Patent Publication Number: US-2010131076-A1

Title: Control system, and method for configuring a control system

Description:
The invention relates to a control system with service-oriented architecture for a flexible production installation, comprising devices distributed in a decentralized manner, coupled to each other via a data communication system for the exchange of data and with at least one software component as well as electrical and/or mechanical components as well as to a process for the configuration of a control system by the development and implementation of service-oriented software components as components of a service-oriented architecture for devices distributed in a decentralized manner in flexible production installations. 
     There is a change in the future of automatization technology from central controls to small, intelligent electronic devices and components that are intended for use in flexible production systems. This technology requires a new engineering process. 
     The beginning of a service-oriented architecture has established itself very successfully from the area of ERP systems (Enterprise Resource Planning Systems) for linking together various services for the IT support of various business processes. An example is described in P. Lalanda; L. Bellissard; R. Balter: “Asynchronous mediation for integrating business and operational processes”; IEEE; January-February 2006; Internet Computing, volume: 10, issue: 1, pp. 56-64. This beginning was not known up to the present in control- and automatization technology. 
     Furthermore, an important trend in the designing of new products and the planning for their production installations is the universal, integral consideration of the product life cycle that is currently being advanced in many companies under the keyword of “digital factory”. In this connection the linking of the central types product, process and resource (PPR model) has become accepted as data model. 
     Product installations must, analogous to products, also be considered under the aspect of the life cycle since otherwise there can be no guarantee for the flexibility of the installation. 
     Fixed characteristic numbers of the system are no longer in focus here such as, e.g., a certain output, but rather the capacity of a production installation to adjust itself to different situations. This capacity is ensured by flexible components that can be reconfigured. 
     Different production installations for different production scenarios cannot be developed on real installations. The construction of appropriate installations for examining these production scenarios is too expensive. Therefore, a virtual development environment is necessary. This concerns a software program with which products, processes and resources of the production installation can be virtually reproduced. Product installations can be virtually tested with such a development environment. 
     Diverse research subjects (see below) examine the possibility of using service-oriented architecture for devices and components distributed in a decentralized manner in flexible production installations; however, a concrete solution for the development of service components and technologies based on Web service have not been able to be indicated. 
     Methods, technologies and tools for the modeling, design and implementation of networked systems are being designed in the framework of the European “Integrated Product SOCRADES” that are made available by intelligent, embedded devices. 
     The target of this project (SOCRADES) is the development of so-called “middleware” technologies, i.e., application-independent technologies that offer services for switching between applications. They should be based on a service-oriented architecture (SOA) and include line and wireless network technologies as well as have an open interface. Furthermore, such software components should contain apparatus-specific functionalities. 
     An engineering process for developing a service-oriented architecture for components distributed in a decentralized manner in flexible production systems as well as a structure of the software components as service-oriented module was not previously known. 
     Starting from the above, the present invention has the basic problem of further developing a control system and a process for the configuration of a control system in such a manner that it can be configured with low cost upon changes in the production installation or in different production scenarios. 
     The problem is solved by a control system in accordance with the invention in that the software component is derived from a process or partial process of a PPR model of the flexible production system, in which each software component comprises a control logic derived from the process or partial process, comprises a flexible interface for access to resources represented in the PPR model as well as comprises a communication interface for integration in the service-oriented architecture. 
     Furthermore, the problem is solved by a process in accordance with the invention in that the following process steps are carried out:
         Establishing of a PPR model of the flexible production system, taking into consideration product, process and resource information,   Breakdown of a production process contained in the PPR model into partial processes,   Development of the software components on the basis of the partial processes, in which each software component comprises a control logic derived from the partial process, a flexible interface for access to resources represented in the PPR model as well as comprises a communication interface for integration in the service-oriented architecture,   Development and analysis of different production scenarios as client-server architecture,   Implementation of the software components and of the associated client-service architecture into the control system.       

