METHOD FOR CONTROLLING THE MOVEMENT OF A LOAD IN A WORKSPACE OF A TRAFFIC TRANSPORTATION EQUIPMENT

Description

[0001] The present invention relates to a method for controlling the movement of a load in a working space of a load transport device by means of a control device of the load transport device, wherein the load transport device comprises a load carrier and at least one load receiving device attached to the load carrier for receiving the load, and at least three positioning cables and at least three suspension devices arranged at a distance from one another, wherein each suspension device has at least one positioning cable winch for winding and unwinding one of the positioning cables, and wherein the load carrier is suspended from the suspension devices by means of the positioning cables, wherein the load carrier and the load receiving device attached thereto are movable in and / or above the working space by actuating the positioning cable winches, wherein the method comprises the steps: Determining the target coordinates of a point in the workspace towards which the load-handling device is to be moved; determining a load measurement by measuring the weight of the load held by the load-handling device using a load measuring device of the load transport device; determining the actual cable lengths of the positioning cables; determining the target cable lengths of the positioning cables to be set by the respective positioning cable winch by winding or unwinding for the target coordinates of the point and the current load measurement; adjusting the actual cable lengths of the respective positioning cables to the target cable lengths of the respective positioning cables by controlling the respective positioning cable winch by means of a cable length control of the control device and winding or unwinding the respective positioning cables.

[0002] In load transport devices of the type mentioned above, the load carrier is suspended by means of positioning ropes from spatially distributed and spaced-apart suspension devices. By appropriately winding and unwinding the positioning ropes on the respective positioning winches, the load carrier can be moved back and forth within the working area between the suspension devices, in order to transport loads suspended from the load-handling device and thus from the load carrier from one location to another in the area between the suspension devices.

[0003] An example of a load transport device is shown in DE 10 2009 050 729 A1, which discloses the preamble of claim 1.

[0004] A load-bearing platform with a rectangular base is provided as the load carrier. Positioning cables are attached to the respective corners of this platform. The load transport system further includes a computer system with a control unit for operating the positioning cable winches.

[0005] Sensors determine the actual lengths of the positioning cables and feed this data to a control unit connected to the control unit. The control unit evaluates the measured actual cable lengths and compares them to the target values ​​for the positioning cables, compensating for any deviations between the target and actual cable lengths.

[0006] Regarding the state of the art, reference is also made to the following scientific work: Dokument P1: Etienne Picard, Elias Tahoumi, Franck Plestan, Stéphane Caro, Fabien Claveau. A new control scheme of cable-driven parallel robot balancing between sliding mode and linear feedback. The 21st IFAC World Congress (IFAC 2020), Jul 2020, Berlin, Germany .

[0007] Document P1 discloses an experimental load handling device for manipulating steel plates of varying shapes and masses, in which a method of the type mentioned above is implemented. The load handling device includes cable force sensors arranged at the cable anchor points of a platform to determine the weight of the steel plate held by the load-handling device. This scientific work investigates the dynamics during the traversal of a predetermined load carrier path, employing computationally intensive real-time calculations of the target cable lengths for the positioning cables in various control concepts. The main focus of the approaches presented in this work is on determining the dynamics and repeatability of the traversal with the load-handling device under different weights.The control system incorporates a simplified rope model that calculates the positioning ropes as straight rope sections and takes into account the inelastic behavior of the positioning ropes.

[0008] Determining valid solutions for the target rope lengths of the positioning ropes is complex due to the geometric conditions and kinematics of the load transport device that must be taken into account. This is because, due to the generally existing overdetermination of the static system, several solutions for the target rope lengths are determined, which then have to be reduced to a plausible solution in real time using the control device.

[0009] The object of the invention is to provide an improved method of the type mentioned above in which the computational effort in the control device is reduced and a reliable determination of the target rope lengths to be set is achieved.

[0010] According to the invention, this is achieved by a method with the features of claim 1. .

[0011] In the method according to the invention, the control device has a database in which a plurality of data records are stored, wherein in each data record a pre-calculated target rope length is stored for predefined target coordinates of a predefined target point and a predefined load value for each of the positioning ropes, and the target rope lengths of the positioning ropes to be set by the respective positioning rope winch are determined by the control device by means of a query in the database, by searching for at least one data record in the database for each of the positioning ropes that matches the currently set target coordinates of the target point and the current load measurement value, and the target rope length to be set of the respective positioning rope is determined on the basis of the pre-calculated target rope length of the at least one matching data record.

[0012] The basic idea of ​​the invention is therefore to pre-calculate the target rope lengths of the positioning ropes for a multitude of predefined, particularly assumed, target points and predefined, particularly assumed, load values, and to store these pre-calculated target rope lengths together with the associated target coordinates and load values ​​as data records in a database of the control device. In other words, the results of a multitude of target point and load value scenarios for the operation of the load transport device, expressed by the corresponding pre-calculated target rope lengths, are stored in the database of the control device. The target rope lengths of the positioning ropes to be set by winding and unwinding are determined by the control device by means of a query in the database, i.e., by looking up values ​​of already pre-calculated target rope lengths.

[0013] The method according to the invention eliminates the need for computationally intensive real-time calculation of the target rope lengths of the positioning ropes in the control unit. Since the database for a set of predefined target coordinates of a predefined target point and a predefined load value for each positioning rope contains exactly one data set with exactly one pre-calculated target rope length, the target rope lengths of the positioning ropes can be determined simply, quickly, and reliably using the method according to the invention. In particular, the method according to the invention eliminates the need to store boundary conditions, quality criteria, plausibility checks, etc., in the control unit, thus allowing it to be designed with less complexity and lower computing power.

[0014] By controlling the load movement according to the inventive method, it is possible to react easily to changing load measurements. In particular, when picking up the load from the ground, the rope forces in the positioning ropes increase rapidly until the load is lifted above the ground. Therefore, depending on the load's position in the workspace, the distribution of the target rope lengths of the positioning ropes must be adjusted to prevent the load from pivoting or swaying when it is completely lifted from the ground. Furthermore, in applications where bulk material is transported using the load-handling device, e.g.,If the load-handling device includes a bulk material grab designed in the form of a clamshell bucket, it reacts to load changes during loading and, in particular, unloading of the bulk material by continuously adjusting the actual rope lengths to the set target rope lengths of the positioning ropes, thus preventing the load-handling device from oscillating. This ensures that the load, especially the bulk material, can be loaded or unloaded by the load-handling device at its destination. Furthermore, the method according to the invention allows any obstacles and / or the topography of the ground to be taken into account when controlling the rope lengths.

[0015] The term "predefined target coordinates" refers to the coordinates of discrete, assumed points within the workspace. These points can be determined, for example, by an algorithm that divides the space into discrete sections with a predefined granularity or step size. The term "predefined load values" refers to load values ​​that vary from a minimum value, e.g., no load (= 0 kilograms), to a maximum load value. The step sizes between the minimum and maximum values ​​can be defined according to the specific requirements of the load handling equipment and are stored accordingly in the database.

[0016] The workspace is the space between the suspension devices in which the load attached to or picked up by the load-handling device can be transported from one location to another by the load-carrying device. In other words, the target coordinates of predefined target points stored in the database describe locations within the workspace that the load-handling device can reach.

[0017] The term "rope" is to be understood in a general sense. It refers to an elongated, flexible element, particularly one that is pliable, capable of withstanding tension and can be wound onto a winch. The term "rope" can refer to a rope in the narrower sense, such as a steel cable, but also to a strap, chain, or similar material. For the sake of linguistic simplicity, all of these are subsumed under the term "rope." This applies both to positioning ropes and to other ropes used in the load-carrying equipment, such as the lifting rope mentioned below.

[0018] The rope in question can be a single rope. Accordingly, the singular form is used here for the rope. Of course, the rope, referred to in the singular for the sake of linguistic simplicity, can also be realized by several ropes, especially those running parallel to each other, or as a rope bundle, or as a rope lashed together like a pulley system.

[0019] The load carrier is the component to which the positioning cables attach, each with its end furthest from the respective suspension device. The load carrier is thus suspended from the suspension devices by means of these positioning cables. By operating the positioning cable winches—in other words, by winding or unwinding the respective positioning cable onto or off the respective winch—the load carrier can be moved within or above the work area. It is clear that it is usually necessary to wind or unwind all positioning cables to move the load carrier.

