A view on machine vision

coatiarfΤεχνίτη Νοημοσύνη και Ρομποτική

17 Οκτ 2013 (πριν από 4 χρόνια και 22 μέρες)

94 εμφανίσεις

www.abb.com/robotics
26
pa c k a gi n g T e c h p a g e s

U s e r s o f m o d e r n p a c k a g i n g l i n e s e x p e c t a
l o t f r o m t h e i r i n s t a l l a t i o n s. Ty p i c a l l y, p r o d -
u c t s o f v a r y i n g s i z e a n d s h a p e a r e p r e s e n t e d
f o r p a c k a g i n g a t r a n d o m i n t e r v a l s a n d i n
r a n d o m o r i e n t a t i o n s. I n p r i n c i p l e, r o b o t
t e c h n o l o g y o f f e r s t h e f l e x i b i l i t y n e e d e d t o
c o p e w i t h t h e s e v a r i a t i o n s, b u t i t c a n ’ t d o
s o u n l e s s i t h a s s o m e w a y o f a c c u r a t e l y
d e t e r m i n i n g p r o d u c t s i z e, p o s i t i o n a n d
orientation.
The central ingredient of the most ver-
satile solutions is a machine vision system
but, in itself, such a system is not a com-
plete solution. Almost any modern machine
vision system from a reputable manufac-
turer will be capable of producing good
quality data, but the real issues are how that
data is used, and how easy the system is to
work with.
It’s important to bear in mind that
machine vision system manufacturers pro-
duce equipment that can be used in a wide
range of applications; it is not specifically
optimized for use with robots. This means
that although the equipment offers all of
the facilities – such as geometric pattern
matching and blob analysis – needed for
robot control, it will often be unnecessarily
Software to save the day
PickMaster is the ABB Packaging soft-
ware that simplifies robot integration in
picking, packing, palletizing and mate-
rial handling. The software saves time
in the engineering phase by reducing
the need of robot programming to a
minimum. The software is loaded with
application tools that make it easy to
meet a range of requirements. The
graphical design concept and software
structure are easy for operators to
understand and use.
The software employs an advanced
vision technique and tightly integrated
conveyor tracking capability. The inte-
grated vision system is advanced, but
is open to communicate with any exter-
nal sensor - line scanners, color vision,
3D or others – and is ideal for high
speed picking applications. The soft-
ware works well regardless of whether
products come in at random, on guided
conveyors or are placed on indexed
carriers for highest precision.
PickMaster can be used as a
standard tool for vision guidance of
ABB robots. Tightly integrated with
the IRC5 control system, it is an ideal
tool for guiding robots in the packag-
ing process. point random objects,
the PC-based software uses a high
performance robust vision system. It
identifies and transfers 360-degree ran-
dom objec ts in 50 to 200 milliseconds.
Powerful quality inspection tools can
categorize products and make sure
defective ones are sorted out.
PickMaster can control up to eight
robots and eight cameras, working
together in one application or in multi-
ple independent processes. The work
load can be distributed evenly between
all robots and it is even possible for
the fellow robots to take over the work
of others which they may have missed.
A complete line can be operated from
a remote panel, PLC or PC, through
field buses or any other communica-
tion link.
For palletizing, the software
can handle multiple in-feeders and
multiple out-feeders in simultaneous
production. Mixing different products
from many stations to one pallet is as
easy as distributing loads to several
palletizing stations. A powerful pallet-
pattern generator is included involving
multi-drop move ments with multi-zone
vacuum tools or mechanical grippers.
>FactS
A vi ew on machi ne vi si on
the usef ul ness of a vi si on
syst em i n a packagi ng l i ne
depends as much on how
wel l i t i s i nt egr at ed as i t
does on t he per f or mance
