Method and device for consolidation by software synchronisation in flight control computers

• US 7,890,221 B2
• Filed: 05/07/2007
• Issued: 02/15/2011
• Est. Priority Date: 05/19/2006
• Status: Expired due to Fees

• Current Assignee: Airbus Operations SAS (Airbus SE)
• Original Assignee: Airbus France
• Inventors: Kossentini, Chiheb
• Primary Examiner(s): Beaulieu; Yonel
• Application Number:
  US11/745,149
• Publication Number:
  US 20070271010A1
• Time in Patent Office: 1,380 Days
• Field of Search: 701/3, 701/14, 701/1, 340/945, 375/354, 375/356, 377/64, 377/66
• US Class Current: 701/1
• CPC Class Codes: G06F 11/1637 using additional compare functionality in one or some but not all of the redundant processing components
• CPC Class Codes: G06F 11/1675 Temporal synchronisation or re-synchronisation of redundant processing components
• CPC Class Codes: G06F 11/188 where exact match is not required

Abstract

A method for synchronising two asynchronous control and monitoring units of a computer, wherein each of these units comprises a computation unit. The method includes a computation of independent local Boolean signals, each having a Boolean inertia greater than the temporal uncertainties, due to the latencies in transmission between computers and the precision of the sampling controlled by the clock cycle of each unit, capable of affecting them. The method also includes an exchange, between the two units, of local signals, with each unit sending a locally computed value to the other unit, the generation of a pair of synchronised signals, in each unit, based on the local value and the value received from the other unit, and the formation of a consolidated signal based on the pair of synchronised signals.

Claims

1. A method for synchronising two asynchronous COM and MON units, for control and monitoring, respectively, of a computer of a computation system comprising a plurality of computers connected to one another by a communication connection, wherein each of the COM and MON units comprises a computation unit, the method comprising:

computing independent local Boolean signals, each having a Boolean inertia greater than temporal uncertainties, due to latencies in transmission between computers and precision of a sampling controlled by a clock cycle of each of the COM and MON units, capable of affecting them,

exchanging, between the COM and MON units, of local signals, with each of the COM and MON units sending a locally computed value to the other unit,

generating a pair of synchronised signals, in each of the COM and MON units, based on its locally computed value and the computed value received from the other unit,

forming a consolidated signal based on the pair of synchronised signals.

2. The method according to claim 1, the local signals being computed by different algorithms based on different sensors, or a result from logics associated with sensors.

3. The method according to claim 1, the local signals each having a Boolean inertia greater than twice a non-deterministic delay capable of affecting them.

4. The method according to claim 1, the connection between the two asynchronous units being provided by an inter-unit bus and/or by a cable-type connection.

5. The method according to claim 1, the communication connection between the computers comprising at least one inter-unit bus and/or at least one cable-type connection.

6. The method according to claim 1, implementing a robust refresh method.

7. The method according to claim 6, each of the COM and MON units:

detecting a change in value of an input among the actual Boolean signal of said unit and the signal received from the other unit,

maintaining an internal counter in the unit,

retaining a certain stable value,

refreshing this value on a given condition.

8. The method according to claim 1, each of the COM and MON units being designated by i and implementing a counter ni, initially at an initial state ni=0, and such that, if the unit i sees one of its own inputs change, and no inputs of the other units change, it distributes the change of its input by refreshing its output to one of the other units and positions its counter at third state ni=3.

9. The method according to claim 8, the counter being such that, if ni=0, and if the unit i sees changes in inputs of the other units, it distributes the change of its input by refreshing its output to one of the other units and positions its counter in a second state ni=2.

10. The method according to claim 8, in which, in each step, each unit i decrements its counter, down to the initial state ni=0.

11. The method according to claim 9, in which, in each step, each unit i decrements its counter, down to the initial state ni=0.

12. The method according to claim 10, in which, when ni=1, each unit i executes the refresh operation of its local pair of signals synchronised by a pair of refreshed values.

13. The method according to claim 11, in which, when ni=1, each unit i executes the refresh operation of its local pair of signals synchronised by a pair of refreshed values.

14. The method according to claim 1, the plurality of computers belonging to an electric flight control system.

27. An aircraft comprising a device capable of implementing the method according to claim 1.

15. A computation system comprising a plurality of computers connected to one another by a communication connection wherein at least one of the computers is asynchronous and comprises at least two asynchronous COM, MON units, for control and monitoring, respectively, each of these units comprising a computation unit as well as:

a computing unit configured to compute independent local Boolean signals, each having a Boolean inertia greater than temporal uncertainties capable of affecting them,

an exchanging unit configured to exchange between the two units COM and MON, local signals, wherein each unit sends a locally calculated value to the other unit,

at least one generator of a pair of synchronised signals, in each of the COM and MON units, based on its locally computed value and the computed value received from the other unit, and

a forming unit configured to form a consolidated signal based on the pair of synchronised signals.

16. The system according to claim 15, the communication connection between the two computation systems comprising at least one inter-unit bus and/or one cable-type connection.

17. The system according to claim 15, a communication connection between the COM and MON units comprising at least one inter-unit bus and/or one cable-type connection.

18. The system according to claim 15, implementing a robust refresh method.

19. The system according to claim 18, further comprising:

a detection unit configured to detect a change in value of an input;

a maintaining unit configured to maintain an internal counter of the unit;

a retaining unit configured to retain a certain stable value, and

a refreshing unit configured to refresh this value on a given condition.

20. The system according to claim 15, each of the COM and MON units being designated by i and comprising a counter ni, initially at an initial state ni=0, and being configured so that, if this unit i sees one of its own inputs change, and no inputs of other units change, it distributes the change of its input by refreshing its output to one of the other units and positions its counter at a third state ni=3.

21. The system according to claim 20, the counter being configured so that, if ni=0, and if the unit i sees changes of inputs of the other units, it distributes the change of its input by refreshing its output to one of the other units and positions its counter at a second state ni=2.

22. The system according to claim 20, in which, in each step, each unit i decrements its counter, down to 0.

23. The system according to claim 21, in which, in each step, each unit i decrements its counter, down to 0.

24. The system according to claim 22, being configured so that, when ni=1, each unit i executes the refresh operation of its local pair by a pair of refreshed values.

25. The system according to claim 23, being configured so that, when ni=1, each unit i executes the refresh operation of its local pair by a pair of refreshed values.

26. The system according to claim 20, the computer belonging to an electric flight control system.

28. An aircraft comprising the system according to claim 15.