[0020] The load-bearing device is the part of the load-carrying equipment that serves to attach the load to the load carrier. It can be, for example, a... . to use a hook or a mechanical or magnetic grab, a shovel, a scraper, a bulk material grab, e.g. .This could involve a two- or multi-shell gripper, or the like, depending on the type of load to be transported by the load handling device. Virtually all load-handling devices known in the prior art and suitable for the respective application could be used to implement the invention.

[0021] The load transport device could also be called a cable robot.

[0022] The load handling device has at least three positioning cables and, accordingly, at least three suspension devices arranged at intervals. In other embodiments, the load handling device may also have more than three positioning cables, for example, four, five, or six, and a corresponding number of suspension devices. The suspension devices are preferably, but not necessarily, spaced as evenly as possible from one another, for example, so that, in a top view, they are each located at the corners of a closed polygon.

[0023] The suspension devices are the fixtures from which at least one of the positioning cables is suspended. Existing suspension points in the terrain or area where the load-carrying device is to operate can be used to construct the suspension devices. These could be, for example, existing walls in buildings or, in the case of natural topography, rock faces, promontories, or other points, preferably elevated above the surrounding area. Alternatively, at least one, and preferably all, of the suspension devices may include at least one mast or tower, on which the positioning cable winch and / or a deflection pulley for the positioning cable suspended from the respective suspension device is mounted. The positioning cable winch can be positioned at an elevated point or even at the highest point of the mast or tower.In this case, deflection pulleys for the respective positioning cable on the suspension device may be omitted. However, it is also possible to position the positioning cable winch further down, particularly on the suspension device. In this case, it is generally advantageous for the positioning cable to be guided over a deflection pulley on the suspension device, which is located above the positioning cable winch on the respective suspension device.

[0024] The term "control system" is broadly defined and, with regard to hardware, includes, for example, programmable logic controllers (PLCs) or industrial computers (also known as industrial PCs), or other computers and combinations thereof. The concept of controlling the movement of the load can encompass control processes, such as adjusting the rope lengths of positioning ropes when the actual rope length deviates from the target length. On the other hand, the control system can also perform control processes, such as directly controlling the positioning winches or other actuators of the load handling system. All these processes, regardless of whether they are strictly speaking control or regulation, are described in this document as being carried out by means of the control system of the load handling system.

[0025] The recording of currently set target coordinates of a target point in the workspace towards which the load-bearing device is to be moved can be done, for example, by directly entering the desired target coordinates, for example, using an input device such as a keyboard.

[0026] In a preferred embodiment, the target coordinates to be set are calculated by a target coordinate conversion unit of the control device from a target velocity vector output by a motion control unit of the load transport device. For example, the motion control unit can be an input device, in particular a joystick or similar. The target velocity vector output by the input device is then converted into the target coordinates to be set by the target coordinate conversion unit. The conversion of target velocity vectors into target coordinates is generally known. In addition to or as an alternative to input via an input device, it is also conceivable and possible for the motion control unit or an additional motion control unit to have a path planning interface for pre-calculating the desired trajectories, i.e.,The path of the load-handling device or the load itself is determined by the trajectory. Such path planning interfaces are generally known. For example, the path planning interface can be fed with planning data containing target points to be processed and / or work orders for the load transport device.

[0027] The load measurement value can be determined by measuring the weight of the load held by the load-handling device directly using a load measuring device arranged on the load-handling device, which outputs the load measurement value to the control device. Examples of such load measuring devices are: . in the form of load cells and / or load pins, etc., are well known. Alternatively, the weight can be measured indirectly, e.g. . by measuring the rope forces in the positioning ropes using the load measuring device. Such devices are also known in the prior art.

[0028] The terms "actual rope length" and "target rope length" of the respective positioning rope refer to a length value of the respective positioning rope used to determine the actual or target position of the load carrier and the load-bearing device. This can be the length of the positioning rope unwound from the respective positioning winch to an anchor point on the load carrier, or, if the respective positioning winch is located in a lower area of ​​the suspension device and the positioning rope is guided over the aforementioned deflection pulley, the length of the positioning rope between the deflection pulley and the anchor point on the load carrier.

[0029] The actual length of each positioning cable can be determined, for example, by an absolute encoder mounted directly on the positioning winch or by an absolute encoder mounted on the winch drive. The absolute encoder can be, for example, a rotary encoder. By recording the number of revolutions of the positioning winch, the length of the section unwound by the winch or the length of the section of the positioning cable extending between the deflection pulley and the load carrier can be calculated.

[0030] The data records stored in the database can be stored, for example, in the form of a file. Alternatively, the data records could be in the form of a table, similar to a relational database. In other words, the database can generally be a database. Furthermore, it is conceivable and possible that the data records stored in the database are indexed, for example, using a so-called hash table or scatter table, to facilitate or speed up the retrieval of specific data records within the large dataset.

[0031] As previously explained, each data record relates to one of the positioning cables, containing the pre-calculated target cable length for a given target coordinate of a target point and a given load value. The control unit searches the database for at least one matching data record for the currently set target coordinates of the target point and the current load measurement. If the actual cable length of one of the positioning cables deviates from the set target cable length, the respective positioning cable winch is controlled by the cable length control system.

[0032] For example, it could be intended that exactly one suitable nearest data record is searched for in the database, e.g. the data record closest to the specified target coordinates with the nearest specified load value, whereby the pre-calculated target rope length of this data record is then used directly as the target rope length to be set for the respective positioning rope.

[0033] It is particularly advantageous if the control unit searches the database for at least two data records closest to the target coordinates of the target point and the current load measurement for each positioning cable, and the target cable length to be set for each positioning cable is determined by interpolation based on the pre-calculated target cable lengths of the two nearest data records. This interpolation allows the target cable length to be approximated from the discrete, pre-calculated target cable lengths stored in the data records. This increases the positioning accuracy of the load-handling device and / or the load itself.

[0034] In a simple case, interpolation can be linear, based on the two nearest matching data sets. However, it is also conceivable and possible to perform trilinear interpolation (i.e., in three-dimensional space) or interpolation in four-dimensional space. Such interpolation methods are known in a variety of forms. In principle, apart from linear interpolation methods in one- or multi-dimensional space, other interpolation methods, such as polynomial interpolation, are also conceivable and possible, as is well known.

[0035] Preferably, the cable length control system includes a feedforward control function for the set target cable length of the positioning cables. Providing this feedforward control improves the guidance behavior of the cable length control system.

[0036] Preferably, the pre-calculation of the predetermined target rope lengths of the positioning ropes is carried out in a data processing step of the method in a data processing unit of the load transport device that is separate from the control unit, wherein a model of the indirect kinematics of the load transport device and an optimizer are stored in the data processing unit, and the model of the indirect kinematics and the specified load values ​​as well as the specified target coordinates of the specified target points are supplied to the optimizer, and the optimizer uses the model of the indirect kinematics to determine valid solutions for the target rope lengths of the positioning ropes for the specified load values ​​at the specified target coordinates.and the valid solutions, as the pre-calculated target rope lengths of the positioning ropes together with the respective associated load value and the respective specified target coordinates, are stored by the data processing unit in the database of the control unit as one of the data records.

[0037] The storage of valid solutions as data records in the control unit's database can be done once, for example, during the initial commissioning of the load handling system. This means that a data connection between the data processing unit and the control unit of the load handling system may be interrupted, at least temporarily, after the data records have been stored in the database. During initial commissioning, the basic parameters of the load handling system must be entered into the indirect kinematics model. If significant parameters of the load handling system change, for example, due to changes in the position or orientation of the suspension devices or a change in the dead weight, etc., new data records with pre-calculated target rope lengths based on the changes in the indirect kinematics model can be generated.The changed parameters of the load transport device are calculated and stored in the control device's database as a replacement for the existing data sets.

[0038] Indirect kinematic models are well-known in robotics. In the present case of load transport systems, the indirect kinematic model provides the computational framework that contains the physical relationships of multiple positioning cables attached to a load carrier. These relationships can lead to over-constraints, particularly when multiple positioning cables are attached to a single load carrier. Specifically, the indirect kinematic model, which can also be called the inverse kinematic model, represents the dependence of the target cable lengths of the positioning cables on each other and on the predetermined target coordinates of the specified target points and the predetermined load values.

[0039] The term "optimizer" refers to a unit for the numerical solution of the indirect kinematics model. Optimizers are known in various forms in mathematics. The specified target points, for which valid solutions for the target rope lengths of the positioning ropes are determined by the optimizer at the specified load values, are discrete target points of the load transport device in the workspace. These target points can be approached by the load-handling device during operation of the load transport device, taking into account the weight of the load attached to the load-handling device.

