<s>
Joint	B-Algorithm
constraints	I-Algorithm
are	O
rotational	O
constraints	O
on	O
the	O
joints	O
of	O
an	O
artificial	O
system	O
.	O
</s>
<s>
They	O
are	O
used	O
in	O
an	O
inverse	B-General_Concept
kinematics	I-General_Concept
chain	O
,	O
in	O
fields	O
including	O
3D	O
animation	O
or	O
robotics	O
.	O
</s>
<s>
Joint	B-Algorithm
constraints	I-Algorithm
can	O
be	O
implemented	O
in	O
a	O
number	O
of	O
ways	O
,	O
but	O
the	O
most	O
common	O
method	O
is	O
to	O
limit	O
rotation	O
about	O
the	O
X	O
,	O
Y	O
and	O
Z	O
axis	O
independently	O
.	O
</s>
<s>
To	O
simulate	O
joint	B-Algorithm
constraints	I-Algorithm
more	O
accurately	O
,	O
dot-products	O
can	O
be	O
used	O
with	O
an	O
independent	O
axis	O
to	O
repulse	O
the	O
child	O
bones	O
orientation	O
from	O
the	O
unreachable	O
axis	O
.	O
</s>
