A MICROPROCESSOR BASED SYSTEM FOR W I N D TUNNEL MEASUREMENTS

C. Ravikumar, lbl. B a l a k r i s h n a n a n d V . S . Hol la

Depar tment of Aeroepaco E n g i n e e r i n g I n d i a n I n s t i t u t e o f S c i e n c e , B a n g a l a r e , I n d i a .

b b a t r a c t :

A 1 6- b i t m i c o p r o c e s s o r based s y s t e m h a s been d e s i g n e d and deve loped f o r a u t o m a t i c f l o w f i e l d p r e s s u r e s u r v e y and f o r c e measurements i n t h e low speed wind t u n n e l a t t h e I n d i a n I s t i t u t e of S c i e n c e . The i n s t r u m e n t a t i o n sub sys tems t h a t a r e r e q u i r e d f o r t h e above measurements u n d e r t h e p r o c e s s o r c o n t r o l , t h e sys tem p r o c e s s o r u n i t , i n t e r f a c e s t o s t a n d a r d p e r i p h e r a l s , f u t u r e e x p a n s i o n p r o v i s i o n s a n d communicat ion c h a n n e l t o o t h e r compute r sys tems have a l l been d e v e l o p e d in- house . S o f t w a r e h a s been d e s i g n e d t o p r o v i d e a p o w e r f u l f r i e n d l y a n d r e c o n f i g u r a b l e i n t e g r a t e d i n s t r u - m e n t a t i o n . The s o f t w a r e a l s o e n s u r e s q e a l t ime d a t a a c q u i s i o n , o n- l i n e 'pre- p r o c e s t l i n g and s t o r a g e o f t h e d a t a on a f l o p p y . S o f t w a r e h a s a l s o been d e v e l o p e d on a n i n e x p e n s i v e PC f o r t h e d a t a p r e s e n t a t i o n i n c o l o r g r a p h i c s . The d e s i g n , development and i m p l e m e n t a t i o n d e t a i l s , o f t h e syatem have been p r e s e n t e d l a thie p a p e r .

X n t r o d u c t i o n :

The c l o s e d c i r c u i t wind t u n n e l (CCWT) a t t h e d e p a r t m e n t of Aerospace E n g i n e e r i n g , I n d i a n I n s t i t u t e o f S c i e n c e , h a s been e s t a b l i s h e d i n 1947. The t e s t s e c t i o n o f t h e t u n n e l has an e l l i p t i c a l c r o s s - s e c t i o n o f d i m e n s i o n s 7 ' x 5' and i s b e i n g used f o r f l o w f i e l d s u r v e y s , force/moment and p r e s s u r e s u r v e y measurements . Recen t i n s t r u m e n t a t i o n s e t - u p i n c l u d e d a 3-D t r a v e r s e mechanism powered by i n d u c t i o n m o t o r s , p r e s s u r e p r o b e s , manometer banks t o r e a d t h e p r e s s u r e s and a m e c h a n i c a l b a l a n c e f o r f o r c e measurements . The p r o b e t r a v e r s i n g i s done t h r o u g h a s e t o f ON/OFF s w i t c h e s o o n t r o l l e d manua l ly t o move t h e p robe i n t h e r e q u i r e d d i r e c t i o n over a t e s t s e c t ' i o n o f 96" x 48" x 3 6 " . A se t o f m e c h a n i c a l c o u n t e r s a r e u s e d t o i n d i c a t e t h e t r a v e r s e p o s i t i o n . T h i s a r r a n g e m e n t p r o v i d e d a r e s o l u t i o n of 0.0025t1 and 0.1l' o v e r a l l a c c u r a c y i n p robe p o s i t i o n i n . The pre8sure p r o b e used f o r f l o w f i b f d s u r v e y

54-IClASF '87 RECORD

i s a b l u n t e d c o n i c a l n o s e 5 h o l e p r o b e . Both U-tube manometer banks and r e s e r v o i r t y p e manometer banks a r e a v a i l a b l e f o r p r e s s u r e d a t a c o l l e c t i o n . F o r a c c u r a t e p r e s s u r e measurements a s e t of p r o j e c t i o n manometers i n d i g e n e o u s l y deve loped a t t h e d e p a r t m e n t a r e a l s o a v a i l a b l e . T h e s e m a n u a l l y r e a d manometers have a r e s o l u t i o n of 0 . 2 ~ ~ . I n a t y p i c a l t u n n e l r u n , t h e t e s t model i s mounted on t h e m e c h a n i c a l b a l a n c e ' s t r u t s and t h e aerodynamic f o r c e s and moments a r e measured m a n u a l l y by c o u n t e r b a l a n c i n g t h e unknown l o a d s wi th dead w e i g h t s . Flow f i e l d d a t a i s c o l l e c t e d t h r o u g h t h e p r e s s u r e p r o b e , f i t t e d t o t h e m a n u a l l y o p e r a t e d t r a v e r s e meachanism and a manometer bank o r t h r o u g h a s e t o f 6 p r o j e c t i o n manometers. The p r e s s u r e s u r v e y f rom t h e body t a p p i n g s is made w i t h a manometer bank. For t h e d a t a r e d u c t i o n , t h e g a t h e r e d d a t a i s f i r s t punched on compute r c a r d s and t h e n f e d t o t h e main frame computer DEC sys tem 1090 a t t h e c e n t r a l comput ing f a c i l i t y o f t h e i n s t i t u t e .. System Overview

demand f o r t h e i n s t r u m e n t a t i o n been upgraded

I n o r d e r t o meet t h e i n c r e a s i n g t u n n e l a v a i l a b i l i t y , t h e

Rystem i n t h e t u n n e l have t o au tomate moat o f the

e x p e r i m s n t a l p r o c e d u r e s [ I 1. The imminen t a d v a n t a g e s due' t o t h i e a r e f a t i t e r a n d a c c u r a t e d a t a a c q u i s i t i o n t h a t i s f r e e from human e r r o r s , and r e d u c t i o n i n t o t h e ae rodynamic q u a n t i t i e s , which make t h e system s e l f c o n t a i n e d and improve t h e t u r n a r o u n d time.

The modern t e c h n o l o g y i n t h e f i e l d s o f wind t u n n e l i n s t r u m e n t a t i o n a n d compute r b a s e d s y s t e m s , o f f e r a wide c h o i c e o f i n s t r u m e n a t i o n and programmable c o n t r o l l e r s t o a u t o m a t e a t e s t f a c i l i t y . On t h e i n s t r u m e n a t a t i o n f r o n t , however , f o r most o f t h e small- and medium-range t e s t f a c i l i t i e s , t h e c h o i c e i s l i m i t e d by s e v e r a l f a c t o r s l i k e t h e p r e s e n t c i r c u m s t a n c e s of t h e t u n n e l o p e r a t i o n , , t h e e x h o r b i t a n t c o s t f a c t o r s i n v o l v e d i n t h e i n a t r u m e n t a t i o n and t h e r e q u i r e d

1 1

CX2449-7/87/0000-004 $1.00 @ 1987 UJB

m o d i f i c a t i o n s t o t h e t u n n e l t o accomodat new i n s t r u m e n a t i o n . Due t o such r e a s o n s , t h e i n s t r u m e n t a t i o n i n t h e above t u n n e l h a s been upgraded t o f a c i l i t a t e a u t o m a t i o n i n s t e a d o f a c q u i r i n g modern equipment l i k e l a s e r d o p p l e r v e l o c i m e t e r s , e t c . [Z -81 . T h i s u p g r a d a t i o n work i n c l u d e d t h e d e s i g n and i n t e r f a c e s t o c o n t r o l t h e mechan ica l i n s t r u m e n t s , t h e deve lopment o f a new p r e s s u r e measur ing d e v i c e and tin an t i log DAS. A d i g i t a l i n t e r f a c e h a s been d e s i g n e d and deve loped t o a u t o m a t e t h e 3 - D p r o b e t r a v e r s e o p e r a t i o n . A new 6- c h a n n e l d i g i t a l manometer h a s been d e s i g n e d a n d d e v e l o p e d t o a c q u i r e t h e p r e s s u r e d a t a f rom t h e 5- hole p robe and t h e t u n n e l f r e e stream. T h i s s e n s o r i s based on a u t o m a t i n g t h e p r a s s u r e measurement p r o c e s s o f a c o n v e n t i o n a l U- tube manometer u n d e r t h e c o n t r o l o f a m i c r o p r o c e s s o r . I n s t r u m e n t s l i k e s c a n i v a l v e o r a n ESOP [ 7 1 would a l s o c l a i m a p l a c e i n such a n a p p l i c a t i o n . However, t h e a b i l i t y t o r e a d a c c u r a t e l y all t h e 6 c h a n n e l s s i m u l t a n e o u s l y o v e r a wide dynamic r a n g e , and t h e r e l a t i v e l y low c o s t makes i t a more s u i t a b l e one f o r t h e p r e s e n t

To f a c i l i t a t e t h e a u t o m a t i c c o n t r o l o f t h e model a t t i t u d e , a new model mount ing r i g h a s been i n s t a l l e d . The model mount ing r i g d e s i g n e d and deva loped by a n o t h e r g r o u p i n t h e d e p a r t b e n t p r o v i d e s t h e model c o n t r o l i n t h e d i r e c t i o n s of p i t c h and yaw. F o r a c c u r a t e force measurements , as a n obv ious c h o i c e , a 6-component s t r a i n gauge b a l a n c e h a s been a c q u i r e d . The p r e s e n t and t h e f u t u r e e x p e r i m e n t a l n e e d s a t t h e CCWT d i c t a t e t h a t t h e d a t a f rom t h e s t r a i n g a u g e b a l a n c e be a c q u i r e d a t a 1 KHz s a m p l i n g r a t e and a r e s o l u t i o n o f a t l e a s t 12-b l t t l . In view o f t h i s and t h e p o s s i b l e f u t u r e e x p a n s i o n s , a 32-channe1, 1 2 - b i t d a t a a c q u i s i t i o n sys tem (DAS) h a s i been i n c l u d e d .

8 p p l i C a t i O n .

