FAULT DETECTION, ACCOMODATION AND ISOLATION FOR PAPER MILL INDUSTRIAL CONTROL PREM KUMAR A/L APASAMY UNIVERSITI TEKNOLOGI MALAYSIA 2 DEDICATION For the loved Father and Mother 3 ACKNOWLEDGEMENT My special thanks to Dr. Mohd Fauzi Othman for this guide and supervise along this research study. Special appreciation to Malaysian Newsprints Industries Sdn .Bhd (Maintenance Department) stuffs for the cooperation through out the research. And also not forget those who directly and indirectly help success this research program. 4 ABSTRAK Kerosakan instrumen di industri adalah gangguan untuk pengeluaran industri. In bukan sahaja gangguan kepada pengeluaran malah kepada pembaikpulihan. Gangguan in menyebabkan kehilangan pengeluaran and masa pengeluaran. Industri sedang berkembang pesat dan teknik baru diperlukan untuk mengesan kerosakan instrumen lebih awal sebelum ia rosak and menganggu pengeluaran industri. Teknik tradisional iaitu ‘Predictive Maintenance’ dan ‘Run to Fail’ tidak mempunyai ruang untuk peningkatan dari segi pengesanan kerosakan instrumen .Banyak kajian telah dilakukan dalam topik pengesanan kerosakan instrumen dan teknik baru Kecerdikan Palsuan ( Artificial Intelligent ) digunakan dalam pengesanan kerosakan instrumen. Dengan mengunakan parameter dan pemalar dari prosess dan instrumen, AI boleh di bina dan digunakan untuk melihat kebolehpercayaan teknik AI dalam pengesanan kerosakan instrumen. Kebolehan pengesanan teknik AI digunakan untuk mengukur kebolehan pengesanan kerosakan instrumen. 5 ABSTRACT Instrument fault in industries is an interruption to industries production and maintenance. Its cause loses of production and time .As industries growing faster and rapidly, there are a need of method to detect the fault of instrument before its can disturb the production of industries. Conventional technique such as Predictive Maintenance and Run to Fail not did not give much room in term of predictability of instrument fault. Many study and research done on the fault detection technique and new technique Artificial Intelligent technique (AI) application in fault detection be come one of major studies in research. Using the parameter and variable from process and instruments, AI can be constructed and applied to view the reliability of the AI technique in the fault detection method. The predictability of AI will be measure as performance indicator of fault detection. 6 CONTENT CONTENT CHAPTER 1 PAGE Declaration 1 Dedication 2 Acknowledgement 3 Abstrak 4 Abstract 5 CONTENT PAGE INTRODUCTION 13 1.0 Problem Statement 13 1.1 Objective 15 1.2 Scope Of Study 16 1.3 Thesis Outline 17 1.3.1 Chapter 1 – Introduction 17 1.3.2 Chapter 2 – Fault Detection of Servo 17 Valve in Paper Machine 1.3.3 Chapter 3 – Literature Review 17 1.3.4 Chapter 4 – Methodology 18 1.3.5 Chapter 5 – Result 18 1.3.6 Chapter 6 – Conclusion 18 7 2 FAULT DETECTION OF SERVO 19 VALVE IN PAPER MACHINE 2.0 Introduction To Servo valve and Paper Machine 19 2.1 Overview Paper Making Process 21 2.2 Back ground of Paper Machine and Servo valve 23 2.3 Nip Control 23 2.4 De-watering in the press section 23 2.5 Fault Detection Of Servo Valve 26 In Paper Machine Industries 2.5.1 Problem And Effect Of Servo 26 Valve In Paper Machine 2.5.2 3 Problem Of Servo Valve In Paper Machine 28 LITERATURE REVIEW 30 3.0 Method of solution for fault detection in process control. 30 3.1 Method of solution in similar research 33 RESEARCH METHODOLOGY 36 4.0 Methodology 36 4.1 Data and parameter acquisition from the real 37 4 plant or system 4.2 From Paper Making Manual 39 4.3 Knowledge from Instrument Personal 40 4.4 Introduction to Fuzzy Logic and Neuro fuzzy 40 4.4.0 43 Part In This Research 8 4.4.1 Fuzzy logic model 44 4.4.2 The Modeling Mamdani 44 4.4.3 Neuro Fuzzy Model 45 4.4.4 The Modeling Sugeno 45 4.4.5 The construction of Sugeno model in Mat lab 45 4.4.6 The construction of Mamdani model in Mat lab 61 4.4.7 The construction of Early Prediction model 73 in Mat lab 5 RESULTS 70 5.0 Result of Neuro Fuzzy 75 5.1 Result of Mamdani 83 5.2 Result of Prediction 85 5.3 Analysis 95 5.3.1 Fuzzy Logic 95 5.3.2 Neuro Fuzzy 96 5.3.3 Neuro Network 96 CONCLUSION 97 6 6.0 What have been done during this research 98 6.1 What have been gains from this research 99 6.2 Recommendation 101 6.3 Reference literature 102 9 TABLE LIST TABLE NUMBER TITLE PAGE Table 2.6 Syndromes of servo valve abnormal in paper making 27 Table 2.7 Common fault of servo valve. 29 Table 4.5 Output Assigned Table 46 Table 4.6 Data to Mat lab 46 Table 4.22 List of fault from Database report 62 Table 4.23 List of fault from Analysis 60 Table 4.24 Constructed rules base on knowledge of fault analysis 63 10 FIGURE LIST FIGURE NUMBER TITLE PAGE Figure 2.1 Paper Machine 21 Figure 2.2 Press Section 22 Figure 2.3 Nip between roller with piston 24 Figure 2.4 Hydraulically pressed shoe 25 Figure 2.5 Servo Valve 25 Figure 4.0 Fault detection research methodology 37 Figure 4.1 Record database 38 Figure 4.2 Darwin system 39 Figure 4.3 Fuzzy logic as in Mamdani concept 44 Figure 4.4 Block diagram of TS Fuzzy Modeling 45 Figure 4.7 Loaded data 47 Figure 4.8 Selection of Membership function 48 Figure 4.9 Trained data 49 Figure 4.10 The generated Sugeno model 50 Figure 4.11 The input membership of input 1 51 Figure 4.12 The input membership of input 2 52 Figure 4.13 The input membership of input 3 53 Figure 4.14 The output membership model generated 54 Figure 4.15 The output model rules generated 55 Figure 4.16 The output model rules generated in Rules Editor 56 Figure 4.17 The generated Sugeno Model Structure 57 11 Figure 4.18 The generated Sugeno Model from Surface viewer 58 Figure 4.19 The command to test the output of generated 59 Sugeno model Figure 4.20 The tested output generated in Mat Lab 60 Command Window Figure 4.21 Database report which will be report by 61 personal involve in troubleshoot Figure 4.25 Construction of the Mamdani model 64 Figure 4.26 Membership function for set point deviate from 65 Measure value in the Mamdani model Figure 4.27 Membership function for Measure value offset 66 set point from Mamdani model Figure 4.28 Membership function for output for electronic 67 card fault from Mamdani model Figure 4.29 Membership function for output for filter blockage 68 in Mamdani model Figure 4.30 Membership function for output for o ring breakage in 69 Mamdani model Figure 4.31 Apply the constructed Rules from Figure 4.24 70 into the Rules Editor in Mamdani model Figure 4.32 Ruler Editor generated by Mamdani model 71 Figure 4.33 Ruler Surface generated by Mamdani model 72 Figure 5.1 The output membership of Neuro Fuzzy 75 model generated Figure 5.2 The output Neuro Fuzzy model rules generated 76 Figure 5.3 The output Neuro Fuzzy model rules generated 77 in Rules Editor Figure 5.4 The generated Sugeno Model Structure 78 Figure 5.5 The generated Sugeno Model from Surface viewer 79 Figure 5.6 The command to test the output of generated 80 Sugeno model 12 Figure 5.7 Output generated by Sugeno model 81 Figure 5.8 To check with the output generated by Sugeno model 82 Figure 5.9 Output of Sugeno model rules 83 Figure 