[0040] In a preferred embodiment of the method, the specific weight of each positioning cable is taken into account during the data processing step when calculating the pre-calculated target cable lengths in the indirect kinematics model. By considering the specific cable weight in the data processing device, the influence of the sag of the respective positioning cable due to its own weight is factored into the determination of the pre-calculated target cable lengths.By pre-calculating the target rope lengths in the data processing unit, a complex model of the indirect kinematics of the load transport device can be considered in the data processing step without affecting the processing speed of the control unit itself, since the results of the pre-calculated target rope lengths of the data sets also take into account the sag of the respective positioning rope. If the specific weight of the respective positioning rope is also considered, the indirect kinematics model could also be referred to as an extended indirect kinematics model.

[0041] To calculate exactly one target rope length in advance for each of the positioning ropes, given a specific set of target coordinates, a given target point, and a given load value, optimization conditions are usually used during optimization.

[0042] It is particularly preferred that the data preparation step includes at least one optimization condition: minimum sag of the positioning cables; minimum cable force of the positioning cables; minimum sum of the cable forces of the positioning cables; maximum permissible cable force of the respective positioning cable; minimum difference in the cable forces of the positioning cables; elastic deformation of the suspension devices; underlying principle.

[0043] For example, considering the optimization condition of minimal sag in the positioning cables can prevent an unacceptable result in indirect kinematics, where a sagging positioning cable touches the ground. Another example of a possible optimization is the principle of minimum energy when lifting the load-handling device. Such optimization conditions, as well as others not mentioned, are well known in the field of optimization computation.

[0044] In a particularly preferred embodiment of the method, a meshing algorithm is applied in the data preparation step. This algorithm meshes the specified target coordinates into a computational mesh, in particular a polygon mesh, as computational mesh data. The computational mesh data includes linking data for linking adjacent target coordinates of the specified target point of the load-bearing device and adjacent load values. The computational mesh data is stored in the database of the control device, and the control device takes the computational mesh data into account when determining the target rope length to be set for the respective positioning rope. By providing a computational mesh, more accurate results for the target rope lengths of the positioning ropes in the workspace can be determined, taking into account specified load values. For example, the polygon mesh can be...It is about a tetrahedral net.

[0045] It is particularly preferred that the data preparation step includes an iterative algorithm for densifying the computational grid in the boundary regions of the workspace, whereby pre-calculated target rope lengths of the positioning ropes are determined for additional coordinates of additional positions of the load-bearing device. Densifying the computational grid allows the number of target points in the boundary regions of the workspace to be increased, thereby enlarging the workspace in these areas and improving the accuracy of determining the target rope lengths. Such algorithms are known, for example, from the field of finite element methods.

[0046] It is particularly preferred if the iteration algorithm for densifying the computational grid is a Delaunay triangulation.

[0047] Preferably, the method includes a step of capturing design parameters for calculating the pre-calculated target rope lengths of the positioning ropes in the data preparation step, wherein the design parameters include at least one of the following characteristic values: the position of the rope exit points of the suspension devices, at which the respective positioning rope runs from the respective suspension device in one direction towards the load carrier; the positions of the positioning rope winches; the specific rope elongation of the respective positioning rope; the stiffness of the respective suspension device; the dead weight of the load carrier; the dead weight of the load-bearing device; the center of mass of the load carrier and / or the load-bearing device.

[0048] For example, the material properties of the specific elongation of the respective positioning cable can be stored. The stiffness of the respective suspension device describes the column deformation under different load values ​​and / or target coordinates. For example, the column deformation can be determined by measuring it using a calibration load attached to the load-bearing device. Additional design parameters can also be used in the data processing unit to calculate the pre-calculated target cable lengths of the positioning cables, such as inertias, coefficients of friction, etc., which influence the characteristics of the load handling device. Furthermore, the design parameters can include geometric data of obstacles or restricted areas in the working space of the load handling device, e.g.,Machine parts located in the work area that obstruct the free movement of the load-handling device in the work area.

[0049] It is expedient that all previously specified coordinates, e.g. the specified target coordinates, positions such as the position of the positioning winches, etc., refer to a reference coordinate system that is defined in relation to the load transport device.

[0050] It is possible for the load-bearing device to be fixed directly to the load-bearing structure. For example, the load-bearing device could be suspended from the load-bearing structure by a fixed-length rope or chain anchored to it, i.e., at a defined distance from the load-bearing structure. Alternatively, the load-bearing structure could be fixed directly to the load-bearing structure.

[0051] In a preferred embodiment, the load transport device has a lifting winch and a lifting rope, wherein the lifting rope can be wound up and unwound from the lifting winch, and the load-bearing device is suspended from the load carrier by means of the lifting rope and can be raised and lowered relative to the load carrier.

[0052] By suspending the load-handling device from the load carrier using the lifting cable, and thus being able to raise and lower the load-handling device relative to and from the load carrier using the lifting cable, the working area of ​​the load transport device is significantly increased compared to other designs of load transport devices, particularly at the edges of the working area. The lifting winch can, for example, be arranged on the load carrier, and an electrical power supply line for the drive motor of the lifting winch can be integrated into at least one of the positioning cables. Alternatively, this power supply line can be a separate line to the lifting winch. The lifting winch can also be powered by a battery that is charged or replaced outside of operating hours.

[0053] Alternatively, it is conceivable and possible for the lifting winch to be mounted on one of the suspension devices. The load carrier can then have a deflection pulley, with the lifting cable running from the lifting winch over the deflection pulley to the load-handling device.

[0054] If a lifting rope is present, the procedure preferably additionally comprises the following steps: determining the actual length of the lifting rope; determining the target length of the lifting rope to be set by the lifting rope winch by winding or unwinding for the currently set target coordinates and the current load measurement, wherein a pre-calculated target length of the lifting rope is stored in each data record for the specified target coordinates of each of the specified target points and for each of the specified load values ​​for the lifting rope, and the target length of the lifting rope to be set by the lifting rope winch by winding or unwinding is determined by the control device by means of a query in the database.The control unit for the lifting rope searches the database for at least one data set matching the currently set target coordinates of the target point and the current load measurement. Based on this pre-calculated target rope length of the lifting rope, the target rope length is determined. The actual length of the lifting rope is then adjusted to the target length by controlling the lifting rope winch using the control unit's rope length control and winding or unwinding the lifting rope. This means that any lifting rope of the load transport device can be treated analogously to the positioning ropes, with all process steps relating to the positioning ropes also being applied analogously to the lifting rope or other ropes.

[0055] Further features and details of the method according to the invention and its application in a load transport device are explained by way of example in the following description of the figures. They show: Fig. 1 a simplified overall view of a load handling device including a schematic workspace in an isometric representation; Fig. 2 an isometric representation of a load handling device with three enlarged detail views A to C ; Fig. 3 the load transport device according to Fig. 2 when picking up a load; Fig. 4 the load transport device according to Fig. 2 during the transport of the load in the work area; Fig. 5 a schematic representation of the control of the positioning winches and the lifting winch of the load transport device according to Fig. 2 ; Fig. 6 shows a schematic detail view of a data processing unit and a control unit of the load transport unit according to Fig. 2 ; Fig. 7 a symbolic representation of an optimization step for determining data sets for a database of the control device; Fig. 8 a simplified representation of a working space determined by the data processing device with valid solutions for calculated target rope lengths; Fig. 9 an alternative embodiment of the control device according to Fig. 6 with a feedforward control; Figs. 10a to 10e depict a simplified two-dimensional view of the process of picking up a load from a substrate using the load-bearing device and the method according to the invention in five steps a to e; Fig. 11 a diagram of the course of the actual rope lengths of the positioning ropes in the five steps a to e according to Fig. 10a bis 10e , and Fig. 12 a diagram of the course of the rope forces in the positioning ropes in the five steps a to e according to Fig. 10a bis 10e ;

[0056] Fig. 1 Figure 1 shows a simplified representation of a load transport device 1 with four suspension devices 9 in the form of masts, each with positioning cables 6a, 6b, 6c, 6d suspended from it. The positioning cables 6a-d run from the respective suspension device 9 to a load carrier 4, which is suspended from the suspension devices 9 by means of the positioning cables 6a-d. A load-bearing device 5 for receiving a load is attached to the load carrier 4. In the representation of the Fig. 1 This load-handling device 5 is designed as a hook, wherein the load-handling device 5 is attached to the load carrier 4 by means of a lifting cable 10 of the load transport device 1 and hangs from the load carrier 4. The load-handling device 5 is in the Fig. 1 The illustrated version can be raised and lowered relative to the load carrier 4. This is achieved by winding and unwinding the positioning cables 6a-d onto the in Fig. 1 Without the positioning winches 7 (not shown), the load carrier 4, together with the load-bearing device 5, can be moved in the area between the suspension devices 9 to pick up loads 3, transport them to another location, and place them back down on the surface of the ground 14. By providing a lifting cable 10, the peripheral area near the suspension devices 9 can also be easily accessed. The in Fig. 1 The simplified workspace 2 defines the space between the suspension devices 9 in which the load attached to or picked up by the load-handling device 5 can be transported from one location to another by the load-carrying device 1. The workspace 2 is generally smaller than the space between the suspension devices 9, as can be seen by comparing the solid lines of the workspace 2 with the space spanned by the suspension devices 9, which is shown in Fig. 1 as indicated by the dashed lines.

