Tuesday, 3 December 2013
Energy-Efficient and Data Synchronized Body Sensor Network for Physical Activity Measurement
Physical activity (PA) increases the fitness level and exercise capacity, helps reduce risk factors such as obesity, diabetes, blood pressure and lipid abnormalities, improves health of the cardiovascular system, and extends life expectancy. Sensory monitoring of PA of human subjects provides an objective means for assessing the energy expenditure of the subjects, thus is of significant interest to the health care and medical communities. Measurement of human physical activity (PA) is important for assessing the health state. A wireless multi-senor integrated measurement system (WIMS) has been designed for measurement of the activity types and intensities of human subjects under free-living conditions. To address challenges posted by the limited battery life and asynchronous data among multiple sensors in the WIMS system, a ZigBee-based wireless platform has been designed, prototyped, and experimentally evaluated. Multi-Data-Packaging and Slot-Data-Synchronization algorithms have been developed improved energy efficiency. Experiments have shown that the design enables continued operation of the wearable system for over 30 hours, with data synchronization error among the various sensor nodes being less than 6 meters. The results demonstrate the effectiveness of the energy-efficient wireless design for human physical activity monitoring.