METHOD FOR OPERATING A TRANSPORT SYSTEM AND TRANSPORT SYSTEM

Description

[0001] The invention relates to a method for operating a transport system, in particular a multi-carrier system, comprising a plurality of linear motors arranged in a row and having a guide track, a plurality of transport elements movable along the guide track by means of the linear motors, and a plurality of stations along the guide track, wherein each of the transport elements is assigned to one of the stations. Furthermore, the invention relates to a transport system, in particular a multi-carrier system, having a control unit configured to carry out the method.

[0002] The provision of stations along the guideway or route of a transport system is generally known. Such stations are possible starting and destination points for transport elements. Certain actions are often performed at these stations. For example, transport elements can be loaded or unloaded with a product at these stations.

[0003] Typically, each station is assigned a waiting position upstream along the route. When a transport element is to be sent to the next station, it receives a travel order to the corresponding waiting position. Only when it arrives at the waiting position and stops there does the receiving station take over and checks whether it is already occupied by another transport element. Only when the station is free is the transport element given permission to advance to the actual station. However, this also means that the transport element will stop briefly in the waiting position even if the station is already free when the transport element arrives at the waiting position. In addition, transport elements are stopped in a station or their waiting position even if they have a travel order to a downstream station. The (upstream) station determines this and only then hands the transport element over to the next (downstream) station.

[0004] Such transfer points have so far been necessary to ensure the orderly transfer of a transport element from one station to the next station, so that each station knows the transport elements assigned to it. For this purpose, each station must also have available memory that corresponds to the maximum number of all transport elements on the route, since each station must be set up to manage all transport elements simultaneously. When handed over to a station, the respective transport element is noted in the memory and removed from the memory of the previous station. However, the storage of the transport elements or their indices is unstructured, so additional measures must be taken to be able to trace the order of the transport elements assigned to the station along the route so that the correct transport elements are addressed. This is complex and requires additional memory.

[0005] Furthermore, the potentially multiple and sometimes unnecessary stops of transport elements during the journey are purely due to organizational considerations and should ideally be avoided. The resulting delays increase the more stations are planned along the route.

[0006] EP 3 974 927 A1 discloses a linear motor system with multiple transport elements and a control system. This system includes a memory with a reference array that refers to specific elements of the linear motor system, such as transport elements, and points to memory addresses where certain properties of these elements are stored, such as speed or acceleration. The control system uses the stored properties to generate control commands and send them to the respective transport elements.

[0007] It is an object of the present invention to provide a method for operating a transport system and a transport system with improved handling of transport elements.

[0008] This problem is solved by the subject matter of the independent claims. Advantageous embodiments are the subject matter of the subclaims and emerge from the description and the drawings.

[0009] The method according to the invention serves to operate a transport system, in particular a multi-carrier system, wherein the transport system comprises a plurality of linear motors arranged in a row and having a guide track, a plurality of transport elements movable along the guide track by means of the linear motors, and a plurality of stations along the guide track, and wherein each of the transport elements is assigned to one of the stations. The method comprises the following steps: Creating an instance for each of the transport elements, Creating a list for each of the stations, wherein the instance for each transport element assigned to the respective station is assigned to the list, and wherein within the respective list the instance of each transport element is linked to the instance of the transport element immediately before and to the instance of the transport element immediately after the transport element in question, Transferring a transport element from a first station to an immediately subsequent second station and inserting the instance of this transport element into the list of the second station if there is a travel order for the transport element that goes beyond the first station, wherein the transfer of the instance is event-controlled and independent of a transfer point if a predetermined transfer condition is met, and Controlling the linear motors in order to execute travel orders of the transport elements.

[0010] Each linear motor can, in particular, have six outer surfaces: a top surface, a bottom surface, an outer surface, an inner surface, and two side surfaces. The side surfaces of adjacent linear motors are spaced apart from each other by a small expansion gap of approximately 0.1 mm to 0.2 mm, or they are in direct contact with each other. The guideway for the transport elements can be formed on the outer surface. The inner surface is arranged in the region of an interior space of the transport system.

