Project-Oriented Internet-Based Learning in the Field of Control Engineering Rainer Bartz University of Applied Sciences, Cologne, Germany in cooperation with S.Engell , Chr. Schmid2, H.Roth3, N.Becker4, H.M. Schaedel5 1 University of Dortmund / 2 Ruhr-Universität Bochum 3 University of Siegen / 4 University of Applied Sciences Bonn-Rhein-Sieg 5 University of Applied Sciences Cologne 1
Abstract: While control engineering is taught since decades in nearly all engineering programs, most control engineering courses classically divide the overall task into small subtasks. These subtasks can be prepared and solved independently and thus avoid to put too much complexity into each single step. Though this is smart and in many cases necessary as well, there is always the immanent risk of not considering the overall dependencies and thus missing the final goal. A group of universities funded by the German State of Northrhine-Westfalia has been established, with the goal to use advanced Internet and multimedia technologies to support projectoriented learning. In such an environment students have to solve real-world control engineering problems. Depending on a guidance level, they will not only have to solve individual subtasks but also will have to decide on the selection and sequence of those subtasks in order to reach the goal of the projects. State-of-the-art technology like MATLAB, LabView, VRML tools, web cameras, and others will be applied to provide an optimum information transfer to the student and support to prepare, conduct, and analyze the individual experiments, which range from simulation to real physical process models. Motivation In many of today’s modern systems, control engineering is one of the major engineering disciplines. It is required to implement a smooth system behavior or even to provide the required functionality at all. Control engineering has made its way from electronics and mechanics to a variety of engineering fields and is found in chemical processes, civil engineering, traffic management, and many others, including non-engineering fields like business processes. Teaching control engineering has therefore become inherent part of many course programs, and improvements in the available teaching methods and tools will have a broad impact. Though methods and tools have reached a quite high level of quality and functionality during the past decades, there are always opportunities for advancements. Proceedings of the 2002 ASEE/SEFI/TUB Colloquium Copyright © 2002, American Society for Engineering Education
One of today’s drawbacks in most control engineering education programs is the missing overview. A lot of mathematical methods are usually required to cover the theoretical background of this widely self-contained matter, each of them needed at a different stage in an overall control engineering project. These methods are usually trained independently. How to combine them to finally solve a control engineering project is often omitted due to lack of time or lack of applicable real-world examples (sometimes, though, the only thing missing is a didactical concept). This drawback is where LEARN2CONTROL can be brought in; it will support both, educators and students, to look at the whole of a control project. It will provide not only a collection of real-world projects but also a platform for an evolving rich set of additional teaching modules and examples. Goals The overall goal of LEARN2CONTROL is to enable “project-oriented learning” and to support it by using modern technology (based on PCs and Internet). Though the main focus of LEARN2CONTROL lies in the field of control engineering (where the need for project-oriented education had been identified first), the methods and tools developed can be applied to other disciplines as well. There are several issues that need to be considered to reach this goal. 1) The view for the whole of a project must not get lost at any time. Though a project will require a set of individual subtasks, it always must be evident how they are related to the project. This can be achieved by an appropriate user interface, where the student can navigate between those subtasks and still be aware of their context. 2) Students should be guided according to their level of education. While the first project usually will require a higher level of guidance, learning should result in increased experience and thus both, solving a subtask as well as deciding on an appropriate sequence of subtasks, can be more and more imposed on the student. 3) A representative number of projects should be available. Control engineering can be applied to very different real-world problems. Most of the methods however are based on mathematical procedures. Therefore it is always necessary to translate the real-world problem into a mathematical description and to translate the mathematical solutions back into corresponding real-world parameters. Those translation steps are problem specific and are trained best when a variety of different problems is presented. 4) It should be possible to easily enhance LEARN2CONTROL. Not only adding new control projects but also extending the application focus (addressing fields other than control education) should be possible. This shall be achieved by providing a ‘project education framework’ and not just a single monolithic education solution. The development of LEARN2CONTROL is not yet finished, but what is currently available will be described in this article and already shows that the identified issues have been successfully addressed.
