ECE 480 Design Team 6

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ECE 480Design Team 6

• Small, Lightweight Speed and Distance Sensor
• for Skiers and Snowboarders

Michael Bekkala Michael Blair Michael Carpenter
Matthew Guibord Abhinav Parvataneni Dr. Shanker
Balasubramaniam
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Objective

• Introduction
• Design Requirements
• Proposed Solution
• Testing Results
• Conclusions and Accomplishments

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Introduction

• Living by the numbers
• Measuring and interpreting your performance has
  never been more valuable
• Critical to gain a competitive edge
• Most devices are based on repetitive motion but
  dont apply to skiing or snowboarding
• Nike
• Bicycle speedometer
• Goal Build a speed and distance sensor for
  skiers and snowboarders

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Design Requirements
Operable in Subzero Temperatures
Accurately record speed and distance
Useable in winter apparel
Cost less than 500
Lightweight Less than two pounds
Battery Life greater than 2 hours
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Proposed Solution

• Integration of two major systems
• Global Positioning System (GPS)
• Inertial Navigation System (INS)

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Inertial Navigation System

• Comprised of accelerometers and gyroscopes
• Accelerations
• Angular Velocities
• Requires analog to digital conversion
• Careful calibration is required to achieve high
  accurate readings
• Gives great short-termaccuracy, but errors
  growwith time.

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Global Positioning System

• Gives position in terms of longitude, latitude,
  and altitude
• Determine distance, displacement and speed
• NMEA 0183 communications standard
• Long term reliability, butpoor short term
  accuracy.
• Sampled at 1Hz

http//en.wikipedia.org/wiki/Gps
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Kalman Filtering

• Advanced sensor integration technique
• Uses statistical error measurements to provide a
  better estimate
• Accuracy improves with time
• Can use the estimate to regulate INS errors

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User Interface

• Easily accessible menu displayed on LCD
• Review Performance
• Average and Peak Speed (mph)
• Distance and Displacement (miles)
• Color changing buttons
• Color of button changes depending on their use
• Intuitive color scheme aids usability (ie. Red
  for Stop, Green for Go)

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Menu Hierarchy
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PC Interface

• Upload run data from device
• Can be saved on your PC for performance tracking
  and reference
• Points can be plotted in Google Earth
• Visual representation ofdata using graphs

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PC Interface Example
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Successful Failure

• Reached beyond design requirements with an
  innovative solution
• Unpredicted complexity of INS and Kalman filter
• Hardware implemented, software not ready
• Invaluable knowledge gained through
• Research
• Trial and error
• Despite proposed solution being a successful
  failure
• GPS solution that meets and exceeds design
  requirements
• Extensive user functionality
• Store, retrieve, and manage data all on device or
  through a PC
• Higher data sample rate for greater accuracy
• Rechargeable battery

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Kalman Filter Divergence

• Difficult to troubleshoot due to 1200 lines of
  code
• Unsuccessful in determining cause of divergence
• Poor Initialization might be to blame
• Confident that with more time, root cause could
  be determined

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Testing Results

• Several Trials
• Moving vehicle
• On foot
• Varying speeds and distances
• Peak speed had significant error
• One bad sample results in erroneous reading
• Average speed had reasonable accuracy based on
  number of data points
• Results verified by digital speedometer and
  consumer GPS.

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Conclusions and Accomplishments

• GPS Solution
• Accurate average and peak speeds
• Distance accurate over a large span
• Inaccurate over short spans and slow speeds
• Robust Display Menu
• Allows easy access to data and configuration
  options
• PC Interfacing
• Plot a run on Google Earth with the click of a
  mouse
• Plot speed over time to visualize a run

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Future Considerations

• Printed Circuit Board
• USB Compatibility
• Wireless headset communication via Bluetooth
• Smaller form factor
• INS integrated through Kalman Filtering