Patent ID: 12204316

DETAILED DESCRIPTION

FIG.1shows a rough schematic view of a production plant10according to the disclosure. The mechanical components of the corresponding transport system30are known, although in some cases they may be modified in minor ways for the disclosure. Purely by way of example, reference is made to https://www.boschrexroth.com/de/de/produkte/produktgruppen/montagetechnik/transfers ysteme/transfersystem-ts-1 and https://www.boschrexroth.com/de/de/produkte/produktgruppen/montagetechnik/transfers ysteme/transfersystem-ts-2plus, where the Rexroth TS1 and T2plus transport systems with all their components are described. The exemplary production plant10shown in a rough schematic view inFIG.1can be constructed both according to the TS1 system and the T2plus system.

Firstly, the transport system10in this case comprises a total of six transport sections31, each of which is designed as a straight double-belt conveyor. They therefore have two parallel, continuously rotating conveyor belts or conveyor chains, each of which is set in motion by a common transport drive32, namely an electric motor. The conveyor belts always run in the same direction, usually at a constant speed. It is of course possible to adapt the transport speed and the transport direction to the requirements of the production process. The workpieces11to be processed are transported on the transport sections31. These are typically carried on a plate-like, usually square, workpiece carrier, which in turn rests directly on the above-mentioned conveyor belts, so that it is carried along by friction.

The individual transport sections31are immediately adjacent to each other at diverter devices40, at curves41or at junctions33. They usually pass through the processing stations20without interruption. The same applies to the straight-through path of a diverter device40. The diverter devices40can be lift transverse units (see e.g. DE 10 2018 204 644 A1), but other constructions (see e.g. DE44 39107 C2) are also known. Common to all the diverter devices40is that two transport sections31abut each other in a T-shape, wherein the path taken by the workpiece11is switchable. Curves41are known, for example, from DE44 31836 B4 or DE 195 00 546 B4. In a curve41, two transport sections31, which differ in their direction, usually by 90° or 180°, are adjacent to each other. A curve41is usually designed in such a way that the workpiece11is driven along the entire curve path.

A further element of the transport system30according to the disclosure is formed by the stop gates42, which can be used to stop the workpieces11despite the continuation of the transport section31. For this purpose, a stop for the workpieces11is usually raised above the conveying plane defined by the conveyor belts. If the stop is lowered below the transport plane, the workpiece11can continue to move along the conveyor section31. Such a stop gate42is known from EP 2 072 429 B1. The processing stations20are typically equipped with two stop gates42. A first stop gate is used to accumulate several workpieces11as a working stock. A second stop gate holds a single workpiece11in the processing position, where it can also be precisely aligned by means of a positioning device (not shown). For example, the diverter devices40are provided with a stop gate on an inlet side, so that it can be ensured that only a single workpiece11passes through the diverter device40at a time.

It is also important to point out the reading devices43which are located at different points of the transport system30. The workpieces11, in particular the workpiece carriers, are equipped with information carriers, which in most cases are RFID tags that can be read out wirelessly, wherein optically readable barcodes or QR codes can also be used. A reading device43can read the information carrier when the workpiece11is located in a narrowly confined reading range of the reading device43. In the simplest case, a unique serial number of the workpiece11or the workpiece carrier is read. RFID tags can also store information that is sent or written by one reading device43and read out by another reading device43. In addition to the above-mentioned reading devices43with a narrowly confined reading range, additional reading devices (not shown) may be available with a larger reading range which can cover the entire production plant10.

The transport sections31are linked to a branching system of transport routes by means of the diverter devices40and the curves41. For example, a workpiece11entering from the top left inFIG.1can be transported to all three processing stations21;22;23. From there it can be transported onward to the exit at the top right inFIG.1. A transport route is also provided via which all the processing stations20can be bypassed.

The transport system30according to the disclosure comprises a plurality of computers50. They can be at least capable of running a Linux operating system or a comparable operating system. In order to save costs, it is preferable to use computers50that are less powerful, such as microcontrollers. In the simplest case, each processing station20and each diverter device40is spatially associated with a computer50, so that the cable paths73to the connected stop gates42, reading devices43and transport drives32are short. Via these cable paths73a data exchange73can take place between the relevant computer50and the above-mentioned components42;43;32. The computer50can therefore control the directly connected components42;43;32or read data from them.

In addition, the various computers51-57are connected for data exchange via a computer network (no.71inFIG.2). The computers50are configured in such a way that each computer50can enter into a data exchange connection with the components42;43;32connected to another computer.