Proceedings of the 2002 ASEE/SEFI/TUB Colloquium Copyright © 2002, American Society for Engineering Education
Main Portal and User Navigation From a user’s (i.e. student’s) point of view LEARN2CONTROL presents itself as an Internet application. Figure 1 gives an overview of its components. Table 1 lists the software components that must be available on the user’s PC. The user will access LEARN2CONTROL through the main portal using an Internet browser. The main portal allows logging in/out, viewing the available projects (learning units), and selecting them.
project descriptors, data, learning units on the partner sites
main portal to Learn2Control
project servers
Learn2Control server
accessing remote experiments on the partner sites experiment servers
INTERNET
user client Web browser user interface
project data
navigation
Since working with experiments that involve real-world systems is only useful for a single user at a time, the main portal provides facilities to book an experiment for a specific time interval. Additionally, the main portal will provide forum and chat facilities for exchanging information and getting support.
workbench
state machine
MATLAB SIMULINK calculation and simulation engine
Learn2Control Toolbox
When a user has selected a project, and is authorized to access it, he will be forwarded to the server of that project. While the main portal is located at UniFigure 1: System architecture of Learn2Control versity of Siegen, the projects are hosted on project servers at the provider universities. Most of the projects will deal with real-world systems. Interfacing those systems with LEARN2CONTROL is up to the provider and typically uses separate experiment servers, which also reside at the provider’s location. Table 1: Required client software
Windows NT 4.0, Win98, Win2000, Windows XP Netscape Navigator 4.7x MATLAB Student License V5.3 or higher CosmoPlayer or Cortona Player Learn2Control specific MATLAB toolbox
When starting with the selected project, the browser on the user PC will present a user interface with two major components: a navigation and a workbench component. Proceedings of the 2002 ASEE/SEFI/TUB Colloquium Copyright © 2002, American Society for Engineering Education
1. The navigation component The navigation component is based on a virtual reality 3D model and uses VRML players for displaying and navigating within the VRML world. Figure 2 shows an example navigation window of a project from Cologne. Each project is represented by a VRML world. The essential elements are the subtasks that contribute to the project. They are represented as nodes (spheres), and a color coding tells whether a subtask has already been finished, is in process, still needs to be processed, or cannot yet be processed. Nodes may be organized hierarchically. Clicking on a node either allows to start processing a subtask or displays the next level of hierarchy (resp. its VRML room). Arrows between nodes tell about dependencies, and additional navigation-type nodes allow to navigate between VRML rooms.
Figure 2: Example of a navigation component of Learn2Control
The navigation component can always be brought on to the top and allows the user in each phase of his project to see the current subtask in the context of the whole project. The navigation component can hide the dependencies of subtasks as well as the state of a subtask, depending on the current guidance level of a user. Thus experienced users may have to select an appropriate sequence of subtasks by their own and take care about the project progress without being supported by the system; they may even be faced with subtasks (nodes) that are not useful for that project at all. 2. The workbench component The workbench component is the main project user interface. Each subtask will be explained here, and the student will use the controls available to submit his decisions and his results. An example of a workbench layout is given in Figure 3. The workbench typically will make use of a set of tools for specific purposes: MATLAB (which is required at least as a student version) is used by the workbench to save intermediate and project results and eventually restore them later. Though the user does not need to know how to use MATLAB (it just must be installed and will be used transparently by the workbench), if he knows, he may also use MATLAB for own calculations, diagrams, etc.. Proceedings of the 2002 ASEE/SEFI/TUB Colloquium Copyright © 2002, American Society for Engineering Education
Figure 3: Example of a workbench component of Learn2Control
TaskMachine, a state machine Java-applet, which takes care of the states and state transitions between the individual subtasks and thus links the VRML world with the workbench activities. L2CToolset, which combines a set of powerful tools for displaying signal graphs, formulas, and system block diagrams. The workbench will provide access to a glossary and presents the theoretical background to solve the given tasks. Finally, the workbench will allow accessing the remote experiments. The experiments may differ significantly in complexity and required background knowledge. They are subject-specific and the design of interaction with a real-world system or a remote system simulation depends on the experiment. The experiments currently under development are described later in this article. An experiment implementation may also apply the workbench tools (e.g. it may make use of the capabilities of MATLAB and exchange data with the workbench). The main portal and the available projects can be accessed through the LEARN2CONTROL homepage 1.
