Document
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b NASA Technical Memorandum 86793
Highly Integrated Digital Electronic Control -
Digital Flight Control,
Aircraft Model Identi-
fication and Adaptive Engine Control
Jennifer L. Baer-Riedhart and Robert J. Landy
(BASA-TH-86793) E I G H L P I Y T E G E A T E C D I G I T A L 8 8 7 - 2 2 6 19
E L E C I R O B I C CC I F l f C L : D I G I T A L E L I G B I COhiTRCL,
Al&CFiAPT RCDEL l G E N T ~ F I C A ! I I C b, A Y D A D A P T I V B
E I G X I I E CCHTBGZ ( A A S A ) 16 F . A v a i l : N T f S Unclas
L C A 0 2 / H P i b O l CSCL 21E Hl/07 0 0 7 6 7 5 3
March 1987 National Aeronautics and Space Administration
NASA Technical Memorandum. 86793
Highly Integrated Digital Electronic Control -
Digital Flight Control, Aircraft Model Identifi-
cation and Adaptive Engine Control
Jennifer L. Baer-Reidhart
Ames Research Center, Dryden Flight Research Facility, Edwards, California
Robert J. Landy
McDonnell Aircraft Company, St. Louis, Missouri
National Aeronautics and
Space Administration
Ames Research Center
Dryden Flight Research Facility
Edwards, California 93523 - 5000
H i g h l y I n t e g r a t e d D i g i t a l E l e c t r o n i c C o n t r o l -
D i g i t a l F l i g h t Control, A i r c r a f t Model I d e n t i f i c a t i o n , and Adaptive Engine C o n t r o l J e n n i f e r L. Baer-Riedhart NASA Ames Research Center, Dryden F l i g h t Research F a c i l i t y , Edwards, C a l i f o r n i a 93523-5000 and Robert J. Landy McDonnell A i r c r a f t Company, b
S t . Louis , M i s s o u r i
ABSTRACT C e n t e r ' s Dryden F l i g h t Research F a c i l i t y i n i t i a t e d t h e h i g h l y i n t e g r a t e d d i g i t a l e l e c t r o n i c c o n t r o l The h i g h l y i n t e g r a t e d d i g i t a l e l e c t r o n i c con- (HIDEC) program. McDonnell A i r c r a f t Company t r o l (HIDEC) program a t NASA Ames Research Center, (MCAIR) i s t h e p r i m e c o n t r a c t o r , w i t h P r a t t & Dryden F l i g h t Research F a c i l i t y i s a m u l t i p h a s e Whi t n e y A i r c r a f t (PWA) and Lear S i e g l e r I n c o r - f l i g h t r e s e a r c h program t o q u a n t i f y t h e b e n e f i t s p o r a t e d ( L S I ) as m a j o r s u b c o n t r a c t o r s . The t e s t o f p r o m i s i n g i n t e g r a t e d c o n t r o l systems. McDonnell a i r c r a f t i s an F-15, m o d i f i e d f o r i n s t a l l a t i o n o f A i r c r a f t Company i s t h e prime c o n t r a c t o r , w i t h d i g i t a l f l i g h t and engine c o n t r o l systems. The U n i t e d Technologies P r a t t R Whitney, and Lear o b j e c t i v e s o f t h e program a r e t o design, i m p l e - S i e g l e r I n c o r p o r a t e d as m a j o r s u b c o n t r a c t o r s . ment , and f l i g h t - t e s t s e l e c t e d i n t e g r a t e d f l i g h t / p r o p u l s i o n c o n t r o l modes which promise s i g n i f i c a n t The NASA F-15A t e s t b e d a i r c r a f t was m o d i f i e d improvements i n a i r c r a f t performance.
f o r t h e H I D E C program by i n s t a l l i n g a d i g i t a l elec- t r o n i c f l i g h t c o n t r o l system (DEFCS) and r e p l a c i n g The HIDEC program i s d i v i d e d i n t o f i v e phases.
t h e s t a n d a r d F l O O (Arab 3 ) enyines w i t h FlOO engine These phases and t h e program schedule a r e shown nodel d e r i v a t i v e (EMD) engines equipped w i t h d i g l - i n F i g . 1. Phase 1 o f t h e HIDEC program i n v o l v e s t a l e l e c t r o n i c e n g i n e c o n t r o l s (DEEC), and i n t e g r a - t h e f l i g h t t e s t i n g o f t h e d i g i t a l e l e c t r o n i c t i n g t h e DEEC's and DEFCS. The m o d i f i e d a i r c r a f t f l i g h t c o n t r o l system (DEFCS) i n t h e NASA F-15 p r o v i d e s t h e c a p a b i l i t y f o r t e s t i n g many i n t e g r a - a i r p l a n e . The DEFCS c o n s i s t s o f a h i g h e r - o r d e r - t e d c o n t r o l modes i n v o l v i n g t h e f l i g h t c o n t r o l s , language d i g i t a l f l i g h t c o n t r o l computer and two engine c o n t r o l s , and i n l e t c o n t r o l s . m o d i f i e d c o n t r o l augmentation system (CAS) analog computers used f o r sensor and a c t u a t o r i n t e r f a c e .
T h i s paper focuses on t h e f i r s t two phases o f As p a r t o f phase 1, t h e DEFCS s o f t w a r e i s p r o - t h e H I n E C program. which a r e t h e d i g i t a l f l i g h t grammed t o p r o v i d e a " f l u t t e r e x c i t e r " f u n c t i o n c o n t r o l s y s t e m l a i r c r a f t model i d e n t i f i c a t i o n t h a t enables t h e p i l o t t o s e l e c t p r e c i s e f r e - (DEFCVAMI) phase and t h e a d a p t i v e engine con- quency sweep and d w e l l i n p u t s t o t h e h o r i z o n t a l t r o l system (ADECS) phase. t a i l s . T h i s f e a t u r e a l l o w s t h e a c q u i s i t i o n o f d a t a f o r i m p r o v i n g t h e mathematical models o f f l i g h t c o n t r o l components and a i r c r a f t r i g i d INTRODUCTION and s t r u c t u r a l modes.
D i y i t a l e l e c t r o n i c c o n t r o l s i n new a i r c r a f t Phase 2 o f HIDEC, c a l l e d t h e a d a p t i v e e n g i n e enhance v e h i c l e preformance by p r o v i d i n g a means c o n t r o l system (ADECS, Ref. l ) , c o n s i s t s o f t h e o f i n t e g r a t i n g t h e f l i g h t and p r o p u l s i o n c o n t r o l d e s i g n , implementation, and f l i g h t t e s t i n g o f an systems. S u b s t a n t i a l b e n e f i t s a r e gained by i n t e g r a t e d f l i g h t and p r o p u l s i o n c o n t r o l mode.
e x p l o i t i n g t h e a d d i t i o n a l c o n t r o l d e v i c e s a v a i l - T h i s mode uses f l i g h t c o n t r o l i n f o r m a t i o n t o a b l e t h r o u g h d i g i t a l c o n t r o l s on advanced design u p t r i m t h e e n g i n e p r e s s u r e r a t i o f o r improved a i r c r a f t . These d e v i c e s i n c l u d e symmetrical and e n g i n e performance. Phase 3 o f t h e program w i l l d i f f e r e n t i a l l y v a r i a b l e canards, v a r i a b l e leading- c o n s i s t o f t h e development and e v a l u a t i o n o f and t r a i l i n g - e d g e f l a p s , v a r i d b l e geometry i n l e t s , s e l e c t e d t r a j e c t o r y guidance a l g o r i t h m s . The two-dimensional t h r u s t v e c t o r i n g and r e v e r s i n g a l g o r i t h m s w i l l be t e s t e d w i t h and w i t h o u t t h e n o z z l e s , and o t h e r c o n t r o l v a r i a b l e s associated w i t h v a r i a b l e c y c l e engines. The c o m p l e x i t y ADECS f e a t u r e s . A d d i t i o n a l ADECS modes and i n v o l v e d i n t h e i n t e g r a t i o n o f t h e s e systems enhancements t o t h e b a s i c f e a t u r e s w i l l be d e v e l - oped and t e s t e d d u r i n g phase 4 o f t h e H I D E C p r o - i s governed by t h e d i g i t a l l o g i c . The i n t e g r a - t i o n o f t h e s e systems enhances a i r c r a f t maneuver- gram. Phase 5 w i l l i n v o l v e e f f o r t s i n t h e area o f a b i l i t y , improves t r a j e c t o r y c o n t r o l f o r t e r r a i n performance-seeking c o n t r o l s w i t h t h e i n t e g r a t i o n f o l l o w i n g , t e r r a i n avoidance, and weapon d e l i v e r y , o f t h e a i r c r a f t i n l e t s t o t h e e n g i n e and f l i g h t c o n t r o l systems. T h i s paper c o n c e n t r a t e s on and s h o r t e n s t a k e o f f and l a n d i n g d i s t a n c e s .