of t he syst em i t sel f.
di f f i c ul t f or t he e nd us e r of t he pa c ka g i ng
ma c hi ne t o a c c e s s a nd us e t he s e f a c i l i t i e s.
The f i r s t pr obl e m t ha t ne e ds t o be
a ddr e s s e d i s c ommuni c a t i on be t we e n t he
v i s i on s y s t e m a nd t he r obot c ont r ol l e r. Thi s
i s, of c our s e, a n i s s ue f or t he s uppl i e r of
pa c ka g i ng ma c hi ne, but i t ’s i mpor t a nt t o
us e r s i n t ha t f a s t a nd de pe nda bl e c ommuni -
c a t i on i s e s s e nt i a l f or a c hi e v i ng hi g h l e ve l s
of pr oduc t i v i t y.
Us e r s e x pe c t t oda y’s pa c ka g i ng l i ne s t o
be v e r y pr oduc t i v e, wi t h a ve r a g e t hr oug hput
r a t e s of s e v e r a l hundr e d pa c ks pe r mi nut e
be i ng qui t e t y pi c a l.
Thi s hi g h s pe e d of ope r a t i on pl a c e s
c ons i de r a bl e de ma nds on t he r obot c on-
t r ol l e r – powe r f ul pr oc e s s or s a r e ne e de d,
c oupl e d wi t h s of t wa r e whi c h i mpl e me nt s
www.abb.com/robotics
27
T e c h p a g e s
R e a d i n g t h e u n r e a d a b l e
A p a r t n e r o f A B B, B o s t o n, U.S.-
b a s e d C o g n e x s p e c i a l i z e s i n v i s i o n
s y s t e m s, a m o n g o t h e r t h i n g s, u s e d
i n m a n u f a c t u r i n g a u t o m a t i o n. C o g n -
e x i s a l s o a l e a d e r i n i n d u s t r i a l I D
r e a d e r s.
C o g n e x s p e c i a l i z e s i n v i s i o n
s y s t e m s t h a t c a n e a s i l y h a n d l e
f l e x i b l e, n o n - p l a n a r p a c k a g e s, n o n -
l i n e a r s c a l i n g, p e r s p e c t i v e v i e w s
a n d s h r i n k w r a p p i n g. F o r e x a m -
p l e, t h e s y s t e m c a n f i n d a c c u r a t e
l o c a t i o n s o f p a c k a g e s w h e r e t h e
p a c k a g e a n d t h e i n f o r m a t i o n o n i t
a p p e a r s t o b e s t r e t c h e d o u t d u e t o
m o v i n g p a l l e t s w i t h c h a n g i n g o r i e n -
t a t i o n s, o r t o l e r a t e m i s a l i g n m e n t o f
p a c k a g e s o r p r o d u c t s.
W h i l e f i n d i n g t h e p a c k a g i n g
p o s i t i o n, t h e s y s t e m c a n f i n d m i s s -
i n g p a r t s, v e r i f y p r i n t e d i n f o r m a t i o n
a n d f i n d p r i n t d e f e c t s, a s w e l l a s
i d e n t i f y c o s m e t i c d e f e c t s o r w r o n g
p a r t s. T h e s y s t e m c a n v e r i f y t h a t
p a c k a g e l a b e l s m a t c h t h e i r 2 D o r
b a r c o d e p r o d u c t c o d e, a n d c a n
m a k e 3 6 0 d e g r e e p a c k a g e i n s p e c -
t i o n w i t h o u t r e q u i r i n g r o t a t i o n o f
p r o d u c t s. T h e r e i s n o n e e d t o h a v e
t h e l a b e l f a c i n g t h e c a m e r a, n o
n e e d t o s l o w t h e l i n e t o r o t a t e t h e
p a c k a g e, a n d t h e l a b e l i n f o r m a t i o n
c a n b e o n l y p a r t i a l l y v i s i b l e i n o n e
o r m o r e v i e w s.
R e a d m o r e a t w w w.c o g n e x.c o m
f a s t b u t s t a b l e c o n t r o l l o o p s f o r t h e r o b o t
m o t i o n. A l l o f t h i s i s, h o w e v e r, o f l i t t l e
v a l u e i f t h e c o m m u n i c a t i o n l i n k w i t h t h e
v i s i o n s y s t e m i s s l o w o r u n r e l i a b l e.
E v e n t h e b e s t s o f t w a r e a n d b e s t c o m -
m u n i c a t i o n s l i n k s a r e, h o w e v e r, o f l i t t l e
v a l u e u n l e s s e n d u s e r s c a n t a k e f u l l a d v a n -
t a g e o f t h e i r p o t e n t i a l. U n t i l r e c e n t l y, t h i s
w a s m o r e d i f f i c u l t t h a n i t s o u n d s – b o t h
v i s i o n s y s t e m s a n d r o b o t s h a d a d e s e r v e d
r e p u t a t i o n f o r b e i n g h a r d t o s e t u p.
F o r t u n a t e l y, d e v e l o p m e n t s
i n u s e r i n t e r -
f a c e t e c h n o l o g y m e a n t h a t t h i s i s n o l o n g e r
t h e c a s e. T h e b e s t r o b o t i c s y s t e m s h a v e
g r a p h i c a l p r o g r a m m i n g s y s t e m s w h i c h a r e
