Design and Development of an Accelerometer based Personal Trainer System By Emer Bussmann B.E. Electronic Engineering April 2008

Introduction Exercise is the key to a healthy life Attract interest in running Allowing user to monitor own progress Set achievavle goals Satisfaction

Proposal Maximum benefit from run Portability Low cost Track, record and monitor Achievable goals Speed Distance

Project Overview

Data Source - Accelerometer Measures acceleration forces Capacitance sensor Triaxial Minimum cost, portability and low power consumption Freescale X, Y and Z-Axis Channels Internal Antennae Status LEDs Adjustable output frequency Wireless SparkFun WiTilt v2.5

Accelerometer Preperation Calibration Frequency Positioning

Bluetooth Suitability Wireless Radio Frequency Low power consumption (phone battery) Range

Data Acquisistion Unit -LabVIEW suitability- Visual programming language Libraries – functions Polymorphism Access of instrumentation hardware – Serial Communication VI PDA research

LabVIEW VI Requirements Data Importation using serial VI Data extraction Save data to file

Serial Communication in LabVIEW Front panel for the serial communication VI

Data Extraction

Saving Data to a file

Back end Processing -Matlab Suitability- Numerical computing and programming Implementation of algorithms Import Wizard Plotting Functions

Data Analysis Y- Axis Vertical Impact Z- Axis Anterior-Posterior Integration X- Axis Medio-Lateral

Stride Counter Clear steps Thresholding technique Stride Distance = (Strides)(Stride length) Speed = Distance/Time

Noisy Signals Common signal problem Inaccurate spike count Use distance between spikes Worse during faster run

Integrator Acceleration=> Speed=>Distance Area under curve area 1 is the previous sample area 2 is a triangle formed between the previous sample and the current one Area = Previous Sample + | Sample-Previous Sample | 2

Data Correction Undesirable data (S & I) Calibration (S & I) Filtering (I) Averaging (I)

Undesirable Data Unwanted NaN values Use “ isnan ” to locate Replace with average of nearest neighbours

Calibration Average samples over the range Subtract the offset from the data Major accuacry improvements

Filtering Data Set “ no movement ” states to zero Use thresholding technique and control variable When variable is “ 1 ”, data is “ 0 ”

Averaging data Integration necesity Window of 64 samples

Justification of Stride Counter

Failure of Integrator Unsatisfactory results Noisy Data Purely Graphical information 3 speedSteadyStop inc.

Comparison of algorithms Stride Counter Simple Highly accurate Clean data Limitations due to manual user input requirements Integrator Unsuitable for calculating abilities Graphical indicator of human movement

Problems Encountered Serial Port Issues Programming Issues PDA Issues

Conclusion The proposed aim of designing and developing a portable, cost effective accelerometer based personal trainer system was reached: Accelerometer Data Acquisition Processing algorithms Feedback

Future Work Incorporate PDA Stride Counter automation Energy Algorithm Incorporate ECG

References [1] Information on Triaxial Accelerometers = [2] SparkFun forum [3] Useful bluetooth information [4] Useful background on labVIEW [5] Background information on Matlab [6] Signal processing for estimating energy expenditure of elite athletes using triaxial accelerometers Wixted, A.; Thiel, D.; James, D.; Hahn, A.; Gore, C.; Pyne, D. Sensors, 2005 IEEE Volume, Issue, 30 Oct.-3 Nov Page(s): 4 pp. - Digital Object Identifier /ICSENS [7] Paper on position algorithm implementation Freescale semiconductor application note Implementing Positioning Algorithms Using Accelerometers By: Kurt Seifert and Oscar Camacho [8] Useful Information on Accelerometers sensor.html

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