I n o r d e r t o c a t e r t o t h e needs o f p r e s s u r e p l o t t i n g e x p e r i m e n t s and wake p r e s s u r e s u r v e y s , a 48 p o r t s c a n i v a l v e v i t h a n LVDT t y p e p r e s s u r e s e n s o r h a s also been i n c l u d e d i n t h e sys tem. The LVDT o u t p u t i a a c q u i r e d by t h e DAS.

The t a s k of a u t o m a t i n g t h e e x p e r i m e n t a l p r o c e d u r e s c o u l d be e f f e c t e d by i n t e g r a t i n g t h e above i n d i v i d u a l s u b a y s t e m s w i t h a n a p p r o p r i a t e l y s e l e c t e d programmable c o n t r o l l e r a n d DAS f r o v t h e s e v e r a l h i g h p e r f o r m a n c e , commerb ia l ly a v a i l a b l e , o f f - t h e s h e l f compute r b a s e d s y s t e m s . For example , s y s t e m s l i k e MACSYM, m a n u f a c t u r e d by Analog D e v i c e s , U.S.A. o r DATA TRANSLATE ( D a t a T r a n s l a t e C o r p o r a t i o n , U . S . A . ) [91 e t c . , o f f e r h i g h pe r fo rmance s p e c i f i c a t i o n s and a t t r a c t i v e c a p a b i l i t i 6 s . However, most o f t h e s e modules are o f g e n e r a l p u r p o s e n a t u r e .

e B e s i d e s , t h e r e q u i r e m e n t s i n a wind t u n n e l c a l l f o r s e v e r a l s p e c i a l i s e d a c q u i s i t i o n and c o n t r o l f u n c t i o n s t h a t c o u l d n o t be met e a s i l y by t h e commercia l ly a v a i l a b l e sys tems . For example, t h e i n t e r f a c e s t o t h e 3-D t r a v e r s e mechanism and t h e d i g i t a l manometer a r e t o o s p e c i f i c t o wind t u n n e l a p p l i c a t i o n s . Commercial sys tems g e n e r a l l y do n o t meet t h e s e r e q u i r e m e n t s and o f t e n r e q u i r e e x t e n s i v e t c t i l u r i n g , i f c h o s e n .

A l t e r n a t i v e l y , t h e above t a s k can be implemented by d e s i g n i n g a d e d i c a t e d c o s t e f f e c t i v e system p r o c e s s o r u s i n g t h e e a s i l y a v a i l a b l e advanced m i c r o p r o c e u s o r s . A 1 6- b i t m i c r o p r o c e s s o r system has been d e s i g n e d a n d deve loped t o meet t h e s e r e q u i r e m e n t s . The p r e s e n t c o n f i g u r a t i o n of t h e system i n c l u d e s a CRT t e rmina l f o r usor i n t e r a c t i o n , an i n t e r f a c e t o s t a n d a r d p r i n t e r s f o r h a r d copy o u t p u t s , a MULTIBUS i n t e r f a c e f o r any f u t u r e w p u n s i o n s and t\ f l o p p y d i s c c o n t r o l l e r f o r d a t a a t o r a g e . The b l o c k d iagram of t h e s y s t e m c o n f i g u r a t i o n i s g i v e n i n F i g u r e 1 .

P o w e r f u l hardware w i l l be o f l i t t l e u s e w i t h o u t a p p r o p r i a t e s o f t w a r e . I n many a p p l i c a t i o n s t h e s o f t w a r e deve lopment b e a r s a d i r e c t r e l a t i o n s h i p w i t h t h e a v a i l a b l e ha rdware . T h i s o f t e n l e a d s t o a s i t u a t , i o n wherein an i n t e g r a t e d a p p r o a c h t h a t c a t e r s , w i t h e q u a l emphas i s t o b o t h h a r d w a r e a n d s o f t w a r e a s p e c t s would be needed f o r a s u c c e s s f u l d e s i g n e x e r c i s e .

The s o f t w a r e duvtiloped i n assembly l a n g u a g e i n i t i a l i z e s t h o p e r i p h e r a l I/O c h i p s and t h e i n t e r f a c e s t o t h e i n s t r u m e n t s . The s o f t w a r e f o r u s e r i n t e r a c t i o n , p r o v i d e s a f r i e n d l y env i ronment f o r t h e user. In t h e s e t - u p mode, a s e t of prompt and h e l p messages a l l o w s t h e user t o e a s i l y c o n f i g u r e t h e i n s t r u m e n t s t o t h e s pe c i f i c exp e r i m en tal. n e e d s . The s o f t w a r e t o c o n t r o l t h e e x p e r i m e n t h a s been des igned ts s e q u e n c e t h e c o n t r o l o p e r a t i o n s th rough t h e d r i v e r r o u t i n e s f o r , each o f t h e i n t e r f a c e s , a c q u i r e t h e dn'ta i n r e a l t ime and p r o c e a s i t o n- l i n e . The p r o c e s s e d d a t a i 6 e i t h e r p r i n t e d o r s t o r e d on a f l o p p y i n t h e IBM f o r m a t . The d a t a on t h e f l o p p y c a n a l s o be t r a n s f e r r e d t o t h e mainframe compute r DEC 1090 f o r d e t a i l e d a n a l y s i s , i f needed.

The data p r e s e n t a t i o n i n an e a s y t o i n t e r p r e t fo rm, i s also a n i m p o r t a n t a s p e c t of an i n t e g r a t e d system. The c o l o r coded g r p h i c s t e c h n i u8 deve loped by Winkleman e t . a l . I l O C f , i s a v e r y u q e f u l t o o l f o r f l o w f i e l d v i s u a l i s a t i o n and i n t e r p r e t a t i o n , But as i t r e q u i r s s s o p h i s t i c a t e d computer systems a n d image p r o c e s s i n g s y s t e m s i t becomes u n a f f o r d a b l e f o r s m a l l s c a l e sys tems . However f o r t h u p r e s e n t s y a t e n , g r a p h i c 8 s o f t w a r e has b e e s d e v e l o p e d on a n IBM PC c o m p a t i b l e machine, t o p r e s e n t t h e p r o c e s s e d d a t a in c o l d r

I

ICIASF '17 HL;COHL)-SS

g r a p h i c s con tour p l o t s and v e l o c i t y v e c t o r p l o t s . The package e x p l o i t s t h e c a p a b i l i t i e s of t h e PC and s i m p l i f i e s t h e f low f i e l d a n a l y s i s .

A d e t a i l e d d e s c r i p t i o n o f t h e ha rdware and s o f t w a r e f o r t h e u s e r i n t e r a c t i o n , o v e r a l l e x p e r i m e n t a u t o m a t i o n and d a t a p r e s e n t a t i o n is givun below.

System P r o c e s s o r U n i t :

The b lock d iagram of t h e sys tem p r o c e s s o r u n i t h a s been shown i n F i g u r e 2 . The h e a r t %f t h i s u n i t i s a 1 6- b i t m i c r o p r o c e s s o r a n d numer ic d a t a p r o c e s s o r p a i r , 8086-8087. The 8086, a t h i r d g e n e r a t i o n m i c r o p r o c e s s o r , is c a p a b l e of a d d r e s s i n g u p t o IMb 1113. I t o p e r a t e s on and t r a n s f e r s 1 6 b i t d a t a a t a t i m e . The i n c l u s i o n of 8087 i n t h e d e s i g n * i m p r o v e s t h e p r o c e s s i n g s p e e d phenomena l ly . B e s i d e s , t h e 8087's i n h e r e n t c a p a b i l i t i e s t o o p e r a t e w i t h 8 0 b i t words , p r o v i d e h i g h e r a c c u r a c y . T h e u n i t h a s been d e e i g n e d t o accommodtite t h e n e c e s s a r y memory and o t h e r programmable p e r i p h e r a l c h i p s t o i n t e r f a c e t h e s u b s y s t e m s . N o t a b l e amongest them a r e -

a Programmable p o r i p h o r a l t i m o r s ( I n t e l 825.3) - t o lt,.t.mv utuinp' ~ t i c i I t o q u i k i J d d a t a titid t o g e n e r a t e t l n i r i r I n t e r r u p t s f o r t h e data sampling p u r p a s a s ,

0 Programmable i n t e r r u p t c o n t r o l l e r ( I n t e l 8259) - t o r o c e s s m u l t i p l e i n t e r r u p t 6 ( u p t o 87 from t h e sub- syiit'Fm niodulev and t i n i e r i n t . e r r u p t 3 and draw t o t h e a t t e n t i o n o f t h e p r o c e s s o r when r e q u i r e d (121.

0 U n i v e r s a l synchron ous and a 3 y n c h r on o u s t r a n s m i t t e r / r e c e i v e r Y ( I n t e l 8251) - t o s u p p o r t a C R T t e r m i n a l f o r u s e r i n t e r f a c e , and t o p r o v i d e a programmable a u x i l i a r y RS- 232C communicat ion c h a n n e l [I31 f o r l i n k i n g t h e sys tem t o o t h e r compute r s (a PC h a s been c o n n e c t e d t o t h i s c h a n n e l ) .

A MULTIBUS i n t e r f a c e - t o f a c i l i t a t e any f u t u r e e x p a n s i o n s ( u p t o 6 ) .

F u t u r e e x p a n s i o n p r o v i s i o n s have been s i m p l i f i e d by d e s i g n i n g a MULTIBUS i n t e r f ace t o t h e p r e s e n t sys tem [ 14 ,151 . The bus s t r u c t u r e p r o v i d e s a common e l e m e n t f o r communicat ion between a w i d e v a r i e t y o f sys tem modules which i n c l u d e memory, d i g i t a l and a n a l o g I/O e x p a n s i o n b o a r d s and p e r i p h e r a l c o n t r o l l e r s . It c o m p r i s e s o f 20 d a t a l i n e s ( e q u i v a l e n t t o a n a d d r e s s s p a c e o f 1 Mb,), 1 6 b i - d i r e c t i o n a l d a t a l i n e s , 8 m u l t i l e v e l i n t e r r u p t l i n e s and s e v e r a l bus c o n t r o l ,

t i m i n g and power s u p p l y l i n e s . Modules t h a t U Y ~ t h e MULTIBUS h a v e a m a s t e r - s l a v e r e l a t i o n s h i p . The system p r o c e s s o r , which i s t h e bus m a s t e r , d r i v e s t h e command a n d a d d r e s s l i n e s and c o n t r o l s t h e b u s . The p r c o a n t d e s i g n p r o v i d e s s i x a l o t , a for t h o s l a v e u n i t s , o u t of which t h e f i r s t s l o t h a s been used f o r t h e 32 c h a n n e l a n a l o g d a t a a c q u i s i t i o n s y s t e m . A f l o p p y d i s c c o n t r o l l e r has buun u u u d i n the s u a o n d s l o t .