phases 1 and 2 o f t h e HIDEC program, and i n c l u d e s Energy management techniques, when combined d i s c u s s i o n s on t h e ADECS c o n t r o l system design.
w i t h t r a j e c t o r y c o n t r o l , can r e s u l t i n s i g n i f - t h e computational a r c h i t e c t u r e , t h e developmental i c a n t f u e l and c o s t savings.
t e s t i n g , t h e b u i l t - i n - t e s t and i n - f l i g h t i n t e g r i t y To devplop and demonstrat? I n t e g r a t e d f l i g h t management system, and t h e p l a n s f o r t h e f l i g h t t e s t s i n c l u d e d i n these two phases.
and p r o p u l s i on techno1 ogy , NASA Ames Research
M C A I R McDonnel A i r c r a f t Company P r o j e c t i o n s f o r engine performance improvements d u r i n g t h e HIDEC program a r e c o n t a i n e d i n Ref. 1 MUX mu1 ti p l ex and 2.
n a v i g a t i o n c o n t r o l i n d i c a t o r NC I NOMENCLATURE e n g i n e f a n speed N1 A DC a i r d a t a computer e n g i n e f a n speed, c o r r e c t e d t o e n g i n e N1C2 A D E C S a d a p t i v e engine c o n t r o l system i n l e t cond i ti ons A l l I a i r c r a f t model i d e n t i f i c a t i o n e n g i n e f a n speed, c o r r e c t e d N 1 / f i A S a l t e r n a t e shape, A K I e x c i t a t i o n a- l a t e r a l a c c e l e r a t i o n nY amplitude, waveform frequency A(w) normal a c c e l e r a t i o n n2 h u i 1 t - i n t e s t H I T b P p i t c h CAS computer B UC hyd rome hanical backup e n g i n e c o n t r o l PA SC OT programmable asynchronous s e r i a l com- C A S c o n t r o i augmentation system mun i c a t i on t r a n s l a t o r computer
c c c e n t r a l
PC D p i t c h CAS d e f e a t o n i n d i c a t o r d i s p l a y
c I D C o r r e c t
PLA power l e v e r a n g l e c o c k p i t C P PSC performance-seeki ng c o n t r o l s UEEC d i g i t a l e l e c t r o n i c engine c o n t r o l PT 2 f a n i n l e t t o t a l p r e s s u r e U t F C S d i g i t a l e l e c t r o n i c f l i g h t c o n t r o l system f a n d i s c h a r g e t o t a l p r e s s u r e PTZ. 5 d i g i t a l f l i g h t c o n t r o l computer DFCC PT 6 t u r b i n e d i s c h a r g e t o t a l p r e s s u r e e n g i n e model d e r i v a t i v e E I l U PWA P r a t t 8 Whitney A i r c r a f t E PR engine pressure r a t i o r o l l r a t e P EPRc' engine pressure r a t i o command p i t c h r a t e q EPRp e n g i n e pressure r a t i o , p r e d i c t e d p i t c h r a t e change F F T f a s t F o u r i e r t r a n s f o r m RF r a d i o frequency l a t e r a l s t i c k f o r c e F 1 a t RMDU remote m u l t i p l e x / d e m u l t i p l e x u n i t l o n g i t u d i n a l s t i c k . f o r c e r o l l l y a w CAS computer FI ong R / Y r yaw r a t e F PR f a n p r e s s u r e r a t i o s o f t w a r e t e s t f a c i l i t y - f l i g h t c o n t r o l l a b STF -F CL rudder pedal f o r c e Frud ambient t e m p e r a t u r e Tamb F T I T f a n t u r b i n e i n l e t temperature e TH/ E NG t h r o t t l e / e n g i n e F T I T c a f a n t u r b i n e i n l e t temperature conmand TRAJ t r a j ec t o ry h i g h l y i n t e g r a t e d d i g i t a l e l e c t r o n i c H I D E C c o n t r o l t t i m e H009 d a t a bus nomenclature UART u n i v e r s a l asynchronous r e c e i v e r / t r a n s m i t t e r d a t a bus HUD head-up d i s p l a y
v &V v e r i f i c a t i o n and v a l i d a t i o n
I F Ill i n - f l i g h t i n t e g r i t y management engine a i r f l o w , c o r r e c t e d Wac I N S i n e r t i a l n a v i g a t i o n s e t i A M I command 2 e n g i n e a i r f l o w , c o r r e c t e d t o engine i n l e t LS I Lear S i e g l e r I n c o r p o r a t e d Wrap wraparound s o f t w a r e l o g i c a n y l e of a t t a c k m i c r o p r o c e s s o r w i t h 490 kops and 26K memory, and f o u r channels f o r communication; ( 2 ) MIL-STD-1553A ( 3 ) PASCAL as t h e h i g h e r - a n g l e o f a t t a c k p r e d i c t e d m u l t i p l e x i n t e r f a c e ; o r d e r language; and ( 4 ) hardware t h a t enables t h e system t o b e r e c o n f i g u r e d as a t r i p l e x , quadru- a n g l e o f s i d e s l P p l e x , o r d u a l - d u a l system.
p, p r e d i c t e d a n g l e o f s i d e s l A s i g n i f i c a n t f e a t u r e f o r H I D E C i s t h e h i g h e r - order-language c o m p a t i b i l i t y which enables c o s t - s t a b i l a t o r d e f l e c t i o n e f f e c t i v e programming of t h e DFCC f o r t h e subse- q u e n t HIDEC phases.
rudder d e f l e c t i o n The e x e c u t i o n of t h e DFCC e x e c u t i v e program, i n p u t - o u t p u t program, and f l i g h t c o n t r o l laws change t a k e s a p p r o x i m a t e l y one-half o f t h e 12.5-msec d u t y c y c l e t i m e and o n l y about one q u a r t e r o f t h e a v a i l - frequency a b l e memory. Thus t h e r e i s ample c y c l e t i m e and memory a v a i l a b l e t o accomplish i n t e g r a t e d c o n t r o l A I R C R A F T D E S C R I P T I O N l a w c a l c u l a t i o n s i n t h e DFCC f o r t h e HIDEC phases.
The t e s t v e h i c l e f o r t h i s program i s an F-15 Engine a i r p l a n e . m o d i f i e d w i t h a d i g i t a l e l e c t r o n i c f l i g h t c o n t r o l system (DEFCS). The a i r p l a n e i s a The FlOO END e n g i n e (Ref. 3) i s an upgraded high-performance. t w i n - e n g i n e f i g h t e r capable o f v e r s i o n o f t h e FlDO-PW-100 e n g i n e t h a t c u r r e n t l y speeds t o Mach 2.5. The e n g i n e i n l e t s a r e o f t h e two-dimensional e x t e r n a l compression t y p e w i t h powers t h e p r o d u c t i o n F-15 a i r p l a n e s . The e n g i n e i s b u i l t by P r a t t 8 Whitney A i r c r a f t and has a t h r e e raiips, and f e a t u r e v a r i a b l e c a p t u r e area.
company d e s i g n a t i o n o f P W 1128.
The F-15 a i r p l a n e i s powered by two F l O O engine The engine model d e r i v a t i v e (EMD) a f t e r b u r n i n g t u r b o f a n i n c o r p o r a t e s a redesigned fan, r e v i s e d compres- engines equipped w i t h d i g i t a l e l e c t r o n i c engine s o r and combustor, s i n g l e c r y s t a l t u r b i n e b l a d e s c o n t r o l s (DEEC). and vanes, a 16-segment augmentor w i t h 1 i g h t - o f f d e t e c t o r , and a DEEC.
D i g i t a l E l e c t r o n i c F l i g h t C o n t r o l System The DEEC i s a f u l l - a u t h o r i t y d i g i t a l c o n t r o l The DEFCS hardware c o n s i s t s o f a four-channel w i t h an i n t e g r a l hydromechanical backup c o n t r o l .
