Control device

Abstract

Control device (2) for monitoring and / or controlling the inventory of a plurality of components in a production facility, in particular a series production facility, with a plurality of sensors (4, 6) for monitoring the inventory of a plurality of components, with at least one central unit (8) which is in data transmission communication with the sensors (4, 6) and determines reorder times for the individual components depending on the output signals of the sensors (4, 6) and preferably sends corresponding reorder signals, wherein the sensors (4, 6) are in radio communication with at least one conversion and converter unit (10) which converts the signals sent by the sensors (4, 6) for forwarding to the central unit (8), wherein, for establishing a data transmission connection with the conversion and converter unit (10), at least some of the sensors (4, 6) are each assigned a low-power radio module with a maximum transmission power of ≤ 15 mW.

Description

The invention relates to a control device for monitoring and / or controlling the inventory of a plurality of components in a production, in particular a series production.For example, in the series production of automobiles, it is necessary for a smooth production process to keep the required components available at different points in the production process. In this case, a plurality of similar components can be accommodated in a material container in each case, wherein a plurality of such material containers is arranged one behind the other in a feed channel. The feed channel can be formed, for example, by an inclined roller track. During the manufacturing process, the components are first removed from a material container that is at the front in the outlet direction. When this material container is completely emptied, it can be removed from the feed channel, so that material containers arranged behind it slide.In order to keep a sufficient number of components ready, it is necessary to use a filled material container for each empty material container removed from the outlet path. For this purpose, a worker who has removed the last component from a material container and optionally removed the material container from the feed channel can manually request a filled material container by means of a device provided for this purpose. Upon request for a material container, the latter is transported to the rack and inserted into the feed channel at the rear end in the discharge direction. A device used for this purpose is known, for example, from WO 2004 / 073 329 A2.In order to simplify the control of the inventory of the required components, it is known from DE 20 2007 012 926 U1 to automate the requirement of required components, so that a manual retrieval by a worker is no longer required. For this purpose, DE 2007 012 926 U1 discloses a sensor module of the relevant type for use in a system for monitoring and / or controlling the inventory of a plurality of components in a production, in particular a series production, which has a sensor for monitoring an inventory of a component and a radio module for establishing a data transmission connection to a receiving unit. The sensor is used to sense whether, for example, a sufficient number of material containers is still present in a feed channel for feeding a specific component.If it is determined by means of the sensor that there is no longer a sufficient quantity of material containers in the feed channel, a signal is sent by means of the radio module to a receiving unit, which can be part of a central unit of a system for monitoring and / or controlling the inventory of a plurality of components, for example. The central unit can then control the refeeding or re-ordering of the required components. For data transmission to the receiving unit by radio, a WLAN (wireless local area network) is used here, as is known per se from WO 2004 / 073 329 A2. The use of a WLAN is based on the idea that a WLAN infrastructure is already present in many companies.EP 1 521 198 A2 discloses a control device for monitoring and / or controlling the inventory of a plurality of products having a plurality of sensors for monitoring inventory of a plurality of products, having at least one central unit which is in data transmission connection with the sensors, and determining re-placement times as a function of output signals of the sensors and sending signals thereto. The sensors are in radio communication with at least one conversion and conversion unit for forwarding to the central unit.DE 10 2007 031 174 B4 discloses an arrangement with storage containers, wherein position information relating to the object in the storage container is transmitted by means of cableless transmission means.The object of the invention is to provide a control device for monitoring and / or controlling the inventory of a plurality of components in a production, in particular a series production, the performance of which is improved and the flexibility of which is increased, in particular with regard to the incorporation of additional sensors.This object is achieved by the invention specified in claim 1.The invention is based on a control device for monitoring and / or controlling the inventory of a plurality of components in a production process, which control device has a plurality of sensors for monitoring inventory of a plurality of components. The sensors serve to monitor, with respect to a component or a component type, whether a sufficient inventory quantity of the relevant component or the relevant component type is still present. If a specific component or a specific component type is supplied, for example, via material containers, a supply channel designed as an inclined roller track can be used, in which a plurality