Diagnostic system for complex systems using virtual components

• US 5,552,984 A
• Filed: 09/16/1993
• Issued: 09/03/1996
• Est. Priority Date: 09/16/1993
• Status: Expired due to Term

• Current Assignee: Northrop Grumman Systems Corporation (Northrop Grumman Corporation)
• Original Assignee: TRW Inc. (Northrop Grumman Corporation)
• Inventors: Cortines, Charles M., Crandall, Danny N., Thompson, Brent B., Beastrom, Keith P.
• Primary Examiner(s): Teska, Kevin J.
• Assistant Examiner(s): FREJD, RUSSELL WARREN
• Application Number:
  US08/122,830
• Time in Patent Office: 1,083 Days
• Field of Search: 364/200, 364/424.03, 364/424.04, 364/580, 364/423, 364/551.01, 364/578, 340/500, 340/52 F, 371/15.1, 73/431, 324/158 R
• US Class Current: 701/31
• CPC Class Codes: G06F 11/2273 Test methods

Abstract

A diagnostic method and apparatus according to the invention locates faulty components in complex real systems in which a high level function can be allocated into lower functional levels with each lower functional level including a plurality of functions. Functional level allocation is repeated until functions correspond to line replaceable units, shop replaceable units, or individual circuit components. A virtual model according to the invention can be defined with parallel functional levels and functions using virtual components so that point-to-point comparison of signals generated by the real system functions on each functional level can be made with signals generated by corresponding virtual components to isolate faulty line replaceable units, shop replaceable units, or individual circuit components. Inputs to the virtual components are the same as the real system inputs provided to the real system functions.

Claims

1. A method of diagnosing failures in a complex real system including a high level function executed by a plurality of hardware components, wherein said high level function functionally transforms at least one input into at least one output, comprising the steps of:

a) allocating said high level function of said real system into a set of first level functions each functionally transforming at least one input into at least one output, wherein said at least one high level input is provided to said input of one first level function, said at least one high level output is generated by an output of another first level function, and said set of first level functions together provide a functional transformation intended for said high level function;

b) allocating at least one first level function into a set of second level functions each functionally transforming at least one input into at least one output, wherein said at least one first level input is provided to an input of one second level function, said at least one first level output is generated by an output of another second level function, and said set of second level functions together providing a functional transformation intended for said at least one first level function;

c) allocating n^th level functions until said n^th level functions correspond to readily serviceable hardware components;

d) creating a plurality of virtual model components for simulating each real system level function, wherein said virtual models have inputs, outputs and functional behavior which parallels the level function being simulated;

e) providing said at least one high level input from said real system to a high level virtual model component; and

f) comparing said at least one high level output from said high level function of said real system to an output of a high level virtual model component.

2. The diagnostic method of claim 1 further comprising the steps of:

g) providing said first level inputs from said first level functions of said real system to corresponding inputs of first level virtual model components if said high level output from said virtual model does not match said at least one high level output of said high level function; and

h) comparing outputs of said first level virtual model components to corresponding outputs of said real system first level functions to identify a faulty first level function.

3. The diagnostic method of claim 2 further comprising the steps of:

i) providing said second level inputs from said real system second level functions subordinate to said faulty first level function to corresponding inputs of second level virtual model components; and

j) comparing outputs of said second level virtual model components to corresponding outputs of said real system second level functions to identify a faulty second level function.

4. The diagnostic method of claim 3 further comprising the steps of:

k) providing n^th level inputs from said real system n^th level functions subordinate to said faulty second level function to corresponding inputs of n^th level virtual model components; and

l) comparing outputs of said n^th level virtual model components to corresponding outputs of said real system n^th level functions to identify a faulty n^th level function.

5. The diagnostic method of claim 4 further comprising the step of:

m) repeating steps g and h until said faulty n^th level function corresponds to said readily serviceable hardware component.

6. The diagnostic method of claim 5 wherein at least one virtual model component models a corresponding real system level function using an on-line model.

7. The diagnostic method of claim 5 wherein at least one virtual model component models a corresponding real system level function using a database.

