Granted Patent B2

US 7,146,292 · App. 10/918,688 · Granted Dec 5, 2006

Abstract

Claims (144)

1. A method of evaluating aging of a component, characterized in that it includes the steps of:

a) performing at repeated instants of time (i) during the useful life of the component, the steps of:

measuring values of the elapsed time in operation of the component (t m,i ), at least one entity (I m,i ) indicative of the aging of the component, and the temperature (T m,i ) of the component,

processing the values as measured as a function of a reference temperature (T ref ) to produce reference values (t ref,i ; I m,i ) for said elapsed time in operation of the component (t m,i ) and said at least one entity (I m,i ) indicative of the aging of the component, wherein said reference values (t ref,i ; I m,i ) are normalized values representative of virtual operation of said component at said reference temperature (T ref );

b) generating, starting from said reference values (t ref,i ; I m,i ) for said elapsed time in operation of the component (t m,i ) and said at least one entity (I m,i ) indicative of the aging of the component, an updated prediction model (A i (t) n i ) for said at least one entity over time,

c) predicting, by means of said updated prediction model (A i (t) n i ), a predicted value (I fit ) of said at least one entity at a given time,

d) performing a comparison involving said predicted value (I fit ) and at least one aging threshold, and

e) issuing an aging warning signal if said comparison indicates deviation of said predicted value (I fit ) beyond an acceptable range.

2. The method of claim 1 , characterized in that said component is a laser and said at least one entity is the drive current thereof.

3. The method of claim 1 , characterized in that said step of processing includes the step of producing said reference values (t ref,i ) for the elapsed time in operation of the component (t m,i ) following the relationship:

-

t

ref

,

i

=

∑

i

⁢

⁢

(

t

m

,

i

-

t

m

,

i

-

1

)

⁢

exp

⁡

[

E

a

K

⁢

(

1

T

ref

-

1

T

m

,

i

)

]

where t ref,i and t m,i are said reference value and the measured value for said elapsed time in operation of the component, E a is the activation energy thereof [eV], K is the Boltzmann constant [eV/K], T ref is said reference temperature, T m,i is the actual measured temperature of the component and the temperatures are in Kelvin degrees.

4. The method of claim 1 , characterized in that said step of processing includes the step of producing said reference values (t ref,i ) for the elapsed time in operation of the component (t m,i ) by retrieving said reference values (t ref,i ) in a look-up table for entries represented by measured values (t m,i ) for said elapsed time in operation of the component and measured values (T m,i ) for said actual temperature of the component.

5. The method of claim 1 , characterized in that said step of processing includes the step of producing said reference values (I ref,i ) for said at least one entity indicative of the aging of the component by means of an analytical relationship relating, as a function of temperature, said reference values (I ref,i ) for said at least one entity indicative of the aging of the component to said measured values (I m,i ) for said at least one entity indicative of the aging of the component.

6. The method of claim 5 , characterized in that said analytical relationship is selected from the group consisting of the relationships:

I ref,i =I m,i +C ( T ref −T m,i )

I ref,i =I m,i exp(( T ref −T m,i )/ T a )

where C is a constant value, T a is a scaling temperature value and I ref,i and I m,i are said reference value and said measured value, respectively, for said at least one entity indicative of the aging of the component.

7. The method of claim 1 , characterized in that said step of processing includes the step of producing said reference values (I ref,i ) for said at least one entity indicative of the aging of the component by retrieving said reference values (I ref,i ) in a look-up table for entries represented by measured values (I m,i ) for said at least one entity indicative of the aging of the component and measured values (T m,i ) for said actual temperature of the component.

8. The method of claim 1 , characterized in that said updated prediction model is generated as a drift function of the type A i (t) n i .

9. The method of claim 1 , characterized in that said updated prediction model is a numerical extrapolation model.

10. The method of claim 1 , characterized in that said comparison includes comparing a value (I fit ) for said at least one entity indicative of the aging of the component predicted for a given future time on the basis of said updated prediction model with at least one threshold value defining a limit of a range of acceptable values for operation of said component at said given future time.

11. The method of claim 1 , characterized in that said comparison includes the operations of:

determining a future instant of time where, based on said updated prediction model, a predicted value (I fit ) for said at least one entity indicative of the aging of the component will equal a limit of a range of acceptable values for operation of said component, and

comparing said future instant of time thus determined with a time threshold corresponding to an acceptable useful life for the component.

12. The method of claim 1 , characterized in that said comparison includes the operation of comparing:

a value (I fit ) for said at least one entity indicative of the aging of the component as predicted for a given instant of time on the basis of said updated prediction model, and

a value for said at least one entity indicative of the aging of the component as derived from measurement at said given instant of time.

13. The method of claim 1 , characterized in that the method is carried out without interrupting operation of said component.

14. A computer program product loadable in the memory of computer and including software code portions for performing the method of claim 1 when the product is run on a computer.

