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    SSeennssoorrss && TTrraannssdduucceerrss

    Volume 121, Issue 10,September 2010

    www.sensorsportal.com ISSN 1726-5479

    Editors-in-Chief: professor Sergey Y. Yurish, tel.: +34 696067716, fax: +34 93 4011989, e-mail:[email protected]

    Editors for Western Europe

    Meijer, Gerard C.M.,Delft University of Technology, The Netherlands

    Ferrari, Vittorio, Universit di Brescia, Italy

    Editor South America

    Costa-Felix, Rodrigo, Inmetro, Brazil

    Editor for Eastern EuropeSachenko, Anatoly, Ternopil State Economic University, Ukraine

    Editors for North America

    Datskos, Panos G., Oak Ridge National Laboratory, USA

    Fabien, J. Josse, Marquette University, USA

    Katz, Evgeny, Clarkson University, USA

    Editor for Asia

    Ohyama, Shinji, Tokyo Institute of Technology, Japan

    Editor for Asia-Pacific

    Mukhopadhyay, Subhas, Massey University, New Zealand

    Editorial Advisory Board

    Abdul Rahim, Ruzairi, Universiti Teknologi, Malaysia

    Ahmad, Mohd Noor, Nothern University of Engineering, Malaysia

    Annamalai, Karthigeyan, National Institute of Advanced Industrial Science and

    Technology, JapanArcega, Francisco, University of Zaragoza, Spain

    Arguel, Philippe, CNRS, France

    Ahn, Jae-Pyoung, Korea Institute of Science and Technology, Korea

    Arndt, Michael, Robert Bosch GmbH, Germany

    Ascoli, Giorgio, George Mason University, USA

    Atalay, Selcuk, Inonu University, Turkey

    Atghiaee, Ahmad, University of Tehran, Iran

    Augutis, Vygantas, Kaunas University of Technology, Lithuania

    Avachit, Patil Lalchand, North Maharashtra University, India

    Ayesh, Aladdin, De Montfort University, UK

    Bahreyni, Behraad, University of Manitoba, Canada

    Baliga,Shankar, B., General Monitors Transnational, USA

    Baoxian, Ye, Zhengzhou University, China

    Barford, Lee, Agilent Laboratories, USA

    Barlingay, Ravindra, RF Arrays Systems, India

    Basu, Sukumar, Jadavpur University, India

    Beck, Stephen, University of Sheffield, UKBen Bouzid, Sihem, Institut National de Recherche Scientifique, Tunisia

    Benachaiba, Chellali, Universitaire de Bechar, Algeria

    Binnie, T. David, Napier University, UK

    Bischoff, Gerlinde, Inst. Analytical Chemistry, Germany

    Bodas, Dhananjay, IMTEK, Germany

    Borges Carval, Nuno, Universidade de Aveiro, Portugal

    Bousbia-Salah, Mounir, University of Annaba, Algeria

    Bouvet, Marcel, CNRS UPMC, France

    Brudzewski, Kazimierz, Warsaw University of Technology, Poland

    Cai, Chenxin, Nanjing Normal University, China

    Cai, Qingyun, Hunan University, China

    Campanella, Luigi, University La Sapienza, Italy

    Carvalho, Vitor, Minho University, Portugal

    Cecelja, Franjo, Brunel University, London, UK

    Cerda Belmonte, Judith, Imperial College London, UK

    Chakrabarty, Chandan Kumar, Universiti Tenaga Nasional, Malaysia

    Chakravorty, Dipankar, Association for the Cultivation of Science, IndiaChanghai, Ru, Harbin Engineering University, China

    Chaudhari, Gajanan, Shri Shivaji Science College, India

    Chavali, Murthy, N.I. Center for Higher Education, (N.I. University), India

    Chen, Jiming, Zhejiang University, China

    Chen, Rongshun, National Tsing Hua University, Taiwan

    Cheng, Kuo-Sheng, National Cheng Kung University, Taiwan

    Chiang, Jeffrey (Cheng-Ta), Industrial Technol. Research Institute, Taiwan

    Chiriac, Horia, National Institute of Research and Development, Romania

    Chowdhuri, Arijit, University of Delhi, India

    Chung, Wen-Yaw, Chung Yuan Christian University, Taiwan

    Corres, Jesus, Universidad Publica de Navarra, Spain

    Cortes, Camilo A., Universidad Nacional de Colombia, Colombia

    Courtois, Christian, Universite de Valenciennes, France

    Cusano, Andrea, University of Sannio, Italy

    D'Amico, Arnaldo, Universit di Tor Vergata, Italy

    De Stefano, Luca, Institute for Microelectronics and Microsystem, Italy

    Deshmukh, Kiran, Shri Shivaji Mahavidyalaya, Barshi, IndiaDickert, Franz L., Vienna University, Austria

