Comparison and characterization of Android-based fall detection systems

Abstract

Falls are a foremost source of injuries and hospitalization for seniors. The adoption of automatic fall detection mechanisms can noticeably reduce the response time of the medical staff or caregivers when a fall takes place. Smartphones are being increasingly proposed as wearable, cost-effective and not-intrusive systems for fall detection. The exploitation of smartphones' potential (and in particular, the Android Operating System) can benefit from the wide implantation, the growing computational capabilities and the diversity of communication interfaces and embedded sensors of these personal devices. After revising the state-of-the-art on this matter, this study develops an experimental testbed to assess the performance of different fall detection algorithms that ground their decisions on the analysis of the inertial data registered by the accelerometer of the smartphone. Results obtained in a real testbed with diverse individuals indicate that the accuracy of the accelerometry-based techniques to identify the falls depends strongly on the fall pattern. The performed tests also show the difficulty to set detection acceleration thresholds that allow achieving a good trade-off between false negatives (falls that remain unnoticed) and false positives (conventional movements that are erroneously classified as falls). In any case, the study of the evolution of the battery drain reveals that the extra power consumption introduced by the Android monitoring applications cannot be neglected when evaluating the autonomy and even the viability of fall detection systems.

Figure 1.

MonEPDem System architecture.

Figure 2.

Working procedure of the system.

Figure 3.

Snapshots of the User Interface (UI).

Figure 4.

Relationship between the percentages of False Negatives (FN) and False Positives (FP) for different values of the detection threshold Th_tt when Th_ct is set to a fixed value. Each point in the graph corresponds to the utilization of a different value of the Th_tt threshold.

Figure 5.

Estimation of energy consumption in the HTC Desire X phone.

Figure 6.

Estimation of energy consumption in the HTC Sensation XE phone.