15. A system for evaluating aging of a component, characterized in that it includes:

at least one detector unit for measuring, at repeated instants of time (i) during the useful life of the component, values of the elapsed time in operation of the component (t m,i ), at least one entity (I m,i ) indicative of the aging of the component, and the temperature (T m,i ) of the component,

a processing unit for evaluating the aging level of said component, the processing unit being configured for:

a) processing the values measured by said at least one detector unit as a function of a reference temperature (T ref ) to produce reference values (t ref,i ; I m,i ) for said elapsed time in operation of the component (t m,i ) and said at least one entity (I m,i ) indicative of the aging of the component, wherein said reference values (t ref,i ; I m,i ) are normalized values representative of virtual operation of said component at said reference temperature (T ref );

b) generating, starting from said reference values (t ref,i ; I m,i ) for said elapsed time in operation of the component (t m,i ) and said at least one entity (I m,i ) indicative of the aging of the component, an updated prediction model (A i (t) n i ) for said at least one entity over time,

c) predicting, by means of said updated prediction model (A i (t) n i ), a predicted value (I fit ) of said at least one entity at a given time,

d) performing a comparison involving said predicted value (I fit ) and at least one aging threshold, and

e) issuing an aging warning signal if said comparison indicates deviation of said predicted value (I fit ) beyond an acceptable range.

16. The system of claim 15 , characterized in that said component is a laser and said at least one entity is the drive current thereof.

17. The system of claim 15 , characterized in that said processing unit is configured for producing said reference values (t ref,i ) for the elapsed time in operation of the component (t m,i ) following the relationship:

-

t

ref

,

i

=

∑

i

⁢

⁢

(

t

m

,

i

-

t

m

,

i

-

1

)

⁢

exp

⁡

[

E

a

K

⁢

(

1

T

ref

-

1

T

m

,

i

)

]

where t ref,i and t m,i are said reference value and the measured value for said elapsed time in operation of the component, E a is the activation energy thereof [eV], K is the Boltzmann constant [eV/K], T ref is said reference temperature, T m,i is the actual measured temperature of the component and the temperatures are in Kelvin degrees.

18. The system of claim 15 , characterized in that it includes a memory area for storing a look-up table and said processing unit is configured for accessing said memory area and producing said reference values (t ref,i ) the elapsed time in operation of the component (t m,i ) by retrieving said reference values (t ref,i ) in a look-up table for entries represented by measured values (t m,i ) for said elapsed time in operation of the component and measured values (T m,i ) for said actual temperature of the component, wherein said look-up table is stored in said memory area.

19. The system of claim 15 , characterized in that said processing unit is configured for producing said reference values (I ref,i ) for said at least one entity indicative of the aging of the component by means of an analytical relationship relating, as a function of temperature, said reference values (I ref,i ) for said at least one entity indicative of the aging of the component to said measured values (I m,i ) for said said at least one entity indicative of the aging of the component.

20. The system of claim 19 , characterized in that said analytical relationship is selected from the group consisting of the relationships:

I ref,i =I m,i +C ( T ref −T m,i )

I ref,i =I m,i exp(( T ref −T m,i )/ T a )

where C is a constant value, T a is a scaling temperature value and I ref,i and I m,i are said reference value and said measured value, respectively, for said at least one entity indicative of the aging of the component.

21. The system of claim 15 , characterized in that it includes a memory area for storing a look-up table and said processing unit is configured for accessing said memory area and producing said reference values (I ref,i ) for said at least one entity indicative of the aging of the component by retrieving said reference values (I ref,i ) in a look-up table for entries represented by measured values (I m,i ) for said at least one entity indicative of the aging of the component and measured values (T m,i ) for said actual temperature of the component, wherein said look-up table is stored in said memory area.

22. The system of claim 15 , characterized in that said processing unit is configured for generating said updated prediction model as a function of the type A i (t) n i .

23. The system of claim 15 , characterized in that said processing unit is configured for generating said updated prediction model as a numerical extrapolation model.

24. The system of claim 15 , characterized in that said processing unit is configured for performing said comparison by comparing a value (I fit ) for said at least one entity indicative of the aging of the component predicted for a given future time on the basis of said updated prediction model to at least one threshold value defining a limit of a range of acceptable values for operation of said component at said given future time.

25. The system of claim 15 , characterized in that said processing unit is configured for performing said comparison by:

determining a future instant of time where, based on said updated prediction model, a predicted value (I fit ) for said at least one entity indicative of the aging of the component will equal a limit of a range of acceptable values for operation of said component, and

comparing said future instant of time thus determined with a time threshold corresponding to an acceptable useful life for the component.

26. The system of claim 15 , characterized in that said processing unit is configured for performing said comparison by comparing:

a value (I fit ) for said at least one entity indicative of the aging of the component as predicted for a given instant of time on the basis of said updated prediction model, and

a value for said at least one entity indicative of the aging of the component as derived from measurement at said given instant of time.

27. The system of claim 15 , characterized in that the system is configured for operating without interrupting operation of said component.

28. The system of claim 15 , characterized in that the system is associated with said component as an on-board system.

Assignments (12)