    Dieguez, Angel, University of Barcelona, Spain

    Dimitropoulos, Panos, University of Thessaly, Greece

    Ding, Jianning, Jiangsu Polytechnic University, China

    Djordjevich, Alexandar, City University of Hong Kong, Hong Kong

    Donato, Nicola, University of Messina, Italy

    Donato, Patricio, Universidad de Mar del Plata, Argentina

    Dong, Feng, Tianjin University, China

    Drljaca, Predrag, Instersema Sensoric SA, Switzerland

    Dubey, Venketesh, Bournemouth University, UK

    Enderle, Stefan, Univ.of Ulm and KTB Mechatronics GmbH, GermanyErdem, Gursan K. Arzum, Ege University, Turkey

    Erkmen, Aydan M., Middle East Technical University, Turkey

    Estelle, Patrice, Insa Rennes, France

    Estrada, Horacio, University of North Carolina, USA

    Faiz, Adil, INSA Lyon, France

    Fericean, Sorin, Balluff GmbH, Germany

    Fernandes, Joana M., University of Porto, Portugal

    Francioso, Luca, CNR-IMM Institute for Microelectronics and Microsystems,

    Italy

    Francis, Laurent, University Catholique de Louvain, Belgium

    Fu, Weiling, South-Western Hospital, Chongqing, China

    Gaura, Elena, Coventry University, UK

    Geng, Yanfeng, China University of Petroleum, China

    Gole, James, Georgia Institute of Technology, USA

    Gong, Hao, National University of Singapore, Singapore

    Gonzalez de la Rosa, Juan Jose, University of Cadiz, Spain

    Granel, Annette, Goteborg University, SwedenGraff, Mason, The University of Texas at Arlington, USA

    Guan, Shan, Eastman Kodak, USA

    Guillet, Bruno, University of Caen, France

    Guo, Zhen, New Jersey Institute of Technology, USA

    Gupta, Narendra Kumar, Napier University, UK

    Hadjiloucas, Sillas, The University of Reading, UK

    Haider, Mohammad R., Sonoma State University, USA

    Hashsham, Syed, Michigan State University, USA

    Hasni, Abdelhafid, Bechar University, Algeria

    Hernandez, Alvaro, University of Alcala, Spain

    Hernandez, Wilmar, Universidad Politecnica de Madrid, Spain

    Homentcovschi, Dorel, SUNY Binghamton, USA

    Horstman, Tom, U.S. Automation Group, LLC, USA

    Hsiai, Tzung (John), University of Southern California, USA

    Huang, Jeng-Sheng, Chung Yuan Christian University, Taiwan

    Huang, Star, National Tsing Hua University, Taiwan

    Huang, Wei, PSG Design Center, USAHui, David, University of New Orleans, USA

    Jaffrezic-Renault, Nicole, Ecole Centrale de Lyon, France

    Jaime Calvo-Galleg, Jaime, Universidad de Salamanca, Spain

    James, Daniel, Griffith University, Australia

    Janting, Jakob, DELTA Danish Electronics, Denmark

    Jiang, Liudi, University of Southampton, UK

    Jiang, Wei, University of Virginia, USA

    Jiao, Zheng, Shanghai University, China

    John, Joachim, IMEC, Belgium

    Kalach, Andrew, Voronezh Institute of Ministry of Interior, Russia

    Kang, Moonho, Sunmoon University, Korea South

    Kaniusas, Eugenijus, Vienna University of Technology, Austria

    Katake, Anup, Texas A&M University, USA

    Kausel, Wilfried, University of Music, Vienna, Austria

    Kavasoglu, Nese, Mugla University, Turkey

    Ke, Cathy, Tyndall National Institute, Ireland

    Khelfaoui, Rachid, Universit de Bechar, AlgeriaKhan,Asif, Aligarh Muslim University, Aligarh, India

    Kim,Min Young, Kyungpook National University, Korea South

    Ko,Sang Choon, Electronics. and Telecom. Research Inst., Korea South

    Kockar, Hakan, Balikesir University, Turkey

    Kotulska, Malgorzata, Wroclaw University of Technology, Poland

    Kratz, Henrik, Uppsala University, Sweden

    Kumar, Arun, University of South Florida, USA

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    Kumar, Subodh, National Physical Laboratory, India

    Kung, Chih-Hsien, Chang-Jung Christian University, Taiwan

    Lacnjevac, Caslav, University of Belgrade, Serbia

    Lay-Ekuakille, Aime, University of Lecce, Italy

    Lee, Jang Myung, Pusan National University, Korea South

    Lee, Jun Su, AmkorTechnology, Inc. South Korea

    Lei, Hua, National Starch and Chemical Company, USA

    Li, Genxi, Nanjing University, China

    Li, Hui, Shanghai Jiaotong University, China

    Li, Xian-Fang, Central South University, China

    Liang, Yuanchang, University of Washington, USA

    Liawruangrath, Saisunee, Chiang Mai University, Thailand

    Liew, Kim Meow, City University of Hong Kong, Hong Kong

    Lin, Hermann, National Kaohsiung University, TaiwanLin, Paul, Cleveland State University, USA