3- D T r a v e r s e Automat ion :

T r a v e r s e mechanisms may employ e i t h e r stepper motors o r i n d u c t i o u niotars . One of t h e i m p o r t a n t f a c t o r s t h a t i n f l u e n c e t h e c h o i c e o f motors i s t h e c a r r i a g e l o a d . S t e p p e r m o t o r s a r e s u i t a b l e f o r d r i v i n g l i g h t c a r r i a g e s . B u t u o s t o f t e n t h e c a r r i a g e w e i g h t e n c o u n t e r e d i n ti t y p i c a l medium and l a r g e s i z e wind t u n n e l s e t u p i s c o n s i d e r a b l y more. I n such s i t u a t i o n s i n d u c t i o n m o t o r s a r e p r e f e r r e d t o s t e p p e r m o t o r s . S e v e r a l i n t e r e s t i n g p o s s i b i l i t i e s do e x i s t for a u t o m a t i n g t h e probe t r a v e r s e mechanism employ ing i n d u c t i o n motors . The t e c h n i q u e employed t o i n t e r f a c e t h e t r a v e r s e mechanism t o t h o 1 6- b i t p r o c e s s o r makes i t s i m p l e r t o p o s i t i o n t h e p r o b e p r e c i s e l y .

'1'11e t 3 ~ ~ ~ v ~ ? t r s t j mechanism dtnployrtd i n t h a C C l i T h a s t h r e e n o t o r s t o move t h e p robe 9ott a l o n g t h e f l o w d i r e c t i o n (X- d i r e c t i o n ) , 48" a l o n g t h e l a t e r a l d i r e c t i o n ( Y- d i r e c t i o n ) and 12" i n v e r t i c a l d i r e c t i o n ( 2 - d i r e c t i o n ) . I n o r d e r t o k e e p t h e t r a v e r s e mechanism ups t ream e f f e c t s t o a minimum, t h e movement o f t h e c a r r i a g e i n t h e Z- d i r e c t i o n i s l i m i t e d t o 1 ' . To c o v e r t h e c o m p l e t e 2 - d i r e c t i o n t h e p r o b e h o l d e r r o d c a n be changed t o e x t e n d t h e p r o b e movement downwards.

Automat ing t h e above t r a v e r s e mechanism u s i p g t h e m i c r o p r o c e s s o r i n v o l v e s :

( i ) P robe d i s p l a c e m e n t s e n s i n g o v e r a maximum d i s t a n c e o f 96 i n c h e s .

(ii) C o n t r o l l i n g t h e t h r e e motors t o move t h e p r o b e t o t h e r e q u i r e d p o s i t i o n In a l l t h e t h r e e d i r e c t i o n s

(iii) C a r r i a g e l i m i t s e n s i n g a t e i t h e r ends o f e a c h o f t h e three d i r e c t i o n s , and

S o f t w a r e f a r e a s y programming o f t h e ( i v ) module

One o f t h e w e l l known and a c c u r a t e methods f o r p o s i t i o n s e n s i n g i s by u s i n g t h e Gray code s c a l e . But c o n s i d e r i n g t h e

. . I

+ % I

56-ICIASF '87 RECORD

s p a n o f t h e p r e s e n t s y s t e m , a 0.01" r e s o l u t i o n w i l l need a 1 4 - b i t Grey code s c a l e . Due t o t h e o b v i o u s d i f f i c u l t i e s i n v o l v e d i n f a b r i c a t i n g a 1 4 - b i t Gray code s c a l e w i t h O.O1ll l i n e s , o f t e n a p o t e n t i o m e t r i c method i s u s e d f o r p o s i t i o n s e n s i n g [ 1 6 ] . However, i n t h e p r e s e n t s y s t e m , i n o r d e r t o a d h e r e t o t h e s i m p l i s t i c d e s i g n g o a l , a n a l t e r n a t e method h a s been d e v e l o p e d . I n t h i s method, p r o v i s i o n s h a v e b e e n made t o counL t h e number o f r e v o l u t i o n s o f t h e l e a d s c r e w o f e a c h moto r w i t h t h e r e q u i r e d r e s o l u t i o n , u s i n g I R o p t i c a l s e n s o r s , MCT- 8 [ 1 7 ] . The number o f r e v o l u t i o n s a r e c o u n t e d u s i n g a s o f t w a r e programmable i n t e r v a l t i m e r (8253) i n t e r f a c e d t o t h e p r o c e s s o r . This a v o i d s t h e p r o b l e m s assoc la t t rd w i t h t h o t i nu log toohniquas. To c o n t r o l t h e 3 m o t o r s , a b i d i r e c t i o n a l mo to r c o n t r o l c i r c u i t r y i s d e s i g n e d u s i n g a s i m p l e l o g i c c i r c u i t a n d r e l a y s . I n o r d e r t o s a f e g u a r d t h e m o t o r s a g a i n s t t h e p rogram and human q r r o r s , f e a t u r e s l i k e , c a r r i a g e l i m i t s e n s i n g , a u t o- m o t o r OFF and i n t e r r u p t t o t h e p r o c e s s o r a r e i n c o r p o r a t e d i n t h e d e s i g n . The e l e c t r o n i c i n t e r f a c e i s shown i n t h e F i g u r e 3 .

The s o f t w a r e f o r t h i s i n t e r f a c e f a c i l i t a t e s c a l i b r a r t i o n o f t h e t r a v e r s e a n d f o r m s a l o o k- u p t a b l e f o r 4 t h e c a l i b r a t i o n c o n s t a n t s . T h i s c a l i b r b t i o n c o m p e n s a t e s f o r t h e e r r o r s d u o t o t h e i n e r t i a o f t h e i n d u c L i o n m o t o r s , m e c h a n i c a l g e a r s a n d a l s o t h e m i s a l i g n m e n t e r r o r s i n e a c h a x i s .

F o r p r o b e p o s i t i o n c o n t r o l t h e s o f t w a r e a l l o w s t h e u s e r t o d e f i n e t h e s c a n volume i n t h e t e s t s e c t i o n a n d o t h e r p a r a m e t e r s . The f e a t u r e s o f f e r e d by t h i s a o f t w g r e i n c l u d e -

P r o b e movement M A N U A L / A U T O M A T I C s e l e c t i o n s .

d i r e c t i o n s . e Scan limits on e a c h o f t h e t h r e e

I, Number o f s e g m e n t s w i t h i n t h e l i m i t s i n e a c h d i r e c t i o n .

D i f f e r e n t g r i d s i z e s f o r d i f f e r e n t s e g m e n t s w i t h i n t h e s c a n l imits .

O t h e r o p t i o n s i n c l u d e

I, D e f a u l t g r i d s e l e c t i o n .

G r i d s i z e d y n a m i c a l l y a l t e k a b l e w i t h o u t d i s c o n t i n u i n g t h e e x p e r i m e n t .

a C a l i b r a t i o n and f o r m i n g a new l o o k- u p t a b l e f o r t h e c o r r e c t i o n t e r m s t o

6- Channel D i g i t a l Manometer :

The i n s t r u m e n t is based o n d i g i t a l r e n d i n g o f t h e d i s t a n c e between t h e l i q u i d l e v e l s i n a U-tube manometer by m e c h a n i c a l l y t r a v e r s i n g a c a r r i a g e t o w h i c h a r e f i x e d a p a i r o f l i q u i d l e v e l s e n s o r s . The c a r r i a g e t r a v e r s e i s s e n s e d by a d i s t a n c e s e n s o r which p r o d u c e s a p u l s e p e r O . l m m movement o f t h e c a r r i a g e . T h e s e p u l s e s a r e c o u n t e d by a f r e e r u n n i n g c o u n t e r . The m i c r o p r o c e s s o r r e a d s t h e l e v e l s e n s o r s ' s t a t u s and a t t h e i n s t a n t s o f t h e c a r r i a g e c r o s s i n g t h e l i q u i d l e v e l m e n i s c u s , s a m p l e s t h e f r e e r u n n i n g c o u n t e r . The r e a d i n g s a r e s t o r e d i n t h e s y s t e m memory. Once t h e s e r e a d i n g s a r e t a k e n f o r a l l t h e c h a n n e l s , t h e d i f f e r e n c e in ruadingu fLJr each o f t h u nilrnornetora i e computed by t h e m i c r o p r o c e s s o r a n d t h e d a t a i s a v a i l a b l e f o r p r i n t i n g o r any f u r t h e r p r o c e s s i n g .

A s e m i a u t o n i a t i c v e r s i o n o f t h i s i n s t r u m e n t , i n wh ich T T L h a r d w a r e h a s b e e n u s e d t o r e a d t h e l i q u i d column h e i g h t in a U- tube h a s b e e n d e v e l o p e d i n t h e d e p a r t m e n t o f A e r o s p a c e E n g i n e e r i n g , I I S c [ I 81. However, i n t h i s p r o t o t y p e i n s t r u m e n t , t h e motor c o n t o l i s m a n u a l a n d a cam mechanism i s used f o r t h e c a r r i a g e movement. I n v i ew o f t h e r e l a t i v e l y l a r g e r a n g e o f movement r e q u i r e d f o r t h e p r e s e n t i n s t r u m e n t , t h e m e c h a n i c a l d e s i g n o f t h i s p r o t o t y p e h a s been changed c o n s i d e r a b l y i n t h e new I n s t r u m e n t t o f a c i l i t a t e r e l i a b l e o p e r a t i o n u n d e r t h e c o n t r o l o f t h e m i c r p r o c e s s o r .

