DE102018203667A1 - Method for automated motion planning in a planar drive - Google Patents

Abstract

The invention relates to a method for operating a planar drive (10), preferably in the context of an industrial production plant, wherein the planar drive (10) comprises a stator and at least one mover (20, 21, 22), each mover (20, 21, 22 ) is at least in relation to two linear degrees of freedom (12; 13) movable to the stator (11), wherein it is driven by the stator (11), at least one position detecting means (14) is provided, with which the position of each mover (20; 21, 22) relative to the stator (11) can be determined.
According to the invention, at least one condition is predetermined, which is to be maintained during a movement of the at least one mover (20; 21; 22) relative to the stator (11), wherein the at least one mover comprises a first mover (21), wherein an initial and at least an end point (30; 31) of a movement of the first mover (21) is predefined, wherein a movement sequence of the first mover (21) between the start point and the at least one end point (30; 31) is automatically selected such that the at least one Condition is met, wherein an end point (31) is reached, wherein the first mover (21) is moved using the stator (11) and the position detecting device according to the selected movement sequence.

Description

The invention relates to a method for operating a planar drive according to the preamble of claim 1.

From the US 9 685 849 B2 is known a corresponding planar drive. Next is from the DE 10 2014 212 256 A1 the use of such a planar drive in a production plant known.

An advantage of the present invention is that many different products can be produced very flexibly with the corresponding production plant, whereby nevertheless only a very small expenditure is incurred for the user of the production plant for planning the movement of the movers of the planar drive. In addition, the production plant works particularly effectively, in particular, the unproductive movement times of the mover are minimized.

According to the independent claim, it is proposed to specify at least one condition to be observed during a movement of the at least one mover relative to the stator, wherein the at least one mover comprises a first mover, wherein an initial and at least one end point of a movement of the first Movers are given, wherein a movement of the first movers between the start and the at least one endpoint is automatically selected so that the at least one condition is met, with an end point is reached, the first mover using the stator and the position detection device accordingly the selected movement is moved.

It is understood that said at least one condition does not directly relate to the content, that the movers follow said course of motion. The at least one mover is preferably provided with permanent magnets, most preferably on the side facing the stator. The stator may be provided with electric coils to move the mover in the sense of a linear motor. The stator may be provided with movable, in particular rotatable, driven permanent magnets to move the mover. The at least one condition is preferably a physical condition. The said movement sequence may also include standstill phases, for example when a mover stops to allow another mover to pass for collision avoidance.

The conditions preferably include abstract conditions that are valid regardless of the specific application. They are particularly valid for many different movements of the planar drive. For example, a mover loaded with a particular sensitive product should not be allowed to stop within a certain radius of a particular processing station emitting harmful emissions. Most preferably, the abstract conditions are already determined or determined during the planning of a specific planar drive or a production plant, wherein they are stored in the relevant control software. The abstract conditions may refer to portions of the stator. For example, it may be intended to specify upper limits for the speed and / or the acceleration of the mover for partial areas of the stator. Furthermore, a group of objects can be defined in the form of an abstract condition. In particular, it is intended to objects with which the movers may be loaded. For example, a production facility may be configured to produce multiple construction variants of a product. These can be grouped in an abstract condition. Another abstract condition may in turn refer to this group, for example, by specifying a maximum acceleration for that group of objects.

The conditions further include concrete features that are dependent on the actual movement. For example, "a particular mover is loaded with a particular product or object." The concrete features are preferably unchanged during a single, associated motion sequence and are determined before the movement in question. This can also be automated, for example, when a certain empty mover was moved in the context of a leading movement process to a loading station in which he was, preferably automatically, loaded with a specific product or object. Thereupon, the concrete features can be automatically specified for the next movement sequence, that said mover is loaded with said product or object. Over several movements the concrete characteristics can change.

In order to determine the concrete condition or characteristics for carrying out the individual movement process, it is possible to use abstract conditions which, by considering the current state of the planar drive, the moving objects and systems connected by communication technology, allow closing to concrete conditions. An example of a communication-related system is a processing station which signals via a digital I / O interface whether it is in operation or not.