    Linderholm, Pontus, EPFL - Microsystems Laboratory, Switzerland

    Liu, Aihua, University of Oklahoma, USA

    Liu Changgeng, Louisiana State University, USA

    Liu, Cheng-Hsien, National Tsing Hua University, Taiwan

    Liu, Songqin, Southeast University, China

    Lodeiro, Carlos, University of Vigo, Spain

    Lorenzo, Maria Encarnacio, Universidad Autonoma de Madrid, Spain

    Lukaszewicz, Jerzy Pawel, Nicholas Copernicus University, Poland

    Ma, Zhanfang, Northeast Normal University, China

    Majstorovic, Vidosav, University of Belgrade, Serbia

    Marquez, Alfredo, Centro de Investigacion en Materiales Avanzados, Mexico

    Matay, Ladislav, Slovak Academy of Sciences, Slovakia

    Mathur, Prafull, National Physical Laboratory, India

    Maurya, D.K., Institute of Materials Research and Engineering, Singapore

    Mekid, Samir, University of Manchester, UK

    Melnyk, Ivan, Photon Control Inc., CanadaMendes, Paulo, University of Minho, Portugal

    Mennell, Julie, Northumbria University, UK

    Mi, Bin, Boston Scientific Corporation, USA

    Minas, Graca, University of Minho, Portugal

    Moghavvemi, Mahmoud, University of Malaya, Malaysia

    Mohammadi, Mohammad-Reza, University of Cambridge, UK

    Molina Flores, Esteban, Benemrita Universidad Autnoma de Puebla, Mexico

    Moradi, Majid, University of Kerman, Iran

    Morello, Rosario, University "Mediterranea" of Reggio Calabria, Italy

    Mounir, Ben Ali, University of Sousse, Tunisia

    Mulla, Imtiaz Sirajuddin, National Chemical Laboratory, Pune, India

    Neelamegam, Periasamy, Sastra Deemed University, India

    Neshkova, Milka, Bulgarian Academy of Sciences, Bulgaria

    Oberhammer, Joachim, Royal Institute of Technology, Sweden

    Ould Lahoucine, Cherif, University of Guelma, Algeria

    Pamidighanta, Sayanu, Bharat Electronics Limited (BEL), India

    Pan, Jisheng, Institute of Materials Research & Engineering, SingaporePark, Joon-Shik, Korea Electronics Technology Institute, Korea South

    Penza, Michele, ENEA C.R., Italy

    Pereira, Jose Miguel, Instituto Politecnico de Setebal, Portugal

    Petsev, Dimiter, University of New Mexico, USA

    Pogacnik, Lea, University of Ljubljana, Slovenia

    Post, Michael, National Research Council, Canada

    Prance, Robert, University of Sussex, UK

    Prasad, Ambika, Gulbarga University, India

    Prateepasen, Asa, Kingmoungut's University of Technology, Thailand

    Pullini, Daniele, Centro Ricerche FIAT, Italy

    Pumera, Martin, National Institute for Materials Science, Japan

    Radhakrishnan, S. National Chemical Laboratory, Pune, India

    Rajanna, K., Indian Institute of Science, India

    Ramadan, Qasem, Institute of Microelectronics, Singapore

    Rao, Basuthkar, Tata Inst. of Fundamental Research, India

    Raoof, Kosai, Joseph Fourier University of Grenoble, France

    Reig, Candid, University of Valencia, Spain

    Restivo, Maria Teresa, University of Porto, Portugal

    Robert, Michel, University Henri Poincare, France

    Rezazadeh, Ghader, Urmia University, Iran

    Royo, Santiago, Universitat Politecnica de Catalunya, Spain

    Rodriguez, Angel, Universidad Politecnica de Cataluna, Spain

    Rothberg, Steve, Loughborough University, UK

    Sadana, Ajit, University of Mississippi, USA

    Sadeghian Marnani, Hamed, TU Delft, The Netherlands

    Sandacci, Serghei, Sensor Technology Ltd., UK

    Schneider, John K., Ultra-Scan Corporation, USA

    Sengupta, Deepak, Advance Bio-Photonics, India

    Shah, Kriyang, La Trobe University, Australia

    Sapozhnikova, Ksenia, D.I.Mendeleyev Institute for Metrology, Russia

    Saxena, Vibha, Bhbha Atomic Research Centre, Mumbai, India

    Seif, Selemani, Alabama A & M University, USA

    Seifter, Achim, Los Alamos National Laboratory, USA

    Silva Girao, Pedro, Technical University of Lisbon, Portugal

    Singh, V. R., National Physical Laboratory, India

    Slomovitz, Daniel, UTE, Uruguay

    Smith, Martin, Open University, UK

    Soleymanpour, Ahmad, Damghan Basic Science University, Iran

    Somani, Prakash R., Centre for Materials for Electronics Technol., India

    Srinivas, Talabattula, Indian Institute of Science, Bangalore, India

    Srivastava, Arvind K., Northwestern University, USA

    Stefan-van Staden, Raluca-Ioana, University of Pretoria, South Africa

    Sumriddetchka, Sarun, National Electronics and Computer Technology Center,

    Thailand

    Sun, Chengliang, Polytechnic University, Hong-KongSun, Dongming, Jilin University, China

