Enhancing Control Engineering Education

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Enhancing Control Engineering Education using a

CACSD Didactic Environment

Eduardo Rocha Loures

[email protected]

Marcos da Silveira

Marco Antonio BusettiYasemin Arda

{dasilveira, busetti}@ccet.pucpr.br

Graduate Program in Production Systems EngineeringPontifical Catholic University of ParanRua. Imaculada Conceio, No. 1155.

80.215-901 - Curitiba - Brazil

Abstract - The classical approaches to teach of

control systems present drawbacks, such as: (i)

they provide by step knowledge acquisition, the

general overview of the problem being sometimes

underemphasized; (ii) academic examples aremainly used, dealing with simple concepts and

problems; (iii) laboratory experiments are either

simple or under developed. Design aspects of

control systems when applied to practical process

are important to improve the knowledge of the

students and to motivate the utilization of modern

methodologies as an emergent technology for

application in industry. In this work, we point out

some important aspects for conceiving a new

educational product. We describe our experiences

in creating a didactic environment for teaching

and learning of control theories in Engineering

courses based on CACSD (Computer Aided

Control System Design) and its extension to theresearch field around industrial problems. Two

distinct proposals arise from these experiences for

reducing the gap between the theoretical and

practical classes, and for teaching the control

systems development cycle using mathematical

tools and real plants under the virtual

instrumentation concept

Keywords: control engineering education ,learning environment, CACSD, virtualinstrumentation.

1. Introduction

We can find on the literature some approachesfor specific areas that demonstrate acceptableresults, but until now no education tool (on theauthors knowledge) is attest as a good support forall kind of education process. However, we canfind some consensual topics about knowledgeacquisitions [2], [4], [7], [8].

Knowledge cannot be reduced to a text orjust words.

Students do not receive knowledgepassively; they are building their know-how in an active way.

Errors are symptoms of students wrongconceptions.

The learn process is dynamic.

In general, there are many divergences aboutthe methodology that should be applied ineducational systems. In our opinion, the educationprocess should be based on the students difficultiesand take into account the teacher abilities to usedifferent resources during the classes. Inadequatemethodologies can make the students believe thatEducation is a mechanical procedure, i.e. if theyfollow specific rules they will always obtain the

same results. An alternative way to avoid thissituation is the application of heuristicsenvironment instead of algorithms one. In theheuristic environment, experimental learning andindependent discovery are encouraged, divers tools,

as well as simulations systems, modeling, games,programming languages, intelligent tutors andspecialist systems, etc. are offered to assist thestudents. In the algorithm environment, thelearning results from knowledge transmission asclassical tutors, demonstrations and exercises [9].

Numerous researches demonstrate that thelearning happens through the association of new

structures with other already existent ones. Thus,better results can be obtained if the organizations oflessons take into account this point and associatenew information with previous knowledge.Another aspect that must be considered is a studentlearns by increase, combine and rearrangecognitive maps, it can lead us to suppose thattheoretical information is better understood whenassociated with practical information.


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On the other hand, the abusive use ofcomputers presents some disadvantages [15].Experiences have pointed that: Students tend todiscover the problem solutions by empiricalmethods, it can affect the real problem perception;The use of software resources implies in theknowledge of the available tools, it can propitiate a

student dependence on these tools; Universities areusing some commercial software (for instance,MatLab, Mathematics, LabView, Intouch, ), theylead to considerable advances in control systemscourses, but in spite of that, they are not designedto be an educational tool.

We can summarize that the use of computersin control practical classes presents threeadvantages and one risk: Low cost of theexperiments; The teacher has more time tosupervise the pedagogical applied methodologyinstead of solve complex equations on theblackboard; The natural attraction for computers(by young people) can be used to stimulate studentsduring the class; There is also a great risk illustrateby the sentence: "Buy a computer, it will think foryou ".

These observations motivate the LAS/PUCPRteam to develop some tools and methods tointegrate Control theory and practical classes as apart of a project that started in 1997 with thedevelopment of ACONSYS (Authorship ControlSystem) tool [13]. The main objective of thisproject is to analyse some problems in ControlEngineering Education [12], [14] and proposesolutions that can help professors to elaboratecourses based on computer. That tool is composedof two modules: (1) the creation module that is auser-friendly interface to introduce the Controltheory and the presentation sequence as well as theelaboration of the exercises. (2) the presentationmodule that displays the theory of Control and theproposed exercises.