The abstract conditions may have a premise that targets an expression or set of occurrences of a feature possessed by an object that can be brought into a defined relation to the owner of the abstract condition by the execution of a motion. For example, a product may be sharp-edged, with the risk of injury. Therefore, concrete conditions have to be set for every movement in exactly the partial areas of the planar drive with possible manual intervention. The product type (which characterizes each object of a set of moving objects in operation) is given an abstract condition with the premise "for each object to which there is a partial-in-relation" and that a characteristic "manual intervention" with the expression "Possible" exists. Thus, the associated abstract condition would apply only to the relevant cases. Possible relations are at least: is-partial-in, is-completely-in, is-over, is-under (for vertical driving!).

The abstract conditions may have a conclusion containing the concrete conditions to be applied to a sequence of movements to be performed. To give an example: "... must apply: the movement speed is <0.2 m / s".

In the dependent claims advantageous refinements and improvements of the invention are given.

It can be provided that the movement sequence comprises a geometric trajectory along which the movement of the relevant Movers runs, wherein the movement sequence further comprises the time sequence of the movement along the trajectory. The trajectory is preferably described by a geometric curve, which most preferably relates to a predetermined reference point on the mover and / or on the stator.

It can be provided that the movement path and the time sequence are selected automatically one after the other. Preferably, the time sequence is selected after the trajectory. This reduces the effort in the automated selection of the movement. In particular, collisions of movers can often be avoided merely by selecting the time sequence in a suitable manner, with one of the affected movers typically being briefly stopped.

It can be provided that the at least one mover comprises a second mover different from the first, wherein a first condition for the first mover comprises the selected motion sequence for the second mover, wherein the first condition further comprises that the first and the second mover at a movement according to the selected movement sequence does not collide. This avoids collisions between the movers. Furthermore, a flexible adaptation to the desired transport task is possible.

It can be provided that the motion sequence of the second mover is selected again if the first condition of the first mover can not be maintained with the previously selected motion sequence of the second mover. This ensures that it is always possible to automatically find a motion sequence that meets all conditions, if it exists.

It can be provided that at least three movers are present, wherein a condition corresponding to the first condition is specified for all possible pair combinations of movers. Thus, the inventive method for any number of mover executable.

It can be provided that a second condition of a mover comprises permissible positions and / or the maximum permissible movement speed and / or the maximum permissible movement acceleration and / or the maximum movement pressure of this mover.

It can be provided that a mover is not moved if its mass exceeds a predetermined maximum mass. As a result, it is particularly avoided that the normally free-floating mover grinds on the stator and damage it.

It may be provided that the actual mass of a mover is determined using the bearing detection device. The bearing detection device is for this purpose preferably able to determine the distance of the mover to the stator perpendicular to the stator surface. For example, the stator can be provided with a plurality of grid-like distributed magnetic field sensors with which the permanent magnetic field of the Movers can be measured. It is also conceivable that the stator is provided with distributed coils which receive electromagnetic pulses emitted by the movers.

It can be provided that at least one condition comprises the optimization of a physical parameter of the planar drive or of the production facility. This is an example of an abstract condition. In particular, a particularly short duration of individual or all movements can be sought. Next, a particularly low energy consumption be sought, especially in those movements that are not critical to the production performance of the entire production plant. It may also be thought to require low noise, for example, when moving products that are prone to rattling.

It can be provided that the conditions for the movements to be executed are determined automatically. Furthermore, it can be provided that previously determined abstract conditions are used to automatically determine the conditions.

It is understood that the features mentioned above and those yet to be explained below can be used not only in the particular combination indicated, but also in other combinations or in isolation, without departing from the scope of the present invention.

• 1 eine grobschematische Draufsicht eines erfindungsgemäßen Planarantriebs.

The invention will be explained in more detail below with reference to the accompanying drawings. It shows:

• 1 a rough schematic plan view of a planar drive according to the invention.

