Propulsiometer Instrumented Wheelchair Wheel Prepared by: Seri Mustaza (BME) Siti Nor Wahida Fauzi (BME) Ahmad Shahir Ismail (EECE) Hafizul Anwar Raduan (Comp. E) Advisor: Dr. W Mark Richter (Ph. D, Director of Research and Development, MAXmobility)
MAXmobility n n 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 n Located on tubular hoop that can be mounted on different sizes of wheelchair’s wheel. n To access the load applied by manual wheelchair user. n Consist of DAQ, load cell, wireless transmitter, battery, DC/DC converter, sensor.
Propulsiometer Battery Viasat Mini. DAT™ Sensor Load Cell DC/DC Converter
Propulsiometer
Data Collected Angle vs. time n Torque vs. time n ¨ Tx ¨ Ty ¨ Tz n Force vs. time: ¨ Fx ¨ Fy ¨ Fz
Force, Torque, Moments & Wheel Angle Data collected from propulsiometer to the PC
Load Cell Signals n n 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. 4412 m. V.
Problem Mini. DAT is no longer available n Bulky n Use too much power n Cost = $4, 625. 00 n
Specific Goals Size: 2 x 0. 5 inches (LWH) n Weight: ~0. 25 lb n Cost: less than $1000. 00 n
Target Specification n n n n 6 analog channels A/D converter with 12 -bit resolution 1 quadrature encoder input Wireless capability Sampling rate of at least 10 k. Hz 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 n Pros: n ¨ Meet all requirements ¨ Built-in Linux/Windows OS n Cons: ¨ Does not support Lab. VIEW ¨ Expensive ~$1500
Model 526 n n n Four 24 -bit quadrature encoder inputs Eight 16 -bit analog ± 10 V differential inputs 10 k. Hz sampling rate Approximately 4 x 4 inches Single supply (5 V, 5 m. A) input power
2 nd Approach Sheldon SI-MOD 68 xx n Pros: n ¨ Meet all requirements ¨ Built-in Linux/Windows and support the Lab. VIEW n Cons: ¨ Too expensive ~$2500
SI-MOD 68 xx n n n Up to 64 SE/32 DE Analog Inputs 16 -bit resolution, ± 10 V 100 khz/250 khz sampling Two 32 -bit quadrature inputs 7 watts in maximum configuration Approximately 4 x 4 inches
3 rd Approach n n 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 n Decision base on: n ¨ Low cost ¨ Flexibility in combining the components ¨ No unnecessary functions
Current status Design the circuit n Finalize & buy the components for the circuit n
Components (A/D converter) n MAX 186 ¨ 8 channel single-ended ¨ 12 -bit resolution ¨ Input range: 5 V ¨ Sampling rate of 133 k. Hz ¨ Operates at 5 V
Components (Quadrature decoder) n GEN-2122 -5 ¨ 22 -bit Up/Down counter ¨ 5 V or 3. 3 V I/O capability ¨ Max input speed of 10 MHz ¨ Operates at 5 V
Components (2. 4 GHz wireless transceiver) n Nordic Semiconductor n. RF 2401 ¨ Data rate up to 1 MHz ¨ Operating voltage: 3 V ¨ Built-in antenna ¨ Size: 1. 44 x 0. 79 x 0. 9 inches (LWH)
Components (5 V Voltage Regulator) n National Semiconductor LM 2937 ¨ Max input voltage: 26 V ¨ Output voltage: 5 V ¨ Current output: 10 m. A (max)
Circuit example
Work Contribution
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