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

Viasat MiniDAT™ Battery Sensor Load Cell DC/DC Converter

Data Collected Angle vs. time Torque vs. time  Tx  Ty  Tz Force vs. time:  Fx  Fy  Fz

Data collected from propulsiometer to the PC Force, Torque, & Wheel Angle

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 mV.

MiniDAT™  16-bit resolution  16 single ended or 8 differential analog inputs  8 digital I/O lines  IEEE 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, 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 $ 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

Circuit Diagram

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 b 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