T h e m a c h a n i c a l c o n s t r u c t i o n a n d t h e e l e c t r o n i c s i n t e r f a c e t o t h e p r o c e s s o r h a v e been shown i n t h e F i g u r e s 4 1791. The l e n s e e f f e c t o f a g l a s i i t u b e f i l l e d w i t h a l c o h o l i s c o n v e n i e n t l y made u s e o f , t o s e n s e t h e l i q u i d l e v e l u s i n g I R o p t i c a l s e n s o r s (MCT-8). The d i s t a n c e t r a v e r s e by t h e c a r r i a g e i s s e n s e d as a f u n c t i o n o f t h e moto r d r i v e s o t h e r e a d i n g s a r e i n d e p e n d e n t 04 t h e motor s p e e d v a r i a t i o n s . A l t h o u g h t h e p r e s e n t d e s i g n i n c l u d e s o n l y 6 - c h a n n e l s , w i t h minor e x t e n s i o n s , t h e i n t e r f a c e c a n be implemented f o r a s many c h a n n e l s a s r e q u i r e d w i t h a s u i t a b l e m e c h a n i c a l s e t - u p .

The r e s o l u t i o n o f t h e s y s t e m i s O . l m m of l i q u i d column. With t h e p r e s e n t mechan i sm, i t may be n o t e d t h a t t h e a c c u r a c y o f t h e r e a d i n g s i s i n d e p e n d e n t of t h e s p e e d v a r i a t i o n s o f t h e m o t o r . T h i s e l i m i n a t e s t h a need f o r a p r e c i s i o n m o t o r a n d s p e e d c o n t r o l c i r c u i t r y . The a c c u r a c y o f t h e u n i t i s f o u n d t o be b e t t e r t h a n 0.2mm. The r a n g e o f t h e i n s t r u m e n t is +1000mm. The p r e s e n t d e s i ne r e q u i r e s 2 . 5 s e c t o a c q u i r e one s e t o f s a m p l e s .

.. .. . , . ?

ICLASF '87 HECOKD-57

I n e t r u m u n t a t i o n f o r Force Moasurumente and Preasure 3urvey0 ;

F o r c e meaaurement i n s t r u m e n t a t i o n h a s buan implemuntud t h r o u g h CI u t r i i i ng:’*ugu

p o s i t i o n encoder and a motor c o n t r o l i n t e r f a c e h a s been d e s i g n e d t o c o n t r o l t h e model on t h e new mounting r i g d e s i g n e d by a s e p a r a t e group [ r C O l .

A 48- por t s c a n i v a l v e h a s been i n t e r f a c e d t o t h e s y s t e m p r o c e s s o r a s a p a r t of t h e p r e s s u r e s u r v e y i n s t r u m e n t a t i o n .

b a l a n c e and a 32-channe l a n a l o g UAS. A

6-Component S t r a i n Gauge B a l a n c e :

For a c c u r a t e f o r c e measurements , 6 component s t r a i n g a u g e b a l a n c e h a s been a c q u i r e d . It h a s e i g h t s t r a i n gauge b r i d g e s t o i n d i c a t e a l l t h e s i x components of fo rce /moments . These e i g h t s t r a i n gauges p r o v i d e e l e c t r i c a l s i g n a l s i n t h e r a n g e o f 22 rnv f u l l s c a l e w i t h e x c i t r r t i o n v o l t a g e o f 4 V d c . T h e s t r a i n g a u g e b a l a n c e h a s been c a l i b r a t e d f o r use i n t h e p r e s e n t sys tem [213.

32-Channel Data A c q u i s i t i o n System :

The 32- channe l d a t a n c q u i s i t f o n s y s tern ( e x p a n d a b l e t o 256 c h a n n e l s ) h a s been shown i n F i g . . .. It c o n s i s t s o f 8 c h a n n e l p r e a m p l i f i e r s which a r e t a i l o r e d t o r e a d t h e s i g n a l s from t h e s t r a i n gauge b a l a n c e , a 32 c h a n n e l m u l t i p l e x e r , a g a i n s e l e c t a b l e i n s t r u m e n t a t i o n a m p l i f i e r , a sample and h o l d c i r c u i t and a b u f f e r e d 12- b i t s u c c e s v i v e a p p r o x i m a t i o n a n a l o g t o d i g i t a l “ c o n v e r t e r . The t i m i n g s i g n a l s t o s e q u e n c e t h e o p e r a t i o n o f t h e s e b l o c k s have been p r o v i d e d by a c o n t r o l l e r c i r c u i t r y . T h i s module i s c o n f i g u r e d f o r memory mapped I / O and t h e a d d r e s s is jumper s e l e c t a b l e . The module h a s bean i n t e r f a c e d t o t h e s y s t e m p r o c e s s o r t h r o u g h i t s MULTIBUS. The b l o c k diagram o f t h e DAS is g i v e n i n F i g u r e 5.

Expansiori u p t o 256 c h a n n e l s may be e f f e c t e d by u t i l i z i n g t h e expander ’

c i r c u i t r y w i t h minimum a d d i t i o n a l ha rdware o f p r e a m p l i f i e r s and m u l t i p l e x e r s . O t h e r h a r d u a r e f e a t u r e s i n c l u d e s i g n a l c o n d i t i o n i n g a t t h e i n p u t end i n t h e s h a p e o f ha rdware l ow p a s s f i l t t i r s , nnd i n p u t o v e r v o l t a g e p r o t e c t i o n . I n i t s c p n f i g u r a t i o n , t h e 8 l o w i n p u t c h a n e e l s a c c e p t i n p u t s i n t h e r a n g e o f 2 2mv w h i l e t h e h i g h l e v e l i n p u t s ~ ~ l l o w i n p u t s o f +5v f u l l s c a l e . The s e t t l i n g t i m e s o f e z c h component p u t t o g e t h e r w i l l amount t o 38 u a e c when t h e o v e r a l l a m p l i f i e r g a i n i s 1 , b u t w i l l i n c r e a s e u p t o 100 u D ~ J C f o r a maximum gtiin o f 1000. These f i g u r e s imply

ri

t h u t :;uolpLiirlC: r * t l t u u u p t u 10 KJIZ Ul‘d

c ti i ev Z I b 1 o w ti i 1 u o p u i-.~ 1. i r i g th v ti III 1) 1 i i’ 1 u r u u t iiiuximiirr guJ.11. ‘The 1 2 bit dt i tu a c q u i s i t i o n s y s t e m p r o v i d e s an o v e r a l l u o c u r t i c y at. 0 .1%. T h i i 3 w o d u l u hus beon w i r e d f o r i n t a r r u p t modu 01’ o p u r u t l O r i i i r t h e s y s t e m .

The a n a l o g d a t a a c q u i s i t i o n s o f t w a r e r r l l aw3 tdhu i IBoc t o o o n f i p u r o t h e module t o t h e s p e c i f i c requiremari t of the e x p e r i m e n t . The c h a n n e l numbers t o be sampled , bounds on i n p u t l e v e l s , s c a n r a t e and number o f samples f o r a v e r a g i n g a r e programmable. The a c c u r a c y o f t h e a c q u i r e d d a t a i s f u r t h e r improved by a u t o m a t i c d r i f t and g a i n e r r o r c a n c e l l a t i o n s . Once t h e module i s d e f i n e d f o r an e x p e r i m e n t , i n o r d e r t o a c q u i r e t h e d a t a , t h e s y s t e m p r o c e s s o r i s s u e s a command t o i n i t i a t e t h e d a t a c o n v e r s i o n . Once t h e d a t a c o n v e r s i o n i s comple te , t h e d a t a a c q u i s i t i o n System w i l l i n t e r r u p t t h e p r o c e s s o r s o t h a t t h e p r o c e s s o r may r e a d t h e c o n v e r t e d d a t a . D u r i n g t h e c o n v e r s i o n t ime, t h e p r o c e s s o r can e i t h e r p r o c e e d w i t h o t h e r t u s k s a s s i g n e d , o r wait for t h e c o n v e r s i o n t o cornplete . T h i a f e a t u r e c o n t r i b u t e s t o f u r t h e r processor t i m e s a v i n g s when t h e module i s used i n t h e t i m e r i n t e r r u p t mode. When t h e d a t a a c q u i s i t i o n i s completct , t h e i n p u t l e v e l s on t h e s e l e c t e d c h a n n e l s a r e compared a g a i n s t t h e s e t l i m i t s .

S c a n i v a l v s Pressure Measurement System :

P r e s s u r e s u r v e y expur lments a t t h e CCWT r e q u i r e m u l t i p l e p r e s s u r e measurement from a r a k e o f p i t o t t u b e s t r a v e r s e d i n a v e r t i c a l p l a n e , i n t h e wake o f the m o d e l , o r from t h e t a p p i n g s drawn from t h e modo l s u r f a c e . I n t h e sys tem, a 48-port s c a n i v a l v e (model 4Sd3) e n a b l e s t h e s e measurements t o be made u s i n g a s i n g l e p r e s s u r e t r a n s d u c e r . F i g u r e 6 shows t h e b l o c k diagram o f t h e e l e c t r o n i c i n t e r f a c e t o t h e s y s t e m p r o c e s s o r . I n o r d e r t o o b t a i n t h e por t ‘ .numbers p r e c i s e l y , a 6-bit o p t i c a l s h a f t p o s i t i o n Gray e n c o d e r h a s been used on t h e s c a n i v a l v e motor s h a f t . O p t i c a l Gray e n c o d e r h a s been d e s i g n e d u s i n g s i x s e t s of I R emit ter and s e n s o r p a i r s ( M C T - 8 ) mounted a c r o s s an o p t i c a l c i r c u l a r Gray code d i s c . The Gray c o d e p a t t e r n on t h e d i s c w i t h 48 l e v e l s , has been made u s i n g ‘a c o o r d i n a t o- g r a p h t o e n s u r e h i g h p r e c i s i o n , A b i - d i r e c t i o n a l motor d r i v e c i r c u i t r y htls been d e s i g n e d and d e v e l o p e d ( u s i n g t r a n s i s t o r s ) t o c o n t r o l t h e s c a n i v a l v e motor o p e r a t i o n . Based on t h e d i r e c t i o n arid ON/OFF i n p u c s t o t h i s b l o c k , t h e c i r c u i t d r i v e s t h e motor i n t h e u p p r o p r i a t e d i r e c t i o n , and t h u s p r o v i d e s a random a c c e s s o f 8 p a r t i c u l a r p o r t .

