Method of determining a length dimension in a conveyor arrangement

Abstract

Method of determining a length dimension (L, x5) in a conveyor arrangement (1) during installation of the conveyor arrangement, the conveyor arrangement (1) comprising, - a plurality of conveyor zones (2), each conveyor zone is adapted to convey an object (9) from an inlet (I) of said conveyor zone (2) to an outlet (O) of said conveyor zone (2) and each conveyor zone have a constant zone length (L), - each conveyor zones has a zone drive (3M) adapted to provide drive power for conveying the object; - one or a plurality of controllers (11), adapted to control the operation of the respective zone drive (3M) of said conveyor zones (2); - in particular a plurality of presence sensor (5), each adapted to generate a sensor signal (S5, S9) indicating the presence of an object (9) within a conveyor zone (2), wherein said conveyor zones (2) are arranged in a manner, that said object (9) can be transferred from an outlet (O) of a, in particular direct, upstream conveyor zone (2) to an inlet (I) of a downstream conveyor zone (2); the method comprising the following steps: - providing at least one test object (9) to be conveyed; - operating the conveyor arrangement (1) in a installation mode of operation, thereby conveying said least one test objects (9) along the conveyor zones (2); - repeatedly transferring said at least one objects from an upstream conveyor zone (2e, 2f) to a downstream conveyor zone (2f, 2g); - wherein at least during said transfer, the upstream conveyor zone (2e, 2f) and the downstream conveyor zone (2f, 2g) are operated at different target speeds (Vt); - observing an operating value (IM) of said zone drive of said upstream conveyor zone and / or of said downstream conveyor zone, - from analyzing said observed operating value of said zone drives, determining a length dimensions (L, x5), namely a zone length (L) of one of said conveyor zones (2) and / or a position of a presence sensor (x5) within one of said conveyor zones (2).

Description

[0001] Method of determining a length dimension in a conveyor arrangement Description

[0002] The invention refers to a method determining a length dimension in a conveyor arrangement.

[0003] WO 2024 / 149872 A1 discloses a method for planning a conveyor arrangement comprising the following steps: using an IT planning tool by a user; by using the IT planning tool, arranging representations of a plurality of conveyor zones in a manner, so that an inlet of an downstream conveyor zone is linked to an outlet of an upstream conveyor zone; within the IT planning tool defining a plurality of destinations; performing an automated analysis of the arranged representations; based on the performed automated analysis, automatically generating a destination look up table, in particular a plurality of individual destination look up tables, indicating a list of conveyor zones and / or destinations, which are located downstream of each of the outlets of the respective junction zones.

[0004] EP 2 865 616 A1 discloses an apparatus for use with an object conveyor that conveys objects at an initial velocity; the apparatus comprising: means for determining a first velocity of said object, means for imparting a force to said object in a direction co-linear with said first velocity , so that said object exits said force impacting means at a second velocity; means for determining the second velocity of said object; means for determining a change in a parameter, said change being proportional to the force imparted to said object by said force imparting means.

[0005] The determined first velocity, second velocity and the change in said parameter is used for calculating the weight of said object. A similar device is disclosed in EP 2 865 616 A1 .

[0006] US 2003 / 196871 A1 discloses a conveying device which is adapted for correcting uneven spacing of successive articles. The device has two belt conveyors, wherein the conveying length of the belt is adjustable. During regular conveying operation a noser is movable forwards and backwards in response to detection of the at least one unevenly spaced article on the first conveyor belt.

[0007] US 2013 / 213768 A1 discloses an accumulation conveyor for conveying or stopping an object by controlling rotations of a plurality of rollers. These rollers form a conveying path. The conveying path is divided into a plurality of conveyor zones along its conveying direction. The length of each zone is determined appropriately in view of the maximum and minimum lengths of target articles to be conveyed and the like. Control means in each zone estimates a distance information concerning a distance between the article on an upstream zone and the article on the adjacent zone downstream thereof.

[0008] US 2020 / 024086 A1 , from a different technical area, discloses a material-conveying system comprising: a conveyor for conveying material to a bin and a conveyor positioning system associated with the conveyor. The conveyor positioning system comprises a processor for positioning the conveyor relative to the bin.

