Robotics and ISA 88 Batch Control Standard - Opportunities and Challenges

Manufacturing processes can generally be classified as continuous, discrete or batch. An industrially well accepted way of structuring and controlling batch processes is presented in the ISA 88 standard (also known as IEC 61512). In exploring how this standard also could be used for discrete manufacturing processes, especially in robotic applications, different challenges and opportunities are found. The main opportunity is the advantage of having a stable and well tested and documented framework to be inspired by

Graphical Languages for Business Processes and Manufacturing Operations

The aim of this paper is to present trends, similarities and differences in the usage of graphical languages at the level of Process Control, manufacturing Operations and Business Systems. The paper also gives ideas of how a common language could be used to increase the integration between the three levels and what advantages this could bring to its user

Recipe-Based Batch Control Using High-Level Grafchart

High-Level Grafchart is a graphical programming language for control of sequential processes. Sequential control is important in all kinds of industries: discrete, continuous and batch. Sequential elements show up both on the local control level and on the supervisory control level. High-Level Grafchart combines the graphical syntax of Grafcet/SFC with high-level programming language constructs and ideas from High-Level Petri Nets. High-Level Grafchart can be used to control sequential processes both on the local level and on the supervisory control level. The main application area of High-Level Grafchart is control of batch processes, i.e., batch control. A batch process is a special class of sequential processes frequently occuring in chemical, pharmaceutical and food industries. Batch processes and batch control is currently the subject of large interest. A recent standard, called ISA S88.01, provides an important step towards a formal definition of batch systems. The specification of how to produce a batch is called a recipe. In the thesis it is shown how High-Level Grafchart can be used for recipe strucuring. By using the features of High-Level Grafchart in different ways, recipes can be represented in a number of alternative ways. They still, however, comply with the standard ISA S88.01. The different structures are presented and discussed. A simulation of a multi-purpose, network structured batch plant has served as a test platform. High-Level Grafchart, the recipe-execution system ad the batch plant are implemented in G2, an object-oriented programming environment

Polymorphism for State Machines

In production industry today a lot of engineering time is required to develop and maintain control applications. One part of the control applications are the state machines which typically are written in Grafcet/SFC. Several efforts have been made to extend Grafcet/SFC to achieve more effective and convenient development, e.g. by introducing hierarchical structuring, reusable sub-state machines, and various means for convenient exception handling. Working with these extensions available also result in more maintainable and overviewable applications. The extensions are included in the Grafchart language, developed at Lund University, and have proved to both work and scale well for real applications. Extensions to support object orientated state machines have also been proposed and evaluated with good results, e.g. for batch applications. To improve reusability and to facilitate abstract modeling, complete polymorphism similar to that of ordinary textual object oriented languages such as Java or C++ is proposed. As an example it is shown that this kind of modeling fits well for modeling, encapsulating, and using robot capabilities; it facilitates making a coordination sequence conveniently reusable for any robot with the required set of capabilities and it also makes the capabilities themselves reusable for other coordination sequences. The intention is to include polymorphism in future versions of the freely available Grafchart tool JGrafchart, enabling you to easily evaluate the advantages of polymorphic state machines for your specific domain

An Interactive PID Learning Module for Educational Purposes

The PID controller is the most common controller and it is taught in most introductory automatic control courses. To develop an intuitive understanding of the basic concepts of the PID controller and PID parameter tuning, interactive and freely available tools are important. A PID module for educational purposes has been implemented in JGrafchart, a freely available development environment for the graphical programming language Grafchart. JGrafchart includes interactive graphical elements such as live plots and it is possibile to create animated graphics, for example of a simulated process. JGrafchart's variables, for example controller parameters and modes, can be changed interactively while executing. The PID module will be included in future releases of JGrafchart with sample applications which can be used for example to demonstrate a PID controller live in lectures or to let students interactively change controller parameters and modes to develop an intuitive understanding of the PID controller and PID parameter tuning. The sample applications are designed for users without any knowledge about JGrafchart and can be used to control both simulated and physical processes

High-Level Grafcet and Batch Control

The application of Grafcet to supervisory control applications with special emphasis on batch control is described. Grafchart, a Grafcet based G2 toolbox is presented. An industrial application where it is currently used on-line is described. High-Level Grafcahrt is an extension of Grafchart that is based on High-Level Petri nets and Object-Oriented Programming. It increases the parameterisation and structuring possibilities of Grafchart. The SP88 draft batch control standard is shown to be well suited for representation by High-Level Grafchart

Teaching Manufacturing Operations and Strategies in Higher Education

Students at higher technical educations e.g., bachelors and masters, are traditionally taught in software programming and factory automation. Students at higher economical and management schools are exposed to different strategies and their economical impacts. However, in many education programs, the larger perspective, of how to combine the technical and the economical aspects is not highlighted. Technology Management is a unique program at Lund University Sweden, where a selected number of students from the school of economics and management and from the engineering faculty are taught together during their last year of study. Their views on problems and challenges in todays industry often complement each other. The course Technology, Strategies and Structures includes e.g. projects done in collaboration with industries. This paper includes a discussion about how knowledge about Manufacturing Operations and Strategies, can be incorporated in higher technical and economical studies, and it describes some industry projects done by students

Object-Tokens in High-Level Grafchart

The paper presents an high-level extension to Grafchart, a Grafcet-based toolbox for supervisory control applications. The extension allows tokens to be objects with attributes. Contrary to most high-level extensions to Petri Nets and Gracet it is not based on inscriptions