The effect of whole-body vibration on public transportation passenger performance while typing on smartphones.

This study verified typing performance on smartphones of public transportation passengers using subjective assessments of comfort and difficulty and objective assessments of the number of errors and typing speed. Three frequency values (5, 10, and 15 Hz), two magnitudes (0.6 and 1.2 m/s) and two types of operating systems (Android and IOS) were adopted. Tests without vibration were applied to analyse the residual effect of vibration. The results showed that vibration significantly influences comfort. The higher the frequency, the less errors and the faster the typing speed. In the magnitude analysis, the increase caused a greater number of errors and greater difficulty. In both assessments, the discomfort was proportional to the increase in frequency or magnitude and the number of errors was inversely proportional to the typing speed. Finally, the IOS operating system showed worse comfort when compared to Android, although no significant differences were observed for the objective assessment. Public transportation passengers are exposed to WBV while typing on smartphones. The results showed that vibration influences comfort, the number of errors and the typing speed. Therefore, manufacturers should be aware of the level of vibration that vehicles are exposed to in order to provide more performance to the user. WBV: whole-body vibration; PID: proportional-integral-derivative; RMS: root mean square; HLM: hierarchical linear modeling; OLS: ordinary least squares; STH: seat-to-head.