Measurements of Pedestrian’s load Using Smartphones

This paper explores the application of smartphones for human-induced loads measurements. Preliminary tests were carried out to select proper smartphones and data acquisition software. Shaking table tests were then conducted on selected smartphones to measure sinusoidal waves of various frequencies, sinusoidal sweep waves and earthquake waves. Comparison between the smartphones’ measurements and real inputs showed that the smartphones used in this study gave reliable measurements for harmonic waves in both time and frequency domains. For complex wave, however, the smartphones’ measurements should be used with caution. Subsequently, the motion capture technology was employed to explore two key technical issues for the application of smartphones for human-induced loads measurements. Experimental results on individual’s jumping, walking and bouncing activity demonstrated that the installation manner and angel correction had a significant effect on the measurement accuracy of smartphone. When the phones were securely fastened and the original data was corrected to right angles, the smartphones’ measurements agreed well the references. Encouraged by the above experimental validation results, the smartphones were attached to a moving person to measure the acceleration near the center-of-mass of his/her body. The human-induced loads were then reconstructed by the acceleration measurements in conjunction with a biomechanical model. Satisfactory agreements between the reconstructed forces and that measured by force plate were observed for jumping and bouncing load, clearly demonstrating the capability of the smartphones for human-induced loads measurements.