[0057] The procedure for controlling the movement of the load 3 in the workspace 2, which will be explained below, can be implemented, as described at the beginning, for load transport devices 1 with only three positioning ropes and correspondingly only three suspension devices, but especially also with more than three, i.e., four, five, or six, etc., positioning ropes and suspension devices. The suspension devices are advantageously located, viewed from a top view of the surface of the substrate 14, at the corners of an imaginary, closed polygon, which, with three suspension devices, is a triangle. In the case of the Fig. 1 The four suspension devices 9 shown are the suspension devices 9 ,Viewed from above, the surface of the substrate 14 forms a rectangle or a square, or more generally, a quadrilateral. With five suspension devices, viewed from above, they form a pentagon, and so on.

[0058] In Fig. 1 The load carrier 4 is shown only schematically, with one of the positioning cables 6a to 6d attached to each corner point of the load carrier 4. The lifting winch 11 (not shown) can be arranged on the load carrier 4 or, as is the case with the [unclear] Fig. 2 bis 4 The load transport device 1 shown is implemented on one of the suspension devices 9. All of this is known in the prior art.

[0059] In the Fig. 2 bis 4 An example of a load transport device 1 is now shown, with reference to which the method according to the invention is explained. The respective suspension device 9 has two unspecified compression supports and one weight-weighted tension support, which rests on the base 14. Each suspension device 9 has a positioning winch 7 for winding and unwinding one of the positioning cables 6a-6d. In the illustrated embodiment, the positioning winches 7 are each arranged in a region of the suspension device 9 close to the base 14.

[0060] The detailed illustrations A to C, each marked with a dashed circle, show details of the load transport device 1 of the Fig. 2 Highlighted. Detail A shows, by way of example, one of the positioning winches 7, which serves to wind and unwind the positioning cable 6d. Each positioning winch 7 has a positioning winch drive 8, which in the exemplary embodiment is designed as a motor-gearbox unit for driving the unspecified cable drum; see also Detail B. .

[0061] At the in Fig. 2 bis 4 In the illustrated load transport device 1, the lifting cable 10 is guided from the load carrier 4 to one of the suspension devices 9, wherein a lifting cable winch 11 for winding and unwinding the lifting cable 10 is arranged in a ground-level area of ​​the suspension device 9, cf. Detail B of the Fig. 2 The lifting winch 11 has a lifting winch drive 12, which is designed as a motor-gearbox unit.

[0062] The load-bearing device 5 is designed as a hook, which serves to hold the load 3, see detail C of the Fig. 2 .The lifting rope 10 is connected to the load-bearing support 4 in a pulley-like configuration between the hook and an unspecified deflection pulley, and is anchored to the hook. Such pulley systems are known in various forms. Instead of a hook, the load-bearing device can also be designed differently depending on the application, as already explained. For the method of controlling the movement of the load 3 in the workspace 2, the design of the load-bearing device 5 is of secondary importance.

[0063] At the in Fig. 2 bis 4 In the load transport device 1 shown, the load carrier 4 is designed in the form of a traverse, with three of the positioning cables 6a, 6b and 6d attaching to one end of the traverse and the positioning cable 6c attaching to the load carrier 4 at the opposite end of the traverse. The lifting cable 10 runs parallel to the positioning cable 6c to the same suspension device 9. .

[0064] The respective positioning ropes 6a-d and the lifting rope 10 run in the area of ​​the suspension devices 9 from the rope drum essentially in a vertical direction to a deflection pulley 13 located opposite the base 14 and arranged on the suspension device 9, and from there to the load carrier 4. .

[0065] In the Fig. 3 und 4 Two exemplary positions of the load carrier 4 or the load-bearing device 5 and the load 3 are now shown. In the Fig. 3 In the depicted state, the load 3 picked up by the load-bearing device 5 is lifted from the ground 14 by the load-bearing device 5. Fig. 4 Figure 1 shows a state in which the load 3, lifted from the base 14, is transported to a destination within the workspace 2. Lifting and transporting the load 3 within the workspace 2 is accomplished by winding and unwinding the respective positioning rope 6a-d onto and off the positioning winch 7 and / or by winding and unwinding the lifting rope 10 onto and off the lifting winch 11. For clarity, the positioning winches 7 and the lifting winch 11 are shown in Figure 1. Fig. 3 und 4 not shown.

[0066] In Fig. 5 The components of the load transport device 1 for controlling the positioning winches 7 and the lifting winch 11 are now shown in simplified form to explain the method according to the invention in detail. The positioning winch drives 8 and the lifting winch drive 12 are also shown in simplified form. In the exemplary embodiment, each positioning winch drive 8 and the lifting winch drive 12 has an absolute encoder 25 for detecting the rotational position of the positioning winches 7 and the lifting winch 10, respectively. The actual length of the positioning cable 6a-d and the lifting cable 10 unwound by the respective positioning winch 7 and lifting winch 10 can be determined by means of the absolute encoder 25.

[0067] The load transport device 1 further comprises a control device 20, which serves to monitor and regulate the cable lengths of the positioning cables 6a-d. In the exemplary embodiment, the control device 20 is a combination of a programmable logic controller (PLC) and an industrial computer. Other embodiments of the control device 20 are also possible, as mentioned at the outset.

[0068] The values ​​output by the absolute encoders 25 are converted into actual rope length values ​​in the control unit 20, which is not shown separately in the figures. These actual rope length values ​​are fed to a rope length control unit 22, which compares the measured actual rope lengths with predetermined target rope lengths (to be explained later) and, based on this comparison, adjusts the actual rope lengths of the positioning ropes 6a-d by winding or unwinding them, and also adjusts the actual rope length of the lifting rope 10 by winding or unwinding it.

[0069] In the exemplary embodiment, a frequency converter 33 of the load transport device 1 is connected downstream of the rope length control 22, which controls the positioning winch drives 8 and the lifting winch drive 12. In another embodiment, the rope length control 22 could be part of the frequency converter 33. Such embodiments of frequency converters are well known.

[0070] Furthermore, the load transport device 1 has a load measuring device 21 which is located in Fig. 5 This is also only shown schematically. In the exemplary embodiment, the load measuring device 21 is arranged on the load-bearing device 5 and makes it possible to measure the weight of the load 3 picked up on the load-bearing device 5.

[0071] The control unit 20 has a data query unit 41 to which the load measurement value output by the load measuring device 21 is supplied.

[0072] Furthermore, the load transport device 1 has two motion control devices. One motion control device, designated as input device 26, serves to detect the currently set directions of movement of the load handling device 5. Fig. 5 The input device 26 is depicted as a joystick, which can be operated by an operator of the load transport device 1 to directly issue travel commands. A target velocity vector output by the input device 26 is converted in a target coordinate conversion unit 28 of the control device 20 into the currently set target coordinates of a target point towards which the load handling device 5 is to be moved. Such target coordinate conversion units 28 are well known.

[0073] In the exemplary embodiment, the further motion control device of the load transport device 1 is a path planning interface 27, which is located in Fig. 5 This is also only shown schematically. In this embodiment, the input data output by the path planning interface 27 is also in the form of a input velocity vector and is fed to the target coordinate conversion unit 28, which converts the input velocity vector into the target coordinates to be set for a target point towards which the load-handling device 5 is to be moved. It would also be conceivable and possible for the path planning interface 27 to provide other input data in addition to velocity vectors, such as acceleration values, jerk values, etc. In this case as well, the target coordinate conversion unit 28 uses the data provided by the path planning interface 27 to determine the target coordinates to be set for the target point towards which the load-handling device 5 is to be moved.