[0009] It is the object of the present invention to improve the installation of a conveyor arrangement and put such a conveyor arrangement into operation.

[0010] The invention comprises a method according to the main claim; embodiments are subject of the subclaims and the description.

[0011] The invention is in particular related to a conveyor arrangement which is adapted to convey an object from at least one feed-in station selectively to a selected destination from a plurality of destinations.

[0012] The basic conveyor arrangement comprises; a plurality of conveyor zones, each conveyor zone is adapted to convey an object from an inlet of said conveyor zone to an outlet of said conveyor zone; a plurality of controllers, adapted to control the operation of the conveyor zones; wherein said conveyor zones are arranged in a manner, that said object can be transferred from an outlet of an upstream conveyor zone to an inlet of a subsequent downstream conveyor zone. At least one of said conveyor zones is a junction zone having at least two outlets. A junction controller is adapted to control the junction zone in a manner so as to selectively convey said object through a selected outlet of the plurality of outlets of said junction zone.

[0013] The method comprising the following steps: providing a object to be conveyed; operating the conveyor arrangement in a installation mode of operation in particular outside of the normal mode of operation, thereby conveying said object along the conveyor zones; repeatedly transferring the object from an upstream conveyor zone to a downstream conveyor zone; wherein at least during said transfer, the upstream conveyor zone and the downstream conveyor zone are operated at different target speeds; observing an operating value of a zone drive of said upstream conveyor zone and / or of said downstream conveyor zone, from analyzing said observed operating value, determining a length dimension.

[0014] Due to the different target speeds, the object is at least temporarily driven by two drive means of different speeds. One effect is, that the object is subject to different and changing drive forces; another effect is that the drive means of the conveyor zones operated at different speeds are subject to suddenly changing load conditions, caused by the object having at least partially a speed which does not conform to the speed of the conveyor zone.

[0015] These suddenly changing load conditions are reflected in particular in peaks of an operating value of the drive, in particular the motor current. In another embodiment, the events can be determined by peaks in the rotational speed of a drive.

[0016] In an embodiment and in addition to observing said operating value the following steps are performed: observing a sensor signal of a presence sensors within one of said conveyor zones, from analyzing said observed operating value in combination with said sensor signal (S5), determining said length dimension.

[0017] In an embodiment said determined length dimension is a length of a conveyor zone and / or the determined length dimension defines a position of a presence sensor within the conveyor zone.

[0018] In particular the presence sensor is a light barrier. With the position of the light barrier in particular a location within the conveyor zone is meant, where an object is detected by the sensor.

[0019] In particular the length dimension defines a distance of said presence sensor from an inlet or an outlet of said conveyor zone.

[0020] In particular from analyzing said observed operating value of a zone drive of said upstream conveyor zone and / or of said downstream conveyor zone, an event is determined, when said object is transferring from said upstream conveyor zone to said downstream conveyor zone. Setting two or more of such events into relation, said length dimension can be determined.

[0021] An example embodiment of the invention is described in more detail with the help of the figures; herein show fig. 1 a conveyor zone in perspective view having a first embodiment light barrier; fig. 2 a basic conveyor arrangement; fig. 3. schematic representations of different conveyor zones; fig. 4 the layout of a conveyor arrangement; fig. 5 a table showing neighboring relations of the conveyor arrangement of figure 4; fig. 6 a selection of the conveyor zones of the conveyor arrangement of figure 4 during repeatedly transferring an object from an upstream to a downstream conveyor zone within an installation mode of operation.

[0022] Figure 1 shows an exemplary conveyor zone 2, comprising several conveyor rollers 3 which are driven together. For this purpose, one of the conveyor rollers 3 is designed as a motor- driven conveyor roller 3M, in particular motorized roller 3M. The motor-driven conveyor roller 3M is driven in particular by a three-phase motor arranged in the motor-driven conveyor roller 3M. Via one or more drive connectors 4, e.g. a drive belt, the conveyor rollers 3 of a conveyor zone 2 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 along a conveying direction d.