of material containers, which each contain the same component or the component type, are arranged one behind the other. A corresponding sensor is then used to sense whether a material container is still located in the feed channel.The control device further comprises a central control unit which is in data transmission connection with the sensors and which, depending on output signals of the sensors, determines re-placement times for the individual components and preferably sends corresponding re-placement signals.The invention provides that the sensors are in radio communication with at least one conversion and conversion unit which converts signals transmitted by the sensors for forwarding to the central unit. The conversion and conversion unit, which is also referred to below for short as a conversion unit, is thus in data transmission connection on the one hand with the sensors and on the other hand with the central unit.Because the sensors communicate according to the invention with the central control unit via the converter unit, it is possible to combine different network infrastructures with a view to optimizing the performance and the resources used. For example and in particular, the converter unit can communicate with the central control unit via a LAN or WLAN connection, while the communication between the sensors and the converter unit can take place outside a LAN or WLAN network. A low-power radio module with a maximum transmission power of <=15 mW is assigned to the sensors, wherein the sensors preferably communicate with the converter unit via a transmission protocol optimized with regard to a reduced transmission duration.In this way, both the power consumption of the individual sensors and the transmission duration required for transmitting sensor state information ("inventory quantity sufficient: no material requirement required" or "inventory quantity insufficient: material requirement required") can be reduced, so that as a result, a significantly reduced power demand for electrical power results compared to an infrastructure in which the sensors communicate with the central control unit via a WLAN, for example. If the sensors are battery-operated, the batteries have a considerably extended service life because of the reduced power requirement. This saves considerable costs both in terms of material costs for the batteries and equipment costs for the replacement of the batteries and, moreover, reduces the environment because the amount of empty batteries which have to be disposed of as a special waste is substantially reduced.Moreover, the intermediate connection of a converter unit offers additional freedoms with regard to an expansion of the control device. Starting from an infrastructure in which the sensors communicate with the central control unit via a WLAN connection, for example, sensors can be added due to the converter unit which no longer communicate directly with the central control unit but via the converter unit. In this way, the possibility is created of retrofitting an existing infrastructure in steps with regard to the use of low-power radio modules, for example. As a result, an existing system can be replaced gradually by a system that is more power-efficient and energy-efficient.The control device according to the invention thus has increased flexibility with regard to the structure, retrofitting and re-upgrading of a system for monitoring and / or controlling the inventory of a plurality of components in a production process.In order to use an already existing network infrastructure, an advantageous further development of the invention provides that the conversion and conversion unit is in data transmission connection with the central unit via a LAN and WLAN connection. The transmission of data from the converter unit to the central unit is thus carried out in a LAN or WLAN network. This has the advantage that encrypted transmission is carried out at this interface, at which sensitive data are transmitted in relation to one another. The relatively high power consumption resulting here due to a very high power requirement of a WLAN network, for example, is no longer important because only one radio connection is required for connecting a converter unit to the central unit, the energy requirement of which can be supplied from the power network in any case. In contrast, the radio connections between the sensors and the converter unit, which can be present in large numbers corresponding to a large number of individual components, can be operated according to a more energy-efficient method.In order to reduce the energy requirement, in particular in the case of battery-operated sensors or sensor modules, and thus to further extend the battery life, an advantageous development of the invention provides that, in order to establish a data transmission connection to the conversion and conversion unit, at least some of the sensors are each assigned a low-power radio module having a maximum transmission power of <=15 mW. In this way, compared to a WLAN infrastructure in which transmission is carried out, for example, at a maximum transmission power of 100 mW, a significantly reduced energy requirement results with a correspondingly extended battery life. This leads to a considerable reduction in costs, on the one hand with regard to the material costs of the batteries and, on the other hand, with regard to the setup costs incurred in connection with an exchange of the batteries.At the central unit, the readjustment of components can be organized in different ways. It is thus possible, for example, for the readjustment of components to be carried out manually by an operator on the basis of data which are derived from the sensor status information of the individual sensors and are