[0011] The transport system or multi-carrier system can be designed to be continuous, so that the linear motors form a self-contained guideway along which the transport element or elements can theoretically be moved endlessly in the same direction. However, it is also possible for the linear motors to form an open guideway with a starting point and an end point. Several stations are arranged along the guideway, but these stations usually only exist virtually and are defined, for example, by a coordinate of the guideway. Such stations are possible starting and destination points for transport elements. For example, a transport element can receive a travel command that allows it to travel from one station to another, which corresponds to a section of the guideway.Actions can also be performed at the stations, such as loading or unloading the transport element with a product or coupling or uncoupling a certain number of consecutive transport elements.

[0012] The transport elements are, in particular, magnetically driven. For this purpose, the transport elements have one or more permanent magnets, which are subjected to a driving force by means of a changing and / or moving magnetic field generated by the linear motors. This driving force causes the transport elements to move along the guideway. In particular, the transport elements can be moved independently and separately from one another. This allows workpieces or products, for example, to be transported along the guideway using the transport elements.

[0013] To hold the transport elements on the guideway, they are preferably attracted to the guideway by an attractive force in a direction perpendicular to the direction of movement of the transport element. Thus, the attractive force also runs perpendicular to the drive force. The attractive force preferably runs from the guideway to the linear motors or to the coils of the linear motor. The attractive force is usually generated by the magnet of the transport element being attracted to a magnetically conductive stator of the respective linear motor.

[0014] The transport element can also be called a carrier, mover or runner, while the linear motor can also be called a stator.

[0015] Creating an instance for each transport element means that each transport element located on the route or guideway is assigned a virtual image, with the instances preferably being identically structured. A pool of instances is created, so to speak, so that exactly one instance exists for each transport element. Each transport element, and thus each instance, is assigned to exactly one of the stations. The transport element or instance can also be transferred, for example, from one station to the next station along the guideway.

[0016] Each station is also assigned the list of instances currently assigned to the station. Because the instance of each transport element is linked within the respective list to the instance of the transport element immediately before and to the instance of the transport element immediately after the transport element in question, the station knows the order of the transport elements assigned to it. Additional management of the order of the transport elements assigned to the station along the route is therefore unnecessary because, thanks to the list or chain, the station always knows the first list element, which corresponds to the foremost transport element in the direction of movement. In particular, the station always assigns the next travel order to the first element in the list or chain that is linked to this foremost transport element, in particular referring to its index.

[0017] For the instance of the frontmost transport element in the direction of travel that is assigned to the station, i.e. the first instance in the list, the link to the front instance is preferably marked as a link to empty space, for example, as a NULL reference. The same applies to the instance of the last transport element in the direction of travel that is assigned to the station, i.e. the last instance in the list. In this case, the link to the rear instance is preferably marked as a link to empty space. This makes it possible to determine for each station which transport elements are assigned to it, in which order they are arranged, and which is the first and which is the last transport element in the direction of movement that is assigned to the station.Since exactly one instance is created for each transport element globally and not every station has to maintain sufficient memory for the maximum number of transport elements on the route, significant memory savings can be achieved.

[0018] Whenever we refer to transport elements "ahead," "in front of," "before," or "behind" the transport element in question, this refers to the direction of movement. The transport element "ahead" or "before" thus refers to a transport element that is moving ahead in the direction of movement, while the transport element "behind" the transport element in question refers to a transport element that follows the transport element in the same direction. Accordingly, a "following" (second) station refers to a station downstream of the (first) station in question in the direction of movement.

[0019] If the term "immediate" is used in connection with transport elements or stations, it does not imply any statement about temporal or spatial distances, but means that there are no further stations or transport elements between the corresponding stations or transport elements.

[0020] When a transport element is passed from one station to a subsequent station, the corresponding instance of this transport element is inserted into the list of the second station, i.e., appended to the last position of the list. Accordingly, the instance is removed from the list of the preceding station upon transfer. With the transfer, the responsibility for the transport element preferably changes between the stations, allowing them to execute commands for the transport element.

[0021] The handover is event-controlled and independent of a handover point (i.e. a particularly predetermined point or section on the guideway that can be approached or occupied by a transport element), also known as a trigger point. This means that there is no need for a defined handover point, such as a waiting position to which the transport element must first be moved. Instead, the transport element can be handed over in an event-based manner, with the respective handover event being almost freely definable. This means that the station to which the transport element is handed over can check, if necessary before the transport element arrives, whether the transport element must stop in front of the station because it is occupied, or whether it can enter the station directly.If the transport element executes a travel order to a further downstream station, this order can also be immediately forwarded to the next station, even before the transport element arrives. This eliminates unnecessary stopping in a waiting position and unnecessary waiting at a station that is not the destination of the transport element.