[0023] By means of a presence sensor 5, the presence of a conveyed object 9 arranged within the conveyor zone 2 can be determined. The presence sensor 5 thereby generates a sensor signal S5, which is connected via a signal line (not shown) to a local zone controller 11 presented further below. In the present embodiment the presence sensor 5 is a light barrier. The light barrier has a light source 5a, emitting a light beam 5b. The light beam 5b crosses the conveyor zone 2 and is reflected by a reflector 5c located on the opposite side of the light source 5a, back in direction of the light source 5a. Attached to the same housing of the light sources 5a there is included a light sensor 5d, receiving the reflected light beam 5b. In case the light beam 5b is received by the reflector 5c, no presence of an object 9 is detected. In case the light beam 5b is not received by the reflector 5c, a presence of an object is detected. The light beam 5b illustrates a sensor range of the presence sensor 5.

[0024] The conveyor rollers 3 and the presence sensor 5 are attached to a common support frame 6. The conveyor rollers 3 of several conveyor zones 2 can be attached to a common support frame 6.

[0025] The motor-driven conveyor rollers 3M are each controlled by at least one or a plurality of local zone controllers 11 . A single zone controller 11 can control the motor-driven conveyor rollers 3M of several conveyor zones 2. A plurality of local zone controllers 11 are arranged in a conveyor arrangement 1 (figure 2), which communicate with each other via a bus connection Figure 2 shows a basic conveyor arrangement 1 , where conveyor zones 2 as described previously are used. A plurality of zone controllers 11 control the operation of the conveyor zones 2. A PLC 14 (programmable logic control) may be provided to control the overall operation of the conveyor arrangement 1.

[0026] Scanners (not shown) may be arranged along the conveyor zones 2 and provide identification data relating to objects 9a..c passing the scanner in the conveyor zones 2. These identification data are sent via bus connection 13 to the PLC 14. The PLC 14 has access to an object data base (not shown), which provides destination data based on the identification of the objects 9. Based on the acquired data the PLC 14 provides operation instructions to a local zone controller 11 , how to handle the object 9, i.e. to which of the outlets O said object 9 is to be conveyed. For the proper operation it is not required that each conveyor zone 2 is equipped with an own scanner for identifying the object 9 located in each conveyor zone 2. As a consequence, some conveyor zones 2, usually on of the most upstream conveyor zones, are provided merely with a sensor for detecting merely the presence of an object 9, without identifying the object 9.

[0027] In an alternative embodiment as described in International patent application WO 2023 / 247237 A1 , no PLC or similar is required. Instead of a PLC the local zone controllers 11 are connected to a common higher-level object data broker, in particular via the bus connection 13, with which the zone controllers 2 are also connected to one another. The data broker provides destination data related to the identified objects and the zone controllers are adapted to control operation of the conveyor zones based on the provided destination data. For the purpose of the present invention the provision of a PLC is not required.

[0028] In particular the local zone controllers 11 control the motor-driven conveyor rollers 3M in such a way that the successively approaching conveyed objects 9 do not collide with each other, which is usually called “zero pressure accumulation”. The control takes place in such a way that essentially only one conveyed object 9 is present per conveyor zone 2. However, slight overlaps may occur. For example, an upstream conveyed object 9b located on an upstream conveyor zone 2c may already enter a downstream conveyor zone 2d even though the downstream conveyed object 9a has not yet left this downstream conveyor zone 2d completely. Among other things, the sensor signals S5 of the presence sensors 5 serve as input variables here, although it is ensured that the two conveyed objects 9 do not touch and thus do not damage each other.

[0029] In the following course of the invention, reference is made to conveyor zones 2, using a schematic representation of said conveyor zone 2 as shown in figure 3. Here figure 3a represents schematically a conveyor zone 2 of figure 1 , which has one first inlet 11 and one first outlet 01 . No more inlets I and outlets O are provided. The conveyor zone 2 can also be curved or from other shape.

