ADIS16209

Preliminary Technical Data

Rev. PrA | Page 10 of 16

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 both dynamic forces associated with acceleration and static

forces, such as gravity.

Figure 19 and Figure 20 illustrate how the accelerometer

responds to gravity, according to its orientation, with respect

to gravity. Figure 19 displays the configuration for the incline

angle outputs and Figure 20 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.

GRAVITY = 1g

HORIZON

Figure 19. Single-Axis Tilt Theory Diagram

HORIZON

GRAVITY = 1g

Figure 20. Dual-Axis Tilt Theory Diagram