5.10 Output of Sugeno model rules 84 Figure 5.11 Comparison predicted data and actual data 85 Figure 5.12 Prediction Error of the neuro network 86 Figure 5.13 Comparison predicted data and actual data 87 Figure 5.14 Prediction Error of the neuro Network 88 Figure 5.15 Comparison predicted data and actual data 89 Figure 5.16 Prediction Error of the Neuro Network 90 Figure 5.17 Comparison predicted data and actual data 91 Figure 5.18 Prediction Error of the neuro Network 92 Figure 5.19 Comparison predicted data and actual data 93 Figure 5.20 Prediction Error of the neuro Network 94 13 CHAPTER 1 INTRODUCTION 1.0 Problem Statement Recent development shows advancement in maintenance tool for industries growth very fast. Many tool developed to help maintenance to carry out corrective maintenance and the preventive maintenance. This concept of corrective maintenance and preventive maintenance is highly used to make sure the instruments used in production industry working well during production. The next level need to be seen in this field to enable the instrument reliability during production is high. One of current research that used is the use of AI technique to identify the failing instrument before its disturbed the production. This research regarding the application of Neuro fuzzy in fault detection of fault in a paper mill process control. This research is to study and develop an early fault detection system of instrument. The instrument selected for this research is servo valve due to its critically use in paper mill. Conventional method is the preventive maintenance where checklist daily is used to see the functionality of the instrument in field. But the limitation 14 to this method is that analysis method is not good enough to see the future of the instrument s condition. The Neuro Fuzzy is an advance technique to analysis the instrument condition and capable to view the future of this instrument. Data available from servo valve itself output voltage, current & pressure, flow rate .Its comparable with indirect pressure measure system (Darwin system). All captured data will be applied in Neuro fuzzy for fault detection. Other parameter such as machine speed, product grade will be taken into account. Using this data the fault detection using Neuro Fuzzy can be develop and help the industrial to make production more reliable. 1.1 Objective 15 The objective of this research is to study servo valve fault occur in application in paper machine. Using the information from plant, observe the pattern and symptoms of failure in servo valve system in act. And study the method to apply the fault detection method in actual plant, By understand the changes of parameter in process and its effect in servo valve system in real application and the change that made by servo valve fault, servo valve fault detection using the Artificial Intellegent can be constructed .The constructed fault detection system will be analysis the performances of it and if given opportunity will be tested in lab or simulation. 1.2 Scope Of Study 16 The scope of research covers wide area of mechanical, electricelectronic, and instrument. Using proper guide, this can be narrow down to specific range of study. Study the servo valve system in paper mill application in term of mechanically ,electrically and process control .The literature studied is to understand the concept of the fault detection in process control and studied the proposed method for the fault detection . All the data regarding the servo valve relevant to study collected and analyzed. Analysis the related data and check the suitable Neuro Fuzzy method to be use in research. Develop the AI algorithm for the Neuro Fuzzy method and tested by simulation . 1.3 Thesis Outline 17 1.3.1 Chapter 1 – Introduction In this chapter the introduction to on the fault detection concept in industries. Also elaborated the problem that exist in current industries instrument maintenance area. The objective of the research and the scope of study involve in this research. 1.3.2 Chapter 2 – Fault Detection Of Servo Valve In Paper Machine Here the overview of process area with instrument involve in this research will be introduced. The problem – effect involve process and instrument will be explain in detail. 1.3.3 Chapter 3 – Literature Review Here the literature, journal and manual that were studied to guide this research done. There’re some literature that involve indirectly with this research, which give useful information for research. 1.3.4 Chapter 4 – Methodology 18 In this chapter, the step that have take to complete this research is elaborated. The introduction to the Artificial Intellegent technique that going to be constructed will be explained. And how this Artificial Intellegent technique is implement in Mat Lab will be explained. The construction of the Artificial Intellegent technique will be shown step by step. 1.3.5 Chapter 5 – Result In this chapter the output of the constructed Fuzzy Logic, Neuro – Fuzzy and Neuro Network will be shown and explained .The design will be simulated in Mat Lab software and the output of simulation will be shown here. 1.3.6 Chapter 6 – Conclusion Here the overall explanations of the research given. What have been done throughout the research and what has been gain by this research also elaborated in this part. 19 CHAPTER 2 FAULT DETECTION OF SERVO VALVE IN PAPER MACHINE 2.0 Introduction To Servo valve and Paper Machine The rapid growing industrial edge just have came by in our world .So much of advance in engineering and technology have help boost up the production speed and capacity of industry .In such world, the need to new invention and innovation is much need .The industrial have become bigger and faster. To aid the industry, a lot of research have going on .On of the most rapid growing area in industry, the defect of instrument and equipment can be find to interrupt the production of industry. Even in the most advance equipment, failure of instrument and equipment experienced, and cause a lot of unnecessary interrupt for production business .The common word used to describe the lost of production is known as the Down Time. The industry will always try to minimize this Down Time. 20 Traditionally, there is little method, which used to prevent or minimize the effect of instrument fault to the process industry. The most common as Predictive Maintenance or in short for is known as the PVM and also Run To Fail. The technical personal will go to and check on regular basis while taking some data regarding the equipment condition, such as Gauge reading, current reading and other. But often the technique is does not give a very good outcome because in use human where each personal might have different judgments on the condition of equipment while inspection carry out and human have too many variable which effecting their judgments. On other hand technique will help the technical personal to detect the symptoms of equipment failure by visual inspection and measurement off line when any abnormal finding is found. This technique does help to detect failure of equipment