EP4186848A1 - Trajectory planning with flexible obstacle planning functionality - Google Patents

Abstract

A method for controlling a lifting device (1) which is improved compared to the prior art and which moves a load (8) along a first direction of movement (X) and along a second direction of movement (Y) within a predetermined working area (15) of the lifting device (1). moved from a starting point (A) to an end point (E), individual movements (TE _X , TE Y ) are planned for the first direction of movement (X) and for the second direction of movement ( _Y ), by means of which the load (8) under Avoiding a collision with a changed or newly specified obstacle (11) is moved on.

Description

The present invention relates to a method for controlling a lifting device that moves a load along a first direction of movement and along a second direction of movement within a predetermined working range of the lifting device according to a predetermined trajectory from a starting point to an end point.

The planning of suitable trajectories is often an essential part of operational and problem-solving concepts in a wide variety of technical applications. A trajectory is to be understood as the temporal progression of the movement of a body along a trajectory, a path or a path, which in the case of a rigid Body can be described, for example, by the course of the position of its center of gravity. The usual use of the term "trajectory" in control engineering as a time (setpoint) course of state or output variables of a (technical) system to be controlled deviates from this definition, but does not represent a contradiction to it. Requires a technical problem on the one hand the planning of a movement of a physical body, but on the other hand also the implementation of the planned movement, for example through a suitable regulation or (control) of drive elements provided for this purpose, the meanings of the term "trajectory" mentioned coincide, what in many applications and is also the case in the context of the following explanations.

A trajectory planning corresponding to the above explanations represents a basic subtask in the automation of vehicles, such as passenger cars or trucks. With the help of map or sensor-based data, trajectories, which primarily describe the movement of a vehicle on a road, are initially planned in many cases and then implemented as target values by the regulation/control of the vehicle. When implementing this procedure, in addition to comfort aspects, the feasibility and freedom from collisions of a trajectory are often important criteria.

Another area in which the topic of trajectory planning is of great importance is the field of transport logistics. In order to increase the profitability of logistics processes, among other things, rapid goods handling is required in this sector. This results in particular in demands for rapid loading and unloading of cargo ships, and for correspondingly rapid movements of lifting devices used for loading and unloading. Such lifting devices are also increasingly operated in an automated manner, with demands for rapid movement processes being directly reflected in the trajectories to be implemented in (automated) operation.

Lifting devices are available in a wide variety of designs, which are used accordingly in a wide variety of applications. There are tower cranes, which are mainly used for structural and civil engineering, or mobile cranes, e.g. for the assembly of wind turbines. Overhead cranes are also used, for example, as indoor cranes in factory buildings, or gantry cranes, for example, for the manipulation of transport containers at transhipment points for intermodal goods handling. Goods to be transported are mainly stored in standardized containers, so-called ISO containers, which are equally suitable for road, rail and water transport modes. Objects to be transported by a lifting device, such as a combination of containers with goods contained therein, are referred to below in particular simply as "load" or "loads".

The structure and operation of gantry cranes in particular is well known and, for example, in the US 2007/0289931 A1 described using a "Ship-to-Shore Crane" (STS Crane). A gantry crane has a supporting structure or a gantry on which a boom is arranged. The portal with wheels is movably arranged on a track, for example, and can be moved in one direction. The boom is firmly connected to the portal and usually has a trolley that can be moved along the boom. To pick up a load, such as an ISO container, the trolley is usually connected to a load-carrying element, a so-called spreader, by means of four cables. To pick up and manipulate a container, the spreader can be raised or lowered using cable winches. The spreader can also be adapted to containers of different sizes.

Typically, cranes are operated by a crane operator, who usually controls the movement of a crane from a cab. Such a cabin can be arranged on a portal or on a movable trolley. For a precise and collision-free manipulation of loads, high demands are placed on the crane driver, which is why at least one year of training or induction is usually necessary. In particular, the rapid movement of loads with small pendulum movements is a highly complex activity, which is why several years of practical experience are usually required for the successful exercise of the activity of a crane operator. The work of a crane driver is often made more difficult by the high physical strain, among other things due to the high level of concentration required in connection with long periods of sitting with a downward gaze. For these reasons, among others, it is a declared goal of automation technology to at least partially automate the complex manipulation processes of a lifting device and thus simplify it for the crane operator. Inseparably connected with the automated operation of lifting devices is the Planning of suitable trajectories to be implemented by the lifting devices in automated operation.

In this context, a question that has so far received little attention but is becoming increasingly important concerns the replanning of existing trajectories. An example relevant to practice, in which the need to replan the trajectory occurs more frequently, is the already mentioned STS ("Ship-to-Shore") cranes. As mentioned, the primary purpose of STS cranes is to offload containers from cargo ships onto trucks or so-called "Automated Guided Vehicles" for onward transport. It is often the case that a truck has not yet arrived in an area that can be reached by the lifting device or crane, but the movement of the load has to be started for reasons of efficiency. For obvious reasons, the actual position of a load-carrying truck can only be recorded after it has arrived and subsequently taken into account. In order to be able to start the movement of a container or a load before the truck arrives, it is necessary in such cases to first assume a suitable target position for planning a first trajectory and later adjust the assumed target position to the true target position as part of a replanning to adjust.

The same applies to obstacles that must be avoided by the load during the movement of the load. An obstacle can be another ship, a stack of containers, for example on a ship or on land, or some other obstacle. In this regard, for reasons of efficiency, it can be advantageous to start moving a container or a load before the dimensions of an obstacle are known, for example. Also, an obstacle can only appear during the movement of a load. In such cases, it is also necessary to make initial assumptions, particularly with regard to the number and shape of obstacles to be taken into account. On the basis of these assumptions, a first trajectory can be planned, which has to be adapted to the actual obstacles as part of a later replanning. It is therefore necessary to replan a trajectory depending on changed obstacles.

Although the topic of trajectory planning for lifting devices is dealt with in the prior art, questions regarding trajectory replanning, in particular due to changing obstacles, have so far hardly been mentioned in the relevant literature.

That's how she describes it EP 3461783 B1 the determination of a trajectory for the movement of a load by a lifting device. For this purpose, a geometric path is calculated on the one hand, and a dynamic path on the other hand, which are combined in a further step to generate a trajectory. A downside to this approach is the one with her associated large computational effort. A (real-time) replanning during the operation of a lifting device is therefore only possible to a limited extent.

The CN 111170153A describes, in contrast, a method for replanning a given trajectory on the basis of obstacles detected by measurement. The necessary metrological requirements represent a significant complication for the implementation of this method CN 111170153A does not state how obstacles that have changed during operation can be taken into account, and moreover makes no statements about the real-time capability of the method described.

In addition, the known state of the art shows a large number of other disadvantages, such as the usually given requirement that no changes in direction along the specified directions of movement may result from a replanning. Another essential point is the real-time capability of concepts for trajectory replanning. Since the replanning described usually has to be carried out during the operation of a lifting device, the computing effort associated with a replanning must not impair the operation of a lifting device. This aspect is also not considered in the prior art.

It is therefore an object of the present invention to specify an improved method for replanning the trajectory for a lifting device, which method enables a trajectory along which a load is moved to be replanned efficiently, taking into account a variable obstacle.

This object is achieved by the present invention. The starting point here is a lifting device which moves a load along a first direction of movement and along a second direction of movement within a predefined working area of the lifting device according to a predefined trajectory from a starting point to an end point.

According to the invention, a new obstacle to the movement of the load, which is located between the position assumed by the load at the time of the command and the end point, is specified for this lifting device at a command time during the movement of the load and/or an existing obstacle which is between the command time from the position assumed by the load and the end point, changed to a new obstacle for the movement of the load, taking into account predetermined kinematic restrictions of the lifting device for the first direction of movement and for the second direction of movement, at least one individual movement is planned, which further movement of the load along the respective direction of movement from the command time determines, with each In the direction of movement, at least one individual movement ends in a projection of the end point onto the respective direction of movement, and the planned individual movements are carried out according to a predetermined sequence of movements in order to move the load without colliding with the obstacle along the first direction of movement and along the second direction of movement according to a sequence of movements the replanning trajectory resulting from the planned individual movements. By planning individual movements, the numerical complexity is significantly reduced in comparison to methods known from the prior art, as a result of which efficient and flexible replanning becomes possible even during operation of a lifting device.

In an advantageous manner, the individual movements planned for the first direction of movement and for the second direction of movement are planned as individual movements that are independent of one another, which means that no mutual dependencies have to be taken into account and the actual replanning task can be simplified even further.

In a further advantageous embodiment of the present invention, the position profiles of the load specified by the planned individual movements are specified as position profiles that can be continuously differentiated at least four times over time. As a result, vibrations in the moving load can be avoided in a remarkable way.

In a further advantageous embodiment of the present invention, the position curves specified by the individual movements are filtered by means of a filter with a specified time constant in order to generate the time-based at least quadruple continuous differentiability. As a result, it can be ensured in a particularly advantageous manner that specified kinematic limitations of the lifting device are complied with. In this case, the time constant of the filter can advantageously be made dependent on the geometry of the lifting device in order to enable precise adjustment to the given lifting device.

