Using smartphone pressure sensors to measure vertical velocities of elevators, stairways, and drones

Abstract

We measure the vertical velocities of elevators, pedestrians climbing stairs, and drones (flying unmanned aerial vehicles), by means of smartphone pressure sensors. The barometric pressure obtained with the smartphone is related to the altitude of the device via the hydrostatic approximation. From the altitude values, vertical velocities are derived. The approximation considered is valid in the first hundred meters of the inner layers of the atmosphere. In addition to pressure, acceleration values were also recorded using the built-in accelerometer. Numerical integration was performed, obtaining both vertical velocity and altitude. We show that data obtained using the pressure sensor is significantly less noisy than that obtained using the accelerometer. Error accumulation is also evident in the numerical integration of the acceleration values. In the proposed experiments, the pressure sensor also outperforms GPS, because this sensor does not receive satellite signals indoors and, in general, the operating frequency is considerably lower than that of the pressure sensor. In the cases in which it is possible, comparison with reference values taken from the architectural plans of buildings validates the results obtained using the pressure sensor. This proposal is ideally performed as an external or outreach activity with students to gain insight about fundamental questions in mechanics, fluids, and thermodynamics.

Advanced tools for smartphone-based experiments: phyphox

“…When the students only record the raw acceleration and pressure data without in-app analysis, as proposed by Monteiro and Martí [18], this is a great experiment to teach data analysis with the not too complicated example of applying the hydrostatic approximation to a large dataset and the optionally more advanced step of numerically deriving the result to obtain the velocity.…”

Linear Quadrupole Magnetic Field Measured with a Smartphone

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Physics, Smartphones and 3D-Print Technology: A Digital-Transition Case Study in Science Education

“…The general potential for smartphones to enhance the classroom experience has been discussed widely (Buck et al, 2013;Langan et al, 2016;Park et al, 2012), including in the present journal (Mammadova, 2018). This has been investigated for some time within the physics education research community: earlier attempts examined handheld devices, such as the Nintendo Wiimote (Hochberg et al, 2016), with the much more versatile smartphone devices (Arribas et al, 2015;Monteiro & Martí, 2016;Tornaría et al, 2014;Vieyra et al, 2015), including tablets (Egri & Szabó, 2015), quickly becoming of greater interest.…”