Propulsiometer Instrumented

Wheelchair WheelPrepared 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

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

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

Circuit Diagram

Components (A/D converter)

MAX1868 channel single-ended12-bit resolution Input range: 5VSampling rate of 133kHzOperates at 5V

Components (Multichannel RS232 Drivers/Receivers)

MAX220Chip that made it possible to connect

RS232 and MAX186Data rate =120 kbpsOperates at 5V

Components (5V/Programmable Voltage Regulator)

MAX666Dual mode operation: Fixed +5V or

Adjustable +1.3V to +16VRegulates the power supply to provide

specific voltage to components in the circuit

Operating range +2V to +16.5V

Components (Quadrature Decoder)

US Digital EDAC2Converts 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 BluetoothRange 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