Chiari, Lorenzo - Intelligent Assistive Technologies for...

Department of Electronics, Computer Science, and SystemsAlma Mater Studiorum – Università di Bologna

[email protected]

Intelligent Assistive Technologies for Balance and

Movement ControlLorenzo Chiari, PhD

Patras - July 3, 2008 4th Summer School on Emerging Technologies in Biomedicine

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The big challenge

“We are in the midst of a profound demographic shift, moving from a world in which the majority of the population is relatively young to one in which a significant proportion of people are over the age of 65. This change poses both a challenge and an opportunity for the design of intelligent technology.”

(Martha E. Pollack, Intelligent Technology for an Aging Population: The Use of AI to Assist Elders with Cognitive Impairment. In AI Magazine 26(2): Summer 2005)


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The big change


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• From a social social point of view, the main challenge of this demographic change will be to preserve for as long as possible the autonomy and independency of ageing people, allowing them to spend in the best way their old age, and relieving their relatives from their care.

• From an economiceconomic point of view, meeting the needs of elderly persons will put enormous pressure on the healthcare systems. Therefore, one of the main challenges will be to reduce the costs for medical assistance to elderly people.

Challenges


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Baby boomers at the gate…

“The role of technology in enhancing the lives of older but otherwise healthy Americans is not well understood or appreciated. I will review a variety of technologies that have been developed to support the independence and securityof an aging population in a variety of living environments. The categories of technology we consider are: * assistive devices that compensate for motor, sensory or cognitive difficulties; * monitor and response systems, both for emergency response to crisis situations and for early warning for less critical and emerging problems; * and social communication aids.”

Baby Boomers at the Gate - Enhancing Independence Through Innovation and Technology. Statement of Dr. Gregory Abowd. Hearing - The U.S. Senate Senate Special Committee on Aging (May 20, 2003)


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Assistive Technologies

• Assistive technology (AT) is a generic term thatincludes assistive, adaptive, and rehabilitative devicesand the process used in selecting, locating, and usingthem.

• AT promotes greater independence for people withdisabilities by enabling them to perform tasks that theywere formerly unable to accomplish, or had greatdifficulty accomplishing, by providing enhancements to, or changed methods of interacting with, the technologyneeded to accomplish such tasks.

(A.M. Cook and S. Hussey, Assistive Technologies: Principles and Practice (2nd Edition) Publisher: Mosby, 2001)


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• Assistive Technologies have the potential to enhance the autonomy and

quality of life of elderly people as well as to significantly reduce the cost associated

with elderly care (a study in Finland suggests a reduction in the order of 50%).

• Overall, AT can improve the quality of life of elderly people at home and reduce the

need of caretakers, personal nursing services, or the transfer to nursing

homes. Therefore, there is a twofold goal of AT: a social advantage (better quality better quality

of lifeof life) and an economic advantage (cost cost reduction for the welfare statereduction for the welfare state).

From challenges to opportunities


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Movement means life

Mobility problems…• have a very negative effect on an elderly person’s life

and health• are both a cause and a consequence of falls

• accidental falls represent the sixth cause of death among elderly

• it is estimated that one in three people aged 65+ is at risk of falling

• for people aged 80+ the figure increases to one in two people


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0

20

40

60

80

100Balance / gait

Cardiovascular

Environment

Medication

Feet / footwear

VisionMedical

Depression

Risk factor

% o

f pa

tient

sw

ithea

ch r

isk

fact

or

Other

Risk factors for falls


10


11

Adapted from Hausdorff et al, J.Appl.Physiol., 2001

Physiological and neuropsychological factorsassociated with gait instability and falls


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Home, tricky home

Ambient Assisted Living (AAL)


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Financial impactThe cost of each fall is 25.000 € and

10.000 € per year thereafter

Consequences Consequences of fallsof falls

Psychological problemsfear of falling causes people to restrict their activities50% of those who fall will suffer fear of further falls

Reduction of social participation

Physical impairment


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• It has been demonstrated that physical activity based interventions can improve motor and cognitive functioning in older people, both with and without age-related pathology.

• Evidence suggests more effect when interventions take place over longer time periods, when interventions are individually tailored, and when interventions also include exercises in the home environment.

… and the technology?

A strategy


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MEMS technology offers adequate body fixed sensors (BFS) that, clustered as a wireless network, and in combination with embedded microsystems and tele-communication protocols, can provide effective solutions for monitoring older people in their home environment and for conditioning their motor behavior, either directly or indirectly.

