Method of controlling an intralogistic conveyor arrangement

Abstract

Method of operating an intralogistic conveyor arrangement (1), adapted to convey an object (9) in a downstream conveying direction (d), the conveyor arrangement (1) comprising a plurality of conveyor branches (10,20,30) each conveyor branch having a plurality of conveyor zones (12,22,32), each conveyor zone (2) is adapted to convey an object (9) from an inlet (I) of said conveyor zone (12,22,32) to an outlet (O) of said conveyor zone (12,22,32), a first conveyor branch (10) of first branch conveyor zones (12) and a second conveyor branch (20) of second branch conveyor zones (22) merge at a merging zone (12a,22a) into a third conveyor branch (30), wherein the said first conveyor branch (10) and said second conveyor branch (20) merge at a at least one merging zone (12a, 22a) into the third conveyor branch (30); wherein the Intralogistic conveyor arrangement is operated in a manner, so that a collision is prevented between objects (9a, 9d, 9f) transferred from the first conveyor branch (10) into the third conveyor branch (30) and objects (9b, 9c, 9e) transferred from the second conveyor branch (20) into the third conveyor branch (30) and vice versa; wherein for avoiding said collision, the speed of said objects (9a,9d,9f) moving at least in one of said first conveyor branch (10) and second conveyor branch (20) is selectively reduced or increased.

Description

[0001] Method of controlling an intralogistic conveyor arrangement description

[0002] The invention refers to method of controlling an intralogistic conveyor arrangement;

[0003] Conventionally intralogistic conveyor arrangements comprises a plurality of conveyor zones, wherein the operation of the conveyor zones are operated in a manner, so that collision of conveyed objects are prevented. Therefore, objects are selectively stopped to prevent collision.

[0004] This also applies at merge situations, where two separate branches of conveyor zones are merged into one single branch.

[0005] Stopping of objects causes always a drawback in the overall conveying capacities. European patent application EP23213748.9 (not published yet) discloses a conveyor arrangement, where the speed of object in one branch is adjusted to optimize the efficient flow of objects.

[0006] WO 2009 / 0242 98 A1 and US 5,341 ,916 A discloses a method of conveying objects from two conveyor branches to a common merge point. The speed of the objects is controlled in a manner so as to avoid a collision of the said objects at the merge. The speed is controlled for all conveyors in the branches by a central controller.

[0007] It is the object of the present invention to optimize the flow of objects in a conveyor arrangement at merge situations.

[0008] The invention is solved by a method and an intralogistic conveyor arrangement according to the main claims; embodiments are subject to the subclaims and the description.

[0009] According to the invention, for avoiding a collision during at the merge positions (that is where the first branch meets the second branch of conveyor zones), the speed of said objects moving at least in one of said first conveyor branch 10 and second conveyor branch 20 is selectively reduced or increased (adjustment of speed).

[0010] Due to the early speed adjustment, stopping of the objects can be avoided, which leads to an optimized flow of objects. The effect of overall conveying performance, e.g. measured in “objects passing the merging position per time” can be increased compared to the conventional solution.

[0011] In particular the speed is therefore adjusted already at conveyor zone at least tow zone upstream of the merge positions. The earlier the adjustments of speed are performed, the smaller the individual changes will be in terms of amount. In an embodiment the speed of one of a plurality of objects moving at least in one of said first branch and second conveyor branch is selectively reduced or increased; this means, that a the speed of neighbored objects located in the same branch may be different. In other words: there is no common branch speed valid for the complete branch, which will be amended at once.

[0012] In an embodiment the selective adjustment of speed of objects is controlled by a plurality of controllers. Therefore the local controllers coordinate with each other, which of the moving objects is to be accelerated or decelerated. The data required for coordination is there kept local at the zone controller, without the necessity to involve one central PLC.

[0013] In particular the at least one first branch zone controller and the at least one second branch zone controller are adapted to coordinate with each other the adjustment of object’s speed for the matter of collision avoiding within the first and second conveyor branches (10, 20) without involving a central control.

[0014] In general said is considered as a speed where the object is actually conveyed. Therefore when talking about adjustment of the speed it means the a speed at a level different to different Zero is meant. Just stopping an object is not considered as adjusting the speed.

[0015] A non-limiting example of the invention is described with respect to the figures; herein show fig. 1 an exemplary conveyor zone used within the invention; fig. 2 to 9 schematically a conventional conveyor arrangement where two conveyor branches join each other at a merge location to a common merged branch along with speed diagrams of conveyed objects. fig. 10 to 17 schematically an inventive conveyor arrangement where two conveyor branches join each other at a merge location to a common merged branch along with speed diagrams of conveyed objects.

