FLEX2PLAYAn ankle strengthening device with virtual

reality interface for children with cerebral palsy

October 26, 2011BME 401 Senior Design

Mentor: Jack Engsberg, PhDAmanda Meppelink(Presenter), Kelly Hill, Liz Phillips

The Need A strength training

device thatis safe for in-home

userequires minimal

setup or user training

is affordableis portablemotivates patient

participation

Overview ○ Alternatives○ Analysis of Designs ○ Chosen Design ○ Our Approach

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 ○ Alternatives○ Analysis of Designs ○ Chosen Design ○ Our Approach

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 Available in at least 15%

increments Affordable – $200 target Portable – 8 ft3

Virtual Reality Interface 2010 BME401 Group “Wii

Controlled Gaming for Therapy”

Overview ○ Alternatives○ Analysis of Designs ○ Chosen Design ○ Our Approach

20° Dorsiflexion

0° Neutral

–50° Plantarflexion

Plantarflexionτ=F*d*sin(θ)F=101Nm/(0.28m*sin(90))F=361N

Dorsiflexionτ=F*d*sin(θ)F=35Nm/(0.28m*sin(90))F=125N

Alternatives

Mechanism of Resistance

Springs Gravitational Magnetism Motors Elastic

Overview ○ Alternatives○ Analysis of Designs ○ Chosen Design ○ Our Approach

SpringsOverview ○ Alternatives○ Analysis of Designs ○ Chosen Design ○ Our Approach

Left: Torsion

Middle: Compression

Right: Extension

PulleysOverview ○ Alternatives○ Analysis of Designs ○ Chosen Design ○ Our Approach

Use free weights to provide resistanceIn plantarflexion,

pulley used to alter direction of force

Levers Consist of fulcrum,

load, and effortMagnitude of effort

based on distance from fulcrum

Overview ○ Alternatives○ Analysis of Designs ○ Chosen Design ○ Our Approach

Magnetism Use permanent

magnet, electromagnet, or combination of both

Overview ○ Alternatives○ Analysis of Designs ○ Chosen Design ○ Our Approach

Motors AC Motor

Ideal for fixed speed applications

DC Brushed Motor DC Brushless Motor

Speed controlled by adjusting amount of electrical current

Overview ○ Alternatives○ Analysis of Designs ○ Chosen Design ○ Our Approach

Side View

Front View

Elastic Bands Elastic bands

provide resistive forcetan = extra thinyellow = thinred = mediumblue = extra heavyblack = special heavysilver = super heavygold = max

Overview ○ Alternatives○ Analysis of Designs ○ Chosen Design ○ Our Approach

Criterion for Pugh Chart

EssentialCost, Safety, Strength Range, Range of

Motion, Ability to Interface with Wii High Importance

Durability, Train Both PF and DF Important

Size, Weight, Ease of Setup, Ease of Use Other

Strength Resolution, Train with Knee Extended, Train More than One DOF

Overview ○ Alternatives○ Analysis of Designs ○ Chosen Design ○ Our Approach

Pugh ChartOverview ○ Alternatives○ Analysis of Designs ○ Chosen Design ○ Our Approach

Springs Pugh Results High score

Cost ($1-$24)SafetyStrength Range

Low scoreStrength ResolutionMore than One

Degree of Freedom

Overview ○ Alternatives○ Analysis of Designs ○ Chosen Design ○ Our Approach

Motor Pugh Results High Score

Strength RangeRange of MotionTrain Both PF and DF

Low ScoreVery Expensive

($122-$966)SafetyDurability

Overview ○ Alternatives○ Analysis of Designs ○ Chosen Design ○ Our Approach

Chosen Design: Elastic Bands

Overview ○ Alternatives○ Analysis of Designs ○ Chosen Design ○ Our Approach

Left: Iso ViewTop Right: Top ViewBottom Right: Back View

Flex2PlayOverview ○ Alternatives○ Analysis of Designs ○ Chosen Design ○ Our Approach

LimitationsDoes not reach maximum PF force valueVariability among patients

Design ScheduleOverview ○ Alternatives○ Analysis of Designs ○ Chosen Design ○ Our Approach

Team ResponsibilitiesOverview ○ Alternatives○ Analysis of Designs ○ Chosen Design ○ Our Approach

 

 

 

Liz – Expressive•Final Presentation•Web Designer•Research on Alternative Ideas

 

Kelly – Analytical•Preliminary Presentation•Weekly Reports•Research on Alternative Ideas•DesignSafe

 •Meet weekly with mentor•Write and revise reports•Conduct background research•Provide feedback to group

Amanda – Driver•Progress Presentation•Schedule Manager•Research on Chosen Design

Works Cited 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>.

FLEX2PLAYAn ankle strengthening device with virtual

reality interface for children with cerebral palsy

October 26, 2011BME 401 Senior Design

Mentor: Jack Engsberg, PhDAmanda Meppelink(Presenter), Kelly Hill, Liz Phillips