EP2502871B1 - Crane control, crane and method - Google Patents

Description

The present invention relates to a crane control of a crane comprising at least a first and a second cable harness for lifting a load according to the preamble of claim 1. The present invention also relates to a method for controlling the interlocking of a crane according to the preamble of claim 10. Die Crane control controls the interlocking of the crane. In particular, the crane is a jib crane which has a boom which is pivotable about a horizontal axis and which is articulated on a tower rotatable about a vertical axis. For this purpose, a luffing mechanism and a slewing are provided as interlockings. The rope for lifting the load thereby runs over the tip of the jib, in particular via one or more deflection rollers arranged there, so that the load can be moved in the radial direction by rotating the tower in the tangential direction and by rocking the jib. In the embodiment of the invention, both cable strands extend from the tip of the cantilever to a receiving element such as a hoe. The length of the rope is adjustable by a corresponding drive to move the load in the vertical direction. In particular, the crane control according to the invention generally relates to rotary cranes, as well as mobile harbor cranes, ship cranes, off-shore cranes, mobile cranes and crawler cranes.

Out DE 100 64 182 and DE 103 24 692 Whose entire contents form part of the present application, crane controls are known whose control and automation concepts prevent the pendulum movement of the load on the rope during a movement of the crane.

Out DE 100 29 579 and DE 10 2006 033 277 , whose contents also form part of the following application, crane controls are still known, which prevent a torsional vibration of the load on the rope.

The FR 2 445 299 A1 discloses a crane control system for controlling the interlockings of a crane, which has at least a first and a second cable harness for lifting the load, with a load oscillation damping, which is suitable for damping spherical pendulum vibrations of the load. There are provided a first and a second sensor unit, which are associated with the first and the second cable strand to determine the respective cable angle. The load oscillation damping has a control, in which enter the determined by the first and the second sensor unit rope angle.

In the crane controls mentioned above, gyroscope units are used to determine the load oscillation, which are arranged in the crane hook and determine the angular speed of the cable. The rope angle is determined via an observer circuit, which integrates the movement of the rope. In order to be able to compensate for the resulting offset, it is assumed that a freely oscillating pendulum whose rest position corresponds to a vertical rope angle. Although such a procedure is well suited for the rope pendulum damping, since this especially the movements of the rope with free swinging of the load on the rope must be monitored. However, a determination of the absolute orientation of the rope, especially before the load can swing freely, is neither provided nor possible in the known crane controls. Farther Known sensor arrangements and crane controls had the disadvantage that disturbances such as the rope field rotation in the load swing damping for damping the spherical pendulum vibrations of the load were disregarded.

Known systems, such as. B. in cranes with a movable only in the horizontal direction trolley are used and which Meßkamerasysteme use to determine the absolute rope angle, but are not used in particular in jib cranes. Measuring camera systems must always be arranged directly behind the rope fixing point in order to be able to determine the rope angle. at Jib cranes, in which the rope is movably guided over a deflection roller arranged on the boom, however, no rope fixation point is given, since the rope exit point also changes with the rope angle. Transducers, which mechanically determine the rope angle relative to the boom, are equally unsuitable for measuring the absolute rope angle, since, firstly, they work inaccurate and, moreover, lead to incorrect results when the crane is deformed. In addition, all these systems always determine only the rope angle relative to the boom, and would thus only indirectly suitable for determining the absolute rope angle, so that was previously dispensed with such solutions entirely.

The crane operator must therefore continue to align the crane by hand and in sight before the stroke or at the beginning of the stroke so that the rope is aligned substantially vertically. However, especially at the great distance from the load, this is often extremely difficult, so that deviations of the rope angle from the vertical result, which lead to unwanted vibrations when lifting the load. The same problem arises when, due to an imbalance of the load, the rope is vertically aligned before the stroke, but the rope angle is changed when lifting the load by the movement of the center of gravity of the load below the load receiving point. The yielding of the crane structure under the load when lifting the load can change the rope angle unintentionally. In the case of offshore cranes, the additional problem arises that the rope angle can be changed by a relative movement of a ship carrying the load to the offshore crane.

A crane control is provided, which allows easier and safe alignment of the crane, in particular before and during the lifting of the load. It is another object of the present invention to provide an improved damping of the spherical pendulum vibrations of the load.

According to the invention this object is achieved by a crane control according to claim 1. This preferably has a sensor unit for determining a Rope angle relative to the direction of gravity force. By means of this sensor unit, the cable angle can be determined directly relative to the direction of gravitational force, so that the vertical alignment of the cable is considerably simplified. This also increases the security of the hub.

The sensor unit usually has an element which aligns under the influence of the gravitational force and by which the angle of the rope relative to the direction of gravitational force can be determined. In particular, any type of electric dragonfly can be used. In the simplest embodiment, the sensor unit can only determine whether the rope is vertically aligned or not. In more elaborate embodiments, the direction of the deviation from the vertical and in further embodiments the value of the deviation from the vertical can also be determined.

The sensor unit can thereby determine the cable angle in at least one direction relative to the direction of gravity, e.g. in the radial or in the tangential direction, in order to be able to determine a deviation of the rope angle from the perpendicular in this direction and to be able to compensate if necessary. Advantageously, the cable angle is determined both in the tangential and in the radial direction, since only in this way is an actual vertical alignment of the cable possible. For this purpose, the sensor unit can have at least two sensors, each of which serves to determine the radial or the tangential cable angle relative to the gravitational force direction. By such a sensor unit, a precise alignment of the crane when lifting the load is possible, so that the rope is aligned vertically. Similarly, the sensor unit can be used for monitoring and security functions.

According to the invention, the control of the crane control according to the invention is non-linear. Such a non-linear control is of particular advantage, since in particular for jib cranes, the entire system of crane, interlockings such. As hydraulic cylinders and load is non-linear and thus considerable errors occur in a purely linear control. The entire control path from non-linear control and the non-linear behavior of the crane, however, in turn according to the invention results in a linear path, so that the control of the system is considerably simplified. Furthermore, the regulation is based on the inversion of a non-linear physical model of the movement of the load as a function of the movements of the interlockings, whereby the inversion serves as the input of the movement of the load in order to control the interlockings.

Advantageously, this physical model is a nonlinear model, so that its inversion results in the inventive non-linear control. The combination of the inverted physical model and the actual movement of the load as a function of the movements of the interlockings then again results in the linear path described above. Input variables of the physical model are the state vector of the crane. Based on these inputs, the non-linear model then indicates the movement of the load as the output. By inverting such a system, the movement of the load serves as an input to drive the interlocking of the crane.

Furthermore advantageously, in addition to the sensor unit for determining a cable angle relative to the direction of gravitational force, at least one gyroscope unit for measuring a cable angular velocity is furthermore provided. In particular, this gyroscope unit can continue to be used for vibration damping oscillating load are used, for which the sensor unit for determining the rope angle relative to the gravitational force direction usually can not provide sufficiently accurate data. The orientation of the crane can then be carried out first based on the sensor unit for determining the cable angle relative to the direction of gravity force until the load hangs freely on the rope. Thereupon, the automatic cable oscillation damping, which operates on the basis of the gyroscope unit, can be switched on.

The gyroscope unit measures the cable angular velocity in at least one direction, e.g. in the radial or in the tangential direction. Advantageously, however, both the tangential and the radial cable angular velocity are determined, for which purpose the gyroscope unit advantageously has at least two appropriately arranged gyroscopes.

The crane control comprises at least two sensor units for determining the cable angles relative to the direction of gravitational force, which are assigned to different cable strands. As a result, a cable field rotation, which corresponds to a rotation of the load, are taken into account. If only one sensor unit were used here with several cable strands, however, a cable field rotation would lead to corrupted measured values.

In particular, the cable field rotation, and thus the rotation of the load, can be determined by the at least two sensor units. This makes it possible, before the start of the stroke and the cable field twist z. B. offset by a rotation of the lifting device relative to the load.

Furthermore, advantageously at least two gyroscope units are provided for measuring the cable angular velocities, which are assigned to different cable strands. So the rope field twist z. B. also be taken into account in the vibration damping drive.

Furthermore advantageously, the sensor unit and / or the gyroscope unit are arranged on a cable follower element, which is connected in particular via a gimbal connection with a jib of the crane and which is guided on the cable. The cable follower element is preferably connected by the gimbal connection with the boom head of the crane and follows the movements of the rope on which it is guided by rollers. By measuring the movement of the cable follower element so the movements of the rope can be determined.

If the crane has at least two cable strands for lifting the load, advantageously at least two cable follower elements are provided, which are assigned to different cable strands. Since the hook of the crane usually depends on several cable strands, so also rope field distortions can be considered.

Further advantageously, the crane control according to the invention comprises a display unit for displaying a deviation resulting from the measured cable angle, in particular for displaying a cable angle relative to the direction of gravitational force and / or a resulting horizontal deviation of the load. This display considerably facilitates the crane operator's alignment of the rope in a vertical position.

Advantageously, the display shows a vertical cable position optically and / or acoustically. This makes it possible for the crane operator to align the rope accordingly.

Further advantageously, the display further indicates the direction in which the rope deviates from the perpendicular. Further advantageously, the display also indicates the absolute value of the deviation. It is conceivable z. Example, a graphical display in which the angle of the rope relative to the direction of gravitational force and further advantageously displayed the maximum permissible rope angle become. Alternatively or additionally, the horizontal deviation of the load from the position at which the load would be located in the vertical cable position can be displayed, advantageously together with the maximum permissible horizontal deviation. This allows the crane operator to work with well-known distance indications and to align the crane more easily.

Further advantageously, a warning device is provided, which warns the crane operator when exceeding an allowable value range for a resulting from the measured rope angle deviation, in particular for the rope angle relative to the gravitational force direction and / or for the horizontal deviation of the load, in particular by an optical and / or acoustic signal. In this way, the crane operator can react when exceeding the permissible value range and avoid damage to the crane structure or accidents. For example, the crane operator can stop the movement of the crane when exceeding the permissible angle range, or, if it is an off-shore crane, in which the z. B. load on a ship is moved away by a relative movement of the ship relative to the crane from the off-shore crane, avoid by a partial release of the rope or the slewing gear of the crane overload.

Further advantageously, a safety device, in particular an overload protection, is provided, which automatically in the control when exceeding an allowable value range for a resulting from the measured rope angle deviation, in particular for the rope angle relative to the gravitational force direction and / or for the horizontal deviation of the load engages the crane, in particular to prevent overload of the crane. In particular, the rope angle relative to the gravitational force direction can thus be included in the automatic load moment limitation of the crane. This considerably increases the safety of the operation, since known load torque limitations could not take this parameter into account and the loads resulting from an excessive inclination of the cable had to be taken into account solely via the other transducers.

