The measurement of sport specific performance characteristics is an important part of an athletes training and preparation for competition. Thus automated measurement, extraction and analysis of performance measures is desired and addressed in this paper. A tri-axial accelerometer based system was located on the lower back or swimmers to record acceleration profiles. The accelerometer system contained two ADXL202 bi-axial accelerometers positioned perpendicular to one another, and can store over 6 hours of data at 150Hz per channel using internal flash memory. The simultaneous collection of video and electronics touch pad timing was used to validate the algorithm results. Using the tri-axial accelerometer data, algorithms have been developed to derive lap times and stroke count. Comparison against electronic touch pad timing against accelerometer lap times has produced results with a typical error of better than ±0.5 seconds. Video comparison of the stroke count algorithm for freestyle also produced results with an average error of ±1 stroke. The developed algorithms have a higher level of reliability compared to hand timed and counted date that is commonly used during training.
Integrated smart sensors are quickly becoming an industry norm and often require multi-stage, multi-skilled design. This paper describes the fabrication of a temperature compensated light sensor using only a basic fabrication laboratory. A complete description of how to build the sensing elements, support electronics and communications is described and test results are presented. The construction of a light sensor using a shottkey barrier diode between the nickel and n-type silicon has been previously described by the authors. In this two such sensors are used as active and passive sensor elements to compensate for temperature effects. The outputs from each are differentially amplified, conditioned and buffered using an LM324 die to provide a temperature compensated output. Further reduction in size is possible when the temperature sensors are mounted front to back on a single silicon substrate and coupled directly to the LM324 die. External communications are only power, ground and an analogue signal.
Triaxial accelerometers have been used to measure human movement parameters in swimming. Interpretation of data is difficult due to interference sources including interaction of external bodies. In this investigation the authors developed a model to simulate the physical movement of the lower back. Theoretical accelerometery outputs were derived thus giving an ideal, or noiseless dataset.
An experimental data collection apparatus was developed by adapting a system to the aquatic environment for investigation of swimming. Model data was compared against recorded data and showed strong correlation. Comparison of recorded and modeled data can be used to identify changes in body movement, this is especially useful when cyclic patterns are present in the activity. Strong correlations between data sets allowed development of signal processing algorithms for swimming stroke analysis using first the pure noiseless data set which were then applied to performance data. Video analysis was also used to validate study results and has shown potential to provide acceptable results.
A modular self-contained modular platform is described, for easy integration with micro sensors and other sensor elements. The platform is designed to be physically robust and suitable for harsh environments. The platform features switch able power modes, signal processing capabilities and extensive I/O for sensor and external device communications, data download and transmission. The modular design allows flexible implementation of required functionality depending on the particular application and also provides flexibility for packaging solutions. Two practical applications of the platform are presented to demonstrate its use. Firstly a variety of human exercise activities are investigated using accelerometers. Secondly a weather station made up of environmental sensors using off the shelf and prototype sensors is described. Both of these applications differ greatly in their operational requirements. These implementations demonstrate the adaptability of the platform for different applications.