1. Fault Tolerant Computer for the AUTOMATED TRANSFER VEHICLE
Chandan Kumar
EE 585: Fault Tolerant Computing

2. Current Fault Tolerant Techniques
Outline
Background of ATV
ATV Contraints
Fault Tolerant Computer
Fault Tolerance Implementation
FTC development model
Conclusion and perspectives
EE 585
Current Fault Tolerant Techniques

3. Current Fault Tolerant Techniques
Background of ATV
Automated Transfer Vehicle-a servicing vehicle for the ISS
1st ATV(Jules Verne)
Being developed by ESA
To be launched aboard Ariane 5 by late 2007
EE 585
Current Fault Tolerant Techniques

4. Current Fault Tolerant Techniques
Functions of ATV
Deliver fuel and logistics
General supplies
Water and oxygen
Conduct experiments
Conduct orbit adjustment
Serves as a waste collector
EE 585
Current Fault Tolerant Techniques

5. Current Fault Tolerant Techniques
On orbit life of 180 days
Expendable burns up upon re-entry
EE 585
Current Fault Tolerant Techniques

6. Various capacities of ATV
AUTOMATED TRANSFER VEHICLE (late 1997 baseline)
Dry cargo (max.11.2m3 in 8 racks plus 4m3 in center aisle)
1102
kg (5500 kg max.)
Maximum refuel for Russian Service Module
860 kg
Maximum H2O for Russian Service Module
840
Maximum N2, O2 for Russian Service Module
100
Max. propellant available for reboost
4080
Rendezvous & docking propellant (400N thrust,310s Isp)
2680
Cargo Carrier (CC)
4011
Optional CC refueling,water,gas transfer equipment
1246
ATV Dry mass (including system margin)
5581
20500
kg maximum launch wt.
EE 585
Current Fault Tolerant Techniques

7. Current Fault Tolerant Techniques
ATV Constraints
Tolerance to hardware faults
Tolerance to software faults
Safety concept
EE 585
Current Fault Tolerant Techniques

8. Fault Tolerant Computer
Developed by Matra Marconi Space
Resides in the avionics module
Triple FTC and MSU(Monitoring and Safing Unit)
EE 585
Current Fault Tolerant Techniques

9. Vital/Nominal breakdown
EE 585
Current Fault Tolerant Techniques

10. Fault detection and the subsequent action
Upon detection of a critical failure or an unsafe situation,
The Monitoring and Safing Unit (MSU) isolates the ATV’s nominal system and commands a Collision Avoidance Manoeuvre (CAM).
This brings the ATV on a safe trajectory within the monitoring corridor towards the ISS.
Once the Collision Avoidance Manoeuvre is completed, the MSU points the vehicle towards the Sun, thus ensuring sufficient power from the solar panels during the ‘survival’ mode that the vehicle enters.
EE 585
Current Fault Tolerant Techniques

11. Allocation of S/W entities
EE 585
Current Fault Tolerant Techniques

12. Fault Tolerance Implementation
Characterised with respect to
Fault containment layers and sub layers
Inter-channel synchronisation
Time determinism
Fault passivation and reconfiguration
EE 585
Current Fault Tolerant Techniques

13. Fault Containment approach
Nominal/Vital segregation
Intra-vital segregation
EE 585
Current Fault Tolerant Techniques

14. Current Fault Tolerant Techniques
Inter-channel synchronisation approach
Time determinism
EE 585
Current Fault Tolerant Techniques

15. Current Fault Tolerant Techniques
Fault reconfiguration approach
Channel passivation after failure
Application passivation after software failure
Hardware/software allocation
EE 585
Current Fault Tolerant Techniques

16. Current Fault Tolerant Techniques
FTC development model
FTC hardware implementation
Computer internal design
Inter-computer link design
EE 585
Current Fault Tolerant Techniques

17. FTC channel architecture
EE 585
Current Fault Tolerant Techniques

18. Conclusion and perspectives
New generation fault tolerant computer-combines high perfomance,compact/low cost design and tolerance to application software faults.
Integrating software fault tolerance is a significant cost saving factor.
Technically mature product.Fully suitable to ATV
Open architecture and performance margins make it adaptable to the needs of future reusable launch vehicles
EE 585
Current Fault Tolerant Techniques

19. Current Fault Tolerant Techniques
References
R.Roques,A.Correge,C.Boleat - Fault Tolerant Computer for the Automated Transfer Vehicle
EE 585
Current Fault Tolerant Techniques

20. Current Fault Tolerant Techniques
References Contd.
EE 585
Current Fault Tolerant Techniques

21. Current Fault Tolerant Techniques
Questions???
EE 585
Current Fault Tolerant Techniques