o!& 2Q g Implementation of a Model Based Fault

,//v'---//_

-/o!& NASA

Technical

Memorandum

105781

_

2Q

g

......

Implementation of a Model Based Fault Detection and Diagnosis for Actuation Faults of the Space Shuttle Main Engine _=_-

A. Duyar Florida Atlantic University Boca Raton, Florida and T.-H.

= Guo,

W. Merrill

Lewis Research Center Cleveland, Ohio

Prepared Third

..................

for the

Annual

sponsored Cincinnati,

and J. Musgrave

Conference

on Health

by the University Ohio, November

Monitoring

for Space

Propulsion

Systems

of Cincinnati 13-14, 1991

-

(NASA-TM-105781) IMPLEMENTATION A MODEL BASED FAULT DETECTION OIA_NOSIS FOR ACTUATION FAULTS THE SPACE SHUTTLE MAIN ENGINE (NASA)

15

N93-1140I

OF AND OF

Unclas

p G3/14

0126266

,.

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__

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-F-Z-

T

IMPLEMENTATION TECHNIQUE

OF A MODEL

FOR

ACTUATION

BASED

FAULTS

FAULT

DETECTION

OF THE

SPACE

AND

S HLrITLE

DIAGNOSIS MAIN

ENGINE

A. Duyar Mechanical Engineering Department Florida Atlantic University Boca Raton, Florida 33431 T.-H.

Guo,

National

W. Merrill

and J. Musgrave

Aeronautics and Space Administration Lewis Research Center Cleveland,

Ohio

44135

ABSTRACT In a previous detectionand which

study, Guo, Merrill and Duyar, diagnosis system for actuation

is a continuation

of the

previous

1990, reported a conceptual development faults of the space shuttle main engine.

work,

implements

the

developed

fault

of a fault This study,

detection

diagnosis scheme for the real time actuation fault diagnosis of the space shuttle main scheme will be used as an integral part of an intelligent control system demonstration at NASA

Lewis.

and hypothesis

The diagnosis testing

system

utilizes

for actuation,

sensor

a model

based

method

and performance

and

engine. The experiment

with real time identification

degradation

faults.

INTRODUCTION There

is a growing

increased

demand

reliability,

individual

reliabilities

and Lorenzo, focuses

with fault

on the development

the last two

based

fault

detection

Wunnenberg Beard, 1984,

and

1971, Patton

Jones,

analytical

redundancy. sensors

which

has

fault detection

1989,

1977).

As

opposed

to physical

detection

purposes,

model

of the

obtained give

system from

the difference

being the

between

Ge

These

considered. The

the signals

system

capabilities. (FDD)

attention

and

Caglayan,

and

Fang,

schemes

redundancy analytical

system.

control

methods,

considerable

Speyer,

and Sunman,

and the

(MerriU

This paper system

which

the so called

model

system.

detection

Montgomery

performance

be met by improving

and diagnosis

control

of fault

received 1978,

and

enhanced can

and accommodation

an intelligent

development

Wilbers

Potter

based

Clark,

with

demand

and also by an intelligent

for fault

measurements

quantities

1987,

1973,

redundant actual

of the

systems This

diagnostics

of such

approach

Frank,

et al, 1989,

by a mathematical

part

decades

control

components

detection,

of a model

as an integral

During

improved

and maintainability.

of system

1988)

can be used

for

durability

being

1976,

1988,

which

These

1986,

1974,

Wilsky,

measurements

utilizes

signals using

and the

of

from generated

are then compared

is done

measured

and

rely on the idea

uses

signals

Willsky,

Chow

basically

redundancy comparison

(Massoumrfia,

the signals

with

residual being

generatedby the mathematicalmodel. Hence, be def'med of the

as the determination

system

generation The

with

a priori

of residual

basis

each

and

of a fault

model def'ming the effects the residual vector in such Furthermore,

information

quantities

for the isolation

represented

their

by

the

i.e., a signal

faults

fault

detection

cause

has to be unique

schemes

changes

are either

in parameters

of the

system

through

obtained

fi:om a diagnostic

with a fault. A diagnostic model is obtained by deeming that its direction is associated with known fault signatures. to one fault

in order

A set of parity relations or a set of unknown input observers sensitive to a different fault, can be used for this purpose. All the

model

analysis.