The DEEC c o n t r o l s t h e gas g e n e r a t o r and augmentor d i g i t a l f l i g h t c o n t r o l computer (DFCC) and two m o d i f i e d c o n t r o l augmentation system analog com- f u e l f l o w s , t h e compressor b l e e d s , t h e v a r i a b l e i n l e t g u i d e vanes, t h e v a r i a b l e s t a t o r s , and t h e p i t t e r s . The d i g i t a l system f e a t u r e s d i g i t a l micro- p r o c e s s o r s f o r decreased volume and reduced cost, v a r i a b l e exhaust nozzle. It i n c o r p o r a t e s l o g i c t h a t p r o v i d e s c l o s e d - l o o p c o n t r o l o f engine a i r - para1 1 e l p r o c e s s i n g a r c h i t e c t u r e f o r increased t h r o u g h p u t , and h i g h e r - o r d e r language f o r b e t t e r f l o w and e n g i n e p r e s s u r e r a t i o (EPR), l i m i t s t h e f a n t u r b i n e i n l e t temperature ( F T I T ) , and i s capa- proyramning e f f i c i e n c y and m a i n t a i n a b i l i t y . The h i g h e r - o r d e r language c u r r e n t l y used f o r t h e DFCC a b l e o f a c c e p t i n g i n p u t s from t h e a i r p l a n e and t h e many e n g i n e sensors. l o r e d e t a i l e d i n f o r m a t i o n on i s PASCAL. Two channels i n t h e DFCC c o n t a i n t h e t h e DEEC i s g i v e n i n Ref. 4.
redundant p i t c h c o n t r o l laws, w h i l e t h e o t h e r t w o channels c o n t a i n t h e redundant r o l l and yaw f l i g h t HIDEC PHILOSOPHY c o n t r o l laws. The m o d i f i e d analog computers pro- v i d e t h e i n t e r f a c e w i t h t h e onboard sensors and The p r i m a r y o b j e c t i v e o f t h e HIDEC program i s a c t u a t o r s . The d i g i t a l system emulates t h e analog F-15 c o n t r o l augmentation system (CAS) so t h a t the t o demonstrate and e v a l u a t e t h e improvements i n performance and m i s s i o n e f f e c t i v e n e s s r e s u l t i n g h a n d l i n g q u a l i t i e s a r e i d e n t i c a l t o those o f a s t a n d a r d F-15 a i r p l a n e . f r o m e n g i n e / a i r f r a m e c o n t r o l i n t e g r a t i o n . The approach was t o implement i n t e g r a t e d engine/ The a v i o n i c s a r c h i t e c t u r e i s shown i n F i g . 2. a i r f r a m e c o n t r o l modes on t h e F-15 a i r p l a n e , con'- The programmable asynchronous s e r i a l communication c e n t r a t i n g on t h e areas of a d a p t i v e engine c o n t r o l t r a n s l a t o r (PASCOT) was i n s t a l l e d i n t h e a i r c r a f t system modes and t r a j e c t o r y guidance modes. A k e y t o a l l o w an i n t e r c h a n g e of i n f o r m a t i o n between the element o f t h e HIDEC program p h i l o s o p h y was t o t h r e e mu1 t i p l e x buses: t h e a i r c r a f t standard HD09 p r o v i d e a c o s t - e f f e c t i v e d e m o n s t r a t i o n o f i n t e - hus on which t h e c e n t r a l computer (CC) communi- g r a t e d c o n t r o l s techno1 ogy. T h i s meant c o n s t r u c - t i n g a t e c h n o l o g y demonstrator a i r c r a f t on which c a t e s w i t h p e r i p h e r a l s such as t h e i n e r t i a l n a v i - t e c h n o l o g i e s c o u l d be i m p l e - g a t i o n system ( I N S ) and t h e a i r d a t a computer, the t h e l a t e s t d i g i t a l mented and e v a l u a t e d e f f i c i e n t l y . I m p l e m e n t a t i o n UART s e r i a l bus t h a t t r a n s f e r s d a t a from t h e DEEC o f t h e proposed c o n t r o l modes was achieved i n a engines (implemented d u r i n g t h e ADECS phase), and c o s t - e f f e c t i v e manner t h r o u g h t h e use o f t e c h - t h e 1553A bus on which t h e DFCC and t h e instrumen- n o l o g i e s developed f o r t h e d i g i t a l f l i g h t c o n t r o l t a t i o n system communicate. The PASCOT p e r m i t s system and d i g i t a l engine c o n t r o l s . The d i g i t a l b o t h OEFCS and CC d a t a t o be sent t o t h e onboard i m p l e m e n t a t i o n p r o v i d e s b o t h a d i r e c t i n t e r f a c e i n s t r u m e n t a t i o n system f o r r e c o r d i n g , and f o r w i t h o t h e r d i g i t a l a v i o n i c s systems and t h e con- t e l e m e t e r i n g t o ground r e c e i v e r s f o r r e a l - t i m e p u t a t i o n a l c a p a b i l i t y r e q u i r e d t o f l i g h t t e s t ~ . i o n i t o r i n yand p o s t f l i g h t d a t a processing.
i n t e g r a t e d f l i g h t and p r o p u l s i o n c o n t r o l modes.
The key f e a t u r e s o f t h e DEFCS a r e ( 1 ) t h e d i g i t a l f l i g h t c o n t r o l computer, a 28002 1 6 - b i t Another key element i n t h e H I D E C program program, w i t h a d d i t i o n a l f l i g h t e v a l u a t i o n s p e r - p h i l o s o p h y was t h e r e d u c t i o n o f p a s t s o c i a l p r e j - formed i n a c o o p e r a t i v e e f f o r t between t h e A i r u d i c e s , t h u s a l l o w i n g the d e m o n s t r a t i o n of more F o r c e and M C A I R . The t e s t phase c o n s i s t e d o f complex c o n t r o l system i n t e g r a t i o n between t h e p i l o t e v a l u a t i o n s o f t h e a i r p l a n e and d a t a a n a l - a i r f r a m e and p r o p u l s i o n components. The p r e j - y s i s t h a t compared t h e DEFCS o p e r a t i o n w i t h t h e u t l i c e s arc! based on the r e l u c t a n c e t o implement a n a l o g CAS.
m a j o r engine c o n t r o l modes i n t h e a i r c r a f t com- p u t e r s . The major components of t h e HIDEC system The NASA F-15 a i r p l a n e was f l o w n w i t h t h e a r e e x i s t i n g hardware ("hardware o f convenience") DEFCS d u r i n g February and March 1985. O n s i x t h a t c o n t a i n a l i m i t e d redundancy l e v e l . There- d e d i c a t e d f l i g h t s f l o w n b y t h r e e d i f f e r e n t NASA f o r e , t h e a r c h i t e c t u r e and system o p e r a t i o n a r e t e s t p i l o t s , t h e DEFCS was t e s t e d t h r o u g h o u t t h e based on a " f a i l - o f f / f a i l - s a f e " p h i l o s o p h y . T h i s c u r r e n t F-15 envelope. The t e s t maneuvers designed t o t h o r o u g h l y check a i r c r a f t f l y i n g q u a l i t i e s were means t h a t i n case o f major f a i l u r e s o f t h e HIDEC f o r m a t i o n f l y i n g , touch-and-go and s i n g l e engine modes o r hardware, t h e o p e r a t i n s system would waveoffs.
r e v e r t t o t h e s t a n d a r d a i r c r a f t (non-HIDEC) Unanimous p i l o t o p i n i o n concluded t h a t t h e F-15 a i r c r a f t h a n d l i n g q u a l i t i e s w i t h DEFCS modes o r t h e b a s i c mechanical systems.
i n s t a l l e d were t h e same as an F-15 w i t h t h e stand- F o r t h e H I D E C program, c r i t i c a l engine c o n t r o l a r d analog c o n t r o l augmentation system (CAS), w i t h t h e e x c e p t i o n t h a t r o l l response and f o r m a t i o n parameters, such as engine p r e s s u r e r a t i o , a r e f l y i n g were somewhat improved r e l a t i v e t o u s i n g commanded from t h e f l i g h t c o n t r c j l computer. I n t h e analog CAS.
l a t e r phases, a d d i t i o n a i engine parameters such as a i r f l o w and f a n t u r b i n e i n l e t temperature a l s o w i l l be commanded from t h e f l i g h t c o n t r o l com- A i r c r a f t model i d e n t i f i c a t i o n . One o f t h e main p u t e r . The l o g i c f o r g e n e r a t i n g these commands concerns i n t h e d e s i g n o f advanced a i r c r a f t i s t h a t o f a c c u r a t e l y modeling t h e a i r c r a f t r i g i d body and i s programmed i n a dual redundant f a i l - o f f manner i n t h e f l i g h t c o n t r o l computers. I n t h e f a i l e d s t r u c t u r a l modes, and f l i g h t c o n t o l components s i t u a t i o n , t h e e n g i n e r e t u r n s t o standard DEEC ( a c t u a t o r s , sensors). I n t h e d e s i g n o f c o n t r o l c o n t r o l o p e r a t i o n . The DEEC i t s e l f c o n t a i n s pro- systems f o r s t a t i c a l l y u n s t a b l e a i r c r a f t . t h e area t e c t i o n from e x c e s s i v e commands t h a t c o u l d r e s u l t o f a c t u a t o r and s t r u c t u r a l mode modeling accuracy from a f l i g h t c o n t r o l computer f a i l u r e o r from i s c r u c i a l .
i n t e r f a c e w i r i n g f a i l u r e s . The s u c c e s s f u l t e s t i n g o f t h e H I D E C / A D E C S phase w i l l r e i n f o r c e t h e s i g n i - The most d e s i r a b l e method of c o n s t r u c t i n g and f i c a n t performance gains t h a t can be r e a l i z e d w i t h v e r i f y i n g math models i s t o compare t h e model response w i t h t h a t o b t a i n e d i n f l i g h t . T h i s was t h e more complex c o n t r o l system i n t e g r a t i o n s w i t h - o u t t h e e x t e n s i v e redundancy l e v e l s . done p r e v i o u s l y b y e q u i p p i n g an a i r c r a f t w i t h " f l u t t e r e x c i t e r " hardware, o b t a i n i n g f l i g h t HIDEC TEST PHASES t e s t d a t a , and r e d u c i n g i t by u s i n g f a s t F o u r i e r t r a n s f o r m (FFT) t e c h n i q u e s t o o b t a i n frequency The c u r r e n t H I D E C program c o n s i s t s o f f i v e responses o f a i r c r a f t and a c t u a t o r performance.
