2023 ASEE Annual Conference & Exposition

Acceleration-based dynamic sensing has been available for many years and numerous researchers have made effective use of the accelerometer available in mobile phones for measuring vibrations at frequencies up to half the sampling rate of the phone. Manufacturers of mobile phones, tablets, and other devices are adding new sensors with each new model creating the potential to expand the engineering laboratory from the confines of university laboratories and into the wider world. Students can collect dynamic measurements with their own mobile phones in addition to, or rather than, expensive laboratory equipment.

In this paper, six methods of vibration sensing are compared to results from a high-precision accelerometer, demonstrating the benefits and drawbacks of various contact and non-contact sensors available on mobile devices, but specifically on the iPhone 12 Pro and later models. Sensors include the accelerometer, magnetometer, RGB camera, and most notably the LiDAR sensor. Non-contact sensing, which is valuable for measuring model structures that might be significantly impacted by the added-mass effect of an attached mobile device, is demonstrated with LiDAR sensing, video-based object tracking, video post-processing, magnetometer, and an app-based implementation of the stroboscopic effect. Contact sensing, which is generally more sensitive, is demonstrated using the on-board accelerometer and compared to a high-precision seismic accelerometer, as well as the non-contact methods. Various mobile apps are cataloged and described for data collection, analysis, and post-processing. These tools represent a variety of phone-based methods for the vibrations or structural dynamics laboratory, allowing students to explore and compare various methods of sensing. The range of applicability of each sensing method is summarized to inform instructors considering phone-based laboratory activities. Instructors can select a method suited to their experiment and learning objectives.