Enabling technologies


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Pervasive Healthcare

Camera

SpO2

EKG

EEG

BPGPS

Mp3PDA/phoneGateway

Motion Sensor

Use Pervasive Computing for day-to-day healthcare management to enable real-time, continuous patient monitoring & treatment

BodyAreaNetwork

FeaturesExtends remote monitoring model by enabling:

Physical presence of caregivers required only during emergenciesImproved coverage and ease of monitoring

Utilize in-vivo and in-vitro medical sensors

Mobile patients. No time & space restrictions for health monitoring

Better quality of care and reduced medical errors

Early detection of ailments and actuation through automated health data analysis

Nano-scale BloodGlucose level detectorDeveloped @ UIUC

Medical Tele-sensorCan measure and transmitBody temperature Developed @ Oak Ridge NationalLaboratory

Lifeshirt non-invasive monitoringDeveloped @ Vivometrics

Sports Health Management

Home-basedCare

Disaster Relief Management

Medical Facility Management

Applications

GOAL: Enable independent living, general wellness and disease management.

Credits: Luca B

enini(UN

IBO

)


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Differences & AdvantagesCurrent Healthcare

• Detect symptoms

• Go to medical facilities (professionals)

• Medical professional performs diagnosis and treatment.

Pervasive Healthcare

•Continuous Patient Monitoring.

• Automated diagnosis and treatment.

•Utilizing medical facilities only if required.

• Automated • Real-time • Inexpensive • Very efficient

Pervasive Healthcare Technology is Necessary to Meet Future Needs

• Manual• Slow • Costly• In-efficient

Credits: Luca B

enini(UN

IBO

)


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Pervasive Healthcare - Conceptual Overview

Medical Sensor Plane Management

PlaneKnowledge Generation

Plane

Patient

Doctor

• Collect Medical & contextual data• Local Processing• Medical Actuation • Storage Management

• Sensor Management• Generate Context

GenerateKnowledge

Data CollectionKnowledge

Feedback for Adaptation

Actuation

Credits: Luca B

enini(UN

IBO

)


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Body Area Networks: human in the loop

SensingTransductionA/D conversionLocal Processing

D

E

Wirelesscommunication

Input processingApplication-specificcomputationOutput rendering

Output actuation

• Continuous (streaming) communication• Real-time operation: Millisecond loop delay is required

for correct feedback operation, with human time constants

Short loop

Long loop


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Hardware platforms


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• Inertial sensors : based on inertial physical phenomenonAccelerometers : sense linear accelerationGyroscopes : sense angular velocity

• Other portable¹ sensorsPressure sensorsEarth’s magnetic field sensors (e.g.: magnetoresistivesensor)

¹ Portable: a necessary characteristic to define a sensor portable is its independence from external reference frame. (Earth magn. sensors are actually externally referenced, but we can consider the earth’s magnetic field everywhere constant)

Sensors ClassificationC

redits: Laura Rocchi (U

NIB

O)


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• Inertial sensors are designed to convert, or transduce, a physical phenomenon into a measurable signal. The physical phenomenon is an inertial force.

Inertial sensor design requires:

• a seismic mass (also called proof mass): to generate inertial force due to acceleration

• an elastic spring: to mechanically support the proof mass and restore neutral position

• a dashpot: to control the motion of the seismic mass and to obtain favorable frequency-response characteristic

+ a method to measure the displacement of the seismic mass, converting the mechanical displacement to an electrical output

Inertial sensorsC


NIB

O)


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nKsM

ω =2B

Ks Mζ =

⋅

0 0 0

0 0 0

( )s i

si

K x B x M a xKBx x x a

M M

⋅ + ⋅ = ⋅ −

+ ⋅ + ⋅ =

M

BKs

x0

Acceleration to be measured

iaG(s)ia x0

2

2

( )( )2( ) 1i

n n

X s GoG ss sA s ζω ω

= =+ +

Damping ratio Natural frequency

1/ nMGoKs

ω= =

Accelerometer: functioning principleC


NIB

O)


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• Two primary areas often motivate micromachined device applications: package volume or size and costs.

• Reducing the system cost is also a goal easily achieved by MEMS inertial sensors as compared to macroscopic systems, sharing process costs over a large volume, reducing the cost significantly.

• MEMS technologies are capable of reducing the sensor element and electronics board components to the scale of one integrated or two co-packaged chips

MEMS inertial sensorsC


NIB

O)


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Silicon Designs, Inc

adxl203

Some examples

adxl203

Credits: Laura R

occhi (UN

IBO

)


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Gyroscopes

Gyros for example, can be made by rotating mass within a gimbal, held by bearings attached to a case.

