KEYSIGHT: Computer Vision Inspection of Valve Spring Assemblies on Engine Heads

The movie d e s c r i b e s a computer v i s i o n program used to i n s p e c t v a l v e s p r i n g assemb l i es on eng ine heads f o r t h e presence o f v a l v e s p r i n g cap k e y s . A m i s s i n g key can cause c o n s i d e r a b l e eng ine damage as the assembly w i l l u l t i m a t e l y come a p a r t , d r o p p i n g the v a l v e o n t o t h e p i s t o n . A t t he a u t o m a t i c i n s p e c t i o n s t a t i o n , t h e eng ine head is moved pas t a l i n e a r a r r a y camera wh ich t a k e s a 64 by 64 p i x e l p i c t u r e o f t he area near each v a l v e s p r i n g assemb l y c e n t e r . The program f i r s t f i n d s t he c e n t e r o f each assembly and then checks f o r t he presence of bo th k e y s . The c e n t e r i s found by : (1 ) o b t a i n i n g a t h i n n e d edge a r r a y (wh i ch has c o n s i d e r a b l e c i r c u l a r symmetry) f rom the p i c t u r e i n t e n s i t y a r r a y , and (2 ) f i n d i n g t h e v e r t i c a l and h o r i z o n t a l axes o f symmetry. The i n s p e c t i o n i n v o l v e s e x a m i n a t i o n o f the i n t e n s i t y p r o f i l e a l ong the c i r c u m f e r e n c e o f a c i r c l e wh ich passes t h r o u g h the c e n t e r o f the expec ted key l o c a t i o n . The keys va ry s i g n i f i c a n t l y i n b r i g h t n e s s , bu t they a re a lways b r i g h t e r t han the h o l e formed by t h e absence of a k e y . KEYSIGHT, wh ich i n s p e c t s 400 heads per hour at assembly l i n e speeds , has demons t ra ted c o s t e f f e c t i v e n e s s and h i g h r e l i a b i l i t y .