This application note describes the methods and techniques for measuring tilt angles from a low-g 3-axis accelerometer. The LIS331DLH 3-axis digital accelerometer is used as an example in this document. Other 3-axis analog or digital accelerometers may also be applied to the tilt angle measurement procedures described here, depending on their respective specifications.
This document details the procedures for obtaining accurate tilt measurements relative to the local Earth horizontal plane. It utilizes the LIS331DLH 3-axis digital accelerometer as a primary example but notes that other analog or digital accelerometers can be applied depending on their specifications.
The note covers terminology and parameters related to accelerometers, calibration techniques to compensate for non-idealities like cross-axis sensitivity, and the theory of operation for calculating tilt angles using single, dual, and tri-axis sensing methods.
| Power supply range (Vdd) | +2.16 V to +3.6 V |
|---|---|
| Output data rate range (ODR) | 0.5 Hz to 1 kHz |
| Operating temperature range (Top) | -40 °C to +85 °C |
| Full-scale measurement range (FS) | +2 g, +4 g, or +8 g |
| Sensitivity (So) | 1 mg/LSB (typical at 12-bit, +2g FS) |
The LIS331DLH 3-axis digital accelerometer is used as an example.
A +2.0 g range is sufficient because the Earth's gravity is +1 g only.