In a further advantageous embodiment of the present invention, a second individual movement is planned for the second movement direction in order to move the load around the newly specified and/or changed obstacle. It should be noted here that, in order to bypass an obstacle, it is usually necessary to combine the individual movement planned for bypassing with other individual movements planned along the other movement directions, ie to combine horizontal and vertical movements with one another in a suitable manner. In this case, it may be necessary to coordinate or adapt the new individual movement to any other individual movements that may already exist. In the manner described, the load can be Obstacle can be moved and collisions of the load with the given obstacle can be avoided.

In a further advantageous embodiment of the present invention, the sequence of movements mentioned provides for an alternating start and, if necessary, an overlapping execution of the planned individual movements along the first direction of movement and of individual movements along the second direction of movement, which means that obstacles can be avoided on the one hand, and on the other hand to a sometimes significant degree time can be saved.

Furthermore, the method according to the invention allows, before at least one planned individual movement is carried out, to check whether the replanning trajectory to be expected will lead to a collision of the load with an obstacle specified in the work area. This check can be carried out in an advantageous manner by comparing the collision times at which the respective individual movements reach projections onto the corresponding direction of movement of a support point derived from the specified obstacle, with the determination of these collision times at which the respective individual movements projections onto the corresponding Reach the direction of movement of a base point derived from the given obstacle, a numerical method for zero point search can be used. In this way, obstacles in the working area of the lifting device can be included in the replanning according to the invention, and possible collisions can be reacted to in good time. It should be noted here that the procedure according to the invention allows the described check to be carried out in a particularly efficient manner.

If a possible collision is detected by the advance calculation described, at least one individual movement cannot be carried out and instead a specified braking process can be carried out along the direction of movement for which the at least one individual movement which was not carried out was planned, for at least the duration of a specified minimum braking time. In this way, on the one hand, collisions can be avoided in an advantageous manner, and on the other hand, a new initial situation is created in the manner described, from which a new replanning of individual movements is made possible.

In accordance with the above statements, a new individual movement can be planned in an advantageous manner instead of the at least one individual movement that was not carried out for the corresponding direction of movement, with a replanning trajectory to be expected from the at least one new individual movement being determined and it being checked whether the replanning trajectory to be expected leads to a collision of the load with an obstacle specified in the working area, and wherein the new individual movement is executed if no collision is detected, or the specified braking process is continued for at least one additional minimum braking time and a new planning of a single movement as well as a review of the replanning trajectory, which is carried out by the newly planned Individual movement is to be expected, is carried out if another collision with an obstacle is detected. In this way, the method according to the invention can be continued without a collision, even if a first replanning would have led to a collision, and it can be ensured that the transported load does not collide with obstacles during the entire movement of the load.

Furthermore, to support the present invention, the position of the load can be measured using measurement technology and the measurement of the position of the load can be used when carrying out the individual movements. The use of measurement data is usually particularly advantageous, particularly in the control-technical implementation of planned individual movements.

It should also be pointed out that the method according to the invention is in no way limited to movements in the plane, and that movements in (three-dimensional) space can also be planned using the present invention. In the case of more than two dimensions, the properties of the subject inventions are even more advantageous. The independence of the planned individual movements should be particularly emphasized, especially since three mutually dependent coordinates would further increase the complexity to be managed in a replanning - compared to the already challenging 2D case.

• Fig. 1 eine schematische Darstellung eines Containerkrans mit einer Trajektorie innerhalb eines Arbeitsbereichs des Containerkrans,
• Fig. 2a einen möglichen Ablauf des erfindungsgemäßen Verfahrens bei Vorgabe eines geänderten Hindernisses,
• Fig. 2b eine Einzelbewegung in X-Richtung,
• Fig. 2c eine Einzelbewegung in Y-Richtung,
• Fig. 2d eine weitere Einzelbewegung in Y-Richtung,
• Fig. 3a eine zeitoptimale Einzelbewegung für eine Bewegungsrichtung,
• Fig. 3b ein Blockschaltbild zur Filterung der zu einer Einzelbewegung gehörenden Positions-, Geschwindigkeits- und Beschleunigungsverläufe,
• Fig. 4 eine Trajektorie und eine Umplanungstrajektorie innerhalb eines Arbeitsbereichs mit einer Verbotszone,
• Fig. 5a Einzelbewegungen in X-Richtung bei Durchführung eines erfindungsgemäßen Bremsvorganges,
• Fig. 5b Einzelbewegungen in Y-Richtung bei Durchführung eines erfindungsgemäßen Bremsvorganges,
• Fig. 5c resultierende Trajektorien bei Durchführung eines erfindungsgemäßen Bremsvorganges,
• Fig. 6 eine Umplanungstrajektorie zur Kollisionsvermeidung bei zwei Hindernissen.

The present invention is described below with reference to the Figures 1 to 6 explained in more detail, which show exemplary, schematic and non-limiting advantageous embodiments of the invention. while showing

• 1 a schematic representation of a container crane with a trajectory within a working area of the container crane,
• Figure 2a a possible course of the method according to the invention when specifying a changed obstacle,
• Figure 2b a single movement in the X-direction,
• Figure 2c a single movement in the Y direction,
• Fig. 2d another single movement in the Y-direction,
• Figure 3a a time-optimal individual movement for one direction of movement,
• Figure 3b a block diagram for filtering the position, speed and acceleration curves associated with a single movement,
• 4 a trajectory and a replanning trajectory within a work area with a no-go zone,
• Figure 5a Individual movements in the X-direction when carrying out a braking process according to the invention,
• Figure 5b Individual movements in the Y-direction when performing a braking process according to the invention,
• Figure 5c resulting trajectories when performing a braking process according to the invention,
• 6 a replanning trajectory to avoid collisions with two obstacles.

Fig.1 shows a lifting device 1 in the form of a schematic container crane 2, as used for loading and unloading ships in a port. A container crane 2 usually has a supporting structure 3 which is either fixed or movable on the ground. In the case of a movable arrangement, the supporting structure 3 can be arranged on rails such that it can move in the Z direction, for example. Due to this degree of freedom in the Z-direction, the container crane 2 can be used flexibly in terms of location. To move the supporting structure 3 in the Z-direction, for example, a suitable displacement device can be arranged on the lifting device, for example driven wheels, a cable pull, a toothed drive or the like. The supporting structure 3 has a cantilever 4 which is firmly connected to the supporting structure 3 at a specific height y _T .

A running element 5 is usually arranged on this boom 4, which is movable in the longitudinal direction of the boom 4, in the example shown in the X-direction. Accordingly, a running element 5 can be mounted in guides by means of rollers. A running element drive, not shown, is provided for the running element 5 in order to move the running element 5 in the X-direction. The running element drive can be provided on the running element 5 itself, but can also be arranged on the boom 4 or on the supporting structure 3 . The running element 5 is usually connected to a load bearing element 7 for bearing a load 8 with the aid of holding elements 6 . In the case of a container crane 2, the load 8 is typically a container 9, in most cases an ISO container, 20, 40 or 45 feet long, 8 feet wide and 8 feet 6 inches high.

The holding elements 6 are usually designed as ropes, with four holding elements 6 being arranged on the running element 5 in most cases, but more or fewer holding elements 6 can also be provided, in the simplest case just a single one Retaining element 6. To accommodate a load 8, such as a container 9, the distance between the running element 5 and the load-carrying element 7 can be adjusted using a lifting drive (not shown), in 1 accordingly in the Y-direction. If the holding elements 6 are designed as cables, the lifting height is usually adjusted by means of one or more cable winches. The area in which a lifting device 1 can move a load 8 is referred to as the working area 15 in the present context. Depending on the size and structural design of the lifting device 1, the working area 15 can vary.

in the in 1 In the situation shown, the aim is to move the load 8 from the starting point A to the end point E. When loading a ship, the starting point A can be, for example, a position of a container 9 on land, such as on a truck trailer, rail car or storage yard, and the end point E can be, for example, a predetermined position of the container 9 on a ship. In an advantageous manner, the working area 15 can be defined in one plane or in the entire movement space and it can be checked whether a specified starting point A and a specified end point E are within the working area 15 and whether a continuous movement of the load 8 from Starting point A to end point E is possible.

In order to move a load 8 along a trajectory T from the starting point A to the end point E, the lifting device 1 has a crane control 16 with a computing unit 12, e.g. in the form of an electronic control unit in the form of suitable hardware and/or software, by means of which the movement the load 8 can be controlled along the respective direction of movement X, Y, Z. If a starting point A and/or ending point E is defined manually by a user, for example, the starting point A and/or ending point E can be transmitted to the processing unit 12, e.g. via a suitable interface. A starting point A and/or an end point E can also be determined in the computing unit 12 . Possible implementations of a computing unit 12 include microprocessor-based hardware, microcontrollers and integrated circuits (ASIC, FPGA). To control and/or regulate the movement of the load 8, the crane controller 16 communicates with the drives provided for this purpose, such as a running element drive or a cable winch, and is usually designed in such a way that it transmits the current position of the running element 5, the position of the load receiving element 7 and can optionally also detect the position of the supporting structure 3 by measurement.