    Sun, Junhua, Beijing University of Aeronautics and Astronautics, China

    Sun, Zhiqiang, Central South University, China

    Suri, C. Raman, Institute of Microbial Technology, India

    Sysoev, Victor, Saratov State Technical University, Russia

    Szewczyk, Roman, Industrial Research Inst. for Automation and Measurement,

    Poland

    Tan, Ooi Kiang, Nanyang Technological University, Singapore,

    Tang, Dianping, Southwest University, China

    Tang, Jaw-Luen, National Chung Cheng University, Taiwan

    Teker, Kasif, Frostburg State University, USA

    Thirunavukkarasu, I., Manipal University Karnataka, India

    Thumbavanam Pad, Kartik, Carnegie Mellon University, USA

    Tian, Gui Yun, University of Newcastle, UK

    Tsiantos, Vassilios, Technological Educational Institute of Kaval, Greece

    Tsigara, Anna, National Hellenic Research Foundation, Greece

    Twomey, Karen, University College Cork, IrelandValente, Antonio, University, Vila Real, - U.T.A.D., Portugal

    Vanga, Raghav Rao, Summit Technology Services, Inc., USA

    Vaseashta, Ashok, Marshall University, USA

    Vazquez, Carmen, Carlos III University in Madrid, Spain

    Vieira, Manuela, Instituto Superior de Engenharia de Lisboa, Portugal

    Vigna, Benedetto, STMicroelectronics, Italy

    Vrba, Radimir, Brno University of Technology, Czech Republic

    Wandelt, Barbara, Technical University of Lodz, Poland

    Wang, Jiangping, Xi'an Shiyou University, China

    Wang, Kedong, Beihang University, China

    Wang, Liang, Pacific Northwest National Laboratory, USA

    Wang, Mi, University of Leeds, UK

    Wang, Shinn-Fwu, Ching Yun University, Taiwan

    Wang, Wei-Chih, University of Washington, USA

    Wang, Wensheng, University of Pennsylvania, USA

    Watson, Steven, Center for NanoSpace Technologies Inc., USA

    Weiping, Yan, Dalian University of Technology, ChinaWells, Stephen, Southern Company Services, USA

    Wolkenberg, Andrzej, Institute of Electron Technology, Poland

    Woods, R. Clive, Louisiana State University, USA

    Wu, DerHo, National Pingtung Univ. of Science and Technology, Taiwan

    Wu, Zhaoyang, Hunan University, China

    Xiu Tao, Ge, Chuzhou University, China

    Xu, Lisheng, The Chinese University of Hong Kong, Hong Kong

    Xu, Tao, University of California, Irvine, USA

    Yang, Dongfang, National Research Council, Canada

    Yang, Shuang-Hua, Loughborough University, UK

    Yang, Wuqiang, The University of Manchester, UK

    Yang, Xiaoling, University of Georgia, Athens, GA, USA

    Yaping Dan, Harvard University, USA

    Ymeti, Aurel, University of Twente, Netherland

    Yong Zhao, Northeastern University, China

    Yu, Haihu, Wuhan University of Technology, China

    Yuan, Yong, Massey University, New Zealand

    Yufera Garcia, Alberto, Seville University, Spain

    Zakaria, Zulkarnay, UniversityMalaysia Perlis, Malaysia

    Zagnoni, Michele, University of Southampton, UK

    Zamani, Cyrus, Universitat de Barcelona, Spain

    Zeni, Luigi, Second University of Naples, Italy

    Zhang, Minglong, Shanghai University, China

    Zhang, Qintao, University of California at Berkeley, USA

    Zhang, Weiping, Shanghai Jiao Tong University, China

    Zhang, Wenming, Shanghai Jiao Tong University, China

    Zhang, Xueji, World Precision Instruments, Inc., USA

    Zhong, Haoxiang, Henan Normal University, China

    Zhu, Qing, Fujifilm Dimatix, Inc., USA

    Zorzano, Luis, Universidad de La Rioja, Spain

    Zourob, Mohammed, University of Cambridge, UK

    Sensors & Transducers Journal (ISSN 1726-5479) is a peer review international journal published monthly online by International Frequency Sensor Association (IFSA).Available in electronic and on CD. Copyright 2010 by International Frequency Sensor Association. All rights reserved.

