Fault Tolerant [I/o] Networks Applied to ship control EE 585: Fault tolerant systems RAGHU SUNDEEP T

EE 585:Fault tolerant systems Abstract How the use of data buses, intelligent sensors can be used to construct (i/o) N/w that provides flexibility. I/o N/w make use of fault tolerant and damage systems Examines technology trade-offs Network media Network topology Raghu Sundeep T EE 585:Fault tolerant systems

EE 585:Fault tolerant systems Introduction Basic approach Use of Fault tolerant digital controllers with sophisticated software. Use of data multiplexing & electronics in intelligent sensors & actuators Raghu Sundeep T EE 585:Fault tolerant systems

Difference b/w Basic & Modern system Raghu Sundeep T EE 585:Fault tolerant systems

Dependability required What degree of dependability is needed? Fault modes considered in system design: Loss of Function while operating Premature operation Failure to operate at the proper time False alarms Raghu Sundeep T EE 585:Fault tolerant systems

Categories of Function Critical  endangers crew Essential  requires immediate action to prevent endanger Non-essential  No direct effect on safety of ship Raghu Sundeep T EE 585:Fault tolerant systems

Triple Modular Redundancy Only type suitable for critical functions Depends on 3 channels Operates on 2 out of 3 consensus of channels Raghu Sundeep T EE 585:Fault tolerant systems

Network i/o design trade-offs Network media selection Powering i/o network electronics Network topology Network data rate requirements Centralized or distributed i/o processing I/O channel cross taping Raghu Sundeep T EE 585:Fault tolerant systems

Network media selection Optical fiber: Advantages Supports high data rates Insensitive to electromagnetic interference Does not propagate electrical faults Optical fiber: Disadvantages Signal is attenuated by connectors Requires complex terminals Raghu Sundeep T EE 585:Fault tolerant systems

Network media selection (contd..) Wire : Advantages Small, low cost terminals are available Can deliver power in addition to data Connections are easy Wire : Disadvantages Limited speed Requires sheilding Raghu Sundeep T EE 585:Fault tolerant systems

Network media selection (contd..) Wireless : Advantages Very low cost to install Small low cost electronics needed Wireless : Disadvantages Battery should be replaced Limited bandwidth Vulnerable to EMI Raghu Sundeep T EE 585:Fault tolerant systems

Powering the I/O electronics Tap into ship’s power nearest source Distribute power as part of network Using batteries or other wireless sources Raghu Sundeep T EE 585:Fault tolerant systems

EE 585:Fault tolerant systems Network topology Ring topology Bus topology Raghu Sundeep T EE 585:Fault tolerant systems

Network topology (contd..) Raghu Sundeep T EE 585:Fault tolerant systems

Network topology (contd..) Raghu Sundeep T EE 585:Fault tolerant systems

Network topology (contd..) Raghu Sundeep T EE 585:Fault tolerant systems

I/O networks- cross connecting data between channels System without cross connection + No faults propagate b/w channels - Many two fault conditions fail system System with cross connections + System can be made fault tolerant of most two-failure conditions + Adjacent channels monitor and provides options for distributed I/O processing - Requires isolation Raghu Sundeep T EE 585:Fault tolerant systems

EE 585:Fault tolerant systems Raghu Sundeep T EE 585:Fault tolerant systems

Conclusion:- Concept for a fault tolerant network i/o system Support critical functions Primary network media : copper wire Network topology: buses Power supply: dedicated wiring as part of I/O network Cross-strap individual sensors & actuation terminals is provided Raghu Sundeep T EE 585:Fault tolerant systems

Conclusion:- Concept for a fault tolerant network i/o system Raghu Sundeep T EE 585:Fault tolerant systems

EE 585:Fault tolerant systems Applications THE VIRGINIA CLASS Raghu Sundeep T EE 585:Fault tolerant systems

EE 585:Fault tolerant systems Applications SEA WOLF SUBMARINE Raghu Sundeep T EE 585:Fault tolerant systems

EE 585:Fault tolerant systems REFERENCES “Fault-tolerant I/o networks Applied to ship control” by Robert C. Hammett Hammett, r “Seawolf ship control performance and monitoring provides fault tolerance and simplified maintenance” “Advanced integrated control and information systems in the U.S. Navy,” control system symposium. Raghu Sundeep T EE 585:Fault tolerant systems