Advantageously, the overload protection stops the movement of the crane automatically. This prevents overloading of the crane structure due to excessive skewing of the cable. Likewise, accidents can be avoided by the safety device in addition to the overload of the crane, e.g. if, when the permissible value range is exceeded, lifting of the load is automatically prevented in order to avoid excessive swinging when the load comes free.

In particular, when it comes to an off-shore crane, the overload protection, the movement of the crane and / or the rope also at least partially release, the release here is advantageously controlled with a certain counter-force. Hooked z. As the hook of the crane on a ship, which is expelled from the off-shore crane, can be such. B. the rope or the rotational movement of the crane are released in a controlled manner to prevent overloading of the crane. The sensor unit for determining a cable angle relative to the direction of gravitational force here results in a very reliable overload protection, while known overload protection relied solely on a cable force sensor, by which an overload case can be difficult to distinguish from a load case.

Further advantageously, the crane control according to the invention, in particular the warning device and / or the overload protection, but additionally evaluates data from a cable force sensor. As a result, the data can be checked by the sensor unit for determining the cable angle relative to the direction of gravitational force, so that an additional security is provided by a redundancy, in particular in an automatic intervention of the crane control in the movement of the crane.

Advantageously, the cable field rotation of the at least two cable strands is determined. Since in a pure rotation of the load, the outer cables are deflected in opposite directions, respectively, without the load would be deflected from the vertical, this Seilfeldverdrehung advantageously taken into account in the determination of the actual cable angle. The rope angle, which is used in the display, the warning device and / or the overload protection, thereby corresponds to the actual deflection of the load relative to the gravitational force direction, so that oscillation of the load can be effectively prevented and any Seilfeldverdrehungen not lead to incorrect values.

Advantageously, the crane control according to the invention comprises a display unit for displaying the cable field rotation. Thus, the cable field rotation itself can also be displayed on the display, so that it can be compensated by driving a corresponding rotor unit on the load receiving device. Likewise, the cable field twist can advantageously be included in the control of the warning device and the overload protection.

In the crane control according to the invention therefore advantageously a warning device is provided, which warns the crane operator when exceeding an allowable value range for the cable field rotation, in particular by an optical and / or acoustic signal. Thus, the crane operator is warned against a swinging of the load when lifting with a twisted rope field.

In the crane control according to the invention is also advantageously a safety device, in particular an anti-rotation, provided which automatically engages in an excess of an allowable value range for the Seilfeldverdrehung in the control of the crane. For example, a lifting of the load can be automatically prevented in case of excessive rotation of the rope field.

Further advantageously, the crane control according to the invention has an automatic load oscillation damping. In particular, as a result, the movement of the crane can be controlled so that during a movement of the crane, a swinging of the free-swinging load is prevented. The sensor unit for determining the cable angle relative to the direction of gravitational force can thereby at the beginning of the stroke be used for vertical alignment of the rope, while the load swing damping starts when the load is hanging freely on the rope. Thus, the correct orientation of the rope can prevent the load from swinging during lifting, while the load swing damping prevents the load from oscillating as it moves in the horizontal direction.

Advantageously, the load oscillation damping is based on the data of at least one gyroscope unit. Since the cable angular velocity can be determined with a gyroscope, it is particularly well suited for use in load swing damping.

Advantageously, the sensor unit is used for determining the cable angle relative to the direction of gravitational force for monitoring and / or calibration of the gyroscope unit. In particular, if the stroke is started with an inclined cable position and a supported load, the load-swing damping, which usually starts from a free-running load, would otherwise start with incorrect values. The sensor units or gyroscope units can also be used for mutual monitoring in order to detect malfunctions.

Advantageously, a function for automatic alignment of the crane is further provided by which the rope is aligned perpendicular to the load. The crane operator no longer has to do this manually with the crane. B. based on the display, but this is done automatically with a corresponding request from the crane operator via an operating unit. Advantageously, in this case a security function is provided which z. B. cooperates with a rope force sensor to prevent in case of malfunction of the sensor unit for determining the rope angle relative to the direction of gravity force an uncontrolled movement of the crane.

Further advantageously, a function for automatic alignment of the crane is provided, compensated by which a rope field twist becomes. This advantageously controls a rotor unit on the load receiving device, for example on the spreader, through which the connected to the ropes part of the load bearing device can be rotated relative to the load.

Further advantageously, the crane control according to the invention has a memory for storing load data on the basis of the rope angle, which the life calculation and / or documentation z. B. of improper use. Such a machine data acquisition of the cable position for load spectrum determination and documentation thus enables a more accurate life cycle calculation and thus increased safety at saved costs.

The present invention further comprises a method for controlling the interlocking systems of a crane according to claim 10. Advantageously, the radial and / or tangential rope angles are determined relative to the gravitational force direction.

In particular, thereby the alignment of the crane before and when lifting the load is considerably simplified. Advantageously, in addition to a cable angle, which corresponds to the actual deflection of the load against the perpendicular, in addition the cable field rotation is determined when several cable strands are used to lift the load. For this purpose, the cable angles of at least two cable strands are determined relative to the direction of gravitational force. From this data can then be determined both the cable angle, which the deflection of the load, as well as the cable field rotation, which corresponds to the rotation of the load.

Advantageously, the rope is brought into a vertical orientation before lifting the load. This can be prevented by an inclination of the rope when lifting the load this slips laterally, uncontrolled twisted by uneven resting on the surface or already performs a pendulum movement when lifting. The vertical orientation of the load can be z. B. by the crane operator based on the display of the cable angle according to the invention relative to the direction of gravitational force. It is also conceivable that this alignment is carried out automatically by the crane control as already described.

Further advantageously, prior to lifting the load, the cable field twist is brought to zero to avoid rotation of the load during lifting. This is done z. B. by corresponding rotation of the load on the load receiving means by means of a rotor assembly.

Even during the lifting process deviations of the rope angle from the vertical can result due to different effects. Advantageously, therefore, a deviation of the cable angle is compensated by the vertical even during the lifting of the load. Advantageously, this is determined during the lifting of the load of the rope angle relative to the direction of gravity force, so that any deviations occurring during the lifting process can be compensated.

Advantageously, an imbalance of the load is determined when lifting the load by determining the occurring deviation of a rope angle of the vertical. If the load is unbalanced, ie if the center of gravity of the load is not below the load pick-up point, the load pick-up point initially moves above the center of gravity when lifting the load so that the rope angle changes. This change in the rope angle, the imbalance of the load can be determined and possibly compensated. Such an imbalance of the load can also be displayed, so that it can be compensated by the crane operator. It is also conceivable to automatically compensate for such an imbalance.

Advantageously, the imbalance of the load is thereby compensated on the basis of the deviation of a cable angle from the vertical by a movement of the load on the load receiving means, in particular on the spreader. The spreader serves to receive containers and has a longitudinal adjustment, by which the load receiving point can be adjusted relative to the container. The crane operator can now z. B. based on the deviation of the rope angle of the perpendicular, which is formed when lifting the load by the imbalance and is displayed on the display according to the invention, move the load receiving point on the load receiving means and so compensate for the imbalance. In addition, if the imbalance of the load is determined and displayed, this facilitates the work of the crane operator. It is also conceivable that an automatic compensation of the imbalance takes place.

Such compensation of the imbalance of the load, by which the center of gravity of the load is brought under unchanged load orientation under the load receiving point, thus allowing a movement of the container within the guides in the ship, without these tilt by tilting.

Alternatively, if such balancing of the imbalance of the load is not possible, or if canting of the load is unproblematic, the skewing of the rope caused by the imbalance of the load when the load is lifted can also be compensated by movement of the crane. This can either manually via the crane operator z. B. based on a display or automatically.

The load on the crane structure when lifting the load may cause it to deform, causing the rope angle to change even without the load moving. Advantageously, therefore, according to the invention, when the load is lifted by determining a deviation of the cable angle from the vertical, the yield of the crane structure under the load is determined and / or the oblique position of the cable caused by the yielding of the crane structure is compensated by a movement of the crane. Here, the determination of the deviation or the compensation of this deviation in turn on the crane operator z. B. based on a display, or automatically.

Further advantageously, when a permissible value range for a deviation resulting from the measured cable angle is exceeded, in particular for the cable angle relative to the gravitational force direction and / or for the horizontal deviation of the load, the crane structure is protected by countermeasures. In particular, in this case the movement of the crane can be stopped in order to avoid overload.

In contrast, especially in the control of an off-shore crane, the countermeasures advantageously comprise at least partial release of the crane movements and / or of the rope in order, for. B. in a hooking of the lifting device with a ship, which moves away from the off-shore crane, to prevent overloading of the crane.

The countermeasures can either be initiated by the crane operator, which is advantageously warned by a warning function, or automatically by a corresponding automatic overload protection.

Further advantageously, the present invention comprises a crane, in particular a mobile harbor crane, a ship crane or an off-shore crane, which has a cable for lifting a load and is equipped with a crane control as described above. Likewise, the invention comprises corresponding boom and / or slewing cranes, as well as mobile cranes and crawler cranes. Obviously arise for such a crane the same, already described in the crane control advantages.

In addition to the previously described embodiment of the present invention with a sensor unit for determining a cable angle relative to the direction of gravity force, the present invention further comprises a crane control, which even without such a sensor unit in cranes, which have at least a first and a second cable harness for lifting the load, advantageous can be used.

The crane control according to the invention serves to control the interlockings of a crane, which has at least a first and a second cable strand for lifting a load, wherein the crane control has a load oscillation damping for damping spherical pendulum vibrations of the load. According to the invention, a first and a second sensor unit are now provided, which are assigned to the first and the second cable strand, in order to determine the respective cable angles and / or cable angular velocities of the first and second cable strands. Furthermore, the load oscillation damping has a control into which the cable angles and / or cable angular velocities determined by the first and the second sensor unit are received.

Compared to known arrangements, in which a sensor unit is attached to the hook of the crane or only on a rope, this results in numerous advantages: on the one hand results in a redundancy of this safety-critical element, so that in case of failure of a sensor unit, a measurement of the rope angle on the second sensor unit remains possible. Likewise, there is the possibility of detecting sensor errors. Furthermore, it is possible to achieve a noise reduction by subtracting the measured values, as well as by evaluation algorithms to implement a torsion compensation, that is, the consideration of a cable field rotation in the determination of the actual deflection angle of the load.