[0030] Figure 3b shows the representation of another conveyor zone 2 having an extended scope of operation. Here in addition to the conveyor zone 2 of figure 3a the conveyor zone 2 has an additional, second outlet 02. The object 9 can be conveyed selectively from said first inlet 11 to one of said first and second outlets 01 , 02. Optionally, the conveyor zone 2 has an additional, third outlet 03. In this option, the object 9 can be conveyed selectively from said first inlet 11 to one of said first, second and third outlets 01 , 02, 03.

[0031] As an example, said conveyor zone 2 of figure 3b can be formed by a conveyor zone 2 as shown in figure 1 , which additionally is provided with a transfer device as described with reference to figure 5 of EP 3 222 564 B1 (in this document and figure the transfer device has reference sign 20).

[0032] Figure 3c shows the representation of a conveyor zone 2 having an extended scope of operation. Here in addition to the conveyor zone 2 of figure 3a, the conveyor zone 2 has an additional second inlet I2. Objects 9 can be conveyed from one of said first and second inlets 11 , I2 to said first outlet 01.

[0033] The transfer device as described with reference to figure 3b may also be suitable to provide said additional second inlet I2.

[0034] Figure 3d shows the representation of a conveyor zone 2 having an extended scope of operation. Here in addition to the conveyor zone 2 of figure 1 the conveyor zone has an additional second inlet I2 and an additional second outlet 02 and is an example as a combination of the embodiments of figures 3b and 3c.

[0035] All conveyor zones 2 are controlled by a local zone controller 11 as shown in figure 1 or 2, in particular wherein one local zone controller 11 may be adapted to control the operation of more than one conveyor zone 2.

[0036] Reference is made to figure 4. Here a conveyor arrangement 1 is shown, which comprises a plurality of conveyor zones 2 as shown in figure 3. For better individualization, the conveyor zones are provided with indices 2a0 - 2a7, 2e - 2q, 2r0 - 2r9, 2s0 - 2s9. Zone borderlines B are shown delimiting at least some of the conveyor zone.

[0037] The conveyor arrangement 1 comprises at least one feed-in station F1 , F2, where objects 9 can be put into the conveyor arrangement 1 . The feed-in station F1 , F2 may be attached to an exit of an upstream conveyor arrangement (not shown). Close to the feed-in stations F1 , F2 an identification scanner 7 is provided detecting an identification tag 97 (see also figure 1) of objects 9 to be conveyed during normal operation. The identification scanner 7 may be a barcode I QR-Code reader or an RFID reader, depending on the identification tag 97 attached to the objects.

[0038] The conveyor arrangement 1 comprises a plurality of destinations D1 - D16, to which an object 9 can selectively be conveyed.

[0039] Most conveyor zones are of the type shown in figure 2a, merely having one inlet and one outlet, e.g. conveyor zones 2a0 - 2a7, 2e - 2h, 2j - 2m, 20, 2, 2q.

[0040] Some conveyor zones 2 are junction zones of the type shown in figure 3b, having at least two different outlets, e.g. conveyor zones 2i, 2n, 2r1-2r3, 2r6- 2r8, 2s1 - 2s3, 2s6 - 2s8.

[0041] The conveyor zones 2 are controlled by a plurality of local zone controllers 11 a selection of which are shown in figure 4. Each of the zone controllers 11 are adapted to control at least one of the conveyor zones 2, which is exemplarily illustrated by lines for controller 11a.

[0042] The conveyor zones 2 are each equipped with a presences sensor 5 as shown in figure 1 .

[0043] It is to be differentiated between the identification sensors 7 and the presence sensors 5. Usually, a presence sensor 5 is much cheaper than an identification sensor and consequently the number of presence sensors 5 within a conveyor arrangement is significantly higher than the number of identification scanners 7 within said conveyor arrangement. During normal operation the signals S5 provided by the presences sensor 5 are not intended for identification of objects; instead the signals S5 merely provide a binary indication whether an object is present in the sensor range or not.

[0044] In particular a presence sensor is adapted to merely provide a binary signal indicating the presence and non-presence of an object in a defined sensor range without being adapted to provide identification data of an object.

