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