[0074] The path planning interface 27 can be located remotely from the control unit 20, which is indicated by a break symbol in the connecting line between the path planning interface 27 and the target coordinate conversion unit 28. Fig. 5 The path planning interface 27 can, for example, be linked to path planning software of a central computer used to plan the work processes of the load-handling device 5 in the workspace 2, which is not shown separately. The path planning software allows specifications to be made regarding a planned movement path of the load-handling device and / or the velocity and / or acceleration and / or jerk of the load-handling device relative to the movement path. Such central computers and corresponding path planning software are well known.

[0075] The control unit 20 has a database 23 arranged in the data query unit 41 of the control unit 20. A large number of data records are stored in the database 23.

[0076] Each data record stored in database 23 contains, for each of the positioning ropes 6a-d, and in the exemplary embodiment also for the lifting rope 10, a pre-calculated target rope length of the respective positioning rope 6a-d and the lifting rope 10, for predefined target coordinates of a predefined target point and a predefined load value.

[0077] The specified target coordinates refer to a reference coordinate system defined in relation to the load transport device 1. Using this reference coordinate system, all points in the workspace 2 can be uniquely described.

[0078] The method for controlling the movement of the load 3 in the working space 2 of the load transport device 1 by means of the control device 20 now comprises a sequence of steps: In a first step, the target coordinates of a target point in the working space 2, towards which the load handling device 5 is to be moved, are determined. In the exemplary embodiment, this step is carried out by means of the target coordinate conversion unit 28, which transmits the target coordinates to the data query unit 41.

[0079] Furthermore, a load measurement value is determined by measuring the weight of the load 3 picked up by the load-handling device 5 using the load measuring device 21. The load measuring device 21 can be arranged directly on the load-handling device 5, e.g., on the hook, as is known per se. Alternatively, the load measurement value can be determined indirectly by a load measuring device 21 arranged on the lifting winch 11, e.g., by means of one or more force-measuring bolts at an anchorage of the lifting winch 11 or by measuring the required torque of the lifting winch 11. Such designs of load measuring devices 21 are also well known. Optionally, the length of the lifting cable 11 unwound by the lifting winch 11 can be taken into account when determining the load measurement value.Furthermore, an indirect measurement of the weight of the load 3 can be achieved using the load measuring device 21 by determining the rope forces in the positioning ropes 6a-6d, preferably taking into account the rope length unwound by the respective positioning winch 7. If the lifting winch 11 is arranged on one of the suspension devices 9, as provided in the exemplary embodiment, an indirect measurement of the weight of the load 3 using the load measuring device 21 can be carried out by measuring the rope forces of the positioning ropes 6a-6d and by measuring the rope force of the lifting rope 10, taking into account the rope length unwound by the respective positioning winch 7 and the lifting winch 11, respectively.

[0080] The determination of the current position of the load handling device 5 in the working space 2 is carried out by determining the actual rope lengths of the positioning ropes 6a-d and, in the exemplary embodiment, also by determining the actual rope length of the lifting rope 10.

[0081] The target rope lengths to be set for the positioning ropes 6a-d and the lifting rope 10 are determined by the control unit 20 by means of a query in the database 23. For this purpose, the control unit 20 searches for at least one data record in the database 23 for each of the positioning ropes 6a-d and the lifting rope 10 that matches the currently set target coordinates of the target point and the current load measurement. The target rope length to be set for the respective positioning rope 6a-d and the lifting rope 10 is then determined based on the previously calculated target rope length of the at least one matching data record. The determination of the target rope length and possibilities for improving the accuracy of the target rope length are discussed further below.

[0082] In addition, the actual rope lengths of the respective positioning ropes 6a-d are adjusted to the target rope lengths of the respective positioning ropes 6a-d and the actual rope length of the lifting rope 10 is adjusted to the target rope length of the lifting rope 10 by controlling the respective positioning winch 7 or the lifting winch 11 by means of the rope length control 22 of the control device 20.

[0083] As long as the load measurement value and the target coordinates to be set do not change, and as long as the actual rope length of the respective positioning rope 6a-d and the lifting rope 10 deviates from the target rope length to be set for the respective positioning rope 6a-d and the lifting rope 10, the rope length control 22 adjusts the actual rope length to the target rope length to be set for the respective positioning rope 6a-d and the lifting rope 10 until the actual rope length of each positioning rope 6a-d and the lifting rope matches the respective target rope lengths.

[0084] If the target coordinates to be set change due to a changed target velocity vector and / or due to a changed load measurement, e.g., as a result of picking up or unloading a load 3, the data query unit 41 queries the database 23 for new target rope lengths to be set for the positioning ropes 6a-d and the lifting rope 10. This means that the rope length control 22 receives new target rope lengths to be set for the positioning ropes 6a-d and the lifting rope 10, and then adjusts the actual rope length to the newly set target rope length of the respective positioning rope 6a-d and the lifting rope 10 until the actual rope length of each positioning rope 6a-d and the lifting rope 10 matches the respective target rope lengths to be set.

[0085] A simple example of the data records stored in database 23 is given below. The designation XYZG assigns the following example values, enclosed in square brackets, to the predefined target coordinates X, Y, and Z of a given target point, and G to a corresponding load value assumption, which is a constant 1 in the example data. For the sake of simplicity, the values ​​of the target coordinates in the X and Y directions are also a constant 1 in the example data. Only the target coordinate Z changes between the values ​​1, 2, and 3 in the example data. XYZG[1,1,1,1].Positioning rope[1] := 2882.0; XYZG[1,1,1,1].Positioning rope[2] := 2594.2; XYZG[1,1,1,1].Positioning rope[3] := 1136.5; XYZG[1,1,1,1].Positioning rope[4] := 1906,4; XYZG[1,1,2,1].Positioning rope[1] := 2858.9; XYZG[1,1,2,1].Positioning rope[2] := 2548.1; XYZG[1,1,2,1].Positioning rope[3] := 1039.8; XYZG[1,1,2,1].Positioning rope[4] := 1847.0; XYZG[1,1,3,1].Positioning rope[1] := 2843.5; XYZG[1,1,3,1].Positioning rope[2] := 2503.9; XYZG[1,1,3,1].Positioning rope[3] := 943.7; XYZG[1,1,3,1].Positioning rope[4] := 1789.9; ...

[0086] For each of the positioning cables, whose assignment is determined by the number of the respective positioning cable indicated in the corresponding square brackets, the target cable length to be set is pre-calculated and stored. For example, for positioning cable[1] with the specified target coordinates X=1, Y=1, Z=1 and the specified load value G=1, the target cable length to be set is 2882.0.

[0087] It can now be provided that the target rope lengths of the positioning ropes 6a-d to be set by the respective positioning winch 7 by winding or unwinding are determined by the control unit 20 by means of a query via the data query unit 41 in the database 23, by the control unit 20 searching for a suitable data record in the database 23 for each of the positioning ropes 6a-d that is closest to the currently set target coordinates of the target point and the current load measurement value and the target rope length to be set of the respective positioning rope 6a-d is determined on the basis of the previously calculated target rope length of the one suitable data record.

[0088] Returning to the examples of data sets mentioned above, for example, with the target coordinates to be set X=1, Y=1 and Z=2,2 and G=1 for the positioning rope[2], the nearest data set would be sought, and thus the data set XYZG 1 ,1 ,2 ,1 .Positionierseil 2 : = 2548 ,1; found, since it corresponds to the nearest data set with respect to the coordinate Z, etc. If the requirements for the positioning accuracy of the load-handling device 5 are low, the process can continue directly with the found value of the pre-calculated target rope length.

[0089] The values ​​stored in the database are therefore discrete predefined target coordinates on the basis of which, taking into account the predefined load values, the target rope lengths to be set for the positioning ropes 6a-d and also for the lifting rope 10, which was omitted in the example data, are determined.

[0090] In the exemplary embodiment, the data query unit 41 includes an interpolator 32 to increase the positioning accuracy of the load transport device 1. In the method for controlling the movement of the load 3 in the workspace 2, at least two data records in the database 23 are searched for that are closest to the target coordinates of the target point and the current load measurement, and the target rope length of the respective positioning rope 6a to 6d is determined by interpolation based on the pre-calculated target rope lengths of the at least two nearest data records. In the simplest case, the interpolation can be linear. Other, in particular nonlinear, interpolation methods can also be used to further improve the positioning accuracy of the load transport device 1. The interpolator 32 performs the corresponding interpolation in the data query unit 41. Such interpolators 32 are known per se.