T h i s f l u t t e r e x c i t e r hardware i s t y p i c a l l y q u i t e t e s t phases. Phase 1 o f t h e program c o n c e n t r a t e d p r i m a r i l y on t h e i n s t a l l a t i o n and e v a l u a t i o n o f e x p e n s i v e because i t must be custom designed f o r t h e d i g i t a l f l i g h t c o n t r o l system i n t h e F-15 each p a r t i c u l a r a i r c r a f t i n s t a l 1 a t i o n . A1 s o , a i r p l a n e and an a i r c r a f t model i d e n t i f i c a t i o n once designed and i n s t a l l e d , t h e hardware has (AMI) f l i g h t t e s t s e r i e s . Phase 2 i n v o l v e s t h e v e r y l i m i t e d f l e x i b i l i t y i n changing t h e t y p e development and f l i g h t t e s t o f t h e a d a p t i v e e n g i n e o f e x c i t a t i o n . Conversely, i n c o r p o r a t i o n of a c o n t r o l system (ADECS) modes. The development, f l u t t e r e x c i t e r f u n c t i o n i n t h e f l i g h t c o n t r o l i m p l e m e n t a t i o n , and f l i g h t t e s t o f t h e t r a j e c t o r y system s o f t w a r e i s r e l a t i v e l y i n e x p e n s i v e because no a d d i t i o n a l hardware i s needed. It i s a l s o v e r y guidance c o n t r o l laws and a s s o c i a t e d a i r c r a f t mod- f l e x i b l e because a d d i t i o n a l i f i c a t i o n s a r e p r i m a r y i n phase 3 o f t h e HIDEC t y p e s o f e x c i t a t i o n s program. Phase 4 i n v o l v e s t h e development and can be p r o g r a m e d e a s i l y .
f l i g h t t e s t o f enhanced ADECS modes, coupled work f r o m phase 3. F o r t h e p r e c e d i n g reasons, t h e HIDEC program w i t h t h e t r a j e c t o r y guidance Performance-seeking c o n t r o l s development and extended t h e DEFCS phase 1 t e s t i n g t o i n c l u d e t h e f l i g h t t e s t e v a l u a t i o n c o n s t i t u t e phase 5 o f t h e a i r c r a f t model i d e n t i f i c a t i o n (AMI) t e s t s . These program. D u r i n g t h e course of t h e v a r i o u s program t e s t s demonstrated t h e concept o f o b t a i n i n g ground phases, t h e F-15 a i r p l a n e and s u p p o r t i n g systems and f l i g h t te'st d a t a f o r improved m o d e l i n g accuracy w i l l be m o d i f i e d i n t o a f a c i 1 : t y t e s t b e d a v a i l a b l e by a d d i n g a s o f t w a r e module t o t h e d i g i t a l f l i g h t f o r o t h e r i n t e g r a t i o n - t y p e experiments and r e l a t e d c o n t r o l computer. The method used f o r t h e A M I developmental a c t i v i t i e s . The remainder o f t h i s f l i g h t t e s t s i s summarized i n F i g . 3. The A M I paper w i 1 1 c o n c e n t r a t e on t h e a c t i v i t i e s i n v o l v e d method i s f u n c t i o n a l l y s i m i l a r t o f l u t t e r e x c i t e r s i n phases 1 and 2 of the program. implemented p r e v i o u s l y i n hardware on t h e F-15 and F-18 a i r p l a n e s . F o r t h e H I D E C / A M I a p p l i c a t i o n ,
Phase I - D i g i t a l E l e c t r o n i c F l i g h t C o n t r o l
s i n u s o i d a l commands a r e i s s u e d t o t h e c o l l e c t i v e Sys tem/Ai r c r a f t Model I d e n t i f i c a t i o n (DEFCS/AMI ) h o r i z o n t a l s t a b i l a t o r s . As i n d i c a t e d i n Fig. 3, t h e A M I e x c i t e r module i s one o f s e v e r a l DFCC D i g i t a l e l e c t r o n i c f l i g h t c o n t r o l system.
modules c o n t a i n i n g t h e menu s e l e c t l o g i c , t h e The DEFCS f l i a h t t e s t DhaSe v e r j f i e d t h e o o e r a t i o n f a d e - i n c i r c u i t r y . l i m i t e r s , and an a u t o m a t i c disengage f u n c t i o n . The r e s u l t i n g AMI e x c i t a t i o n o f t h e d i g i t a i f l i g h t i o n t r o l system i n t h e NASA i s i n p u t t o t h e f l i g h t c o n t r o l laws i m m e d i a t e l y F - 1 5 a i r p l a n e and expanded t h e DEFCS f l i g h t enve- b e f o r e i s s u i n g a s t a b i l a t o r d e f l e c t i o n command t o l o p e t o t h a t r e q u i r e d f o r t h e H I D E C program. The DEFCS system had p r e v i o u s l y f l o w n under a McDonnell t h e s t a b i l a t o r s e r i e s servos.
A i r c r a f t Company ( M C A I R ) research and development F i g u r e 4 shows t h e H I D E C / A M I crew s t a t i o n con- t h e FTIT l i m i t t o p r e v e n t r e d u c t i o n i n e n g i n e l i f e , f i g u r a t i o n . A c o n t r o l panel was added t o s e l e c t w h i c h r e s u l t s from t h e e n g i n e b e i n g o p e r a t e d above t h e AMI mode and t o d e f e a t t h e p i t c h C A S when t h e FTIT l i m i t .
d e s i r e d . Two d e s t i n a t i o n l o c a t i o n s i n t h e stand- a r d F - 1 5 n a v i g a t i o n c o n t r o l i n d i c a t o r (NCI) a r e !<hen EPR i s uptrimmed, i n c r e a s e d t h r u s t i s used f o r e n t e r i n g A M I data, such as t h e frequency o b t a i n e d a t t h e expense o f reduced e n g i n e s t a l l range f o r t h e e x c i t a t i o n sweep, sweep r a t e , and margin. S i g n i f i c a n t s t a l l m a r g i n i s n o r m a l l y a m p l i t u d e o f t h e sweep (which can be frequency b u i l t i n t o t h e e n g i n e c o n t r o l schedules. A l a r g e dependent). An u p f r o n t panel was added t o show p a r t o f t h i s margin i s designed t o accommodate t h e p i l o t when t h e system was o p e r a t i n g o r i n t h e i n l e t d i s t o r t i o n produced a t h i g h a n g l e s o f a t t a c k r e s e t mode, whether t h e p r e v i o u s e x c i t a t i o n was o r s i d e s l i p . I n t h e ADECS mode, some o f t h e s t a l l t e r m i n a t e d abnormally, and which AMI modes h e r e m a r g i n r e s e r v e d f o r i n l e t d i s t o r t i o n i s used t o s e l e c t e d (such as p i t c h , CAS d e f e a t , and a l t e r - i n c r e a s e t h r u s t i n r e g i o n s of l o w d i s t o r t i o n .
When t h e i n l e t d i s t o r t i o n i s h i g h , EPR i s reduced n a t e e x c i t a t i o n shapes). F o l l o w i n g p r o p e r AMI and s t a l l margins a r e r e s t o r e d . For more i n f o r - mode setup, t h e p i l o t must depress t h e c o u p l e m a t i o n on t h e s t a b i l i t y a u d i t s and d e f i n i t i o n o f b u t t o n on t h e t h r o t t l e t o cause t h e e x c i t a t i o n s i g n a l t o be s e n t t o t h e s t a b i l a t o r . The paddle t h e amount of s t a l l m a r g i n a v a i l a b l e , see Refs. 1
t
and 2.
s w i t c h on t h e s t i c k can be used as an emergency disengage i f t h e p i l o t encounters a problem d u r i n g Subsonic u p t r i m i s implemented as shown i n t h e A M I t e s t .
