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Computer Simulation Supporting Control Engineering Teaching
Copyright © IFAC Advances in Control Education Oulu, Finland, 2003
ELSEVIER
IFAC PUBLICATIONS www.elsevier.comllocatelifac
COMPUTER SIMULA nON SUPPORTING CONTROL ENGINEERING TEACIDNG Leena Yliniemi and Kauko Leiviskii
University ofOulu, Control Engineering Laboratory, BOX 4300, FlN-90014 UNIVERSITY OF OULU .firS(lIamL'.-,u""Wll,~li.lJubl. fi
Abstract: Teaching is a very complex and demanding human activity. 1be computers together with network technology have made it possible to utilise computer based learning material for supporting the teaching of control engineering. This has been found also at the Control Engineering in the University of Oulu, where computer based learning material called CALEXX has been developed during many years. Especially interactive examples, animations and simulations make the understand~ of control engineering illustrative and easier, because the students can "experiment" with situations, which would be too expensive or too dangerous in real life. Different computer simulators have been developed for examining the operation and control of different processes as rotary drying in mining and mineral industty, plate rolling mill in steel industty, freeness control in grinding mill in pulp industty and PVC manufacturing in chemical industry. The simulators are running in a Windows PC in the MATLAB or MATLAB Web Server environments. The simulators are an important part of the training material CALEXX . Copyright © 2003IFAC Keywords: education, control engineering, simulators
which include both basic control engineering and advanced control theory as measurements, process dynamics and modelling, adaptive and intelligent Four process control methods and optimisation. simulators play important role in the training material. The simulators represent different industrial sectors as mining and mineral industry, steel industry, chemical industry and pulp and paper industry.
I . INTRODUCTION For effective and efficient teaching a co!llJllter has proved an excellent tool for visualizing control engineering. Therefore at the Control Engineering Laboratory in the University of Oulu computer based learning rnaterial has been developed during many years for supporting the teaching of control engineering. The training material called CALEXX has been originally developed in the beginning of 90's in an EU project and it was introduced for the first time in the paper by Y1iniemi eLai (1994). The material has been later completed and updated. It consists of several separate modules, the contents of
In this paper, a general look to the structure and contents of CALEXX is presented. However, the main interest focuses on the simulators in CALEXX.
41
2. OVERALL STRUCTURE OF THE TRAINING MA TERlAL CALEXX The trammg material CALEXX fonns an electronic library, which contains eight different modules " bookshelves". These bookshelves finther contain "books" as Too\Book calls it's files. Asymetrix Too\Book, later Multimedia Too\Book has been used as the main development tool. When the user comes to the system, the library book is opened. Figure I presents the layout of the library book. The eight bookshelves refer to eight training materia\ deals with:
2 3 4 5 6 7 8
topics
the
Process measurements Process dynamics and modelling Controller design and tuning Advanced control methods and optimisation Pulp mill and freeness control simulation PVC process control and simulation Plate rolling mill control and simulation Rotary dryer control and simulation
The number of books in eight bookshelves is more than one hundred, and the number of pages (computer screens) in the books is more than two thousands. The pages include different elements as hypertext, interactive and solved exercises, simulation models, animations and video sequences. 10 addition to the books in the bookshelves, the material includes two assistant books: "Introduction to the material" and "How to use" book which are common to the whole material.
Fig. 1. Library of the training material CALEXX.
A book is constructed so that the first page is a cover page containing the name of a book. This page is automatically wiped to left in order to get the second page, which is an index or navigation page. It contains the topics of a book.
The design of navigation is very challenging, when a hypermedia application is so large as CALEXX is: It can cause easily navigation problems including "lost in hyperspace"-feeling, having difficulty in gaining overview, not being able to find information that is known to exist and determining how much is left. For preventing "lost in hyperspace" -feeling several navigation tools as navigation buttons, a navigation menu, a map book, an index book and hot words have been used in the material. Also the background colour in the first page of a bookshelf is different in different bookshelves. Figures 2 and 3 show examples about information pages.
Fig.
42
2. Example CALEXX.
about
an
information
page
in
3.1 Contents of.freeness control simulator Freeness is determined as the measurement for the filtering ability of groundwood pulp in a grinding mill. The essential objective is to find out the best parameters so that the freeness stays constant at the desired level in spite of Yal)'ing operating conditions. The aim of th: control strategy is also to maximize the production in the grinding milL If the target freeness can not be reached within the energy limits of a grinder, then the grindstone must be sharpened
Fig.
