Kumar119/ MAPLD 20041 A GENERIC COMPONENT BASED EXPERT SYSTEM SHELL FOR AIRBORNE EQUIPMENT DESIGN...

Kumar 119/ MAPLD 2004 1

A GENERIC COMPONENT BASED EXPERT SYSTEM SHELL FOR AIRBORNE EQUIPMENT DESIGN

B.Ramesh Kumar1, J.Shanmugam1, S.Janarthanan2 & R.Santhiseela2

1 Madras Institute of Technology, India2 Defence R&D Organisation, India


ObjectiveExpert System for GAS

• Expert System to provide Guidelines• Architecture Selection• Environmental Testing• EMI/EMC• Reliability Engineering• Testability• Power

• Expert System for Auditing - To Provide Testing Procedure for the equipment & component and help the designer with the evaluation process

• Expert System for Searching


Why such a System is needed?

Problem 1: Interlinking of various domains• The design of airborne equipment requires expertise knowledge in various

interdependent domains• Thus the simultaneous processing of all domains make the design complex

• If the airborne equipment is going to be critical in its function, then the design becomes more complex

• All these burdens the designer

Problem 2 : Voluminous of Parameters• In the design of airborne equipment lots of parameters have to be considered

in detail• Due to voluminous of data and parameter, the designer can leave some

parameters unnoticed or may skip one or more design steps


Expert System

• The British Computer Society’s specialist group on Expert System produced the following formal definition: “An Expert System is regarded as the embodiment within a computer of a knowledge-based component, from an expert skill, in such a form that the system can offer intelligent advice or decision about a processing function”

ACQUISITION

QUERIES +EXPLANATION

KNOWLEDGEBASE

INFERENCE ENGINE

HUMAN EXPERT

USER

KNOWLEDGE ENGINEERING


How KNOWLEDGE BASE for Airborne Equipment Design is Framed?

Block_Name

Value_1

Value_2

…

…

…

Value_n

End

Architecture_Candidate

Processor

Buses

Topology

End

Processor

Type_Of_Processor

Speed

Throughput

Weight

End

Generalised Example


How INFERENCE ENGINE in Airborne Equipment Design Expert System Works?

Buses

Bus_Width

Bus_Speed

Transmission

End

Architecture_Candidate

Processor

Buses

Topology

End

Processor

Type_Of_Processor

Speed

Throughput

Weight

End

Using Forward Chaining Method


Generic Components Based Expert System Shell

Generic Inference

Engine

Knowledge Base 1

Knowledge Base 2

Knowledge Base 3

Knowledge Base n

User Interface

.

.

.


Architecture Selection Process

• Frame Standard Metrics

• Determine Physical Constraints

• Select Architecture Candidates appropriately

Architecture Candidates

• Computation Element

• Communication Element

• Configuration


User Interface ArchitectureGuidelines


User InterfaceReliability Engg.


User InterfaceEnvironmental Testing


User InterfaceTestability DesignGuidelines


Testability

• Design Guidelines• Evaluation of Equipment

• Equipment = Digital Circuits + Analog Circuits + PSU + RF

• Evaluation of Digital Circuits


User InterfaceTestability Evaluation of Airborne Equipment


Testability Evaluation of EquipmentSome areas in Design & some sample Questions

Design Areas Sample QuestionsWeight (0 Weight 10)

Expert 1 Expert 2 Expert 3

Mechanical Design

Is a standard grid layout used on boards to facilitate identification of components?

Is enough spacing provided between components to allow for clips and test probes?

3

6

6

8

4

5

Partitioning

Is each function to be tested placed wholly upon one board?

If more than one function is placed on a board, can each be tested independently?

7.5

8

6

7

8

9

Parts Selection

Is the number of different part types the minimum possible?

Have parts been selected which are well characterised in terms of failure modes?

9

8.5

8

9

8.5

8

Analog Design

Is one test point per discrete active stage brought out to the connector?

Is each test point adequately buffered or isolated from the main signal path?

8.2

8.5

7

8

4

9

Digital Design

Does the design contain only synchronous logic?

Are all clocks of differing phases and frequencies derived from a single master clock?