The controlled by the crane control signal boxes are advantageously the slewing gear for rotating the crane and / or the luffing mechanism for luffing the boom. By appropriate control of this control via the load oscillation damping so spherical vibrations of the load on the rope can be prevented.

Advantageously, the first and the second sensor unit each comprise a gyroscope unit. The gyroscopes measure the rope angular velocity, advantageously two gyroscopes are provided to measure the rope angular velocity in both the radial and tangential directions. Gyroscopes are particularly well suited for the requirements of the control of the load oscillation damping.

Further advantageously, the first and the second sensor unit of the present invention are each arranged in a cable follower element. The cable follower element follows the movement of that cable strand to which it is assigned. The sensor unit in turn measures the movement of the cable follower element, from which the movement of the cable strand can be determined. By Seilfolgeelemente results in a particularly accurate and reliable rope angle measurement.

Advantageously, the cable follower elements are each connected via a gimbal joint with the boom of the crane and follow the movement of the rope strand, which they are assigned. However, the connection of the cable follower elements via a gimbal joint advantageously serves only the mechanical connection and the guidance of the cable follower element, while the sensor units determine the movement of the cable follower elements via the gyroscope units according to the invention.

Advantageously, the data measured by the first and the second sensor unit are evaluated by a first and a second observer circuit. Such observer circuits are used to offset and interference, such. B. Seiloberschwingungen to suppress. The observer circuits serve to integrate the cable angular velocities measured by the gyroscopes and allow a reliable determination of the cable angles.

Further advantageously, according to the invention, a compensation of the data measured by the first and the second sensor unit takes place with respect to the installation angle of the sensor units and the angle of rotation of the crane. As a result, interference, which are caused by incorrect installation, be compensated software technology. If the sensitivity levels of the gyroscopes used are not exactly in the tangential and radial directions, but are tilted due to incorrect mounting, the sensors proportionally measure the rotational speed of the crane. This is taken into account by the compensation according to the invention.

Further advantageously, sensor errors are detected in the crane control according to the invention by comparing the data measured by the first and the second sensor unit. If one of the sensor units fails, the angular velocity is still detected by the other sensor unit. Thus, the basic function of the crane control can continue to be ensured. By subtraction of the angle signals of both sensor units in the respective directions can continue to detect a sensor error when a threshold value is exceeded. The crane can be brought to a safe condition immediately when a sensor fault occurs.

Further advantageously, the torsional vibration of the cable field is taken into account in the load oscillation damping by an averaging of the cable angles and / or cable angular velocities determined by the first and the second sensor unit. Such a cable field twist would affect the control used to dampen the spherical pendulum vibration of the load when using only one sensor unit. Now occurs in the inventive Crane control torsional vibration of the rope field, the sensor units on the two cable follower elements measure exactly an opposite parasitic oscillation both in the tangential and in the radial direction. By averaging the influence of this torsional vibration can, however, be eliminated according to the invention.

Furthermore advantageously, the load-deflection device according to the invention has a path planning module which predetermines the regulation of target trajectories. These desired trajectories specify the movements which the load is to carry out and are then used, in particular, when using an inverted model as as input variables of the control. The non-linear control results in a particularly simple implementation of the path planning module, since this only has to specify desired trajectories for the linear system of non-linear control and non-linear crane behavior. This makes it possible to achieve an extremely fast crane control with an outstanding response to the specifications entered by the crane operator by means of input elements.

Advantageously, the current system state of the crane, in particular the position of the jib and / or the cable angles and / or cable angular velocities determined by the first and second sensor units, enters the path planning module as an input variable. In particular, the position of the cantilever is important because z. B. depends on the maximum achievable radial velocity of this. Advantageously, the cable angles and / or cable angular velocities determined by the first and second sensor units also enter from input variables into the path planning module. This additional control loop thus enables a more accurate path planning taking into account the actual cable angle and / or the actual cable angular velocity.

Furthermore advantageously, in the path planning module according to the invention, restrictions of the system in the generation of the desired trajectories are taken into account. This prevents that calculated from the specifications of the crane operator guide variables, the manipulated variable limitations of the system such. B. violate the maximum speed. In particular, even if the current system state of the crane enters into the path planning module as an input variable, restrictions of the system that depend on this system state can also be taken into account. For example, the maximum possible radial speed depends on the position of the cantilever.

Further advantageously, the trajectory generation according to the invention is based on optimal control. According to the invention, such optimal control can be implemented particularly well in real time, since the nonlinear system according to the invention Regulation allows a particularly simple implementation of the path planning module.

Further advantageously, the path planning module according to the invention operates in the prediction within the time horizon with an increasing length of the calculation intervals. By such non-equidistant bases for the prediction, it is also possible to shorten the computing time considerably. In the near future, short intervals are chosen between the interpolation points, while larger intervals are selected for the distant future, so that overall a considerably reduced number of calculation steps results.

Furthermore advantageously, the position and the speed of the boom head is also involved in the regulation of the load oscillation damping. This results in the crane control according to the invention control loops both for the position and the speed of the boom head, as well as for the rope angle and / or rope angular velocity of the rope.

In a particularly advantageous embodiment, the system according to the invention with two sensor units has one or more of the features which have been described previously.

The present invention further comprises a crane for lifting a load, with interlocking mechanisms for moving the crane and the load and with a crane control for controlling the interlockings, wherein the crane control has a load sway loss for damping spherical pendulum vibrations of the load and wherein the crane at least two cable strands for lifting the load. According to the invention, two sensor units, which are assigned to the two cable strands, are provided in order to determine the respective cable angles and / or cable angular velocities. Furthermore, the load oscillation damping in this case has a control, in which enter the determined by the two sensor units rope angle and / or rope angular velocities. By such a crane, the same advantages as described above with respect to the crane control according to the invention result.

Furthermore, the crane according to the invention has a crane control, as described above.

Further advantageously, the crane according to the invention as interlockings while a slewing gear for rotating the crane and / or a luffing mechanism for luffing a boom, which are controlled by the crane control. By appropriate control of this control via the load oscillation damping so spherical vibrations of the load on the rope can be prevented.

The present invention further comprises a method for driving the interlocking of a crane, which has at least a first and a second cable string for lifting the load, wherein spherical pendulum vibrations of the load are damped by a load oscillation damping. According to the invention, the cable angles and / or cable angular velocities of the first and the second cable strand via a first and a second sensor unit, which are assigned to the first and the second cable strand, determined and go into the regulation of the load oscillation damping. By this method, the same advantages as described above in relation to the crane control result.

Advantageously, according to the invention, a compensation of the data measured by the first and the second sensor unit with respect to the installation angle of the sensor units and the rotation angle of the crane. As a result, deviations of the installation angle of the sensor units can be compensated by an exact radial or tangential alignment.

Further advantageously, sensor errors are detected by comparing the data measured by the first and second sensor units. It can be exploited by the inventive use of two sensor units, which are assigned to the respective cable strands, the redundancy gained thereby.

Furthermore advantageously, the torsional vibration of the cable field is taken into account in the load oscillation damping by an averaging of the cable angles and / or cable angular velocities determined by the first and the second sensor unit. So load swing damping can be taken into account that also torsional vibrations of the rope field occur, which influence the data of the sensor units.

Advantageously, the method according to the invention is carried out with a crane control, as described above.

Figur 0a:

ein Ausführungsbeispiel eines Hafenmobilkrans,

Figur 0b:

ein Ausführungsbeispiel eines Seilfolgeelements einer Kransteuerung,

Figuren 1a, 1b:

die Schwingung der Last, wenn das Seil vor dem Anheben der Last nicht lotrecht ausgerichtet wurde,

Figuren 2a - 2c:

ein Ausführungsbeispiel eines Verfahrens, bei welchem ein Ungleichgewicht der Last ausgeglichen wird,

Figuren 3a - 3c:

ein Ausführungsbeispiel eines Verfahrens, bei welchem das Nachgeben der Kranstruktur bei Belastung ausgeglichen wird,

Figur 4a:

ein Ausführungsbeispiel eines Off-Shore-Krans mit entsprechender Auslenkung des Seiles aus der Lotrechten durch eine Bewegung eines Schiffs und

Figur 4b:

die grafische Darstellung eines zulässigen Seilwinkelbereiches.

Figur 5:

ein Ausführungsbeispiel der vorliegenden Erfindung, bei welchem zwei Seilstränge mit jeweils zugeordneten Sensoreinheiten vorgesehen sind,

Figur 6:

eine Torsionsschwingung des Seilfeldes aus erstem und zweitem Seilstrang,

Figur 7:

ein Prinzipschaubild der bei einer Torsionsschwingung des Seilfeldes gemessenen Seilgeschwindigkeiten,

Figur 8:

eine Prinzipdarstellung des erfindungsgemäßen Kranes,

Figur 9:

eine Prinzipdarstellung des Wippwerkes des erfindungsgemäßen Kranes,

Figur 10:

eine Prinzipdarstellung der erfindungsgemäßen Kransteuerung,

Figur 11:

einen Vergleich der Vorgaben des Kranführers mit einer Soll-Trajektorie, welche von dem erfindungsgemäßen Bahnplanungsmodul generiert wird,

Figur 12a:

einen Vergleich einer Soll-Trajektorie mit der tatsächlichen Bewegung der Last bezüglich der Lastgeschwindigkeit,

Figur 12b:

einen Vergleich einer Soll-Trajektorie mit der tatsächlichen Bewegung der Last bezüglich der Lastposition,

Figur 13:

die Geschwindigkeit des Auslegerkopfes im Vergleich mit der Sollgeschwindigkeit der Last sowie dem durch die Bewegung entstehenden radialen Seilwinkel und

Figur 14:

die Zeit, welche zur Berechnung der Soll-Trajektorien benötigt wird.

The present invention will now be described in more detail with reference to embodiments and drawings. Showing:

Figure 0a:

an embodiment of a mobile harbor crane,

FIG. 0b:

an embodiment of a cable follower element of a crane control,

FIGS. 1a, 1b:

the vibration of the load, if the rope was not aligned vertically before lifting the load,

FIGS. 2a-2c:

an embodiment of a method in which an imbalance of the load is compensated,

FIGS. 3a-3c:

an embodiment of a method in which the yielding of the crane structure is balanced under load,

FIG. 4a

an embodiment of an off-shore crane with corresponding deflection of the rope from the vertical by a movement of a ship and

FIG. 4b:

the graphical representation of a permissible rope angle range.

