right)$$

$$K_I=\frac{1}{i_{\beta }{K}_P}\left({\omega }_0^2{\omega }_1{\omega }_2\delta \right)$$

$$K_{\mathit{FF}}=K_2+\frac{1}{i_{\beta }}$$

As states of the system, the actuator position s, the rotation angle β, the angular velocity

and a deviation e _β between target rotation angle β _soll and actual rotation angle β _is used. The controller parameters K _k were calculated as a function of the lifting height I _H in the model parameters $\mathrm{\delta }=\frac{{\mathrm{J}}_{\mathrm{\beta }}}{{\mathrm{c}}_{\mathrm{\beta }}\left({\mathrm{l}}_{\mathrm{H}}\right)}$

and $\mathrm{\xi }=\frac{{\mathrm{d}}_{\mathrm{\beta }}}{{\mathrm{c}}_{\mathrm{\beta }}\left({\mathrm{l}}_{\mathrm{H}}\right)}$

is set as follows. Here, d ₀ is a damping constant of the closed loop, ie the almost undamped system is converted by means of the damping controller 12 in a muted. The parameters ω _i determine the dynamics and the response behavior of the control loop and are bound to the system properties of the torsional vibration model to be identified (the index i ≥0 stands for the number of parameters of the damping controller, in the example given these are the parameters ω ₀ , ω ₁ , ω ₂ ). The damping constant d ₀ and the parameters ω _i are preferred pre-parameterized or predetermined, but can be adapted by the user if required. $$K_p=2d_0{\omega }_0+{\mathrm{<figure-callout\; id="1"\; label="\omega "\; filenames="imgf0001.png,imgf0002.png"\; state="\{\{state\}\}">\omega </figure-callout>}}_1+{\omega }_2$$

$${\mathrm{<figure-callout\; id="1"\; label="K"\; filenames="imgf0001.png,imgf0002.png"\; state="\{\{state\}\}">K</figure-callout>}}_1=\frac{1}{i_{\beta }{K}_P}\left(\left(2d_0{\omega }_0{\mathrm{<figure-callout\; id="1"\; label="\omega "\; filenames="imgf0001.png,imgf0002.png"\; state="\{\{state\}\}">\omega </figure-callout>}}_1{\omega }_2-\left({\mathrm{<figure-callout\; id="1"\; label="\omega "\; filenames="imgf0001.png,imgf0002.png"\; state="\{\{state\}\}">\omega </figure-callout>}}_1+{\mathrm{<figure-callout\; id="2"\; label="\omega "\; filenames="imgf0001.png"\; state="\{\{state\}\}">\omega </figure-callout>}}_2\right){\omega }_0^2\right)\delta -{\mathrm{<figure-callout\; id="2"\; label="K\; P\; K"\; filenames="imgf0001.png"\; state="\{\{state\}\}">K\; </figure-callout>}}_P\right)$$

$$K_{}$$$${}_2=\frac{1}{i_{\beta }{K}_P}\left(\left(2d_0{\omega }_0\left({\mathrm{<figure-callout\; id="1"\; label="\omega "\; filenames="imgf0001.png,imgf0002.png"\; state="\{\{state\}\}">\omega </figure-callout>}}_1+{\mathrm{<figure-callout\; id="2"\; label="\omega "\; filenames="imgf0001.png"\; state="\{\{state\}\}">\omega </figure-callout>}}_2\right)+{\omega }_0^2+{\mathrm{<figure-callout\; id="1"\; label="\omega "\; filenames="imgf0001.png,imgf0002.png"\; state="\{\{state\}\}">\omega </figure-callout>}}_1{\mathrm{<figure-callout\; id="2"\; label="\omega "\; filenames="imgf0001.png"\; state="\{\{state\}\}">\omega </figure-callout>}}_2\right)\delta +1-{\mathit{\xi K}}_P\right)$$

$$K_I=\frac{1}{i_{\beta }{K}_P}\left({\omega }_0^2{\mathrm{<figure-callout\; id="1"\; label="\omega "\; filenames="imgf0001.png,imgf0002.png"\; state="\{\{state\}\}">\omega </figure-callout>}}_1{\mathrm{<figure-callout\; id="2"\; label="\omega "\; filenames="imgf0001.png"\; state="\{\{state\}\}">\omega </figure-callout>}}_2\delta \right)$$

$$K_{\mathit{FF}}={\mathrm{<figure-callout\; id="2"\; label="K"\; filenames="imgf0001.png"\; state="\{\{state\}\}">K</figure-callout>}}_2+\frac{1}{i_{\beta }}$$

