Advance Rehabilitation Technology

William DurfeeDepartment of Mechanical Engineering

University of MinnesotaMinneapolis, USA

Including a few case studies

• Stimulated Muscles = Power • Brace = Trajectory guidance • Brake = Control, stability

HUMAN/MACHINE DESIGN LABDepartment of Mechanical Engineering

University of Minnesota(www.me.umn.edu/labs/hmd/)

Fu

x,vT

X

�

�

PE Force-Velocity

CE Force-Velocity

Fscale

IRC

CE Force-Length

Activation Dynamics (2nd order)

PE Force-Length

u

V

X

V

X

Force

Passive Element

Active Element

Muscle mechanics

Smart orthotics + electrical stimulation for gait restorationHaptic interfaces for virtual product

prototyping, smart knobs for cars

Rehabilitation engineering-Tele-rehabilitation-Stroke rehab-Driving simulators

Human assist machines-Compact power sources-Powered exoskeletons-Natural control

Medical device design-Evaluation of surgical tools

Rehabilitation Engineering

The application of engineering principles to treatment, services and devices related to people with disabilities

Disability

“A physical or mental impairment that substantially limits one or more major life activities.”

Americans with Disabilities Act, 1990

20-49 million in U.S.

6.5% of GDP

12.6% of population

MEDICAL MODEL

StrokeSCIMS

Muscular Dystrophy

ArthritisAmputationAlzheimer’s

Medical Condition Cognitive•Sensory/Motor integration•Memory•Reasoning

Physical

Motor

Sensory

•Speech•Balance•Gait•Coordination•Grip•Arm

•Sight•Sound

Impairment

SOCIALMODEL

PERSON

ABILITYENVIRONMENT

Therapeutic Technology

Any equipment that treats an impairment

www.empi.com

www.donjoy.com

Assistive Technology

Any equipment that increases ability or function

USER TASK

AT DEVICE

1

2

Person

Motor

Sensory

Cmd & Control

Hearing Sight

MobilityGrip

Arm•Wheelchair•Surgery•FES•Prosthesis•Orthosis

•Hearing aid•Cochlear implant•Signing

•Reading machine•Refreshable Braille•Glasses•Mobility

•ECU•Computer•Communic.•Robot•Speech•Driving

bionics.ossur.de

www.abledata.com

www.abledata.com

www.dekaresearch.com

www.ric.org

www.technologyreview.com

Photos from Paraplegia News and Sports ‘n Spokes

IT'S MORE THAN THE TECHNOLOGY

30-50% of AT devices are abandoned

HOT TECHNOLOGIES• Stroke rehabilitation

– Rehab robots– Constraint Induced Movement Therapy– Game therapies

• Prosthetics– War injuries– Diabetics

• Activity monitoring– Alzheimer's

• Brain-computer interfaces• Wheelchair technology• Retinal implants• Cochlear implants

Stroke

• 5.8 million (2.6% of population)• 780,000 new per year• Third leading cause of death

–150,000 per year

• #1 cause of adult disability

American Stroke Association

Rehab Treatment Robots

MIT Manus

Prosthetics

• DARPA Revolutionizing Prosthetics– 2005 –2009 (?)– $30.4 million– Johns Hopkins APL prime

contractor– Arm design, control, HMI

www.darpa.mil

Deka Arm

Manchester Union Leader IEEE Spectrum

Brain-computer interface

Braingate cortical implant system

EEG based, Bin He, UMN

iBOT Mobility, Independence Technology (Johnson & Johnson)

ibotnow.com

Retinal Implant

Argus II Retinal Implant System, University of Southern California artificialretina.energy.gov

TELEREHABILITATION

"Telerehabilitation is the clinical application of consultative, preventative, diagnostic, and therapeutic services via two-way interactive telecommunication technology."

American Association of Occupational Therapists Position Paper on Telerehabilitation

7 hrs

Why tele?