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    SSeennssoorrss && TTrraannssdduucceerrss JJoouurrnnaallCCoonntteennttss

    Volume 121Issue 10October 2010

    www.sensorsportal.com ISSN 1726-5479

    Research Articles

    Computational Sensor Network: Book ReviewSergey Y. Yurish................................................................................................................................. I

    ANN Modeling of a Chemical Humidity Sensing MechanismSouhil Kouda, Zohir Dibi, Fayal Meddour, Abdelghani Dendouga and Samir Barra........................ 1

    Design of Artificial Neural Network-Based pH EstimatorShebel A. Alsabbah, Maazouz A. Salahat and Mohammad K. Abuzalata......................................... 10Improved RBF Neural Network Based Soft Sensor: Application to the Optimal RobustCalibration of a Six Degrees of Freedom Parallel Kinematics ManipulatorDan Zhang and Zhen Gao.................................................................................................................. 18

    Real Time Interfacing of a Transducer with a Non-Linear Process using SimulatedAnnealingS. M. GirirajKumar, K. Ramkumar, Bodla Rakesh, Sanjay Sarma O. V. and Deepak Jayaraj .......... 29

    Visible and Near Infrared (VIS-NIR) Spectroscopy: Measurement and Prediction of SolubleSolid Content of AppleHerlina Abdul Rahim, Kim Seng Chia and Ruzairi Abdul Rahim. ............................................................................................................ 42

    Control System Design for Cylindrical Tank Process Using Neural Model Predictive ControlTechniqueM. Sridevi, P. Madhavasarma, S. Sundaram..................................................................................... 50

    Application of Genetic Algorithm for Tuning of a PID Controller for a Real Time IndustrialProcessS. M. Giri Rajkumar, Atal. A. Kumar, N. Anantharaman. ................................................................... 56

    Modeling and Control of Multivariable Process Using Intelligent Techniques

    Subathra Balasubramanian, Radhakrishnan T. K. ............................................................................. 68

    Limitations of Feedback, Feedforward and IMC Controller for a First Order Non-LinearProcess with Dead TimeMaruthai Suresh and Ranganathan Rani Hemamalini....................................................................... 77

    Embedded Based DC Motor Speed Control SystemChandrasekhar T., Nagabhushan Raju K., V. V. Ramana C. H., Nagabhushana KATTE and ManiKumar C.............................................................................................................................................. 94

    Real Time Implementation of a DC Motor Speed Control by Fuzzy Logic Controller and PIController Using FPGAG. Sakthivel, T. S. Anandhi, S. P. Natarajan...................................................................................... 106

    IDC Based Battery-free Wireless Pressure SensorJose G. Villalobos, Zhen Xu, and Yi Jia ............................................................................................. 121

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    Energy Efficient MAC for Wireless Sensor NetworksPekka Koskela, Mikko Valta and Tapio Frantti................................................................................... 133

    Authors are encouraged to submit article in MS Word (doc) and Acrobat (pdf) formats by e-mail: [email protected]

    Please visit journals webpage with preparation instructions: http://www.sensorsportal.com/HTML/DIGEST/Submition.htm

    International Frequency Sensor Association (IFSA).

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    Sensors & Transducers Journal, Vol. 121, Issue 10, October 2010,pp. 56-67

    56

    SSSeeennnsssooorrrsss &&& TTTrrraaannnsssddduuuccceeerrrsssISSN 1726-5479

    2010 by IFSA

    http://www.sensorsportal.com

    Application of Genetic Algorithm for Tuning of a PID

    Controller for a Real Time Industrial Process

    1S. M. Giri RAJKUMAR, 2Atal. A. KUMAR, 3N. Anantharaman1Department of Electronics and Instrumentation Engineering, School of Electrical and Electronics

    Engineering, SASTRA University, Thanjavur-613402, India2SASTRA University, Thanjavur - 613 402, India,

    3Department of Chemical Engineering, National Institute of Technology,

    Tiruchirappalli - 620 015, India

    E-mail: [email protected]

    Received: 14 September 2010 /Accepted: 18 October 2010 /Published: 26 October 2010

    Abstract: PID (Proportional Integral Derivative) controller has become inevitable in the process

    control industries due to its simplicity and effectiveness, but the real challenge lies in tuning them to

    meet the expectations. Although a host of methods already exist there is still a need for an advanced

    system for tuning these controllers. Computational intelligence (CI) has caught the eye of the

    researchers due to its simplicity, low computational cost and good performance, makes it a possible

    choice for tuning of PID controllers, to increase their performance. This paper discusses in detail about

    Genetic Algorithm (GA), a CI technique, and its implementation in PID tuning for a real time

    industrial process which is closed loop in nature. Compared to other conventional PID tuning methods,

    the result shows that better performance can be achieved with the proposed method.

    Copyright 2010 IFSA.

    Keywords: PID, CI, GA, REAL TIME SYSTEM.

    1. Introduction

    During the past decades, process control techniques in the industry have made great advances.

