Data Interpretation

Understanding Roll, Pitch, Yaw outputs and orientation measurements from OTS sensors

Overview

For most applications, the Roll, Pitch, Yaw outputs should be sufficient.

All outputs are in units of Radians.

Device laid flat is at 0 radians.

Looking along device from rear towards logger, clockwise is positive.

Flat Position: 0 radians
Clockwise Rotation: Positive values
Counterclockwise Rotation: Negative values

Roll measurements are meaningless in vertical applications.

Device laid flat is 0 radians.

Forward pitch is positive.

Flat Position: 0 radians
Forward Pitch: Positive values
Backward Pitch: Negative values

Device pointing up is 0 radians.

Looking onto the top of the lid, clockwise is positive.

Pointing Up: 0 radians
Clockwise Rotation: Positive values
Counterclockwise Rotation: Negative values

Yaw measurements are meaningless in horizontal applications.

As this is a gravitational sensor, only two of these parameters are valid at any one time:

Application Type	Valid Parameters	Meaningless Parameter
Horizontal	Roll, Pitch	Yaw
Vertical	Pitch, Yaw	Roll

The OTS uses a triaxial accelerometer to measure orientation relative to gravity. This means:

In horizontal applications (e.g., railway tracks, bridge decks): The sensor can measure tilt in two directions (Roll and Pitch), but cannot determine rotation around the vertical axis (Yaw) because this axis is aligned with gravity.
In vertical applications (e.g., retaining walls, building facades): The sensor can measure tilt away from vertical in two directions (Pitch and Yaw), but cannot determine rotation around the vertical axis (Roll) because this axis is aligned with gravity.

Always consider your installation orientation when interpreting sensor data. Focus on the two valid parameters for your specific application type.

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