In this sense, in the in 1 In the situation shown, the coordinates of the central point Pz, which is arranged on the upper side of the load-carrying element 7 facing the boom 4, can be detected in the XY plane E _XY using the coordinates x _L and y _L of the load-carrying element 7, but the coordinates x _T and y _T of the running element 5 are detected in the X and Y directions. The central point Pz can here be used to describe the position of the load 8, and accordingly can also be considered as a load position. Furthermore, the position y _T of the running element in the Y-direction is often determined by the structural height of the supporting structure 3 or the cantilever 4 and is therefore constant. The coordinates are related to a given coordinate system. When the load 8 moves in the Z direction, i.e. when the supporting structure 3 of the lifting device 1 moves in the Z direction, the position z _L of the load bearing element 7 and the position z _T of the running element 5 in the Z direction would also be detected .

Fig.1 12 also shows an obstacle 11 located between the starting point A and the end point E. An obstacle 11 can be another ship, a stack of containers 9 or another obstacle 11. The obstacle 11 means that no direct connection between the starting point A and the end point E, ie no trajectory T in the form of a straight line, is possible. In order to avoid collisions or to ensure a sufficient safety distance, the load 8 must avoid the specified obstacles 11 during its movement. In an advantageous manner, obstacles 11 can be taken into account by so-called forbidden zones V _i (the index i≧1 relates to the number of forbidden zones V _i ), the forbidden zones V _i enclosing the obstacles 11 . A prohibited zone V _i can therefore also be noticeably larger than an obstacle 11 it encompasses. A prohibited zone can be defined manually by a user, for example via a suitable interface in the processing unit 12 , or it can be determined automatically by the processing unit 12 . A suitable laser scanning method can be used for this purpose, for example, which scans a working area 15 of the lifting device 1 and thereby detects and measures obstacles 11 and forwards the data determined to the computing unit 12 . Such methods are known in the art.

A rapid transfer of the load 8 from the starting point A to the end point E is usually required from a trajectory T, along which the load 8 is moved. As stated at the outset, during such a transfer it may be necessary for a number of reasons to adapt a specified trajectory T during the movement of the load 8 to changed circumstances in the area of the lifting device 1, ie to replan the trajectory T. This problem is solved by the method according to the invention. FIGS Figures 2a-2d concretely shown.

Three situations are plotted on the time axis t that can occur when using the method according to the invention during the movement of a load 8 by a lifting device 1 along a first and along a second direction of movement, here along the directions of movement X and Y Figure 2a The situation shown begins the movement of the load 8 at the time t _A in the starting point A. The position of the load 8 is thereby equated with the previously mentioned central point Pz and is therefore also denoted by Pz. At time t _A the movement of the load 8 begins along the in Figure 2a predetermined trajectory T shown in dashed lines, the position Pz of the load 8 and the starting point A initially lying one above the other. For the planning of the trajectory T, the obstacle 11a was assumed, from which the forbidden zone V _1a was derived.

At time t _K , also referred to below as command time t _K , a new obstacle 11n is now specified instead of the previous obstacle 11a. The command time t _K can be specified by an operator, such as a crane driver, and can therefore be chosen as freely as possible. However, the command time t _K can also be generated internally in the processing unit 12 . Several consecutive command times t _K for a repeated changing of an obstacle 11 are also conceivable. At the command time t _K the load 8 is at the position P _z (t _K ). According to the invention, once the new obstacle 11n has been specified, the replanning of the movement of the load 8 begins immediately. This is done according to the previous statements using projections of the position P _z (t _K ) assumed by the load 8 at the command time t _K and the end point E on the directions of movement X, Y, as well as using projections of support points S _1n , S _2n , the are derived from the new obstacle 11n, to the directions of movement X, Y. The supporting points S _1n , S _2n are preferably, as shown, corner points of the forbidden zone V _1n . Support points S _1a , S _2a can of course also be specified for the forbidden zone V _1a . As will be shown below, support points such as S _1n , S _2n can be used as intermediate targets, in particular when planning movements along the Y axis, in order to avoid collisions with a forbidden zone V _1n and thus with the obstacle 11 _n .

The projections of the position P _z (t _K ) assumed by the load 8 at the command time t _K , the end point E and the support points S _1n , S _2n onto the X-axis are given as Pz', E', S _1n ' and S _2n ', while the projections onto the Y-axis are denoted Pz", E", S _1n " and S _2n ". According to the invention, the projections Pz', E', _S1n ', _S2n ' and the projections Pz", E", _S1n ", _S2n " are considered separately from one another. Individual movements TE are planned for each of these groups of projections in order to move the respective projections Pz′, E′, S _1n ′, S _2n ′ or Pz", E", S _1n ", S _2n " along the corresponding direction of movement X, Y together. A single movement TE preferably defines a position, speed and acceleration profile along the respective direction of movement. For example, the projections Pz′, E′, S _1n ′, S _2n ′ along the direction of movement X are connected by a single movement TEx for the direction of movement X. For each of the directions of movement X, Y, there is initially at least one individual movement TE. Individual movements related to directions of movement such as X, Y are referred to as TEx, TE _Y.

In order to avoid obstacles 11a, 11n, which are arranged between the position P _Z (t _K ) assumed by the load 8 at the command time t _K and the end point E, several individual movements TE _Y can be planned in particular for the second direction of movement Y. Thus, on the one hand, individual movements TE _Y in the form of lifting movements ("hoist up") can be provided for the load 8 along the movement direction Y, and on the other hand, individual movements TE _Y in the form of lowering movements ("hoist down") can be provided. To avoid obstacles 11a, 11n, lifting movements ("Hoist Up") are usually carried out first, and lowering movements ("Hoist Down") are only carried out after a suitable horizontal movement along the X-axis ("Move Trolley") to move the load 8 to move around an obstacle 11n or to lift the load 8 over an obstacle 11n. It should be noted here that in order to move a load 8 around an obstacle 11n, individual movements TE along the movement directions X, Y must be combined.

in the in 2 For the reasons shown, the individual movement TE _Y2 is provided as a lifting process for the load 8, which first lifts the load 8 along the direction of movement Y to such an extent that a collision with the obstacle 11n can be ruled out. In such a scenario, an individual movement TEx along the direction of movement X that has already been planned to transfer the load 8 to the end point E is only started when a collision can be ruled out as described. As mentioned, in order to drive around an obstacle 11, it is usually necessary to suitably combine individual movements TE along the movement directions X, Y. As mentioned, supporting points S _1n , S _2n can be used for planning individual movements TE _Y , TE _Y2 . So can in the in 2 In the situation shown, an individual movement TE _Y2 can first be planned, which connects the projection P _Z "(t _K ) with the projection S _1n ", and a further individual movement TE _Y can be planned, which connects the projection S _2n " with the projection E" connects. Since the projections of the support points S _1n , S _2n on the Y-axis are the same, i.e. S _1n "=S _2n " applies, in the specific case using the two individual movements TE _Y2 , TE _Y in the Y direction in combination with a between the individual movement TEx in the X direction executed in these individual movements TE _Y2 , TE _Y in the Y direction, the obstacle 11n can be bypassed.

In this connection it should be noted that a single single movement TEx along the X-axis from the projection P _Z '(t _K ) to the projection E' is usually sufficient to ensure a collision-free movement of the load 8 to the end point E. It should also be noted at this point that the present invention also covers the case in which an obstacle 11a previously assumed for the planning of a trajectory T later turns out not to be present, ie the obstacle 11a disappears. in one In such a case, a single individual movement TE _Y along the Y-axis is already sufficient to transfer the load 8 from its position P _Z (t _K ) to the end point E.

After the individual movements TE have been planned, the planned individual movements TE are executed in accordance with a predetermined sequence, hereinafter referred to as “movement sequence”, in order to move the load 8 further along the first direction of movement X and along the second direction of movement Y. A replanning trajectory TU thus results from the planned individual movements TE. The replanning trajectory TU is in 2 represented by the solid line.

Individual movements TE, as can occur in the context of the method according to the invention are in the Figures 2b, 2c and 2d shown. According to the Figure 2b shown individual movement TEx, in the framework of which the position profile s _x connects the projection P _Z '(t _k ) with the projections S _1n ', S _2n 'and with the projection E', the planning of an individual movement TE with regard to its temporal position profile s _x for example, by specifying a sigmoid-like curve, which is only to be understood as an example. Other position profiles can also be used at this point.

Figure 2c 12 shows a corresponding individual movement TE _Y2 along the Y-direction, by means of which the projections P _z "(t _k ) and S _1n " onto the Y-direction are connected to one another. The individual movement TE _Y2 accordingly represents a previously described lifting movement and ends at time t _S1 in the projection S _1n ". In Fig. 2d Finally, the individual movement TE _Y is shown, which begins at time t _S2 and which lowers the load 8 starting from the projection S _2n "into the end point E". In this regard, it should be noted that, particularly in the case of lifting movements in the Y direction, it is usually not required that the speed of the load 8 in the Y direction should be equal to zero at the end of the lifting movement. A load 8 is thus lifted above the projections S _1n ″ or S _2n ″, which increases the safety distance from obstacles 11 and is therefore advantageous. As a result, a resulting replanning trajectory TU usually does not go directly through the interpolation points S _1n or S _2n , but runs around them.