    Numerous control methods such as: adaptive control, predictive control, neural control and fuzzy

    control have been studied. Despite many efforts, the proportionalintegral derivative (PID) controller

    continues to be the main component in industrial control systems, included in the following forms:embedded controllers, programmable logic controllers and distributed control systems. The reason is

    that it has a simple structure which is easy to be understood by the engineers and it presents robust

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    performance within a wide range of operating conditions. Van Overschee and De Moor [1] report that

    80% of PID type controllers in the industry are poorly/less optimally tuned. They state that 30 % of the

    PID loops operate in the manual mode and 25 % of PID loops actually operate under default factory

    settings. Over the years, many techniques have been suggested for tuning of the PID parameters. In

    this context there are classical (Ziegler/Nichols, gain phase margin method, Cohen/Coon and pole

    placement) [2-5] and advanced techniques (minimum variance, gain scheduling and predictive)

    [6- 10]. Some disadvantages of these control techniques for tuning PID controllers are: (i) excessivenumber of rules to set the gains, (ii) in adequate dynamics of closed loop responses, (iii) difficulty to

    deal with nonlinear processes and (iv) mathematical complexity of the control design [10]. Therefore,

    it is interesting for academic and industrial communities the aspect of tuning PID controllers,

    especially with a reduced number of parameters to be selected and a good performance to be achieved

    when dealing with complex processes [9].

    During the last 25 years there has been significant developments in methods for model based control

    [11, 12]. A recent survey of evolutionary algorithms for control systems can be found in [13, 14].

    Among the techniques found out, intelligent techniques and computational optimization techniques

    have found themselves a place in tuning of the parameters. The intelligent techniques include Artificial

    Neural Networks (ANN), and Fuzzy Logic (FL) which have developed over the last ten years [15, 16].Neural and fuzzy logic mimic the functioning of human intelligence process [17]. Their real time

    implementation is quite difficult [18], and hence as a result of the above said problems optimization

    algorithms have received increasing attention by research community [19]. In recent years, there has

    been extensive research on heuristic stochastic search techniques for optimization of the PID gains

    [20, 21]. GA which is a part of evolutionary computation has shown to be a valuable and robust

    technique in assisting engineers to solve complex problems [22-25]. Even a simple GA can give a

    satisfactory result in a large variety of engineering optimization problem. Salhi gives a general

    overview [26] of heuristic search methods including GAs.

    Genetic Algorithm belonging to the family of evolutionary computational algorithms has been widely

    used in many control-engineering applications. It is implemented as a computer simulation in which a

    population of abstract representations, called chromosomes or the genotype or the genome, of

    candidate solutions, creatures, or phenotypes, to an optimization problem evolves towards better

    solutions [27]. It finds the optimal solution through cooperation and competition among the potential

    solutions. These algorithms are highly relevant for industrial applications, because they are capable of

    handling problems with non-linear constraints, multiple objectives, and dynamic components

    properties that frequently appear in real-world problems [28]. It is an adaptive search algorithm

    premised on the evolutionary ideas of natural selection. The basic concept of GA is designed to

    simulate processes in natural system necessary for evolution, specifically those that follow the

    principles first laid down by Charles Darwin of survival of the fittest. As such it represents an

    intelligent exploitation of a random search within a defined search space to solve a problem. [29]. Thenatural process of evolution is mimicked in the algorithm to produce the best solution after many

    cycles of cross-over, mutation and reproduction. The evolution usually starts from a population of

    randomly generated individuals and happens in generations. In each generation, the fitness of every

    individual in the population is evaluated, multiple individuals are stochastically selected from the

    current population (based on their fitness), and modified (recombined and possibly randomly mutated)

    to form a new population. The new population is then used in the next iteration of the algorithm.

    Commonly, the algorithm terminates when either a maximum number of generations has been

    produced, or a satisfactory fitness level has been reached for the population [30]. It is hence one of the

    most developing controller tuning techniques [31]. The results obtained by the proposed method are

    found better than the IMC techniques [32] in various aspects.

    In the proposed work we compare the time domain specifications, the values of the performance

    measures like integral of absolute error (IAE), the integral of time weighted square error (ITSE) and

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    the integral of square time error (ISTE) [6, 33] obtained by using the conventional techniques and our

    proposed method using genetic algorithm to prove that the proposed method is better than the

    conventional methods. In the section that follows we have given the explanation of the setup, a view of

    the conventional methods used, the proposed algorithm, the values obtained, the results and graphs and

    finally the conclusion.

    2. Industrial Process Based Closed Loop System

    The closed loop system that has been considered here is used to maintain the temperature in an

    agitated vessel. The agitator consists of three paddles which are connected to a vertical shaft. The shaft

    is connected to an electric motor. The agitator is used to mix two acids namely sulphuric acid (H2SO4)

    and oleum (H2S2O7). There are three inlets, for the inflow of sulphuric acid, oleum and steam. The

    steam is used to supply heat to the agitating vessel and maintain it at a temperature of 110-1300C. The

    steam is supplied from a 10 ton boiler through a regulator which supplies steam at a maximum

    pressure of about 5 kgf/cm2. The mixed acid solution is then sent to the reactor through an overhead

    pipeline. The steam from the boiler is sent through a pipeline. This line is connected as inlet to the

    control valve which controls the steam entering the agitated vessel. A resistance temperature detector(RTD) is used to measure temperature in vessel. The range of RTD used is 0-200

    0C. The output signal

    is conditioned and converted to a current signal, which is of the standard range of 4-20 mA. Here,

    4 mA corresponds to 00

    C and 20 mA corresponds to 2000C of RTD. The output signal is given to the

    host computer through the panel board of a Distributed Control System (DCS). Man-Machining

    Interface allows human interruption in the process whenever necessary through the host computer,

    which acts as a controller. Then the output signal from the computer is sent to a current to pressure

    (I/P) converter. The signal is a current signal of 4-20 mA, the I/P converter is a device which gives out

    pressurized air in the range of 3 15 psi to the control valve proportional to the current supply given to

    it. The control valve is of globe type which is used to control the steam supplied to the agitated vessel.