available at the central unit.Semi-automatic re-ordering is also possible in such a way that when a fixed quantity inventory for a component is undershot, a warning signal is triggered at the central unit and an operator then carries out a re-ordering process.According to the invention, however, (fully) automatic re-ordering is also possible in such a way that the central unit automatically calculates re-ordering times on the basis of the sensor status information for the individual components and automatically sends re-ordering signals. In this way, a high efficiency is achieved, wherein the control device can be linked, for example, to a bearing logistics of a bearing in which the individual components are stored. It is also possible according to the invention that a readjustment signal is transmitted to an external supplier. The generation of the readjustment times can be effected, for example, in such a way that components are supplied "just in time".With regard to automatic re-ordering of components, an advantageous further development of the invention provides that the central unit sends re-ordering signals as a short message to at least one mobile telephone. The readjustment signals of the individual components can be integrated here, for example, on a smartphone into software for material ordering and demand planning.Another advantageous further development of the invention provides that the central unit sends re-ordering signals via e-mail. Both in the case of a transmission of readjustment signals as a short message and in the case of a transmission by e-mail, the advantage results that the respective readjustment signal can be transmitted in parallel to different recipients. A combination of different transmission paths is also possible.The sensors of the control device according to the invention can operate according to any suitable operating principle. In this respect, an advantageous further development of the invention provides that at least one sensor is an electromechanical sensor. Such electromechanical sensors are available as relatively simple and cost-effective and robust standard components and can be used in particular where it is necessary to monitor, for example, whether a material container is still located in a feed channel.Another refinement of the invention provides that at least one sensor is an optical sensor. Corresponding optical sensors are also available as relatively simple and cost-effective and robust standard components.A development of the aforementioned embodiment provides that at least one optical sensor is designed as a light scanner. In this embodiment, the sensor provides a yes / no signal (for example: "material container is present" or "material container is not present") corresponding to an electromechanical sensor.Another advantageous development of the embodiment with the optical sensor provides that at least one optical sensor has a camera. The use of a camera offers the advantage, for example, that information exceeding a yes / no signal can be transmitted to the converter unit and from there to the central unit. For example, it is possible to evaluate, on the basis of a still or moving image of a production section, by means of methods of image processing and pattern recognition, how large the inventory quantity of a component is.In order to further improve the energy efficiency and performance, another refinement of the invention provides that at least one sensor is designed for unencrypted data communication with the conversion and conversion unit. This embodiment is based on the idea that sensor status information, which frequently consists essentially of a serial number or another code for identifying the sensor and a yes / no signal, is not sensitive data and accordingly an encryption is not required. On the other hand, by omitting an encryption at the interface between the sensors and the converter unit, a further reduction in the transmission duration and thus a further improvement in the energy efficiency is achieved.Another advantageous development of the invention provides that at least one sensor is designed for bidirectional data communication with the conversion and conversion unit. In this embodiment, the transducer unit can acknowledge, for example, a sensor status information transmitted by a sensor with an acknowledgment signal.According to the invention, it is basically sufficient if an individual sensor is assigned to at least one component inventory for detecting the inventory quantity of the component, as provided by a practical development of the invention. In this embodiment, a single sensor is assigned to a component or a component type, so that a yes / no signal ("stock quantity sufficient" or "stock quantity insufficient") can be transmitted to the converter unit.An advantageous further development of the invention provides that at least two sensors are assigned to at least one component inventory for detecting the inventory quantity. In this embodiment, it is possible on the one hand to operate with redundant sensors at particularly sensitive points of the manufacturing process, i.e. to provide two parallel-operating sensors for detecting the inventory quantity of a component.On the other hand, according to another advantageous embodiment, there is the possibility that for spatially resolved detection of the inventory quantity of a component inventory, in particular along a feed channel for the relevant component, at least two sensors are arranged spaced apart from one another. In this embodiment, a sensor chain can be arranged, for example, along a feed channel, so that detailed information can be derived about how many material containers are still located in the feed channel. In this way, the possibilities of demand planning are extended, so