Proceedings of the 2002 ASEE/SEFI/TUB Colloquium Copyright © 2002, American Society for Engineering Education
Development Environment and Tools A project provider will have to generate the contents of the navigation and workbench components and the logic behind its project, and will also have to implement means to access his experiment. LEARN2CONTROL supports the project implementation phase by providing several tools and stubs. Table 2 lists the software components, which are required to develop a LEARN2CONTROL project (in addition to those shown in Table 1). Table 2: Required additional softwarefor a project provider
DOME Version 5.3 any professional HTML editor any professional Web Server eventually software required to access the experiment
Figure 4 shows the LEARN2CONTROL architecture as seen from a view of a project provider. 1. Steps to define the navigation component The definition of the project, its execution logic, its subtasks, their interdependencies (including possible alternative paths, and the determination of project completion), the positioning of the VRML nodes, etc. is performed using DOME 2. user interface DOME comes with a graphical user internavigation stub face and thus allows the provider to define subtasks and their dependencies graphically. With the built-in simulation facility the provider may test the execution logic before proceeding to the next workbench step.
DOME
code generator
HTML-Editor
Within the LEARN2CONTROL project a code generator has been developed, which can be embedded into DOME. JavaScript library After defining the project in DOME the state machine stub project author invokes this code generator and creates two sets of project descriptions: a VRML file, used by the VRML Figure 4: Authoring a project player. a Java source file describing the execution logic used by TaskMachine to keep track of the state of the subtasks. These files will automatically be integrated and compiled to fit and run within their stubs. The only thing a provider must perform is copy the output of the code generator to appropriate locations within the Internet directory trees. From then on, the VRML player will present the VRML world and allow navigation, and TaskMachine is ready to accept commands (through JavaScript methods) for handling subtask states. Proceedings of the 2002 ASEE/SEFI/TUB Colloquium Copyright © 2002, American Society for Engineering Education
2. Steps to define the workbench component The workbench component typically consists of a set of HTML pages. HTML statements as well as JavaScript functions and method calls are used to implement them. A powerful HTML editor should be available to efficiently create these pages. Besides the huge amount of free material to design Web pages, LEARN2CONTROL provides several useful tools for specific purposes; some of them have been developed within the predecessor project DYNAMIT 3: The TaskMachine applet provides methods to get information about available subtasks and flags, to set the state of a subtask (e.g. to specify that the subtask is finished), to find out whether the conditions to enter a subtask are already met, etc.. A MATLAB plugin allows to execute MATLAB commands on the client PC or from the Internet. A Graphics plugin allows to show emf-type graphic files that are generated by MATLAB or reside on the client PC or on the Internet. The HotEqn applet provides an easy means to display even extensive formulas without the need to first convert them to pixel graphics. The HotSystemEd applet allows a user to interactively generate a SIMULINK-like block diagram within a browser. 3. Granting access to an experiment Experiments can either be based on simulation data (virtual system) or on real-world systems. If only a simulation shall be included, the provider just needs to create HTML pages that allow accessing the simulation data and eventually modifying the input of the simulated system (in order to get a variety of data from his simulation). If the provider intends to set up a real-world system as a LEARN2CONTROL experiment, he needs to implement browser access to that system to allow a user to observe the signals and eventually modify the system’s inputs. He may additionally allow observing the system via WebCams and downloading sampled signals to the client PC for further evaluation. There are many possible ways to implement such access; more information on the Cologne solution can be found later in this paper. Current Projects under Development LEARN2CONTROL started in 2001 and includes 5 German universities as project partners: Ruhr-Universität Bochum University of Dortmund University of Siegen University of Applied Sciences Bonn-Rhein-Sieg University of Applied Sciences Cologne Each of the partners will contribute a project: Bochum: control of a hydraulic unit (real-world system) Dortmund: control of a chemical heating process (virtual system) Siegen: control of a mobile robot (real-world system) Bonn-Rhein-Sieg: control of a chemical process (virtual system) Cologne: control of a Twin-Rotor system (real-world system) Proceedings of the 2002 ASEE/SEFI/TUB Colloquium Copyright © 2002, American Society for Engineering Education
An example for a real-world experiment is the TwinRotor System of the University of Applied Sciences Cologne. The system is shown in Figure 5. Its major part is the Twin-Rotor itself with propellers, sensors, and some driver and conditioning electronics in its base. It is controlled and observed through a multipurpose I/O board plugged into a PC (the experiment server). Figure 6 shows an example of the system’s Web-based user interface (with input controls for setpoint, PIDparameters,...) and a resulting signal (vertical angle).