When the gyroscope is rotated around the axis (y) perpendicular to the spinning mass (x), an angular momentum is developed around the z-axis, and can be sensed by torque or force sensor

MEMS gyros do not have rotating parts, and bearings. They sense rotation from the Coriolis effect

Credits: Laura R

occhi (UN

IBO

)


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Sensing axis (rotation)Rotational velocity of the reference frame (driving axis)

⇒ The transducer structure is driven orthogonally (Coriolis effect)

0 0 0 2sCor z

KBx x x a yM M

+ ⋅ + ⋅ = = Ω ⋅

Ωz is the rate of rotation and y is linear velocity of the structure due to the drive

Gyroscopes: functioning principle

Ω

xy

z

aCor

vz :sensing axis

y: driving axis

The scalar governing equation of motion for a gyroscope device with a resonating mass in the y axis, rotated about the z axis is given by C


NIB

O)


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The function of a gyro is just like an accelerometer where the acceleration to sense is the Coriolis term 2Ωz dy/dt

The Coriolis acceleration is a modulated signal:Frequency from several kHz to tens of kHzAmplitude is in the sub-mg range.

From MEMS Handbook, Mohamed Gad-el-Hak

Credits: Laura R

occhi (UN

IBO

)

Gyroscopes: functioning principle


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IMU systems

Physilog

More sensors (eg, accelerometers+gyroscopes+magnetic sensors) to compensate for single sensor technological issues.

Some examples:

Credits: Laura R

occhi (UN

IBO

)


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mWatt Node (commercial)

Single board philosophyRobustness, Ease of use, Lower CostIntegrated Humidity & Temperature sensor

802.15.4 (Zigbee) CC2420 radio, 2.4 GHz, 250 kbps (12x mica2)3x RX power consumption of CC1000, 1/3 turn on timeSame TX power as CC1000

Motorola HCS08 processorLow power consumption, 1.8V operation,faster wakeup time40 MHz CPU clock, 4K RAM

PackageIntegrated onboard antenna +3dBi gainRemoved 51-pin connectorEverything USB & Ethernet based2/3 A or 2 AA batteriesWeatherproof packaging

Codesigned by UC Berkeley and Intel Research

moteiv.com

Credits: Luca B

enini(UN

IBO

)


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Advanced prototypes

ProtocolμC

2.4 GHz Radio

ApplicationProcessor

(EEC)

Solar Cell

Antenna

(a) IMEC 1.4cm3, SiP Mote for EEC, ECG , 500μW@1%, 400b/sec

3D stack

(b) UCB PicoBeacon Tx [21.4]1.9GHz, 400μW, 5kb/s

2.4*3.9cm2Battery/

powermgmt

1 2 4 GHz

500MHz-70

-50

-30 dB

(c) IMEC 0.18μ 0.25 mm2 UWB Tx0.5nJ/bit @ 10 kb/s

BatteryPowerMgmt

Credits: Luca B

enini(UN

IBO

)

Communication protocols


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Wireless networking standards

Data Rate (Mbps)

Ran

ge

ZigBee802.15.4 802.15.3

802.15.3a802.15.3c

WPAN

WLAN

WMAN

WWAN

WiFi802.11

0.01 0.1 1 10 100 1000

Bluetooth802.15.1

IEEE 802.22

WiMaxIEEE 802.16

IEEE 802.20

ULP BT (Wibree)802.15.1


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Off-the-shelf…

Nintendo Wii - Balance


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Health oriented services in ambient assisted living:

new opportunities for olderEuropeans

June 5, 2008 – Pacinotti Room, Palazzo dei Congressi, Pisa

Chair: Lorenzo Chiari, DEIS – University of Bologna


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SMILING

AIM: To develop and construct an advanced prototype of a wearable, non-invasive, micro-system for mechanical chaotic perturbations of gait pattern in order to counteract and prevent tendencies to fall.


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Scenario II:Tele-Monitoring

SENSACTION-AAL

AIM: to release and validate a system that provides means to perform customized, repetitive rehabilitation exercises directly at home via closed-loop biofeedback therapy; able to perform a monitoring of activities of daily living and subsequently quantify the actual level of physical activity by means of an ecological sensing approach;that can remotely transmit alarm and raw data in case unrecovered falls are automatically detected or activate proper corrective actions on the user. This will enhance daily home safety and security of elderly people living on their own.