By dividing the overall movement to be newly planned into a plurality of individual movements TE to be planned instead, the (re)planning task to be solved is significantly simplified compared to methods known from the prior art. In this way, the complex problem of planning an at least two-dimensional movement is reduced to planning several only one-dimensional movements. It is precisely this fact that proves to be advantageous in practical implementation, since the planning of one-dimensional movements is a problem that is known in control and automation technology and has already been solved in various ways. In the concrete planning of the individual movements TE can be based on a variety of known approaches are used. If, for example, a transfer of the load 8 to the end point E is to be ensured using time-optimized individual movements TE, using the maximum accelerations along the directions of movement X, Y that can be realized by means of the given drives of the lifting device 1, for example the Bang Bang controller approach can be used.

In Figure 3a the planning of a time-optimal individual movement TE for connecting the projections P _Z 'and E' is explained in more detail. In addition to the position curve s _{x ,} the associated speed curve v _x and the associated acceleration curve a _x are also shown along the X axis. The most important dynamic limitation to be taken into account when planning a time-optimal individual movement TE are kinematic limitations of the drives of the lifting device 1, such as a maximum realizable acceleration of the drives or a maximum realizable force by the drives. These kinematic limitations result in limitations for the accelerations of the load 8 that can be realized along the respective directions of movement X, Y. The maximum possible positive acceleration of the load 8 is referred to as a ⁺ _max , the maximum possible negative acceleration of the load 8 as a ⁻ _max . In this sense, the fastest possible individual movement TE along the X-axis is achieved by utilizing the maximum possible positive accelerations a ⁺ _max and the maximum possible negative accelerations a ⁻ _max along the X-axis.

$$\begin{array}{r}{\mathit{v}}_{\mathit{x}}\left(\mathit{t}\right)={\mathit{v}}_{\mathit{x}0}+{\mathit{a}}_{\mathit{max}}^{+}\left(\mathrm{\sigma }\left(\mathit{t}-{\mathit{t}}_{\mathit{k}}\right)-\mathrm{\sigma }\left(\mathit{t}-{\mathit{T}}_{\mathit{a}1}\right)\right)\cdot \left(\mathit{t}-{\mathit{t}}_{\mathit{k}}\right)+{\mathit{a}}_{\mathit{max}}^{+}\cdot \mathrm{\sigma }\left(\mathbf{t}-{\mathbf{T}}_{a1}\right)\cdot \left({\mathit{T}}_{\mathit{a}1}-{\mathit{t}}_{\mathit{k}}\right)\\ +{\mathit{a}}_{\mathit{max}}^{-}\left(\mathrm{\sigma }\left(\mathit{t}-{\mathit{T}}_{\mathit{a}2}\right)-\mathrm{\sigma }\left(\mathit{t}-{\mathit{t}}_{\mathit{E}}\right)\right)\cdot \left(\mathit{t}-{\mathit{T}}_{\mathit{a}2}\right)+{\mathit{a}}_{\mathit{max}}^{-}\left(\mathrm{\sigma }\left(\mathit{t}-{\mathit{t}}_{\mathit{E}}\right)\right)\cdot \left(\mathit{t}-{\mathit{T}}_{\mathit{a}2}\right)\end{array}$$

$$\begin{array}{c}{\mathit{s}}_{\mathit{x}}\left(\mathit{t}\right)={\mathit{P}}_{\mathit{Z}}^{\prime }\left({\mathit{t}}_{\mathit{k}}\right)+{\mathit{v}}_{\mathit{x}0}\mathit{t}+{\mathit{a}}_{\mathit{max}}^{+}\left(\mathrm{\sigma }\left(\mathit{t}-{\mathit{t}}_{\mathit{k}}\right)-\mathrm{\sigma }\left(\mathit{t}-{\mathit{T}}_{\mathit{a}1}\right)\right)\cdot \frac{{\left(\mathit{t}-{\mathit{t}}_{\mathit{k}}\right)}^2}{2}+{\mathit{a}}_{\mathit{max}}^{+}\cdot \mathrm{\sigma }\left(\mathit{t}-{\mathit{T}}_{\mathit{a}1}\right)\\ \cdot \left({\mathit{T}}_{\mathit{a}1}-{\mathit{t}}_{\mathit{k}}\right)\cdot \left(\mathit{t}-{\mathit{T}}_{\mathit{a}1}\right)+{\mathit{a}}_{\mathit{max}}^{-}\left(\mathrm{\sigma }\left(\mathit{t}-{\mathit{T}}_{\mathit{a}2}\right)-\mathrm{\sigma }\left(\mathit{t}-{\mathit{t}}_{\mathit{E}}\right)\right)\cdot \frac{{\left(\mathit{t}-{\mathit{T}}_{\mathit{a}2}\right)}^2}{2}\\ +{\mathit{a}}_{\mathit{max}}^{-}\left(\mathrm{\sigma }\left(\mathit{t}-{\mathit{t}}_{\mathit{E}}\right)\right)\cdot \left({\mathit{T}}_{\mathit{a}2}-{\mathit{t}}_{\mathit{E}}\right)\cdot \left(\mathit{t}-{\mathit{t}}_{\mathit{E}}\right)\end{array}$$

dargestellt werden. Darin steht σ(x) für die aus der Mathematik wohlbekannte Sigma-Funktion, die bei Argumenten größer gleich Null (x ≥ 0) den Wert Eins annimmt, und ansonsten gleich Null ist. v_x0 steht hierbei für die Anfangsgeschwindigkeit zu Beginn der Einzelbewegung. Demnach kann die Planung von Einzelbewegungen TE, anhand derer ein Positionsverlauf s_x, ein Geschwindigkeitsverlauf v_x und ein Beschleunigungsverlauf a_x festgelegt werden, erfolgen, indem wie oben dargestellte Funktionen festgelegt werden, beispielsweise durch die Vorgabe von Zeitpunkten T_a1 und T_a2. In einer vorteilhaften Weise können dazu auch Randbedingungen vorgegeben werden, wie zum Beispiel s_x(t_E) = E', v_x(t_E) = v_tE. Insbesondere die Geschwindigkeit v_tE kann hierbei gleich Null, aber auch verschieden von Null gewählt werden.in Figure 3a example shown, the displayed position, speed and acceleration course can be mathematically as $${\mathit{a}}_{\mathit{x}}\left(\mathit{t}\right)={\mathit{a}}_{\mathit{Max}}^{+}\left(\mathrm{\sigma }\left(\mathbf{t}-{\mathbf{t}}_k\right)-\mathrm{\sigma }\left(\mathbf{t}-{\mathbf{T}}_{a1}\right)\right)+{\mathbf{a}}_{\mathrm{Max}}^{-}\left(\mathrm{\sigma }\left(\mathbf{t}-{\mathbf{T}}_{a2}\right)-\mathrm{\sigma }\left(\mathbf{t}-{\mathbf{t}}_E\right)\right)$$

$$\begin{array}{r}{\mathit{v}}_{\mathit{x}}\left(\mathit{t}\right)={\mathit{v}}_{\mathit{x}0}+{\mathit{a}}_{\mathit{Max}}^{+}\left(\mathrm{\sigma }\left(\mathit{t}-{\mathit{t}}_{\mathit{k}}\right)-\mathrm{\sigma }\left(\mathit{t}-{\mathit{T}}_{\mathit{a}1}\right)\right)\cdot \left(\mathit{t}-{\mathit{t}}_{\mathit{k}}\right)+{\mathit{a}}_{\mathit{Max}}^{+}\cdot \mathrm{\sigma }\left(\mathbf{t}-{\mathbf{T}}_{a1}\right)\cdot \left({\mathit{T}}_{\mathit{a}1}-{\mathit{t}}_{\mathit{k}}\right)\\ +{\mathit{a}}_{\mathit{Max}}^{-}\left(\mathrm{\sigma }\left(\mathit{t}-{\mathit{T}}_{\mathit{a}2}\right)-\mathrm{\sigma }\left(\mathit{t}-{\mathit{t}}_{\mathit{E}}\right)\right)\cdot \left(\mathit{t}-{\mathit{T}}_{\mathit{a}2}\right)+{\mathit{a}}_{\mathit{Max}}^{-}\left(\mathrm{\sigma }\left(\mathit{t}-{\mathit{t}}_{\mathit{E}}\right)\right)\cdot \left(\mathit{t}-{\mathit{T}}_{\mathit{a}2}\right)\end{array}$$

$$\begin{array}{c}{\mathit{s}}_{\mathit{x}}\left(\mathit{t}\right)={\mathit{P}}_{\mathit{Z}}^{\prime }\left({\mathit{t}}_{\mathit{k}}\right)+{\mathit{v}}_{\mathit{x}0}\mathit{t}+{\mathit{a}}_{\mathit{Max}}^{+}\left(\mathrm{\sigma }\left(\mathit{t}-{\mathit{t}}_{\mathit{k}}\right)-\mathrm{\sigma }\left(\mathit{t}-{\mathit{T}}_{\mathit{a}1}\right)\right)\cdot \frac{{\left(\mathit{t}-{\mathit{t}}_{\mathit{k}}\right)}^2}{2}+{\mathit{a}}_{\mathit{Max}}^{+}\cdot \mathrm{\sigma }\left(\mathit{t}-{\mathit{T}}_{\mathit{a}1}\right)\\ \cdot \left({\mathit{T}}_{\mathit{a}1}-{\mathit{t}}_{\mathit{k}}\right)\cdot \left(\mathit{t}-{\mathit{T}}_{\mathit{a}1}\right)+{\mathit{a}}_{\mathit{Max}}^{-}\left(\mathrm{\sigma }\left(\mathit{t}-{\mathit{T}}_{\mathit{a}2}\right)-\mathrm{\sigma }\left(\mathit{t}-{\mathit{t}}_{\mathit{E}}\right)\right)\cdot \frac{{\left(\mathit{t}-{\mathit{T}}_{\mathit{a}2}\right)}^2}{2}\\ +{\mathit{a}}_{\mathit{Max}}^{-}\left(\mathrm{\sigma }\left(\mathit{t}-{\mathit{t}}_{\mathit{E}}\right)\right)\cdot \left({\mathit{T}}_{\mathit{a}2}-{\mathit{t}}_{\mathit{E}}\right)\cdot \left(\mathit{t}-{\mathit{t}}_{\mathit{E}}\right)\end{array}$$

being represented. σ ( x ) stands for the well-known sigma function from mathematics, which assumes the value one for arguments greater than or equal to zero (x ≥ 0) and is equal to zero otherwise. v _x0 stands for the initial speed at the beginning of the individual movement. Accordingly, the planning of individual movements TE, on the basis of which a position curve s _x , a speed curve v _x and an acceleration curve a _x are defined, can take place by defining the functions presented above, for example by specifying times T _a1 and T _a2 . In an advantageous manner, boundary conditions can also be specified for this, such as s _x (t _E )=E′, v _x (t _E )=v _tE . In particular, the speed v _tE can be chosen to be equal to zero, but also different from zero.