[0091] In Fig. 6 The rope length control 22 is shown in more detail with block diagrams. In particular, in Fig. 6 It is evident that each of the positioning ropes 6a-d and the lifting rope 10 has its own separate regulation, which is symbolically indicated by the three points shown.

[0092] In the exemplary embodiment, the rope length control 22 comprises a controller module 39, known per se, and the control loop 40, which is represented symbolically. As already explained, the rope length controller 22 adjusts the actual rope length of the respective positioning rope 6a-d and the lifting rope 10 to the set target rope lengths of the respective positioning rope 6a-d and the lifting rope 10 by controlling the respective positioning winch 7 and the lifting winch 11, respectively. The control of the respective positioning winch 6a-d and the lifting winch 10 is described in Fig. 6 This is symbolized by the control loop 40. Furthermore, in Fig. 6 The determination of the load measurement value by measuring the weight of the load 3 picked up by the load-bearing device 5 using the load measuring device 21 is also symbolically represented. It is clearly evident here that the load measurement value is fed to the interpolator 32 of the data query unit 41, whereby the interpolator 32 determines the target rope length to be set for the respective rope. The target rope length to be set could also be referred to in this context as the control variable for the rope length control 22.

[0093] In the exemplary embodiment, the load transport device 1 has a data processing unit 24, which is separate from the control unit 20. A data connection line, not specified in detail in the figures, between the data processing unit 24 and the control unit 20 is shown in Fig. 5 and 6The data processing unit 24, shown in dashed lines, serves in the exemplary embodiment to determine the pre-calculated target rope lengths of the positioning ropes 6a-d and the lifting rope 10, which will be discussed in more detail below.

[0094] The data connection between the control unit 20 and the data processing unit 24 can be continuously active, but this is not mandatory, as the control unit 20 can operate independently of the data processing unit 24. In particular, it is possible for the data connection between the data processing unit 24 and the control unit 20 to be established only once. z.B. during the initial commissioning of the load transport device 1, or it is established as needed for the input of data sets into the database 23.

[0095] In the data processing unit 24, a model of the indirect kinematics 30 of the load transport device 1 is stored in the exemplary embodiment. The model of the indirect kinematics 30 describes the mathematical framework with which the target cable lengths of the positioning cables 6a-d are calculated in advance based on predefined target coordinates of the predefined target points and predefined load values. For example, the model of the indirect kinematics 30 describes the physical relationships of the cable statics of the respective positioning cable, etc., as already explained at the beginning.

[0096] In preferred embodiments, such as the illustrated example, the indirect kinematics model 30 takes into account the specific weight of each positioning rope 6a-d when calculating the pre-calculated target rope lengths of the positioning ropes 6a-d. Furthermore, it is advantageous to also consider the specific weight of the lifting rope 10. As already explained, when the specific weight of the rope is taken into account, as shown in the illustrated example, the indirect kinematics model 30 could also be referred to as an extended indirect kinematics model.

[0097] Furthermore, the data processing unit 24 includes an optimizer 34 which, taking into account design parameters 29, determines solutions for the indirect kinematics 30 for the target rope lengths of the positioning ropes 6a-d by applying numerical mathematics. Optimizers 34 of this type are known in various forms.

[0098] The design parameters 29 for calculating the pre-calculated target rope lengths of the positioning ropes 6a-d in the data preparation unit 24 can include at least one of the following characteristic values: the position of the rope exit points of the suspension devices 9, at which the respective positioning rope 6a-d runs from the respective suspension device 9 in one direction towards the load carrier 4; the positions of the positioning rope winches 7 and the lifting rope winch 10; the specific rope elongation of the respective positioning rope 6a-d;

[0099] Other characteristics of the load transport device 1 can also be considered as design parameters, as already explained at the beginning.

[0100] The data processing unit 24 contains optimization conditions 35, which serve to determine exactly one plausible solution for the target rope lengths of the positioning ropes 6a-d. In the exemplary embodiment, z.B. It is provided that the optimization condition takes into account the smallest rope force of the positioning ropes 6a-d. Furthermore, z.B. The smallest sum of the rope forces of the positioning ropes 6a-d is used as an optimization condition. Further examples of optimization conditions have already been explained and could, for example, be the smallest sag of the positioning ropes 6a-d. The optimization conditions 35 serve to improve the stability of the optimizer 34 and to ensure the reliability of determining exactly one correct solution for the target rope lengths of the positioning ropes 6a-d.

[0101] Fig. 7 Figure 1 illustrates the process of a data preparation step of the procedure in detail. The specified target coordinates of the specified target points and the specified load values ​​are schematically represented together as predefined data 37 stored in the data preparation unit 24, in the form of a suggested four-dimensional cube with the coordinates X, Y, Z, and G. The granularity, d.h. The number of possible target coordinates, as well as the granularity or step size of the specified load values ​​between a minimum and maximum value, can be specified depending on the area of ​​application of the load transport device 1, as mentioned at the beginning.

[0102] In the data preparation step, the coordinates X, Y, Z of the specified target coordinates and the load values ​​G of the input data 37 are fed to the optimizer 34. The optimizer 34 then uses the model of the indirect kinematics 30, which in this embodiment is extended in particular by taking into account the specific weight of the rope, to determine valid solutions for the input data 37 for the pre-calculated target rope lengths of the positioning ropes 6a-d and the lifting rope 10. These pre-calculated target rope lengths of the positioning ropes 6a-d and the lifting rope 10 are in Fig. 7 generally shown as L1 ... Ln. The valid solutions of the pre-calculated target rope lengths of the positioning ropes 6a-d and the lifting rope 10, as well as the respective load value and the corresponding target coordinates, are subsequently stored as data records by the data processing unit 24 in the database 23 of the control unit 22. The in Fig. 7 The dotted line with arrowhead following data base 23 indicates the connection with interpolator 32, which is located in Fig. 6 is evident.

[0103] It should be noted here that the symbolic representation of the data sets in database 23 and the target data 37 is in accordance with Fig. 7 These are highly simplified representations, as four-dimensional tables and relationships can only be represented in a greatly simplified manner. Each cube in database 23 therefore only symbolically represents the values ​​of one of the positioning cables 6a-d. The in Fig. 7 The three points shown therefore indicate the large number of corresponding four-dimensional data.

[0104] In the exemplary embodiment, a networking algorithm 31 is stored in the data processing unit 24, which converts the specified target coordinates into a computational network, z.B. A polygon mesh, in particular a tetrahedral mesh, is used as computational mesh data. The computational mesh data includes linkage data of adjacent predefined target positions of the load-bearing device 5 and predefined load values ​​of the load 3. . In the exemplary embodiment, this computational network data is also stored in the database 23 of the control unit 20, although this is not shown separately. The computational network data is taken into account by the control unit 20 when determining the target rope length to be set for the respective positioning rope 6a-d and the lifting rope 10. In particular, when using an interpolator 32, the computational network data can be used to quickly locate the nearest matching data sets.

[0105] In the exemplary embodiment, the meshing algorithm 31 is a Delaunay triangulation that uses tetrahedral nets. In a modified form, the meshing algorithm 31 could be omitted, which is why it is shown in dashed lines in the figures.

[0106] In the exemplary embodiment, an iteration algorithm (not explicitly shown) is stored in the data processing unit 24. This iteration algorithm serves to refine the computational grid in the boundary regions of the workspace 2. For additional coordinates of additional positions of the load-handling device 5, pre-calculated target rope lengths of the positioning ropes 6a-d, and in the exemplary embodiment also for the lifting rope 10, are determined in the boundary region of the workspace 2. By densifying the computational grid in the boundary regions of the workspace 2, the workspace 2 can be enlarged, as this results in the determination of additional valid solutions to the pre-calculated target rope lengths.

[0107] In Fig. 8 Figure 2 shows the workspace 2 of the load transport device 1, which represents the predefined target points for which valid solutions for the target rope lengths of the positioning ropes 6a-6d were determined using the optimizer at the specified load values. The individual predefined target points for which the valid solutions were determined are shown in Fig. 8 not explicitly shown. The data describing workspace 2 can additionally be made available to the aforementioned path planning software in order to take into account the accessible areas of the load transport device 1 during path planning.

[0108] Fig. 8 This also illustrates that the positioning ropes 6a-d are subject to sag due to the already mentioned consideration of the specific rope weight in the model of the extended indirect kinematics 30, which can be seen by comparing the dashed straight lines between the deflection pulleys 13 and the load carrier 4 with the actual course of the ropes 6a-d in this figure.