3. Example CALEXX.
The temperature of grinding has a vel)' great effect on the type of pulp produced. Grinding temperature, when steadily maintained at any predetermined point, gives better control of consistency and freeness. This results in increased operating efficiency and maxinun production output with less power required per tal to produce it. Temperature control also prevents any sudden deluge of cold water on a hot grinding stone, thus minimizing temperature strains and increasing the length of service. The need for frequent burring of the stone is also reduced.
about an information page in
The typical layout is that the hypertext lies on the left side or in the upper part of the page and animations, figures, diagrams etc on the right side or in the bottom part of the page.
The operation of the simulator is based on the experimental model, where the production rate of the grinder has been presented as the fimction of grinder load and grindstone sharpness. Figure 4 presents the layout of the user interface with the operating curves
3. PROCESS SIMULATORS IN CALEXX The important part in the training material CALEXX forms four process simulators developed to different industrial sectors. The aim of the simulators is to ccamine and to visualize the operation of a process in open loop or in closed loop situations. The physical or experimental models are based on real processes used in companies or research institutes.
u tt.";, C. tit
u.. r
UAU.f ~ IjO:'"I fJlE!t€Y;; (J)II 1 ~ ~,Ot:""" ~ tlJl ' ~ ~ ' ~ j;~ .. r,.:: ~U-; C(tiTRo:.. ~l l ~))R ... Ii h,) ~r.orA ~O A"nC6" lirl ""t "
n·.
At first, each simulator includes quite detailed description about the process. The operation of the process can be simulated also without controL It makes e.g. possible to estimate the effect of the model parameters i.e. the sensitivity of the parameters on the process output. To the students at the Control Engintmng Laboratory it is important to understand the operation of the process, because the laboratory belongs to the Department of Process and Environmental Engineering. This means that the students get basic knowledge about different processes with good knowledge about control engin=ing.
::::pIIi ... I . . . !:t"' __.£'&~ .nI ; .
"~'t""'"
. t .... .--" • • ~ ..'h . . . r...1 ~.I ·. ~-;
.......
~ 1r~c:::l"' ; bI
f.lJ ..d
... .-(i
Fig. 4. The user interface of the freeness control simulator.
The controllers in the simulators are usually PI or PlO controllers. The student has to tune the controllers for achieving the optimal result The bookshelf "Controller design and tuning " gives more information from turing methods. The student can link to this bookshelf and further to the book concerning tuning methods. The simulators run in a Windows PC under MATLAB or MATLAB Web Server environments.
32 Contents ofpvc manufacturing simulator PVC (polyvinylchloride) is one of the few synthetic polymers that have wide application in commerce. Suspension polymerisation is the most important method to manufacture PVC. The manufacturing process can be divided into polymerisation, remaining gas removing, dzying of resulting polymer, product storing. The simulator is based on the experimental model of the temperature control in PVC polymerisation reactor. Deviations from the correct temperature of polymerisation have significant effects on the quality of PVc. The temperature control system of the
43
polymerisation reactor is based on cascade control, which contains a main controller and slave oontrollers. The simulation includes the following four steps:
2 3
4
presents the simulator"
of the
bookshelf
"Steel
Tune up the PlO controllers. Set up the optimal parameter values for the controllers. In the cascade control the slave controllers are tuned fim. Set up the values for process inputs. Simulate. Simulation is based on the calculations of heat to be needed and reaction conversion. Check the values for the process outputs. The final results are presented in the relation to the polymerisation time.
The operation of the simulator is divided int 0 three phases:
2 3
contents
Simulation from the beginning polymerisation Simulation from the steady state Examination of the results.
of
Fig. 6. The index page of the plate rolling simulator.
the
The simulator is based on the plate mill pass schedule calculation system. This model has been developed in the Finnish steel plant. The simulation is started by selecting a plate which it is wanted i.e. by giving the plate type and dimensions. The model selects the adequate slab from which the plate is rolled.
The simulator was originally developed in the MATLAB environment, but it was later translated to a web environment using a MATLAB Web Server. The process and its operation in the web environment has been described in detail in the thesis by Vandezande (2000) and in the paper by Lindfors eLaL(2000). Figure 5 descnbes the layout of manufacturing simulator with controllers.
the
Figure 7 presents the user interface of the simulator.
PVC
Fig. 5 The layout of the PVC manufacturing simulator with controllers.
3.3 Contents ofp/aJe rolling mill simulator The plate rolling mill simulator is quite versatile including in addition to the real simulator also the detailed description about the steel plant and the operation of the process itself with its instrumentation and control systems. Figure 6
Fig. 7. The user interface of the plate rolling mill simulator
44
3.4 ConJents of rotary dryer simulator
4. CONCLUSIONS
am
The rotary chyer simulator is used very actively in different courses given at the Control Engineering Laboratory. It depends on that the simulator describes the operation of the plant rotary dryer located in the laboratory. The model is based on heat and mass transfer equations.