Figure 5: Twin-Rotor system
Figure 6: Example of the Twin-Rotor user interface (Cologne)
LabView is used as control and measurement software. It is programmed in National Instruments G language (producing so-called VIs, ‘virtual instruments’) and allows a very flexible management of the system. Proceedings of the 2002 ASEE/SEFI/TUB Colloquium Copyright © 2002, American Society for Engineering Education
A separate administration PC hosts a database, which manages the booking calendar of the Twin-Rotor system. A user may book the experiment over Internet. As soon as he tries to connect to the experiment server to perform measurements, the responsible LabView VI will check with the booking database (through SQL commands) whether that user is currently permitted to interact with the system. Some LabView VIs present HTML pages with input controls to the user, to allow setting parameters (like desired rotor speed) of the system. Others collect data (e.g. angular position) from the system and show them to the user within HTML pages and as column-based data files for download to the user’s PC. The system is complemented with WebCam facilities; they allow to observe the system in real time (however, they require to install some additional software on the client PC). Conclusions LEARN2CONTROL – though not yet completed – provides a very versatile platform to offer project-oriented Internet based education modules. Within LEARN2CONTROL not only the framework but also several specific projects are under development and will be used in the courses of the partner universities. This allows an immediate feedback from using the framework to adapting it and eases optimization. An online evaluation facility with associated database allows public or anonymous rating of the projects and thus contributes to their quality. LEARN2CONTROL includes a VRML based navigation through the overall project while working on specific subtasks; it always allows the user to keep an eye on the whole. User-specific guidance levels can address different skill-levels. LEARN2CONTROL makes available a powerful development platform to introduce projectoriented learning at other universities, with additional real-world projects, and even focussing on new disciplines.
Acknowledgement: This project is funded by the MSWF (the ministry responsible for education, science, and research within the State of Northrhine-Westfalia, Germany) through the UVM (a university multimedia initiative), Project No. 01050203. References: 1. LEARN2CONTROL homepage: www.learn2control.de 2. DOME: DOmain Modeling Environment; free tool under GNU GPL; www.htc.honeywell.com/dome/ 3. DYNAMIT: dynamit.esr.ruhr-uni-bochum.de 4. LEARN2CONTROL e-mail contact:
[email protected] 5. The author’s e-mail:
[email protected] RAINER BARTZ, Prof. Dr.-Ing. Professor Bartz has worked in the field of automotive electronics and testing facilities for more than a decade. He has been appointed to a professorship for control engineering in 1997 and since then has offered courses in control engineering, fieldbus systems, signals and systems. His interests include controller design, system identification and simulation, software design, international study programs, eLearning, and Internet technologies. Proceedings of the 2002 ASEE/SEFI/TUB Colloquium Copyright © 2002, American Society for Engineering Education