F i g . 6. The necessary c o n t r o l laws a r e i n c o r - The f l i g h t t e s t i n g o f t h e AMI modes i n c l u d e s a p o r a t e d i n t o t h e d i g i t a l f l i g h t c o n t r o l computer.
range o f Nach numbers from 0.2 t o 1.2 and a l t i t u d e s When p r e d i c t e d a n g l e o f a t t a c k and s i d e s l i p angles from 5.000 t o 30,000 ft. Tne F-15 t e s t a i r c r a f t a r e moderate, t h e c o n t r o l l e r i s s u e s an EPR comnand i s e x t e n s i v e l y i n s t r u m e n t e d t o g a t h e r a l l p e r - t o t h e engine, c a u s i n g t h e e n g i n e t o o p e r a t e c l o s e r t i n e n t a i r c r a f t m o t i o n , s u r f a c e d e f l e c t i o n , and t o t h e s t a l l l i n e . The c o n t r o l l e r senses a i r f r a m e p i t c h , r o l l and yaw r a t e s , and a c c e l e r a t i o n s t o a c t u a t o r i n p u t - o u t p u t i n f o r m a t i o n . The NASA ground s t a t i o n 4s c a p a b l e o f o e r f o r m i n g " r e a l - p r e d i c t a n g l e o f a t t a c k and s i d e s l i p a n g l e s i n t h e t i n e " FFT's which can be c a l c i l l a t e d i n about immediate f u t u r e . When these p r e d i c t e d angles 30 seconds f o l l o w i n g a frequency sweep t e s t .
become l a r g e , t h e c o n t r o l l e r w i l l i m m e d i a t e l y wash The FFT's a r e used on s e l e c t e d sweeps t o v e r i f y o u t t h e u p t r i m s i g n a l i n a well-behaved t r a n s i e n t t h a t good d a t a i s b e i n g generated d u r i n g a p a r - w i t h o u t s t a l l i n g t h e engine.
t i c u l a r t e s t p o i n t , and t h a t no undetected problems e x i s t . The d e t a i l s o f t h e ADECS EPR u p t r i m l o g i c t o be implemented i n t h e DFCC a r e d e s c r i b e d i n The p r i n c i p a l d a t a r e d u c t i o n i s done p o s t - Ref. 2. The EPR u p t r i m i s based on t h e minimum o f the maximum amount o f EPR a l l o w a b l e , f o r i n c r e a s e d f l i g h t u s i n g f l i g h t d a t a tapes and r e a l - t i m e i n f o r n a t i o n from t h e f l i g h t . The r e s u l t s from performance and t h e maximum amount o f EPR a l l o w - t h e f l i g h t t e s t d a t a a r e used t o i l l u s t r a t e t h e a b l e f o r engine s t a l l c o n s i d e r a t i o n s . Implemen- c a p a b i l i t y o f i m p r o v i n g math models o f t h e a i r - t i n g t h i s c o n t r o l l a w r e q u i r e s b o t h a i r f r a m e c r a f t and i t s f l i g h t c o n t r o l components u s i n g i n f o r m a t i o n ( a n g l e o f a t t a c k , s i d e s l i p , and Mach t h p A M I t e c h n i q u e . number) and engine d a t a ( a i r f l o w , f a n speed, and p r e s s u r e s a t t h e engine f a c e ) .
PHASE 2 - A d a p t i v e Engine C o n t r o l System (ADECSL
ADECS modes implementation. The HIDEC a r c h i t e c - The H I D E C / A D E C S phase i s designed t o demon- 7.
t u r e used f o r t h e ADECS modes i s shown i n F i g .
The PASCOT has a d d i t i o n a l c a p a b i l i t y as a m u l t i - s t r a t e improved engine performance u s i n g f l i g h t c o n t r o l i n f o r m a t i o n which has n o t been p r e v i o u s l y p l e x bus c o n t r o l l e r u n i t t o t r a n s f e r t h e i n f o r - a v a i 1 a b l e f o r engine c o n t r o l o p e r a t i o n . Informa- m a t i o n f l o w among t h e a i r c r a f t sensors (H009 bus), t o t h e d i g i t a l f l i g h t c o n t r o l computer (1553 bus), t i n n exchange i s f a c i l i t a t e d by t h e use o f d i g i t a l and t h e d i g i t a l e l e c t r o n i c engine c o n t r o l l e r
systems on t h e a i r p l a n e - t h e DEFCS f o r f l i g h t
DEEC f o r engine c o n t r o l . I n the ( s e r i a l databus). The PASCOT a l s o a c t s as an c o n t r o l , and t h e i n t e r f a c e u n i t f o r t h e HIDEC c o n t r o l panels.
ADECS u p t r i m mode, a d d i t i o n a l t h r u s t i s o b t a i n e d a t i n t e r m e d i a t e and h i g h e r power s e t t i n g s by d e c r e a s i n g t h e n o z z l e t h r o a t area t o i n c r e a s e F i g u r e 8 d e t a i l s t h e ADECS i m p l e m e n t a t i o n , i n c l u d i n g where t h e ADECS c o n t r o l laws and e n g i n e p r e s s u r e r a t i o . Increased engine pres- i n - f l i g h t i n t e g r i t y management s o f t w a r e r e s i d e , s u r e r a t i o r e s u l t s i n increased engine t h r u s t .
and g i v e s t h e d a t a r a t e s f o r communication among ADECS modes. A t y p i c a l fan map i n Fig. 5. t h e key ADECS system computers. The ADECS con- J laws a r e computed i n b o t h t h e p i t c h A and 8 i I 1 u s t r a t e s what happens d u r i n g subsonic u p t r i m . t r o l Fan p r e s s u r e r a t i o (FF'R) and engine p r e s s u r e r a t i o channels w i t h i n t h e DFCC when b o t h t h e HIDEC and ADECS modes a r e s e l e c t e d . The b u i l t - i n t e s t ( E P R ) a r e r e l a t e d , d i f f e r i n g o n l y i n t h e bypass d u c t p r e s s u r e l o s s e s . T h r u s t i s i n c r e a s e d by ( B I T ) , i n - f l i g h t - i n t e g r i t y management ( I F I I I ) i n c r e a s i n y EPR a l o n g J c o n s t a n t , c o r r e c t e d f a n t e s t , and r e l a t e d s a f e t y t e s t s f o r t h e ADECS speed l i n e . T h i s i s accomplished w i t h l i t t l e modes a r e a l s o executed i n t h i s manner. Com- r e d u c t i o n i n engine a i r f l o w . Because h i g h e r fan mands a r e t h e n i s s u e d from t h e DFCC t h r o u g h t h e t u r b i n e i n l e t temperatures ( F T I T ) a r e r e q u i r e d , PASCOT t o t h e DEEC.
f o r t h e i n i t i a l ADECS t e s t s t h i s mode i s used only The a i r p l a n e crew s t a t i o n c o n f i g u r a t i o n f o r when t h e engine i s n o t on t h e F T I T l i m i t . Uptrim The HIDEC c o n t r o l i s a l l o w e d u n t i l t h e normal maximum FTIT l i m i t i s t h i s phase i s shown i n F i g . 9.
panel i s used t o a c t i v a t e t h e HIDEC modes, t o reached, t h e n t h e u p t r i m i s h e l d c o n s t a n t along
s e l e c t t h e e n g i n e ( s ) - l e f t , r i g h t , o r b o t h - t o
4 . v a l i d a t e t h e r e c e i v e t h e ADECS command(s), and t o s e l e c t t h e a. ADECS c o n t r o l laws A U E C S mode and t h e submodes (EPR, o r a c o m b i n a t i o n b. s a f e t y f e a t u r e s o f EPR and F T I T ) f o r a p a r t i c u l a r t e s t sequence.
c. c o u p l e / u n c o u p l e c r i t e r i a , Data e n t r y l o c a t i o n s through t h e N C I Panel a r e p r o v i d e d t o i n i t i a t e B I T ' S and t o e n t e r r e v i s e d r e s o l v e any t h r o u g h p u t t i m i n g problems. 5.