The second project named VIEnCoD (VirtualInstrumentation Environment for ControllerDesign) [6] is an integrated environment based onCACSD and is aimed to study and design generalcontrollers. Here, the main goal is offering adidactic environment to facilitate the contributionof the students and researchers to create, modifyand/or to supervise every level (identification,design, optimization and implementation) of theControl System Development Cycle (CSDC). Theutilization of the CSDC methodology in Educationprocess can give more options to teach differentcontrol strategies, thus by studying each level ofCSDC the students can develop a global vision ofsystem functioning.

This paper is organized as follows. TheAconsys project is described in section 2. Insection 3 the VIEnCoD projet is also described.Finally, the integration of these tools is proposed inthe last section presenting also perspectives andconclusions.

2. The ACONSYS projectThe motivation to start this project was the

reduction of the gap between Control theoryeducation and practical context. We look for amethodology that offers different educationalstrategies to the students build their ones know-how and induce them to develop their skills bysurpassing the lesson scope , searching informationin others sources, or by testing new situations. Aheuristic methodological approach associate withcomputer tools to support classes on practicalenvironments was adopted. The main topicsconsidered during the development of this projectare:

The system must offer a friendly interfacebased on multimedia resources to exposethe class subject.

Real experiments and/or simulations mustbe possible by these tools. The studentshould have an active role on the learningprocess.

The students must be able to create or tomodify the experiments parameters; it canmotivate them to develop their on

sensitivity about the subject.The information must be available to thestudents at anytime and in anyplace.

The purposes of the system are not basedon artificial intelligent with cognitive rules

to acquire knowledge, to detect the studentprofile and to propose solutions. At thisphase, we limit this tool to be a support for

the teachers during the classes and for thestudents (for example, to review thesubject) at anytime.

The ACONSYS prototype has two differentenvironments: one to elaborate courses and theother to present it. The first one is used by theteacher to introduce the subject of the class, toorganize it into a didactic way, establish the defaultparameters of experiments as well as the links tothe others software that can be used to assist theclass.

An example of this environment is presentedin Figure 1. The second one is used by the student


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to follow the class, as showed in Figure 2. In thisenvironment all information elaborate by theteacher can be accessed. The students can introduce

their ones opinions about each page (assured by theitem student note and protect it by a password) andmark this page as important one (a direct link isprovide for the five most important pages).

Figure 1. Author environment

Figure 2 . Presentation environment

Another role of this environment is theacquisition of students performance data,information like time spent in each topic, markobtained solving the exercises, list of visited pages,etc. can be used by the teacher to diagnose thelearning difficulties of one student in particular orof all the class. It can be an important informationsource to improve the learning process.

A greater ACONSYS structure detailing isshown in Figure 3. In this representation are threedistinctive environments with functional support

features for the author, the course, the simulation orthe user. They are:

Author environment, where courses areassembled. In this environment it ispossible to structure a class containing anexplanatory theoretical text with links tofigures, videos, audio and exercises. It isalso possible to communicate with the

simulation environment, integrating praxis

with theoretical contents;

Presentation environment, responsible forthe interface with user. Within thepresentation environment the student isable to access a class that has been

elaborated in the conception environment,read the explanatory theoretical text withall its limits, resolve exercises and alsoperform praxis simulation associated tothe class;

Simulation environment, where processesare simulated and result presented. Thesimulation environment was designed asan object integrated to other twoenvironments. Through the conceptionenvironment it is possible to configure,create or test a specific simulation. Withthe presentation environment it is possible

to execute the simulation proposed by theauthor and change part of it, if necessary.

The integration among environments is onlypossible through the file system, with exception ofthe simulating environment that can interact withthe other two environments through configurationcommands originated at the conceptionenvironment, and execution environment,originated at the presentation environment. A morecomplete description of the this global structure ofACONSYS is found in [13].

s

3. Author environment

Text EditionTools

LinksTools

2. Simulation environment

1. Presentation environment

User

Multimedia

exercises

hipertext

Exercises

Imagerelationship

Single option

another tools

Multiple optionsquestions

statement

answers

extern

comments

List of pages modifications List of links

Imagem

Sound Video

explanation

Text

Parts Models Resource

Local

anotherapplication

MatLab, Mathematica,etc.