It is well known that teaching is very demanding difficult task. For visualizing the teaching of control engineering computer based training material, especially computer animations and simulations help to tmderstand control engineering, because they make possible to experiment situations, which
The simulator includes both process simulation and control simulation. The operation of the process is examined by changing operation conditions or model parameters. Step disturbances to various inputs can be made. Different control systems have been constructed for the dryer. The students examine primarily the operation of PID control, but also fuzzy control and fuzzy control together with PID control can be examined.
The focus in this paper is aimed on the contents and use of the simulators. The structure and contents of the computer based training material CALEXX is described. The material includes eight modules called bookshelves, four modules of these include basic control engineering and advanced control methods and four process simulators, which represent different industrial sectors as mining and mineral, chemical, steel and pulp and paper industry. The material is nmniog in a Windows PC under Multimedia TooIBook. The simulators run under Matlab or MatlabWeb. Each simulator runs standalone. The use of simulators is free for the students in the Control Engineering Laboratory, but for others it is chargeable.
The simulator is described in detail in the thesis by Maes (1999). Figure 8 presents the contents of the rotary dryer simulator and Figure 9 the control interf.tce of the simulator.
REFERENCES lindfors, J., L. Yliniemi and 1(. Leiviskii (2000). Using WWW to support control engineering training. In: Preprints of l' Symposium on Advances in Control Education - ACE2000. Goald Coast, 17- 19 December, 2000 Maes, M. (1999). Modelling and Simulation of a Rotary Dryer . M.Sc.Thesis. Group T Leuven InstiMe ofTcchnology. Vandezande, L. (2000) Simulation of the temperature control system of a PVC suspension polymerisation reactor. M.Sc.Thesis. Group T Leuven Institute ofTcchnology. Yliniemi, L. and 1(. Leiviskii (1994). Training of Process Automation with Hypermedia. In: Preprints of 3rd Symposium on Advances in Control Education - ACE1994. Tokyo, 1-2 August, 2000.
Fig. 8. Index page of the rotary dryer simulator.
Fig. 9. Control interface of the rotary dryer simulator.
45
ELSEVIER
IFAC PUBLICATIONS www.elsevier.comllocatelifac
COMPUTER SIMULA nON SUPPORTING CONTROL ENGINEERING TEACIDNG Leena Yliniemi and Kauko Leiviskii
University ofOulu, Control Engineering Laboratory, BOX 4300, FlN-90014 UNIVERSITY OF OULU .firS(lIamL'.-,u""Wll,~li.lJubl. fi
Abstract: Teaching is a very complex and demanding human activity. 1be computers together with network technology have made it possible to utilise computer based learning material for supporting the teaching of control engineering. This has been found also at the Control Engineering in the University of Oulu, where computer based learning material called CALEXX has been developed during many years. Especially interactive examples, animations and simulations make the understand~ of control engineering illustrative and easier, because the students can "experiment" with situations, which would be too expensive or too dangerous in real life. Different computer simulators have been developed for examining the operation and control of different processes as rotary drying in mining and mineral industty, plate rolling mill in steel industty, freeness control in grinding mill in pulp industty and PVC manufacturing in chemical industry. The simulators are running in a Windows PC in the MATLAB or MATLAB Web Server environments. The simulators are an important part of the training material CALEXX . Copyright © 2003IFAC Keywords: education, control engineering, simulators
which include both basic control engineering and advanced control theory as measurements, process dynamics and modelling, adaptive and intelligent Four process control methods and optimisation. simulators play important role in the training material. The simulators represent different industrial sectors as mining and mineral industry, steel industry, chemical industry and pulp and paper industry.
I . INTRODUCTION For effective and efficient teaching a co!llJllter has proved an excellent tool for visualizing control engineering. Therefore at the Control Engineering Laboratory in the University of Oulu computer based learning rnaterial has been developed during many years for supporting the teaching of control engineering. The training material called CALEXX has been originally developed in the beginning of 90's in an EU project and it was introduced for the first time in the paper by Y1iniemi eLai (1994). The material has been later completed and updated. It consists of several separate modules, the contents of
In this paper, a general look to the structure and contents of CALEXX is presented. However, the main interest focuses on the simulators in CALEXX.