In the damping controller 12, the controller parameters of the state controller 13 are then calculated on the basis of the current lifting height I _H in each time step of the control and based on the control. So that the torsional vibration of the load receiving element 7 can be effectively damped during a lifting operation, because the SAS 12 automatically to the current lift height I _H adapts.

As a manipulated variable of the control, the damping controller 12 can determine an actuator position s _{soll to be set} or an actuator speed v _soll for the at least one actuator 11a, 11b, 11c, 11d and output it at an interface 16. To this end receives the damping controller 12 via an interface 17, the required actual values, for example the actual position s _of the at least one actuator 11a, 11b, 11c, 11d and the actual rotational _angle β of the load receiving element 7. The time derivative of the actual rotational angle β _is can be detected in the attenuator 12 or is also measured.

Die Zustandsschätzeinheit 20 kann beispielsweise als hinlänglich bekannter Kalman-Filter implementiert sein. Das Drehschwingungsmodell kann dazu auch in der Zustandsschätzeinheit 20 verwendet werden.Alternatively, a state estimator 20 (FIG. Figure 5 ), Be provided in the form of hardware and / or software that β _is the load receiving member 7 from measured actual values, for example of the actual rotation angle determined estimated values of the required input of the variable attenuator 12, here for example-an estimated actual rotational angle β _is and an estimated actual angular velocity

The state estimator 20 may be implemented, for example, as a well-known Kalman filter. The torsional vibration model can also be used in the state estimation unit 20 for this purpose.

The damping controller 12, a target rotation angle β _{is to} set the load receiving member 7 which is controlled by the variable attenuator 12th Normally, a setpoint rotation angle β _soll = 0 is specified, with which torsional vibrations are compensated by a defined zero position. But it can also be a deviating target rotational angle β set _soll be, with which the load-receiving element 7 is controlled by the damping controller 12 and independently of the lifting device 1 to this angle and while also torsional vibrations are damped by this angle. As a result, for example, a load 8, such as a container 9, are rotated in a predetermined angular range and thereby eg unloaded on a loading area of an inaccurately positioned truck. For this purpose, no additional device for rotating the load-bearing element 7 about the vertical axis is required. Depending on the type and design of the lifting device 1 and its components can be adjusted by the damping controller 12, a rotational angle β of the load-receiving element 7 in a range of, for example ± 10 °.

According to an advantageous embodiment of the invention, an anti-wind-up protection is integrated in the damping controller (12), the damping controller 12 being given actuator limitations of the at least one actuator 11, in particular a maximum / minimum allowable actuator position s _zul , a maximum / minimum allowable actuator speed v _zul and a maximum / minimum allowable actuator acceleration a _{zul of} the actuator 11. This integrated anti-wind-up protection of the damping controller 12 can be adapted to the type of or the available actuators 11 of the lifting device 1. For damping the torsional vibration of the load-bearing element 7, the damping controller 12 calculates, as described, a manipulated variable of the at least one actuator 11, for example the desired actuator speed v _soll . If this desired actuator speed v _soll exceeds a maximum permissible actuator limit, for example the actuator speed v _zul , the setpoint actuator speed v _{soll is} limited to this maximum permissible actuator speed v _zul . Without actuator restriction or anti-wind-up protection, it could happen, for example, that the damping controller 12 calculates too high a nominal actuator speed v _soll that the at least one actuator 11 could not follow because of its design. This would lead to a control error and the damping controller 12, in particular the integrated in the damping controller 12 integrator would try to compensate for this control error by the manipulated variable, for example, the target actuator speed v _soll , would be further increased. This "charging" of the damping controller 12 or in particular of the integrated in the damping controller integrator could lead to a destabilization of the damping controller 12, which can be reliably prevented by the integrated anti-wind-up protection. In addition, the target actuator speed v _{soll can} also _{be used to} calculate a desired actuator acceleration a soll and to compare it with a maximum / minimum allowable actuator acceleration a _{zul of} the corresponding actuator 11a, 11b, 11c, 11d. If this maximum / minimum allowable actuator acceleration a _{zul is} exceeded, this can also _be taken into account with a limitation of the desired actuator speed v _soll . This allows different embodiments and sizes of Actuators 11a, 11b, 11c, 11d are taken into account in the damping controller, whereby the method is very flexible applicable to a variety of lifting devices 1.

