Instrumented Walker Skyler Bullington Tommy Frankenberger Larson Stacy Jairus Potts Rockwell Shields Chris Barnett

Purpose applied weight regardless of hand placement. The purpose of this project is to develop, build, and test an instrumented walker that is capable of reporting applied weight regardless of hand placement.

Background The Mayo clinic had a need for an instrumented walker Improve rehabilitation methods for patients Monitor reliance and walker use from patients Primarily used with Exoskeletons Research was conducted on how previous data was analyzed, procedures, and hardware used.

Design Criteria Improve existing designs Lightweight Removable Able to communicate with Labview Accurately determine the forces being placed on the walker Uniform wiring

Load Cell Selection Single axis load cell Determine forces being applied by the patient in the z-direction Load Cell selected that could measure weight up to 200 pounds with plus or minus 1lb accuracy.

Design Two custom attachments made of aluminum were designed that would allow the load cell to be mounted and screwed onto the bottom of each leg of the walker. Design is removable and capable of transferring forces without failure.

Design Continued A box made of plastic to house the circuit board and battery. Mounted on the front crossbeam of the walker.

Stress Analysis

Load Cell Calibration Weight applied in 5 lb increments ranging from 0 to 60 Voltage read out from calibration board Entered into Excel Plotted and Curve Fitted Resulting functions for load

Load Cell Calibration (continued)

Electronics Criteria For Design Read 4 Load Cell Outputs on 4 Separate Channels High Level of Accuracy Low Voltage Battery Conservation Functionality Small and Lightweight

Electronics Selection Microcontroller - Arduino Mega 2560 Chosen for more Digital Inputs/Outputs Processing latency is less than Uno R3 Battery - Rechargeable 1.2V 3000 mAh HR6 Inexpensive Batteries NiMH Safe for Hospital Use Alkaline AA substitute

Electronics Selection Analog To Digital Conversion - ADS 1234 Designed For Bridge Sensors 4 Channel Input Ultra Low Noise with Surface Mount Devices 24 Bit Resolution - 18 Effective Number Of Bits (ENOB) Wireless Module - XBee 1mW Series 1 Low Power Consumption 3.3V , 50mA Max 300 Feet Range

Printed Circuit Board Design Add On Card for Arduino Mega ADC Requires SMD Components Manufacturer Recommended Parts Used Terminals For Load Cell Connections External 4.9152 MHz Crystal Oscillator Placement for Wireless Module

Arduino Code

Labview Programming Fig. Input Testing Setup -Data read in from USB using VISA Serial -Input string split into four separate values, converted to decimal -Input voltages converted to individual forces using calibration formulae -Information displayed and plotted in GUI Fig. Input Testing Setup

LabView & Arduino Integration Fig. Labview GUI Fig. Block Diagram

Results Full design prototype was built Arduino was able to communicate with LabView Fully functional LabView code with counterfeit signal Fully functional Arduino code Fully developed PCB board

Gantt Chart

Questions ???