ADIS16209_08 AD [Analog Devices], ADIS16209_08 Datasheet - Page 10

• Manufacturer Part Number: ADIS16209_08
• Description: High-Accuracy, Dual-Axis Digital Inclinometer and Accelerometer
• Manufacturer: AD [Analog Devices]

ADIS16209
THEORY OF OPERATION
The ADIS16209 tilt sensing system uses gravity as its only
stimulus, and a MEMS accelerometer as its sensing element.
MEMS accelerometers typically employ a tiny, spring-loaded
structure that is interlaced with a fixed pick-off finger structure.
The spring constant of the floating structure determines how
far it moves when subjected to a force. This structure responds
to dynamic forces associated with acceleration and to static
forces, such as gravity.
Figure 16 and Figure 17 illustrate how the accelerometer
responds to gravity, according to its orientation, with respect
to gravity. Figure 16 displays the configuration for the incline
angle outputs, and Figure 17 displays the configuration used
for the rotational angle position. This configuration provides
greater measurement range than a single axis. The ADIS16209
incorporates the signal processing circuit that converts accelera-
tion into an incline angle, and corrects for several known error
sources that would otherwise degrade the accuracy level.
Y AXIS TILT
DIRECTION
POSITIVE
4
5
1
16
XINCL_OUT = 0°
YINCL_OUT = 0°
8
ROT_OUT = 0°
9
12
13
POSITIVE
X AXIS TILT
DIRECTION
0° TILT
LEVEL PLANE
Figure 18. Horizontal Incline Angle Orientation
Y AXIS
Figure 19. Vertical Angle Orientation
POSITIVE DIRECTION
90° ≤ ROT_OUT ≤ 180°
4
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5
1
16
0° ≤ XINCL_OUT ≤ 90°
YINCL_OUT = 0°
8
13
9
12
X AXIS
–180° ≤ ROT_OUT ≤ –90°
Figure 16. Single-Axis Tilt Theory Diagram
Figure 17. Dual-Axis Tilt Theory Diagram
Y AXIS
GRAVITY = 1g
GRAVITY = 1g
4
5
1
16
θ
θ
a
x
x
y
XINCL_OUT = 0°
0° ≤ YINCL_OUT ≤ 90°
a
8
a
x
x
θ
θ
9
x
x
12
13
HORIZON
HORIZON
X AXIS