Wearable Wireless Nodes - Each of the wearable nodes is capable of sampling at 1000Hz (samples per second) and can store up to 10 seconds worth of sensor data. The core that controls each node is an MSP430 microcontroller from Texas Instruments running at 8MHz and having 116kB of flash memory. It polls the sensors and logs the raw sensor data to its flash memory. It recieves commands and transmits its gathered data via a 2.4GHz radio from Nordic Semiconductor. These nodes were orignally built by Ryan Aylward for his Sensemble project and have been heavily modified for application in sports.

 

Basestation - The basestation is what allows a network of wireless nodes to communicate with other devices, such as a PC, laptop or PDA, It consists of an 8051 series microcontroller from Silicon Labs and the same 2.4GHz radio from Nordic Semiconductor. The microcontroller has a built in USB Controller which is what enables generic communication with other devices. The basestation sends beacons to all nodes in the network at 100Hz (times per second) in order to maintain timing synchronization. Other than this all command and control of the network is done via a comand protocol in which the basestation receives commands via the USB from the host device and sends them out to the network.

Sample System Architecture - Pictured right is a typical configuration that was used on a baseball pitcher. A laptop computer running sportSemble software sens commands via the USB interface to the basestation. The basestation then broadcasts the commands to the wireless nodes. Each node is placed on the body using various means (velcro, tape, sewn into uniform). Data is gathered on the nodes as the pitcher is throwing a baseball. This data is wirelessly transmitted to the basestation and then from teh basestation to the laptop. The wireless and wired protocols are built and designed to ensure data integrity so that no data is lost. Once on the laptop or PC the data can be further analyzed using custom software.

Precursors to sportSemble - sportSemble builds on hardware designed by Ryan Aylward and Dan Lovell that was known as the Sensemble project. Sensemble is a realtime, high-bandwidth, compact wearable sensing platform designed for interactive dance ensembles.