Human Posture Measurement System Brandon Ngai Lawrence Wong Josephine Wong [email_address] Team Personnel: Contact Email:
Overview <ul><li>Overview of project </li></ul><ul><li>Functional specifications </li></ul><ul><li>System design </li></ul...
The Objective <ul><li>To develop a portable human monitoring device that tracks and records the movement of different part...
The Motivation <ul><li>Motivated by the research needs of Dr. Steve Robinovich (SFU) and Dr. David Rempel (U of California...
Intended Applications <ul><li>Study of the loss of balance and falling in the elderly </li></ul><ul><ul><li>Prevention of ...
Current Solutions <ul><li>Similar devices are commercially-available </li></ul><ul><ul><li>Data-loggers </li></ul></ul><ul...
MicroStrain Virtual Corset <ul><li>Measures the angle of inclination of the trunk of the body </li></ul><ul><li>Operates a...
MicroStrain Virtual Corset <ul><li>Limitations include: </li></ul><ul><ul><li>High cost </li></ul></ul><ul><ul><ul><li>$1,...
Motion-Capture System <ul><li>Markers are mounted on the subject </li></ul><ul><li>Video cameras are used to track the mar...
Motion-Capture System <ul><li>Limitations include: </li></ul><ul><ul><li>High cost </li></ul></ul><ul><ul><li>Difficult to...
The microSense Solution <ul><li>Pager-sized sensor units that operate autonomously from other units </li></ul><ul><li>Meas...
The Device In Action
Functional Specifications <ul><li>0.5  degree  resolution </li></ul><ul><li>Measures 360 ° of rotation about the x-axis an...
Device Limitations <ul><li>Insensitive to rotation about the vertical axis </li></ul><ul><ul><li>Sensor measures changes i...
System Overview <ul><li>Uses two micro-electrical system (MEMS) accelerometers to measure the angles of inclination </li><...
System Block Diagram
Device Schematic
Inclination Sensors <ul><li>2 x Analog Devices ADXL203E MEMS accelerometers  </li></ul><ul><li>Mounted perpendicular to ea...
Data Acquisition <ul><li>Continuous data acquisition at 32 samples per second </li></ul><ul><li>Sensors provide analog out...
Flash Memory <ul><li>Toshiba TC58DVG20A1 1-Gbit NAND flash memory </li></ul><ul><li>Holds 128Mb of data </li></ul><ul><li>...
Data Structure <ul><li>2 bytes per sample </li></ul>
Data Storage <ul><li>A 1-Gbit chip can store up to 12 days of data at 32 samples per second </li></ul><ul><li>2-Gbit NAND ...
Data Transmission <ul><li>Data is transmitted to a computer via an USB cable </li></ul><ul><li>The computer automatically ...
Data Conversion <ul><li>Angle measurements are calculated from the raw data by the computer </li></ul>
Graphical User Interface <ul><li>Windows-based GUI </li></ul><ul><li>Allows user to establish and terminate data communica...
Data Output <ul><li>System outputs a comma separated value (CSV) file </li></ul><ul><li>Lists the angles of inclination wi...
Design Challenges <ul><li>Component identification and acquisition </li></ul><ul><ul><li>Long shipping delays </li></ul></...
Testing Protocol <ul><li>Real-time testing </li></ul><ul><ul><li>Used to verify sensor accuracy and sensor-to-microcontrol...
Real-Time Testing <ul><li>Device is connected to a computer via USB </li></ul><ul><li>Enables sensor calibration </li></ul...
System Testing <ul><li>Need for extensive system testing to determine the accuracy and reliability of the device </li></ul>
Testing Challenges <ul><li>Difficult to test each system module independently of other modules </li></ul><ul><li>Heavily r...
Device Characteristics
Device Characteristics
Power Consumption <ul><li>Prototype is powered by 3 AA batteries </li></ul><ul><li>Standby mode </li></ul><ul><ul><li>13mA...
Current Status <ul><li>Device can measure, record, and transmit data </li></ul><ul><li>Can also operate in real-time mode ...
Future Improvements <ul><li>Final prototype will require 2 AA batteries </li></ul><ul><li>Users will be able to mark key e...
Questions?
