This reminds me of phyphox, a phone app where you can use pretty much all of the phone's sensors as inputs for physical experiments.

https://phyphox.org/

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ncruces an hour ago | parent [-]

That's the app they used:

The phyphox app recorded acceleration and angular velocity at a sampling rate of 100 Hz.

I wonder if they considered using the fact that a roller coaster trajectory is closed loop? That tends to help with calibration, but maybe the devices are nicely factory calibrated to begin with. They get close, but stop short of mentioning it:

The measurements were stopped after the attraction returned to its resting state. This provides reference points at the beginning and the end of the ride where the velocity is zero.

And this gets you real close to building visual inertial oximetry:

Smartphone video recordings were used to correlate specific ride manoeuvres with the recorded data for the roller coaster.

	▲	sam1714 an hour ago \| parent [-]
		>I wonder if they considered using the fact that a roller coaster trajectory is closed loop In terms of the rider, this isn't always the case. Often, the unload station is separate from the load station, basically pipelining. Also for theming; for example, Disney's Space Mountain has the unload and load zones on separate floors. The paper did use the fact that velocity was 0 when they started and ended.