8. The diagnostic method of claim 5 wherein at least one virtual model component models a corresponding real system level function using look-up tables.

9. The diagnostic method of claim 5 wherein at least one virtual model component models a corresponding real system level function using real-time data.

10. The diagnostic method of claim 5 wherein at least one virtual model component models a corresponding real system level function using off-line models.

11. The diagnostic method of claim 10 wherein said off-line models include complex routines generating parametric equations.

12. The diagnostic method of claim 5 wherein said readily serviceable hardware components are line replaceable units.

13. The diagnostic method of claim 12 further comprising the step of removing the faulty line replaceable unit from said real system.

14. The diagnostic method of claim 13 further comprising the steps of:

n) allocating said faulty n^th level function corresponding to said faulty line replaceable unit into a set of (n+1)^th level functions each functionally transforming at least one input into at least one output, wherein said input to said at least one faulty n^th level is provided to said input of one (n+1)^th level function, said output of said at least one faulty n^th level is generated by said output of another (n+1)^th level function, and said set of (n+1)^th level functions together provide a functional behavior intended for said faulty n^th level function;

o) allocating at least one (n+1)^th level function into a set of (n+2)^th level functions each functionally transforming at least one input into at least one output, wherein said at least one (n+1)^th level input is provided to said input of one (n+2)^th level function, said at least one (n+1)^th level output is generated by an output of another (n+2)^th level function, and said set of (n+2)^th level functions together provide a functional behavior intended for said (n+1)^th level function;

p) allocating (n+m)^th level functions until said (n+m)^th level functions correspond to shop replaceable units;

q) creating a plurality of virtual model components for simulating each level function of said line replaceable unit, wherein said virtual models have inputs, outputs and functional behavior which parallels the level function being simulated;

r) providing an input from an actual use simulator to said real system faulty n^th level function and to a corresponding n^th virtual model component; and

s) comparing said output from said faulty n^th level function to the output of the corresponding n^th level virtual model component.

15. The diagnostic method of claim 14 further comprising the steps of:

t) providing a plurality of inputs from said actual use simulator to said (n+1)^th level functions and said (n+1)^th level virtual model components if said output from said faulty n^th level does not match an output of said corresponding n^th level virtual model component; and

u) comparing outputs of said (n+1)^th level virtual model components to corresponding outputs of said (n+1)^th level function to identify a faulty (n+1)^th level function.

16. The diagnostic method of claim 15 further comprising the steps of:

v) providing a plurality of inputs from said actual use simulator to said (n+2)^th level functions subordinate to said faulty (n+1)^th level function and to corresponding inputs of (n+2)^th level virtual model components; and

w) comparing outputs of said (n+2)^th level virtual model components to corresponding outputs of said (n+2)^th level functions to identify a faulty (n+2)^th level function.

17. The diagnostic method of claim 16 further comprising the steps of:

x) providing inputs from said actual use simulator to (n+m)^th level functions subordinate to said faulty (n+2)^th level function and to corresponding inputs of (n+m)^th level virtual model components; and

y) comparing outputs of said (n+m)^th level virtual model components to corresponding outputs of said (n+m)^th level functions to identify a faulty (n+m)^th level function.

18. The diagnostic method of claim 17 further comprising the step of:

z) repeating steps x and y until a faulty (n+m)^th level function corresponds to a faulty shop replaceable unit.

19. A method of maintaining an aircraft by diagnosing failures using a two level approach, wherein the aircraft includes a high level function executed by a plurality of hardware components, wherein said high level function functionally transforms at least one input into at least one output, and wherein the first maintenance level comprises the steps of:

a) allocating said high level function of said real system into a set of first level functions each functionally transforming at least one input into at least one output, wherein said at least one high level input is provided to said input of one first level function, said at least one high level output is generated by an output of another first level function, and said set of first level functions together provide a functional transformation intended for said high level function;

b) allocating at least one first level function into a set of second level functions each functionally transforming at least one input into at least one output, wherein said at least one first level input is provided to an input of one second level function, said at least one first level output is generated by an output of another second level function, and said set of second level functions together providing a functional transformation intended for said at least one first level function;

