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

2. 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

3. 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

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

5. 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

6. 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

7. 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

8. 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

9. 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

10. 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

11. 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

12. 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

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

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

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

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

17. 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

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

19. 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

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

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

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

23. 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