    The steam is supplied through metal pipes of about 2 diameter. When the pressure of the supply air to

    the control valve from the I/P converter is 15 psi the valve will be 100 % opened and when the

    pressure is 3 psi the valve will be 0 % opened. Thus the valve opening is proportional to the air

    pressure supplied to it. The steam supplied to the control valve is about 4-5 kgf/cm2, which increases

    the temperature suitably as per the requirement. The piping and instrument diagram of the process is

    shown in Fig. 1.

    Fig. 1. Piping and Instrument diagram of the industrial closed loop process.

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    The industrial process system is further considered as a closed loop system with the components

    having the specifications as indicated. Mathematical model for this process is estimated by considering

    a step change of 10 % to the steam valve, after putting the system in an open loop mode. The response

    curve was traced, and was found similar to be that of a FOPTD, and the mathematical model was

    found to be,

    )1328(468.0)(

    42

    sesG

    s (1)

    The model validation with its real time response is given in the Fig. 2.

    Fig. 2. Comparison of real time and model response for the industrial process.

    3. Non-Traditional Optimization Techniques

    The implementation of non-traditional optimization techniques for a process based on temperature as

    the variable to be controlled in a process industry has been attempted. A PID controller is proposed for

    the system, which fulfills the need for anticipatory control. PID controllers are also considered more

    suitable for temperature based processes. The transfer function of the process system based on the

    operating conditions was estimated as in equation 1.

    The conventional method chosen for the proposed work is called Internal Model Control (IMC)

    technique. The various formulae used for this method for tuning the PID controller are given in

    Table 1.

    Table 1. Tuning rules for IMC technique.

    Controller

    Type

    Controller Gain

    (no units)

    Integral Time

    (seconds)

    Derivative Time

    (seconds)

    PID

    control

    process dead time (seconds);process lag time (seconds);

    K = process gain (dimensionless);

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    used for aggressive but less robust tuning;

    used for more robust tuning.

    Some controller mechanisms use proportional band instead of gain. Proportional band is equal to

    100 divided by gain. The values in the table are for an ideal type controller. The controller computes

    controller gain, integral time, and derivative time using the formulas shown.

    4. Genetic Algorithm

    4.1. Introduction

    Genetic Algorithm form a class of adaptive heuristics, based on principles derived from the dynamics

    of natural genetics. The searching process simulates the natural evolution of biological creatures and

    turns out to be an intelligent exploitation of a random search. A candidate solution (chromosome) is

    represented by an appropriate sequence of numbers. In many applications the chromosome is simply a

    binary string of 0s and 1s. The quality of its fitness function evaluates a chromosome, with respect tothe objective function of the optimization problem. A selected population of solution (chromosome)

    initially evolves by employing mechanisms modeled similar to those used in Genetics. The Fig. 3

    presents the flowchart for Genetic Algorithm.

    Fig. 3. Flow chart for GA.

    4.2. GA Operators

    Reproduction

    Reproduction is the first operator applied on a population. Reproduction selects goods strings in a

    population and forms a mating pool and hence known as selection operator. There exist a number ofreproduction operators in GA, but the essential idea in all of them is to pick the above-average strings

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    from the current population and insert their multiple copies in the mating pool in a probabilistic

    manner.

    In this work,Rank Ordermethod is used as reproduction operator. The rank is given according to the

    fitness value of each chromosome. If fitness is more, higher the rank given, so that the probability (this

    is fixed for less rank and more for high rank) for selecting that particular string is more.

    The probability values for selection, according to

    (Max-Min)(Rank (i, t)-1)

    Expected value (i, t) = Min + ---------------------------------

    N-1

    Crossover

    In crossover, new strings are created by exchanging information among strings of the mating pool

    based on a probability Pc. Actually strings are picked from the mating pool and some portions of thestrings are exchanged between the strings. A string point crossover operator is used in this work which

    is performed randomly by choosing a crossing site along the string and by exchanging all bits in on the

    right side of the crossing site as shown.

    Before crossover: The crossover site is selected as 7th

    bit.

    After crossover:

    Crossover has been made between the strings after the 7th

    bit.

    Mutation

    The mutation operator changes 1 to 0 and vice versa with a small mutation probability P m. Here the

    operator performs a bit-wise mutation. The need for mutation is to create a point in the neighbor of the

    current point, thereby achieving a local search around the current solution. Mutation is also used to

    maintain diversity in the population.