[0022] In a preferred embodiment, the transfer condition is met when the transport element has started moving and / or has reached a predetermined transfer speed. In particular, the transport element can be transferred to the next station immediately after it has started moving. Therefore, there is no need to wait until the transport element arrives at a waiting position. Rather, the route between two stations can be used to allow the arrival station to check whether the station is currently free or occupied and whether it still needs to transfer the transport element to the next station.

[0023] Preferably, each instance has a link to the instance of the transport element immediately preceding it, a link to the instance of the transport element immediately following the transport element under consideration, and an identification feature for the respective transport element. This allows for a reliable determination of whether there are any preceding or following transport elements assigned to the same station, and which transport element is involved.

[0024] In particular, the links can be implemented as pointers or indicators pointing to memory addresses of the respective instance. Passing an instance from the first station to the immediately following second station can then be accomplished by overwriting (and modifying accordingly) the memory addresses to which the respective pointers point. This represents a particularly efficient and fast way to represent the "passing" of the instance from one list to another.

[0025] More precisely, the instances assigned to the transport elements located at a station can each form a linked list. Each instance can have a pointer to the previous and subsequent instance. The instances of the first and last transport element—on the guideway—can have a null pointer. If the first transport element now moves from a first station to a second station, the pointers are modified such that the instance of the transport element is integrated into the linked list of instances of the second station.

[0026] The transport system can also include a control unit, with a memory area being provided in the control unit for creating instances for each of the transport elements. This creates a global "pool" of instances, in which the instances can be linked via references (e.g., using the aforementioned pointers) in the lists or chains, without each station having to maintain memory for the maximum, theoretically possible number of transport elements.

[0027] The invention also relates to a transport system, in particular a multi-carrier system, comprising a plurality of linear motors arranged in a row and having a guide track, a plurality of transport elements movable along the guide track by means of the linear motors, and a plurality of stations along the guide track. Furthermore, the transport system comprises a control unit configured to carry out the method according to the invention.

[0028] In the transport system, the stations can be arranged at least partially at identical positions along the guideway. Since no hardware transfer points or trigger points are required, stations can be defined purely virtually by their position or coordinate along the guideway. This also means that different stations can be defined at the same position or coordinate, which can then, for example, fulfill different functions.

[0029] Furthermore, the statements made regarding the method according to the invention apply accordingly to the transport system according to the invention, and vice versa. It is understood that all features and embodiments mentioned herein can be combined with one another, unless otherwise stated.

[0030] The invention is described schematically and by way of example below with reference to the drawings, in which: Fig. 1 a plan view of a transport system designed as a multi-carrier system according to an embodiment, Fig. 2 an example of a list of a station to which three transport elements are assigned, Fig. 3 the list from Fig. 2 after the first instance in the list has been passed to a subsequent station, and Fig. 4 the list of the subsequent station after the first instance of the list from Fig. 2 has been handed over to them.

[0031] Fig. 1shows schematically a transport system 10 designed as a multi-carrier system in plan view, which has a plurality of linear motors 11, which in the present embodiment are arranged in a closed row and form a closed guideway 13 for transport elements 15, 17, 19. For an illustrative description, in Fig. 1Only three transport elements 15, 17, 19 are shown, namely a first transport element 15, a second transport element 17, which is located directly in front of the first transport element 15 in the direction of movement x, and a third transport element 19, which is located directly behind the first transport element 15 in the direction of movement x. "Directly" is not to be understood as referring to a specific distance between the respective transport elements 15, 17, 19, but rather means that there is no further transport element between immediately successive transport elements 15, 17, 19.

[0032] The transport elements 15, 17, 19 are magnetically driven by the linear motors 11. For this purpose, the transport elements 15, 17, 19 have one or more permanent magnets (not shown), which are subjected to a driving force by means of a changing and / or moving magnetic field generated by the linear motors 11. The driving force results in a movement of the transport elements 15, 17, 19 along the guide track 13. In particular, the transport elements 15, 17, 19 can be moved independently and separately from one another. The linear motors 11 are controlled by a control unit (not shown) to drive the respective transport elements 15, 17, 19.

