Transcript An ankle strengthening device with virtual reality interface for children with cerebral palsy Outline Overview  Details of Chosen Design  Materials and Manufacturing  Conclusion  Overview.

An ankle strengthening device with virtual
reality interface for children with cerebral palsy
Outline
Overview
 Details of Chosen Design
 Materials and Manufacturing
 Conclusion

Overview ○ Details of Chosen Design ○ Materials & Manufacturing ○ Conclusion
The Need

A strength training
device that
 is safe for in-home
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use
requires minimal
setup or user
training
is affordable
is portable
motivates patient
participation
Overview ○ Details of Chosen Design ○ Materials & Manufacturing ○ Conclusion
The Scope
To design an at-home ankle strengthening
device – Flex2Play – that motivates
participation by interfacing therapy with
a WiiMote which controls online video
games
Overview ○ Details of Chosen Design ○ Materials & Manufacturing ○ Conclusion
Design Specifications

Full range of motion
 30° from neutral in DF
 -50° from neutral in PF

Progressive Resistance
 35 Nm DF torque
 101 Nm PF torque
 Resistance in at least
20° Dorsiflexion
15% increments
Affordable – $200 target
Portable – 30lbs
8 ft3
 Virtual Reality Interface
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 2010 BME401 Group
“Wii Controlled Gaming
for Therapy”
0° Neutral
Dorsiflexion
τ=F*d*sin(θ)
F=35Nm/(0.28m*sin(90))
F=125N
Plantarflexion
τ=F*d*sin(θ)
–50° Plantarflexion
F=101Nm/(0.28m*sin(90))
F=361N
Overview ○ Details of Chosen Design ○ Materials & Manufacturing ○ Conclusion
Chosen Design: Elastic Bands
Four Main
Components:
 Footplate
 Base
 Hinge Joint
 Elastic Bands
Overview ○ Details of Chosen Design ○ Materials & Manufacturing ○ Conclusion
Footplate
Exploded Isometric View
Overview ○ Details of Chosen Design ○ Materials & Manufacturing ○ Conclusion
WiiMote Controller Connection
Side View
Isometric View
Overview ○ Details of Chosen Design ○ Materials & Manufacturing ○ Conclusion
Base
Isometric View
Overview ○ Details of Chosen Design ○ Materials & Manufacturing ○ Conclusion
Overview ○ Details of Chosen Design ○ Materials & Manufacturing ○ Conclusion
Hinge Joint
Exploded Front View
Isometric View
Overview ○ Details of Chosen Design ○ Materials & Manufacturing ○ Conclusion
Elastic Band Connections
Overview ○ Details of Chosen Design ○ Materials & Manufacturing ○ Conclusion
Elastic Band Connection
Calculations
Overview ○ Details of Chosen Design ○ Materials & Manufacturing ○ Conclusion
Manufacturing
Estimated Flex2Play market size
 114,000 children in US age 5-18 with spastic
cerebral palsy
Commercial Production
 Expected 1,000 units sold in the first year
 Expected 4,000 units sold in next 5 years
Near Future
 One Flex2Play prototype for device evaluation
 10 devices for evaluation in small sample
Overview ○ Details of Chosen Design ○ Materials & Manufacturing ○ Conclusion
Materials
Component
Footplate
Products
footplate (1), side plates (2), washers (4),
screws (4), nuts (4), straps (2)
Base
telescoping post (1), base post (1), pin (1),
base plate (1), stabilizing posts (2), rubber,
connection hoop, adhesive
$165.70
Hinge
hinge plate (1), bushing (4), axle (1), bolt
(2), set screw (2), washer (2), Velcro
$83.90
1 device
Materials Costs $314.66
Manufacturing $225.00
Costs
Total
$539.66
10
devices
$156.58
$225.00
Mass
production
$39.00
$150.00
$381.58
$189.00
Cost for 1 device
$65.09
Overview ○ Details of Chosen Design ○ Materials & Manufacturing ○ Conclusion
Conclusions

Specification Fulfillment
 Affordable – $189 mass production
 Portable – 8.82 lbs and 2 ft3
Safety Considerations
 Future directions

 Intellectual Property
 Pilot Study with 10 devices

Reflections
 What we learned
 What we would do differently
Works Cited
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Aisen, ML, et al. "Cerebral Palsy: Clinical Care and Neurological
Rehabilitation." Lancet Neurology 10.9 (2011): 844-52.
Boley, B. L. (1997). Overview of Motor Types Tutorial. Retrieved
October 23, 2011, from http://www.oddparts.com/acsi/motortut.htm
Compression Springs. 23 October 2011.
<http://www.leespring.com/int_learn_compression.asp>.
Dynetic Systems. (n.d.). Brushless vs Brushed. Retrieved October 23,
2011, from Dynetic Systems:
http://www.dynetic.com/brushless%20vs%20brushed.htm
Pinneger, Gavin J and Andrew G. Cresswell. "Residual force
enhancement after lengthening is present during submaximal plantar
flexion and dorsiflexion actions in humans." Journal of Applied
Physiology (2006): 18-25.
Simple Machine Elements. 23 October 2011.
<http://cnx.org/content/m13594/latest/>.
The Hygenic Corporation. (2006). Resistance Band & Tubing
Instruction Manual. Akron, OH, USA.
Torsion Springs. 23 October 2011.
<http://www.leespring.com/int_learn_torsion.asp>.
An ankle strengthening device with virtual
reality interface for children with cerebral palsy
Overview ○ Details of Chosen Design ○ Materials & Manufacturing ○ Safety○ Conclusion
Elastic Bands