FIG. 5:

An embodiment of the present invention, in which two cable strands are provided with respective associated sensor units,

FIG. 6:

a torsional vibration of the rope field of first and second strand of rope,

FIG. 7:

a schematic diagram of the measured during a torsional vibration of the rope field cable speeds,

FIG. 8:

a schematic diagram of the crane according to the invention,

FIG. 9:

a schematic diagram of the luffing mechanism of the crane according to the invention,

FIG. 10:

a schematic diagram of the crane control according to the invention,

FIG. 11:

a comparison of the specifications of the crane operator with a desired trajectory, which is generated by the path planning module according to the invention,

FIG. 12a:

a comparison of a desired trajectory with the actual movement of the load with respect to the load speed,

FIG. 12b:

a comparison of a desired trajectory with the actual movement of the load with respect to the load position,

FIG. 13:

the speed of the boom head in comparison with the target speed of the load and the resulting by the movement of the radial rope angle and

FIG. 14:

the time needed to calculate the desired trajectories.

In Figure 0a an embodiment of a jib crane according to the invention is shown, here a mobile harbor crane, as they are often used for handling cargo handling operations in ports. Such boom cranes can have load capacities of up to 140 t and a rope length of up to 80 m. The embodiment of the crane according to the invention in this case comprises a boom 1, which can be pivoted about a horizontal axis 2, with which it is hinged to the tower 3, up and down. The tower 3 can in turn be rotated about a vertical axis, whereby the boom 1 is rotated. The tower 3 is rotatably arranged for this purpose on an undercarriage 6, which is movable via wheels 7. To rotate the tower 3 not shown interlockings are present, for rocking the boom 1, the actuator 4. The rope 20 for lifting the load 10 is guided over a pulley on the boom head, wherein the Length of the rope 20 can be adjusted via winches. On the rope 20 a load receiving device is arranged at a load receiving point 25, for. As a manipulator or spreader over which the load 10 can be received. In the exemplary embodiment, the load receiving device additionally has a rotator device, via which the load 10 can be rotated on the load receiving device. In a further embodiment of the invention, the crane further comprises at least a first and a second cable strand for lifting the load, wherein all cable strands run from the jib tip to the load receiving device.

As shown in particular in the plan view, the load can be moved by rotating the tower 3 in the tangential direction and by rocking the boom 1 in the radial direction. In the vertical direction you load 10 is thereby moved by the luffing of the boom 1 and the change in the length of the cable 20. In addition, the load 10 can be rotated by the rotator unit on the load receiving device.

A first embodiment of the in Figure 0a shown mobile crane is now equipped with a crane control, which has a sensor unit for determining the cable angle relative to the direction of gravity force. In the exemplary embodiment, the sensor unit has two sensors, by means of which in each case the radial or the tangential cable angle relative to the direction of gravitational force can be determined. By this sensor unit, the orientation of the crane when lifting the load is considerably simplified, since the rope can be easily aligned in the vertical over the load 10 by this sensor unit.

However, the crane control according to the invention can be used not only in the illustrated embodiment, ie a mobile harbor crane, but also advantageously in other cranes, such as. As in ship cranes, off-shore cranes, truck cranes and crawler cranes.

The sensor unit for determining the cable angle relative to the direction of gravitational force is particularly advantageous in the case of jib cranes, since in these known systems, as they are known, for example. B. in cranes with a movable only in the horizontal direction trolley are used and which work on Meßkamerasysteme not be used. In the case of jib cranes, such measuring camera systems would in fact move together with the jib and thus only determine the angle of the rope with respect to the jib, but not with respect to the vertical. In addition, such systems would always have to be located directly behind the cable fix point on the boom head, which is hardly possible with a guided over a pulley on the boom head movable rope.

By contrast, the sensor unit for determining the cable angle relative to the direction of gravitational force can easily be mounted in a cable follower element 35, as shown in FIG FIG. 0b is shown, and directly determines the rope angle relative to the gravitational force direction in the tangential and radial directions. On a determination of the rope angle relative to the boom 1 can be completely dispensed with. However, if this angle of the rope relative to the boom 1 of interest, could also be arranged on the boom 1 another sensor unit for determining the angle of the boom relative to the gravitational force direction to the difference between the respective angle of rope and boom to the gravitational force direction, the angle between rope and to determine boom.

This in FIG. 0b shown rope follower element 35, on which the sensor unit is arranged for determining the cable angle relative to the direction of gravity, is attached to the boom head 30 of the boom 1 by gimbals 32 and 33 under the main pulley 31. The cable follower element 35 has rollers 36 through which the cable 20 is guided, so that the cable follower 35 follows the movements of the cable 20. The gimbals 32 and 33 allow the cable follower element to freely move about a horizontal and a vertical axis, but prevent rotational movements. The orientation of the cable follower element 35 and thus of the rope 20 relative to the direction of gravity force can thus be determined via the arranged on the cable follower 35 sensor unit for determining the rope angle relative to the direction of gravity force.

Further advantageously, in the exemplary embodiment, a gyroscope unit is additionally arranged on the cable follower element 35, via which the cable angular velocity in the radial and tangential direction can be measured, for which purpose at least two appropriately aligned gyroscopes are used. The data of the gyroscopes are advantageously a load oscillation damping available, which prevents the oscillation of the load during a movement of the crane.

If a plurality of cable strands is provided, via which the load-bearing element is suspended on the boom, corresponding cable follower elements 35 are advantageously assigned to at least two of these cable strands in order to be able to take into account the cable field twist resulting from a rotation of the load-bearing element from the cable-bed level. Advantageously, the cable follower elements are arranged on the cable strands arranged in each case outside, so that a cable field rotation is expressed maximally in the difference between the cable angles. The actual cable angle relative to the gravitational force direction, which corresponds to a deflection of the load from the vertical, can be determined by averaging the values from the sensor units at the respective cable follower elements, the rotation of the load from the difference of the values.

The universal joint 32 and 33 serves only the mechanical connection of the cable follower element 35 with the boom head 30, the measurement of the cable angle takes place solely via the sensor units integrated in the cable follower elements 35, but not by determining the angle between the cable follower element 35 and the boom 30. As a result, only the relative orientation of the rope with respect to the boom 30 could be determined, but not the rope angle of the rope 20 relative to the direction of gravity force.

In a further embodiment, wherein at least the first and the second cable strand, the load-receiving element is suspended on the boom, these are also associated with corresponding cable follower elements 35, which are equipped with gyroscope units and thus determine the rope speed of these cable strands. The determination of the cable speeds of the first and the second cable strand makes it possible to take into account the cable field distortion in the load swing damping for damping spherical pendulum oscillations of the load and to correct measuring errors. In this embodiment, the sensor units for determining the cable angle relative to the direction of gravitational force can also be dispensed with and the cable follower elements 35 can only be equipped with gyroscope units.

As an alternative to the arrangement of the sensor unit for determining the cable angle relative to the gravitational force direction on a cable follower element 35, this could also be z. B. are arranged on the cable receiving means, the cable follower elements, however, provide an improved possibility for determining the rotation of the load, especially in the case of several cable strands.

Since the load swing damping, which in DE 100 64 182 . DE 103 24 692 . DE 100 29 579 and DE 10 2006 033 277 are shown, and with which the crane control of the embodiment advantageously also equipped, go from a free hanging on the rope load and based on gyroscopic data, which are not suitable for the determination of absolute rope angle, these load pendulum systems only a commuting initially free and immovable on Prevent rope hanging load during movement of the crane.

In order to align the rope vertically before lifting the load or when lifting, so that the load can be lifted without swinging, the crane control according to the invention is now provided with the sensor unit according to the invention for determining a rope angle relative to the direction of gravity force.

FIG. 1 a shows the basic problem with a non-perpendicular orientation of the rope 20. The rope 20, which is already connected to the still-lying load 10 via a load-receiving means, points through the wrong orientation of the boom 1 while an angle φ _Sr relative to the direction of gravity shown in dashed lines. If the load 10 is now raised from this position by shortening the length of the rope 20, the results in FIG. 1b shown vibration around the perpendicular when the load 10 is released. Such vibration when lifting the load 10 is particularly dangerous because it is close to the ground and objects in the vicinity of the load 10 can be easily damaged.

In addition, the load 10, before it comes free, uncontrolled slip or twisted unevenly uncontrolled twisting. In FIGS. 1 a and 1 b is an example of the deflection φ _{Sr shown} in the radial direction. The same problem also arises for a deflection of the rope 20 in the tangential direction, which is caused by a faulty position of the tower 3.

In order to avoid such a deflection of the rope 20 from the vertical at the beginning of the stroke, the crane control therefore has a display which indicates the rope angle φ of the rope 20 relative to the gravitational force direction, that is to the vertical. The display can be z. B. on the one hand a vertical rope position optically and / or acoustically indicate and also indicate the direction in which the cable 20 is deflected by the perpendicular.

Such a display can thus z. B. display elements for a forward or rearward deflection and display elements for a deflection to the left or right, which indicate a deflection in the radial or in the tangential direction.

Alternatively, the horizontal deviation of the load from a zero position, which corresponds to a vertical orientation of the rope, can be displayed. In particular, in this case a graphical display of the zero position and the deviation of the load is conceivable, so that the crane operator, the absolute deflection of the load is displayed directly.

By such a display, the crane operator can easily align the crane at the beginning of the stroke so that the cable 20 is arranged vertically above the load 10. The correct vertical rope position can then z. B. be acoustically displayed by a beep.

In an alternative embodiment, a function for automatic alignment of the rope in the vertical direction is provided, optionally in addition to the display. By activating this function, the crane automatically aligns with the load after attaching the load handler so that the rope is in the vertical position. In order to avoid an uncontrolled movement of the crane in case of malfunction of the sensor unit, this automatic function is advantageously z. B. connected to a Seilkraftmeßeinrichtung, which switches off the automatic operation in case of errors.

When using a plurality of cable strands between the boom head and the load-carrying device, the cable field rotation can also be determined via a plurality of sensor units. This rope field twist corresponds to the rotation of the load-receiving means, for. As a spreader, and would lead to a rotation of the load when lifting the load. To prevent this, advantageously, in addition to the rope angle relative to the direction of gravitational force or the horizontal deviation of the load, also the rotation of the rope field is advantageously displayed. If the load receiving means has a rotor device, the cable field twist can hereby be set to 0 before the stroke, in order to prevent rotation of the load 10 during lifting. For this purpose, a function for automatic alignment of the rotor device may be advantageously provided in a further embodiment.

Furthermore, an embodiment of the crane control next to the display on a warning device, which the crane operator when exceeding permissible value range for a resulting from the measured rope angle deviation, in particular for the rope angle relative to the direction of gravity force, for the horizontal deviation of the load and / or the rope field rotation by an optical and / or acoustic signal warns. As a result, the crane operator has the ability to prevent excessive deflection of the rope and so the crane z. B. to protect against overload. Likewise, too much oscillation of the load when lifting can be avoided.