c) allocating n^th level functions until said n^th level functions correspond to readily serviceable hardware components;

d) creating a plurality of virtual model components for simulating each real system level function, wherein said virtual models have inputs, outputs and functional behavior which parallels the level function being simulated;

e) providing said at least one high level input from said real system to a high level virtual model component;

f) comparing said at least one high level output from said high level function of said real system to an output of a high level virtual model component;

g) providing said first level inputs from said first level functions of said real system to corresponding inputs of first level virtual model components if said high level output from said virtual model does not match said at least one high level output of said high level function;

h) comparing outputs of said first level virtual model components to corresponding outputs of said real system first level functions to identify a faulty first level function;

i) providing said second level inputs from said real system second level functions subordinate to said faulty first level function to corresponding inputs of second level virtual model components;

j) comparing outputs of said second level virtual model components to corresponding outputs of said real system second level functions to identify a faulty second level function;

k) providing n^th level inputs from said real system n^th level functions subordinate to said faulty second level function to corresponding inputs of n^th level virtual model components;

l) comparing outputs of said n^th level virtual model components to corresponding outputs of said real system n^th level functions to identify a faulty n^th level function; and

m) repeating steps g and h until said faulty n^th level function corresponds to said readily serviceable hardware component.

20. The method of maintaining an aircraft of claim 19 wherein said readily serviceable hardware components are line replaceable units.

21. The method of maintaining an aircraft of claim 20 further comprising the step of removing the readily serviceable hardware component from said real system.

22. The method of maintaining an aircraft of claim 21 wherein the second maintenance level comprises the steps of:

n) allocating said faulty n^th level function corresponding to said faulty line replaceable unit into a set of (n+1)^th level functions each functionally transforming at least one input into at least one output, wherein said input to said at least one faulty n^th level is provided to said input of one (n+1)^th level function, said output of said at least one faulty n^th level is generated by said output of another (n+1)^th level function, and said set of (n+1)^th level functions together provide a functional behavior intended for said faulty n^th level function;

o) allocating at least one (n+1)^th level function into a set of (n+2)^th level functions each functionally transforming at least one input into at least one output, wherein said at least one (n+1)^th level input is provided to said input of one (n+2)^th level function, said at least one (n+1)^th level output is generated by an output of another (n+2)^th level function, and said set of (n+2)^th level functions together provide a functional behavior intended for said (n+1)^th level function;

p) allocating (n+m)^th level functions until said (n+m)^th level functions correspond to shop replaceable units;

q) creating a plurality of virtual model components for simulating each level function of said line replaceable unit, wherein said virtual models have inputs, outputs and functional behavior which parallels the level function being simulated;

r) providing an input from an actual use simulator to said faulty n^th level function and to a corresponding n^th virtual model component;

s) comparing said output from said faulty n^th level function to the output of the corresponding n^th level virtual model component;

t) providing a plurality of inputs from said actual use simulator to said (n+1)^th level functions and said (n+1)^th level virtual model components if said output from said faulty n^th level does not match an output of said corresponding n^th level virtual model component;

u) comparing outputs of said (n+1)^th level virtual model components to corresponding outputs of said (n+1)^th level function to identify a faulty (n+1)^th level function;

v) providing a plurality of inputs from said actual use simulator to said (n+2)^th level functions subordinate to said faulty (n+1)^th level function and to corresponding inputs of (n+2)^th level virtual model components;

w) comparing outputs of said (n+2)^th level virtual model components to corresponding outputs of said (n+2)^th level functions to identify a faulty (n+2)^th level function;

x) providing inputs from said actual use simulator to (n+m)^th level functions subordinate to said faulty (n+2)^th level function and to corresponding inputs of (n+m)^th level virtual model components;

y) comparing outputs of said (n+m)^th level virtual model components to corresponding outputs of said (n+m)^th level functions to identify a faulty (n+m)^th level function; and

z) repeating steps x and y until a faulty (n+m)^th level function corresponds to said shop replaceable unit.