#--ICIASF ‘117 HECOHD

Th B pr i u u in u L I (I 111 u J, L 1 p 1 w x IJ J o u L pu L i d f e d t o a LVDT t y p e p r e s s u r e t r a n s d u c e r which p r o v i d e s a +5v o u t p u t f u l l sca le w i t h a n a c c u r a c y o f 0 .1% o v e r a r a n g e of 0 t o 0.1 p s i . Channel 10 o f t h e oarliur d e s c r i b e d d a t a a c q u i u i t i o n s y Y tem h a s be en used t o r e a d t h e a n a l o g o u t p u t o f t h i s t r a n s d u c e r . As a r e s u l t , a l t h o u g h t h e s a m p l i n g r a t e on e a c h c h a n n e l o f t h e d a t a a c q u i s i t i o n aystem is u p t o 10 KHz, t h e s a m p l i n g r a t e of t h e p o r t s is l i m i t e d t o 0.4Hz. T h i s l i m i t a t i o n i s p r i m a r i l y due t o t h e maxiarum motor s p e e d of t h e e c a n i v a l v e u s e d , which i s 3 rpm.

The s o f t w a r e t o c o n t r o l t h e p r e s s u r e s u r v e y d a t a a c q u i s i t i o n o f f e r s two modes o f s c a n i v a l v e o p e r a t i o n . I n t h e f i r s t mode, s c a n i v a l v e is o p e r a t e d i n s e q u e n t i a l p o r t s e l e c t i o n . I n t h i s mode t h e p o r t numbera t o be sampled and t h e sampl ing r a t e on e a c h p o r t a r e s e l e c t a b l e by t h e user b e f o r e s t a r t i n g t h e e x p e r i m e n t . When t h i s mode of o p e r a t i o n i s s e l e c t e d , t h e sys tem homes t h e s c a n i v a l v e t o i t s p o r t 0. Then t h e s c a n i v a l v e motor i s a c t i v a t e 6 f o r B c o n t i n u o u s o p e r a t i o n and t h e p o r t numbers a r e a o n t i n u o u a l y snmpled. The d a t a is a c q u i r e d w i t h i n t h e d w e l l t i m e , when t h e p o r t number c o r r e s p o n d s t o t h e p o r t s t o be sampled. The second mode p r o v i d e s a random a c c e s s o f a p a r t i c u l a r p o r t . For t h i s mode a l s o , se lec tcbb lp p a r a m e t e r s a re t h e same. However, i n t h i s mode, t h e s c a n i v a l v e c u r r e n t p o r t number i s r e a d and compared a g a i n s t t h e p o r t t o be sampled. T h e p r o c e s s o r d e t e r m i n e s t h e d i r e c t i o n i n which t h e motor h a s t o be r o t a t e d t o r e a c h t h e nex t p o r t from which t h e d a t a h a s t o be r e a d . Based on t h i s , t h e p r o c e e s o r c o n t r o l s t h e motor a p p r o p r i a t e l y t h r o u g h t h e i n t e r f a c e . On a c c e s s i n g t h e r e q u i r e d p o r t , t h e d a t a i s a c q u i r e d a8 p e r t h e s e l e c t e d mode.

Software Design :

The s o f t w a r e d e s i g n e d f o r o v e r a l l s y s t e m o p e r a t i o n may be g rouped i n t o t h r e e p a r t s , i.e., ( i ) s y s t e m s s o f t w a r e , (ii) u s e r i n t e r a c t i o n s o f t w a r e , ( i i i ) e x p e r i m e n t d r i v e r s o f t w a r e and ( i v ) d a t a p r e s e n t a t i o n s o f t w a r e . The s o f t w a r e , e x c l u d i n g f o r t h e d a t a p r e s e n t -a t i o n h a s been deve loped i n 8086 a s s e m b l y l angauago . The s o f t w a r e f o r t h e d a t a p r e s e n t a t i o n has been deve loped on a n I B M PC c o m p a t i b l e machine s o t h a t t h e c o l o r g r a p h i c s c a p a b i l i t i e s o f t h e PC c o u l d be e x p l o i t e d . B e s i d e s i t would ease t h e n e c e s s a r y m o d i f i c a t i o n s t o t h e a p p l i c a t i o n s o f t w a r e , which a r e o f t e n r e q u i r e d from time t o time.

The u s e r i n t e r a c t i o n s o f t w a r e f o r s e t t i n g - u p t h e e x p e r i m e n t a t i o n p r o v i d e s a f r i e n d l y i n t e r f a c e , which e n a b l e s t h e u s e r

Lu progr.trei t h 3 r iyi tam f o r his a x p r i m a n t . D u r i n g t h i s e x e r c i s e , t h e s o f t w a r e e n s u r e s e r r o r - f r e e p a r a m e t e r s e l e c t i o n t h r o u g h a s e t o f h e l p messages and solf e x p l a n a t o r y q u u r i i i u . Onto l h o tlyutum i u l l ~ e t " f o r t h e e x p e r i m e n t , t h e c o n f i g u r a t i o n o f t h e e x p e r i m e n t i s s t o r e d on t h e f l o p p y a n d t h e e x p e r i m e n t d r i v e r t a k e s- o v e r t h e c o n t r o l t o i n i t i a t e t h o actuci l conduc t o f t h e e x p e r i m e n t . T h i s p a r t i n i t i a l i z e s and c o n f i g u r e s t h e subsystems i n s t r u m e n t a t i o n , and p e r f o r m s r e a l - t i m e d a t a a c q u i s i t i o n and c o n t r o l . The d a t a i s s t o r e d i n t h e f l o p p y d i s c . The s o f t w a r e p r o c e s s e s t h e d a t a o n - l i n e and a l s o r e s p o n d s a p p r o p r i a t e l y t o t h e i n t e r r u p t s f rom t h e s u b s y s t e m s i n s t r u m e n t a t i o n . The s o f t w a r e a l s o c o n t i n u o u s l y u p d a t e s t h o d i s p l a y of t h e s t a t u s i n f o r m a t i o n on t h e CRT t e r m i n a l . The u s e r may i n t e r r u p t t h e p r o c e s s , t h r o u g h t h e t e r m i n a l k e y b o a r d , e i t h e r t o h o l d / t e r m i n a t e t h e e x p e r i m e n t o r t o modi fy t h e s e t - u p i n f o r m a t i o n . On s u c c e s s f u l c o m p l e t i o n o f t h e e x p e r i m e n t , t h e c o n t r o l i s t r a n s f e r e d t o t h s d a t a p r e s e n t a t i o n e o f t w a r e .

The d a t a p r e s e n t a t i o n m e t h o d o l o g i e s h a v e been f ramed based o n t h e common e x p e r i m e n t s conduc ted i n t h e CCWT. These have been sub- div ided i n t o t h r e e c a t o g o r i e s i . e . , f l o w f i e l d da ta p r e s e n t a t i o n , f orce/rnoment d a t a p r e s e n t a t i o n and p r e s s u r e s u r v e y d a t a p r e s e n t a t i o n . The exper iment d r i v e r s o f t w a r e s t o r e s t h e d a t a on a f l o p p y , which c a n be r e a d i l y p r e s e n t e d i n t h e form o f t a b l e s . The d a t a p r e s e n t a t i o n i n t h e fo rm o f p l o t s c a n be o b t a i n e d e i t h e r t h r o u g h t h e main- frame computer DEC s y s t e m 1090 o r t h r o u g h an IBM PC c o m p a t i b l e machine. The i n t e r a c t i v e n a t u r e o f t h e p a c k a g e s d e v e l o p e d improves t h e u s e r ' s comprehens ion o f a l a rge volume of d a t a by a c h o i c e o f c o l o r s / p a t t e r n s ,

i ) Sya tems software :

The sys tem s o f t w a r e i n i t i a l i z e 8 t h e p e r i p h e r a l i n t e r f a c e s and submodules f o r a p p r o p r i a t e mode o f o p e r a t i o n . It also i n i t i a l i z e s t h e i n t e r r u p t v e c t o r t a b l e f o r i n t e r r u p t s e r v i c e h a n d l e r . The s o f t w a r e a l s o e n s u r e s a p p r o p r i a t e p r o c e e s o r r e s p o n s e f o r i n t e r f a c e s o f t w a r e and t h e a p p l i c a t i o n s o f t w a r e .

ii) User interaction software :

The h a r d w a r e h a s been d e s i g n e d , as d e s c r i b e d e a r l i e r , t o c a t e r t o a wide s p e c t r u m o f e x p e r i m e n t s l i k e i ) f l o w f i e l d s u r v e y , i i ) force/moment measurements and iii) p r e s s u r e s u r v e y s , where in the r a n g e o f s e v e r a l p a r a m e t e r s , l i k e t h e mode o f o p e r a t i o n o f t h e s u b modules, ' d a t a

ICliASF '87 HKCOHD - 59

n c q u i i i t i o n s p o c i f i c a t i o n u u t c . , w o u l d v a r y . Hence, f o r any t ; p a c i F i c e x p e r i m e n t a t i o n needed by t h e u s e r , t h e r e i s a need t o r e - c o n f i g u r e , by s o f t w a r e , t h e i n d i v i d u a l sub- sys tems and t h e s o f t w a r e- g e n e r a t e d t ime- markers . The p r e c i s e r o l e of t h e u s e r - i n t e r f a c e s o f t w a r e i s t o a c q u i r e t h e s e t - u p d a t a f r o m t h e u s e r t h r o u g h a s e t of q u e r i e s and use i t t o c o n f i g u r e t h e sub- sys tems a c c o r d i n g l y .