In an alternative embodiment, optionally in addition to the warning device, an automatic security device, e.g. be provided in the form of an overload protection, which automatically engages in the control of the crane when the permissible value range is exceeded. In particular, the automatic overload protection stops the movement of the crane in order to prevent overloading. The overload protection can be integrated into the load torque limit of the crane, which protects the crane against loading by a too large rope angle.

Furthermore, it is provided in a further embodiment that the lifting of the load 10 is not possible, as long as the rope angle or the Seilfeldverdrehung is not within the permissible range. As a result, an unwanted oscillation of the load 10 during lifting is effectively prevented.

In Figures 2 and 3 are now shown two situations in which the rope 20 is initially aligned vertically, but when lifting the load 10 is moved away from the vertical.

In FIGS. 2a to 2c This is done by the center of gravity 26 of the load 10 not being below the load receiving point 25 at the beginning of the lifting operation. Will the load 10 now, as in FIG. 2b shown, raised, this is inclined until the center of gravity 26 of the load is disposed below the load receiving point 25. By this tilting of the load 10 of the load receiving point 25 at which the rope 20 z. B. is attached to the load receiving means, but moved in the horizontal direction, in the case shown here in the radial direction inwards. As a result, the rope angle changes relative to the vertical, which in a complete Freeing the load 10 would lead to an undesirable vibration of the load.

Therefore, in one embodiment of the method during the lifting of the load 10, the deviation of the cable angle from the perpendicular is determined. In the simplest embodiment, the crane operator checks on the display the rope angle or the horizontal deviation and adjusts the crane during the stroke to compensate for the deviation of the rope angle from the vertical by the imbalance of the load again. In an improved embodiment, the imbalance of the load from the deviation of the rope angle from the vertical is determined and displayed, so that the crane operator can respond better.

In the in Figure 2c In the position shown, the crane has now been moved in such a way that the inclination due to the imbalance of the load, in which the center of gravity 26 is arranged below the load receiving point 25, has been compensated. Upon complete release of the load 10, an unwanted oscillation of the load due to the imbalance of the load is thereby avoided.

In an embodiment not shown, the load receiving means comprises a device for the particular linear movement of the load 10 relative to the load receiving point 25, via which the center of gravity 26 of the load can be arranged without tilting the load 10 below the load receiving point 25. For this purpose, the load handling device, z. B. a spreader, z. B. a longitudinal displacement of the load receiving point 25 relative to the load, for. As a container on.

If, when lifting the load, a deviation of the rope angle from the perpendicular is detected, the crane operator can move the load-bearing point relative to the load until the rope is again aligned vertically. Likewise, based on the deviation of the rope angle of the vertical, the imbalance of the load can be determined and displayed, so that the crane driver controlling the Longitudinal adjustment of the spreader can make use of this display. Likewise, an automatic adjustment of the spreader is conceivable.

Such an adjustment of the spreader on the basis of the deviation of the rope angle from the vertical is of particular advantage, since a tilting of the container, in particular when loading into a ship can lead to jamming of the container, through which the loading can be significantly impeded.

In FIGS. 3a to 3c Now, another effect can be seen, by which a deviation of the rope angle of the vertical can be caused when lifting the load. In FIG. 3a Before the start of the stroke, the rope 20 is still aligned vertically. Since the center of gravity 26 of the load is below the load receiving point 25, so the load has no imbalance, the load receiving point 25 does not move when lifting the load 10 in this case. As in FIG. 3b however, the crane structure yields by the load-lifting load, in which case the tower 3 and boom 1 are slightly bent forward. As a result, the boom tip 30, over which the cable 20 runs, is moved relative to the load receiving point 25, so that there is a deviation of the cable angle from the vertical by the yielding of the crane structure.

According to the invention, this deviation is compensated in a first embodiment of the method by the crane operator on the basis of the display of the rope angle when lifting the load. Likewise, the deviation of the rope angle from the perpendicular can be determined by the yielding of the crane structure under the load, which can then be displayed to facilitate the work of the crane operator. In a further embodiment, an automatic tracking of the crane for vertical alignment based on the data of the sensor unit for determining a cable angle relative to the direction of gravity force is possible. If the rope angle is again aligned in the vertical direction, the load can, as in Figure 3c shown to be lifted without vibration.

In FIG. 4a is another embodiment of the crane to see. This is an off-shore crane, which is arranged on an off-shore platform 50 and z. B. for loading a load 10 from a ship 60 on the platform 50 is used. Since the ship 60 can move relative to the platform 50, the rope angle of the rope 20 relative to the perpendicular can also be altered without movement of the crane by movement of the ship.

In order to take this situation into account, an overload function is provided in one exemplary embodiment of the crane control, which optionally can be used in addition to the warning and safety functions described above. To z. B. to prevent destruction of the crane, when the rope 20 hooked to the ship 60 and the movement of the ship threatens to overload the crane 60, countermeasures are initiated when the rope angle exceeds a maximum allowable range. In particular, in this case the movement of the crane can be partially released, z. B. by the rope 20 is released or the rotational movement of the tower 3. This release is carried out in a controlled manner with a certain counterforce to avoid sudden power surges.

In this way, based on the cable angle relative to the direction of gravity force, an overload protection that is simple to perform can be realized, which can only be realized with difficulty by means of a cable force sensor. By such an overload protection, which causes a partial release of the crane movement, also an uncontrolled grinding of the load 10 can be prevented via the ship 60.

The permissible range 70 for the cable angle in the X and Y direction is, for example, in FIG. 4b hatched shown. If the cable angle exceeds this permissible range 70, either the warning function or one of the overload functions is triggered.

FIG. 4b shows a display element for indicating a deviation from a vertical position of the rope, with an allowable range 70 for the rope angle or for the horizontal deviation in the X and Y direction, that is in the radial and tangential direction. The display of the rope angle is thereby graphically, for example by the rope angle in the in FIG. 4b shown diagram is shown as a dot. Instead of the rope angle and the horizontal deviation of the load from the zero position lying in the middle can be represented, that is, the distance of the load from the position in which it would be at the same crane position, but perpendicular rope. The crane driver can thus directly detect the absolute deflection of the load and thus estimate more easily how far the crane has to be moved for the correct alignment of the rope.

The determination according to the invention of the cable angle relative to the vertical by a sensor unit for determining a cable angle relative to the gravitational force direction and the corresponding crane controls and crane control method according to the invention, in addition to a simpler operation and alignment of the crane and a significantly increased safety when lifting loads possible.

In one embodiment of the present invention, the crane has at least a first and a second strand of rope connecting the load handling means to the boom tip. In particular, an improved damping of the spherical vibrations of the load is provided by the crane control according to the invention.

Control and automation concepts for cranes, which prevent the pendulum movement of the load on the rope during a crane movement, depend on the exact measurement of the rope angles. In particular, in the case of jib cranes, it is advantageous not to directly determine the rope angles via, for example, image processing methods, but to measure the angular velocities by means of gyroscopes.

However, since the gyroscope signals are offset and also detect disturbances such as rope harmonics, observer circuits are used to integrate the velocities to the cable angles.

To detect the angular velocities of the oscillating load, the gyroscopes are attached to the rope under the cantilever tip by means of a mechanical construction. Necessary for the detection of the spherical load vibration are two gyroscopes, which are arranged in the tangential and radial directions.

As in Figure 5 shown, is now proposed for improved load oscillation damping according to the invention, both the first and the second strand of rope a rope follower element, as in Fig. 0b shown is assigned. However, instead of the sensor unit for determining a cable angle relative to the direction of gravitational force, the cable follower elements are equipped with gyroscope units which are better suited for load-swing damping. About this an angular velocity detection of the oscillating crane load.

FIG. 0b shows a first cable follower element 35, on which in the embodiment shown here, the first cable strand associated with the first sensor unit is arranged. The first cable follower element is attached to the boom head 30 of the boom 1 by gimbal connections 32 and 33 under a first pulley 31, over which the first cable strand 20 is guided. The cable follower element 35 has rollers 36, through which the first cable strand 20 is guided, so that the cable follower 35 follows the movements of the cable strand 20. The gimbals 32 and 33 allow the cable follower element to freely move about a horizontal and a vertical axis, but prevent rotational movements. The radial and tangential angular velocity of the first cable follower element 35 and thus of the first cable strand 20 can thus be determined via the first sensor unit arranged on the cable follower element 35, which is designed as a gyroscope unit. A second cable follower element with a second sensor unit, which is assigned to a second cable strand, is constructed analogously to the first cable follower element and connected to the cantilever tip. The second cable follower element accordingly measures the angular velocity of the second cable strand.

The gyroscope signals (angular velocities in the tangential and radial directions) of both cable follower elements are processed and processed using identical algorithms. First of all, interference caused by incorrect installation is compensated by software (see equation 0.1). If the sensitivity levels of the gyroscope sensors are not tilted exactly in the tangential and radial directions, but tilted by incorrect assembly, the sensors measure the rotational speed of the crane proportionally. $${\dot{\phi }}_{t/\mathit{comp}}={\dot{\phi }}_{t/\mathit{r\; mess}}-\sin \left({\phi }_{\mathit{installation}}\right){\dot{\phi }}_D$$

The mounting or mounting angle for each gyroscopic sensor on both cable follower elements is φ _installed , φ̇ _D is the crane's rotational speed, φ̇ _{t / rmess} is the tangential or radial angular velocity, and φ̇ _{t / rkomp} is the resulting compensated gyroscope _signal .

Furthermore, the compensated measuring signals are integrated offset-free to the cable angles with an observer circuit. After this preparation, the rope angles are now available for both cable follower elements in tangential and radial directions.

The extension of the measurement concept by the second cable follower element leads to two significant advantages over the variant with only one cable follower element or the variant with the gyroscope sensors in the hook.

The first advantage is the redundancy of the load swing measurement. If a sensor fails on one of the two cable follower elements, the angular velocity is still detected by the sensor of the other mount. Thus, the basic function of the crane control (the pendulum damping and Trajektorienfolge) can be ensured. By subtraction of the angular signals of both cable follower elements in the respective directions can continue when a threshold value is exceeded detect a sensor error. Thus, the crane can be immediately brought to a safe condition when a sensor error occurs.

