Development of a Smart Walking Cane with Biofeedback I S A B E L L E - - PowerPoint PPT Presentation

I S A B E L L E D . P U M F O R D 1 , 2, M A R C U S J . B A I L E Y 1 , 4A N D P A T R I C K M . A U B I N 1 , 3,

1R R & D C E N T E R O F E X C E L L E N C E , V A P U G E T S O U N D , S E A T T L E , W A , 2C O L L E G E O F E N G I N E E R I N G A T U N I V E R S I T Y O F A R K A N S A S ,

F A Y E T T E V I L L E , A R

3D E P A R T M E N T O F M E C H A N I C A L E N G I N E E R I N G A N D

S C H O O L O F M E D I C I N E 4 , U N I V E R S I T Y O F W A S H I N G T O N , S E A T T L E , W A E M A I L : I D P U M F O R @ U A R K . E D U

Development of a Smart Walking Cane with Biofeedback

Introduction

 27 million adults suffer from Osteoarthritis in the

United States

 Reducing knee adduction moment, KAM, has been

show to decrease pain and improve function

 Wanted to create a walking aid that encourages

increased cane loading and KAM reduction using a vibrotactile biofeedback loop

Device Requirements

 Provide cane load biofeedback  Mobile battery operated  Able to store data  Person up to 113 kg (250 lbs)  Able to measure force from 0N to 222N  Able to record date and time  Similar weight to conventional cane.  Able to mechanically withstand up to 222N

Initial Design

 Force Link outputs charged based on piezoelectric

• effect. Displacement results in a charge being

created.

 When compressed an Inline Amplifier creates a

charge from 0-5V; can detect up to 265N. Force Link Handle holding electronics bent during testing

Current Design

6mm motor PBC protects components and allows for sturdy exterior On and off switch Smart Cane provides biofeedback in the form of a vibration when 20% of user’s body weight is loaded

Electronics

Real Time Clock (RTC) Open logger for SD card Motor Controller Promicro Controller

• Promicro controls computerized system
• Open logger allows data to be stored on SD card
• Real Time Clock records actual time and date for record keeping
• Motor controller controls vibrating motor

Electronic Communication

ProMicro RTC

Inter-Integrated Circuit (I2C)

Inline Amp Motor Controller SD Logger

10bit Resolution Analog Pin TX RX Pulse Width Modulation (PWM) Serial Link

Force Measurement Validation

• 180
• 160
• 140
• 120
• 100
• 80
• 60
• 40
• 20

100 200 300 400 500 600

Force (N)

Sample Number (time)

Force Measured by Cane and Force Plate

Cane Force Plate

RMS Error ±2.5 N

Arduino Software

 Records force  Records peaks  Turns motor on and off  Loop repeats every 20 milliseconds, 50 hertz

Max threshold Min threshold Time Force (N) Peak

Conclusion

Provide cane load biofeedback Vibrotactile feedback loop Mobile battery operated Untethered and uses Li-ion batteries Able to store data Data logger uses SD card Person up to 113 kg (250 lbs) Yes Able to measure force from 0N to 222N Up to 265N Able to record date and time Uses RTC for real time and date Similar weight to conventional cane. About 2 kg of weight added Able to mechanically withstand up to 222N New PBC model is able Requirement Smart Cane

Acknowledgements and Questions

 Study funded by the Department of Veterans Affairs

grant A9243C; RR&D Center of Excellence for Limb Loss Prevention and Prosthetic Engineering., VA Puget Sound, Seattle WA.