The q u e r i e s a r e s e l f - e x p l a n a t o r y and e a s i l y u n d e r s t a n d a b l e . The p e r m i s s i b l e answers, p a r a m e t e r r a n g e e t c . a r e d i s p l a y e d a l o n g w i t h e a c h q u e r y . I n o r d e r t o ensure e r r o r - f r e e s e t - u p e n t r i e s , t h e s o f t w a r e a c c e p t s t h e p a r a m e t e r s t h a t a r e a l l o w a b l e and i n t h e c a s e o f i n c o r r e c t e n t r i e s , an e r r o r message i s f l a s h e d on t h e CRT t o warn t h e u s e r and r e q u e s t s f o r a p e r m i s s i b l e answer . F i g u r e s 7 d e p i c t s t h e s e l e c t i o n o f t h e measurement o p t i o n s . F o r t h i s s e l e c t i o n , t h e u s e r i s a l s o prompted w i t h t h e e x p e c t e d a n s w e r s . Once t h e r e q u i r e d e x p e r i m e n t i s s e l e c t e d , t h e system draws t h e u s e r ' s a t t e n t i o n t o v e r i f y t h e e n t r i e s ( F i g u r e 7 ) . The u s e r 1s a l l o w e d t o make any a l t e r a t i o n s t o h i s s s l a c t i o n . On c o n f i r m i n g t h e o u l u c t i o n , d e p e n d i n g on t h e e x p e r l m e n t e s u l a c t u d , q u e r i e s f o r c o n f i g u r i n g t h o i n d i v i d u t i i e x p e r i m e n t s a r e i n i t i a t e d . For example,- t o e n t e r t h e s e t - u p p a r a m e t e r s f o r t h e DAS, t h e ayst4em d i s p l a y s t h o d t t f a u l t p a r a m e t e r s r e q u i r e d f o r t h e d a t a a c q u i o i t i o n and t h e mode o f r t i w d a t a o u t p u t . F o r t h u convan iuncu of' L h u u t l u r , t h e c u r s o r , l s p l a c e d a g a i n t i t e a c h of tho p a r a m e t e r s 'on t h e s c r e e n , i n t h e o r d e r shown, a n d waits f o r t h e u s e r r e s p o n s e . The e e l e c t i o n o f t h e r e s p e c t i v e p a r a m e t e r ' s v a l u e i s f u r t h e r s i m p l i f i e d by showing t h e a d m i s s i b l e r e s p o n s e / r a n g e a t t h e bot tom of t h e s c r e e n .

S i m i l a r p r o c e d u r e h a s been a d o p t e d t o c o n f i g u r e e x p e r i m e n t s f o r f l o w f i e l d survey and t h e p r e s s u r e s u r v e y s . For f l o w f i e l d survey, t h e u s e r h a s t o s e l e c t t h e mode of t h e probe t r a v e r s e c o n t r o l , e i t h e r Manual o r Automat ic . T h i s i s f o l l o w e d by d e f i n i n g t h e p robe t r a v e r s e r a n g e a n d t h e g r i d s i z e i n t h e t h r e e d i r e c t i o n s . B e s i d e s , t h e p r e s s u r e d a t a a c q u i s i t i o n t h r o u g h t h e 6- channe l d i g i t a l manomster has t o be c o n f i g u r e d . I n t h e c a s e of t h e p r e s s u r e s u r v e y e x p e r i m e n t a t i o n , t h e u s e r is r e q u e s t e d t o s e l e c t t h e p o r t numbers ( o f t h e 48 a v a i l a b l e p o r t s on t h e s c a n i v a l v e ) t o be sampled , t h e s a m p l i n g p e r i o d , and t h e number of samples f o r a v e r a g i n g . I n t h i s f a s h i o n , t h e u s e r i n t e r a c t i o n f o r c o n f i g u r i n g t h e e x p e r l m a n t a hcls besn made s e l f - e x p l a n a t o r y a n d s i m p l e .

The above u s e r i n t e r a c t i o n s o f t w a r e

f o r . t t r t t y u t - u p has been deve loped i n t h e

t h e b a s i c c e n t r a l p r o c e s s o r board and t h e a s s o c i a t e d h a r d w a r e h a v e been i n t e r f a c e d t o a n 1BbI PC compcl t ib lc i i ~ i c h i n u , n s u p a r t l t c u z e r i n t e r a c t i o n r o u t i n e w h i c h u s u s IBM PC a s a s t a n d- a l o n e c o l o r t e r m i n a l h a 5 a l s o b e e n deve loped . The p h o t o g r a p h p r e s e n t e d i n F i g u r e 7 i s f r o m t h e I B M PC t e r m i n a l , which hau an in iproved a p p e a r a n c e a s compared t o t h e b l a c k a n d w h i t e t e r m i n a l d e v e l o p e d as p a r t o f t h e sys tems hardware .

iii) Exper iment D r i v e r :

'I'he e x p e r i m e n t d r i v e r p a r t o f t h e s o f t w a r e c o n f i g u r e s a n d c o n t r o l s t h e s u b s y s t e m s , based on t h e p a r a m e t e r 8 p r o v i d e d by t h e u s e r , a n d a c q u i r e s d a t a i n r e a l t i m e , The s o f t w a r e a l so m o n i t o r s t h e h e a l t h of t h e i n s t r u m e n t s a n d c o n t i n u o u s l y u p d a t e s t h e s t a t u s o f t h e e x p e r i m e n t s on t h e C R T s c r e e n . The u s e r may a l s o i n t e r r u p t t h e p r o c e s s o r a t any s t a g e o f t h e e x p e r i m e n t , v iew t h e s o t - u p p a r a m e t e r s t h r o u g h s i m p l e commands and a l t e r them f o r t h e r e s t o f t h e e x p e r i m e n t . The e x p e r i m e n t d r i v e r s o f t w a r e f o r each o f t h e a x p e r l m e n t v i s d i s c u s s e d balow.

For f o r c e measuremunta , d e p e n d i n g o n t h e user s e t p a r a m e t e r s , t h e i n t h e manual mode, sys tem prompts t h e u s e r t o s e t t h e model p o s i t i o n i n t h e r e q u i r e d p i t c h a n d yaw. The u s e r i s t h e n r e q u i r e d tQ s e t t h e m o d u l p o s i t i o n and p r e s s ' r e t u r n ' on t h e k u y b o u r d ( I n t h u uu t ,on i t i L io modu t h u etiiiie w i l l btt d o n e by t he t lyutum). Whuri t h e ktly i s p r e s s e d , t h e s y s t e m i n i t i a t e s A / D c o n v e r s i o n o n e a c h of t h e a n a l o g c h a n n e l s by f i r s t i n i t i a l i z i n g t h e t i m e r f o r s a m p l i n g p e r i o d and t h e n by issuing a s t a r t c o n v e r s i o n command t o t h e d a t a a c q u i s i t i o n sys tem. When t h e a n a l o g t o d i g i t a l c o n v e r s i o n i s c o m p l e t e , t h e DAS i n t e r r u p t s t h e p r o c e s s o r S O t h a t t h e c o n v e r t e d d a t a i s r e a d by t h e p r o c a s s o r . The p r o c e s s o r t h a n l o o k s f o r t h e a c q u i r e d d a t a , and i f t h e d a t a is a v n i l a b l e i n t h e memory, i t w i l l be p r o c e s s e d . A t t h e i n t e r v a l s o f t h e sampling p e r i o d , t h e t i m e r i n t e r r u p t s t h e p r o c e s s o r t o a c q u i r e t h e d a t a p r e c i s e l y a t t h e s a m p l i n g i n t e r v a l s . The p r o c e s s o r k e e p s t r a c k o f t h e number o f s a m p l e s a c q u i r e d a n d when t h i s number r e a c h e s t h e s a t v a l u e , t h e t ime r i n t e r r u p t i s d i s a b l e d and t h e above p r o c e s s c o n t i n u e s u n t i l t h e da ta c o l l e c t i o n a t a l l t h e r e q u i r e d ang les i s c o m p l e t e .

When f l o w f i e l d s u r v e y i s s e l e c t e d , t h e d r i v e r s o f t w a r e i n i t i a l i z e s t h e 3- D t r a v e r s e i n t e r f a c e module f o r a u t o m a t i c probe p o s i t i o n i n g . T h u probo i u

i n f o r m a t i o n a t t h e t o p l e f t c o r n e r o f t h e

usuuf l l I ,Ly LUIl~ULLgU 01' t i08L. I I l > W U V l ~ I . , CiJ I I U W

p o s i t i o n e d u s i n g t h e user set-up

60-ICIASF '87 RECORD

f i r s t c r o s s - s e c t i o n a l p l a n e i n t h e t e s t s e c t i o n . Depend ing on t h e s t e p s i z e ( g r i d s i z e ) , i n e a c h o f t h e t h r e e d i r e c t i o n s , t h e p r o b e i s moved i n t h e l a t e r a l d i r c e t i o n ( Y - d i r e c t i o n ) i n t h e c r o s s - f l o w p l a n e . A t e a c h s t e p , a f l o w s e t t l i n g t i m e o f a b o u t 1 s e c o n d i s a l l o w e d a n d t h e n t h e d a t a a c q u i s i t i o n i s e f f e c t e d t h r o u g h t h e 6- c h a n n e l manometer. When t h e p r o b e rurraohuu thrr l u r i t gr*Itl pui . r i t r i l o n y l,tIiAt, l i n e , t h e p r o b e i s raoved t o t h e n e x t s t e p i n t h e v e r t i c a l d i r e c t i o n (downwards) a n d t h e p r e s s u r e d a t a i s c o l l e c t e d . The d i r e c t i o n o f t h e p r o b e movement a l o n g t h e l a t e r a l p l a n e is t h e n r a v u r s u d . T h i ~ i p r o c e s s i s c o n t i n u e d t o c o m p l e t e t h e s c a n n i n g o f e a c h c r o s s - f l o w p l a n e . A f t e r c o l l e c t i n g t h e f l o w f i e l d d a t a f rom t h e f i r s t p l a n e , t h e p r o b e t r a v e r s e i s moved in t h e a x i a l d i r e c t i o n t o p l a c e t h e p r o b e i n s u c c e s s i v e c r o s s - f l o w p l a n e s and t h e data c o l l . e c t i o n i s c o m p l e t e d . The p r e s s u r e d a t a f rom t h e 5- ho le p r o b e t h r o u g h t t h e manometer s u b s y s t e m i s a c q u i r e d i n i n t e r r u p t mode. T h i s a p p r o a c h makes t h e b e s t u s e o f p r o c e s s o r t i m e a n d f a c i l i t a t e s o n - l i n e d a t a r e d u c t i o n w h i l e t h e d a t a i s a c q u i r e d ' .

