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5.2 Scope of the Target System Diagnosing the Beam Propeller Movement of the Frontal Stand Figure 5.2: Beam Propeller Movement of the frontal stand Field Contents DefectNr 63000011 Description Application error: Error on Junction Movement Type Error Unit Geometry Info Count 1 Mode - Time 17:38:16 [FREE TEXT] Time of occurrence : 2005-10-24. 17:37:56 [SEVERITY] Error [EXCEPTION DESCRIPTION] Error report Junction movement. Imin : -8462 mA Imax : 64 mA Iact : -214 mA Iset : -8724 mA Vact : -21 au/s Vset : -41 au/s Pact : -109 au Pset : -107 au State : MotorisedMoving Note : au = 0.1deg. or mm Error(s) found : current error Table 5.1: Example of a log entry (when error 11 occurs). error detection mechanism detects an error, appropriate recovery action are invoked, and an error is logged. The following section describes the error that is logged by the error detection mechanism. 5.2.2 The Error of the Beam Propeller Movement The error that is logged by the error detection mechanism contains information about the state of the system, at the moment the failure occurred. The target system only includes those components that this state refers to. Table 5.1 shows an example of the error message. Such a message is logged each time one of the Geometry’s mechanical movements malfunctions. Among the Geometry developers it is known as error 11. A log entry typically contains diagnostic information about a part of the system. In this case, an occurrence of error 11 pinpoints to a failure of one of the mechanical movements within the Geometry subsystem. The field Description of Table 5.1 indicates what movement’s error detection mechanism has detected the error: the beam propeller movement of the frontal stand. In addition to that, it would help if the error message contains information about the system’s state at the time the error occurred. In this case were are quite lucky: there is a Exception Description 52
Diagnosing the Beam Propeller Movement of the Frontal Stand 5.2 Scope of the Target System part in the row Info that enumerates all kinds of parameters. These parameters all say something about the state of the system. The scope of the target system depends on considerations, that are specific for PMS, this particular subsystem, and motives of the modeler. Not all components that could cause a failure of the beam propeller movement are included in the target system. The architecture of the system that contains components that are considered is described in Appendix B.1. The considerations to decide if components are included or excluded in the target system are as follows. For all known components the following questions are asked: 1. Could a PMS service engineer replace this component with a healthy one? In other words, is the component a FRU? 2. Does the malfunctioning of this components causes an error 11 message to be logged? 3. Could an expert think of any (hypothetically) produced error 11 log data, of which any conclusions about the component’s state could be derived? 4. Does including the component lead to superfluous complexity of the model? 5. Is the component part of a control loop? If, for a certain component, all answers on these questions are positive, the component is included in the scope of the target system. The last consideration is special to this specific subsystem. The beam propeller movement is implemented by means of three nested control loops, respectively a position loop, speed loop, and current loop. These three control loops play an important role, and therefore this question is of importance (see Section 5.3). Table 5.2 shows the components that are excluded (see Appendix B.1 for the place of a component within the architecture). The discussed fault diagnosis only addresses the components that are Component Failing Consideration All components that propagate or influence (the cloud in Figure 5.2) the requests 2 speed signal until it enters the backpanel control unit. backpanel control unit 3 LUC 3 Power Supply 4 Table 5.2: Components that are excluded from the target system. part of the subsystem Geometry. All components of other subsystems that might lead to a failure of the beam propeller movement do not cause an error 11 message to be logged. The backpanel control unit and the LUC are not included. The reason for this is that in the current technical setup it is impossible to differentiate if faults are activated by the backpanel control unit, LUC or its corresponding LUC_Extension. Because the LUC_Extension has, by far, the highest a priori failure probability, it has been chosen to include this component in the target system. The power supply is not included, because adding it leads to superfluous complexity of the model. Note that the fault diagnosis process proposed below could be extended to enable the diagnosis of these, currently, omitted FRUs as well. Table 5.3 names the set of components that are within the scope of the diagnostic process. Each of them has been given an a priori component failure. These values only determine the order of 53
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Automated Fault Diagnosis at Philip
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© 2006 W.M. Lindhoud. Document gen
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Preface The work presented in this
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CONTENTS 4.4 Modeling . . . . . . .
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List of Tables 3.1 Evaluation appro
Page 16 and 17: 1.1 Fault Diagnosis Introduction Fi
Page 18 and 19: 1.2 Automated Fault Diagnosis Intro
Page 20 and 21: 1.5 Outline of the Thesis Introduct
Page 23 and 24: Chapter 2 State-of-the-Practice Fau
Page 25 and 26: State-of-the-Practice Fault diagnos
Page 33 and 34: Chapter 3 Automated Fault Diagnosis
Page 35 and 36: Automated Fault Diagnosis 3.1 Overv
Page 41 and 42: Automated Fault Diagnosis 3.3 Off-l
Page 43 and 44: Automated Fault Diagnosis 3.5 Model
Page 45: Automated Fault Diagnosis 3.6 Evalu
Page 48 and 49: 4.1 Fundamentals Model-Based Fault
Page 50 and 51: 4.2 Model-Based Diagnosis with LYDI
Page 52 and 53: 4.3 Basic Assumptions Model-Based F
Page 54 and 55: 4.4 Modeling Model-Based Fault Diag
Page 56 and 57: 4.4 Modeling Model-Based Fault Diag
Page 58 and 59: 4.5 Entropy Gain Model-Based Fault
Page 60 and 61: 4.6 MBD on the Power Supply Model-B
Page 63 and 64: Chapter 5 Diagnosing the Beam Prope
Page 65: Diagnosing the Beam Propeller Movem
Page 69 and 70: Diagnosing the Beam Propeller Movem
Page 83 and 84: Chapter 6 Conclusions and Recommend
Page 85: Conclusions and Recommendations 6.2
Page 88 and 89: BIBLIOGRAPHY [12] Johan de Kleer an
Page 91 and 92: Appendix A Glossary of terms In thi
Page 93 and 94: Glossary of terms • Diagnostic Pe
Page 95 and 96: Glossary of terms • Model: an abs
Page 97: Glossary of terms • System: an en
Page 100 and 101: B.2 System Data Case Study Details
Page 102 and 103: B.4 Full List of Examined Fault Sce
Page 104 and 105: B.5 Discretization of Implementatio
Page 106 and 107: C.1 The Synthetic Models that are U
Page 108 and 109: C.2 Model of the Power Supply Examp
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C.3 The Models Constructed for the
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Appendix D State-of-the-Future Faul
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