    Before mutation:

    1101001000

    After mutation:

    1100001000 (here the mutation is carried out on the 4th bit)

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    5. Implementation of GA

    The optimal values of the conventional PID controller parameters Kp, Ki and Kd, is found using GA.

    All possible sets of controller parameter values are chromosomes whose values are adjusted so as to

    minimize the objective function, which in this case is the error criterion, which is discussed in detail.

    For the PID controller design, it is ensured the controller settings estimated results in a stable closedloop system subjected to constraints.

    5.1. Initialization of Parameters

    To start up with GA, certain parameters need to be defined. It includes the population size, bit length

    of chromosome, number of iterations, selection, crossover and mutation types etc. Selection of these

    parameters decides to a great extent the ability of designed controller. Initializing the values of the

    parameters for this work is as follows:

    Population size 100

    Bit length of the considered chromosome 6Number of Generations 100

    Selection method Rank method

    Crossover type Single point crossover

    Crossover probability 0.8

    Mutation type Uniform mutation

    Mutation probability 0.05

    5.2. Performance Index for the GA Algorithm

    The objective function considered is based on the error criterion. The performance of a controller is

    best evaluated in terms of error criterion. A number of such criteria are available and in this paper,

    controllers performance is evaluated in terms of Integral of Absolute Errors (IAE) criterion, given by

    equation 2.

    (2)

    The IAE weights the error with time and hence emphasizes the error values over arrange of 0 to T,where T is the expected settling time.

    6. Results and Comparison

    The implementation of GA is done to find the optimal PID controller parameters. They are plotted as

    the best values among the considered population size for all the iterations, and are given in Figs. 4-6.

    The PID controller parameters for this implementation is given as

    Kp= 24.87, Ki=0.069 and Kd= 483.85.

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    Fig. 4. Best solutions of Kp for 100 iterations for industrial process based on GA.

    Fig. 5. Best solutions of Ki for 100 iterations for industrial process based on GA.

    Fig.6. Best solutions of Kd for 100 iterations for industrial process based on GA.

    The PID controller is designed for an industrial closed loop process for which the control variable is

    temperature. The process is allowed to reach the steady state condition at 122 C , and the PID

    controller is studied for its response by giving a servo change in the control variable by 2C, making

    the new set point to be 124 C. The IMC controller is the best among the traditional techniques. Also,

    the various PID controller parameters considered for analysis in this section are shown in the below

    Table 2.

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    The response of the controlled variable was sketched for the proposed PID controller, and is presented

    in Fig. 7.

    Table 2. Various PID controller parameters for industrial process.

    Controllers IMC GA

    Proportional gain, Kp 3.620 24.870Integral gain constant, Ki 0.0103 0.0690

    Derivative gain constant, Kd 71.445 483.85

    Fig. 7. Comparative response of IMC, GA based controllers for industrial process.

    Based on these responses, the time domain specifications with relevance to the real time data, is noted

    and they are tabulated and presented in the Table 3.

    Table 3. Time domain specifications for industrial process system.

    IMC GA

    Inverse peak

    (degree)119.8 121.36

    Inverse peak

    time(seconds)360 300

    Rise time

    (seconds)2500 660

    Peak time

    (seconds) 2500 1020

    Overshoot

    (%)1.2 86.5

    Settling time

    (seconds)2500 1920

    The robustness investigation for the process is analyzed by calculating the performance index to the

    transfer function model whose parameters are deviated by 20 %. The altered model which possesses

    the uncertainties is given by,

    )16.393(

    561.0)(

    6.33

    s

    esG

    s

    (3)

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    The graph showing the variation of objective function as the iterations are carried on is shown below

    (Fig. 8).

    Fig.8. IAE values for 100 iterations for industrial process based on GA.

    The calculation of the performance index for the mentioned model with the proposed controllers are

    tabulated and presented in the Table 4.

    Table 4. Performance index for industrial process model.

    IMC GA

    ITAE 999.03 53.97

    IAE 948.11 162.55

    ISE 952.63 343.75

    MSE 0.0418 0.0151

    The response curve with the IMC controller has a larger negative peak as the delay is not properly

    taken care, whereas the GA controller is the best, proving to be a better one to achieve the set point.

    Also, the robustness investigation illustrates the proposed tuning techniques always have a lesser value

    than the traditional PID controller.

    7. Results

    The various results presented prove the betterness of the GA tuned PID settings than the IMC tuned

    ones. The simulation responses for the models validated reflect the effectiveness of the GA based

    controller in terms of time domain specifications. The performance index under the various error

    criterions for the proposed controller is always less than the IMC tuned controller. Above all the real

    time responses confirms the validity of the proposed GA based tuning for the industrial process

    considered.

    GA presents multiple advantages to a designer by operating with a reduced number of design methods

    to establish the type of the controller, giving a possibility of configuring the dynamic behavior of the

    control system with ease, starting the design with a reduced amount of information about the controller

    (type and allowable range of the parameters), but keeping sight of the behavior of the control system.These features are illustrated in this work by considering the problem of designing a control system for

    a plant of first-order system with time delay and deriving the possible results.

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