Fault Tolerant Computer for the AUTOMATED TRANSFER VEHICLE

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

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

3. 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 Current Fault Tolerant Techniques

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

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

6. Various capacities of ATV Current Fault Tolerant Techniques

7. ATV Constraints • Tolerance to hardware faults • Tolerance to software faults • Safety concept 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) Current Fault Tolerant Techniques

9. Vital/Nominal breakdown 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. Current Fault Tolerant Techniques

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

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

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

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

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

17. FTC channel architecture 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 Current Fault Tolerant Techniques

19. References • R.Roques,A.Correge,C.Boleat - Fault Tolerant Computer for the Automated Transfer Vehicle • http://www.esa.int/SPECIALS/ATV/index.html • http://en.wikipedia.org/wiki/Automated_Transfer_Vehicle Current Fault Tolerant Techniques

20. References Contd. Current Fault Tolerant Techniques

21. Questions??? Current Fault Tolerant Techniques