I n t h e c a s e o f p r e s s u r e s u r v e y e x p e r i m e n t s , t h e s c a n i v a l v e motor i s c o n t r o l l e d t o a c c e s s t h e r e q u i r e d p o r t s , i n s u c c e s s i o n , as p e r user r e q u i r e w n t s . A t e a c h o f t h e r e q u i r e d p o r t s , t h e p r e s s u r e d a t a f rom t h e LVDT p r e s s u r e s e n s o r i s a c q u i r e d t h r o u g h t h e a n a l o g DAS a a d e s c r i b e d a b o v e .

Once t h o da ta a c q u i s i t i o n f o r t h e s e l e c t G d e x p e r i m e n t a i s c o m p l e t e d , t h e d a t a p r o c e s s i n g a n d p r e s e n t a t i o n s o f t w a r e r e c e i v e s t h e c o n t r o l . T h i s p a r t h a s been d e s c r i b e d i n t h e n e x t s e c t i o n .

The a c q u i r e d d a t a , d e p e n d i n g on u s e r r e q u e s t s , h a s t o be bound c h e c k e d , a v e r a g e d a n d n o r r n a l i s e d . T h i s p r o c e s v i n g i s c a r r i e d o u t by t h e c e n t r a l p r o c e s s o r . I f t h e d a t a a c q u i s i t i o n r a t e s a r e l o w , t h e p r o c e e s o r would h a v e s u f f i c i e n t time t o c o m p l e t e this p r o c e s s i n g w h i l e t h e d a t a i s b e i n g a c q u i r e d . However, i f t h e i n t e r v a l be tween t h e a c q u i r e d d a t a i s small , t h e p r o c e s s o r would c o n t i n u e t o c o m p l e t e ' t h e p r o c e s s i n g a f t e r c o m p l e t i o n o f t h e d a t a a c q u i s i t i o n . The a c q u i r e d and t h e p r o c e s s e d d a t a a r e t h e n w r i t t e n i n t h e a u x i l l a r y s t o r a g e i n a f o r m a t a c c e p t a b l e t o IBM PC c o m p a t i b l e m a c h i n e s f o r f u r t h e r p r o c e s s i n g a n d p r e s e n t a t i o n .

iv) Data P r e s e n t a t i o n :

T h i s p a r t of t h e s o f t w a r e t h a t r u n s on t h e PC h a s t h e f o l l o w i n g f u n c t i o n s t o p e r f o r m on t h e a c q u i r e d d a t a .

( i ) R e d u c t i o n o f ae rodynamic q u a n t i t i e s

( i i) G r a p h i c a l - - V e l o c i t y v e c t o r a n d c o n t o u r c o l o u r maps o f t h e measu red d a t a ,

a n d ( i i i) F o r c e and p r e s s u r e d i s t r i b u t i o n

Uuta p r o c e s v i t i g soPtwt l re f o r f o r c e m e a s u r e m e n t s i n c l u d e s c o m p u t a t i o n o f t h e a e r o d y n a m i c c o e f f i c i e n t s . The l o c a l f l o w a n g l e and t h e v e l o c i t#y magni tude h a v e been o b t a i n e d from t h e Plow f l u l d d a t a , s u n s e d b y t h e f i v e h o l e p r o b e and t h e p r o b e c a l i b r a t i o n d a t a [221. From t h i s d a t a o t h e r p a r a m e t e r s o f i n t e r e s t a r e a l s o computed . P r e s s u r e s u r v e y d a t a f r o m t h e model o r f rom t h e model wake i s p r o c e s s e d t o y i e l d t h e l o a d d i s t r i b u t i o n o v e r t h e b o d y o r t h e p r e s s u r e l o s s i n t h e wake. T h e s e r e s u l t s a r e used t o c a l c u l a t e t h e n e c e s s a r y a e r o d y n a m i c q u a n t i t i e s .

The d a t a p r e s e n t a t i o n s o f t w a r e f o r t h e f o r c e a n d p r e s s u r e results i s i m p l e m e n t e d i n t h e u s u a l manner t h r o u g h w h i c h m u l t i p l e c o l o r p l o t 8 o f c o m p u r a b l e p a r a m e t e r s c o u l d be o b t a i n e d . I n t h e cc18e o f f l o w f i e l d d a t a p r e s e n t a t i o n , t h e s o f t w a r e d e v e l o p e d p r o v i d e s t h e u s e r w i t h t h e v e l o c i t y v e c t o r p l o t s on a HP7470 c o l o r g r a p h i c s p l o t t e r . F o r a q u i c k v i s u a l i s a t i o n o f t h e flow f i e l d a r o u n d t h e m o d e l , a s o f t w a r e package h a s b e e n d e v e l o p e d t o p r e s e n t t h e v e l o c i t y d a t a ( o r l o c a l head l o s s ) i n t h e fo rm o f c o l o u r g r a p h i c c o n t o u r p l o t s on t h e PC. U a i n g t h i s pcickage~, t h e c o n t o u r s o f s e l e c t i v e m a g n i t u d e s o f t h e f l o w f i e l d may b e p l o t t e d . C o r r e s p o n d i n g t o t h e u s e r ' s c h o i c e , t h e s o f t w a r e f i r s t s e a r c h e s f o r a n d s e p a r a t e s o u t t h e i s o- m a g n i t u d e d a t a f r o m t h e v e l o c i t y d a t a . Then t h e e q u i v e l o c i t y c o n t o u r s a r e d i s p l a y e d i n c o l o u r g r a p h i c s . The r a n g e be tween t h e a d j a c e n t c o n t o u r s i s shaded w i t h d i f f e r e n t c o l o u r p a t t e q n s . T h i s p r o v i d e s a q u i c k , v i s u a l a p p r e c L a t i o n of t h e f l o w f i e l d a r o u n d t h e t e s t model i n a n e a s y a n d i n e x p e n s i v e way. However, i f some c o n t o u r s a r e c l o s e l y s p a c e d , d e p e n d i n g o n t h e a c t u a l l a y o u t o f t h e c o n t o u r s , t h e p a t t e r n s u s e d t o s h a d e t h e r e g i o n s may l e a d t o c o n f u s i o n . T h i s h a s been ove rcome by p r o v i d i n g t h e u s e r w i t h an o p t i o n t o c h a n g e t h e c o l o u r p a t t e r n s a f t e r e x a m i n i n g t h e c o n t o u r p l o t s p r e s e n t e d on t h e s c r e e n . The a v a i l a b l e c o l o u r p a t t e r n s a re shown a d j a c e n t t o t h e p l o t w i t h an i n d i c a t i o n o f t h e d e f a u l t colours a s s i g n e d t o t h e s e l e c t e d m a g n i t u d e r a n g e s . Through t h e k e y b o a r d , t h e u s e r can s e l e c t a p a t t e r n a n d g i v e a command t o f i l l u p t h e s e l e c t e d c o n t o u r r e g i o n . R e p r e s e n t a t i v e p h o t o g r a p h s o f t h e c o l o r g r a p h i c s d i s p l a y s

from t h e a c q u i r e d d a t a ,

p l o t s .

(CIASF '87 RECORD-41

o f t h e f low f i e l d d a t a have been g i v e n i n F i g u r e s 8 and 9. The f i n a l formu o f Lha d i s p l a y s oould a l s o be saved f o r f u L u r e r e f e r e n c e .

C o n c l u s i o n s :

The hardware and t h e s o f t w a r e o f t h e i n t e g r a t e d i n 8 t rumen t a t i o n s y s tem t h a t i s s u i t a b l e t o small s c a l e wind t u n n e l a p p l i c a t i o n s h a s been s u c c e s s f u l l y d e s i g n e d and r e a l i s e d . The sys tem has been i n s t a l l e d i n t h e CCWT a t 1 . 1 . S ~ . and t e s t e d , R e p r e s e n t a t i v e c o l o r g r a p h i c s p l o t s have been p r e s e n t e d . S i n c e t h e i m p o r t a n t f e a t u r e , i n t h e s e p l o t s is t h e d i f f e r e n t c o l o r s , t h e same may n o t be e f f e c t i v e l y s e e n i n t h e f i n a l form of t h e p a p e r . However, we e x p e c t a d i s t i n g u i s h a b l e g r a d a t i o n i n t h e c o n t o u r levels i n t h e f i n a l p i c t u r e s .

Acknowledgements :

The a u t h o r s g r e a t f u l l y acknowledge t h e A e r o n a u t i c a l Research and Development Board f o r f u n d i n g tiis p r o j e c t . The a u t h o r s wi8h t o acknowledge P r o f . Ramssuamy, P r o f . S . P . C o v l n d a r a j u arid Prof, P.R. Mahapatra f o r t h e i r u s e f u l s u g g e s t i o n s . The a u t h o r 8 wish t o t h a n k Mi-. B . A . Mtldankumclr f o r h i 8 a c t i v u o u p p o r t i n t h e p r e p e r a t i o n o f t h e m a n u s c r i p t . 4

R e f e r e n c e s :

[ 1 ] C . Ravikumar, " A M i c r o p r o c e s s o r baaed I n t e g r , a t e d System f o r Wind Tunne l A p p l i c a t i o n s t ! , M. Sc. (Engg. ) T h e s i s , 1986.

[2] M. Konig and H . J . P f e i f e r , "LDA d a t a a c q u i s i t i o n s y s t e m s w i t h h i g h a c c u r a c y and h i g h d a t a r a t e " , ICIASF '77 Record, pp. 13- 21, 197'7.