Corresponding to the above explanations, to plan a time-optimal individual movement TE, acceleration phases with maximum positive acceleration a ⁺ _max , with maximum negative acceleration a ^- _max , and with zero acceleration, i.e. acceleration a _x =0, must be specified. in the in Figure 3a The procedure shown is done by specifying points in time T _a1 and T _a2 , which limit the times of the acceleration phases mentioned. The speed curves v _x and position curves s _x associated with the acceleration curve a _x adjust themselves in accordance with the specified acceleration curves. The widths of the acceleration phases delimited by the points in time T _a1 and T _a2 with accelerations other than zero are usually specified in this case in such a way that the resulting speeds do not exceed the specified limits v ⁺ _max , v ⁻ _max . It should be noted here that lower (constant) values than the maximum accelerations possible due to the kinematic limitations of the drives can also be specified for the acceleration of the load 8 along the movement directions X, Y.

Kinematic and/or geometric limit values can, for example, be stored in the computing unit 12 or can be specified for the computing unit 12 . Further kinematic limit values are preferably a maximum speed v _Tmax and/or a maximum acceleration a _Tmax of the running element 5, or a maximum speed v _Hmax and a maximum acceleration a _Hmax of the lifting drive in the Y direction. A geometric limitation can be given, for example, by a maximum deflection angle Θ _XYmax of the load bearing element 7 in the plane E _XY . In a third direction of movement of the lifting device in the Z-direction, a maximum speed v _Smax and a maximum acceleration a _Smax of the supporting structure 3 can also be specified as kinematic limit values and a maximum deflection angle Θ _ZYmax of the load bearing element 7 in the plane E _ZY as a geometric limit value. In addition to planning time-optimal individual movements TE, however, other approaches to planning individual movements TE can also be used.

In many cases it proves to be advantageous in this connection to plan the individual movements TE _x , TE _y (and possibly TE _z ) along the axes X, Y (and possibly Z) independently of one another. This means that there is no connection between the planned individual movements TE _x , TE _y (possibly TE _z ) on the respective axes, which could be expressed mathematically, for example, and when there is a change in the position P _z of the load 8 along a first direction of movement, for example the X-axis, a change of the position Pz of the load 8 also along a second direction of movement, for example the Y-axis.

The planned individual movements TE are subsequently executed either simultaneously or at different times. A staggering of planned individual movements TE can be necessary in particular in the case of prohibited areas V _i or obstacles 11 described above. So it may be necessary for driving around an obstacle 11 to begin a lowering movement in the Y-direction with a delay. An individual movement TE _Y planned in the Y direction would therefore only be started with a time offset after the individual movement planned in the X direction had already started. The specification as to which individual movement TE is to be carried out first and which individual movement TE is to be carried out later, is expressed within the scope of the present invention by a so-called movement sequence, which is transmitted, for example, to crane controller 16 or the computing unit 12 provided in crane controller 16 via a suitable interface can be specified. A sequence of movements can thus be stored in the processing unit 12 . A sequence of movements therefore defines the order in which the planned individual movements TE are to be carried out. A movement sequence can read, for example: "First horizontal movement in the X direction, only then vertical movement in the Y direction." A movement sequence can also be in the form of a table in which the planned individual movements TE are assigned start times at which they are started. A movement sequence can also include time intervals which define waiting times which must at least be provided between the start times of successive individual movements TE.

A central problem in the manipulation of loads 8 by lifting devices 1, which can either be solved in many cases by suitable trajectory planning, but can usually be at least greatly reduced, is the problem of load oscillations. Above all, rapid movement processes of lifting devices can often stimulate undesired vibrations and/or pendulum movements of transported loads 8 or of load-receiving elements. Vibrations of loads 8 can in turn delay handling and manipulation processes, since loads such as containers often cannot be placed at all or at least not with sufficient precision in such cases and it is first necessary to wait until a given vibration has subsided again. In Fig.1 the possibility of the formation of oscillations and/or pendulum movements is represented by a double arrow in the XY plane E _XY .

In the present context, it has been shown that so-called flat trajectories, i.e. trajectories that can be continuously differentiated sufficiently often depending on the specific structure of the lifting device, are an effective means of counteracting (load) vibrations and/or represent pendulum movements. This approach is based on the fact that a situation like that in 1 lifting devices 1 shown is a "flat system" in the control engineering sense. As is known, flat systems are systems which have a so-called flat output.

In the case of a flat system, such as the lifting device 1 in question, flat outputs and their derivations allow the representation (also “parameterization”) of the internal state or system variables of the flat system. The internal state or system variables of a flat system can therefore be represented as functions of the flat outputs and their derivatives, which is of course known to those skilled in the field of control engineering. For the suppression of vibrations of a load 8 transported by a lifting device 1, the fact that (in an ideal view) a control designed using a flat output cannot excite any vibrations or pendulum movements of the load is important at this point.

In the case of the lifting device 1 considered here, the position curves of the load 8 along the directions of movement X, Y represent flat exits of the "lifting device" 1 system. This shows that it is sufficient to suppress vibrations and/or pendulum movements caused by the planned Individual movements TE specified position profiles s _x (t), s _y (t) as quadruple continuous temporally differentiable position profiles s _x (t), s _y (t). In this way, oscillations and/or pendulum movements can be suppressed without having to rely on measurements of the load position Pz. At this point it should be mentioned that the use of trajectories that can be differentiated more often and continuously can ensure even smoother motion courses that are even gentler on the drives.

In order to ensure that the position curves s _x (t), s _y (t) defined by the specified individual movements TE can actually be continuously differentiated fourfold, the position curves s _x (t), _sy (t) can be filtered before they are executed. However, the quadruple differentiability described can also be achieved in a different way than by filtering, for example by polynomial approaches for the predetermined position, speed and/or acceleration curves. The filtering of individual movements TE, which are present as scalar curves, is significantly simpler than the filtering of multi-dimensional curves. This is another reason why the use of individual movements TE represents a significant advantage when controlling lifting devices 1.

$$v_T={\dot{x}}_L-\frac{{\dot{y}}_L{\ddot{x}}_L-\left(y_T-y_L\right){\stackrel{⃛}{x}}_L}{{\ddot{y}}_L+g}-\frac{\left(y_T-y_L\right){\ddot{x}}_L{\stackrel{⃛}{y}}_L}{{\left({\ddot{y}}_L+g\right)}^2}$$

$$\begin{array}{c}{a}_T={\ddot{x}}_L-\frac{{\ddot{y}}_L{\ddot{x}}_L+2{\dot{y}}_L{\stackrel{⃛}{x}}_L-\left(y_T-y_L\right)x_L^{\left(4\right)}}{{\ddot{y}}_L+g}+\frac{2{\dot{y}}_L{\ddot{x}}_L{\stackrel{⃛}{y}}_L-2\left(y_T-y_L\right){\stackrel{⃛}{x}}_L{\stackrel{⃛}{y}}_L-\left(y_T-y_L\right){\ddot{x}}_L{y}_L^{\left(4\right)}}{{\left({\ddot{y}}_L+g\right)}^2}\\ +\frac{2\left(y_T-y_L\right){\ddot{x}}_L{\stackrel{⃛}{y}}_L^2}{{\left({\ddot{y}}_L+g\right)}^3}\end{array}$$