which cause sometime by external factors such temperature and vibration. But this technique does not help for online monitoring and inspection because human will get very fast tired if they were as to continuously monitoring and become bored very fast. But using human intelligent where any kind of change in the signal, we as human find it’s as easy to tell something is fault from our experience. But machine is unable to learn as human and don’t know what is wrong and normal. But using both of human ability to learn and machine, which have longer working hours, we can construct a system, which capable learn and react as human. This technique is known as the Artificial Intelligent. There are few Artificial Intelligent technique can be used to make a fault detection system. In this research the Fuzzy Logic, Neuro –Fuzzy and Neuro Network is introduced for the fault detection research. The use of AI technique is not something new in current technology. In the paper machine the use of servo valve was discussed as in the early chapter .The servo valve use in paper machine is to control the gap between two rollers with the actuation power of piston. 21 2.1 Overview Paper Making Process Figure 2.1 Paper Machine [12] Processes, which involve the making of dry paper in sheet, form using wood fiber or recycle paper. Supplying the stock will make paper or raw material and paper formation will take place in Paper Machine. The Paper Machine is a very large piece of machinery. A typical machine is about the length of two football pitches and around 4 meters wide. It can run up to speeds of 2000 m per minute - or 60 miles per hour! The machine itself consists of 7 distinct sections. The head box, wire, press section (As in Figure 2.2), dryer section, calendar and reel section. The first section of the machine is called the 'Wet End'. This is where the diluted stock first comes into contact with the paper machine. It is poured onto the machine by the head box, which is a collecting box for the dilute paper stock. A narrow aperture running across the width of the head box allows the stock to flow onto the wire with the fibers distributed evenly over the whole width of the paper machine. The machine is operated by computer control such as DCS (Distributed Control system). The computer will 22 monitor the paper for moisture content, weight etc and computer screens will show pictures of the process and should any adjustments need to be made, an alarm will sound. Figure 2.2 Press Section 23 2.2 Back ground of Paper Machine and Servo valve Servo valve use in paper making machine to control the gap (nip) between 2 rollers which dewatering paper run. Refer Figure 2.3 .The example paper machine in Malaysia is in MALAYSIAN NEWS PRINTS INDUSTRIES SDN.BHD (MNI) located in Temerloh, Pahang. The type Paper Machine use is the VOITH SULZER from Germany. The servo valve is used in wet end area to control the formation of paper between 2 roll. This Servo valve is a critical instrument where the failure of it can cause down time to the machine. Machine down mean lost of production time and cost. On this research, the fault detection applied using neuro - fuzzy techniques on to this servo valve system in order to find the fault earlier. This fault detection method not only can be use to reduce down time but also give maintenance people information which can be analysis to make this system more reliable and better. This project also allows more room for the research in fault detection in process control. 2.3 Nip Control Servo valve use in paper making machine to control piston, which set the gap (nip) between 2 rollers, which run dewatering in papermaking. 3 servo valve used to control the bottom roller nip pressure line in paper making machine. 24 The picture shows the overview of servo valve application in wet end in papermaking. This is the control loop to control the nip (gap between 2 roller). Paper with from sectio Top Wet Paper Dewatered Piston Bottom Figure 2.3 Nip between roller with piston 2.4 De-watering in the press section [11] After formation of the sheet, a process which determines the most important sheet properties, the paper sheet has to be further drained and compressed. In this next phase, mechanical pressure exerted vertically to the sheet surface is used to further increase the proportion of dry content. In the press section, the web runs between a series of rolls, which exert specifically set amounts of pressure. The water pressed out of the paper is absorbed by felts and transported off. Refer Figure 2.4 In recent years, shoe presses have been developed to increase the efficiency of the traditional roll presses. In these press units, one of the rolls is replaced by a hydraulically pressed shoe. This creates a bigger press nip, which makes the process more effective. 25 Figure 2.4: Hydraulically pressed shoe Figure 2.5: Servo Valve 26 2.5 Fault Detection Of Servo Valve In Paper Machine Industries 2.5.1 Problem And Effect Of Servo Valve In Paper Machine In paper making ,when the raw material known as stock which contain fiber and water have to pass thought nip between 2 roller , top and bottom in wet end press section. This process to run the dewatering process in paper. This is a part of paper formation. Dewatering is a process where water will be removed from formed paper stage by stage in press section. Paper will pass through 1st press, 2nd press, 3rd press and so on to 4th press to run through the de watering process each time pass the presses nip. Later paper will lost more water and moisture drastically when run thought the dryer section .Here the fine tuning of the moisture level in paper by control loop system .Because the speed of 2 roll very high and the gap nip size is very small, a very précised of control gap distance required. And due to the size and weight of rollers which is very large compared to the gap nip ,a high actuation power required to actuate the moving part of the piston which control the rollers distance .Due to a very high vibration and noise environment ,the best control for this nip control is the hydraulic pressure which move the piston. This piston will be move as precise as possible because the use of hydraulics or oil .Air or pneumatic can not give good control due air can be compress and unable to control for very small displacement and its depend on the temperature as well. The servo valve will control the hydraulic pressure supply to the piston and control this piston movement. This gives smooth movement and, 27 controllable displacement ,will the properties of oil is independent of external factor . Why use servo valve, its because of its robustness in industry application special for in heavy industries. The reliability and high durability is come with the price of servo valve. It s consume very little power and able to control in very fine measure of hydraulic pressure. Precision and accuracy of control is one of important reason, why its have been choose in paper mill control system. Its requires very little maintenance and its universal control where its can be control using 4 - 20 