• Clients in rural locations• Clients in urban locations, but have

transportation challenges–No car–Poor public transportation

• Eliminates transportation time

HOME-BASED STROKE

REHABILITATION

Collaborators: James Carey, Samantha Weinstein, Ela Bhatt, Ashima NagpalFunding: NIDRR, H133G020145

Post-Stroke Rehab

• Constraint-Induced Movement Therapy

• Robot Therapy

• Virtual Reality

• Wii

• Motion Biofeedback Therapy

Goal: Create new brain pathways to compensate for injured tissue

Use the afflicted limb while concentratingW. J. Chu et. al, Stroke, 2002; D. M. Feeney and J. C. Baron, Stroke, 1986; R. A. Schmidt and T. D. Lee, Motor control and learning: A behavioral emphasis, 1999; C. J. Winstein, P. S. Pohl, and R. Lewthwaite, Res Q Ex Sport, 1994; J. R. Carey, E. Bhatt, and A. Nagpal, " Exercise and Sport Science Review, vol. 33, pp. 24-31, 2005.

NJIT-RAVR

CIMT

Mary Free Bed Rehab Hospital

MIT-MANUS

Problem To Be Solved

Can a tracking-training system developed for the clinic1 be deployed in the home?

1Carey et al, Brain, 2002

Home-Based, Clinician-Directed Therapy

• At home• Patient in control• No transportation needed

Limitations• No therapeutic touch• Cannot recognize clinical

subtleties• Cognitive, physical abilities

of patients

Tracking Task

Joint motion controls vertical motion

Many trials

Vary the Waveform

Frequency (Hz) 0.2, 0.4, 0.8

Amplitude (% ROM) 0-50, 30-70, 50-100, 0-125

Duration (s) 5,10,15,20

Vary the Posture

And the direction…

FeedbackTracking

Provide Directions and Feedback

Study #1: Finger & WristCarey et al, Neurorehabil Neural Repair, 2007; Durfee et al, J Medical Devices, 2010

Study Details

• 24 subjects with chronic stroke• 2 to 305 mi. from UMN, one at 1,057 mi.• 180 trials/day x 10 days = 1800 trials

Pre & Post Assessment1. Box and Block2. Jebsen Taylor Hand Function3. Finger range of motion4. Finger tracking accuracy5. fMRI (cortical activation intensity and

location)

Tracking and Move GroupsCarey et al, Neurorehabil Neural Repair, 2007

Lesion

NeurorahabNeural Repair, 21:216, 2007

PRE

POST

Key Results• Improved on functional tests• Improved in tracking accuracy and finger

ROM (track group)• Cortical activity shift towards lesioned side• Tracking and move group had similar

results• High tolerance for technology, could self-

install system and don/doff sensors

Conclusion: Tracking training at home is feasible and effective.

Study #2: Ankle

Technology Architecture

BUTTON

ROTARY POT LPF, 10 HZ ADC, 16-BITMICROCONTROLLER

PC

USB CELLULAR MODEM

INTERNET VIA CELL PHONE NETWORK

USBWEBCAM W/ MIC

PC

INTERNET

USBWEBCAMW/MIC

CLINIC STATION

HOME STATION

USBWIRE

INTERFACE BOX

At the Patient’s Home

1-Button Operation

Tele Session, Example 1

Tele Session, Example 2

Careful Design is Critical• Easy to use

–1 button operation–Simple setup…by the patient–Therapist controls tele

• Donning/doffing sensor• Works anywhere

–Cellular modem for internet

• Anticipate events–Failure effects analysis

6060

Protocol (n=20)

PRE-TEST POST-TEST

TREATMENT(TRACKING)

CONTROL(MOVING)

Ankle tracking accuracyBrain reorganization (fMRI)Gait analysis (kinematics)Walking speed

Ankle tracking accuracyBrain reorganization (fMRI)Gait analysis (kinematics)Walking speed TRACK GROUP

20 days at home3600 tracking trials180 trials/dayTeleconsult 3X/wk

Gait Analysis

• Minimum toe clearance• Functional range of motion

Results, One Subject

Post-Test

25°

20°

15°

10°

5°

0°

-5°

-10°

-15°

-20°

Dorsi flexion

Plantar flexion

Sagi

ttal A

nkle

Ang

le (d

egre

es)

Pre-Test

Normal

Post-Test

25°

20°

15°

10°

5°

0°

-5°

-10°

-15°

-20°

Dorsi flexion

Plantar flexion

Sagi

ttal A

nkle

Ang

le (d

egre

es)

Pre-Test

Normal

Cortical Activation (1004)

Stroke on L side

Preliminary Assessment of Home-Based Stroke Rehab

• Favorable subject reaction• Measurable rehab outcomes• Requires tech support• Technology changing quickly• Optimal rehab paradigms not known• Cost ???