Computer networks used for control purposes are known from the prior art, such as PROFINET (https://de.wikipedia.org/wiki/Profinet) or Sercos (https://www.sercos.de/). These are characterized by a real-time data exchange capability. Within the scope of the present disclosure, the use of such complex systems for the data exchange on the computer network is deliberately avoided. Rather, it is intended that simple messages in a binary format will be exchanged asynchronously over the computer network. Real-time control is preferably carried out solely via the direct cable paths73to the computers50. This can significantly minimize the transmission bandwidth occupied on the computer network71. The initial decision according to the disclosure can be used, among other things, to implement the control of the entire plant in real time, i.e. with specified maximum response times.

FIG.2shows a diagram of the computer network connections71between the computers51-57. For example, the computers51-52in the processing stations (No.20inFIG.1) can each be connected to a shared network switch74, so that they can send Ethernet or WiFi messages among themselves directly without the need for IP routing. For example, the computers54-57in the processing stations (No.40inFIG.1) can each be connected to a shared network switch74, so that they can send Ethernet or WiFi messages among themselves directly without the need for IP routing.

The two exemplary network switches74are connected to a network router75which uses IP routing to enable data exchange between the two subnets defined by the network switches74. A consequence of this network structure is that, for example, a data exchange between the computers51and53has a lower latency than a data exchange between the computers51and56. In the first case, only the upper subnet inFIG.2is required for the data exchange, while the lower subnet and the network router are not used for the data exchange. In the second case, the entire computer network is occupied for the data exchange. This precise fact can be taken into account in taking the initial decision according to the disclosure, by this decision being taken in such a way that none of the computer network connections71shown inFIG.2is overloaded. It goes without saying that the network switches74and the network routers75are an integral component of these computer network connections71, so that their overloading is also important.

It is conceivable that the above-mentioned network switches74and the above-mentioned network routers75are integrated into an associated computer50. It is conceivable that all computers50are connected exclusively by means of point-to-point connections.

FIG.3shows a diagram of the data exchange connections72between the reading devices43, the stop gates42, the transport drives32, the diverter devices40and the control processes70;70a;70b;70c;70d. According to the disclosure, a plurality of control processes70should be available. For example, it may be intended to execute a control process70for each workpiece (no.11inFIG.1). This control process would therefore have to take the second decision and decide which processing station should be approached next. InFIG.1, for example, the processing station51and52are of the same type. The first control process70afor the workpiece11ainFIG.1would therefore have to decide which of the two processing stations51and52inFIG.1it will approach next. As a result, the stop gates42and the transport drives32would have to be controlled accordingly. In order to take this second decision, the first control process70arequires information that is as comprehensive as possible about the state of the production plant, which is provided by a digital twin76implemented by a fourth control process70d.

The fourth control process70dsubsequently exchanges data with almost every component of the production plant. As a result, in terms of the utilization of the computer network it is largely immaterial on which computer50the fourth control process70dis running. In order to minimize the utilization of the computer network, at least when querying data from the digital twin, it is preferable to provide a copy of the digital twin on many computers, or even on all computers, which at least comprises the immediate environment of the respective computer. The various (partial) copies are implemented by other control processes, which are not shown inFIG.3. The digital twin76is preferably implemented using “conflict free replicated data types” (https://en.wikipedia.org/wiki/Conflict-free_replicated_data_type), so that the various copies are reliably consistent over time.

When implementing the above-mentioned second decision, the first control process70ausually only adjusts the stop gates42and transport drives32that are arranged in its immediate vicinity. Considering the first workpiece11ainFIG.1, the lowest loading on the computer network would result if the first control process70awere to be executed on the first computer51inFIG.1. This is precisely the subject of the initial decision according to the disclosure, for example. When the first workpiece moves through the production plant as processing progresses, the initial decision is made again multiple times with the result that the first control process70ais executed on another computer. For example, the software package MOSIX (http://www.mosix.cs.huji.ac.il/pub/MOSIX_wp.pdf) can be used to transfer a control process from one computer to another. It is also possible to run the various control processes using containers (see e.g. https://de.wikipedia.org/wiki/LXC), since such containers can be transferred from one computer to another very easily.

The programming language Erlang (https://www.erlang.org/) is preferred when using less powerful computers, wherein its virtual machine is used in particular. A corresponding software architecture is known from the website https://www.grisp.org/.

REFERENCE SIGNS

10production plant11workpiece11afirst workpiece11bsecond workpiece11cthird workpiece20processing station21first processing station22second processing station23third processing station30transport system31transport section32transport drive33junction between two adjacent transport sections40diverter device41curve42stop gate43reading device50computer51first computer52second computer53third computer54fourth computer55fifth computer56sixth computer57seventh computer70control process70afirst control process70bsecond control process70cthird control process70dfourth control process71computer network connection72data exchange73cable path for data exchange, bypassing the computer network74network switch75network router76digital twin