This thesis is about motion registration for Active Music applications, where motions is used to generate sound and music in real-time.
Different motion capture systems have been implemented and tested in this master thesis. These systems consist of sensor elements, which wirelessly transfers motion data to a receiver element. The sensor elements consist of a microcontroller, accelerometers and a radio transceiver. The receiver element consists of a radio receiver connected to a computer for real time sound synthesis. The wireless transmission between the sensor elements and the receiver element is based on the low rate IEEE 802.15.4/Zigbee standard. Transmission delays have to be unnoticeable for users of Active Music applications. Various tests considering transmission delays have been conducted in order to find advantages and disadvantages of the implemented motion capture systems. Limitations such as physical size of the systems and processing capabilities within the systems have been looked into.
The first implemented system is based on a star topology. This implementation has an upper limit of 3 sensor elements for each receiver element. A more theoretical calculation shows the possibility for 6 sensor elements in a more effective implementation. The second implemented system is based on a peer-to-peer topology, where one sensor element reads multiple accelerometers and transmits these data to one receiver element. This implementation has an upper limit on 5 sensors inside one sensor element.
Sensor data processing can be done in either the receiver element or in the sensor element. For various reasons it can be reasonable to implement some sensor data processing in the sensor element. This thesis looked into how much processing it is suitable to carry out inside these sensor elements. The star based motion capture system had advantages compared the peer-to-peer system when performing processing within the sensor elements.