Claims (12)

Method for damping a torsional vibration about a vertical axis of a load-bearing element (7) of a lifting device (1) with a damping regulator (12) with at least one controller parameter, said load-receiving element (7) having at least three retaining elements (6) with a support element (5) of the lifting device (1) is connected and the length of at least one holding element (6) between the load-receiving element (7) and support element (5) with an actuator (11) acting on the at least one holding element (6) is adjusted by the damping controller (12), characterized in that the at least one controller parameter is determined on the basis of a torsional vibration model of the load-bearing element (7) as a function of the lifting height (I _H ) and that for damping the torsional vibration of the load-bearing element (7) at any desired lifting height (I _H ) the at least one controller parameter adjusts to this lifting height (I _H ) is adapted. A method according to claim 1, characterized in that the load-receiving element (7) at a certain lifting height (I _H ) of the load-bearing element (7) is excited to a torsional vibration that thereby at least one actual rotation angle (β _is ) of the load-receiving element (7) to the vertical axis and an actual actuator position (s _is ) are detected and thus model parameters of the torsional vibration model of the load-bearing element (7) at the given lifting height (I _H ) are identified by means of an identification method. A method according to claim 1, characterized in that the at least one actuator (11) is hydraulically or electrically actuated. Method according to claim 1 or 3, characterized in that at least four holding elements (6) are provided between the load-receiving element (7) and the carrying element (5). A method according to claim 1 to 4, characterized in that at least two actuators (11) are provided, in particular an actuator (11) per holding element (6). Method according to claim 1 to 5, characterized in that the lifting height (I _H ) is measured by means of a camera system (14) arranged on the carrying element (5) or on the load receiving element (7) or by means of a lifting drive (10) of the lifting device (1) , A method according to claim 1 to 6, characterized in that the actual rotation angle (β _is ) of the load-receiving element (7) by means of a, on the support member (5) or on the load-receiving element (7) arranged measuring device (14) is measured, preferably by means of a camera system or gyro-sensors. The method of claim 1 to 7, characterized in that the torsional vibration model is a differential equation of the second order with at least three model parameters, in particular with a dynamic parameter (δ), a damping parameter (ξ) and a system gain parameter (i _β ). A method according to claim 1 to 8, characterized in that the identification method is a mathematical method, in particular an online least-square method. A method according to claim 1 to 9, characterized in that the damping controller (12) is a state controller with preferably five controller parameters (K _I , K ₁ , K ₂ , K _FF , K _P ). A method according to claim 1 to 10, characterized in that the damping controller (12) a desired rotation angle (β _soll ) of the load receiving element (7) is specified and the damping controller (12) the desired rotation angle (β _soll ) of the load receiving element (7). in a predetermined angular range, in particular in an angular range of -10 ° ≤ β _soll ≤ + 10 °. The method of claim 1 to 11, characterized in that in the damping controller (12) an anti-wind-up protection is integrated, wherein the damping controller (12) actuator limitations of the at least one actuator (11) are specified, in particular a maximum allowable actuator position (s _zul ), a maximum allowable actuator speed (v _zul ) and a maximum allowable actuator acceleration (a _zul ) of the actuator (11).

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