ADECS d a t a f o r use i n the DFCC. There a r e f o u r d e s t i n a t i o n e n t r i e s i n the NC! c o n v e r t e d t o s e l e c t The i n t e g r a t i o n t e s t i n g i d e n t i f i e s and e l i m i n a t e s r e v i s e d ADECS parameter d a t a from s t o r e d values i n most o f t h e HIDEC system i n t e r f a c e problems.
t h e DFCC, p r o v i d i n g great f l e x i b i l i t y f o r t h e f l i g h t t e s t experiments. The HCAIR manned s i m u l a t i o n f a c i l i t y i s used as p a r t o f t h e V&V t e s t i n g f o l l o w i n g t h e i n t e g r a - The u p f r o n t panel d i s p l a y s ADECS system t i o n t e s t i n g i n t h e STF/FCL. The manned simula- c o u p l i n g , I F I M f a i l u r e , and automatic commands t i o n f a c i l i t y p r o v i d e s a 2 0 - f t dome f o r s c e n i c p r o j e c t i o n s and a h i g h e r f i d e l i t y s i m u l a t i o n w i t h d e s t i n a t i o n ( s ) - t o t h e engine c o n t r o l (TH/ENG), a s i m u l a t e d F-15 crew s t a t i o n . The m a j o r HIDEC o r t o t h e f l i g h t c o n t r o l system, o r t o both. The c o u p l e command b u t t o n i s on t h e t h r o t t l e l e v e r and hardware components (DFCC, CAS computers, PASCOT, t h e emergency d i s c o n n e c t f o r t h e system i s t h r o u g h CC, N C I , and HIDEC p a n e l s ) a r e i n c l u d e d i n t h e t h e paddle s w i t c h on the c o n t r o l s t i c k . manned s i m u l a t i o n t e s t s f o r a f i n a l c e r t i f i c a t i o n o f t h e HIDEC system b e f o r e d e l i v e r y t o t h e a i r - ADECS v e r i f i c a t i o n and Val i d a i i o n process. The c r a f t . The i i i D E C manned s i m u l a t i o n t e s t i n g d i a - ADECS phase o f t h e HIUEC program e n t a i l s s o f t w a r e gram i s shown i n F i g . 11. The CYBER computer con- a d d i t i o n s and m o d i f i c a t i o n s t o b o t h t h e a i r f r a m e n e c t e d w i t h t h e f a c i l i t y a l l o w s h i g h e r f i d e l i t y computers ( d i g i t a l f l i g h t c o n t r o l computer and models of t h e a i r c r a f t , a i r c r a f t sensors, engine, c e n t r a l computer) and t o t h e DEEC computer. The DEEC, and i n l e t s t o be used t h a n was p o s s i b l e i n m o d i f i c a t i o n s t o t h e s e systems were t h o r o u g h l y t h e STF-FCL s i m u l a t i o n . The o b j e c t i v e s o f t h e v e r i f i e d and v a l i d a t e d p r i o r t o f l i g h t . T h i s manned h a r d w a r e - i n - t h e - l o o p s i m u l a t i o n a r e s e c t i o n d e s c r i b e s t h e key elements o f t h e v e r i - as f o l l o w s : f i c a t i o n and v a l i d a t i o n ( V A ' J ) process b e f o r e i n s t a l l a t i o n o f t h e equipment on t h e a i r c r a f t . 1. v e r i f y p r o p e r o p e r a t i o n o f t h e ADECS It a l s o d e s c r i b e s t h e b u i l t - i n t e s t ( B I T ) and c o n t r o l laws under r e a l i s t i c p i l o t i n - f l i g h t - i n t e g r i t y management ( I F I M ) f e a t u r e s i n p u t s t h r o u g h o u t f l i g h t envelope, f o r i n s t a l l e d m o n i t o r i n g and checkout o f t h e 2. v e r i f y p r o p e r o p e r a t t o n and s u i t a b i l i t y H I D E C system o p e r a t i o n .
o f ADECS s a f e t y f e a t u r e s , The DFCC, CC, and DEEC computers a l l undergo 3. f a m i l i a r i z e t h e p i l o t w i t h t h e ADECS i n d i v i d u a l module t e s t i n g and module i n t e g r a t i o n t e s t s . These v e r i f y t h a t t h e code i s programmed c o n t r o l f u n c t i o n s , c o r r e c t l y t o compute the a p p r o p r i a t e v a r i a b l e s and 4. assess ADECS performance b e n e f i t s .
l o g i c , and t h a t a l l i n t e r f a c e s between modules a r e c o r r e c t . The modual t e s t i n g e s t a b l i s h e s t h e mem- o r y and t h r o u g h p u t ( d u t y c y c l e t i m e ) requirements T e s t i n g i n t h e manned s i m u l a t i o n f a c i l i t y i s t h e f i n a l s t e p i n t h e V & V process b e f o r e d e l i v e r y f o r each computer.
o f t h e hardware t o t h e a i r c r a f t . A t t h e c l o s e o f The n e x t s t e p i n the V A V process i s t h e HIDEC t h e s e t e s t s t h e s o f t w a r e i s " f r o z e n " i n i t s con- f i g u r a t i o n . Any changes t o t h e f l i g h t - c r i t i c a l system i n t e g r a t i o n t e s t i n g . The DEEC c o n t r o l l e r s s o f t w a r e a f t e r c o m p l e t i o n o f t h e manned s i m u l a t i o n a r e t e s t e d w i t h t h e PASCOT m u l t i p l e x bus c o n t r o l i i n i t t o v e r i f y t h e proper i n t e r f a c e s so t h a t t h e t e s t s may r e q u i r e a r e t e s t i n t h e manned simula- t i o n f a c i l i t y f o r c e r t i f i c a t i o n .
a i r c r a f t computer (DFCC) can exchange i n f o r m a t i o n w i t h and i s s u e commands t o t h e DEEC's. The remainder o f t h e H I D E C equipment i s t e s t e d as a ADECS ground t e s t , maintenance f u n c t i o n s , and system a t t h e M C A I R software t e s t f a c i l i t y - f l i g h t b u i 1 t - i n - t e s t s . Once t h e HIDEC equipment i s c o n t r o l l a b (STF-FCL). The t e s t c o n f i g u r a t i o n i s 7 n s t a I l e d on t h e a i r c r a f t . t e s t s must be performed i l l u s t r a t e d i n F i g . 10 and i n c l u d e s t h e DFCC, CC, t o d e t e r m i n e i f i t i s f u n c t i o n i n g p r o p e r l y . The P A S C O T , c o n t r o l panels, and N C I . Models o f t h e t e s t s a r e r e q u i r e d f o r checkout f o l l o w i n g equip- a i r c r a f t . atmosohere. enaine. DEEC. and i n l e t s ment i n s t a l l a t i o n o r some system anomaly, and as r e s i d e i n t e h o s t H A R R I S computer: The o b j e c - an a u t o m a t i c p r e f l i g h t t e s t .
t i v e s o f t h s i n t e g r a t i o n t e s t a r e as f o l l o w s : To s a t i s f y t h e need f o r t h e m a n u a l l y r u n t e s t s 1. v a l d a t e CC, PASCOT, DFCC, i n d i c a t o r f o l l o w i n g i n i t i a l i n s t a l l a t i o n , a ground t e s t 1 y h t s and c o n t r o l ?anel i n t e r f a c e s , f u n c t i o n and a maintenance f u n c t i o n a r e i n c o r - p o r a t e d i n t h e HIDEC system DFCC and CC s o f t w a r e .
2. Val d a t e 1553 & H009 nux bus o p e r a t i o n , The ground t e s t f u n c t i o n a l l o w s t h e ADECS s o f t w a r e EPR u p t r i m s i g - t o be o p e r a t e d on t h e ground and 3. Val d a t e use o f the N C I t o n a l s s e n t t o t h e DEEC. The p r o p e r f u n c t i o n i n g a . s e l e c t d i f f e r e n t g a i n s o f t h e HIDEC system can be assessed by m o n i t o r i n g b . read memory l o c a t i o n s system v a r i a b l e s u s i n g mux m o n i t o r s and i n s t r u m e n - C . p e r f o r m d i a g n o s t i c maintenance f u n c - t a t i o n system o u t p u t s . Using t h e N C I panel key- t i o n s board and d i s p l a y , t h e maintenance f u n c t i o n a l l o w s d . s e l e c t yround t e s t mode access t o CC and DFCC s e l e c t e d memory l o c a t i o n s e . s e l e c t a v i o n i c p r e f l i g h t B I T f o r a l t e r i n g them and r e a d i n g d a t a from t h e DFCC f . d i s p l a y f a i l e d p r e f l i g h t t e s t n w i o e r , and CC f o r t r o u b l e s h o o t i n g . F o r t h e ADECS f l i g h t phase, t h i s f u n c t i o n a l s o a l l o w s v a r i o u s parame- ADECS fli h t s . The f l i g h t t e s t c o n s i s t s o f t e r s and schedules t o be s e l e c t e d , and access t o both- g acce e r a t i o n s , and s e l e c t e d f l i g h t t e s t t h e DFCC and CC f o r v e r i f i c a t i o n o f t h e s o f t w a r e maneuvers f o r e v a l u a t i n g t h e system between 10,000 v e r s i o n and checksums. and 40,000 ft a l t i t u d e s a t speeds r a n g i n g between Mach 0.3 and 2.0. Hore d e t a i l e d i n f o r m a t i o n The b u i l t - i n t e s t s can be i n i t i a t e d b e f o r e r e g a r d i n g t h e p r e d i c t e d performance o f t h e each t e s t f l i g h t t o a u t o m a t i c a l l y check t h e f o l - HIDEC modes i s i n Refs. 1 and 2.