[0016] Figure 1 shows an exemplary conveyor zone 12,22,32, comprising several conveyor rollers 3 which are driven together. For this purpose, one of the conveyor rollers is designed as a motorized conveyor roller 3M. The motorized conveyor roller 3M is driven in particular by a three-phase motor arranged within in the conveyor roller 3M. Via one or more drive connectors 4, e.g. a drive belt, the conveyor rollers 3 of a conveyor zone 12,22,32 are drive-connected to each other and are jointly driven by the motor-driven conveyor roller 3M. An object 9 is linearly conveyed from an inlet I to an outlet O. In the embodiment shown here the conveyor rollers establish a conveyor surface on which the object is supported. In another embodiment also according to the invention, a conveyor belt may be provided, on top of which the object is supported.

[0017] By means of a presence sensor 5, the presence of a conveyed object 9 arranged the conveyor zone 12,22,32 can be determined. The presence sensor 5 does not have to cover the entire conveyor zone 12,22,32; it is sufficient if the presence of a conveyed object 9 within a partial area of the conveyor zone 12,22,32 is detected by the presence sensor 5. The presence sensor 5 thereby generates a sensor signal S5, which is connected via a signal line (not shown) to a conveyor zone controller 11 ,21 ,31 presented further below. Presence detection can also be performed without an explicit sensor and can be derived from other raw data. For example, there are already approaches to derive the presence of a conveyed object 9 on the conveyor zone 12,22,32 from other data, e.g. from the course of the current intensity in a conveyor zone 12,22,32.

[0018] In particular the presence sensor 5 is adapted to detect a time, when a leading edge 91 of the object 9 is entering the area of detection of the presence sensor 5. By combining this time with the rotational speed of the rollers 3, 3M and a length L of the conveyor zone 12,22,32, the position of the object 9 along the conveyor zones 12,22,32 can be continuously tracked over the time. Accordingly, it is not required, that each conveyor zone 12,22,32 has its own presence sensor 5; however, by increasing the density of presence sensors 5 within a conveyor arrangement 1 , the accuracy of continuous object 9 tracking can be increased.

[0019] The conveyor rollers 3 and the presence sensor 5 are attached to a common support frame 8. The conveyor rollers 3 of several conveyor zones 12,22,32 can be attached to a common support frame 8.

[0020] The motor-driven conveyor rollers 3M are each controlled by at least one or a plurality of conveyor zone controller(s) 11 ,21 ,31 . A single conveyor zone controller 11 ,21 ,31 can control the motor-driven conveyor rollers 3M of several conveyor zones 12,22,32. Several such conveyor zone controllers 11 ,21 ,31 are arranged in a conveyor arrangement 1 which communicate with each other via a data bus connection 13. The conveyor zone controller 11 ,21 ,31 may be incorporated into one of the rollers 3, 3M.

[0021] Figures 2 to 9 show a conventional conveyor arrangement 1 , where a first conveyor branch 10 of conveyor zones 12 and a second conveyor branch 20 of conveyor zones 22 are merged together into a merged third conveyor branch 30 of conveyor zones 32. The conveyor zones 12, 22 of the first and second conveyor branches 10, 20 are occupied in a random manner by individual objects 9a... f. In a “Flip book” manner the figures 2 to 9 show the conveying operation of the conveyor arrangement until all objects have entered the third merged branch 30.

[0022] During merging, only one object 9 enters the merging area, so that the objects does not collide.

[0023] First and second objects 9a, 9b enter the merging zones 12a, 22a sequentially, so that both objects 9a, 9b can continue to travel at a constant speed (see figures 2 to 5) without the need to stop one of said objects 9a, 9b.

[0024] Third and fourth objects 9c, 9d are arranged on the first and second conveyor branch 10, 20 in a manner so that these objects 9c, 9d would enter the merging zones 12a, 22a in a colliding manner (see figure 5). To avoid collision, one of said objects 9c, 9d, here the fourth object 9d is stopped, priority to enter the merging zones 12a, 22a was given to the third object 9c (figure 6). As soon as third object 9c has left the merging zones 12a, 22a, the fourth object 9d enters the merging zone 12a, 22a (figure 7).

[0025] Same applies to the fifth and sixth objects 9e, 9f which are arranged on the first and second conveyor branch 10, 20 in a manner so that these objects 9e, 9f would enter the merging zones 12a, 22a in a colliding manner (see figure 7). To avoid collision, one of said object 9e, 9f, here the sixth object 9f is stopped, priority to enter the merging zones 12a, 22a was given to the fifth object 9e (figure 8). As soon as the fifth object 9e has left the merging zones 12a, 22a, the sixth object 9f enters the merging zones 12a, 22a (figure 9).