7.8

8

NA

NA

9

8


Testability Evaluation of EquipmentStatistical Analysis

• Some Experts’ expertise in particular field like Analog, Digital, PSU etc.,

• So more Weightage is given to the score, given by the Expert of that particular field

AnalogExpert

AnalogDesign

DigitalDesign

PSU

BIT

More Weightage


Testability Evaluation of Digital Circuits

• Testability, TY = f (Controllability,Observability)

• Testability Measures - studied– SCOAP (Sandia Controllability Observability Analysis Program)

– TMEAS (Testability MEASurement program)

– CAMLOT (Computer-Aided Measure for LOgic Testability)

• CAMLOT was chosen


Testability Evaluation of Digital Circuits ATPG - Modified FAN (FANout algorithm)

• Propagate the fault to Primary Output (PO)

• Backtrace from PO to all Primary Inputs (PIs)

• Proceed with forward tracing from PIs to all Pos

• ATPG Algorithms analysed– D-Algorithm

– PODEM

– FAN

• FAN Algorithm is chosen, and modified to suit our need


Testability Evaluation of Digital Circuits Working of Modified FAN Algorithm

A

B

CY

A

B

CY

A

B

CY

A

B

CY

Y

A

B

CX

1. Fixing fault

2. Making Line to be fault

3. Propagate the fault to (PO

4. Backtrace PO value to PI

5. Find all Line values (Test patterns)


User InterfaceTestability Evaluation


Electromagnetic Interference/ Compatibility(Applicable to Airborne Equipments Excluding RF)


User InterfaceElectromagnetic Interference/ Compatibility


User InterfaceEMI/ EMC Evaluation

1 2

3


User InterfaceElectric PowerGuidelines


User InterfaceExpert System Based Guidelines Search

1. Enter the Question

2. On search, identifies the keywords and searches for them

3. It displays the matches found

4. It asks the user to select the preferred match

5. It displays the guidelines for the selected match


Organisation of Knowledge Base for Expert SearchRule Structure

Blockname

Predecessor

end

Example

B1

B0.1

end

B1.1

B1

end

B1.3

B1

end

B1.3.1

B1.3

end

How Inference Engine Works Here?

Searching for B1.3.1(end branch of a tree) leads to the identification of B1.3 which in turn identifies B1. Similarly the iteration continues till it finds the root (B0.1)


Who can use this System?

• Fresh Designer (as Study Material and as thumb rules for design)

• Designer (during Design process)• Designer (after Design is complete for Evaluation)


References

[1] Dutta.S, 1997, Strategies For Implementing Knowledge Based Systems, 20132, IEEE Trans. Engineering Management, pp. 79-90.

[2] Santhiseela.R and Janarthanan.S, 2003, An Expert System For Automatic Fault Diagnosis Of A Quadruplex Digital Computer, International Conf on Advances in Aerospace Science, pp. 294-301.

[3] Spitzer.R.Cary, 1993, Digital Avionics Systems: Principles And Practices, Ed 2, MGH Inc.

[4] James.P.Ignizio, 1991, Introduction To Expert Systems – The Development And Implementation Of Rule Based Expert System, NY, MGH Inc.

[5] Spitzer.R.Cary, 2001, The Avionics Handbook, NY, CRC Press.[6] Donald.A.Waterman, 1985, A Guide To Expert Systems, MA, Addison-Wesley Pubs Co.[7] James.N.Siddall, 1990, Expert System For Engineers, NY, Marcel Dekker Inc.[8] Dickman.T.J and Roberts.T.M, 1988, Modular Avionics System Architecture Decision

Support System, IEEE 88CH2596-5, Proc. IEEE 1988 NAECON, pp.1549-1552.[9] MIL-HDBK-338B, 1998, Electronic Reliability Design Handbook, USA, DOD.


References

[10] MIL-STD-810F, 2000, Test Method For Environmental Engineering Considerations And Laboratory Tests, USA, DOD.

[11] MIL-STD-461D, 1993, Requirements For The Control Of Electromagnetic Interference Emission And Susceptibility, USA, DOD.

[12] MIL-HDBK-1857, 1998, Grounding Bonding and Shielding Design Practices, USA, DOD.

[13] MIL-STD-2165, 1985, Testability Program For Electronic Systems And Equipment, USA, DOD.

[14] Kovijanic.P.G, 1979, Testability Analysis, IEEE Test Conference, Digest Of Papers, pp.310-316.

[15] MIL-STD-704E, 1991, Aircraft Electric Power Characteristics, USA, DOD.[16] Bennetts.R.G, Maunder.C.M and Robinson.G.D, 1981, CAMLOT: A Computer Aided

Measure Of Logic Testability, Vol. 2, Proc. IEEE International Conference On Circuit and Computers.

[17] Fujiwara.H and Shimono.T, 1983, On The Acceleration Of Test Generation Algorithms, Vol. C-32, IEEE Trans. Computers, pp. 1137-1144.

Kumar119/ MAPLD 20041 A GENERIC COMPONENT BASED EXPERT SYSTEM SHELL FOR AIRBORNE EQUIPMENT DESIGN...

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