[0109] Fig. 9 Figure 1 shows a further modification of the load transport device 1, in which a feedforward control 38 is provided in the rope length controller 22. The provision of the feedforward control 38 improves the performance and stability of the rope length control, a well-known principle in control engineering. Apart from this, the control device 20 is identical to the illustration shown in Figure 2. Fig. 6 .

[0110] In the Fig. 10a bis 10e The process of picking up a load 3 is shown schematically to further explain the functioning of the rope length control 22 during the operation of the load transport device 1. Fig. 10a bis 10e Figure 1 shows a highly simplified load transport device 1 in a two-dimensional representation, in which only two positioning cables 6a and 6b, and a lifting cable 10 are shown. For the sake of simplicity, the lifting cable 10 is only shown between the load carrier 4 and the load-handling device 5.

[0111] The Fig. 11 shows a schematic diagram of the progression of the actual rope lengths of the positioning ropes 6a and 6b and the actual rope length of the lifting rope 10 in the five steps a to e according to the Fig. 10a bis 10e The steps shown are as follows. The actual rope length 50 of the positioning rope 6a is shown with a solid line, and the actual rope length 51 of the positioning rope 6b is shown with a dashed line. The actual rope length 52 of the lifting rope 10 is shown with a dashed line. The lines between points a to e serve only to improve the readability of the different actual rope lengths.

[0112] Fig. 12 shows a diagram of the course of the rope forces in the positioning ropes 6a and 6b and the lifting rope 10 in the five steps a to e according to Fig. 10a bis 10e The rope force 53 of the positioning rope 6a is shown with solid lines, the rope force 54 of the positioning rope 6b with dashed lines, and the rope force 55 with dash-dotted lines. The lines between points a to e serve only to improve the readability of the different rope forces.

[0113] Fig. 10a Figure 5 now shows a situation in which the load-bearing device 5 is located above the load 3. That is, the load-bearing device 5 and the load-bearing support 4 are located vertically above the load 3, as illustrated by the vertical line 56. .

[0114] In Fig. 10b The actual rope length of 52 of the hoist rope is 10 compared to Fig. 10a extended so that the load-bearing device 5 is located just above the load 3. The position of the load carrier 4 is opposite Fig. 10a unchanged, i.e., the actual rope lengths 50, 51 are the same as before. Fig. 10a unchanged, see point b in Fig. 11 The rope forces 53, 54, 55 remain essentially constant, see point b in Fig. 12 .

[0115] In the Fig. 10c In the depicted situation, the load carrier 5 is placed on the load 3, so that the positioning ropes 6a, 6b are in comparison to the Fig. 10a und 10b sags slightly more and the lifting rope 10 is relieved of tension, cf. the rope forces in Fig. 12 at point c . To ensure that the load carrier 4 remains vertically above the load-bearing device 5, the actual rope lengths of the positioning ropes 6a, 6b are slightly extended relative to point b, see also Fig. 11 .

[0116] Fig. 10d Figure 1 shows a situation where the load 3 has just been lifted from the base 14. It is evident that the positioning cables 6a and 6b are under considerable tension and the actual cable lengths 50 and 51 are relative to the reference point. Fig. 10c are shortened, while the lifting rope 10 has the same length as in Fig. 10c as shown, see also Fig. 11 This means that until the load 3 is lifted from the base 14, the rope length control 22 is achieved solely by changing the actual rope lengths 50, 51 of the positioning ropes 6a, 6b. In other words, during the lifting process of a load 3 still resting on the base 14, the load measuring device 21 increases the load measurement value by tightening the positioning ropes 6a, 6b. This allows the interpolator 32 to determine new target rope lengths for the positioning ropes 6a and 6b, and the rope length control 22 adjusts the actual rope lengths 50, 51 to these target lengths. The distance between the load-handling device 5 and the load carrier 4 in the vertical direction remains constant due to the unchanging length of the lifting rope 10.This ensures that the load carrier 4 remains vertically positioned above the load 3 or the load-bearing device 5 until the load 3 is lifted. This prevents the load 3 from pivoting at the moment it is lifted from the base 14.

[0117] In Fig. 10e The load 3 is lifted even further from the ground 14, with only the lifting cable 10 now differing from the situation in Fig. 10d is shortened. The rope forces 53-55 remain compared to the in Fig. 10d The situation shown remains essentially constant, cf. Fig. 12 .

[0118] By measuring the weight of the load 3, the rope length control 22 makes it possible to adjust the actual rope lengths of the positioning ropes 6a-d and the lifting rope 10 depending on the measured load. This is described in the Fig. 10a bis 10e This is evident from the fact that the load carrier 4, the load-bearing device 5, and the load 3 always remain on the vertical 56. If no rope length control 22 is carried out in this manner, the asymmetrical distribution of the actual rope lengths of the positioning ropes 6a and 6b would cause the load 3 to swing upwards in the horizontal direction when lifted.

[0119] In the inventive method, the actual rope length of the positioning ropes 6a and 6b and the lifting rope 10 can be readjusted by querying new target rope lengths for the positioning ropes 6a, 6b and the lifting rope 10 in the database 23 for the target point to be set, so that the load 3 is reliably lifted in the vertical direction. The inventive method ensures in a simple manner that when the load 3 is lifted from the surface 14, neither the load 3 nor the load-bearing device 5 swings upwards relative to the load carrier 4. This is particularly advantageous when transporting the load 3 over uneven terrain or when maneuvering around obstacles, in order to prevent collisions.

[0120] Even when picking up bulk material using a load-handling device with a scraper bucket, continuous measurement of the load's weight can be used. d.h. The system reacts to changes in load measurements by adjusting the actual rope lengths based on the currently received quantity or mass of bulk material, for example, to prevent impermissible sagging of one or more positioning ropes during material handling. A similar principle applies when emptying or unloading the scraper bucket or any other grab attached to the load-handling device. z.B. of a bulk material grab, in order to prevent a horizontal displacement of the load carrier or the load-handling device during partial or complete unloading of the load by means of a readjustment of the actual rope lengths of the positioning ropes when the load measured at the load-handling device changes (by unloading bulk material etc.).

[0121] The method according to the invention can also be applied to a load transport device 1 in which the distance of the load-handling device 5 to the load carrier 4 is always constant, i.e., if, compared to the previously described embodiment, a lifting cable 10 and the associated possibility of a load-handling device 5 that can be raised and lowered relative to the load carrier 4 are omitted. In other words, the Fig. 1 The load transport device 1 shown is designed such that the load-handling device 5, which is designed as a hook, hangs from the load carrier 4 at a fixed distance. This means that, in this variant, all movements of the load carrier 4 and the load-handling device 5 attached to it within the workspace 2 are achieved by changing the actual lengths of the positioning cables 6a-d. As already mentioned, the load-handling device 5 could also be attached directly to the load carrier 4.

[0122] Unlike the depictions in the Figuren 2 bis 4 A lifting winch 11 can then be dispensed with, so that even the in Fig. 5 The indicated rope length control 22 of the lifting rope 10 is omitted. The remaining structure according to Fig. 5 Regarding the rope length control 22 of the positioning ropes 6a-6d, it remains unchanged, except that a pre-calculation of pre-calculated target rope lengths of the lifting rope 10 is omitted. That is, the representations according to Fig. 6 bis 9 This also applies to the embodiment variant in which the distance of the load-bearing device 5 from the load carrier 4 is constant and the rope length control 22 is carried out exclusively with regard to the positioning ropes 6a-d analogously to the previously explained embodiment.

[0123] The process of lifting a load 3 from the ground 14 can also be carried out without the lifting rope 10. Fig. 10b bis 10d can be taken from the fact that in the situations depicted in these figures, the lifting cable 10 has a constant length. The in Fig. 11 The actual rope length 52 of the lifting rope 10 shown and the course of the rope force 55 of the lifting rope 10 can therefore be ignored.

[0124] In Fig. 10b The load-bearing device 5 is positioned just above the load 3. The load-bearing support 4 is located vertically above the load-bearing device 5. .

[0125] In the Fig. 10c In the depicted situation, the load carrier 5 is positioned on the load 3 by a slackening of the positioning ropes 6a, 6b, such that the positioning ropes 6a, 6b are in a different position compared to the Fig. 10b sag somewhat more, cf. rope forces 53, 54 in Fig. 12 at point c .

