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 Located on tubular hoop that can be mounted on different sizes of wheelchair’s wheel. To access the load applied by manual wheelchair user. Consist of DAQ, load cell, wireless transmitter, battery, DC/DC converter, sensor.

Propulsiometer Viasat MiniDAT™ Battery Sensor Load Cell DC/DC Converter

Propulsiometer

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, Moments & 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.

Problem MiniDAT is no longer available Bulky Use too much power Cost = $4,625.00

Specific Goals Size: 2 x 2 x 0.5 inches (LWH) Weight: ~0.25lb Cost: less than $

Target Specification 6 analog channels A/D converter with 12-bit resolution 1 quadrature encoder input Wireless capability Sampling rate of at least 10 kHz Accepts voltage signal of ± 5 volts Low power consumption (15 watts max) Small and compact (5 x 5 inches max)

1 st Approach Sensoray Model 526 Pros:  Meet all requirements  Built-in Linux/Windows OS Cons:  Does not support LabVIEW  Expensive ~$1500

Four 24-bit quadrature encoder inputs Eight 16-bit analog ±10V differential inputs 10kHz sampling rate Approximately 4 x 4 inches Single supply (5V, 5mA) input power Model 526

2 nd Approach Sheldon SI-MOD68xx Pros:  Meet all requirements  Built-in Linux/Windows and support the LabVIEW Cons:  Too expensive ~$2500

Up to 64SE/32DE Analog Inputs 16-bit resolution, ±10V 100khz/250khz sampling Two 32-bit quadrature inputs 7 watts in maximum configuration Approximately 4 x 4 inches SI-MOD68xx

3 rd Approach Multi-companies Connect the quadrature decoder, A/D converter and wireless transceiver onto one single PCB board Pros:  Optimum functionality  Low cost Cons:  Finding the right components

Solution 3 rd approach Decision base on:  Low cost  Flexibility in combining the components  No unnecessary functions

Current status Design the circuit Finalize & buy the components for the circuit

Components (A/D converter) MAX186  8 channel single-ended  12-bit resolution  Input range: 5V  Sampling rate of 133kHz  Operates at 5V

Components (Quadrature decoder) GEN  22-bit Up/Down counter  5V or 3.3V I/O capability  Max input speed of 10MHz  Operates at 5V

Components (2.4 GHz wireless transceiver) Nordic Semiconductor nRF2401  Data rate up to 1MHz  Operating voltage: 3V  Built-in antenna  Size: 1.44 x 0.79 x 0.9 inches (LWH)

Components ( 5V Voltage Regulator) National Semiconductor LM2937  Max input voltage: 26V  Output voltage: 5V  Current output: 10mA (max)

Circuit example

Work Contribution