Why are my MATLAB Mobile orientation measurements unstable when my mobile device points vertically up?

When I hold my phone in a "horizontal" configuration (screen facing me, top of phone to the left/right), orientation measurements are as expected. However, when I hold my phone in a "vertical" configuration (screen facing me, top of phone to ceiling), my Y-axis orientation measurements are steady but my X-axis and Z-axis orientation measurements are unstable and fluctuate significantly.

Are the fluctuating measurements expected for a "vertical" configuration? I have been able to reproduce this behaviour on various Android and iOS mobile devices.

Answer 1

[MathWorks Support Team]

Fluctuating orientation measurements are expected when a mobile device's pitch measurement approaches 90°. They are a result of the "Gimbal Lock" phenomenon.

The Gimbal Lock occurs at a singularity point in the orientation measurement configuration: when the pitch of the mobile device is 90°, changes in yaw are indistinguishable from changes in roll, i.e. the orientation is not fully defined. Consequently, azimuth and roll measurements become unstable as the pitch approaches the singularity at 90°.