[0033] How Fig. 1As can be seen, several stations S 1 , S 2 , S 3 are arranged along the guideway 13, which can be defined, for example, by their position in the direction of movement x along the guideway 13. At the stations, for example, transport elements 15, 17, 19 can be combined or separated again, or pick up a product for transport or deliver it again. For example, the transport elements 15, 17, 19 can receive an instruction from the control unit that moves the respective transport element from station S 1 to station S 2. Such instructions are also referred to as a travel order. Fig. 1Each of the stations S 1 , S 2 , S 3 is arranged at its own position or coordinate along the guideway 13. Alternatively, it is also fundamentally possible for the stations S 1 , S 2 , S 3 , which in the present exemplary embodiment are defined purely virtually by their position or coordinate along the guideway 13, to be arranged completely or partially at identical positions or coordinates, which can then, for example, perform different functions.

[0034] Each of the transport elements 15, 17, 19 on the route is assigned to exactly one of the stations S 1 , S 2 , S 3 at any given time. This means that the respective station S 1 , S 2 , S 3 is responsible for the transport elements 15, 17, 19 assigned to it and can execute commands for the transport elements 15, 17, 19 via the control unit, in particular to stop or drive.

[0035] Fig. 2shows an example of an inventive assignment of three transport elements to a station, where Fig. 2 is to be understood as a purely schematic representation of an exemplary data structure.

[0036] According to the invention, an instance is created for each transport element (also referred to as a carrier, mover, or runner) located on the route. For example, if 20 transport elements are moved on the route, 20 instances are created, so that a corresponding pool with one instance for each transport element exists. This occurs, in particular, in a central memory area of ​​the control unit, which is centrally maintained for the maximum number of transport elements. Fig. 2shows an example of a list L S1 of a station (referred to as "Station 1"). The list L S1 can also be referred to as a chain and contains three instances I 1 , I 2 , I 3 , each of which is assigned to a transport element.

[0037] Each of the instances I 1 , I 2 , I 3 is provided with an identification feature 21, which uniquely identifies the transport element corresponding to the respective instance I 1 , I 2 , I 3 ("Carrier 1", "Carrier 10", "Carrier 9"). In addition, each instance I 1 , I 2 , I 3 has a link 23 to the instance of the transport element immediately ahead and a link 25 to the instance of the transport element immediately behind the transport element in question. The links 23, 25 are designed in particular as pointers, which refer to the memory areas of the respective target elements. If it is the frontmost transport element in the direction of movement x or the last transport element in the direction of movement x that is assigned to the corresponding station, the respective links 23, 25 are marked as a link to nothing, namely here as a null reference, see link 23 of the instance I 1 and link 25 of the instance I 3 .

[0038] With this data structure, the station has an overview of all transport elements assigned to it at any time based on its list, their logical order along the direction of movement x, and, thanks to the null references, also which transport element is the first or last transport element along the direction of movement x that is assigned to the station. This can result in significant memory savings, as there is no need to maintain sufficient memory for the maximum number of transport elements for each station. Instead, a global pool of instances is created, each of which is assigned to a list or chain. Furthermore, additional management of the order of the transport elements assigned to the station along the route is obsolete.The station that will always give the next travel order to the first element of the list or chain that is linked to this foremost transport element can always address the corresponding transport element via the first entry in its list.

[0039] Fig. 3 and 4 illustrate the transfer of a transport element from a station ("Station 1" according to Fig. 3 ) to the station immediately following it in the direction of movement x ("Station 2" according to Fig. 4). Fig. 3 corresponds essentially Fig. 2 , where the Fig. 2The instance I 1 shown, corresponding to the foremost transport element in the direction of movement x assigned to the station, has already been transferred to the next station and has therefore been removed from the list L S1 . Link 23 of instance I 2 has been changed accordingly to a null reference, so that it is clear that "Carrier 10" is the foremost transport element in the direction of movement x currently assigned to "Station 1".

[0040] According to Fig. 4 After the transfer, the list L S2 of the station immediately following in the direction of movement x ("Station 2") contains as its only entry the instance I 1 , which was previously assigned to Station 1. This means that Station 2 is exclusively assigned to Carrier 1. Accordingly, both links 23, 25 are provided with a null reference.

[0041] In an implementation with pointers as links 23, 25, the transfer of the respective instances can be accomplished simply by overwriting the memory addresses to which the respective pointers point, so that the transferred instance is correctly removed from the list or chain of the preceding station and placed in the list or chain of the following station.