[0045] The main task of a zone controller 11 is to arrange conveying operation of the conveyor zone 2, thereby initiating starting or stopping the drive motors of the conveyor zones 2 depending on the sensor signals 5a of the presence sensors 5. In case that the conveyor zone 2 is a junction zone, it is another task to initiate, that the object is taking the correct outlet of the plurality of outlets 01 , 02, 03.

[0046] Another task of the zone controller 11 is to control the conveying speed within one conveyor zone 2. As disclosed in detail in (yet not published) International patent applications PCT / EP2024 / 082669 and PCT / EP2024 / 086790 a variation of the conveying speed within the conveyor zones 2 can increase the conveying efficiency of the conveyor arrangement, thereby reducing stops and improving the overall throughput rate of objects 9. For the above improvements a deeper knowledge of the details of each conveyor zone 2 is required, in particular for the case, that some of the conveyor zone have different zone lengths.

[0047] As an example and according to the disclosure of WO 2024 / 149872 Aland WO 2023 / 247237 A1 it is required to know how the neighboring conveyor zones 2 relate to each other, i.e. which conveyor zone is upstream and downstream of a particular conveyor zone and which downstream conveyor zone can be reached via which of several exits.

[0048] In a previous configuration step, already the neighboring relations have been determined, e.g. via a method disclosed in (not yet published) PCT / EP2025 / 051938 or WO 2024 / 149872 A1 . The neighboring relations contain information i.e. which conveyor zone is upstream and downstream of a particular conveyor zone and which downstream conveyor zone can be reached via which of several outlets.

[0049] The table shown in figure 5 show the neighboring relations of the conveyor zones 2 in the conveyor arrangement 1 of figure 4. Each conveyor zone 2 is listed in a data set in the columns “zone ID”. For each listed conveyor zone the “upstream zones” and the “downstream zones” are indicated in the respective columns. In case that the listed conveyor zone is a junction zone, the data set comprises information, via which of the plurality of outlets 01 , 02, 03 the downstream conveyor zones 2 can be reached. A conveyor zone, which is not a junction zone, has merely one outlet. Also it may be indicate in the neighboring relations, that the conveyor zone has plurality of inlets 11 , I2.

[0050] In general, the method of determining the neighboring relation also includes the validation of a given neighboring relation, which was done previously e.g. with a method described in WO 2024 / 149872 A1 , at the manufactured conveyor arrangement.

[0051] Reference is now made to figure 6, showing a selection of conveyor zones of the conveyor arrangement of figure 4, here exemplarily the conveyor zones 2e, 2f, 2g, 2g are shown. During an installation mode a test object 9 is conveyed along the conveyor zones 2 in the conveying direction d.

[0052] The drives of the conveyor zones, in particular the motorized rollers 3M driving the conveyor zones, are operated in a manner so as to drive the rollers with a constant target speed Vt.

[0053] The target speeds Vt of each conveyor zone alternates from conveyor zone 2 to conveyor zone 2. So neighboring conveyor zones 2 are all driven at different target speeds Vt. Here merely as an example the conveyor zone 2e is driven at a target speed of 0,75 m / s, the next downstream conveyor zone 2f is driven at a target speed of 1 ,5 m / s, the next downstream conveyor zone 2g is driven at a target speed of 0,75 m / s, the next downstream conveyor zone 2f is driven at a target speed of 1 ,5 m / s.

[0054] The motor current IM of the of the conveyor drives of the individual conveyor zones 2 are shown below as well as the signal S5 of the presence sensor 5 of each conveyor zone 2, where the values for the individual conveyor zones are indicated with the suffixes e,f,g,h.

[0055] During the installation mode of operation the object 9 is conveyed in an upstream conveyor zone 2e at the target speed Vt of 0,75 m / s. When the object 9 is contacting the second conveyor zone 2f, which is operated at a higher target speed Vt of 1 ,5 m / s, said object 9 is suddenly accelerated by the second conveyor zone to achieve the target of Vt=1 ,5m / s within the second conveyor zone 2f.