[0126] Fig. 10d Figure 1 shows the situation where load 3 has just been lifted from the base 14. It is evident that the positioning cables 6a and 6b are under considerable tension and the actual cable lengths 50 and 51 are different from the reference length. Fig. 10c are shortened. During the lifting process of a load 3 still resting on the base 14, the load measuring device 21 increases the load measurement value by tensioning the positioning cables 6a, 6b. This allows the interpolator 32 to determine new target cable lengths for the positioning cables 6a and 6b, and the cable length control 22 adjusts the actual cable lengths 50, 51 to the target cable lengths of the positioning cables 6a, 6b. This ensures that the load carrier 4 remains vertically above the load 3 or the load-bearing device 5 until the load 3 is lifted. This prevents the load 3 from pivoting at the moment it is lifted from the base 14.

[0127] In this version, as mentioned, the further transport of the load 3 in the working area 2 is carried out exclusively via control of the positioning winches 7. Legende Regarding the reference numbers:

[0128] 1 Load transport device 2 Work area 3 Load 4 Load carrier 5 Load handling device 6a Positioning rope 6b Positioning rope 6c Positioning rope 6d Positioning rope 7 Positioning winch 8 Positioning winch drive 9 Suspension device 10 Lifting rope 11 Lifting winch 12 Lifting winch drive 13 Deflection pulley 14 Ground 20 Control unit 21 Load measuring unit 22 Rope length control 23 Database 24 Data processing unit 25 Absolute encoder 26 Input unit 27 Path planning interface 28 Target coordinate conversion unit 29 Design parameters 30 Indirect kinematics model 31 Meshing algorithm 32 Interpolator 33 Frequency converter 34 Optimizer 35 Optimization conditions 37 Target data 38 Feedforward control 39 Controller module 40 Controlled system 41 Data query unit 50 Actual rope length 51 Actual rope length 52 Actual rope length 53 Rope force 54 Rope force 55 Rope force 56 Vertical

Claims

1. A method for closed-loop control of a movement of a load (3) in a working space (2) of a load transport means (1) by means of a control means (20) of the load transport means (1), wherein the load transport means (1) has a load carrier (4) and at least one load pickup device (5) which is fastened to the load carrier (4) for picking up the load (3), and at least three positioning cables (6a, 6b, 6c, 6d) and at least three suspension devices (9) arranged spaced apart from each other, wherein each suspension device (9) has at least one positioning cable winch (7) for winding and unwinding one of the positioning cables (6a, 6b, 6c, 6d), and the load carrier (4) is suspended from the suspension devices (9) by means of the positioning cables (6a, 6b, 6c, 6d), wherein the load carrier (4) and the load pickup device (5) which is fastened thereto are displaceable in and / or over the working space (2) by actuating the positioning cable winches (7), the method comprising the following steps: - acquiring target coordinates, which are currently to be set, of a target point in the working space (2) towards which the load pickup device (5) is to be moved; - determining a load measured value by measuring the weight of the load (3) picked up on the load pickup device (5) by means of a load measurement means (21) of the load transport means (1); - determining the actual cable lengths of the positioning cables (6a, 6b, 6c, 6d); - ascertaining the desired cable lengths of the positioning cables (6a, 6b, 6c, 6d) which are to be set by the respective positioning cable winch (7) by winding or unwinding for the target coordinates of the target point which are currently to be set, and for the current load measured value; - adapting the actual cable lengths of the respective positioning cables (6a, 6b, 6c, 6d) to the desired cable lengths of the respective positioning cables (6a, 6b, 6c, 6d) which are to be set by actuating the respective positioning cable winch (7) by means of a cable-length regulation means (22) of the control means (20) and winding or unwinding the respective positioning cables (6a, 6b, 6c, 6d); characterised in that the control means (20) has a database (23) in which a large number of data sets are stored, with a pre-calculated desired cable length being stored in each data set for predefined target coordinates of a predefined target point and for a predefined load value for one of the positioning cables (6a, 6b, 6c, 6d) in each case, and the desired cable lengths of the positioning cables (6a, 6b, 6c, 6d) which are to be set by the respective positioning cable winch (7) are ascertained by the control means (20) by querying the database (23) in that for each of the positioning cables (6a, 6b, 6c, 6d) at least one data set matching the target coordinates of the target point which are currently to be set and the current load measured value is searched in the database (23) by the control means (20), and the desired cable length of the respective positioning cable (6a, 6b, 6c, 6d) which is to be set is determined on the basis of the pre-calculated desired cable length of the at least one matching data set.

2. A method according to claim 1, characterised in that the target coordinates which are currently to be set are calculated by means of a target-coordinate conversion unit (28) of the control means (20) from a predefined velocity vector issued by a movement-prescribing means of the load transport means (1).

3. A method according to claim 1 or 2, characterised in that for each of the positioning cables (6a, 6b, 6c, 6d) at least two data sets which are closest to the target coordinates of the target point which are currently to be set and to the current load measured value are searched in the database (23) by the control means (20), and the desired cable length of the respective positioning cable (6a, 6b, 6c, 6d) which is to be set is determined by interpolation on the basis of the pre-calculated desired cable lengths of the at least two closest data sets.

4. A method according to one of claims 1 to 3, characterised in that the cable-length regulation means (22) has a pilot control (38) for the desired cable length of the positioning cables (6a, 6b, 6c, 6d) which is to be set.

5. A method according to one of claims 1 to 4, characterised in that the precalculation of the pre-calculated desired cable lengths of the positioning cables (6a, 6b, 6c, 6d) is carried out in a data-processing step of the method in a data-processing means (24), separate from the control means (20), of the load transport means (1), with a model of the indirect kinematics (30) of the load transport means (1) and an optimiser (34) being stored in the data-processing means (24), and the model of the indirect kinematics (30) and the predefined load values and also the predefined target coordinates of the predefined target points being supplied to the optimiser (34), and valid solutions for the desired cable lengths of the positioning cables (6a, 6b, 6c, 6d) being ascertained by the optimiser (34) by means of the model of the indirect kinematics (30) for the predefined load values at the predefined target coordinates, and the valid solutions as the pre-calculated desired cable lengths of the positioning cables (6a, 6b, 6c, 6d), together with the load value associated in each case and the predefined target coordinates associated in each case, being stored by the data-processing means (24) as one of the data sets in the database (23) of the control means (20).

6. A method according to claim 5, characterised in that in the data-processing step the specific cable weight of the respective positioning cable (6a, 6b, 6c, 6d) is taken into account in pre-calculating the pre-calculated desired cable lengths of the positioning cables (6a, 6b, 6c, 6d) in the model of the indirect kinematics (30).

7. A method according to claim 5 or 6, characterised in that the data-processing step is based on at least one optimisation condition from among: - lowest sag of the positioning cables (6a, 6b, 6c, 6d); - lowest cable force of the positioning cables (6a, 6b, 6c, 6d); - lowest sum of the cable forces of the positioning cables (6a, 6b, 6c, 6d); - highest permissible cable force of the respective positioning cable (6a, 6b, 6c, 6d); - smallest difference between the cable forces of the positioning cables (6a, 6b, 6c, 6d); - elastic deformation of the suspension devices (9).

8. A method according to one of claims 5 to 7, characterised in that in the data-processing step a meshing algorithm is applied which meshes the predefined target coordinates to form a computational mesh, in particular a polygonal mesh, as computational-mesh data, the computational-mesh data comprising linking data for linking adjacent ones of the predefined target coordinates of the predefined target point of the load pickup device (5) and adjacent ones of the predefined load values, and the computational-mesh data being stored in the database (23) of the control means (20), and the computational-mesh data being taken into account by the control means (20) in determining the desired cable length of the respective positioning cable (6a, 6b, 6c, 6d) which is to be set.

9. A method according to claim 8, characterised in that the data-processing step comprises an iteration for compressing the computational mesh in at least one edge region of the working space (2), with desired cable lengths of the positioning cables (6a, 6b, 6c, 6d) being ascertained for additional coordinates of additional positions of the load pickup device (5) in the edge region.

10. A method according to one of claims 5 to 9, characterised in that the method comprises a step of acquiring design parameters (29) for calculating the pre-calculated desired cable lengths of the positioning cables (6a, 6b, 6c, 6d) in the data-processing step, the design parameters (29) comprising at least one of the following characteristic values: - the position of cable run-off points of the suspension devices (9) at which the respective positioning cable (6a, 6b, 6c, 6d) runs off from the respective suspension device (9) in a direction towards the load carrier (4); - the positions of the positioning cable winches (7); - the specific cable elongation of the respective positioning cable (6a, 6b, 6c, 6d); - the rigidity of the respective suspension device (9); - the weight of the load carrier (4); - the weight of the load pickup device (5); - the centre of mass of the load carrier (4) and / or of the load pickup device (5).