is the fault signature,

associated a manner

signature

the model based fault detection and diagnosis can of a system from the comparison of the measurements

of faults

explicitly

or implicitly

of the system.

to accomplish

(Frank,

1990),

based

In the parameter

fault

each

isolation.

assigned

to be

on the assumption

estimation

approach,

that system

parameters are estimated on-line to monitor these changes for fault detection and diagnostics purposes. Therefore, it is a simpler, and a more direct approach than the others. This approach has been used for fault detection in a d.c. motor and pipe system by Filbert and Metzger, 1982. In this

approach

(Isermarm,

fault

decision

1984, Walker

logic

and B aumgarten,

can effectively

be used

in fault

It is believed

that

success

the

of

information

that

accomplished

by incorporating

in the

of the

model

multivariable assumed that component

faulty

parameter no more

faults

different

hypotheses

analyzed

for diagnostics

of the

of some

actuation

of the fault

In this paper, the

model

estimation

a FDD

scheme

depends

on

the

accurate

implementation

previous

be

used

the notion process.

for

type

same

diagnostics

purposes.

of fault parameters

These

at the

Hence,

The

fault

fault

Merrill of either

parameters

parameters

this

study,

this

and Himmelblau,

are estimated

(Duyar, Hdem, in the categories

time.

In

(Watanabe

fault parameters

of faults.

work,

implements

of the nominal

process

the

of the FDD

linear

is presented.

parameters scheme

detection and diagnosis technique Eldem and Saravanan, 1990, Guo, the results

appropriate

by using

a real

and Guo, actuation their

time

1990). It is or sensor or

are estimated

and

is

1983)

based

patterns

on

are then

developed

FDD

development This study, scheme

of an FDD which is a

for the

real

time

of the SSME.

faulty

fault

and

The model of the faulty process def'mes the effects associated is modelled to distinguish the faults, then the residuals carry can

the development of

etc., which

purposes.

diagnosis

of the

parameters

fuel consumption,

In a previous study, Guo, Merrill and Duyar, 1990, reported a conceptual system for actuation faults of the space shuttle main engine (SSME). continuation

physical

logic.

estimation algorithm than one type of fault

can occur

the estimates

199 l) such as efficiency,

diagnosis

modelling of the faulty process. with faults. If the faulty process meaningful

can also employ

is

model

Then,

of the SSME

the

fault

discussed.

Finally,

the

for actuation

faults

of the

diagnosis results SSME

is first presented. scheme

based

obtained are presented.

Next, on

the

through

the

The

fault

used in this study was previously reported in papers .(Duyar, Merrill and Duyar, 1990, Duyar and Eldem, 1991). However,

of the real time implementation

are new and are presented

in this paper.

MODEL

OF THE

It is assumed described

NORMAL

that

PROCESS

the dynamics

by the following

x(n+l) --A x(n) +B

of the SSME

can be modelled

as a discrete

time

Linear system

state equations

(I)

u(n)

(2)

y(n)--C x(n)

where

x, u and y are the kxl

B, C are the nominal

state,

matrices

system is in a-canonical relations hold:

the pxl

input

of the system

form

(Duyar,

and the qxl

with appropriate

Eldem,

Merrill

output

vectors

dimensions.

and Guo,

respectively

and

It is assumed

1990)

such

that

the

that the following

C = [0 :H -1]

A

(3)

= Ao + K H C

(4)

=o

(5)

(n c3,

(6)

-- o for

(HC)nA_K#=0

Here

K is a deadbeat

the observability by It. (HC),

indices

denotes

of

computer

using

developed

by Eldem

the power

level

preburner and

rotary

the

SSME

from

valve ratio,

(OPFV).

(7)

IX I

H are lower

observability

left triangular

index

which

l_j denotes

of the normal

process

1981).

1989,

70% valve

_,-

of HC while

of the valve

oxidizer

l