[0056] This acceleration causes peaks in the motor current IM of the conveyor drives of the upstream conveyor zone 2e and the downstream conveyor zone 2f, as can be seen in figure 6 indicated at arrows E1 . Now the accelerated object also accelerates the drive means of the upstream conveyor zone 2e into a higher rotational speed leading to a reduction of the motor current IM in the drive of the slower upstream conveyor zone 2e, at the same time the accelerated object 9 leads to initially to an increase of the motor current IM of the drive means of the downstream conveyor zone 2f.

[0057] In another event during the installation mode of operation the object 9 is conveyed in an upstream conveyor zone 2f at the target speed Vt of 1 ,5 m / s. When the object 9 is contacting the downstream conveyor zone 2g, which is operated at a lower target speed Vt of 0,75 m / s, said object 9 is suddenly decelerated.

[0058] This deceleration causes peaks in the motor current IM of the conveyor drives of the upstream conveyor zone 2f and the downstream conveyor zone 2g, as can be seen in figure 6 indicated at arrow E2. Now the decelerated object 9 also decelerates the drive means of the upstream conveyor zone 2f into a lower rotational speed leading to an increase of the motor current IM in the drive of the faster upstream conveyor zone 2f, at the same time the decelerated object 9 leads initially to a decrease of the motor current IM of the drive means of the downstream conveyor zone 2g.

[0059] Such peaks indicate events E1 , E2, where the object 9 reaches the outlet of an upstream conveyor zone and an inlet of the next downstream conveyor zone, namely where the object 9 transfers from the upstream conveyor zone to the downstream conveyor zone. These timing if such individual peak events E1 , E2 can now be compared with the rotational speed R of the drives over time t of the conveyor drives between these events E1 , E2, multiplied by a known constant c, which takes into account any gear ratio and the diameter of a drive wheel or a conveyor roller. This results in the conveying distance that the object has traveled between these events E1 , E2. This distance is now set as the conveying length Lf of the respective conveyor zone 2f and can be included into the table of figure 5, see arrow P1.

[0060] Another value of importance is a position x5 of the presence sensor 5 within the conveyor zone (see also figure 1). Here the sensor position x5 conforms to the distance of the sensor range from the inlet I of the conveyor zone 2 in conveying direction d. Indicated at arrow E3 in figure 6 is an event for conveyor zone 2f, where the sensor signal S5 indicates that the object 9 enters the range of the presence sensor 5 in the conveyor zone 2f. This event E3 is set into relation with the previous event E1 where the object has entered the conveyor zone 2f. Herewith the position x5f of the presence sensor 5 in the conveyor zone 2f can be determined. In particular the position x5f represent the distance of said presence sensor 5 from an inlet or from an outlet of said conveyor zone. The respective value can be added in the table of figure 4 (see arrow P2 in figure 4).

[0061] The method as described above can be used to validate a length dimension which was obtained from another data source. As an example the zone length and / or the position of the sensor within a certain conveyor zone can be determined already during planning the conveyor arrangement with the help of the IT planning tool as shown in figure 4. Accordingly, the zone controller can be set up with the respective length dimension obtained from said IT planning tool as an example of another data source. Alternatively, another data source may be a manually edited list of length dimensions.

[0062] During the installation of the conveyor arrangement on site, the method according to the above description can be performed to obtain a length dimension of a conveyor zone by conveying the test object as described. If a comparison of the both length dimensions shows a significant difference, it can be assumed, that the value obtained from above method may not conform to the conveyor arrangement as originally planned (e.g. that the data is obtained from the IT planning tool). A service person can now be made aware of this fact by means of a corresponding message. List of reference signs

[0063] 1 conveyor arrangement 2 conveyor zone

[0064] 3 conveyor roller 3M motor-driven conveyor roller

[0065] 4 drive connector 5 presence sensor 5a light source 5b light beam 5c reflector 5d light sensor 6 support frame

[0066] 7 identification scanner (e.g. barcode reader) 9 test object 97 identification tag 11 local zone controller 12 local junction controller 13 bus connection 14 PLC

[0067] Vt target conveying speed B zone borderline C conveyor D destination E event F feed-in station I inlet IM motor current

