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

2. 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.

3. 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.

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

5. 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.

6. 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.

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

8. Stress Analysis

9. 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

10. Load Cell Calibration (continued)

11. 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

12. 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

13. 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

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

15. Arduino Code

16. 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

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

18. 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

19. Gantt Chart

20. Questions ???