mA either from DCS or PLC or any other common control system and tools. The failure of servo valve function will cause upset in paper formation. Possibility of paper break happen in presses section is high. The other effect of servo valve fault to process paper making as below : Table 2.6 : Syndrome of servo valve abnormal in paper making: No Syndrome of servo valve abnormal in paper making: 1 Number of paper break high at wet end press section 2 Paper wrinkle at in some part on paper 3 Profile nip balance 4 Dewatering unbalance across roll 5 Unbalance moisture profile 6 Felt condition abnormal 7 Felt life span reduce 8 Paper formation unstable 9 Moisture control unstable 10 Steam control on dryer will change 28 2.5.2 Problem Of Servo Valve In Paper Machine The servo valve is an very robust instrument, but its still will fault due its have an electronic card which to receives signal from DCS or PLC .Its have oil filter internally where filter the oil that passing inside and be control to the piston. The oil circulation from oil tank to pump to servo valve and to piston again back to tank. This oil circulation will carry not only carry oil but also sometime particles such as rust, mud and other unwanted element in oil pipeline. This sometime will cause blockage to the oil line. And cause the internal filter in servo valve coated. But however if the hydraulic line is monitored frequently, the possibility of oil contamination can be avoided. The critical issue or problem of servo valve fault is when its internal card fault. Because it’s happen without any early sign that can be recognize by normal technical personal. Visual inspect is impossible. The failure due to electronic card is sometime very difficult to diagnosis compared to other type of fault. There in no indication in DCS or in servo valve itself. Its worse case if it’s an intermitted problem where sometime its give correct and incorrect reading .In some paper mill to detect the faulty of servo valve require and high sampling time .This is due to the DCS and PLC sampling time very slow and does not shows actual reading to operation or maintenance . In my research the servo valve data available in other resources ,data were collected from Darwin system, a system which used to monitor the performance servo valve with high sampling time. This give more accurate data regarding the symptoms that happen to the servo valve. Common fault of servo valve shown in table 2.7. 29 Table 2.7: Common fault of servo valve. Internal cause servo valve fault External cause servo valve fault Electronic card Hydraulic oil properties Cable connector Hydraulic oil temperatures properties o - ring Surrounding vibration Filter DCS system PLC system Hydraulic pump Pipeline condition There is some external factor that cause the servo valve control abnormal such as the oil pump which give the inlet pressure to servo valve and the oil properties. These symptoms also will be show in DCS or other system, which look as the servo valve fault. Fault of servo valve can be detect by the machine when upset happen to paper or abnormal changes happen to the paper. 30 CHAPTER 3 LITERATURE REVIEW There are some research that have been done as in related to this research thesis Fault detection and Isolation Paper Machine Instrument. There are suggested method which can be see from the literature that been studied for this research on fault detection and isolation in paper machine instrument. Its have guide the research process directly or in directly. 3.0 Method of solution for fault detection in process control. Here s the general literature study which related to the research. [6] Leon Reznik and Vladik Kreinovichis, studying a feasibility of fuzzy models application in measurement procedures .The problem measurement data fusion ,when the sources can provides prediction or combination sources .The data applied to fuzzy prediction models and been observed the outcome. 31 [7] Rajiv Sreedhar and Benito Fernandez. In his literature have presented the preliminary results regarding the design of neural network based adaptive fault detection method. The error between the actual system and model system will be applied to the observer to obtain accurate estimates of states or output. [8] Tracy Dalton in his literature, mentioning the type of fault, and method of diagnosis that can have been done . Its give more detail regarding fault detection method in general. [9] Reza Asgary and Karim Mohammadi proposed the use a probabilistic neural network for fault detection in MEMS .A fuzzy system is implement to improve performance of the network. [12]Erik Dahlquist ,Tomas Lindberg from Malardalen University in Integrated Process control, fault diagnostics ,optimization and production planning – Industrial , literatures the different types of diagnostics with respect to control sensors ,control loop and processes . [13]A.M.Bhagwat ,R.Srinivasan and P.R.Krishnaswamy from National University of Singapore ,fault detection approaches during transition based on a nonlinear process model ,and operating procedures . [14]Bruno HEIM, Sylvie CAUVIN, Sylviane GENTIL presents the diagnostics system with output on real data scenario and its tested on line on a FCC (Fluid Catalytic Cracking) pilot plant. 32 [15]Pascal Dufour ,Sharad Bhartiya ,Thomas J.English ,Edward P.Gatzke ,Prasad S .Dhurjati and Francis J.Doyle 3 , shows the diagnostics for fault detection and isolation in a continuous pulp digester with comparing for accuracy and real time data . [16]Dauren F .Akhmetov ,Tomofumi Miura ,Masataka Itou , Manabu Tamamori ,Hiroto Murabayashi and Yuichi Hamade attempts the intelligent system for unified point for learning process optimization .Also practical implementation of faults detection is demonstrated . [17] B.Jiang ,M.Staroswiecki and V.Cocquempot in paper discuss the fault diagnosis problem for nonlinear system with unknown parameters .Discussion on Strictly Positive Realness requirement and extension to fault cases .The DC motor will be experimented here. [18] Sheng Yung Chang, Cheng Ren Lin and Chuei Tin Chang in paper mention the Signed Directed Graphs (SDG) and Fuzzy Interference techniques for fault diagnosis. The fault derived from SDG model and encoded ,interfaced with fuzzy rules . [19] Piotr Kulczycki , used statistical interference system for fault detection and diagnosis also prediction . Using kernel estimator techniques, an output wide range of application will be produced. [20] Bentiz – Perez H and Rendon – Torres P approach Fuzzy ART2 network to study the on - line for the pattern recognition rather than faults detection. 33 [21] In Soo Lee ,Doug Hyung Lee ,Euy Soo Lee ,Sang Jin Park a predictive method of identifying the feed and product using neural network based software is proposed .Data preprocessing and post processing methods are utilized to enhance the predictability of the software sensor model. Although many research have been studied, few paper was view as to related to this research study. Its give some guide for this research directly and indirectly . 