BIOSWIM (Body Interface System based on Wearable Integration Monitoring) is a joint multidisciplinary effort involving a number of Portuguese R&D teams. It seeks a pervasive monitoring solution for physiological and biomechanical signals from a swimmer under normal training conditions, both in and out of the water.
A wearable inertial monitoring unit (WIMU) was developed in order to serve as the biomechanical data processing unit of the system. The preliminary version of the WIMU has a commercially available microcontroller (the MSP430) and transceiver set (CC2500), as well as a tri-axial accelerometer and a bi-axial gyroscope serving as sensors
In order to integrate both the accelerometer and the gyroscope into the inertial unit,the Texas Instrument microcontroller based board, eZ430-RF2500, was selected from the many commercially available devices.
The eZ430-RF2500 uses the MSP430F2274 microcontroller which combines a 16-MIPS performance with a 200 Ksps 10-bit analog- to-digital converter (ADC); paired with the CC2500 multi-channel radio-frequency (RF) transceiver, designed for low-power wireless applications. This board offers a combination of hardware and software appropriate for fast prototyping of wireless projects, while offering low-power consumption.
The eZ430-RF2500 can readily use the SimpliciTI wireless communication protocol, a low-power RF (2.4 GHz) protocol aimed for simple and small RF networks (proprietary of Texas Instruments). The SimpliciTI protocol claims to use a minimal set of microcontroller requirements, which in theory lowers the associated system cost.
In this case, the network topology was configured so that the WIMU behaved as an end device (ED), transmitting data packets to a remote or base station. There is room for future expansion, since the protocol permits multiple end devices; therefore multiple WIMUs could be allocated at different body segments, in a truly body sensor network scheme.
Although the device is still at the prototype stage of development, it was capable of providing promising data under in-pool normal conditions. The current version of the WIMU serves as a basis for future implementations that will focus on wearability, energy harvesting, and integration within the BIOSWIM’s project swimsuits.
Testing in and out of the water has provided promising data and contributed to design modifications. These also took into account input from ath- letes, trainers, and physicians. Future work includes the integration of the WIMU within the complete BIOSWIM swimsuit system, complemented by truly integrated EMG and ECG textile sensors and a chemical monitoring unit.
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