Integrated Workout Shoe

Peter KatlicAdvisor: Shane Cotter

Current Offerings – Step Counter

Uses internal switch to count “steps”

• Simple design• Small size• Low cost($10-$20)• Accuracy(up to 50%

error rate)• Single user

Current Offerings - GPS

Garmin ForerunnerUses GPS signals to record waypoints distance• Accuracy(1-5% error rate)• Ease of use• Multiple users• Cost($120-$330)• Loss of signal under tree cover• Bulky design

Current Offerings - Accelerometer

Apple Nike + iPodUses accelerometer to measure acceleration distance• Accuracy(up to 10% error rate)• Ease of use• Multiple users• Cost($30) (factoring in iPod($150-$350))• Reliance on iPod

Purpose

• Current offerings are extremes• Create product in between others• Combine benefits of each design

Goals Reached

Produced a device that meets the following criteria:

- Able to be attached to shoe tongue- Part cost of $30- Records time and distance on device- Registers strides with close to 100% accuracy- Measures distance with 90% projected

accuracy- Online workout log

Design Choices• 2-axis vs. 3-axis accelerometer

- no need for z-axis measurements

• Microcontroller (C8051F330)- small form factor- ADC- adequate RAM- sufficient I/O pins

Development Design

• Silicon Labs C8051FX20-TB microcontroller development board

• Analog Devices ADXL321EB-ND accelerometer development board

• Lumex LDQ-M284RI multiplexed display

Final Design (EAGLE)

Circuit Schematic Board Layout

Components

• Serpac CA-10 waterproof enclosure• Silicon Labs C8051F330-GM microcontroller• Analog Devices ADXL321JCP accelerometer• Lumex LDQ-M284RI multiplexed display

Input/Output

Silicon LabsC8051F330

Microcontroller

Analog DevicesADXL321

Accelerometer

Physical Interface:Tactile Switches

Lumex Multiplexed7-Segment Display

Implementation

• Timer0 seconds• Timer3 sampling rate• ADC0 getting input at 100Hz• Port2 display segments• Port4 display digit

Implementation

• Start/stop is pressed timing begins, sampling begins, display time

• Stride is detected calculate stride/second rate and update distance

• Every minute store total distance in array• Start/stop is pressed timing stops, sampling

stops, display distance

Testing – Phase 1

Development Device• Accelerometer data

range• Data capture on 8051• Accurate stride

detection• Simple trials

Axis 0° -90° 90°

Y 1.256V2093

1.206V2015

1.296V2168

X 1.217V 1.172V 1.278V

At 2.441V

Testing – Phase 2

Final Device• Adjust code for new platform• Test walks/runs• Known pace testing• Calibration

Online Workout Log

• PHP with SQL database• Multiple users• Store workouts• Graph workouts• View workouts by date or user

Future Goals/Improvements

• Finish standalone device• Integrate device into shoe• Transfer data to computer and workout log

Questions

Acknowledgements: James Hedrick