l o w i n g : PASCDT-initiated BIT, DFCC/PASCOT/CC MUX i n t e r f a c e , DFCC power-up B I T , ADC v a l i d i t y , INS F u t u r e p l a n s f o r t h e HIDEC program i n v o l v e v a l i d i t y , DFCC/PASCOT/DEEC MUX i n t e r f a c e , and DEEC r e s e a r c h i n t h e area o f t r a j e c t o r y guidance. The power-up B I T . f u r t h e r development and e v a l u a t i o n o f s e l e c t e d guidance a l g o r l t h m s , such as o p t i m a l guidance, ADECS i n - f l i g h t i n t e g r i t y management/coupl i n q o p t i m a l i n t e r c e p t i o n , energy management (minimum c r i t e r i a . The HIDEC system, i n t h e ADECS mode, time/minimum f u e l ), and maneuver a u t o p i l o t t e c h - iI n u s t pass an e x t e n s i v e s e t o f I F I M t e s t s and n i q u e s w i l l a i d i n t h e e v a l u a t i o n o f t h e ADECS modes. The a l g o r i t h m s w i l l be e v a l u a t e d i n t h e coupl i n g c r i t e r i a b e f o r e a1 l o w i n g commands t o manual mode and automatic mode, w i t h and w i t h o u t pass from t h e a i r c r a f t DFCC t o t h e (DEEC). The I F I M t e s t s and c o u p l i n g c r i t e r i a l o g i c a r e a c t i v e t h e ADECS modes, and w i l l p r o v i d e a d d i t i o n a l t whenever t h e HIDEC system i s on and t h e modes a r e i n f o r m a t i o n on t h e b e n e f i t s o f e n g i n e / a i r f r a m e i n t e g r a t i o n technology. The HIDEC F-15 a i r c r a f t coupled. The f o l l o w i n g IFIM checks must be passed b e f o r e a1 l o w i n g coupl i n g between t h e DFCC and DEEC: w i l l p r o v i d e a t e s t f a c i l i t y f o r d e v e l o p i n g and e v a l u a t i n g t h e t r a j e c t o r y guidance a l g o r i t h m s 1. DEFCS s e l f checks, u s i n g a ground-based computer and sending t h e com- mand i n f o r m a t i o n t o t h e a i r c r a f t , w i t h t h e p o t e n - 2. C e n t r a l computer s e l f checks, t i a l o f t r a n s f e r r i n g t h e f i n a l a l g o r i t h m s t o an onboard a u x i l i a r y a i r b o r n e computer. Performance- advanced ADECS modes t o be 3. H009 m u l t i p l e x bus checks, seeking c o n t r o l s and developed a r e discussed i n Ref. 1 .
4. PASCOT s e l f checks, CONCLUDING REMARKS 5. 1553 m u l t i p l e x bus checks, The o b j e c t i v e o f t i l e HIDEC program i s t o demon- 6. DEEC s e l f checks s t r a t e and e v a l u a t e t h e improvements i n p e r f o r m - ance and m i s s i o n e f f e c t i v e n e s s r e s u l t i n g from a. c r i t i c a l f a i l u r e i n d i c a t i o n s b. f a u l t i n d i c a t o r s , e n g i n e / a i r f r a m e c o n t r o l i n t e g r a t i o n . The approach uses t h e t e c h n o l o g i e s b e i n g developed i n t h e areas 7 . Wraparound c r o s s checks o f d i g i t a l f l i g h t c o n t r o l systems and d i g i t a l e n g i n e c o n t r o l s t o implement i n t e g r a t e d e n g i n e / a. D F C C / P A S C O T / C C b. DFCC/PASCOT/DEEC/CC a i r f r a m e c o n t r o l modes. The program p h i l o s o p h y and course o f a c t i o n have been s u c c e s s f u l i n To a l l o w c o u p l i n g between t h e DFCC and DEEC d e v e l o p i n g an i n t e g r a t e d e n g i n e / a i r f r a m e t e s t f o r t h e ADECS modes, t h e f o l l o w i n g c r i t e r i a must program i n a c o s t - e f f e c t i v e manner.
be met: Phase 1 t e s t i n g o f t h e d i g i t a l f l i g h t c o n t r o l system developed t h e b a s i c HIDEC a r c h i t e c t u r e and 1. c o r r e c t c o n t r o l panel switches a r e e v a l u a t e d t h e o p e r a t i o n o f t h e DEFCS i n t h e NASA i n i t i a t e d , F-15 a i r p l a n e . The t e s t s Were s u c c e s s f u l , w i t h no m a j o r d i f f e r e n c e s n o t e d between t h e d i g i t a l f l i g h t 2. more t h a n one second has passed a f t e r c o n t r o l system and t h e s t a n d a r d F-15 a n a l o g CAS s w i t c h i n i t i a t i o n .
system. The a i r c r a f t model i d e n t i f i c a t i o n f l i g h t t e s t s p r o v i d e a i r f r a m e a e r o s e r v o e l a s t i c f l i g h t 3. t h r o t t l e c o u p l e b u t t o n i s depressed each d a t a t o compare w i t h math models b y u s i n g a " s o f t - t i m e ADECS mode c o u p l e i s d e s i r e d , ware e x c l t a t i o n system" t o e x c i t e t h e a i r p l a n e 4. no HIDEC system I F I M f a u l t s a r e i n d i c a t e d , s t r u c t u r a l modes.
Phase 2 t e s t i n g c o n c e n t r a t e s on t h e ADECS con- 5.. no a i r c r a f t system f a u l t s a r e i n d i c a t e d , t r o l modes. The development o f t h e c o n t r o l modes and l o g i c demonstrates t h e i n t e g r a t i o n necessary 6. a i r c r a f t a n g l e o f a t t a c k i s w i t h i n spec- between t h e a i r f r a m e and p r o p u l s i o n systems. The i f i e d l i m i t s , i n d i - v e r i f i c a t i o n and v a l i d a t i o n process i n v o l v e s v i d u a l module t e s t i n g . module i n t e g r a t i o n t e s t i n g , 7 . l a n d i n g - g e a r - u p d i s c r e t e i s p r e s e n t ( o r and hardware bench i n t e g r a t i o n t e s t s c u l m i n a t i n g s i m u l a t e d ) , i n t h e manned h a r d w a r e - i n - t h e - l o o p s i m u l a t i o n 8. wraparound m u l t i p l e x channels a r e t e s t s . The B I T and I F I N f e a t u r e s p r o v i d e a means o f checking t h e i n t e g r i t y o f t h e v a r i o u s H I D E C opera t i ng .
systems b o t h on t h e ground and I n f l i g h t , b e f o r e The checks a r e v e r i f i e d as o p e r a t i o n a l d u r i n g and d u r i n g HIDEC mode o p e r a t i o n s . F i n a l v a l i d a - f o l l o w i n g HIDEC t i o n o f t h e HIDEC systems i s performed d u r i n g t h e ground t e s t s on t h e a i r c r a f t equipment i n s t a l l a t i o n . C e r t a i n subsets o f t h e s e t h e a i r c r a f t ground t e s t s , t o b e f o l l o w e d by t e s t s a r e checked b e f o r e each f l i g h t u s i n g t h e t h e f l i g h t t e s t s .
b u i l t - i n t e s t f u n c t i o n d e s c r i b e d e a r l i e r .
The NASA F-15 a i r c r a f t i s b e i n g developed as a ZYonke, W. A., T e r r e l l , L. A., and Myers, L. P., n a t i o n a l f a c i l i t y " t e s t - b e d ' ' f o r f l i g h t and p r o - " I n t e g r a t e d F1 i g h t / P r o p u l s i o n C o n t r o l : A d a p t i v e p u l s i o n i n t e g r a t i o n and r e l a t e d e x p e r i m e n t s . The E n g i n e C o n t r o l System Mode," A I A A Paper 85-1425, a r c h i t e c t u r e and t e c h n i q u e s developed d u r i n g t h e J u l y 1985.