41
2. OVERALL STRUCTURE OF THE TRAINING MA TERlAL CALEXX The trammg material CALEXX fonns an electronic library, which contains eight different modules " bookshelves". These bookshelves finther contain "books" as Too\Book calls it's files. Asymetrix Too\Book, later Multimedia Too\Book has been used as the main development tool. When the user comes to the system, the library book is opened. Figure I presents the layout of the library book. The eight bookshelves refer to eight training materia\ deals with:
2 3 4 5 6 7 8
topics
the
Process measurements Process dynamics and modelling Controller design and tuning Advanced control methods and optimisation Pulp mill and freeness control simulation PVC process control and simulation Plate rolling mill control and simulation Rotary dryer control and simulation
The number of books in eight bookshelves is more than one hundred, and the number of pages (computer screens) in the books is more than two thousands. The pages include different elements as hypertext, interactive and solved exercises, simulation models, animations and video sequences. 10 addition to the books in the bookshelves, the material includes two assistant books: "Introduction to the material" and "How to use" book which are common to the whole material.
Fig. 1. Library of the training material CALEXX.
A book is constructed so that the first page is a cover page containing the name of a book. This page is automatically wiped to left in order to get the second page, which is an index or navigation page. It contains the topics of a book.
The design of navigation is very challenging, when a hypermedia application is so large as CALEXX is: It can cause easily navigation problems including "lost in hyperspace"-feeling, having difficulty in gaining overview, not being able to find information that is known to exist and determining how much is left. For preventing "lost in hyperspace" -feeling several navigation tools as navigation buttons, a navigation menu, a map book, an index book and hot words have been used in the material. Also the background colour in the first page of a bookshelf is different in different bookshelves. Figures 2 and 3 show examples about information pages.
Fig.
42
2. Example CALEXX.
about
an
information
page
in
3.1 Contents of.freeness control simulator Freeness is determined as the measurement for the filtering ability of groundwood pulp in a grinding mill. The essential objective is to find out the best parameters so that the freeness stays constant at the desired level in spite of Yal)'ing operating conditions. The aim of th: control strategy is also to maximize the production in the grinding milL If the target freeness can not be reached within the energy limits of a grinder, then the grindstone must be sharpened
Fig.
3. Example CALEXX.
The temperature of grinding has a vel)' great effect on the type of pulp produced. Grinding temperature, when steadily maintained at any predetermined point, gives better control of consistency and freeness. This results in increased operating efficiency and maxinun production output with less power required per tal to produce it. Temperature control also prevents any sudden deluge of cold water on a hot grinding stone, thus minimizing temperature strains and increasing the length of service. The need for frequent burring of the stone is also reduced.
about an information page in
The typical layout is that the hypertext lies on the left side or in the upper part of the page and animations, figures, diagrams etc on the right side or in the bottom part of the page.
The operation of the simulator is based on the experimental model, where the production rate of the grinder has been presented as the fimction of grinder load and grindstone sharpness. Figure 4 presents the layout of the user interface with the operating curves
3. PROCESS SIMULATORS IN CALEXX The important part in the training material CALEXX forms four process simulators developed to different industrial sectors. The aim of the simulators is to ccamine and to visualize the operation of a process in open loop or in closed loop situations. The physical or experimental models are based on real processes used in companies or research institutes.
u tt.";, C. tit
u.. r
UAU.f ~ IjO:'"I fJlE!t€Y;; (J)II 1 ~ ~,Ot:""" ~ tlJl ' ~ ~ ' ~ j;~ .. r,.:: ~U-; C(tiTRo:.. ~l l ~))R ... Ii h,) ~r.orA ~O A"nC6" lirl ""t "
n·.
At first, each simulator includes quite detailed description about the process. The operation of the process can be simulated also without controL It makes e.g. possible to estimate the effect of the model parameters i.e. the sensitivity of the parameters on the process output. To the students at the Control Engintmng Laboratory it is important to understand the operation of the process, because the laboratory belongs to the Department of Process and Environmental Engineering. This means that the students get basic knowledge about different processes with good knowledge about control engin=ing.
::::pIIi ... I . . . !:t"' __.£'&~ .nI ; .
"~'t""'"
. t .... .--" • • ~ ..'h . . . r...1 ~.I ·. ~-;
.......
~ 1r~c:::l"' ; bI
f.lJ ..d
... .-(i
Fig. 4. The user interface of the freeness control simulator.
The controllers in the simulators are usually PI or PlO controllers. The student has to tune the controllers for achieving the optimal result The bookshelf "Controller design and tuning " gives more information from turing methods. The student can link to this bookshelf and further to the book concerning tuning methods. The simulators run in a Windows PC under MATLAB or MATLAB Web Server environments.