The approach described for generating flat trajectories by means of a suitable filtering or a polynomial approach can also be used in a particularly advantageous manner to the above-mentioned kinematic limitations for the drives of the lifting device as well as the geometric limitation of the deflection angle of the load. For example, the partial movements of the load 8 are related to the movement of the running element 5 via the known pendulum equations: $$x_T=x_L+\frac{{\ddot{x}}_L\left(y_T-y_L\right)}{{\ddot{y}}_L+G}$$

$$v_T={\dot{x}}_L-\frac{{\dot{y}}_L{\ddot{x}}_L-\left(y_T-y_L\right){\stackrel{⃛}{x}}_L}{{\ddot{y}}_L+G}-\frac{\left(y_T-y_L\right){\ddot{x}}_L{\stackrel{⃛}{y}}_L}{{\left({\ddot{y}}_L+\mathrm{<figure-callout\; id="2a"\; label="G"\; filenames="imgf0006.png"\; state="\{\{state\}\}">G</figure-callout>}\right)}^2}$$

$$\begin{array}{c}{a}_T={\ddot{x}}_L-\frac{{\ddot{y}}_L{\ddot{x}}_L+2{\dot{y}}_L{\stackrel{⃛}{x}}_L-\left(y_T-y_L\right)x_L^{\left(4\right)}}{{\ddot{y}}_L+G}+\frac{2{\dot{y}}_L{\ddot{x}}_L{\stackrel{⃛}{y}}_L-2\left(y_T-y_L\right){\stackrel{⃛}{x}}_L{\stackrel{⃛}{y}}_L-\left(y_T-y_L\right){\ddot{x}}_L{y}_L^{\left(4\right)}}{{\left({\ddot{y}}_L+G\right)}^2}\\ +\frac{2\left(y_T-y_L\right){\ddot{x}}_L{\stackrel{⃛}{y}}_L^2}{{\left({\ddot{y}}_L+G\right)}^3}\end{array}$$

usw. notiert sind. Entsprechend den obigen Ausführungen stellen die angegebenen Gleichungen eine flache Parametrierung der Zustandsgrößen x_T, v_T, a_T als Funktion der flachen Ausgänge ẍ_L, y_L dar. Der angegebene Zusammenhang verdeutlicht, dass sich Vorgaben hinsichtlich der Verläufe der Koordination x_L und y_L in unmittelbarer Weise auf die Bewegung des Laufelements 5 auswirken.The variables x _T , v _T , a _T stand for the movements of the running element 5, x _L and y _L on the other hand for the coordinates of the load 8, whose corresponding derivatives are denoted by ẋ _L , ẍ _L , ${\stackrel{⃛}{x}}_L,{\mathrm{<figure-callout\; id="4"\; label="x\; L"\; filenames="imgf0001.png"\; state="\{\{state\}\}">x</figure-callout>}}_L^{}$

etc. are noted. According to the explanations above, the given equations represent a flat parameterization of the state variables x _T , v _T , a _T as a function of the flat outputs ẍ _L , y _L . The given relationship makes it clear that specifications regarding the courses of the coordination x _L and y _L affect the movement of the running element 5 in a direct manner.

In order to implement the filtering described for generating flat trajectories, a suitable filter F can be used, for example, such as a moving average filter (MA filter, "moving average filter"). A schematic representation of such filtering is in Figure 3b shown. Figure 3b shows a general filter F, which records position curves s, speed curves v and acceleration curves a, and outputs filtered position curves s̃, speed curves ṽ and acceleration curves ã. The filter F can be designed to also output time derivatives of the variables mentioned, in particular of incoming acceleration curves. The filter F can be designed as a single-variable system, and can record only one of the named variables, position s, speed v and acceleration a, and output it again in filtered form. However, the filter F can also be designed as a multivariable system and process several variables at the same time. The filter F can be implemented in the control unit 12 in a known manner.

The filter time τ _filt of a filter F implemented as an MA filter can be selected here in a particularly advantageous manner as a function of the geometry of the lifting device and the pendulum equations. By choosing larger time constants, the previously planned individual movements can be filtered even more and, for example, even more conservative curves can be specified for the running element. Through a repeated Filtering, individual movements TE can be generated in an extremely advantageous manner, by which kinematic limitations specified for the drives of the lifting device 1, such as speed, acceleration, jerk limitations, are taken into account.

How the definition of prohibition zones V _i can be done concretely is further explained in 4 shown closer. For example, an envelope of an obstacle 11 in the form of a rectangle can be used, which completely encloses the obstacle 11 . The height H _R1 of the rectangle corresponds at least to the maximum extent of the obstacle 11 in the Y direction and the width W _R1 of the rectangle corresponds at least to the maximum extent of the obstacle 11 in the X direction. This is only to be understood as an example; of course, other geometric definitions of the prohibited zone V ₁ are also conceivable. In general, for example, a single forbidden zone V ₁ can enclose several obstacles 11 . However, a finer definition of several prohibited zones V _i can also be applied, e.g. based on the concrete outlines of obstacles 11.

Crucial importance comes at a like in the figures 1 and 4 shown situation of the order in which the planned individual movements TE are executed. How based on 4 can be recognized immediately, starting from the command time t _k , a lowering movement in the Y direction by the individual movement TE _Y may only be carried out if a collision with the obstacle 11 can be ruled out. According to the invention, a so-called movement sequence is specified to determine the order in which the planned individual movements TE are executed, which determines the order in which the specified individual movements TE are to be executed and the times at which these individual movements TE are started.

A first possibility is to perform the planned individual movements TE at different times, ie to wait after the implementation of an individual movement TE and only to continue with the next individual movement TE according to the movement sequence after a predetermined waiting time.

Specifically, a sequence of movements can specify, for example, that in the in 4 In the situation shown, a lifting movement is first carried out in the Y direction as a single movement TE _Y2 ("Hoist Up"), then the vertical single movement TE _x is carried out in the X direction ("Move Trolley"), and only then the single movement TE _Y1 in the Y-direction as a lowering movement ("Hoist Down"). The waiting time between these individual movements TEx, TE _Y , TE _Y2 can be predefined or determined depending on the situation. For example, it is possible to wait until the individual movement TE _Y2 has ended and only after it has ended with the next individual movement TEx, either along the same movement direction X, Y or along a different one Direction of movement X, Y can be started. However, time is lost in this way due to the waiting times to be provided between the various individual movements TEx, TE _Y , TE _Y2 . For this reason, the planned individual movements TE can also be carried out with a time overlap in an advantageous manner. In this case, temporally overlapping means that, for example, an individual movement in the Y-direction has already started before an individual movement in the X-direction has been completely completed. Such an overlapping of individual movements TE can also be recorded in a sequence of movements within the scope of the present invention.

In the course of determining the sequence of movements in which the planned individual movements are to be carried out, it is often of particular advantage if it is also checked whether the resultant replanning trajectory TU may result in a collision of the load 8 with a prohibited zone V _i .

How to proceed in this regard is in Figures 5a-5c shown. Figures 5a and 5b show on the one hand acceleration, speed and position profiles ( _ax , _vx , _sx and _ayvy , _sy ) for the directions of movement X and _Y , as they can be used for replanning the movement of a load 8 according to the invention. In the situation shown, the load 8 is to the left of a newly specified obstacle 11n at the command time t _K , as in FIG Fig.5c is evident. Accordingly, the individual movements TE _Y1 , TE _Y2 planned in the Y direction can be accepted without restriction. A collision cannot be brought about purely by a movement in the Y direction starting from the position P _z (t _k ).

In the X-direction, however, it is evident that the individual movement TE _xa would lead to a collision with the obstacle 11. The individual movement TE _xa planned at the beginning is in Fig.5a represented by the dash-dot curves s _xa , v _xa and a _xa . In combination with the lifting movement TE _Y2 planned for the Y direction, the in Figure 5c first replanning trajectory TU ₁ shown in broken lines, which would, however, result in a collision with the new prohibited zone V _1n . For this reason, the individual movement TEx initially planned for the X-direction is not carried out and instead a braking process is carried out for a specified duration T _St . The braking process corresponds to that in Figure 5a initially planned phase with negative acceleration. Based on this, a new individual movement TE _xn is planned in the X direction and this is carried out instead of the previously planned, old individual movement TE _xa after the end of the braking process.

In a particularly elegant way, a check as to whether a collision with an obstacle is to be expected can be carried out in the following way: Before at least one planned individual movement TE is carried out, so-called collision times t _iX , t _iY are determined and compared with one another. among the Collision times t _iX , t _iY are to be understood as the respective times at which the load 8 derived a projection _Si ′ or S _i “of a prohibition zone V _i placed around an obstacle 11 by means of the respective planned individual movements TEx, TE Y , Support point S _i (English "Keypoints") on the respective direction of movement X, Y would reach.

As mentioned, support points S _i are preferably corner points of forbidden zones V _i . In order to check whether an expected replanning trajectory TU would lead to a collision of the load 8 with an obstacle 11 specified in the working area 15, in Figure 5c In the situation illustrated, it can be checked whether the corresponding collision time t _1X for the individual movement TE _xa along the X axis is before the corresponding collision time t _1Y for the individual movement TE _Y2 along the Y axis, i.e. t _iX <t _iY applies (specifically to Figure 5c the inequality would be t _iX <t _iY ). In this case, in the in Figure 5c situation shown can be concluded to a collision. The corresponding collision times t _ix , t _iy are here in the Figures 5a and 5b shown.

In the procedure described, particular attention must be paid to the Y coordinate of the load position Pz, i.e. the projection Pz" of the load position Pz onto the Y axis. It must be taken into account whether the Y coordinate Pz" of the load position Pz at the beginning of a single movement TE _Y in the Y direction is larger or smaller than the projection S _i " of the next supporting point S _i in the Y direction on the Y axis. In many practically relevant cases, the load position Pz is at the beginning of a newly planned individual movement TE through the load position Pz at the command time t _k , i.e. P _Z (t _k ). If the projection S _i " of the next supporting point S _i in the Y direction on the Y axis is smaller than the projection Pz" of the load position P _Z on the Y axis axis, the condition for a collision is met exactly when t _iY <t _iX applies.