images

title

number

at

aba

se

Sy

st

e

Figure 3 . Global structure of ACONSYS

3. The VIEnCoD project

The VIEnCoD (Virtual Instrumentation-basedIntegrated Environment for Controllers Design)

conception was motivated by the need of an


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environment that fulfilled the development andresearch purposes, parallel to academic objectivesregarding study, analysis and project of classic andcomplex control strategies for the various plants,from mechatronic systems. Hence, the gap betweencontrol theory, its real application context and theresearch performed by the professor or industry

professional could be eliminated. The theory-research-application concept is acknowledged byenhancing the university-industry technologytransfer and improving control engineeringknowledge transfer quality through exchangedexperience [5]. This context is illustrated in Figure4.

Laboratory - instrumentation, control, automation

SSupport

education

Industry

User

Library

Models

Software

Experiments

Production

Projects

Pesquisa

CACSDEnvironment

Technical

and cientific

publications

Figure 4 . theory-research-application context

This flexibility and conceptual concept is theproduct resulting from integration methodology, ina friendly environment, with powerful tools tosupport all Control Systems Development Cycle(CSDC) [6], from the identification of systems tocontroller's synthesis. The CSDC is a methodologythat has driven the integration of tools that form theVIEnCoD, allowing the performance of a controlexperiment in all its stages, in a sequential or

independent way: process identification,controller's design and optimization, controller'ssimulation and implementation (Figure 5).

Optimization

Experimental Validation

ProblemReal

System

ControllerOk

Identification

Physicalmodel

Identification

MathematicalModel

Analysis

Tests

Implementation

ControllerDesign Analysis

Figure 5 . Development Cycle

Regarding the fast development, either intheoretical field (e.g.: new methods and controlalgorithms) as in hardware structures (acquisition

systems - instrumentation) and software (advancedgraphical resources and efficient computer system),the characterization of VIEnCoD is suggested as anOpen CACSD environment [16]. Open in thiscontext means :

The formulation of extreme different

nature systems, through standardizationand consistent description language, ispossible. The user is able to use existingmodel libraries, and also increment them;

Easy conversion and integration ofmodels;

For integrating programs, the user maydevelop its own application and establish a

standard interface and a specificenvironment for these components;

The environment must be enabled to

support interfaces with other applications.Data exchange must work both ways (bi-directionally);

Hardware platform exchange must besupported without conceptual changes andprotocol level transparency.

These requisites layout the architecture, theenvironment and software structure described inthe following.

3.1 VIEnCoD Architecture

The hardware support (interface with physicalelements) is provided by the VirtualInstrumentation concept through theLabWindows/CVI platform, providing idealconditions for development and configuration ofelectronic instrumentation (VXIbus, DAQboards,...etc), communication systems withindustrial elements (CLP, Fieldbus, Profibus,...etc)and Internet (TCP/IP), adequate to the needs ofthecontrol project. The LabWindows/CVI 4.0 iscompatible with most of the C/C++ 32-bitdevelopment environments for Windows. Thisallows the opening for interchange of the sourcecode and developed libraries.

The analytical and mathematical support isprovided by Matlab and Simulink tools that areintegrated and administrated at VIEnCoD, in atransparent way, along with LabWindowsresources. For support to CSDC the followingMatlab components are necessary : Simulink,System Identification Toolbox, Control SystemsToolbox, Optimization Toolbox / NonlinearControl Design Blockset, Matlab Compiler andReal Time Workshop.


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The Matlab Compiler allows Toolboxalgorithms and routines, further than programsgenerated by the user, under m-function, to betranslated from Matlab code into ANSI C code. Inanalog way, the Real Time Workshop translates theMatlab codes of block diagrams, implemented atSIMULINK, for the ANSI C code. This allows the

interpretation of these resources by the VirtualInstrumentation environment provided byLabWindows/CVI (hardware support).

The integration methodology of these tools isthe basis of the VIEnCoD conception and isillustrated in Figure 6. It is important to highlightthe opening regarding interface(hardware/communication) with application andlayout or industrial process.