     The process steps are preferably carried out in a virtual development environment. 
     The control logic of a standardized software component is developed for a manufacturing process such as, e.g., a span sequence for fixing sheets to be welded. For installation planning a breakdown into partial processes has become accepted in practice, that is used as a guide for a control program. An engineering start based on components is therefore advantageously to be aligned according to the manufacturing process. This engineering process makes the functional elements available so that the service-oriented architecture can be used in the proper professional manner. 
     Various resources such as, e.g., actors, sensors, controls as well as electrical and/or mechanical components but also information and people are necessary for the processing of a process. The resources themselves are represented as virtual model in such a manner that their physical behavior can be reproduced in the most purposeful manner possible. In the development of the above-described software, also called services in the following, the reference to the resources is set by the PPR model. 
     The services as component of a combination of mechatronics, communication and intelligence are integrated into a total concept that assumes all control tasks. In the case of a service-oriented architecture they are preferably implemented as Web-service. 
     In a further process step, building on the standardized software components, a model of a life cycle for the production installation is developed. Care is to be taken here that a design is prepared not only for a specific target scenario but also that changing frame conditions are integrated into the planning setup. 
     Another process step is distinguished in that different production scenarios are presented and virtually analyzed as client-server architecture. The target here is that no re-programming of the production installation has to be carried out in practice if the frame conditions change. In contrast to the conventional procedure, different variants can be readily generated by a new client-server architecture in the service-oriented architecture used here. 
     Another preferred process step provides that the developed software components and the associated client-server architecture are implemented on different aggregation levels. 
     This brings it about that a continuous transition from a central control onto decentralized control components can be carried out. Here, the Web services can for their part invoke other Web services again. In a further step a library of generic Web services should preferably be generated. 
    
    
     
       Further details, features and advantages of the invention result not only from the claims, the features to be gathered from them, by themselves and/or in combination, but also from the following description of a preferred exemplary embodiment to be gathered from the drawings. 
         FIG. 1  shows a service-oriented architecture of a control system for a flexible production installation. 
         FIG. 2  shows a process graph of a virtual model of the production installation and Web services derived from it. 
         FIG. 3  shows an operating sequence diagram for establishing a model of a lifecycle for the production installation, and 
         FIG. 4  shows a schematic view of the client-service architecture for different aggregation levels. 
     
    
    
