Smartphone Sensor-Based Experiments for Characterizing First and Second Order Systems

The widespread use of smartphones along with the presence of multiple sensors inside renders them ideal tools for teaching experiments. User-friendly applications are available that make the process of accessing and logging sensor data simple. This combination of accessibility and compactness have made smartphones a viable alternative to complex data acquisition systems (DAQs), provided that the sampling rate of the experiments lie within the operational capabilities of the smartphone. To demonstrate the utility of smartphones in data acquisition, two undergraduate dynamics experiments using smartphone sensors are presented. These experiments study the response of a first order and a second order system subjected to damping. The first experiment analyzes the effect of damping on the decay response of a ceiling fan starting from a steady-state angular speed. Analysis of the gyroscope sensor's data has been performed to determine the appropriate damping model. The response of the fan with two additional surfaces to provide increased damping has also been investigated. The second order system investigates the vibration response of a cantilever. The smartphone's accelerometer data as well as the displacement data derived from videos using image processing are compared with the results of a laser displacement sensor. The effect of both viscous and Coulomb damping are analyzed.