Remember to focus on patient needs

Practical Applications of Muscle Stimulation

MUSCLE!

MUSCLE

• 40% of body weight• 640 move you• Work in pairs, can only push• Eye muscles move 100,000

times/day• Gluteus maximus is largest• Sartorius is longest

REANIMATING PARALYZED

MUSCLE

Brain

Spinal Cord

Limb

Stimulator

Liberson foot-drop system, 1961

Heel switch triggered peroneal n. stimulationCorrection of foot-drop following strokeStarted field of FESSeveral commercial and research embodiments

Medtronic implanted foot-drop system

Upper Limb FES

• Grasp restoration• Forearm and hand muscle stimulation• Rudimentary grip facilitates independence

NeuroControl FreeHand

Cleveland FES Center

Cleveland FES Center

FEXTERNAL

CONTROL STIMULATORInputs

Measurements

• Improve health through weight bearing• Brief standing: social and functional• Limited ambulation in vicinity of wheelchair• No balance, no change in neuro function

LOWER LIMB FES: Standing and Gait

asimo.honda.com

IS IT LIKE A BIPED ROBOT?

WHAT MAKES FES DIFFERENT?

• Not enough muscles • Not enough sensors• Muscle force too low• Muscle fatigues• Spasticity• Difficult to control with

precision• No control over rest of body• Command channel• Muscles are not electric

motors• Size/weight constraints • Reliability

Muscle stimulation

provides power

Brakes for locking and

control

Orthosis provides guidance

and support

CBO in operation

• Stimulate quadriceps for stance control– High force, high

energy (relatively)• Stimulate reflex for

stepping motion– Erratic– Habituates

• CBO controls swing, locks during stance

• Orthosis a mounting platform for sensors

Cleveland FES Center

ENERGY STORING BRACE

Energy Storing Orthosis

(a) (b)

Take in ambient (atmospheric) air as knee flexes

Release ambient (atmospheric pressure) air as hip flexes

Compress air and force into accumulator as knee extends

(c)

Discharge pressurized air to drive hip extension

Energy budget• ~30 nM over 60 deg

of motion• 31.4 J per extension• Extract 14 J per

cycle

Hausdorff and Durfee, Med Biol Eng Comp, 1991. 29:269-280.

How Much Energy Can Be Extracted From the Quads?

Celotta, MS Thesis, 2006

N = 10 non-impaired subjects70 deg liftStim fixed for 50 Nm at 90 degEnergy = gravity lift + brake

PASSIVE LIFTCONTROLLED TRAJECTORY

STIM for 2.0 s1. rest for 3.0 s, 40% duty cycle2. rest for 8.0 s, 20% duty cycle

Normal gait, quads on 35%

15-18 J Minimum Over All Subjects

Limitations: (1) Non-impaired subjects, (2) 50 Nm target torque

ADAMS dynamic model

J. Biomechanical Engineering, 127(6):1014-1019, 2005.

Bench prototype

Leg: accurate length, inertia, COM

Gas springs: Arvin Motion Control

Cylinders: 7/8”bore, 2.5” stroke,

BimbaValve: solenoid, 2-

position, Mead

Accumulator: teflon tube, 1/16”

bore x 18”