       FIG. 1  shows a schematic view of a control system  10  and service-oriented architecture for devices distributed in a decentralized manner such as control units  12 ,  14 ,  16  in the form of memory-programmable controls (SPS, mini-SPS) or intelligent modules as well as shows electrical and/or mechanical components  18 ,  20 ,  22  in the form of transport systems, motors or sensors of a production installation  24 . 
     The devices  12 ,  14 ,  16 , designated in  FIG. 1  as “devices”, can be arranged as memory-programmable control (SPS), mini-SPS distributed in production installation  24  or as intelligent control modules in the form of intelligent actors or sensors. The devices  12 ,  14 ,  16  are linked to each other via a data communication system  26  for the exchange of data, which data communication system  26  can be designed as a line bus system or as a wireless radio system. Furthermore, the devices  12 ,  14 ,  16  each have physical inputs and outputs  28 ,  30 ,  32  for controlling actors and for detecting sensor data. 
     One or more software components  34 - 44  is/are implemented in devices  12 ,  14 ,  16  via which different services such as, for example, diagnosis, data access or also control operating sequences are made available and invoked. 
     Thus, on the whole, each of the devices  12 ,  14 ,  16  forms a service as a combination of mechatronics, communication and intelligence that are integrated in a total concept that assumes all control tasks. 
     In the exemplary embodiment of the service-oriented architecture shown at least one software component is designed as a Web service. The service-oriented architecture makes possible a communication with equality of access between the devices  12 ,  14 ,  16  without a hierarchy concept being necessary. 
       FIG. 2  sketches the engineering process for flexible production installations on the basis of a service-oriented architecture. 
     Production installation  24  is represented by a PPR model containing product, process and resource information. The production process can be represented by a process graph  48  in which partial processes  50 ,  52 ,  54  are contained. Each partial process  50 ,  52 ,  54  also contains, in addition to logic information, that is, the sequence in time of actions, information about which resources are required for carrying out the particular partial process. The assumption of this information for the development of the services is a decisive design step. 
     The software components  34 ,  40 ,  42  described in  FIG. 2  of the devices numbered  12 ,  14 ,  16  in  FIG. 1 , that assume control operating sequences, are derived from one of the partial processes  50 ,  52 ,  54 . Each software component of a partial process contains a control logic  56  that is developed for a manufacturing process such as, for example, partial process  52  and is derived from process graph  48 . Since resources in the form of electrical and mechanical components  18 ,  20 ,  22  such as sensors, motors and transport systems are necessary for the processing of partial process  52 , a flexible interface  54  is implemented to which resource-specific data are assigned. Resources  18 ,  20 ,  22 , themselves are represented in the virtual engineering environment (PPR model) in such a manner that their physical behavior is reproduced in the most purposeful manner possible such as, for example, the time used for a movement process. 
     Finally, the standardized software components  34 ,  40 ,  42  are provided with communication interfaces  60 ,  62 . Communication interface  60  is implemented in the case of the service-oriented architecture as Web-based technology and makes possible the communication with other services and therewith an integration in a total concept. Resources  18 ,  20 ,  22  can be controlled and their states queried via interface  62 . 
     In this manner software components  34 ,  40 ,  42  are derived from all partial processes of the total process operating sequence that can then be implemented in the total system  10  of the service-oriented architecture. 
     In order to obtain a software component that is standardized as much as possible in which changing frame conditions of the production installation are taken into consideration, a model of a lifecycle for the production installation is developed building on the software components.  FIG. 3  shows a course in time of an installation life cycle. At first a definition of consumption of the production installation such as, for example, its transport capacity is performed. The planning of different variants for the flexible operation of the production installation takes place on this basis. The PPR model of the production installation accompanies the installation during its entire life cycle. The PPR model contains virtual images of devices and components of the production installation in which the software components are contained as module. 
     Based on such modules, the buildup of a virtual model then takes place with a flexible adaptation to different frame conditions in which the partial processes and therewith the control logic of the software components are constantly adapted. In order to raise the flexibility of the software components several variants of partial processes are implemented in the control logic, e.g., tensioning of a sheet with a differing tensioning configuration. 
     The advantage of the invention is characterized in the planning phase in that a production system can be represented virtually with “intelligent” models of devices and components, in which the “intelligence” of the modules used can be adapted for the flexible operation based on different frame conditions by planning different variants. Then, even a control program for the actual installation can be derived from such a PPR model taking into consideration the installation life cycle in changed frame conditions. 
     The invention offers the advantage on the hardware level that devices in the form of memory-programmable controls, robotic controls or the like can be flexibly adapted to changing product conditions without an expensive new programming being required. 
       FIG. 4  shows that different production scenarios can be represented in the form of a client-server architecture and virtually analyzed. For example, in production installation  24  a product  64  is transported on a pallet. The unit consisting of product and pallets is designated in the following as “client”. A service  66  such as “transport requirement” is requested via the data transfer medium  20 . The request is routed to device  12  as motor control of a transport structure, which for its part indicates a service request  68  to device  14  such as control of a conversion station. Finally, device  14  calls the general service  70  “transport system”, that that finally offers the requested transport capacity for the transport of the product. 
     The architecture shown in  FIG. 4  also shows that a continuous passage from a central control to decentralized control components  12 ,  14 ,  16  can be carried out. For their part, the Web services used can again call other Web services  72 . These requests can take place via a global network  74  like the Internet. Web services can be integrated in the IT landscape of a company. For example, a link to an MES  76  (Manufacturing Execution System) can be built up in order to query special routing information.