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msmdemo.ppt

  1. 1. Human Posture Measurement System Brandon Ngai Lawrence Wong Josephine Wong [email_address] Team Personnel: Contact Email:
  2. 2. Overview <ul><li>Overview of project </li></ul><ul><li>Functional specifications </li></ul><ul><li>System design </li></ul><ul><li>System testing </li></ul><ul><li>Current progress </li></ul><ul><li>Future improvements </li></ul>
  3. 3. The Objective <ul><li>To develop a portable human monitoring device that tracks and records the movement of different parts of the body </li></ul><ul><li>Should combine motion-sensing, data-logging, and data-transmission capabilities </li></ul>
  4. 4. The Motivation <ul><li>Motivated by the research needs of Dr. Steve Robinovich (SFU) and Dr. David Rempel (U of California) </li></ul><ul><li>Limited number of tools available for human movement and injury prevention research </li></ul>
  5. 5. Intended Applications <ul><li>Study of the loss of balance and falling in the elderly </li></ul><ul><ul><li>Prevention of hip-fractures and possible life-threatening injuries </li></ul></ul><ul><li>Examination of the causes of work-related injuries in construction workers </li></ul><ul><ul><li>Prevention of carpal tunnel syndrome </li></ul></ul>
  6. 6. Current Solutions <ul><li>Similar devices are commercially-available </li></ul><ul><ul><li>Data-loggers </li></ul></ul><ul><ul><ul><li>MicroStrain Virtual Corset </li></ul></ul></ul><ul><ul><li>Motion-capture system </li></ul></ul>
  7. 7. MicroStrain Virtual Corset <ul><li>Measures the angle of inclination of the trunk of the body </li></ul><ul><li>Operates at 900 µA at 3.6V </li></ul><ul><li>Commonly used in human movement research studies </li></ul>
  8. 8. MicroStrain Virtual Corset <ul><li>Limitations include: </li></ul><ul><ul><li>High cost </li></ul></ul><ul><ul><ul><li>$1,000US per unit </li></ul></ul></ul><ul><ul><li>Uses specialized batteries </li></ul></ul><ul><ul><li>Limited measurement range </li></ul></ul><ul><ul><ul><li>Reduced resolution between 85 ° and 90° </li></ul></ul></ul>
  9. 9. Motion-Capture System <ul><li>Markers are mounted on the subject </li></ul><ul><li>Video cameras are used to track the markers </li></ul><ul><li>Requires a minimum of 3 cameras </li></ul>
  10. 10. Motion-Capture System <ul><li>Limitations include: </li></ul><ul><ul><li>High cost </li></ul></ul><ul><ul><li>Difficult to transport </li></ul></ul><ul><ul><li>Mostly limited to lab settings </li></ul></ul><ul><ul><li>Complex software packages are required to extract the data from the video feed </li></ul></ul>
  11. 11. The microSense Solution <ul><li>Pager-sized sensor units that operate autonomously from other units </li></ul><ul><li>Measuring the angle of inclination of a body segment in three-dimensional space (with respect to gravity) </li></ul><ul><li>Stores acquired data in internal flash memory for up to 12 days </li></ul><ul><li>Uploads data to a computer via USB </li></ul>
  12. 12. The Device In Action
  13. 13. Functional Specifications <ul><li>0.5 degree resolution </li></ul><ul><li>Measures 360 ° of rotation about the x-axis and y-axis </li></ul><ul><li>Acquires data at 32 samples per second </li></ul><ul><li>Stores up to 1 Gbit of data (12 days) </li></ul><ul><li>Powered by 2 AA batteries (final design) </li></ul>
  14. 14. Device Limitations <ul><li>Insensitive to rotation about the vertical axis </li></ul><ul><ul><li>Sensor measures changes in orientation with respect to gravity </li></ul></ul><ul><ul><li>Unavoidable with the chosen sensor technology </li></ul></ul>
  15. 15. System Overview <ul><li>Uses two micro-electrical system (MEMS) accelerometers to measure the angles of inclination </li></ul><ul><li>Controlled by a PIC18 microcontroller with built-in USB capabilities </li></ul><ul><li>Raw data is stored in 1 Gbit flash memory chip </li></ul><ul><li>Angle outputs are calculated by the computer terminal </li></ul>
  16. 16. System Block Diagram
  17. 17. Device Schematic
  18. 18. Inclination Sensors <ul><li>2 x Analog Devices ADXL203E MEMS accelerometers </li></ul><ul><li>Mounted perpendicular to each other </li></ul><ul><li>Most sensitive when the measurement axis is perpendicular to gravity </li></ul>