HIDEC program w i l l p r o v i d e t h e f l e x i b i l i t y t o a l l o w g e n e r i c r e s e a r c h t o be conducted i n t h e 3Myers, L. P. and Burcham, F. W., Jr., " P r e l i m i n a r y e n g i n e / a i r f r a i i e i n t e g r a t i o n t e c h n o l o g y area. F l i g h t Test R e s u l t s O f t h e FlOO EM0 Engine i n an F-15 A i r p l a n e , " A I A A Paper 84-1332, June 1984.
REFERENCES 4Burcham, F. W., Jr., Flyers, L. p., and Walsh, IPutnam, T. W., Burcham, F. W., Jr., A n d r i e s , M.
K. R., " F l i g h t E v a l u a t i o n of a D i g i t a l E l e c t r o n i c G., and K e l l y , J. B., "Performance Improvements o f
E n g i n e c o n t r o l system i n an F-15 A i r p l a n e , " J. of
a H i g h l y I n t e g r a t e d D i g i t a l E l e c t r o n i c C o n t r o l A i r c r a f t , Vol. 22, No. 12, Dec. 1985, pp. 1072-1078.
System f o r an F-15 A i r p l a n e , " NASA TM-86748, 1985.
2 ADECS Development _ _ _ _ ~ _ _ _ _ _ _ _ _ _ _ _ _
ADECS Flight Test _ _ _ _ _ _ _ _ ~ _ _ _ _ _ _ _ _ _
3 Trajec!wy Guidznce Deve!opment
Trajectory Guidance Flight Test _ _ _ _ _
F i g . I . H I D E C program schedule.
I F-15
Horizontal Air Data Indicator Attitude Direction Indicator Modified Flight Digital Flight Actuators Control Computer System Flight Control Sensors
a Added equipment
A N A S A lurnlshed
Moditled equipment A PgWA furnished
F i g . 2 . H I D E C ADECS avionics architecture.
SOFTWARE AMI EXCITER IN DFCC FUNCTIONALLY SIMILAR TO EXISTING F-15 AND FIA-18 HARDWARE FLUTTER EXCITERS PITCH AXIS ONLY (CO‘LLECTIVE STABILATORS) (0.5 TO 20 Hz) FREQUENCY SWEEP AND DWELL TESTS CONTROLLED BY PILOT DFCC HIDEC SOFTWARE AMI EXCITER MODULE LIMITED CAS COMMAND TO SERIES SERVOS PILOT 1 1 0 - AMI CONTROL LOGIC FADE-IN CIRCUIT AUTOMATIC DISENGAGE AMPLITUDE MENU SELECT LOGIC LIMIT EXCITATION OPTIONS: !
i =A(w).K.SINwt K = SCALE
AkR FREQUENCY -
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.
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F i g . 6 . Adaptive ens.ine control system, subsonic EPR u p t r h .
.
Displays INSlADC cc NCI Bus HIDEC.
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Control Panel c PASCOT DEEC I O n l o f t 4 - EngineslBUC A PLA Engine Select Serial Data Bus Mode Select I553
-
Upfront Panel Warning Lights Mode Lights Couple Lights DFCC Flight Control Stick Coupling Uplink Instrumentalion c Computer Computer Cockpit Mechanical Throttle Mechanical Control Flight Control Position Control Couple Command Switch H I D E system architecture, ADECS modes.
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I I
ADECS Control Law BIT/IFIM/Salety BIT/IFIM/Safety and HIOEC "On" Commands Flight Control Flight Control Flight Control
. I
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G I I l D U l 5 I F i g . 8. ADECS architecture.
E Couple Command CoupblUncouple A - E - C - D - MOlMlltlry E - 3 PosRmn, Return to Center F - Momentary Pushbutton H I D E C c r w s t a t i o n orientation.
F i g . 9 .
a MUX bus
- Analog hardwlred
Flight Control Sonwan Test Display NCI Laboratory Facility Central DFCC Computer
-
Flight Control Ta,b. Mach lamb Mach NCI Data HIDEC AEPR, A W a , AFTiT, Wrap ADECS Engine - Control Laws (MUX Interface) DEEC Model Serial
I I
O n / O f l , Mode Select A Control Panel
T I
I I I pq Frud I I I : T I
Console (Hardware) Aircraft Motion Variables Horizontal. Rudder Positions
I
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oP.1oml I F i g . 10. H I D E C labomtory integration t e s t i n g , ADECS mode.
Flight Control Aircraft Model H009 Laws Commands 10 Horizontal Tail. Rudder Actuators
I I
0111010,1 F i g . 11. H I D E C manned simulation t e s t i n g , ADECS mode.
.
2. Gormnmemt Accession No.
3. Recipient's cltrlog No.
1. Report No.
NASA TM-86793 5. Report Date 4. Title md Subtitle H i g h l y I n t e g r a t e d D i g i t a l E l e c t r o n i c C o n t r o l - March 1987 D i g i t a l F l i g h t Control , A i r c r a f t Model I d e n t i f i c a t i o n , 6. Performing Organization Coda and A d a p t i v e Engine C o n t r o l 8. Performing Organization Report No.
7. Author(s) H-1318 J e n n i f e r L. Baer-Riedhart, NASA Ames-Dryden F l i g h t Research F a c i l i t y , and Robert J. Landy o f McDonnell A i r c r a f t Company, 10. Work Unit No.
S t . Louis. M i s s o u r i 9. Performing Organization Nmm a d Address RTOP 533-02-21 NASA Ames Research Center 11. Contract or Gnnt No.
Dryden F1 i g h t Research F a c i 1 i t y P.O. Box 273 . _. -
Edwards , CA 93523-5000
13. T y w of Report 8nd Period C o v r d T e c h n i c a l Memorandum 2. Spotnoring Agency N J ~ urd Addreu N a t i o n a l Aeronautics and Space A d m i n f s t r a t i e n 14. SpMIuwlng Agency Coda Washington, DC 20546 I 5. Supplementary Notes Prepared as A I A A Paper 85-1877 f o r p r e s e n t a t i o n a t t h e A I A A Guidance and C o n t r o l Conference, Snowmass , Colorado, August 19-21. 1985.
6. Abstract The h i g h l y i n t e g r a t e d d i g i t a l e l e c t r o n i c c o n t r o l (HIDEC) program a t NASA Ames Research Center, Dryden F l i g h t Research F a c i l i t y i s a m u l t i p h a s e f l i g h t r e s e a r c h program t o q u a n t i f y t h e b e n e f i t s o f p r o m i s i n g i n t e g r a t e d c o n t r o l systems. McDonnell A i r c r a f t Company i s t h e p r i m e c o n t r a c t o r , w i t h U n i t e d Technologies P r a t t & Whitney A i r c r a f t , and Lear S i e g l e r I n c o r p o r a t e d as m a j o r s u b c o n t r a c t o r s .
The NASA F-15A t e s t b e d a i r c r a f t was m o d i f i e d f o r t h e HIDEC program by i n s t a l l i n g a d i g i t a l e l e c t r o n i c f l i g h t c o n t r o l system (DEFCS) and r e p l a c i n g t h e s t a n d a r d FlOO (Arab 3 ) engines w i t h FlOO e n g i n e model d e r i v a t i v e (EMD) engines equipped w i t h d i g i - t a l e l e c t r o n i c e n g i n e c o n t r o l s (DEEC), and i n t e g r a t i n g t h e DEEC's and DEFCS. The m o d i f i e d a i r c r a f t p r o v i d e s t h e c a p a b i l i t y f o r t e s t i n g many i n t e g r a t e d c o n t r o l modes i n v o l v i n g t h e f l i g h t c o n t r o l s , e n g i n e c o n t r o l s , and i n l e t c o n t r o l s .
T h i s paper focuses on t h e f i r s t two phases o f t h e HIOEC program, w h i c h a r e t h e d i g i t a l f l i g h t c o n t r o l s y s t e m l a i r c r a f t model i d e n t i f i c a t i o n (DEFCS/AMI) phase and t h e a d a p t i v e engine c o n t r o l system (ADECS) phase.
18. Distribution Statement 7. Key Words (Suggested by Authorb)) A d a p t i v e engine s t a l l margin; advanced FlOO U n c l a s s i f i e d - U n l i m i t e d e n g i n e ; d i g i t a l e l e c t r o n i c engine c o n t r o l (OEEC); F-15 a i r c r a f t ; f l i g h t t e s t ; f l i g h t - p a t h management; increased t h r u s t ; improved o p e r a b i l i t y ; i n t e g r a t e d c o n t r o l ; 22. Rice' ' this pagd 21: NO. of p q p ~ 20. Security Clamif.
19. Security Classif. (of this report) Unc 1 ass i f i ed Uncl a s s i f i ed 1 4 A 02