that as a result the process safety of the manufacturing process can be further increased. This embodiment has independent of the feature of claim 1, according to which the sensors are in radio connection with at least one conversion and conversion unit which converts signals transmitted by the sensors for forwarding to the central unit, but in combination with the remaining features of claim 1 has independent inventive significance.According to the invention, it is sufficient if the control device has a single conversion and conversion unit. According to the invention, however, it is also possible to provide a plurality of conversion and conversion units which are each in data transmission connection on the one hand with a plurality of sensors and on the other hand with the central unit. In this case, it is possible, for example, to provide a plurality of transducer units spaced apart from one another in space and to assign different sensors to the individual transducer units in accordance with their respective spatial arrangement. Such a constellation is particularly favorable when the individual sensors have low-power radio modules with a correspondingly short range. The use of a plurality of converter units thus enables decentralization of the network infrastructure of the control device according to the invention.It is also possible according to the invention to use, parallel to one another, on the one hand sensors which are connected to the central unit via a converter unit and, on the other hand, sensors which are connected directly to the central unit. In a corresponding embodiment, on the one hand, the advantages of an existing network infrastructure and, on the other hand, the advantages of a more energy-efficient network infrastructure based on low-power radio modules are to be combined with one another.The at least one conversion and conversion unit can be designed according to the respective requirements. In particular, the or each conversion and conversion unit can have a media converter or media converter.A method according to the invention for monitoring and / or controlling the inventory of a plurality of components in a production, in particular a series production, is specified in claim 15. The method according to the invention is characterized in that a control device according to one of claims 1 to 14 is used.The invention is explained in more detail below with reference to an exemplary embodiment with reference to the attached drawing. All features described, which are represented in the drawing and claimed in the patent claims, form the subject matter of the invention on their own and in any suitable combination with one another, independently of their summary in the patent claims and their reference back and independently of their description or representation in the drawing.It shows: FIG. 1 is a block diagram of an embodiment of a control device according to the invention, FIG. 2A schematically and by way of example an operating state in a feed channel in a series production and FIG. 2B is a view similar to FIG. 2A showing the feed channel in another operating state.FIG. 1 shows an exemplary embodiment of a control device 2 according to the invention for monitoring and / or controlling the inventory of a plurality of components in a production, in particular a series production. Mass production can be, for example and in particular, mass production of automobiles. However, it is also possible according to the invention to use the control device according to the invention in other areas of series production or also single production.The control device has a plurality of sensors for monitoring inventory of a plurality of components, wherein two sensors are shown merely by way of example in FIG. 1 and are provided with the reference numerals 2, 4. According to the respective requirements, the sensors 2, 4 can be provided in any suitable number and configuration. Thus, electromechanical, optical or other active principle sensors can be provided, for example. An exemplary embodiment of an electromechanical sensor, with which the presence of a material container in a feed channel is detected, is specified in DE 20 2007 012 926 U1. The content of DE 20 2007 012 926 U1 is hereby incorporated by reference in its entirety into the present application. The sensors 4, 6 are preferably battery-operated sensors which are thus independent of an electrical grid and which can be arranged at any suitable point in the manufacturing process for monitoring the inventory quantity of a respective component.The control device 2 further comprises a central unit 8, which is in data transmission connection with the sensors 4, 6 and determines adjustment times for the individual components depending on output signals of the sensors and preferably sends corresponding adjustment signals.According to the invention, the sensors 4, 6 are in radio communication with at least one conversion and conversion unit 10, which is in data transmission communication with the central unit 8 and converts signals transmitted by the sensors 4, 6 for forwarding to the central unit 8.In the exemplary embodiment shown, the conversion and conversion unit, which is also referred to below for short as a conversion unit, is in data transmission connection with the central unit 8 via a WLAN connection, so that an already existing WLAN infrastructure can be used in this respect.In the exemplary embodiment shown, a low-power radio module with a maximum transmission power of <=15 mW is assigned to each of the sensors 4, 6 for establishing a data transmission connection with the converter unit 10. In the exemplary embodiment shown, the radio modules assigned to the sensors 4, 6 are designed for unencrypted, bidirectional data communication