The second advantage is the possibility of compensating the torsional vibration of the load. In this case, as Equation 0.2 shows, the mean value of the angle signals of the two cable follower elements in the corresponding direction is calculated. $$\begin{array}{c}{\phi }_t=\frac{{\phi }_{\mathit{tbeobH}1}+{\phi }_{\mathit{tbeobH}2}}{2}\\ {\phi }_r=\frac{{\phi }_{\mathit{rbeobH}1}+{\phi }_{\mathit{rbeobH}2}}{2}\end{array}$$

The cable angle in the tangential direction φ _t is thus calculated from the mean value of the observed angle signals of the holder 41 φ _{tbeobH 1} and holder 42 φ _{tbeobH 2} . The same applies to the rope angle in the radial direction symbolized by the indices r . If a torsion of the load occurs with the angular velocity φ̇ _torsion , the gyroscopes on the cable follower elements 41 and 42 exactly measure an opposing disturbing oscillation in both the tangential and in the radial direction. Thus, the influence of the torsional vibration can be eliminated by averaging. The control of the load oscillation damping according to the invention, in which the data generated by the two gyroscope units are received, will now be described in more detail below.

In the case considered, the dynamics of boom movement is characterized by some predominant non-linear effects. The use of a linear controller would therefore cause large errors in trajectory tracking and inadequate damping of the load swing. To overcome these problems, the present invention utilizes a non-linear control approach based on the reversal of a simplified nonlinear model. This control procedure for the rocking movement of a jib crane allows a swing-free load movement in the radial direction. By using an additional stabilizing control loop, the resulting inventive Crane control a high accuracy Trajektoriennachführung and a good damping of load oscillation. Measurement results are presented to validate the good performance of the nonlinear trajectory tracking controller.

Jib cranes like the LIEBHERR Mobile Harbor Crane LHM (see Fig. 1 ) are used for the efficient handling of transshipment processes in ports. This type of jib crane is characterized by a load capacity of up to 140 tons, a maximum reach of 48 meters and a rope length of up to 80 meters. During the conversion process, a spherical load oscillation is excited. This load oscillation must be avoided for safety and performance reasons.

As in Fig. 1 shown there is such a mobile harbor crane from a mobile platform 6, to which a tower 3 is attached. The tower 3 can be rotated about a vertical axis, its position being described by the angle φ _D. On the tower 3, a boom 1 is pivotally mounted, which can be tilted by the actuator 4, wherein its position is described by the angle φ _A. The load 10 is suspended on a rope of length l _s from the head of the boom 1 and can oscillate at the angle φ _Sr.

In general, cranes are under-actuated systems that exhibit vibration behavior. Therefore, many unregulated and controlled control solutions have been proposed in the literature. However, these approaches are based on the linearized dynamic model of the crane. Most of these contributions do not consider the actuator dynamics and kinematics. In a jib crane powered by hydraulic actuators, the dynamics and kinematics of the hydraulic actuators are not negligible. In particular, in the boom actuator (hydraulic cylinder), the kinematics must be considered.

The following embodiment of the present invention utilizes a flatness-based control approach for the radial direction of a boom crane. The approach is based on a simplified nonlinear model of the crane. Thus, the law of linearizing control can be formulated. Furthermore, it is shown that the zero dynamics of the non-simplified non-linear control loop guarantees a sufficient damping characteristic.

1. NONLINEAR MODEL OF CRANE

• Vernachlässigen der Masse und der Elastizität des Seils
• Annahme, dass Last eine Punktmasse ist
• Vernachlässigen der Zentripetal- und Coriolis-Terme

Considering the control objectives of preventing the load swing and tracking a reference trajectory in the radial direction, the non-linear dynamic model for the seesaw motion must be derived. The first part of the model is obtained by

• Neglecting the mass and the elasticity of the rope
• Assume that load is a point mass
• Neglecting the centripetal and Coriolis terms

Using the Newton / Euler method and taking into account the given assumptions leads to the following differential equation of the motion for the load oscillation in the radial direction: $${\ddot{\phi }}_{\mathit{Sr}}+\frac{G}{l_S}\sin \left({\phi }_{\mathit{Sr}}\right)=\frac{\cos \left({\phi }_{\mathit{Sr}}\right)}{l_S}{\ddot{r}}_A$$

Fig. 8 shows a schematic representation of the rocking motion, where φ _Sr, the radial rope angle, φ̈ _Sr, the radial angular acceleration, l _{S is} the cable length, r̈ _{A is} the acceleration of the boom end and g is the gravitational constant.

The second part of the dynamic model describes the kinematics and dynamics of the actuator for the radial direction. Assuming that the hydraulic cylinder has first order behavior, the differential equation of motion is obtained as follows: $${\ddot{z}}_{\mathit{cyl}}=-\frac{1}{T_W}{\dot{z}}_{\mathit{cyl}}+\frac{K_{\mathit{VW}}}{T_W{A}_{\mathit{cyl}}}{u}_l$$

Where z̈ _zyl and _{żzyl are} the cylinder _acceleration and velocity, T _{W is} the time constant, A _{zyl is} the cross-sectional area of the cylinder, u _{W is} the input voltage of the servo valve, and K _{VW is} the proportional constant of flow rate to u _W.

differenziert. $$\begin{array}{l}{\dot{r}}_A=-l_A\sin \left({\phi }_A\right)K_{\mathit{Wz}1}\left({\phi }_A\right){\dot{z}}_{\mathit{zyl}}\\ {\ddot{r}}_A=-l_A\sin \left({\phi }_A\right)K_{\mathit{Wz}1}\left({\phi }_A\right){\ddot{z}}_{\mathit{zyl}}-K_{\mathit{Wz}3}\left({\phi }_A\right){\dot{z}}_{\mathit{zyl}}^2\end{array}$$

k _Wz1 und k _Wz3 beschreiben die Abhängigkeit von den geometrischen Konstanten d_a ,d_b ,α ₁,α ₂ und dem Wippwinkel ϕ_A . (siehe Figur 9) l_A ist die Länge des Auslegers. Fig. 9 shows a schematic representation of the kinematics of the actuator with the geometric constants d _a , d _b , α ₁ , α ₂ . To obtain a conversion of cylindrical _coordinates ( z _zyl ) to _{Ausladungskoordinaten} ( r _A ), the kinematic equation $$r_A\left(z_{\mathit{cyl}}\right)=l_A\cos \left({\alpha }_{A0}-\arccos \left(\frac{d_a^2+d_b^2-{\mathrm{<figure-callout\; id="2"\; label="z\; cyl"\; filenames="imgf0008.png,imgf0015.png"\; state="\{\{state\}\}">z\; </figure-callout>}}_{\mathit{cyl}}^{\mathit{}}}{2d_a{d}_b}\right)\right)$$

differentiated. $$\begin{array}{l}{\dot{r}}_A=-l_A\sin \left({\phi }_A\right)K_{\mathit{wz}1}\left({\phi }_A\right){\dot{z}}_{\mathit{cyl}}\\ {\ddot{r}}_A=-l_A\sin \left({\phi }_A\right)K_{\mathit{wz}1}\left({\phi }_A\right){\ddot{z}}_{\mathit{cyl}}-K_{\mathit{wz}3}\left({\phi }_A\right){\dot{z}}_{\mathit{<figure-callout\; id="2"\; label="cyl"\; filenames="imgf0008.png,imgf0015.png"\; state="\{\{state\}\}">cyl</figure-callout>}}^2\end{array}$$

k _{Wz 1} and k _{Wz 3} describe the dependence on the geometric constants d _a , d _b , α ₁ , α ₂ and the rocking angle φ _A. (please refer FIG. 9 ) l _A is the length of the boom.

Formulating the first-order behavior of the actuator in Ausladungskoordinaten by using the equations (4) leads to a non-linear differential equation. $${\ddot{r}}_A=-\frac{K_{\mathit{wz}3}}{\underset{a}{\underset{\}}{{\mathrm{<figure-callout\; id="2"\; label="l\; A"\; filenames="imgf0008.png,imgf0015.png"\; state="\{\{state\}\}">l\; </figure-callout>}}_A^{}{\mathrm{<figure-callout\; id="2"\; label="sin"\; filenames="imgf0008.png,imgf0015.png"\; state="\{\{state\}\}">sin</figure-callout>}}^2\left({\phi }_A\right)K_{\mathit{wz}1}^2}}}{\dot{r}}_A^2-\frac{1}{\underset{b}{\underset{\}}{T_W}}}{\dot{r}}_A-\frac{K_{\mathit{VW}}{l}_A\sin \left({\phi }_A\right)K_{\mathit{wz}1}}{\underset{m}{\underset{\}}{T_W{A}_{\mathit{cyl}}}}}{u}_l$$

werden die Gleichungen (1) und (6) verwendet. Hierdurch führen der als Eingabe verwendete Zustand x = [r_A ṙ_A ϕ_Sr ϕ̇_Sr ] ^T und die als Ausgabe vorgesehene radiale Position der Last y = r_LA zu: $$\begin{array}{l}{\underline{f}}_l\left({\underline{x}}_l\right)=\left[\begin{array}{c}{x}_{l,2}\\ -a{x}_{l,2}^2-b{x}_{l,2}\\ x_{l,4}\\ -\frac{g}{l_S}\sin \left(x_{l,3}\right)+\frac{\cos \left(x_{l,3}\right)}{l_S}\left(a{x}_{l,2}^2+b{x}_{l,2}\right)\end{array}\right]:{\underline{g}}_l\left({\underline{x}}_l\right)=\left[\begin{array}{c}0\\ -m\\ 0\\ \frac{\cos \left(x_{l,3}\right)m}{l_S}\end{array}\right]\\ h_l=\left(x_l\right)=x_{l,1}+l_S\sin \left(x_{l,3}\right)\end{array}$$

To represent the nonlinear model in the form $$\begin{array}{l}{\underset{}{\dot{x}}}_l={\underset{}{f}}_l\left({\underset{}{x}}_l\right)+{\underset{}{G}}_l\left({\underset{}{x}}_l\right)\cdot u_l\\ y_l=H_l\left({\underset{}{x}}_l\right)\end{array}$$

the equations (1) and (6) are used. As a result, the state used as input x = [ r _A ṙ _A φ _Sr φ̇ _Sr ] ^T and the radial position of the load y = r _LA provided as output to: $$\begin{array}{l}{\underset{}{f}}_l\left({\underset{}{x}}_l\right)=\left[\begin{array}{c}{x}_{l.2}\\ -a{x}_{l.2}^2-b{x}_{l.2}\\ x_{l.4}\\ -\frac{G}{l_S}\sin \left(x_{l.3}\right)+\frac{\cos \left(x_{l.3}\right)}{l_S}\left(a{x}_{l.2}^2+b{x}_{l.2}\right)\end{array}\right]:{\underset{}{G}}_l\left({\underset{}{x}}_l\right)=\left[\begin{array}{c}0\\ -\mathrm{<figure-callout\; id="0"\; label="m"\; filenames="imgf0014.png,imgf0015.png"\; state="\{\{state\}\}">m</figure-callout>}\\ 0\\ \frac{\cos \left(x_{l.3}\right)m}{l_S}\end{array}\right]\\ H_l=\left(x_l\right)=x_{l.1}+l_S\sin \left(x_{l.3}\right)\end{array}$$

2. Non-linear control approach

The following considerations are made on the assumption that the right side of the differential equation for the load swing can be linearized. Thus, the excitation of the radial load oscillation is decoupled from the radial rope angle φ _Sr. $${\ddot{\phi }}_{\mathit{Sr}}+\frac{G}{l_S}\sin \left({\phi }_{\mathit{Sr}}\right)=\frac{1}{l_S}{\ddot{r}}_A$$

To find a flat output for the simplified non-linear system, the relative degree must be determined.