23. In a complex real system including a high level function functionally transforming at least one input into at least one output, wherein said high level function is composed of a plurality of first level functions each functionally transforming at least one input into at least one output, said at least one input of said high level function is provided to one first level function, said at least one output is generated by another first level function, and said functional transformation intended for said high level function is generated by said set of first level functions,

wherein at least one first level function is composed of a set of second level functions each functionally transforming at least one input into at least one output, said input to said at least one first level function is provided to one second level function, said at least one output of said first level function is generated by another second level function, and said functional transformation intended for said first level function is generated by said set of second level functions, and

wherein said at least one second level function can be allocated to n^th level functions until said each level function corresponds to a readily serviceable hardware component, a diagnostic system comprising:

data acquisition means for obtaining inputs to and outputs of said real system level functions;

virtual model means coupled to said data acquisition means for simulating intended functional transformations of each real system level function when provided corresponding inputs and for generating at least one intended output; and

comparing means for comparing intended outputs of each functional level of said virtual model means and actual outputs of corresponding functional levels of said real system to identify faulty hardware components,

wherein said virtual model means initially compares said high level function, then said first level functions, then said second level functions subordinate to a faulty first level function, and then n^th level functions subordinate to a faulty second level function until a faulty level function corresponds to said readily serviceable hardware component.

24. The diagnostic system of claim 23 wherein said data acquisition means includes at least one transducer.

25. The diagnostic system of claim 24 wherein said data acquisition means includes an analog to digital converter.

26. The diagnostic system of claim 23 wherein said virtual model means includes a microprocessor and memory means for storing and executing on-line models.

27. The diagnostic system of claim 23 further including:

display means coupled to said microprocessor and memory means for graphically depicting a location of said faulty hardware component and for generating step-by-step removal instructions.

28. The diagnostic system of claim 27 wherein said step-by-step instructions are pictorial.

29. A diagnostic system for a faulty line replaceable unit having an n^th level function which functionally transforms at least one input into at least one output, wherein said n^th level function is composed of a plurality of (n+1)^th level functions each functionally transforming at least one input into at least one output, said at least one input of said n^th level function is provided to one (n+1)^th level function, said at least one output of said faulty n^th level function is generated by another (n+1)^th level function, and said functional transformation intended for said n^th level function is generated by said set of (n+1)^th level functions,

wherein at least one (n+1)^th level function is composed of a set of (n+2)^th level functions each functionally transforming at least one input into at least one output, said input to said at least one (n+1)^th level function is provided to one (n+2)^th level function, said at least one output of said (n+1)^th level function is generated by another (n+2)^th level function, and said function transformation intended for said (n+1)^th level function is provided by said set of (n+2)^th level functions, and

where in said at least one (n+2)^th level function can be allocated to (n+m)^th level functions until said level functions correspond to shop replaceable units, a diagnostic system comprising:

use simulation means coupled to said line replaceable unit for generating a plurality of simulated input signals;

a virtual model coupled to said simulation means and including virtual components corresponding to said line replaceable unit level function, wherein each virtual component functionally transforms at least one simulated input into at least one intended output;

data acquisition means coupled to said line replaceable unit for obtaining outputs of each line replaceable unit level function;

comparing means coupled to said virtual model means and said data acquisition means for comparing outputs of said line replaceable unit function levels to intended outputs of corresponding virtual components to identify a faulty shop replaceable unit,

wherein said comparing means initially compares said n^th level function, then said (n+1)^th level functions, then said (n+2)^th level functions subordinate to a faulty (n+1)^th level function, and then (n+m)^th level functions subordinate to a faulty (n+2)^th level function until a faulty level function corresponds to said faulty shop replaceable unit.

30. The diagnostic system of claim 29 wherein said data acquisition means includes at least one transducer.

31. The diagnostic system of claim 30 wherein said data acquisition means includes an analog to digital converter.

32. The diagnostic system of claim 29 wherein said virtual model means includes a microprocessor and memory means for storing and executing on-line models.

33. The diagnostic system of claim 29 further including:

display means connected to said microprocessor and memory means for graphically depicting a location of said faulty hardware component and for generating step-by-step removal instructions.

34. The diagnostic system of claim 33 wherein said step-by-step instructions are pictorial.