3.1 Method of solution in similar research Here some of the principles from literature is observed for this research. [1] Rolf Isermann and Mihaela Ulteru, proposed the unified frame for integration of different fault detection and decision techniques via approximate reasoning on analytical and heuristic fuzzified symptoms. [2] Rolf Isermann have elaborate regard the fault detection method ,fault diagnosis as using knowledge based fault detection which divided to analytical symptom generation and heuristic symptom generation, and knowledge based fault diagnosis . Model based fault detection and its method has been drop written here. Rolf Isermann mention fault diagnosis method, which used to 34 identify the fault, was based on the observed analytical and heuristic symptoms and heuristic knowledge on process. [3] Dr.Rahmat Shoureshi and team member ,s have proposed on line equipment diagnosis using artificial intelligent and non linear observer to prevent catastrophic failures I substation equipment ,and aid the preventive maintenance . [4] L.B.Palma ,F.J.Coito ,R.N.Silva ,shows the online model based procedure for fault detection and diagnosis of sensor and process faults in plant. The method was discuss here is based on parity equations and no an adaptive observer based approach. The researcher propose use of dynamic features of black box (Auto Regressive with eXogenous input - ARX) [5] Alessandro De Carli ,Rccardo Cirillo applied the latent faults prevision applied to a component of an automatic plant glass industry. Here a clear picture of Fuzzy logic applied using the Mamdani Method. Thought the construction of linguistic rules ,fuzzy logic gives mathematical instrument to transpose the typical nuances of person ,s reasoning and experience in a precise and strict treatment ,fuzzy logic is also particularly useful in research . [10] R.A Reese, In “Press Operations “ literature have describe the nip function and the important of nip control in paper making process. 35 [11] Venkat Venkatasubramaniam ,In Process fault detection and diagnosis :Past ,Present and Future proposed the various approaches to fault diagnosis and the challenges in this field . 36 CHAPTER 4 RESEARCH METHODOLOGY 4.0 Methodology In order to comply this research thesis, a proper step sequence have been follow to keep the research on track with the objective and progress of this project as refer in Figure 4.0 Fault detection research methodology 37 Data and parameter acquisition from the actual system Selection of Neuro Fuzzy method based on input and output Construct a Neuro Fuzzy algorithm Simulate and train the Neuro Fuzzy algorithm if required Test fault detection algorithm with actual future data Figure 4.0: Fault detection research methodology 4.1 Data and parameter acquisition from the real plant or system Here the data collected from actual plant. The data from DCS and other system such Darwin was selected to be use for research. The target data for this research was: Servo valve parameter from DCS : 1. Calculated Pressure from PLC system 2. Outlet Pressure from Servo valve in DCS 3. 4-20mA output current from servo valve to DCS 4. Flow rate from internal flow meter in side servo valve itself 5. Out let pressure direct measure after the servo valve connected Darwin system But the data of servo valve fault case available in Darwin only. This is due to DCS did not keep or record any data more that 2 days. Data from the Darwin system available since year 2000. Date and time of previous failure 38 cases been trace and recorded in database as in Figure 4.1 Record database. The previous cases date and time of have been recorded. Using Darwin system, data been trace back from the similar date and time. Here only data from Darwin which is the outlet pressure from servo valve. Other data that have collected and studied .For the normal run or good condition running data available easily from plant by daily observation or PVM (Predictive Maintenance) check list which done by technical personal in regular basis. The Darwin system measure using pressure transmitter at the out let of the servo valve as in Figure 4.2. Figure 4.1: Record database 39 DCS Darwin Monitoring System Top Roller Darwin Pressure Hydraulic pump Servo valve Pisto n Bottom Roller Hydraulic tank Figure 4.2: Darwin system 4.2 From Paper Making Manual We can understand on nip control process from point of view control process .The journal by R.A Reese, Senior Process Consultant CRS Sirrine Engineers, Inc Greenville, SC .XI PRESSING OPERATIONS explains the fundamental of nip control in papermaking, limitations to pressing ,press from aspect mechanical ,type of presses ,sheet transfer from wire to press section ,type of press arrangements ,press configuration consideration ,press clothing and press section variables . Manual, MOOG, D656 PQ Proportional Control Valve by MOOG GmbH, explain the construction of servo valve, and also the theoretical calculation of the function of servo valve and the electrical signal control of servo valve. 40 Transfer Function for MOOG Servo valves by W.J. Thayer ,December 1958 Rev .January 1965 from Technical Bulletin 103 ,MOOG INC ,Control Division ,East Aurora ,NY .In this literature ,the fundamental calculation of the control of the servo valve was reviewed. 4.3 Knowledge from Instrument Personal The maintenance personal have kept record of symptom, which can cause servo valve failure, and also the effect of servo valve to process papermaking. This data recorded by personal involve directly in troubleshooting the servo valve failure involved. 4.4 Introduction to Fuzzy Logic and Neuro fuzzy Fuzzy logic had a rapid growth in the number and variety of applications since few years .The applications range from consumer products such as cameras, camcorders, washing machines, and microwave ovens to industrial process control, medical instrumentation, decision-support systems, and portfolio selection. The meaning of fuzzy logic is needed to be understand for reasoning of fuzzy logic. Fuzzy logic has two different ways to be interpreted. In straight words, fuzzy logic is a logical system, which is an extension of multi valued logic. But in a other word, its can mean in predominant use today, fuzzy logic (FL) is almost synonymous with the theory of fuzzy sets, a theory which relates to 41 classes of objects with un accurate boundaries in which membership is a matter of degree. Here its view as, fuzzy logic in its specific meaning is a branch of FL. What is important is to identify it’s even in its specific meaning; the agenda of fuzzy logic is very different both in spirit and substance from the agendas of traditional multi valued logical systems. In the Fuzzy Logic Toolbox, fuzzy logic should be interpreted as FL, that is, fuzzy logic in its wide sense. What might be added is that the basic concept underlying FL is that of a linguistic variable, that is, a variable whose values are words rather than numbers. In effect, much of FL may be viewed as a methodology for computing with words rather than numbers. Although words are inherently less precise than numbers, their use is closer to human