  19. 19. Data Acquisition <ul><li>Continuous data acquisition at 32 samples per second </li></ul><ul><li>Sensors provide analog outputs </li></ul><ul><li>Digitalized using the 10-bit ADC on the PIC18 microcontroller </li></ul><ul><li>Non-linear relationship between sensor output and angle of inclination </li></ul><ul><ul><li>Calculated using arcsin function </li></ul></ul>
  20. 20. Flash Memory <ul><li>Toshiba TC58DVG20A1 1-Gbit NAND flash memory </li></ul><ul><li>Holds 128Mb of data </li></ul><ul><li>Durable and reliable </li></ul><ul><li>Interfaces with the PIC18 microcontroller via 8 address/data lines and 7 control lines </li></ul>
  21. 21. Data Structure <ul><li>2 bytes per sample </li></ul>
  22. 22. Data Storage <ul><li>A 1-Gbit chip can store up to 12 days of data at 32 samples per second </li></ul><ul><li>2-Gbit NAND flash memory chips are also available </li></ul><ul><ul><li>More difficult to acquire </li></ul></ul>
  23. 23. Data Transmission <ul><li>Data is transmitted to a computer via an USB cable </li></ul><ul><li>The computer automatically recognizes the sensor device </li></ul><ul><li>Data transmission begins at the user’s command </li></ul><ul><ul><li>Graphical user interface </li></ul></ul>
  24. 24. Data Conversion <ul><li>Angle measurements are calculated from the raw data by the computer </li></ul>
  25. 25. Graphical User Interface <ul><li>Windows-based GUI </li></ul><ul><li>Allows user to establish and terminate data communications with the sensor units </li></ul><ul><li>Allows user to initiate data transfer </li></ul>
  26. 26. Data Output <ul><li>System outputs a comma separated value (CSV) file </li></ul><ul><li>Lists the angles of inclination with respect to the x-axis and y-axis at each sampling time </li></ul><ul><li>Readable using Microsoft Excel </li></ul>
  27. 27. Design Challenges <ul><li>Component identification and acquisition </li></ul><ul><ul><li>Long shipping delays </li></ul></ul><ul><ul><li>Need for adapter boards for small packages </li></ul></ul><ul><li>Subdividing the system </li></ul><ul><ul><li>Difficulties in integrating the system modules </li></ul></ul>
  28. 28. Testing Protocol <ul><li>Real-time testing </li></ul><ul><ul><li>Used to verify sensor accuracy and sensor-to-microcontroller communications </li></ul></ul><ul><li>System testing </li></ul><ul><ul><li>Required to verify data storage and retrieval </li></ul></ul><ul><ul><li>Ensures the proper integration of the system </li></ul></ul>
  29. 29. Real-Time Testing <ul><li>Device is connected to a computer via USB </li></ul><ul><li>Enables sensor calibration </li></ul><ul><li>Device outputs are compared to a 1-axis digital level for accuracy </li></ul>
  30. 30. System Testing <ul><li>Need for extensive system testing to determine the accuracy and reliability of the device </li></ul>
  31. 31. Testing Challenges <ul><li>Difficult to test each system module independently of other modules </li></ul><ul><li>Heavily reliant on USB-to-PC interface during testing </li></ul><ul><li>Difficult to verify timer operation </li></ul><ul><li>Hard to pinpoint problems and debug the system </li></ul>
  32. 32. Device Characteristics
  33. 33. Device Characteristics
  34. 34. Power Consumption <ul><li>Prototype is powered by 3 AA batteries </li></ul><ul><li>Standby mode </li></ul><ul><ul><li>13mA of current </li></ul></ul><ul><li>Data acquisition mode </li></ul><ul><ul><li>45mA of current </li></ul></ul><ul><li>Data transmission mode (USB connected) </li></ul><ul><ul><li>50mA of current </li></ul></ul><ul><li>Need to minimize power consumption </li></ul>
  35. 35. Current Status <ul><li>Device can measure, record, and transmit data </li></ul><ul><li>Can also operate in real-time mode (for system testing) </li></ul><ul><li>Currently developing a time-stamping algorithm (to synchronize data from multiple sensors) </li></ul><ul><li>Need to test the system for accuracy and reliability </li></ul>
  36. 36. Future Improvements <ul><li>Final prototype will require 2 AA batteries </li></ul><ul><li>Users will be able to mark key events in the data with the press of a button </li></ul><ul><li>May implement wireless data transmission </li></ul>
  37. 37. Questions?
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