[0026] Even if the capacity of the third branch would allow to convey the number of the objects 9 conveyed in the third conveyor branch 30, it becomes visible from the figures that a gap G1 is generated in the flow of objects 9 in the third merged conveyor branch 30 (see figures 5 to 7).

[0027] Figures 10 to 17 show an inventive conveyor arrangement 1 during operation, where a first conveyor branch 10 of conveyor zone 12 and a second conveyor branch 20 of conveyor zones 22 are merged to together into a merged third conveyor branch 30 of conveyor zones 32. For reason of easy comparison the starting situation of objects in figure 10 is similar to the situation of figure 2.

[0028] The conveyor zones 12, 22 of the first and second conveyor branches 10, 20 are occupied in a random manner by individual objects 9a...f. In a “Flip book” manner the figures 10 to 17 show the conveying operation of the conveyor arrangement 1 until all objects 9 have entered the third merged conveyor branch 30. During merging, maximum one object 9 is allowed to enter into the merging zones 12a, 22a.

[0029] First and second objects 9a, 9b enter the merging zones 12a, 22a sequentially, so that both objects 9a, 9b can continue to travel at a constant speed (see figures 10 to 13) without the need to stop one of the said objects 9a, 9b.

[0030] Third and fourth objects 9c, 9d are arranged on the first and second conveyor branch 10, 20 in a manner so that these objects 9c, 9d would enter the merging zones 12a, 22a in a colliding manner (similar to figure 5). To avoid collision, one of said objects 9c, 9d, here the fourth object 9d, is accelerated at an early stage and driven for a certain time at a higher speed, to enter into a gap G2 located downstream of the fourth object 9d (see figures 10 to 12).

[0031] This leads to the result, that the third and fourth objects 9c, 9d do not enter the merging zones in a colliding manner and that a third object 9c can enter the merging zones12a, 22a before fourth object 9d without the need to stop any of the said objects.

[0032] Same applies to the fifth and sixth objects 9e, 9f which are arranged on the first and second conveyor branch 10, 20 in a manner so that these objects 9e, 9f would enter the merging zones 12a, 22a in a colliding manner (see figure 15), when conveyed at constant speeds. To avoid collision, one of said objects 9e, 9f, here the sixth object 9f is accelerated at an early stage to enter into a gap G3 located downstream of the sixth object 9f (see figures 10 to 12).

[0033] Since the fourth object 9denters into the gap G2 at an early stage, there remains no gap G1 in the third conveyor branch 30 compared to the situation of the conventional conveyor arrangement 1 (see figures 5 to 7).

[0034] The objects in total are conveyed faster into the third conveyor branch 30, which becomes visible by the comparison of figures 9 and 17. In figure 9, situation VIII, the last object 9f is located on the merging zones 12a, 22a, where in figure 17, situation VIII, the last object 9e is located one zone more downstream in zone 32z of third conveyor branch 30.

[0035] The inventive method is controlled merely by plurality of the conveyor zone controllers 11 ,21 ,31 . Thereby the first branch zone controllers 11 of the first conveyor branch 10 are in data communication via the data bus connection 13 with the second branch zone controllers 21 of the second conveyor branch 20. The different zone controller 11 , 21 of different conveyor branches 10, 20 exchange information about the position and speeds of objects and allocate priorities to individual objects. As a consequence, there is not central control involved in the controlling the speeds of the objects during merging in the third conveyor branch. The direct communication paths C via the data bus connection 13 are exemplarily depicted in figure 10. Ommitting a central control leads to faster data communication and faster response times, leading finally to a smoother merging process with at the end smaller speed deviations and corrections.