intuition. Furthermore, computing with words exploits the tolerance for imprecision and thereby lowers the cost of solution. Another basic concept in FL, which plays a central role in most of its applications, is that of a fuzzy if-then rule or, simply, fuzzy rule. Although rulebased systems have a long history of use in AI, what is missing in such systems is a machinery for dealing with fuzzy consequents and/or fuzzy antecedents. In fuzzy logic, this machinery is provided by what is called the calculus of fuzzy rules. A change that is visibility relates to the use of fuzzy logic in combination with neuro computing and genetic algorithms. More generally, fuzzy logic, neuro computing, and genetic algorithms may be viewed as the principal constituents of what might be called soft computing. Unlike the traditional, hard computing, soft computing is aimed at an accommodation with the pervasive imprecision of the real world. The guiding principle of soft 42 computing is: Exploit the tolerance for imprecision, uncertainty, and partial truth to achieve tractability, robustness, and low solution cost. In coming years, soft computing is likely to play an increasingly important role in the conception and design of systems who’s MIQ (Machine IQ) is much higher than that of systems designed by conventional methods. Among various combinations of methodologies in soft computing, the one that has highest visibility at this juncture is that of fuzzy logic and neuro computing, leading to so-called neuro-fuzzy systems. Within fuzzy logic, such systems play a particularly important role in the induction of rules from observations. An effective method developed by Dr. Roger Jang for this purpose is called ANFIS (Adaptive Neuro-Fuzzy Inference System). This method is an important component of the Fuzzy Logic Toolbox. Fuzzy logic is all about the relative importance of precision. All books on fuzzy logic begin with a few good quotes on this very topic, and this is no exception. Here is what some people have said in the past. Precision is not truth. —Henri Matisse Sometimes the more measurable drives out the most important. —RenéDubos Vagueness is no more to be done away with in the world of logic than friction in mechanics. —Charles Sanders Peirce I believe that nothing is unconditionally true, and hence I am opposed to every statement of positive truth and every man who makes it. —H. L. Mencken 43 So far as the laws of mathematics refer to reality, they are not certain. And so far as they are certain, they do not refer to reality. —Albert Einstein As complexity rises, precise statements lose meaning and meaningful statements lose precision. —LotfiZadeh 4.4.0 Part In This Research There 3 major parts in this research: 1. Fault Detection - Neuro - Fuzzy –Sugeno Method 2. Fault Isolation – Fuzzy Logic - Mamdani Method 3. Early Prediction – Neuro network There are 2 model need are to be constructed. There are: 1. Sugeno model - to train data and construct the model 2. Mamdani model – is the decision making model 3. Early Prediction – to detect symptoms of the change in signal 44 4.4.1 Fuzzy logic model The fault isolation is the part fault detection system will Fuzzy logic .The fuzzy logic the used to construct the Isolation model. This Isolation Model is done using Mamdani structure concept using the Mat lab. 4.4.2 The Modeling Mamdani The information from real plant will be used to construct the Rules. This rule are base on the analyze data and experience from personal. Case reported People experiences Fuzzy logic (Fuzzification) Normal run data Theoretical/Analyzed data Figure 4.3: Fuzzy logic as in Mamdani concept Output/conclusion/ Action 45 4.4.3 Neuro Fuzzy Model Using all the data collected as been in the (4.1) data and parameter acquisition from the real, model of system is to be constructed. The neuro fuzzy will be used to construct model the system .The type of fuzzy system used in this research is Takagi –Sugeno (TS) Fuzzy Model. Figure 4.4 shows the general block diagram of TS Fuzzy Model. Fuzzification Layer Inference Mechanism De Fuzzification Rule Base Figure 4.4: Block diagram of TS Fuzzy Modeling 4.4.4 The Modeling Sugeno 4.4.5 The construction of Sugeno model in Mat lab The faulty signal captured during instrument fault will be presented a numerical manner. The trend that capture by Darwin system will be converted to table form .The 3 type fault signal, signal during the electronic card fail, filter experience blockage and the O ring break will complied and the output is categories for each fault signal.1 is the output assign for the O ring breakage,2 is 46 for the filter blockage ,and 3 is for electronic card fault. Assign output can view from Table 4.5 as below Table 4.5: Output Assigned Table Faulty part in Servo Symptom in Darwin Trend Assign output valve for Modeling O ring breakage Reading fluctuate 1 Filter blockage Reading Offset 2 Electronic card fault Reading lost/lower the minimum 3 The example of actual data as below, The Example of actual data as in table 4.6, Table 4.6 Data to Mat lab Fluactutate 16.46 16.21 16.46 15.39 16.23 16.34 Reading Offset 13.87 13.87 13.87 13.87 13.87 13.87 Lost signal 13.87 13.87 13.87 13.87 13.87 13.87 Fault Type O O O O O O ring break ring break ring break ring break ring break ring break 47 Data will be load to Anfis and be trained in Mat lab. >> Anfisedit Figure 4.7: Loaded data 48 Figure 4.8: Selection of Membership function 49 Figure 4.9: Trained data 50 The model will generated by the Mat lab Figure 4.10: The generated Sugeno model 51 The membership function generated by Mat lab can be seen as below: Figure 4.11: The input membership of input 1 52 Figure 4.12: The input membership of input 2 53 Figure 4.13: The input membership of input 3 54 The output membership function is as below: Figure 4.14: The output membership model generated 55 The rules from generated model : Figure 4.15: The output model rules generated 56 The generated output model rules generated in Rules Editor Figure 4.16: The output model rules generated in Rules Editor 57 The generated Sugeno Model Structure: Figure 4.17: The generated Sugeno Model Structure 58 Figure 4.18: The generated Sugeno Model from Surface viewer The model can be tested by running the command in Editor a = readfis(‘the model name ’); Evalfis([ X Y Z ],a) Where : X - INPUT1 Y – INPUT2 Z – INPUT3 a – output model 59 Figure 4.19: The command to test the output of generated Sugeno model 60 The tested output generated in Mat Lab Command Window Figure 4.20: The tested output generated in Mat Lab Command Window 61 4.4.6 The construction of Mamdani model in Mat lab The reported case in database will be listed and analysis one by one in order to find the symptoms of fault during operation plant and trouble shooting step taken by personal. From the gathered data, Figure 4.21: Database report which will be report by personal involve in troubleshoot 62 List will be as below, Table Date 03-Nov-05 05-Dec-05 27-Dec-05 23-Nov-05 29-Mar-05 16-Feb-05 01-Feb-05 27-Jul-06 13-Jan-06 05-Jan-06 4.22: List of fault from Database report Possiblility fail