32 Contents ofpvc manufacturing simulator PVC (polyvinylchloride) is one of the few synthetic polymers that have wide application in commerce. Suspension polymerisation is the most important method to manufacture PVC. The manufacturing process can be divided into polymerisation, remaining gas removing, dzying of resulting polymer, product storing. The simulator is based on the experimental model of the temperature control in PVC polymerisation reactor. Deviations from the correct temperature of polymerisation have significant effects on the quality of PVc. The temperature control system of the
43
polymerisation reactor is based on cascade control, which contains a main controller and slave oontrollers. The simulation includes the following four steps:
2 3
4
presents the simulator"
of the
bookshelf
"Steel
Tune up the PlO controllers. Set up the optimal parameter values for the controllers. In the cascade control the slave controllers are tuned fim. Set up the values for process inputs. Simulate. Simulation is based on the calculations of heat to be needed and reaction conversion. Check the values for the process outputs. The final results are presented in the relation to the polymerisation time.
The operation of the simulator is divided int 0 three phases:
2 3
contents
Simulation from the beginning polymerisation Simulation from the steady state Examination of the results.
of
Fig. 6. The index page of the plate rolling simulator.
the
The simulator is based on the plate mill pass schedule calculation system. This model has been developed in the Finnish steel plant. The simulation is started by selecting a plate which it is wanted i.e. by giving the plate type and dimensions. The model selects the adequate slab from which the plate is rolled.
The simulator was originally developed in the MATLAB environment, but it was later translated to a web environment using a MATLAB Web Server. The process and its operation in the web environment has been described in detail in the thesis by Vandezande (2000) and in the paper by Lindfors eLaL(2000). Figure 5 descnbes the layout of manufacturing simulator with controllers.
the
Figure 7 presents the user interface of the simulator.
PVC
Fig. 5 The layout of the PVC manufacturing simulator with controllers.
3.3 Contents ofp/aJe rolling mill simulator The plate rolling mill simulator is quite versatile including in addition to the real simulator also the detailed description about the steel plant and the operation of the process itself with its instrumentation and control systems. Figure 6
Fig. 7. The user interface of the plate rolling mill simulator
44
3.4 ConJents of rotary dryer simulator
4. CONCLUSIONS
am
The rotary chyer simulator is used very actively in different courses given at the Control Engineering Laboratory. It depends on that the simulator describes the operation of the plant rotary dryer located in the laboratory. The model is based on heat and mass transfer equations.
It is well known that teaching is very demanding difficult task. For visualizing the teaching of control engineering computer based training material, especially computer animations and simulations help to tmderstand control engineering, because they make possible to experiment situations, which
The simulator includes both process simulation and control simulation. The operation of the process is examined by changing operation conditions or model parameters. Step disturbances to various inputs can be made. Different control systems have been constructed for the dryer. The students examine primarily the operation of PID control, but also fuzzy control and fuzzy control together with PID control can be examined.
The focus in this paper is aimed on the contents and use of the simulators. The structure and contents of the computer based training material CALEXX is described. The material includes eight modules called bookshelves, four modules of these include basic control engineering and advanced control methods and four process simulators, which represent different industrial sectors as mining and mineral, chemical, steel and pulp and paper industry. The material is nmniog in a Windows PC under Multimedia TooIBook. The simulators run under Matlab or MatlabWeb. Each simulator runs standalone. The use of simulators is free for the students in the Control Engineering Laboratory, but for others it is chargeable.
The simulator is described in detail in the thesis by Maes (1999). Figure 8 presents the contents of the rotary dryer simulator and Figure 9 the control interf.tce of the simulator.
REFERENCES lindfors, J., L. Yliniemi and 1(. Leiviskii (2000). Using WWW to support control engineering training. In: Preprints of l' Symposium on Advances in Control Education - ACE2000. Goald Coast, 17- 19 December, 2000 Maes, M. (1999). Modelling and Simulation of a Rotary Dryer . M.Sc.Thesis. Group T Leuven InstiMe ofTcchnology. Vandezande, L. (2000) Simulation of the temperature control system of a PVC suspension polymerisation reactor. M.Sc.Thesis. Group T Leuven Institute ofTcchnology. Yliniemi, L. and 1(. Leiviskii (1994). Training of Process Automation with Hypermedia. In: Preprints of 3rd Symposium on Advances in Control Education - ACE1994. Tokyo, 1-2 August, 2000.
Fig. 8. Index page of the rotary dryer simulator.
Fig. 9. Control interface of the rotary dryer simulator.
45