Individual movements TE _x , TE _Y are often not available in analytical form. In such cases, it is also advantageous to use numerical methods for searching for zeros in order to determine the collision times t _iX , t _iY , such as the well-known bisection method or the Newton method.

In practical implementation, it is often advantageous to combine both analytical and numerical methods in order to determine the collision times t _iX , t _iY that are sought. Such a case will be described below. The acceleration curves a _x and a _y are initially specified as constant piece by piece as described. The associated position curves s _x and s _y can easily be calculated analytically for these piecewise constant acceleration curves a _x and a _y . For the resulting analytical descriptions of the position curves s _x (t) and s _y (t), the collision times t _iX , ti _Y can be calculated with little effort, for example by using the zeros t _x0 , t _y0 of the functions f _x (t) = s _x (t)-Si', f _y (t) = s _y (t)-Si' can be determined. For this Zeros t _x0 , t _y0 by definition f _x (t _x0 ) = f _y (t _y0 ) =0. Of course, the height and width of the load 8 can also be taken into account in the formulas f _x (t) and f _y (t), which is usually defined by the height H ₇ of the load bearing element 7 plus the height Hg of a container 9 in the Y direction, as well as half the width B ₇ of the load receiving element 7 (usually corresponds to half the width Bg of the container 9) are given. Depending on whether the load 8 approaches the next support point S _i from the left, right, above or below, the function f _x (t) can be increased or decreased by half the width Bg, for example.

und ${\tilde{f}}_{\mathit{y}}\left(\mathit{t}\right)={\tilde{s}}_{\mathit{y}}\left(\mathit{t}\right)-{\mathit{S}}_{\mathit{i}}^{"}$

gesucht werden. Diese Nullstellen entsprechen dann den gesuchten Kollisionszeitpunkten t_iX, t_iY für die gefilterten Positionsverläufe s̃_x (t) und s̃_y (t).If the individual movements TEx, TE _Y are filtered, for example by means of an MA filter described above, the position profiles s _x (t) and _sy (t) are filtered to form filtered position profiles s̃ _x ( t ) and _sy (t). For such filtered position curves s̃ _x ( t ) and s _y (t), the property of an MA filter can now be exploited that the zeros t _x0 , t _y0 determined from the function f _x (t) shown above are filtered by a maximum of the filter time τ _filt of the MA filter used for filtering can be shifted. In the case of double filtering, a time interval of length 2 · τ _filt can be placed around the previously determined zeros t _x0 , t _y0 , with the zeros t _x0 , t _y0 at the beginning of the interval at the left interval boundary. In such a time interval, a bisection method can now be used to find the zeros of the functions f _x (t) = ${\tilde{s}}_{\mathit{x}}\left(\mathit{t}\right)-{\mathit{S}}_{\mathit{i}}^{\prime }$

and ${\tilde{f}}_{\mathit{y}}\left(\mathit{t}\right)={\tilde{s}}_{\mathit{y}}\left(\mathit{t}\right)-{\mathit{S}}_{\mathit{i}}^{"}$

be searched. These zeros then correspond to the collision times t _iX , t _iY sought for the filtered position curves s̃ _x ( t ) and s̃ _y ( t ).

In addition to the described comparison of two collision times t _iX , t _iY , another approach to collision checking can be mentioned. First of all, only the collision time t _iy can be calculated, which indicates when along the Y axis a planned individual movement TE _Y in the Y direction will result in a projection of a specified support point S _i "on the Y axis. Based on this collision time t _iy, the position s _X (t _iy ) can also be determined, which describes the position on the X axis specified at the time of collision t _iy by the planned individual movement TE _x in the X direction.

The check as to whether a collision with an obstacle 11 is to be expected as a result of planned individual movements TE can then be carried out by comparing the position s _x (t _iy ) with the projection Si' of the support point Si on the X axis. in Figures 5a-5c In the concrete case shown, a collision can be concluded, for example, if one of the conditions s _x (t _1y )>S ₁ 'or s _x (t _2y )<S ₂ ' is met. In this way, computing time can be saved compared to the procedure described above, since only a collision time t _iy has to be determined. This approach is in Figure 5a indicated by the points s _xa (t _1y ) and s _xn (t _1y ). While s _xa (t _1y ) lies above the projection S ₁ ' (resulting in a would lead to a collision), s _xn (t _1y ) lies below the projection S ₁ ', with the desired effect of collision avoidance.

On the other hand, to check a collision, it is also possible to first determine the collision time t _ix , using this collision time t _ix , to determine the corresponding position on the Y axis s _y (t _ix ), and the corresponding position on the Y axis Axis s _y (t _x ) with a projection Si" of a support point Si on the Y-axis. Im in Figures 5a-5c In the case shown, a condition to be met for a collision would be s _y (t _1x )<S ₁ "(not shown).

If one of the above-mentioned preliminary calculations before the execution of at least one individual movement TE shows that a collision is to be expected, the individual movement TE that caused the collision is not carried out and instead is carried out along the direction of movement X, Y for which the at least one individual movement that has not been carried out is planned , in Figure 5c the individual movement TEx in the direction of movement X, a specified braking process is carried out. The braking process is carried out at least for the duration of a predefined minimum braking time T _St . A braking process specifies accelerations for the movement of the load 8 in such a way that the speed of the load 8 is reduced along the direction along which braking is required. In the case of positive speeds, negative accelerations are specified and vice versa. In an advantageous manner, the maximum permissible accelerations can also be used during a braking process.

After the minimum braking time T _St , at least one individual movement TE that has not been carried out is rescheduled to form a new individual movement TE in an advantageous manner in a replanning step. In a further checking step with the at least one new individual movement TE, it can be checked again whether the replanning trajectory TU to be expected on the basis of the new individual movement TE leads to a collision. If no collision is detected, the newly planned individual movement TE can be carried out.

However, if a collision of the load 8 with an obstacle 11 is again predicted in the previous checking step, a predetermined braking process can advantageously be carried out again for at least one further minimum braking time T _St . Thereafter, a replanning step and a verification step following this replanning step can be performed again.

By repeating the braking process described above, the load 8 can also be brought to a complete standstill. The further planning of individual movements TE then takes place based on the standstill of the load 8 . The possibility, by means of the method according to the invention, starting from the standstill of the load 8, corresponding individual movements TE and thus one of these individual movements TE Planning the resulting trajectory T immediately opens up the option of also planning fundamentally new trajectories T for the movement of a load 8 using the method according to the invention. If the load 8 is at a standstill at the beginning of a movement process and no trajectory T is known for its movement from the starting point A to the end point E, the standstill at the starting point A can be assumed/specified as the end of a braking process that has been carried out several times and by using the method according to the invention A first trajectory T for transferring the load 8 from a standstill at the starting point A to the end point E can also be planned using the method.

Similar to the previously described determination of the collision times t _iX , t _iy , a time interval can also be specified for a braking process, in which the load 8 can be completely brought to a standstill. Specifically, the limits t _k (command time) and t _k +T _TE can be specified for this time interval, with T _TE describing the duration of a planned individual movement TE. Within this time interval, if a braking process is carried out repeatedly, the load 8 comes to a standstill, with the specific point in time being able to be determined, as before, for example by a bisection method.

Even though the present invention has so far been described using a trajectory T in the XY plane E _XY , an extension to a three-dimensional trajectory T in space is also possible. The basic method for replanning three-dimensional trajectories T on the basis of preferably independent individual movements remains unchanged. If the load 8 is also moved by the lifting device 1 along a third direction of movement Z, in order to replan the trajectory T according to the method according to the invention, at least one individual movement TE _{Z is also planned for the third direction of movement Z} , which is carried out according to a predefined movement sequence in addition to those for the first Direction of movement X and for the second direction of movement Y planned individual movements TEx, TE _Y is executed.

To use the present invention when planning three-dimensional trajectories, it is often advantageous to specify a 3D workspace to limit the movement of the load 8 instead of a two-dimensional workspace 15 . In contrast to a purely two-dimensional view, however, it may also be necessary in the 3D case to take into account the extension of an obstacle 11 and the extension of a load 8 in the Z-direction. This can be necessary, for example, in assembly halls, where obstacles 11 arranged on the walls protrude into the space of the assembly hall. In such cases, situations can arise in which an obstacle 11 can also be avoided by suitable lowering movements, which can also be implemented using the method according to the invention.

Such a case is in 6 shown, where, as in the previous examples, at the command time tk starting from the position P _z (t _k ), new individual movements TE _X1 , TE _X2 , TE _Y1 , TE _Y2 , TE _Y3 are planned. The important case is shown that several individual movements TE _X1 , TE _X2 are also planned in the X direction, which is also possible within the scope of the present invention. In 6 the obstacle 11a is avoided, for example, by a lifting movement TE _Y3 and the obstacle 11b on the other hand by a lowering movement TE _Y2 . The final transfer to the end point E takes place by means of a final lifting movement TE _Y1 .