2.1 Relative degree

The relative degree is defined by the following conditions: $$\begin{array}{ll}{L}_{{\underset{}{G}}_l}{L}_{{\underset{}{f}}_l}^i{H}_l\left({\underset{}{x}}_l\right)=0& \forall i=0....r-2\\ L_{{\underset{}{G}}_l}{L}_{{\underset{}{f}}_l}^{r-1}{H}_l\left({\underset{}{x}}_l\right)\ne 0& \forall x\in R^n\end{array}$$

stellt die Lie-Ableitung entlang des Vektorfelds f _l bzw. $L_{{\underline{g}}_l}$

entlang des Vektorfelds g_l dar. Mit der realen Ausgabe $$y_l^{*}=h_l^{*}\left({\underline{x}}_l\right)=x_{l,1}+l_S{x}_{l,3}$$

wird ein relativer Grad von r = 2 erhalten. Da die Ordnung des vereinfachten nichtlinearen Modells 4 ist, ist y_l eine nicht flache Ausgabe. Doch mit einer neuen Ausgabe $$y^{*}=h^{*}\left(\underline{x}\right)=x_1+l_S{x}_3$$

wird ein relativer Grad von r = 4 erhalten. Angenommen, dass nur kleine radiale Seilwinkel eintreten, kann die Differenz zwischen der realen Ausgabe y_l und der flachen Ausgabe $y_l^{*}$

vernachlässigt werden. Diese Vereinfachung wird gewählt, um die Rechenzeit für die in Kapitel 3 beschriebene Trajektoriengenerierung so gering wie möglich zu halten.The operator $L_{{\underset{}{f}}_l}$

represents the Lie derivative along the vector field f _l or $L_{{\underset{}{G}}_l}$

along the vector field g _l . With the real output $$y_l^{*}=H_l^{*}\left({\underset{}{x}}_l\right)=x_{l.1}+l_S{x}_{l.3}$$

a relative degree of r = 2 is obtained. Since the order of the simplified nonlinear model is 4, y _{l is} a non-flat output. But with a new edition $$y^{*}=H^{*}\left(\underset{}{x}\right)=x_1+l_S{x}_3$$

a relative degree of r = 4 is obtained. Assuming that only small radial rope angles occur, the difference between the real output y _l and the flat output can be $y_l^{*}$

be ignored. This simplification is chosen to minimize the computation time for the trajectory generation described in Chapter 3.

2.2 Exact Linearization

und das linearisierende Steuersignal u_l wird berechnet durch $$\begin{array}{cc}{u}_l& =\frac{-L_{{\underline{f}}_l}^r{h}_l^{*}\left({\underline{x}}_l\right)+v_l}{L_{{\underline{x}}_l}{L}_{{\underline{f}}_l}^{r-1}{h}_l^{*}\left({\underline{x}}_l\right)};v_l\dots \mathrm{new\; input}\hfill \\ & =\frac{g\sin \left(x_{l,3}\right)x_{l,4}^2-g\cos \left(x_{l,3}\right)\left(-\frac{g}{l_S}\sin \left(x_{l,3}\right)+\frac{a}{l_S}{x}_{l,2}^2+\frac{b}{l_S}{x}_{l,2}\right)+v_l}{\frac{\mathit{gm}}{l_S}\cos \left(x_{l,3}\right)}\hfill \end{array}$$

Since the simplified system representation is differentially flat, an exact linearization can be made. Therefore, a new input is defined as $v={\stackrel{\mathrm{....}}{y}}_l^{*}$

and the linearizing control signal u _l is calculated by $$\begin{array}{cc}{u}_l& =\frac{-L_{{\underset{}{f}}_l}^r{H}_l^{*}\left({\underset{}{x}}_l\right)+v_l}{L_{{\underset{}{x}}_l}{L}_{{\underset{}{f}}_l}^{r-1}{H}_l^{*}\left({\underset{}{x}}_l\right)};v_l...\mathrm{new\; input}\hfill \\ & =\frac{G\sin \left(x_{l.3}\right)x_{l.4}^2-G\cos \left(x_{l.3}\right)\left(-\frac{G}{l_S}\sin \left(x_{l.3}\right)+\frac{a}{l_S}{x}_{l.2}^2+\frac{b}{l_S}{x}_{l.2}\right)+v_l}{\frac{\mathit{gm}}{l_S}\cos \left(x_{l.3}\right)}\hfill \end{array}$$

In order to stabilize the resulting linearized system, error feedback is derived between the reference trajectory and the derivatives of the output y *. $$u_l=\frac{-L_{{\underset{}{f}}_l}^r{H}_l^{*}\left({\underset{}{x}}_l\right)+v_l-{\displaystyle \underset{i=0}{\overset{r-1}{\Sigma }}{k}_{l.i}}\left[L_{{\underset{}{f}}_l}^i{H}_l^{*}\left({\underset{}{x}}_l\right)-y_{l.\mathit{ref}}^{\underset{*}{\left(i\right)}}\right]}{L_{{\underset{}{G}}_l}{L}_{{\underset{}{f}}_l}^{r-1}{H}_l^{*}\left({\underset{}{x}}_l\right)}$$

The feedback gains k _{l, i} are obtained by the pole placing technique. FIG. 10 shows the resulting structure of the linearized and stabilized system.

verwendet. Die resultierende interne Dynamik ist dabei in der noch nicht veröffentlichten DE 10 2006 048 988 gezeigt, deren Inhalt einen Bestandteil der vorliegenden Anmeldung darstellt.The tracking control unit is based on the simplified load oscillation ODE (8) and not on the load oscillation ODE (1). Further, for the controller design, the fictitious output $y_l^{*}$

used. The resulting internal dynamics is in the yet unpublished DE 10 2006 048 988 shown, the content of which forms part of the present application.

3. Path planning / trajectory generation A. Formulation of the optimal control problem

The problem of trajectory generation is formulated as a limited open-chain optimal control problem for the linearized state feedback system. Due to the relevant calculation time for the solution of the optimal control problem, the model predictive trajectory generation is performed with a non-negligible sampling time. Also, a discretization of the time axis is introduced by the numerical solution method itself. For the sake of simplicity, however, the optimal control problem is continuously represented in continuous time.

The model equations are given by: $$\begin{array}{l}{\dot{x}}_{\mathit{lin}}=A_{\mathit{lin}}{x}_{\mathit{lin}}+b_{\mathit{lin}}{u}_{\mathit{lin}}.{\mathrm{<figure-callout\; id="0"\; label="x\; lin\; t"\; filenames="imgf0014.png,imgf0015.png"\; state="\{\{state\}\}">x\; </figure-callout>}}_{\mathit{lin}}\left(t_{}\right)\left({}_0\right)=x_{\mathit{lin}.0}\\ {\mathit{y}}_{\mathit{lin}}={\mathit{C}}_{\mathit{lin}}{\mathit{x}}_{\mathit{lin}}\end{array}$$

The state variables x _lin are the states of the integrator chain resulting from the linearized system consisting of flatness-based controller (equation (14)) and nonlinear system (equation (6)) and the states of the integrator chain for the reference trajectory. Additional states are introduced to get a smooth input v . The initial state x _{lin. 0} is derived from the states of these integrators, the current system output and its derivatives. The outputs y _{lin of} the linear system (Equation (15)) are variables corresponding to the shallow output y ^* (Equation (12)) and its first and second derivatives. These variables are the position, velocity and acceleration of the load in the radial direction.

berücksichtigt zum einen die quadratische Abweichung der prognostizierten Ausgänge y_lin von deren Referenzprognose w(t) und zum anderen die quadratische Änderung der Eingangsgröße u_lin . Der Optimierungshorizont t_f - t ₀, die symmetrische, positiv semi-definite Wichtungsmatrix Q und der Wichtungskoeffizient r > 0 sind wesentliche Einstellungsparameter für die Modellprädiktive Trajektoriengenerierung.The quality functional $$J_c=\frac{1}{2}\underset{t_0}{\overset{t_f}{\int }}\left({\left(y_{\mathit{lin}}-w\right)}^{T}Q\left(y_{\mathit{lin}}-w\right)+r{\dot{\mathit{u}}}_{\mathit{<figure-callout\; id="2"\; label="lin"\; filenames="imgf0008.png,imgf0015.png"\; state="\{\{state\}\}">lin</figure-callout>}}^2\right)\mathit{dt}$$

considers on the one hand the quadratic deviation of the predicted outputs y _lin from their reference prediction w ( t ) and on the other hand the quadratic change of the input _quantity u _lin . The optimization horizon t _f - t ₀ , the symmetric, positive semi-definite weighting matrix Q and the weighting coefficient r > 0 are essential setting parameters for the model predictive trajectory generation.

The optimization horizon t _f - t ₀ should capture the essential dynamic behavior of the process / system. This is defined by the period of load swinging (up to 18 seconds for the crane under consideration). Experiments show that 10 seconds are sufficient for the optimization horizon.

The reference prognosis w ( t ) for the load position, speed and acceleration is generated from the hand lever signals of the crane operator (set speeds). The prediction takes into account speed reductions as the load approaches the limits of the work area.

The model predictive trajectory generation considers restrictions on the process variables as limitations of the optimal control problem. $$\begin{array}{l}{u}_{\mathit{lin}.\min }\le u_{\mathit{lin}}\le u_{\mathit{lin}.\mathrm{Max}}\\ y_{\mathit{lin}.\min }\le y_{\mathit{lin}}\le y_{\mathit{lin}.\mathrm{Max}}\end{array}$$

Restrictions on the input change are used to avoid high-frequency excitations of the system. $${\dot{u}}_{\mathit{lin}.\min }\le {\dot{u}}_{\mathit{lin}}\le {\dot{u}}_{\mathit{lin}.\mathrm{Max}}$$

Thus, the rates of change u̇ _lin must be considered as manipulated variables in the formulation of the optimal control problem .