1 shows a rough schematic plan view of a planar drive according to the invention 10 , The planar drive 10 includes a stator 11 which is substantially rectangular in shape, along an X and a Y axis 12 ; 13 extends, which are aligned perpendicular to each other. The stator 11 For example, it includes a plurality of elongate coils (not shown) that extend selectively along the X or Y axis 12 ; 13 extend. The movers 20 ; 21 ; 22 are typically square in shape, being provided at the bottom with permanently arranged permanent magnets. By suitable energization of said coils, the movers 20 ; 21 ; 22 be kept static in the balance. But it's also possible the movers 20 ; 21 ; 22 along any path in the XY plane of the stator 11 to move. A corresponding planar drive is for example from the US 9 685 849 B2 the entire contents of which are referred to and incorporated in the content of the present application. Other planar drives with the same functionality but different structure are out US 6 003 230 A1 . US Pat. No. 6,069,418 A1 . US Pat. No. 6,097,114 A1 . US Pat. No. 6,441,514 B1 . US Pat. No. 6,452,292 B1 . US Pat. No. 6,987,335 B2 . US Pat. No. 7,057,370 B2 . US Pat. No. 7,224,252 B2 and US Pat. No. 7,948,122 B2 known. In the German patent application with the file number 10 2016 224 951.7 a planar drive is also described, the stator is provided with rotatable permanent magnets, which are each driven by an electric motor. At the bottom of the mover permanent magnets are firmly attached. Also for this planar drive, the present invention is usable.

The planar drive 10 is part of an industrial production plant 16 that have multiple processing stations 40 includes, with the term process station is common. In the processing stations 40 become workpieces, products or objects, which with movers 20 ; 21 ; 22 be transported, processed, which is intended in particular to assembly operations and / or test procedures. Several similar processing stations 40 are to groups 41 ; 42 summarized. These processing stations typically include a slow-running machining process that needs to be performed multiple times in parallel to allow all machining processes to run at about the same time-based throughput.

The movers 20 ; 21 ; 22 With the workpieces can be moved almost anywhere between the processing stations back and forth. Accordingly, the processing stations 40 largely arbitrary on the stator 11 be distributed, with their position during the machining process typically does not change. As part of a plant conversion, it is conceivable that processing stations 40 be exchanged or moved. Furthermore, it is conceivable to have a multiplicity of processing stations 40 to withhold a multitude of different manufacturing processes with the production plant 16 can be executed, wherein during a specific manufacturing process, only a part of the processing station 40 is used. As a result, with such a production facility 16 a very large number of different products are produced, in particular small batches and in extreme cases only a single copy of a product can be produced efficiently.

In the context of such a flexible production process, however, the problem arises that the movements of the movers 20 ; 21 ; 22 must be set between the processing stations according to the desired production process. The advantage of the present invention is that this can be done largely automated. First of all, the abstract conditions described at the outset are defined, which always apply irrespective of the actual production process desired. The abstract conditions depend in particular on which processing stations are present and how they are positioned relative to the stator. Furthermore, the abstract conditions depend on which product range with the actual production plant 16 to be produced.

During the current production process, for example, the in 1 shown arrangement of movers 20 ; 21 ; 22 , The first and the second mover 21 ; 22 are here with solid lines in the starting point 30 the shown desired movement. Dashed lines indicate the desired endpoint 31 shown the movement. The movers 20 ; 21 ; 22 can be assigned specific characteristics. In particular, it is intended to assign the mover the specific serial number, the concrete construction variant and the concrete state within the manufacturing sequence. In 1 for example, should the first movers 21 just be loaded with a raw blank, wherein the machining of the workpiece on the second mover 22 in the corresponding processing station 40 just finished.

From the mentioned concrete features of the first movers 21 , in particular the state within the production sequence, results in the present example, that this in one of the processing stations 40 the group 41 to move, since there the next processing step is carried out. As one of these processing stations 40 is occupied, only the other remains as an endpoint 31 , Had the group 41 more blank processing stations 40 , would in the context of path planning multiple endpoints 31 using the best endpoint in terms of shortest possible production time 31 would be selected. This corresponds to one of the abstract conditions explained above. The destination processing station 40 in front of the second mover 22 is still present in the present case, which is why the endpoint 31 so in front of the processing station 40 is arranged that later a quick change of the mover in said processing station 40 is possible.

In the context of the automated selection of the movement sequence, preferably a movement path is first 50 established. First and foremost is a straight trajectory 50 aspired, as is the case for the second mover 22 is shown. At the first mover 21 is the straight path of movement through a workstation 40 obstructed, which is why a curved trajectory 50 is selected, for example, the shortest path of movement, in which there is no collision with a processing station 40 and does not result in crossing over a forbidden area of the stator.