In many practical applications, it can be advantageous in this context to use optical measuring systems for detecting the load position P _Z or obstacles 11, as is the case, for example, in FIG EP 3 653 562 A1 is described. Appropriate camera systems in particular, but also laser scanners, are to be mentioned here as optical measuring systems. A camera can be mounted/installed directly on the trolley of a lifting device 1 for the purpose of monitoring obstacles 11 whose position can be changed in the working area 15 . In concrete terms, an optical detection of obstacles can supply information about how high and at which spatial positions obstacles 11 to be avoided are arranged. If a change in the position of an obstacle 11 is detected, a new forbidden zone V can be derived therefrom and, as described, a trajectory for the movement of a load can be replanned. In addition to camera and/or laser scanning systems, other approaches to detecting obstacles are also conceivable. In many cases, automation or logistics systems implemented in software also provide information about obstacles to be taken into account 11.

Claims (15)

Method for controlling a lifting device (1) which moves a load (8) along a first direction of movement (X) and along a second direction of movement (Y) within a predetermined working area (15) of the lifting device (1) according to a predetermined trajectory (T) of moves from a starting point (A) to an end point (E), characterized in that at a command time (t _k ) during the movement of the load (8) an obstacle (11n) that is new to the movement of the load (8) and which lies between the position ( _Pz ) assumed by the load (8) and the end point (E) at the command time (t k ) and the end point (E) is specified and/or an existing obstacle (11) between the load at the command time (t _k ). (8) assumed position (Pz) and the end point (E) is arranged to a new obstacle (11n) for the movement of the load (8) is changed that taking into account given kinematic limitations of the lifting device (1) for the first Direction of movement (X) and for the second direction of movement (Y) at least one individual movement (TEx, TE _Y ) is planned, which further movement of the load (8) along the respective direction of movement (X, Y) from the command time (t _k ) where at least one individual movement (TEx, TE _Y ) ends in a projection (E', E") of the end point (E) onto the respective direction of movement (X, Y) for each direction of movement (X, Y), and that the planned individual movements (TEx, TE _Y ) are executed according to a predetermined sequence of movements in order to move the load (8) without colliding with the new obstacle (11n) along the first direction of movement (X) and along the second direction of movement (Y) according to a sequence of movements of the planned individual movements (TEx, TE _Y ) resulting replanning trajectory (TU) to move on. Method according to Claim 1, characterized in that the individual movements (TEx, TE Y ) planned for the first direction of movement (X) and for the second direction of movement ( _Y ) are planned as individual movements (TEx, TE _Y ) that are independent of one another. Method according to one of Claims 1 to 2, characterized in that the planned individual movements (TEx, TE _Y ) each comprise a position profile (s _x (t), s _y (t)) that can be continuously differentiated at least four times over time, the position profiles (s _x (t), s _y (t)) are filtered by means of a filter (F) with a specifiable time constant in order to produce the at least quadruple continuous time differentiability, with the time constant of the filter (F) being selected as a function of the geometry of the lifting device (1). in order to comply with the specified kinematic limitations of the lifting device (1) in a combined execution of the individual movements (TEx, TE _Y ). The method according to any one of claims 1 to 3, characterized in that for the second direction of movement (Y) another individual movement (TE _Y2 ) is planned, which Load (8) in combination with the individual movement (TEx) planned along the first movement direction (X) around the newly specified and/or changed obstacle (11n), and that the second individual movement (TE _Y2 ) according to the specified sequence of movements before the for the second direction of movement (Y) already planned individual movement (TE _Y ) is executed. Method according to one of the preceding claims, characterized in that the sequence of movements is specified such that individual movements (TEx) along the first direction of movement (X) and individual movements (TE _Y ) along the second direction of movement (Y) are started alternately. Method according to one of the preceding claims, characterized in that the sequence of movements is specified such that a single movement (TEx) along the first direction of movement (X) and a single movement (TE _Y ) along the second direction of movement (Y) are carried out with a time overlap. Method according to one of the preceding claims, characterized in that before the execution of at least one planned individual movement (TEx, TE _Y ) it is checked whether the replanning trajectory (TU) to be expected leads to a collision of the load (8) with a load (8) in the working area (15) predetermined obstacle (11a, 11n) leads. Method according to Claim 7, characterized in that to check whether the replanning trajectory (TU) to be expected leads to a collision of the load (8) with an obstacle (11a, 11n) specified in the working area (15), projections (Si', S _i ") of a support point (S _i ) derived from the specified obstacle (11a, 11n) in the directions of movement (X, Y) are determined, that a collision time (t _ix ) is determined at which the load (8) with the for the first direction of movement (X) planned individual movements (TE _x ) the projection (S _i ') on the first direction of movement (X) is reached and a collision time (t _iy ) is determined at which the load (8) with that for the second direction of movement ( Y) planned individual movement (TE _y ) reaches the projection (Si") onto the second direction of movement (Y), and that the determined collision times (t _ix , t _iy ) are compared with one another. Method according to Claim 7, characterized in that a projection (S _i ' , S _i ") of a support point (Si) derived from the specified obstacle (11a, 11n) in one of the directions of movement (X, Y) is determined, that a collision time (t _ix , t _iy ) is determined at which the load (8th ) with the individual movement (TE _x , TE _y ) planned for this movement direction (X, Y) the determined projection (Si', S _i ") reaches that a position (s _x (t _ix ), s _y (t _iy ) ) of the load (8) is determined on the other direction of movement (X,Y), which is assumed by the load (8) at the determined collision time (t _iy , t _iy ), and that the determined position (s _x (t _ix ) , s _y (t _iy )) with a projection (Si', S _i ") of the supporting point (S _i ) onto that direction of movement (X, Y) for which the position (s _x (t _ix ), s _y (t _iy )) of the load (8) was determined is compared. Method according to Claim 8 or 9, characterized in that the times of collision (t _ix , t _iy ) are determined using a zero-point search method. Method according to one of Claims 8 to 10, characterized in that in the event of a collision with an obstacle (11a, 11n) being determined, the at least one individual movement (TEx, TE _Y ) is not carried out and that instead along that direction of movement (X, Y) , for which the at least one individual movement (TE _X , TE _Y ) that has not been carried out has been planned, a predetermined braking process is carried out for at least the duration of a predetermined minimum braking time (Tst). Method according to Claim 11, characterized in that instead of the at least one individual movement (TE _X , TE _Y ) not carried out for the corresponding direction of movement (X,Y), a new individual movement (TE _X,n , TE _Y,n ) is planned that it is checked whether the replanning trajectory (TU) resulting from the newly planned individual movements (TE _X,n , TE _Y,n ) leads to a collision of the load (8) with an obstacle (11a, 11n) specified in the working area (15). , and that the new individual movement (TE _X,n , TE _Y,n ) is carried out if no collision is detected, or that the specified braking process is continued for at least another minimum braking time (Tst) and a new individual movement is planned (TE _{X ,n} , TE _Y,n ) and a check of the replanning trajectory (TU), which results from the newly planned individual movement (TE _X,n , TE _Y,n ), can be carried out if another collision with an obstacle (11a, 11n) is detected. Method according to one of the preceding claims, characterized in that the position (Pz) of the load (8) is measured and used to plan and/or carry out the individual movements (TE _X , TE _Y ). Method according to one of the preceding claims, characterized in that the load (8) is additionally moved by the lifting device (1) along a third direction of movement (Z), the load (8) being moved within a predetermined 3D working space according to a three-dimensional trajectory ( T) is moved, and that for the replanning of the trajectory (T) also for the third direction of movement (Z) at least one individual movement (TEz) is planned and according to a predetermined movement sequence in addition to those for the first direction of movement (X) and for the second direction of movement (Y) planned individual movements (TE _X , TE _Y ) are executed. Lifting device (1) for moving a load (8) from a starting point (A) to an end point (E) according to a predetermined trajectory (T) within a predetermined working area (15) of the lifting device (1), wherein in the lifting device (1) a load-carrying element (7) for receiving the load (8) is provided with at least one Holding element (6) is connected to a running element (5), the running element (5) being movable along a first direction of movement (X) by means of a running element drive and the load-carrying element (7) being movable along a second direction of movement (Y) by means of a lifting drive, characterized in that a computing unit (12) is provided in the lifting device (1), which is designed to detect a new obstacle (for the movement of the load (8) at a command time (t _k ) during the movement of the load (8). 11n), which is arranged between the position ( _Pz ) assumed by the load (8) at the command time (t k ) and the end point (E), and/or an existing obstacle (11) which is between the position at the command time (t _k ) of the load (8) assumed position (Pz) and the end point (E) and is changed to a new obstacle (11n) for the movement of the load (8) to read that the computing unit (12) is further configured , taking into account given kinematic limitations of the lifting device (1) for the first direction of movement (X) and for the second direction of movement (Y) to plan an individual movement (TE _X , TE _Y ), which the further movement of the load (8) along of the respective direction of movement (X, Y) from the command time (t _k ), with the individual movements (TE _X , TE _Y ) each being in a projection (E', E") of the end point (E) onto the respective direction of movement (X, Y) and that the computing unit (12) is designed to control the running element drive and the lifting drive of the lifting device (1) in order to carry out the planned individual movements (TE) according to a predetermined movement sequence and thus the load (8) without colliding with a Obstacle (11, 11n) along the first direction of movement (X) and along the second direction of movement (Y) according to a replanning trajectory (TU) resulting from the movement sequence of the planned individual movements (TE).

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