[0068] O outlet d conveying direction S5 sensor signal (of presence sensor) L length of conveyor zone x5 Position of presence sensor within conveyor zone

[0069] 20:

Claims

Claims1. Method of determining a length dimension (L, x5) in a conveyor arrangement (1) during installation of the conveyor arrangement, the conveyor arrangement (1) comprising,- a plurality of conveyor zones (2), each conveyor zone is adapted to convey an object (9) from an inlet (I) of said conveyor zone (2) to an outlet (O) of said conveyor zone (2) and each conveyor zone have a constant zone length (L),- each conveyor zones has a zone drive (3M) adapted to provide drive power for conveying the object;- one or a plurality of controllers (11), adapted to control the operation of the respective zone drive (3M) of said conveyor zones (2);- in particular a plurality of presence sensor (5), each adapted to generate a sensor signal (S5, S9) indicating the presence of an object (9) within a conveyor zone (2), wherein said conveyor zones (2) are arranged in a manner, that said object (9) can be transferred from an outlet (O) of a, in particular direct, upstream conveyor zone (2) to an inlet (I) of a downstream conveyor zone (2); the method comprising the following steps:- providing at least one test object (9) to be conveyed;- operating the conveyor arrangement (1) in a installation mode of operation, thereby conveying said least one test objects (9) along the conveyor zones (2);- repeatedly transferring said at least one objects from an upstream conveyor zone (2e, 2f) to a downstream conveyor zone (2f, 2g);- wherein at least during said transfer, the upstream conveyor zone (2e, 2f) and the downstream conveyor zone (2f, 2g) are operated at different target speeds (Vt);- observing an operating value (IM) of said zone drive of said upstream conveyor zone and / or of said downstream conveyor zone,- from analyzing said observed operating value of said zone drives, determining a length dimensions (L, x5), namely a zone length (L) of one of said conveyor zones (2) and / or a position of a presence sensor (x5) within one of said conveyor zones (2).

2. Method according to the preceding claim, characterized inthat in addition to observing said operating value (IM): observing a sensor signal (S5) of a presence sensors (5) within one of said conveyor zones (2), from analyzing said observed operating value (IM) in combination with said sensor signal (S5), determining said length dimension (L, x5).

3. Method according to any of the preceding claims, characterized in that said determined length dimension (L) is a length of a conveyor zone (2).

4. Method according to any of the preceding claims, characterized in that said determined length dimension (x5) defines a position of a presence sensor (5) within the conveyor zone (2).

5. Method according to the preceding claim, characterized in that the presence sensor (5) is a light barrier.

6. Method according to claim 4 or 5, characterized in that length dimension (x5) defines a distance of said presence sensor (5) from an inlet (I) of said conveyor zone (2) or from an outlet (O) of said conveyor zone (2).

7. Method according to any of the preceding claims, characterized in that from analyzing said observed operating value (IM) of a zone drive of said upstream conveyor zone and / or of said downstream conveyor zone, an event is determined, when said object is transferring from said upstream conveyor zone (2e, 2f) to said downstream conveyor zone (2f, 2g) .

8. Method according to any of the preceding claims, characterized in that the upstream conveyor zone (2e, 2f) and the downstream conveyor zones (2f, 2g) are operated at different constant target speeds (Vt).

9. Method according to any of the preceding claims, characterized in that the observed operating value is a motor current (IM).

10. Method according to any of the preceding claims, characterized in that at least some of the conveyor zones (2) have different zone lengths (Lf, Lg).11 . Method according to any of the preceding claims, characterized in that within at least some of the conveyor zones (2) the presence sensors (5) are located at different positions (x5f, x5g) within the respective conveyor zone (2).

12. Use of the method according to any of the preceding claims for validating a length dimension obtained from another data source.

13. Use according to the preceding claim, characterized in that that length dimension value obtained from a second data source is compared with the determined length dimension value, and if the comparison reveals a difference, in particular above a threshold value, a message is provided to a service technician.

14. Use according to any of claims 12 or 13, characterized in that the another data source is an IT planning tool or a data list edited manually.

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