Before carrying out the movements, it is checked which concrete conditions have to be met. For this, the abstract conditions are combined with the concrete features of the present objects (such as movers, products, process stations, ...); this results in concrete conditions. In the example, it is assumed that the product type of the product is on movers 22 Linked to the abstract condition is that each product of this type must meet a certain minimum distance to any other product. This results in a concrete, mathematically describable condition for the trajectories to be determined 50 in space and time. This condition can be passed to a suitable algorithm for path calculation from industrial robotics. The abstractly formulated conditions are thus adhered to for the specific case, without the concrete movements being known in advance.

The inventive method is preferably by a control device 15 executed, to which the stator 11 and an associated position detection device 14 are connected ,. wherein the position detecting device 14 in the stator 11 can be integrated. The control device 15 preferably comprises a program-controlled digital computer.

LIST OF REFERENCE NUMBERS

10

planar drive

11

stator

12

X axis

13

Y-axis

14

Position detection device

15

control device

16

plant

20

Mover

21

first mover

22

second mover

30

starting point

31

endpoint

40

processing station

41

Group of workstations

42

Group of workstations

50

trajectory

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• US 9685849 B2 [0002, 0024]
• DE 102014212256 A1 [0002]
• US6003230A1 [0024]
• US 6069418 A1 [0024]
• US 6097114 A1 [0024]
• US Pat. No. 6441514 B1 [0024]
• US Pat. No. 6,622,292 B1 [0024]
• US Pat. No. 6,883,735 B2
• US 7057370 B2 [0024]
• US 7224252 B2 [0024]
• US 7948122 B2 [0024]

Claims (12)

Method for operating a planar drive (10), preferably in the context of an industrial production plant, wherein the planar drive (10) comprises a stator and at least one mover (20, 21, 22), each mover (20, 21, 22) being at least two linear degrees of freedom (12; 13) being movable with respect to the stator (11), whereby it can be driven correspondingly by the stator (11), at least one position detecting device (14) being provided, with which the position of each mover (20; 21; 22) relative to the stator (11) can be determined, characterized in that at least one condition is given, which during a movement of the at least one mover (20; 21; 22) is to be maintained relative to the stator (11), wherein the at least one mover a first Mover (21), wherein a start and at least one end point (30; 31) of a movement of the first mover (21) are predetermined, wherein a movement sequence of the first mover (21) between the beginning and the at least one End point (30; 31) is automatically selected so that the at least one condition is met, reaching an end point (31), wherein the first mover (21) is moved using the stator (11) and the position detecting device according to the selected course of motion. Method according to Claim 1 wherein the movement sequence comprises a geometric movement path (50) along which the movement of the relevant mover (21; 22) extends, wherein the movement sequence further comprises the time sequence of the movement along the movement path (50). Method according to Claim 2 , wherein the trajectory (50) and the timing are selected sequentially automated. The method of claim 1, wherein the at least one mover comprises a second mover different from the first, wherein a first condition for the first mover comprises the selected mover for the second mover, wherein the first condition that the first and the second mover (21; 22) do not collide during a movement corresponding to the selected movement sequence. Method according to Claim 4 , wherein the movement sequence of the second mover (22) is selected again if the first condition of the first mover (21) can not be maintained with the previously selected movement sequence of the second mover (22). Method according to Claim 4 or 5 , wherein at least three movers (20; 21; 22) are present, wherein a condition corresponding to the first condition is specified for all possible pairs of movers (20; 21; 22). Method according to one of the preceding claims, wherein a second condition of a mover (20; 21; 22) comprises permissible positions and / or the maximum permissible movement speed and / or the maximum permissible movement acceleration and / or the maximum movement pressure of this mover. Method according to one of the preceding claims, wherein a mover (20; 21; 22) is not moved when its mass exceeds a predetermined maximum mass. Method according to Claim 8 wherein the actual mass of a mover (20; 21; 22) is determined using the bearing detection device (14). Method according to one of the preceding claims, wherein at least one condition comprises the optimization of a physical parameter of the planar drive (10) or the production facility (16). Method according to one of the preceding claims, wherein the conditions are automatically determined to the executed movements. Method according to Claim 11 , where previously determined abstract conditions are used to automatically determine the conditions.

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