Symptom Action electronic card reading fluctuate 10 bar change servo electronic card reading fluctuate 8-30 bar (sp 17.5) change servo electronic card feedback higher than setpoint change servo electronic card reading output lost change servo reading did not change according change to setpoint servo electronic card fuse blown reading from sv lost replace new fuse electronic card reading fluctuate change servo loose mounting leakage oil physical retighten mount unstable oil system reading fluctuate when ramping monitor system reading intermitterly reading high/lowcan not follow set point(unstable) change servo Compile and investigate more deep from the gather data, until the final element of servo valve which fail recognized. The investigation until the recognized fault can be correlated theoretically with failure part of servo valve . Recognized fault can investigate more deep by run the Why - Why - Why analysis in such as cases. The symptoms also can be under stand by understand the design and structure of servo valve from manual. One all the compiled the reasoning for servo valve failure can be as below in Table 4.23: List of fault from Analysis. But for this thesis research will focus on O ring, Filter and Electronic card problem as was record this type fault happen twice more of the servo valve operation life in the plant. 63 Table 4.23: List of fault from Analysis Faulty part in Servo Symptom in Darwin Trend valve O ring breakage Reading fluctuate from set point Filter blockage Reading Offset from set point Electronic card fault Reading lost/lower the minimum Construct the rules from the analysis data and concept of the servo valve application. No 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 Deviation Offset Signal Lost Electronic cardFilter negative low deviate negative low have signal ok block negative low have signal ok block normal positive high deviate negative low have signal ok block negative low deviate normal have signal ok ok normal normal have signal ok ok positive high deviate normal have signal ok ok negative low deviate positive highhave signal ok leak positive highhave signal ok leak normal positive high deviate positive highhave signal ok leak negative low deviate negative low no signal fail ok negative low no signal fail ok normal positive high deviate negative low no signal fail ok negative low deviate normal no signal fail ok normal normal no signal fail ok positive high deviate normal no signal fail ok negative low deviate positive highno signal fail ok normal positive highno signal fail ok positive high deviate positive highno signal fail ok Table 4.24 O ring broken ok broken broken ok broken broken ok broken ok ok ok ok ok ok ok ok ok Constructed rules base on knowledge of fault analysis 64 The apply written rules Mamdani as in Figure 4.31 Construction of the Mamdani model, by calling the anfisedit function in Matlab Figure 4.25: Construction of the Mamdani model 65 Figure 4.26: Membership function for set point deviate from Measure value in the Mamdani model 66 Figure 4.27: Membership function for Measure value offset set point from Mamdani model 67 Figure 4.28: Membership function for output for electronic card fault from Mamdani model 68 Figure 4.29: Membership function for output for filter blockage in Mamdani model 69 Figure 4.30: Membership function for output for o ring breakage in Mamdani model 70 Figure 4.31: Apply the constructed Rules from Figure 4.24 into the Rules Editor in Mamdani model 71 Figure 4.32: Ruler Editor generated by Mamdani model 72 Figure 4.33 : Ruler Surface generated by Mamdani model 73 4.4.7 The construction of Early Prediction model in Mat lab The prediction principle is from the AI technique neuro network. There the 6 stage early prediction concept introduced. The data will be loaded in to the Trn_ 4 program ,the MF is initialize with the epochs .The data will be trained in algorithm and the output will recognize to understand the error occur . Data captured during fault happen , will load in Mat-lab Workspace .This data will be used to training. Number of times training need depending epoch number that been training ,And the generated MF will be tested .Comparison between actual and generated MF output will be analyze .Different epoch will be tried to get the best comparison . 74 CHAPTER 5 RESULTS 75 5.0 Result of Neuro Fuzzy Figure 5.1: The output membership of Neuro Fuzzy model generated 76 The rules from generated Neuro Fuzzy model Figure 5.2: The output Neuro Fuzzy model rules generated The generated output model rules generated in Rules Editor 77 Figure 5.3: The output Neuro Fuzzy model rules generated in Rules Editor 78 The generated Neuro Fuzzy Model Structure Figure 5.4: The generated Sugeno Model Structure 79 Figure 5.5: The generated Sugeno Model from Surface viewer 80 Testing input Figure 5.6: The command to test the output of generated Sugeno model 81 Enter value for input1 = –1.46 , input 2 = 0.3 , input 3 = 0.025 Figure 5.7: Output generated by Sugeno model 82 Generated output at Mat lab [0.7231 0.5 0.1732], which is same as generated by Anfis rules output. Compared the rules developed output with tested data Figure 5.8: To check with the output generated by Sugeno model 83 5.1 Result of Mamdani Figure 5.9: Output of Sugeno model rules 84 Tested Output set point deviate =-01.46,offset_mv=0.3,Signal_lost=0.025 Electronic card = 0.723 ,filter = 0.5 , O ring = 0.17 Figure 5.10 : Output of Sugeno model rules 85 5.2 Result of Prediction Output For epoch, n = 500 , MF = 2 Figure 5.11: Comparison predicted data and actual data Blue color trend is the trend of actual data Green color trend is the predicted trend output by neuro network 86 Figure 5.12: Prediction Error of the neuro network 87 Output For epoch, n = 1000 ,MF = 2 Figure 5.13: Comparison predicted data and actual data Blue color trend is the trend of actual data Green color trend is the predicted trend output by neuro network 88 Figure 5.14 : Prediction Error of the neuro Network 89 Output For epoch, n = 1500 ,MF = 2 Figure 5.15: Comparison predicted data and actual data Blue color trend is the trend of actual data Green color trend is the predicted trend output by neuro Network 90 Figure 5.16: Prediction Error of the Neuro Network 91 Output For epoch, n = 2000 ,MF = 2 Figure 5.17: Comparison predicted data and actual data Blue color trend is the trend of actual data . Green color trend is the predicted trend output by neuro Network. 