9
ORIENTATION
The orientation of the EXLs3 in the space is represented by a
unit quaternion
(
q
0
, q
1
, q
2
, q
3
)
representing the
rotation
of the unit’s
body frame
with respect to the
earth frame
.
The quaternion’s components returned by the EXLs3 are normalized so that the
unity
is represented by
the value
16384
. So the following formula should be applied:
q
n
=
𝑄
𝑛
16384
n = 0,1,2 and 3
The rotation of the
body-frame
is identified by an
axis of rotation A
and an
angle of rotation
α
around that
axis:
q
0
= cos(α / 2)
q
1
= A
x
sin(α / 2)
q
2
= A
y
sin(α / 2)
q
3
= A
z
sin(α / 2)
EXAMPLES:
A rotation of +90 degrees around the Z axis (0,0,1) results:
q
0
= cos(90 / 2)
= 0.7071
q
1
= 0 sin(90 / 2)
= 0
q
2
= 0 sin(90 / 2) = 0
q
3
= 1 sin(90 / 2) = 0.7071
A rotation of -90 degrees around the Y axis (0,1,0) results:
q
0
= cos(-90 / 2)
= 0.7071
q
1
= 0 sin(-90 / 2)
= 0
q
2
= 1 sin(-90 / 2)
= -0.7071
q
3
= 0 sin-(90 / 2)
= 0
The
Identity Quaternion (1,0,0,0)
indicates the unit’s body frame (X-Y-Z) is aligned with the North-West-Up earth-frame.
7. BLUETOOTH SETUP
The communication with the unit is done via bluetooth SPP connection, so you should have a
Bluetooth
2.1
internal card or USB Bluetooth
dongle
properly installed on your host machine.
After, you must
pair
each EXLs3 with the host by going to
View Devices and Printers (under Windows 7)
and clicking on
Add a device
. Note your EXLs3 device(s) must be switched-on in order to be
discoverable by the host.