ISSUES IN POWERED

EXOSKELETONS

General Electric Hardiman

Sarcos Raytheon XOS Exoskeleton popsci.com

LIFESUIT, theyshallwalk.org

Cyberdyne, HAL-5

ReWalk, Argo Medical Technologies

www.argomedtec.com

Ironman, 2008

Challenges• Power

supply• Actuators• Packaging• Control

The Power Supply

Power Supply

ENERGYSOURCE

ENERGYCONVERSION

USEFULPOWER

Battery Conditioning

Hydrogen Fuel Cell

Hydrocarbon Fuel IC Engine

www.hardingenergy.com

Battery Metrics

DC Motor + Battery

• 285 lb total • 66 lb battery• 20 min life

Energy Density

0.2 0.6

20

0

5

10

15

20

25M

J/K

g

NiMh Lith Ion Methanol

Power Density

160250

1453

0

500

1000

1500W

/Kg

NiMh Batteries

electrochemicalreaction

Electrical PowerDC servo Mechanical Power Output

~ 145-260 kJ/kg (servo motor)(290 kJ/kg) %100≈η %90%50 −≈η

Batteries / DC Motors

83HC(46,350 kJ/kg)

internalcombustion PE

(hot)

adiabaticexpansion

KE

adiabaticcompression PE

(cold)

adiabaticexpansion Mech. Power Output

(pneumatic actuator)~1,500 kJ/kg (desired)

(goal) %24.3≈η

IC Engine Compressor

Energy Transduction

Source: Prof. Eric Barth, Vanderbilt University

POWERED ANKLE ORTHOSIS

Georgia Institute of TechnologyMilwaukee School of Engineering

North Carolina A&T State UniversityPurdue University

University of Illinois, Urbana-ChampaignUniversity of Minnesota

Vanderbilt University

www.ccefp.org

A National Science Foundation Engineering Research Center

Vision: Transform fluid power by making it more compact, more efficient and more effective

Goals:1) Dramatically improve the efficiency of existing FP systems2) FP enabled passenger cars with better fuel economy and cost

structure 3) New to the world human scaled FP devices that can do useful work4) Make all of the above ubiquitous

Test Beds

Excavator Hydraulic Hybrid Vehicle

Rescue Robot Wearable Fluid Power

Portable Fluid Power Exists

The Baggage

19" x 18" x 20", 87 lbs

Why the Ankle?

• Cyclic motion• Known dynamic profiles• Reasonable angle, torque power range• Stringent packaging constraints

Ankle Dynamics

-10

-5

0

5

10

15

20

0 50 100

Gait Cycle (%)

Ang

le (d

eg)

-100

1020304050607080

0 20 40 60 80 100

Gait Cycle (%)

Torq

ue (N

-m)

85 Kg person walking, source: Winters: Biomechanics of Human motion

Ankle Power, 85 Kg Person Walking

-50

0

50

100

150

200

0 20 40 60 80 100

Gait Cycle (%)

Pow

er (W

)

Peak ~200 W

Average ~13 W

85 Kg person walking, source: Winters: Biomechanics of Human motion

With David Kittelson, Lei Tian, Department of Mechanical Engineering, University of Minnesota; and Eric Barth, Department of Mechanical Engineering, Vanderbilt University

Miniature HCCI Free-Piston Engine-Compressor

• Develop engine-compressor to provide about 10 W of compressed air

• Applications: ankle orthosis, human assist tools• Advantage over competition (projected)

– More compact than battery + motor– Easier to manufacture than micro turbine

Homogeneous Charge Compression Ignition

Image from New Scientist, Jan, 2006

Engine CAD Model

Next Steps

• Determine fuel• Dynamic model

–Optimize combustion, bounce, compression chambers

–Optimize stroke/bore

• Thermodynamic model–Predict efficiencies

• Construct & bench test prototype

FUTURE MICRO FPAC + 1 KPSI ACCUMULATOR

CONCLUDING REMARKS

And a few other projects

Replacing muscle

Power (W/lb)

0

50

100

150

200

250

Muscle--peak Muscle--sustained

Electric motor Automobileengine

Vogel (2001), "Prime Mover"(Aircraft engine, piston: 700; Aircraft engine, turbine: 2500)

Muscle metrics• Uni-direction, short stroke (5-20%)• Pull force: 30 lbs/sq. in.• 90 W/lb peak

– 180 lb athlete w/ 72 lb of muscle does 370 W sustained = 5 W/lb

• 25% efficient• Compliant, back-drivable• Extensive infrastructure• Fatigues• Clean• Cool• Quiet

Vogel (2001), "Prime Mover"

!

Competition is $19 Piece of Plastic

Thanks!