[0036] List of reference signs

[0037] 1 conveyor arrangement

[0038] 3 conveyor roller

[0039] 3M motorized roller

[0040] 4 connector

[0041] 5 presence sensor

[0042] 8 support frame

[0043] 9 object

[0044] 10 first conveyor branch

[0045] 11 first branch zone controller

[0046] 12 first branch conveyor zone

[0047] 13 data bus connection

[0048] 20 second conveyor branch

[0049] 21 second branch zone controller

[0050] 22 second branch conveyor zone

[0051] 30 third I merged conveyor branch

[0052] 31 third branch zone controller

[0053] 32 third branch conveyor zone d conveying direction

[0054] G gap

[0055] I inlet of conveyor zone

[0056] O outlet of conveyor zone

[0057] L length of conveyor zone

[0058] S5 sensor signal

[0059] C direct communication path via bus

Claims

Claims1. Method of operating an intralogistic conveyor arrangement (1), adapted to convey an object (9) in a downstream conveying direction (d), the conveyor arrangement (1) comprising a plurality of conveyor branches (10,20,30) each conveyor branch having a plurality of conveyor zones (12,22,32), each conveyor zone (2) is adapted to convey an object (9) from an inlet (I) of said conveyor zone (12,22,32) to an outlet (O) of said conveyor zone (12,22,32), a first conveyor branch (10) of first branch conveyor zones (12) and a second conveyor branch (20) of second branch conveyor zones (22) merge at a merging zone (12a, 22a) into a third conveyor branch (30), wherein the said first conveyor branch (10) and said second conveyor branch (20) merge at a at least one merging zone (12a, 22a) into the third conveyor branch (30); wherein the Intralogistic conveyor arrangement is operated in a manner, so that a collision is prevented between objects (9a, 9d, 9f) transferred from the first conveyor branch (10) into the third conveyor branch (30) and objects (9b, 9c, 9e) transferred from the second conveyor branch (20) into the third conveyor branch (30) and vice versa; characterized in that for avoiding said collision, the speed of said objects (9a,9d,9f) moving at least in one of said first conveyor branch (10) and second conveyor branch (20) is selectively reduced or increased.

2. Method according to the preceding claim, characterized in that the speed of one of a plurality of objects (9a,9d,9f) moving at least in one of said first conveyor branch (10) and second conveyor branch (20) is selectively reduced or increased; in particular that the objects located in different zones of one branch are moved at different speeds.

3. Method according to any of the preceding claims, characterized inthat the operation of the plurality conveyor zones (12,22,32) are is controlled by a plurality of zone controllers (11) which are adapted to interact which each other so as to individually adjust a conveying speed (v) of said objects moving within the conveyor zones (12,22,32).

4. Method according to the preceding claim, characterized in that said first branch conveyor zones (12) are controlled by at least one first branch zone controller (11); that said second branch conveyor zones (22) are controlled by at least one second branch zone controller (21), and wherein said at least one first branch zone controller (11) is separate to said at least one second branch zone controllers (21).

5. Method according to the preceding claim, characterized in that the first branch zone controllers (11) and the second branch zone controller (21) coordinate with each other the adjustment of object’s speed for the matter of collision avoiding within the first and second conveyor branches (10, 20) without involving a central control.

6. Method according to any of the preceding claims, characterized in that for avoiding said collision the speed is adjusted already at conveyor zone at least two, three and / or four zones upstream of the merge positions.

7. Method according to any of the preceding claims, characterized in that the position of the object (9) along the conveyor zones (12,22,32) is continuously tracked over the time.

8. Intralogistic conveyor arrangement (1), adapted to convey an object (9) in a downstream conveying direction (d), the conveyor arrangement (1) comprising a plurality of conveyor branches (10,20,30) each conveyor branch having a plurality of conveyor zones (12,22,32), each conveyor zone (2) is adapted to convey an object (9) from an inlet (I) of said conveyor zone (12,22,32) to an outlet (O) of said conveyor zone (12,22,32),a first conveyor branch (10) of first branch conveyor zones (12) and a second conveyor branch (20) of second branch conveyor zones (22) merge at a merging zone (12a, 22a) into a third conveyor branch (30), wherein the said first conveyor branch (10) and said second conveyor branch (20) merge at a at least one merging zone (12a, 22a) into the third conveyor branch (30); a plurality of zone controller adapted to control the operation of the conveyor zones in a manner, so that objects (9a, 9d, 9f) transferred from the first conveyor branch (10) into the third conveyor branch (30) are not colliding with objects (9b, 9c, 9e) transferred from the second conveyor branch (20) into the third conveyor branch (30) and vice versa; characterized in that said zone controller are adapted to control the conveyor zones in a manner, that for avoiding said collision, the speed of said objects (9a,9d,9f) moving at least in one of said first conveyor branch (10) and second conveyor branch (20) is selectively reduced on increased.

9. Intralogistic conveyor arrangement (1) according to the preceding claim, characterized by a plurality of zone controllers (11) adapted to control the operation of the plurality conveyor zones (12,22,32), wherein the zone controllers adapted to interact which each other so as to individually adjust a conveying speed (v) of said objects moving within the conveyor zones (12,22,32) of different branches of conveyor zones.

10. Intralogistic conveyor arrangement (1) according to claim 8 or 9, characterized by at least one first branch zone controller (11) controlling the operation of the first branch conveyor zones (12), and at least one second branch zone controller (21) controlling the operation of the second branch conveyor zones (22), and wherein the at least one first branch zone controller (11) is separate to the at least one second branch zone controller (21) andand wherein the at least one first branch zone controller (11) and the at least one second branch zone controller (21) are adapted to coordinate with each other the adjustment of object’s speed for the matter of collision avoiding within the first and second conveyor branches (10, 20) without involving a central control.

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