The generation of the reference trajectories leads to an external control loop ( Figure (10 )). Thus, the results of the stability considerations of model predictive regulations are applicable. Conditions for the guaranteed stability of the closed loop under nominal conditions normally require stabilizing limitations of the states at the end of the optimization horizon together with a suitable evaluation of the final state. For a "zero-state terminal constraint" one would have to introduce fixed end values, which depend on the stationary states in connection with the reference inputs, for the states which are not to be integrated. $$x_{\mathit{lin}}\left(t_f\right)=x_{\mathit{lin}.f}\left(w\left(t_f\right)\right)$$

Limitations of this type (Equation (19)) are likely to cause unsolvable optimal control problems under non-nominal conditions, such as model uncertainties or measurement noise, especially for short optimization horizons. Thus, the equation constraint (19) becomes a quadratic penalty term with symmetric, positive definite weighting matrix Q approximates what extends the original quality function as follows: $$J=J_c+\frac{1}{2}{\left(x_{\mathit{lin}}\left(t_f\right)-x_{\mathit{lin}.f}\right)}^T\tilde{Q}\left(x_{\mathit{lin}}\left(t_f\right)-x_{\mathit{lin}.f}\right)$$

B. Numerical solution of the optimal control problem

The continuous time, constrained, linear-quadratic optimal control problem (15) - (20) is discretized. $$\begin{array}{l}{\mathrm{<figure-callout\; id="0"\; label="t"\; filenames="imgf0014.png,imgf0015.png"\; state="\{\{state\}\}">t</figure-callout>}}_0={\mathrm{<figure-callout\; id="0"\; label="t"\; filenames="imgf0014.png,imgf0015.png"\; state="\{\{state\}\}">t</figure-callout>}}^0\le {\mathrm{<figure-callout\; id="1"\; label="t"\; filenames="imgf0007.png,imgf0008.png"\; state="\{\{state\}\}">t</figure-callout>}}^1\le ...\le t^K=t_f\\ x_{\mathit{lin}}^{k+1}=A^k{x}_{\mathit{lin}}^k+b^k{u}_{\mathit{lin}}^k.{}_{}k=0.....K-1\\ {\mathrm{<figure-callout\; id="0"\; label="x\; lin"\; filenames="imgf0014.png,imgf0015.png"\; state="\{\{state\}\}">x\; </figure-callout>}}_{\mathit{lin}}^{\mathit{}}=x_{\mathit{lin}.0}\\ y_{\mathit{lin}}^k=C_{\mathit{lin}}^k{x}_{\mathit{lin}}^k.{}_{}k=0.....K\end{array}$$

u^k and $y_{\mathit{lin}}^k$

die Werte der entsprechenden Variablen in den Diskretisierungpunkten t^k bezeichnen. Die Matrizen und Vektoren A^k, b^k and C^k erhält man durch Lösen der Transitionsgleichung in [t^k ,t ^k+1] aus A, b und C.In which $x_{\mathit{lin}}^k.$

u ^k and $y_{\mathit{lin}}^k$

denote the values of the corresponding variables in the discretization points t ^k . The matrices and vectors A ^k , b ^k and C ^k are obtained by solving the transition equation in [ t ^k , t ^{k +1} ] from A, b and C.

The quality functional (Equation (20)) and the constraints (Equations (17) (18)) are also correspondingly discretized.

des diskreten Problems approximiert und kann mit einem üblichen "Interior Point" Algorithmus gelöst werden. In dem Algorithmus wird die Struktur der diskreten Modellgleichungen in einem RICCATI-ähnlichen Ansatz genutzt, um eine Lösung der NEWTONschritt-Gleichung mit O(K(m ³ + n ³)) Operationen zu erhalten. D.h. der Berechnungsaufwand steigt linear mit dem Optimierungshorizont K und kubisch mit der Anzahl der Stellgrößen(m) und Zustandsvariablen(n).Thus, the continuous-time optimal control problem becomes a task of quadratic programming for the state variables and manipulated variables $\left[x_{\mathit{lin}}^k{u}_{\mathit{lin}}^k\right]$

The discrete problem approximates and can be solved with a standard "Interior Point" algorithm. The algorithm uses the structure of discrete model equations in a RICCATI-like approach to provide a solution to the problem NEWTON step equation with O ( K ( m ³ + n ³ )) to obtain operations. That is, the computational effort increases linearly with the optimization horizon K and cubic with the number of manipulated variables ( m ) and state variables ( n ).

Not equidistant discretization Δ t ^k = t ^{k + 1} - t ^k in the prediction horizon of the MPC's help the dimension of the optimal control problem to be limited. The illustration shows that the initial step size is determined by the timing of the trajectory generation and then increases linearly within the prediction horizon.

By the crane control according to the invention with the corresponding load oscillation damping, in which receive data from the two sensor units associated with the respective cable strands and which is constructed as described above, a fast and safe damping of the spherical pendulum vibrations of the load can be achieved with only minimal pendulum swings. This is shown by the following measurement results, which were carried out with a rope length of 57 m and a load of 3.5 t.

FIG. 11 shows the speed of the load, once as it is specified by the crane operator by means of an input element, and once as it is specified via the inventive path planning module by means of optimal control as a target trajectory. Here, the limitations of the system are taken into account, so that the upper limit for the speed of the load depends on the radial load position, since the geometry of the boom and the luffing cylinder allow different maximum speeds at different boom positions. For the maximum acceleration, however, a constant restriction is given.

FIG. 12a now compares this desired trajectory with the measured speed of the load. The regulation according to the invention follows the desired trajectory, the path planning module compensating for uncertainties in the model by model-based path planning. This results in a fast and subdued movement the load without significant overshoots. FIG. 12b then shows the corresponding trajectory of the load position.

The control according to the invention damps the spherical oscillations of the load by corresponding compensating movements of the boom during and at the end of each maneuver. This is in FIG. 13 shown, from which the counter-movements carried out by the cantilever tip arise, which counteract the vibration of the load. This allows the rope angle to be limited to less than 3 °.

The computing time required for the online calculation of the optimal solution problem in the path planning module is in FIG. 14 shown. This results in computing times between 54 msec and 66 msec. Decisive for this extremely short response of the path planning to specifications of the crane operator is on the one hand the fast solvability by the downstream linear distance of non-linear control and non-linear crane system, and within the prediction horizon increasing length of the intervals between the bases of the prediction.

Claims (14)

1. A crane control for driving the positioners of a crane which includes at least one first and one second strand of cables for lifting the load (10) comprising a load oscillation damping for damping spherical pendular oscillations of the load (10), wherein first and second sensor units are provided which are associated to the first and second strands of cables in order to determine the respective cable angles and/or cable angular velocities,
   characterized in that
   the load oscillation damping includes a non-linear control in which the cable angles and/or cable angular velocities determined by the first and second sensor units are considered, and wherein the non-linear control is based on the inversion of a non-linear physical model of the movement of the load (10) in dependence on the movements of the positioners, wherein due to the inversion the movement of load serves as an input variable to drive the positioners.
2. The crane control according to claim 1, wherein the first and second sensor units each comprise a gyroscope unit.
3. The crane control according to claim 1 or 2, wherein the first and second sensor units are each arranged in a cable follower (41, 42), with the cable followers (41, 42) preferably each being connected with the boom (1) of the crane via a cardan joint and following the movement of the strand of cables to which they are associated
4. The crane control according to any of the preceding claims, wherein the data measured by the first and second sensor units are evaluated by first and second observer circuits, wherein a compensation of the data measured by the first and second sensor units is preferably effected with respect to the mounting angle of the sensor units and the slewing angle of the crane and wherein sensor errors are detected particularly preferably by a comparison of the data measured by the first and second sensor units.
5. The crane control according to any of the preceding claims, wherein the torsional oscillation of the cable field is considered in the load oscillation damping by forming an average from the cable angles and/or cable angular velocities determined by the first and second sensor units.
6. The crane control according to any of the preceding claims, wherein the load oscillation damping comprises a path planning module, which specifies desired trajectories for the control, wherein the current system status of the crane, in particular the position of the boom (1) and/or the cable angles and/or cable angular velocities determined by the first and second sensor units, is preferably included in the path planning module as input variables, wherein the path planning module particularly preferably considers restrictions of the system when generating desired trajectories and wherein, particularly advantageously, the path planning module comprises an optimal control for generating the desired trajectories, and wherein, still preferably, the path planning module employs an increasing length of the calculation intervals for the prediction within the time horizon.
7. The crane control according to any of the preceding claims, wherein the position and the velocity of the boom head (30) are considered in the control of the load oscillation damping.
8. A crane for lifting a load (10), comprising positioners for moving the crane and a load (10), wherein the crane includes at least two strands of cables for lifting the load (10) and wherein two sensor units are provided which are associated to the two strands of cables in order to determine the respective cable angles and/or cable angular velocities, wherein the crane comprises a crane control for driving the positioners according to any of claims 1 to 7.
9. The crane according to claim 8, preferably comprising a slewing gear for slewing the crane and/or a luffing gear for luffing up a boom (1), which are driven by the crane control.
10. A method for driving the positioners of a crane which includes at least one first and one second strand of cables for lifting the load (10), wherein spherical pendular oscillations of the load (10) are damped by a load oscillation damping, wherein the cable angles and/or cable angular velocities of the first and second strands of cables are determined via first and second sensor units which are associated to the first and second strands of cables,
    characterized in that
    the load oscillation damping includes a non-linear control in which the cable angles and/or cable angular velocities determined by the first and second sensor units are considered, and wherein the non-linear control is based on the inversion of a non-linear physical model of the movement of the load (10) in dependence on the movements of the positioners, wherein, due to the inversion, the movement of the load serves as an input variable to drive the positioners.
11. The method according to claim 10, wherein a compensation of the data measured by the first and second sensor units is effected with respect to the mounting angle of the sensor units and the slewing angle of the crane.
12. The method according to claim 9 or 10, wherein sensor errors are detected by a comparison of the data measured by the first and second sensor units.
13. The method according to any of the claims 10 to 12, wherein the torsional oscillation of the cable field is considered in the load oscillation damping by forming an average from the cable angles and/or cable angular velocities determined by the first and second sensor units.
14. The method according to any of the claims 10 to 13 with a crane control according to any of claims 1 to 7.

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