Victor Martinus Gerardus Van Acht

Miniature Wireless Inertial Sensor for Measuring Human Motions

A sensor system for measuring human motions is presented. The system consists of a number of miniature wireless inertial sensors that are attached to limbs of a person, and a PC with a wireless receiver that interprets and presents the measurement data. Each of the sensors measures 3D- acceleration, 3D-magnetization (earth magnetic field) and 3D- angular speed (gyroscopes). The data is transmitted via a proprietary protocol on an 802.15.4 radio. The angular accuracy of the calibrated system was found to be better than 3 degrees. The system is currently being applied in a pilot trial for motor rehabilitation of stroke patients.

Considerations for Synchronization in Body Area Networks for Human Activity Monitoring

In this paper, we highlight considerations for synchronization issues in body area networks. Requirements for the synchronization accuracy in body area networks depend on the application at hand. Synchronization may be needed for power management, sample ordering, calculation of stimulus responses and for sensor fusion. This paper provides a theoretical exercise to help understand the accuracy required for typical human motion sensing. It gives an overview of various synchronisation strategies used and implemented in prototype systems. Lessons learnt from practical implementations using Bluetooth, an IEEE 802.15.4 proprietary network and Nanonet are presented to illustrate the principles involved. The discussion provides some considerations and the requirements for typical WBAN applications.