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Propulsiometer Instrumented Wheelchair Wheel. Prepared by: Seri Mustaza (BME) Siti Nor Wahida Fauzi (BME) Ahmad Shahir Ismail (EECE) Hafizul Anwar Raduan (CompE) Advisor: Dr. W Mark Richter (PhD, Director of Research and Development, MAXmobility). MAXmobility.
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Propulsiometer Instrumented Wheelchair Wheel Prepared by: Seri Mustaza (BME) Siti Nor Wahida Fauzi (BME) Ahmad Shahir Ismail (EECE) Hafizul Anwar Raduan (CompE) Advisor: Dr. W Mark Richter (PhD, Director of Research and Development, MAXmobility)
MAXmobility • Accessible wheelchair treadmill • Basically, working with ergonomic wheelchair: • Propulsiometer instrumented wheelchair wheel • Transfer friendly wheelchair • Variable Compliance Hand-Rim Prototype (VCHP) • Effective ways to propel the wheel
Propulsiometer • To access the load applied by manual wheelchair user. • Consist of DAQ, load cell, wireless transmitter, battery, DC/DC converter, sensor. • Located on tubular hoop that can be mounted on different sizes of wheelchair’s wheel. • Mainly use as research tool in lab. Ex: Calculating metabolic rate
Propulsiometer Battery Viasat MiniDAT™ Sensor DC/DC Converter Load Cell
Data Collected • Angle vs. time • Torque vs. time • Tx • Ty • Tz • Force vs. time: • Fx • Fy • Fz
Force, Torque, & Wheel Angle Data collected from propulsiometer to the PC
Load Cell signals • Each of the 6 signals ranges from -5 V to +5 V • 12 bit A/D converter • Resolution = range/# of states (10/4096) • For each step size, would equals to 2.4412mV.
MiniDAT™ • MiniDAT™ • 16-bit resolution • 16 single ended or 8 differential analog inputs • 8 digital I/O lines • IEEE 802.11 wireless LAN • Uses 15V DC voltage • 7.9 x 4.2 x 1.42 inches (LWH) • Weight = 1.5lb • Cost = $4,625.00
Problem • MiniDAT is no longer available • Bulky • Uses too much power • Cost = $4,625.00 • Have to wait about 20 minutes to reboot
Main GOAL • Replacing MiniDAT™
Specific Goals • Size: 4 x 4 x 0.5 inches (LWH) • Weight: ~0.25lb • Cost: less than $1000.00 • Low power consumption
Target Specification • 7 analog channels and 1 digital channel • A/D with 12 bit resolution • 1 quadrature encoder input • Wireless capability • Sampling rate of at least 10 kHz • Accepts voltage signal of -5/+5 volts • Power consumption ~5 watts • Small and compact
Components(A/D converter) • MAX186 • 8 channel single-ended • 12-bit resolution • Input range: 5V • Sampling rate of 133kHz • Operates at 5V
Components(Multichannel RS232 Drivers/Receivers) • MAX220 • Chip that made it possible to connect RS232 and MAX186 • Data rate =120 kbps • Operates at 5V
Components(5V/Programmable Voltage Regulator) • MAX666 • Dual mode operation: Fixed +5V or Adjustable +1.3V to +16V • Regulates the power supply to provide specific voltage to components in the circuit • Operating range +2V to +16.5V
Components(Quadrature Decoder) • US Digital EDAC2 • Converts incremental encoder into analog position sensor • 12-bit analog resolution • Output range: 10V • Operates at 12V
Components(Wireless Serial Adapter) • Socket Cordless Serial Adapter (CSA) • Uses RS232 (Serial Port) • Has a class 2 Bluetooth • Range up to 10m • Simple plug, install, and play
If all else fails… • Current solution is the most optimum (cost, size, etc) • There is slight chance that it would not work • So, we formed a backup plan
The backup plan • Consists of two pre-packaged components and one software package: • Sensoray Model 526 • Airborne Embedded Wireless Bridge, Ethernet to Wireless LAN (Module) • xPC Target 2.9
Sensoray Model 526 • PC/104 Multifunctional I/O board • Four 24-bit quadrature encoder inputs • Eight 16-bits analog inputs • Approximately 4’’x4’’
Airborne Ethernet to Wireless • Add wireless LAN connectivity to Model 526 • IEEE 802.11b compliant • Very small footprint, less than 2’’x2’’
xPC Target 2.9 from Mathworks • Provides high-performance, host-target prototyping environment • Makes it easier to program Model 526
Current Status • Finalizing the components needed for current solution • Buying the components • Building the solution