<s>
An	O
attitude	B-Device
and	I-Device
heading	I-Device
reference	I-Device
system	I-Device
(	O
AHRS	B-Device
)	O
consists	O
of	O
sensors	O
on	O
three	O
axes	O
that	O
provide	O
attitude	O
information	O
for	O
aircraft	O
,	O
including	O
roll	O
,	O
pitch	O
,	O
and	O
yaw	O
.	O
</s>
<s>
These	O
are	O
sometimes	O
referred	O
to	O
as	O
MARG	B-Device
(	O
Magnetic	O
,	O
Angular	O
Rate	O
,	O
and	O
Gravity	O
)	O
sensors	O
and	O
consist	O
of	O
either	O
solid-state	O
or	O
microelectromechanical	B-Architecture
systems	I-Architecture
(	O
MEMS	B-Architecture
)	O
gyroscopes	B-Application
,	O
accelerometers	O
and	O
magnetometers	O
.	O
</s>
<s>
The	O
main	O
difference	O
between	O
an	O
Inertial	O
measurement	O
unit	O
(	O
IMU	O
)	O
and	O
an	O
AHRS	B-Device
is	O
the	O
addition	O
of	O
an	O
on-board	O
processing	O
system	O
in	O
an	O
AHRS	B-Device
,	O
which	O
provides	O
attitude	O
and	O
heading	O
information	O
.	O
</s>
<s>
With	O
sensor	B-General_Concept
fusion	I-General_Concept
,	O
drift	O
from	O
the	O
gyroscopes	B-Application
integration	O
is	O
compensated	O
for	O
by	O
reference	O
vectors	O
,	O
namely	O
gravity	O
,	O
and	O
the	O
Earth	O
's	O
magnetic	O
field	O
.	O
</s>
<s>
This	O
results	O
in	O
a	O
drift-free	O
orientation	O
,	O
making	O
an	O
AHRS	B-Device
a	O
more	O
cost	O
effective	O
solution	O
than	O
conventional	O
high-grade	O
IMUs	O
that	O
only	O
integrate	O
gyroscopes	B-Application
and	O
rely	O
on	O
a	O
high	O
bias	O
stability	O
of	O
the	O
gyroscopes	B-Application
.	O
</s>
<s>
In	O
addition	O
to	O
attitude	O
determination	O
an	O
AHRS	B-Device
may	O
also	O
form	O
part	O
of	O
an	O
inertial	O
navigation	O
system	O
.	O
</s>
<s>
AHRS	B-Device
is	O
reliable	O
and	O
is	O
common	O
in	O
commercial	O
and	O
business	O
aircraft	O
.	O
</s>
<s>
AHRS	B-Device
is	O
typically	O
integrated	O
with	O
electronic	B-Device
flight	I-Device
instrument	I-Device
systems	I-Device
(	O
EFIS	B-Device
)	O
which	O
are	O
the	O
central	O
part	O
of	O
glass	B-Device
cockpits	I-Device
,	O
to	O
form	O
the	O
primary	O
flight	O
display	O
.	O
</s>
<s>
AHRS	B-Device
can	O
be	O
combined	O
with	O
air	O
data	O
computers	O
to	O
form	O
an	O
Air	O
data	O
,	O
attitude	B-Device
and	I-Device
heading	I-Device
reference	I-Device
system	I-Device
(	O
ADAHRS	B-Device
)	O
,	O
which	O
provide	O
additional	O
information	O
such	O
as	O
airspeed	O
,	O
altitude	O
and	O
outside	O
air	O
temperature	O
.	O
</s>