with the converter unit 10. For data transmission of a sensor state information (for example: "inventory quantity sufficient: no re-ordering required" or "inventory quantity insufficient: re-ordering required"), a proprietary transmission protocol is used in the illustrated exemplary embodiment and the sensor state information is transmitted in a data packet that has a length of <=20 bytes. Furthermore, the radio modules assigned to the sensors 4, 6 are designed for transmitting / receiving operation in an open frequency band. In Germany or Europe, this open frequency band can be, for example, in the range of 868 MHz, while for the USA it can be, for example, 915 MHz. In the illustrated embodiment, a radio system of 868.025 MHz and a bandwidth of 150 KHz is used.In addition to the sensors 4, 6, manual retrieval devices can also be provided, via which a worker can retrieve material, for example by confirming a retrieval button. FIG. 1 shows, by way of example, such a retrieval device 12 which is in data transmission connection with the central unit 8.In addition to the sensors 4, 6, which communicate with the central unit 8 via the converter unit 10, there may also be further sensors in a system which contains the control device according to the invention, which are directly in data transmission connection with the central unit 8. In FIG. 1, such a sensor 14 is shown merely for the sake of example. The constellation shown in FIG. 1 represents, for example, a situation in which conventional radio connections in which a sensor 14 is directly in data transmission connection with the central unit 8 via a WLAN are replaced step by step by radio connections in which low-power radio modules are used and in which these sensors 4, 6 communicate with the central unit 8 via the converter unit 10.Merely for the sake of example for any desired number of transducer units according to the respective requirements, a further transducer unit 10' is shown in FIG. 1, which is in data transmission connection with sensors 4', 6'.Thus, signals are combined at the central unit 8 via the transducer units 10, 10', which signals represent the sensor status information of a plurality of sensors. On the basis of these signals, demand planning can be carried out at the central unit with regard to the individual components whose inventory quantity is sensed by the sensors and a re-ordering can be triggered. The central unit 8 can transmit corresponding data, for example, to a control station 16, at which corresponding measures for re-ordering components can then be initiated manually, semi-automatically or fully automatically. The central unit can also transmit readjustment signals, for example, by a short message to at least one mobile telephone 18, as shown in FIG. 1. In addition, the central unit 8 can also transmit readjustment signals by e-mail to a decentralised computer 20, as likewise illustrated in FIG. 1. The control device 2 according to the invention enables a flexible integration of existing WLAN infrastructure with an energy-optimized radio network infrastructure and thus offers a high level of flexibility with regard to the design and dismantling of an energy-efficient radio network infrastructure.If the components required for the manufacturing process are stored or at least temporarily stored during the operation in which the manufacturing process is carried out, the control device 2 according to the invention can be incorporated into the storage logistics of the operation. In such a constellation, readjustment signals are transmitted to the internal-operation bearing logistics, which remove the respectively required components from an internal-operation bearing and introduce them into the production process at the respectively required point.The control device according to the invention can, however, also be used advantageously when components required for the production process are stored or temporarily stored in non-internal terms during the operation in which the production process is carried out. In such a constellation, signals representing the component inventory of a component can be transmitted from the central unit 8 or a converter unit 10, 10' to an external computer, for example a supplier. On the basis of the signals transmitted in this way, the inventory quantity for components can then be determined externally to the operation, for example at a supplier, and as a function thereof a re-delivery of required components to the operation in which the production process takes place can be initiated. In this way, an internal storage or intermediate storage of components in the operation in which the manufacturing process is carried out is superfluous, because the supply of components can take place just in time. A further advantage of such an embodiment is that the supplier or another external site allows precise inventory quantity determination with respect to the respective components at any time.In particular in the latter constellation, it is advantageous if a relatively accurate statement about how many components of a component type are still available can be derived on the basis of the signals supplied by the sensors 4, 6. In this sense, it is advantageous to analyze a component inventory in more detail, in particular in a spatially resolved manner. In the following, we will explain with reference to an exemplary embodiment how this is possible, for example, within the scope of a control device 2 according to the invention.According to the invention, it is basically sufficient if an individual sensor is assigned to a component inventory for detecting the inventory quantity of the component. In order to increase the process safety, however, at least two sensors can be assigned to at least one component inventory