Body Sensor Layer

Each custom-built motion sensor has a triaxial accelerometer and a biaxial gyroscope, which is attached to a Tmote Sky network mote. Each node is currently powered by a Li-ion battery housed between the two sensor boards. The current hardware design of the sensor contributes certain amounts of measurement error.

The accelerometers typically require some calibration in the form of a linear correction, as sensor output under 1g may be shifted up to 15% in some sensors. It is also worth noting that the gyroscopes produce an indication of rotation under straight line motions. Fortunately these systematic errors appear to be consistent across experiments for a given sensor board. However, without calibration to correct them, the errors may affect the action recognition if different sets of sensors are used interchangeably in the experiment.

	Body Sensor Layer
	Each custom-built motion sensor has a triaxial accelerometer and a biaxial gyroscope, which is attached to a Tmote Sky network mote. Each node is currently powered by a Li-ion battery housed between the two sensor boards. The current hardware design of the sensor contributes certain amounts of measurement error. The accelerometers typically require some calibration in the form of a linear correction, as sensor output under 1g may be shifted up to 15% in some sensors. It is also worth noting that the gyroscopes produce an indication of rotation under straight line motions. Fortunately these systematic errors appear to be consistent across experiments for a given sensor board. However, without calibration to correct them, the errors may affect the action recognition if different sets of sensors are used interchangeably in the experiment.

	The Wisepla biosensor board was developed in Tampere University of Technology, Finland, which is also attached to a Tmote board. The sensor node integrates three types of sensors: An electrical impedance pneumography (EIP). An electrocardiogram (ECG). A triaxial accerometer. The physiological parameters that can be derived from EIP include the tidal volume, ventilation, respiration frequency, and inspiration/expiration time. The parameters that can be derived from ECG include the heart rate and heart rate variability. [A demonstration video of the biosensor is available]

	Distributed Action Recognition via Motion Sensors
	This technique is patent pending by the UC Berkeley IP offices. For licensing, please contact: [Office of Intellectual Property & Industry Research Alliances] Author: Allen Yang (c) UC Berkeley, 2008.