b a s e d o n f a m i l i a r Wi n d o w s t e c h n o l o g y a n d
w h i c h a r e v e r y i n t u i t i v e i n u s e. T h e d a y s o f
d e v e l o p i n g m a n u a l l y c o d e d p r o g r a m s f o r
e a c h a p p l i c a t i o n a n d e v e n e a c h p r o d u c t a r e
o v e r.
I n a d d i t i o n, l e a d i n g s u p p l i e r s o f r o b o t i c
p a c k a g i n g m a c h i n e s p r o v i d e t h e i r o w n
i n t e r f a c e f o r t h e v i s i o n s y s t e m. I n s t e a d o f
t h e u s e r h a v i n g t o g r a p p l e w i t h t h e f u l l
r a n g e o f f u n c t i o n s o f f e r e d b y t h e v i s i o n
s y s t e m m a n u f a c t u r e r, m a n y o f w h i c h a r e
i r r e l e v a n t i n r o b o t a p p l i c a t i o n s, t h e y a r e
p r e s e n t e d w i t h s e l e c t e d f u n c t i o n s w h i c h
h a v e b e e n o p t i m i s e d f o r u s e w i t h r o b o t s.
E s s e n t i a l o p e r a t i o n s, s u c h a s s y s t e m
c a l i b r a t i o n a n d o b j e c t i d e n t i f i c a t i o n, w h i c h
h a v e, i n t h e p a s t b e e n t e d i o u s a n d t i m e
c o n s u m i n g, c a n b e a u t o m a t e d. U s e r s c a n
a l s o b e p r o v i d e d w i t h a l i b r a r y o f f u n c t i o n s
– s u c h a s c h e c k i n g t h a t e v e r y p o s i t i o n i n a
t r a y o f p r o d u c t s i s p r o p e r l y f i l l e d – i n s t e a d
o f h a v i n g t o p r o g r a m t h e s e f u n c t i o n s f r o m
s c r a t c h. T h e r e s u l t i s b i g s a v i n g s i n m a c h i n e
s e t - u p t i m e.
T i g h t i n t e g r a t i o n b e t w e e n t h e r o b o t
c o n t r o l l e r a n d t h e v i s i o n s y s t e m c a n a l s o
p r o v i d e t h e b a s i s f o r o t h e r b e n e f i t s, s u c h
a s t h e a u t o m a t i c s h a r i n g a n d b a l a n c i n g
o f t h e w o r k l o a d b e t w e e n m u l t i p l e r o b o t s
u s e d i n a p a c k a g i n g m a c h i n e. T h i s e n a b l e s
t h r o u g h p u t a n d o p e r a t i n g e f f i c i e n c y t o b e
m a x i m i z e d.
M a c h i n e v i s i o n s y s t e m s p r o v i d e n o t
o n l y m o t i o n c o n t r o l, h o w e v e r. T h e y c a n
a l s o p r o v i d e o t h e r f u n c t i o n s, s u c h a s a u t o -
m a t i c i n s p e c t i o n. F o r i n s t a n c e, a v i s i o n s y s -
t e m c a n i n s p e c t t h e p r o d u c t i t s e l f, d e t e c t i n g
a l l k i n d s o f v i s u a l d e f e c t s s u c h a s i n c o r r e c t
s h a p e a n d p o o r c o l o r. T h e s y s t e m c a n a l s o
i n s p e c t t h e p a c k a g i n g, r e v e a l i n g p r o b l e m s
l i k e m i s s i n g o r i l l e g i b l e d a t e s t a m p s, m i s s i n g
l a b e l s a n d i n c o r r e c t l y f i l l e d p a c k s.
B e s t o f a l l, i n m o s t c a s e s, i n s p e c t i o n c a n
b e a c c o m p l i s h e d w i t h t h e s a m e v i s i o n s y s -
t e m t h a t i s b e i n g u s e d f o r c o n t r o l p u r p o s e s.
T h e i n c r e m e n t a l c o s t o f t h i s a d d i t i o n a l
f u n c t i o n a l i t y i s, t h e r e f o r e, m i n i m a l b u t t h e
s a v i n g s i t d e l i v e r s b y d o i n g a w a y w i t h m a n -
u a l i n s p e c t i o n c a n b e v e r y s u b s t a n t i a l.
I n p a c k a g i n g a p p l i c a t i o n s, v i s i o n s y s -
t e m s s h o u l d b e c o n s i d e r e d a s a n i n t e g r a l
p a r t o f e v e r y r o b o t - b a s e d i n s t a l l a t i o n. A s
w e ’ v e s e e n, h o w e v e r, t h e p e r f o r m a n c e o f
t h e v i s i o n s y s t e m i t s e l f i s a r e l a t i v e l y m i n o r
c o n c e r n w h e n e v a l u a t i n g t h e i n s t a l l a t i o n ’ s
o v e r a l l c a p a b i l i t i e s.
C o g n e x v i s i o n s y s t e m i s u s e d b y U n i l e v e r
i n G e r m a n y, b e l o w. A P i c k M a s t e r m u l t i - f e e d
s i m u l a t i o n v i e w, a t l e f t.