[0042] The transfer is event-driven, without the need for separate transfer points, also known as "trigger points." All that is required is a defined transfer condition. This could be, for example, that the transport element has started moving or has reached a certain transfer speed. This makes it possible, for example, for the transport element to be transferred to the next station immediately after starting movement, even if it hasn't yet arrived there. Stopping at a waiting position or transfer position is then unnecessary if the receiving station is free. If the currently executing travel task extends beyond the receiving station and the receiving station is free, it can even transfer the transport element immediately to the next station. The travel time can thus be used to prepare commands for the transport element.Ideally, unnecessary stops for the respective transport element can be avoided.

[0043] The method described here leads to a saving of storage space on the one hand, but also to an improved and simplified handling of transport elements on the route on the other. List of reference symbols

[0044] 10Transport system 11Linear motor 13Guideway 15First transport element 17Second transport element 19Third transport element 21Identification feature 23Link 25Link I 1 Instance I 2 Instance I 3 Instance L S1 List (Station 1) L S2 List (Station 2) S 1 Station S 2 Station S 3 Station xMovement direction

Claims

1. A method for operating a transport system (10), in particular a multi-carrier system, that comprises a plurality of linear motors (11) which are arranged in a row and which have a guide track (13), a plurality of transport elements (15, 17, 19) which can be moved along the guide track (13) by means of the linear motors (11), and a plurality of stations (S1, S2, S3) along the guide track (13), wherein each of the transport elements (15, 17, 19) is associated with one of the stations (S1, S2, S3), and wherein the method has the following steps: - generating an instance (I1, I2, I3) for each of the transport elements (15, 17, 19), - generating a list (LS1, LS2) for each of the stations (S1, S2, S3), wherein the instance (I1, I2, I3) for each of the transport elements (15, 17, 19) associated with the respective station is associated with the list (LS1, LS2), and wherein, within the respective list (LS1, LS2), the instance (I1, I2, I3) of each transport element (15, 17, 19) is linked to the instance (I1, I2, I3) of the transport element (15, 17, 19) directly ahead of the observed transport element (15, 17, 19) and to the instance (I1, I2, I3) of the transport element (15, 17, 19) directly behind the observed transport element (15, 17, 19), - transferring a transport element (15, 17, 19) from a first station to a directly following second station and inserting the instance (I1, I2, I3) of this transport element (15, 17, 19) into the list (LS2) of the second station if a transport job that goes beyond the first station is present for the transport element (15, 17, 19), wherein the transfer takes place in an event-controlled manner and independently of a transfer point if a predetermined transfer condition is fulfilled, and - controlling the linear motors (11) to execute travel jobs of the transport elements (15, 17, 19).

2. A method according to claim 1, characterized in that the transfer condition is fulfilled when the transport element (15, 17, 19) has set off and / or has reached a predetermined transfer speed.

3. A method according to claim 1 or 2, characterized in that each instance (I1, I2, I3) has the link (23) to the instance (I1, I2, I3) of the transport element (15, 17, 19) directly in front of the observed transport element (15, 17, 19), the link (25) to the instance (I1, I2, I3) of the transport element (15, 17, 19) directly behind the observed transport element (15, 17, 19), and an identification feature (21) for the respective transport element (15, 17, 19).

4. A method according to claim 3, characterized in that the links (23, 25) are each configured as pointers referring to memory addresses of the respective instance (I1, I2, I3).

5. A method according to claim 4, characterized in that the transfer of an instance (I1, I2, I3) from the first station to the directly following second station takes place by overwriting the memory addresses to which the respective pointers refer.

6. A method according to any one of the preceding claims, characterized in that the transport system (10) has a control unit and a memory area for creating instances (I1, I2, I3) for each of the transport elements (15, 17, 19) is provided in the control unit.

7. A method according to any one of the preceding claims, characterized in that the stations (S1, S2, S3) are at least partly arranged at identical positions along the guide track (13).

8. A transport system (10), in particular a multi-carrier system, that comprises a plurality of linear motors (11) which are arranged in a row and which have a guide track (13), a plurality of transport elements (15, 17, 19) which can be moved along the guide track (13) by means of the linear motors (11), and a plurality of stations (S1, S2, S3) along the guide track (13), characterized by a control unit which is configured to carry out the method according to any one of the preceding claims.

9. A transport system (10) according to claim 8, characterized in that the stations (S1, S2, S3) are at least partly arranged at identical positions along the guide track (13).