[ 3 ] A . B o u t i e r , C. F e r t i n and J . L e f e v r e , " L a s e r v e l o c i r n u t e r f o r wind tunnel. measurementsf t , ICAISF ' 7 7 Record , pp.

[ 4 ] W.J. Yanta , " A t h r e e d i m e n s i o n a l l a s e r d o p p l a r v e l o c i m e t e r f o r u s e i n wind t u n n e l s b 1 ICIASF ' 7 9 , Record, pp. 294-301, 1479.

[ 5 ] D.W. Schmid t , " A c c o u s t i c a l methods f o r f a s t d e t e c t i o n and measurement o f v o r t i c e s i n wind t u n n e l s " , ICIASF ' 7 5 Record , pp. 216-228, 1975.

[6] R . H . E n g l e r , H . H o l s t , D.W. Schmidt and R I Wulf, "Measurement o f v o r t i c e s i n wind t u n n e l e x p e r i m e n t s by U B ~ o f u l t r a s o n i c p u l s e a l l , ICIASF ' 7 9 Record , pp. 163-170, 1979.

[ 7 ] C . Meyer, "Wind t u n n e l measurements w i t h a n e l e c t r o n i c a l l y s c a n n e d m u l t i p o r t p r e s s u r e s e n s o r l l , ICIASFI81 Record , 1981.

1-12; 1977.

[81 C.F. Coe, C . T . P a r r a and R . C . Kuuf'firiun, " A naw e l u c t r o n i c t i c u n n u r o f p r e s s u r e des igned for i n s t a l l l a t i o n i n wind t u n n e l modelstl, ICIASF '81 R e c o r d , 1981.

[ 9 ] IIMACSYM 20 - Users Manualft , Analog D e v i c e s , I n c o r p o r a t e d , USA.

[ l o ] A.E. Winkelmann, and C . P . TSAO, " A c o l o r v i d e o d i s p l a y t echn ique f o r f l o w f i e l d s u r v u y e t f A I A A Journal, v o l . 2 3 ( 9 ) , p . 1 3 8 1 , September 1985.

[113 t r i A P X 8 6 , 8 8 User 's Manual", I n t e l C o r p o r a t i o n , Augus t 1981.

[ 121 Robin J i g a u r , "Using t h e 8259A p r o g r am ma b 1 e i n t e r r u p t c on t r o 11 a r I t , A p p l i c a t i o n Note AP- 59, I n t e l C o r p o r a t i o n , 1979 .

[131 "Using t h e 8251 U n i v e r s a l Synchronous / Asynchronous R e c e i v e r / T r a n s m i 1 t e rll P e r i p h e r a l d e s i g n handbook, h t e l C o r p o r a t i o n , pp. 2.241-2.270, Augus t 1981.

[ 1 4 ] David B .Gus tavson , tfComputer Buses-A T u t o r i a l t 1 , I E E E Micro , August 1984.

[ 1 5 1 J o e B a r t h m a i e r , t f X n t e l m u l t i b u s i n t e r f a c i n g f t , A p p l i c a t i o n Note , AP 284 , I n t e l C o r p o r a t i o n , 1979.

[ I 6 1 Z . M . Rtimly, E I and W.J. R a n b i r d , ItGomputer controlled system f o r t h e i n v a u t i g a t i o n o f t h e f low beh ind wingsl l , J o u r n a l o f A i r c r a f t , v o l .

[171 l l O p t o - u l e c t r o n i c s cornporittnt Hund B o o k t f , G e n e r a l I n s t r u m e n t s , U S A ,

[ I 8 1 S.P. G o v i n d a r a j u , N. B a l a k r i s h n a n and C . Ravikumar , "Development of a p r e s s u r e a e n s o r w i t h d i g i t a l o u t p u t b a s e d on a l i q u i d manometer" , P r o c . o f 1 1 t h N a t i o n a l symposium on f l u i d mechan ics and f l u i d power, pp. A P l 4 - 1 9 , December 1982 .

[ 1 9 ] C . Ravikumar a n d N . B a l a k r i s h n a n , " A low c o s t m i c r o p r oc e s s o r based m u l t i p l e p r e s s u r e measur ing system!', t o a p p e a r i n J o u r n a l of Microcomputer A p p l i c a t i o n s , Academic P r e s s , v o l . 1 0 , 1987.

[ 2 0 ] S .P . G o v i n d a r a j u , and V.S. I i o l l a , "Design o f k h e p i t c h and t h e yaw mechanism f o r a wind t u n n e l w ' , T e c h n i c a l R e p o r t No; AE-380/A, 1984.

L21.1 C . Ravikumar , M . A . Ramaswaruy and V.S. H o l l a , " C a l i b r a t i o n of the s i x component s t r a i n gauge b a l a n c e for t h e CCWTII T e c h n i c a l Repor t No .AE- 397/A, 198b .

[ 2 2 ] R . Wickens , P. S o u t h , R.S. Rangi and D . Henshaw, " E x p e r i m e n t a l development i n V/STOL wind t u n n e l t e s t i n g a t t h e n a t i o n a l a e r o n a u t i c a l e s t a b l i s h m e n t t t , Canad ian a e r o n a u t i c s and s p a c e j o u r n a l , v o l . 1 9 , pp. 145-154, A p r i l

1 4 ( 7 ) , pp. 668-674, J ~ l y . 1 9 7 7 .

1979 .

/

1973.

62-ICIASF '87 RECORD

r -

r

Model c o n t r o l ode1 control

S h a f t Encoders notors

.3-D Traverse Interface Mechanism for 3- D Probe Motors, sensors Traverse 9

System .F

Pre s sur e P=ocesa*r Tappings - 6-channel Interface for From ~6-channel Unit

r

D i g . nanometer

I Computer I L-----i

Pressure @-port Scanivalve Ports Interface

FIG. 1. CONFIGURATION OF TEE SYSTEM

E

Merory (ROM & R A M )

I / O Decoder I

Programable I/O 8255 ( 3 )

Memory * /' Decoder '

MULTIBUS I n t e r f a c e Logic

r

CPU - 8086 r

I I n t e r r u p t s

r

Addres 8 Data ,' L a t c h Buf fe r

V I

f MULTI BUS I FIG. 2. SYSTEM PROCESSOR U N I T

BUS Contr,

4

FIG. 3 . 3-D PROBE POSITION CONTROL INTlEHPAClG

I ?

System Proceseor BUS (Mul t ip l exed) I

64-ICIASF '87 RECORD

motor d i s c v i t h h o l e s

P U l l Y

Lase U- tubes 76 s e t e ) -\

Motor ON/OFF

- o p t i c a l s0nsor

a ) . M e c h a n i c a l Set-up

Motor Control C i r c u i t r y *

I A I

O p t i c a l l i m i t 1 senaore I

Lower \ S e n s o r

I ) I n Upper C i r c u i t r y

8 - b i t l a t c h data

+ P o r t A* b

. PPI O p t i c a l c l o c k

D i s t a n c e 8255 8 L e v e l Sensor J Lower o r t

8 - b i t l a t c h I l i ALE

I

/ -

b). E l e c t r o n i c s Interface

FIG. 4. 6 - CHANNEL DIGITAL MANOMETER

System

P r o ce B sor

J

ICIASF '87 RECORD -65

Decoder

addrees

FIG. 5 . 32 - CHANNEL ANALOG DATA ACQUISITIQN SYSTEM

a p t i c a l g r a y 6 b i t

sensor

Syste.

ai I

motor c o n t r o l c i r c u i t r y IC

24v DC

FIG. 6. SCANIVALVE INTERFACE

66-ICIASF '87 RECORD

FIG. 7. USER INTERFACE Set- 'UP Mode

FIG. 8. COLOR G R A P H I C S ISOMACNITUDE P L O T S - Equivelocity Contours at x /d = 2.4 alpha = 18, Vinf = 30 D/S (body : ogive nose-cylinder body of l/d=10) -- Color pattern selection

FIG. 9. COLOR G R A P H I C S P L O T S - continued -- after completing the color pattern selection and before saving the picture.

BRIEF BIOGRAPHIES OF AUTHORS

C. Ravikumar graduated in 1979 from Nagarjuna University, Guntur, India and received M.Sc. degree in engineering physics and instrumentation in 1981 from Osmania University, Hyderabad, India. In 1981 he joined the department of Aerospace Engineering, Indian Institute of Science, Bangalore, India where he was employed as a Scientific Assistant. At the Indian Institute of Science he had also completed a research oriented M.Sc. (Engg) degree. His fields of interest include microprocessor based instrumentation, microcomputer systems and computur orig inuering .

N. Balakrishnan received the BE degree in electronics and communications from the University of Madras, India in 1972 and the Ph.D. degree from the department of Aerospace Engineering, Indian Institute of Science, Bangalore, India in 1979.

In 1973 he joined the Department of Aerospace Engineering where he is currently employed as Associate Professor. His fields of research interest include numerical electromagnetics, space craft antennas, computer science and microprocessor systems. '

Prof. Balakrishnan is a life member of the Instrument Society of India and is on the editorial board of the Current Science Journal. He is the recipient of the UNESCO/ROSTCA award for outstanding contributions in the area of computers and informatics for the year 1985. He is the Convener of the Centre for Microprocessor Applications and also the Centre for Science Information at' the Indian Institute of Science. He is also a consultant to lhading Government and Private industries

. .

V.S. Holla received the B.Sc. (1956) and B.Ed. (1960) degrees from Mysore University, India, the M.Sc. (Mathematics) degree from Karnataka University in 1961 and the Ph.D. degree from Indian Institute of Science, Bangalore, India, in 1969. He joined the department o f Aerospace Engineering, Indian Institute of Science in 1965 as a Technical Assistant and is currently an Associate Professor in Aerodynamics. His interests are in Theoretical and Experimental Aerodynamics and has been working in this area for the last 2 2 years.

Prof. Holla l a a member of the'Aeronautica1 Society of India. He is also on the Editorial Boar4 of the Journal of Aeronautical Society of India, as an Associate Editor since 1980.

68-ICIASF '87 RECORD