LabWindows/CVI Matlab - Simulink

OTIMIZAO

REALIZAO EXPERIMENTALIDENTIFICAO

M odelo F s ic o I dent if ic a o

ModeloMatemtico

Anlise

Testes

Implementao

Projeto doControlador

Anlise

SistemaReal

Problema ControladorOK

datafiles

codes

Plant or Process

Real Time Conditions

HW - Open platform protocol/drivers (communication)

Condies de tempo real

Methodology

Offline simulation

statuscommands

vECU

virtual Electronic

Control Unit

SupervisionSystems

Figure 6 . Concept of VIEnCoD

The VIEnCoD architecture was, therefore, theresult of studies including features and resourcesavailable in LabWindows/CVI and Matlab-Simulink platforms, in a way to allow theintegration of a specific development environmentof virtual instrumentation for an analysisenvironment and control systems project. Thisintegrated environment must be under real timeconditions, allowing simulations such as

Hardware-in-the-loop (HIL). This concept, HIL,designates a simulation in which the obtainedcontroller at the CSDC is physically implementedby the VIEnCoD, with the layout or the real

process included in the control loop [11].

The vECU (Virtual Electronic Control Unit) is

the denomination of all support structure for thesimulation with HIL, which is formed by hardwareelements (acquisition platform and controller) andsoftware (supervision and control ofinstrumentation and controller implementation).The conception of the VIEnCoD determines thevECU hardware composition based on openinstrumentation platform and the PC (processor) as

controller. In this hardware is where the softwareelements are processed: applications developed invirtual instrumentation environment for monitoringand controlling instrumentation and support forcontrol law, under validation process. Bothprocesses operate in real time conditions underWindows operational environment through RTX

(Real Time Extension for Windows). Figure 7illustrates this structure. This caracteristic allowsthe installation of the VIEnCoD in computerswithout restricted and expensive specifications ofhardware (processeur and acquistion system),according to education needs.

OFFLINE process

Identification

Optimization

ModelsSimulation

Plant

[a1...an b1...bm]

[Kp Td Ti]

[U Y]

0 1 0 2 0 3 0 4 0 5 0 6 0 7 0 8 03

4

5

6

7

Output#1

Input and output signals

0 1 0 2 0 3 0 4 0 5 0 6 0 7 0 8 03

4

5

6

7

Time

Input#1

u(k)=a1.u(k-1)+...+an.u(k-n)+ b1.e(k)+...+bm.u(k-m)

ONLINE process

Control strategieWindows 95/NT

Ts

RTX

ECUVI

ECUVI

Ts

Figure 7 : Operation structure of VIEnCoD

3.2 VIEnCoD Environment

The VIEnCoD multifunctional proposalrequires that its user interface (GUI GraphicalUser Interface) synthesize all theoretical controlstructure linked to CSDC phases, enablingresources in a clear and intuitive way, with easyperception of objectives. The methodology adoptedwas suggested in [17] and referred to in someworks such as [12] [1], with necessary adaptations

for the proposed objectives. A similar approach isfound in [13] where contributions are also found. In

the latter the global environment structure mustcontain :

Familiarity : same layout profile amonginterfaces;

Concentration : one idea per module. Theidea corresponds to a specific CSDC stage(or a task of this stage);

Simplicity : the interface must presentitself in a clear and direct way, displayingsense of unity. Functionality must only beadded to the interface if really necessaryto the group.

All VIEnCoD is administered through a mainGUI that takes the role of representing and makingavailable all CSDC stages, in a clear and intuitiveway, as shown in Figure 8. Its structure can bedivided, basically, in four functional groups : (i)modeling and support for representation of


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systems, (ii) identification, (iii) Optimization ofcontroller design, (iv) Controller's synthesis simulation with HIL.

Figure 8 . Main GUI and the dynamic tree.

This is done through dedicated menus andsubmenus with specific tasks for each stage and

also with the dynamic tree technique. Thistechnique is the adaptation of the methodologysuggested by [3] where all theoretical controlcontents supported by the software is presentedunder the shape of a diagram where each topic isrepresented by a pushbutton that executes specificGUIs or screens with theoretical contents(hypertext). Modeling and analysis tools (answer tothe step, goat diagram, continuous/discretesystems,... etc) can be accessed through structurally

buttons placed in the layout that provides a globalvision of the system. In an environment withCACSD proposal, the dynamic tree is aninteresting resource to follow the CSDC project,

visualizing available stages and tools, at the sametime the user receives information about its logicaland sequential structure through dynamic enablingof pushbuttons for the accomplishment of stages.

