A Wearable Inertial Sensor Node for Body Motion Analysis

A wearable wireless inertial sensor node for body motion analysis is designed and implemented. A triaxial accelerometer, a biaxial gyroscope, and a yaw rate gyroscope are employed to sense the accelerations and angular rates of the object attached. These three ICs, a wireless mote, the power circuit, and a modified printed inverted-F antenna are integrated on a four-layer printed circuit board. To achieve the compact size for comfortable wearing, the printed antenna is deliberately designed as small as possible, while maintaining a reasonable antenna performance. The proposed inertial sensor node is also easily adaptable to applications with different power requirements because of the consideration of the periodic and moving-event wakeup in the software design. The static characteristics and Allan deviations of the implemented node are measured and analyzed. The false alarm rate of a moving detection based on Bayes rule is presented and a threshold is suggested. Finally, the raw data of several body motions are measured and those behaviors are observed apparently. The proposed inertial sensor node is compact and easily wearable; hence, it is feasible to be applied to the body motion analysis.