92 Figure 5.18: Prediction Error of the neuro Network 93 Output For epoch, n = 3000 ,MF = 2 Figure 5.19:Comparison predicted data and actual data Blue color trend is the trend of actual data Green color trend is the predicted trend output by neuro Network 94 Figure 5.20: Prediction Error of the neuro Network 95 5.3 Analysis 5.3.1 Fuzzy Logic The knowledge that been understand from the fault sign have been use to construct a fuzzy logic with concept of Mamdani. The decision making of this Mamdani model very much relies on the knowledge of human. The collected data from Data base system fine input for the fuzzy logic modeling. The data shows a clear picture of the fault occur. From the data, study and analysis need to be done in detail in order to get the fine level of information which need to be used for modeling the fuzzy logic. Once the construction model have been made, the next level is to verify the parameter setting in fuzzy logic. This can be only done with the knowledge of the people who know the behavior of the system will. The simulation need to be done to verify the outcome of constructed model. As can be seen , during simulation input set on the Ruler Editor and also in the in command program where the function readfis( ) and evalfis () use to check the output of model constructed. The example as in the Result of Mamdani page: The entered input :Output set point deviate =- 01.46,offset_mv=0.3,Signal_lost=0.025.And output produced is : Electronic card = 0.723 ,filter = 0.5 , O ring = 0.17 96 5.3.2 Neuro Fuzzy The Neuro Fuzzy ,is constructed by using the captured numerical data during fault occur in the system. The Neuro Fuzzy is based on Sugeno method .The Neuro Fuzzy is used to construct model that can recognized the fault occur from signal input. In order to do that, the data need to be train on Sugeno model. The step as in the previous chapter in the designing the Sugeno Model. The parameter to be set during modeling the Neuro Fuzzy such as Number Of Member function is depend the type of the system to be construct. The Neuro Fuzzy trained and the structure will be tested as in the Testing of Sugeno model. The simulation is to confirm the outcome of the system. There are single which was define by range as recognized output as 1 –o ring broken ,2 –filter damage and 3 –electronic card fail. This output will define the type of failure from the data from plant. 5.3.3 Neuro Network The prediction system is using the concept of neuro network. The data need to be feed in to train the neuro network system. This system is used to detect an early sign of error occur from the input data. The system is capable of predicting the future data that will be produced. From the output simulation, the Prediction Error , its start to show the error is getting higher before the actual large variation happen in the shorter time later. This technique help to detect before the instrument totally fail from its function. 97 CHAPTER 6 CONCLUSION 98 6.0 What have been done during this research During this research, there are many thing have been carry out. The first step to do is studies on the behavior of instruments in plant and the type of fault occur in instrument. The instruments need to know by its structure and application of it in area of studied. Understand the process and how instrument affecting the process. The available data of fault is very important in order to select proper tool for the case studies .The selection of type of data will also lead the analyze type to be carry out. From the available type of data, its will be gather and analyze .The analyzing process require more time due some of the information will be mixed by fact and some information will be need to interpreted back with some assumption. The construction of AI technique for this research channel by the literature study . The have been a lot of literature study which have been carry out in order to get the correct path of the AI technique guide line .The selected AI technique in this research will be Neuro Fuzzy, Fuzzy logic and Neuro Network according to the application of each of this technique. The selected AI technique will be constructed in Mat – Lab software. During simulation some adjust may need to be done and some debugging might be required .The adjust will be done on some of the parameter until the require output is obtain . Once the fine tuning done, the model that have been constructed will be tested again using the data from real plant again to verify the out come. 99 6.1 What have been gains from this research There are a lot of thing gain and learn during this case studies conducted .The basic of what have been done in the case study as how raw data from real plant need to be extracted and how to convert it into useful information in order to run the AI technique .Here the application of Artificial Intelligent such as the Neuro Fuzzy ,Fuzzy Logic and Neuro Network have been experience using the actual data from the real plant. The under stand of technique of Artificial Intelligent in term of conceptual ,application and practical application. But there are some knowledge learn indirectly from this case study . The methodology from other field which can proposed in another field. Where AI is the field of Computer Science study technique applied in Instrumentation and Engineering to run the research on fault detection. The out of box concept where new type of suggests can be taken in to consideration. Analyzing data many not to be as straight and easy. Sometime might need to look from other point and different kind of interpretation. Any more data can be extracted from it. Focusing on the problem occur and find the solution may not only from the existing data resource but also by understanding the basic concept of problem and applying a good tool. 101 6.2 Recommendation 1.The other system that can be use in this research is System Identification Tool box in Mat lab to construct the model of the symptoms. Using the capture fault signal a fault model can also be constructed . 2.A model of servo valve can be constructed by using the transfer function of servo valve which available in [22] Transfer Function for MOOG Servo valves by W.J. Thayer, December 1958 Rev. January 1965. Using the theoretically calculated system fault model, the output of system can be determined. But this two comparison might have difference .In actual plan the reading might oscillate within a tolerance range and the calculated output model might view as very accurate and constant reading. The acceptable tolerance range for oscillating reading is depend on the servo valve itself .The other this the tool that used to measure the error signal might need . 3. The system can be up grade for the universal fault detection system for all type of instrument. Most instrument use 4 -20 mA .A lot of monitoring device available in market to capture this signal. Algorithm can be made to use an general signal 4 – 20 mA to detect and recognized fault occurrences in instrument. Other that the algorithm ,using other technique AI to detect the early failure as Neuro Network in servo valve application. 5. More additional features tool and features can be added in the fault system in order to increase reliability and efficiency of the system develop. 102 6.3 Reference literature [1]Rolf Isermann and Mihaela Ulteru ,”Integrated Fault Detection and Diagnosis” Technical University of Darmatdt Institute of Automatic Control Laboratory for Control Engineering and Process Automation . [2]Rolf Isermann ,”Model Based Fault Detection and Diagnosis Method” Technical University of Darmatdt , Institute of Automatic Control Laboratory for Control Engineering and Process Automation . 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