Figure 9 . Plant and control interface, HIL

simulation

Virtual instrumentation resources can beaccessed at any CSDC stage. Figure 9 illustrates aGUI enabling some tasks, such as: reading andwriting of data, graphic visualization of results,configuration of instrumentation, layout andcontroller, HIL simulation. This modularity alsoallows this tool to be individually accessed for

testing external controllers. The implementation ofseveral conventional controllers structures (PID,advance) are allowed - as well as other controllingstrategies defined by professors, researchers orprofessionals, such as adaptive controllingstrategies, fuzzy controller, among others.

3.3 Estrutura de software do Toolbox

VIEnCoD

The VIEnCoD software structure was designed

in a way to provide support to the CSDCpreviously described under the exposed functionalrequirements. Figure 10 presents this structure

where the main data flow strictly follows theproposed methodology. In this figure allenvironment functional blocks are shown(applications or operational resources) as well asdata structures related in an organization defined by

CSDC stages.

It is important to stress that data in the mainflow are represented by temporary files that are areflection of the files already stored in the user'sbinder. This way, at the closing of the user's projectname.prj the processed information is storedalong with CSDC status (which stage in whichtask) allowing the following return, with

transparency, for retrieving data.

4. Proposta de integrao eperspectivas

The above mentioned projects presentfundamental contributions for the knowledge ofcontrol engineering and its topics. At ACONSYSthe methodological process for acknowledgementof the matter is analyzed with the purpose ofproviding solutions for deficiencies raised withincourses ministered at PUCPR's engineering schoolby providing a modular, flexible and interactiveenvironment. The professor encounters an

environment that allows support and enrichment oftheoretical contents exposed during classes,reflecting its purposes and structure. This way, thestudent is provided with a tool that allows him/herto understand the contents, eliminating doubts andcreating new situations for analysis according tohis/her acknowledgement pace. The return of thisacknowledge allows the professor to make a newevaluation regarding contents evolution.


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[2] C. Jinfang et al., Teaching Experiences ofServo Systems Experiments, Proceedings of 3t hIFAC Advances in Control Education, pp. 13-15,August, Japan, 1994.

[3] D. Munteanu, F. Michau, S. Gentil,Autodidact: a Simulation-based Learning

Environment in Automatic Control, Proceedingsof the 3rd European Control Conference, Belgium,1997.

[4] D. M. Zhang, L. Alem, Management ofExercise-Based Training Process IEEEConference on Systems Man and Cybernetics, vol4, pp. 2910-2915, 1996.

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61-68, Out., Brazil, 1995.[6] E. F. R. Loures, M. A. Busetti, VIEnCoD -Proposal of an environment CACSD in the Supportto the Control System Development Cycle based on

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[7] E. L. Borges, Da Simulao Criao deModelos - Um Contexto para a Aprendizagem naEmpresa. Proceedings of the VI SimpsioBrasileiro de Informtica na Educao, pp. 154-165, November, Florianpulis, SC, Brazil, 1995.

[8] G. Bormida et al., Learning Enviroment forDigital Electronics, IEEE Conference on SystemsMan and Cybernetics, vol. 4,pp. 2892-2897, 1996.

[9] G. H. R. Santos et al., SASHE: Autoria deAplicaes Hipermdia para o Ensino, Proc. of8th Brazilian Informtics and Education Symp.,pp.425 440, So Jos dos Campos, SP, Brazil,1997.

[10] H. F. Eberspcher, J. H. Jamur, M. Eleuterio,Using a web-based learning environment fordistance education, International Conference onEngineering and Computer Education (ICECE),Rio de Janeiro, 1999.

[11] H. Hanselmann, Hardware-in-the-LoopSimulation Testing and its Integration into aCACSD Toolset, The IEEE InternationalSymposium on Computer-Aided Control SystemDesign, September 15-18, 1996, Dearborn,Michigan USA, 1996.

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Automation Teaching Methodology: TheConception of a Didactic Laboratory, 14th WorldCongress of International Federation of AutomaticControl, Beijing China, 1999.

[14] R. C. Garcia, B. S. Heck, An InteractiveTool for Classical Control Design Education.Proceedings of the American Control Conference,San Diego, CA, pp. 1460-1464, 1999.

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[17] The MathWorks, Building GUIs withMatlab. USA: The MathWorks, 1997.


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