for detecting the respectively current inventory quantity.FIG. 2A shows an operating state in a feed channel in which a plurality of material containers are arranged one behind the other and run on a roller conveyor 28. The material containers 22, 24, 26 each contain the same components. A worker working at the corresponding location first removes the components from the material container 22 at the front in the direction of discharge. When this material container is empty, it is removed from the roller conveyor 28 so that the material containers 24, 26 slide on. A plurality of sensors 30, 30', 30'' spaced apart from one another in the discharge direction are arranged along the discharge path, which sensors are designed in this exemplary embodiment as electromechanical sensors, as are known in principle from DE 20 2007 012 926 U1. The sensors can thus be used to sense the locations along the feed channel at which one of the material containers 22, 24, 26 is located.FIG. 2A shows a constellation in which the sensor status information of the sensors 30, 30' indicates that a material container 24 or 26 is located in the area assigned to them, while the sensor status information of the sensors 30", 30"' indicates that a material container is no longer located in the area assigned to them. It can thus be established at the central unit that there are still sufficient components available.FIG. 2B shows a constellation in which it can be determined on the basis of the sensor state information of the sensors 30, 30', 30" and 30"' that there is no longer a material container in this region. From this it can be deduced that the corresponding components are tilted so that a re-ordering can be triggered. On account of the spatially resolved detection of the inventory quantity achieved as a result, more precise information about the respectively current inventory quantity can be derived at the central unit 8, with the result that the demand planning and re-ordering is made even more precise.FIG. 2 illustrates a spatially resolved detection of the inventory set along a line. However, it is also possible according to the invention to arrange a plurality of sensors in a two-dimensional and grid-like manner, so that a detection of the inventory quantity with a two-dimensional resolution is made possible therewith. Instead of signals supplying a yes / no signal as sensor status information, according to the invention, other sensors can also be used, for example cameras as optical sensors.

Claims

Control device (2) for monitoring and / or controlling the inventory of a plurality of components in a production, in particular a series production, having a plurality of sensors (4, 6) for monitoring inventory of a plurality of components, having at least one central unit (8) which is in data transmission connection with the sensors (4, 6) and, as a function of output signals of the sensors (4, 6), establishes readjustment times for the individual components and preferably transmits corresponding readjustment signals, wherein the sensors (4, 6) are in radio connection with at least one conversion and conversion unit (10) which converts signals transmitted by the sensors (4, 6) for forwarding to the central unit (8), wherein, in order to establish a data transmission connection with the conversion and conversion unit (10), at least some of the sensors (4, 4, No. 6) is assigned a low-power radio module with a maximum transmission power of ≤15 mW.Device according to Claim 1, characterized in that the conversion and conversion unit (10) is in data transmission connection with the central unit (8) via a LAN and / or WLAN connection.Device according to one of the preceding claims, characterized in that the central unit (8) sends readjustment signals as a short message to at least one mobile telephone (18).Device according to one of the preceding claims, characterized in that the central unit (8) sends readjustment signals by e-mail.Device according to one of the preceding claims, characterized in that at least one sensor (4, 6) is an electromechanical sensor.Device according to one of the preceding claims, characterized in that at least one sensor (4, 6) is an optical sensor.Device according to claim 6, characterised in that at least one optical sensor is designed as a light scanner.Device according to claim 6 or 7, characterised in that at least one optical sensor has a camera.Device according to one of the preceding claims, characterized in that at least one sensor (4, 6) is designed for unencrypted data communication with the conversion and conversion unit (10).Device according to one of the preceding claims, characterized in that at least one sensor (4, 6) is designed for bidirectional data communication with the conversion and conversion unit (10).Device according to one of the preceding claims, characterized in that an individual sensor (4, 6) is assigned to at least one component inventory for detecting the respectively current inventory quantity of the component.Device according to one of the preceding claims, characterized in that at least two sensors (30, 30', 30", 30"') are assigned to at least one component inventory for detecting the respectively current inventory quantity.Device according to claim 12, characterised in that for spatially resolved detection of the inventory quantity of a component inventory, in particular along a feed duct for the relevant component, at least two sensors (30, 30', 30", 30"') are arranged spaced apart from one another.Method for monitoring and / or controlling the inventory of a plurality of components in a production, in particular a series production, characterized in that at least one control device according to one of Claims 1 to 13 is used.

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