Scenario I:Tele-Rehab

Scenario III:Tele-Care


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The Users’ PerspectiveThe Users’ Perspective

General perception of technology

Emotional-affective dimension

Cognitive-rational

dimension

from Mollenkopf, 2004

e.g. technologyis a threat

e.g. technologicalprogress is needed

Uptake of technology

Gender, age, education, former experiences with technology,

profession,socio-economic factors,living alone, interests,

life styles, comfort, appeal

Perception and use of everyday technology by the

elderly


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The use of disease or age specific assistive technology

perceived as a stigma

Socioeconomicse.g. cost, knowledge

Acceptance of assistive

technology

Disease specific factorse.g. cognitive impairment

Expected benefite.g. pro-activity,

attachment

Social functionalitye.g. meeting others

Cultural factorse.g.ethnicity

“Locus of control”

Difficulties

General perceptionof technology

from Mollenkopf 1994 & 2003

Uptake of assistive technologyby the elderly

The Users’ PerspectiveThe Users’ Perspective


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Major AchievementsMajor Achievements


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Listening for Balance: the Effect of Audio-Bio Feedback on

Postural Motor Learning


47Philippe Petit’s tightrope walk between the World Trade Center towers


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Giambologna’s Neptune, Bologna


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SensoryIntegration

InternalMap

Balance Depends on Sensory Information

Vision

Vest.

Somat.

Sensory Information

Movements Stimuli


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BiofeedbackDevice

Biofeedback Augments Sensory Information

SensoryIntegration

InternalMap


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Biofeedback: State of the Art


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The architecture of a BF system


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Biofeedback Device Components

BiofeedbackDevice

SENSINGAccelerometers, Gyroscopes, Force Plates, etc…

PROCESSINGPCs, Laptops, PDAs, IPODs, etc…

REPRESENTATIONEarphones, Monitors, Tactors, etc…


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Biofeedback Experiments


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An Accelerometry-based System for Balance Improvement Using Audio-biofeedbackChiari et al., IEEE Trans Biomed Eng, 2005

Our AUDIO-Biofeedback Device

SENSINGBi-axial Accelerometer ADXL203 Analog Device

PROCESSINGLaptop Commercial Toshiba 2.0GHz

REPRESENTATIONEarphones Commercial Maxell HP-550

ML

AP

Dev

ice

for c

ondi

tioni

ng b

alan

ce a

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otor

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and

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ent A

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Processing & Representation

Volume Modulation

Frequency Modulation



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Volume Modulation

Balance Modulation


Processing & Representation


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Sensing

• Audio-BF can provide similar information as one otolith:

– If the trunk/head moves slowly, primarily gravitational information is provided

– If the trunk/head moves quickly, primarily acceleration information is provided

• Continuous Audio-BF sound also provides trunk velocity information (critical)


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Visual and Audio Biofeedback

Effects of Linear versus Sigmoid Coding of Visual or Audio Biofeedback for the Control of Upright Stance

M. Dozza et al., IEEE Trans Neural Syst Rehab Eng, 2006


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Audio-Biofeedback During Quiet Stance- 9 bilateral vestibular loss and 9 controls subjects

(55yrs[38-73], 55yrs[33-71], respectively)

- Standing

- In 6 different conditions:

1) Eyes closed

2) Eyes closed with audio BF

3) Eyes open on foam

4) Eyes open on foam with audio BF

5) Eyes closed on foam

6) Eyes closed on foam with audio BF

- Each condition was repeated 3 (BVL) or 5 (Controls) times in random order

- Each trial was 60 seconds long

- Acceleration and center-of-pressure were recorded

- Feedback variable: Acc-L5

Exp.2 -Protocol:


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Audio-biofeedback Improves Balance In Patients with Bilateral Vestibular LossDozza et al., Arch Phys Med Rehab, 2005

• Improve balance (Sway Area decreases)• Increase control (Mean Velocity increases)

Audio-Biofeedback During Quiet Stance


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Auditory Biofeedback Substitutes for Loss of Sensory Information in Maintaining Stance Dozza et al., Exp Brain Res, 2007


The less sensory information was available the more subjects benefited from ABF


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0 0.1 0.2 0.3 0.40

10

20

30

40Sway reduction induced by ABF

1

2

3

4

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VOR gain

% COP-RMS reduction

8

Auditory Biofeedback Substitutes for Loss of Sensory Information in Maintaining Stance Dozza et al., Exp Brain Res, 2007


The less vestibular information was available the more subjects benefited from ABF

NO ABF ABF


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- 8, healthy, young subjects (23yrs±3.04)

- Standing on foam with eyes closed


1) With audio BF

2) Without audio BF

- Each condition was repeated 5 times (random order)


- Acceleration and center of pressure were recorded


Audio-Biofeedback During Quiet StanceExp.3a -

Protocol:


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Stabilogram Diffusion Analysis

• Examination of the structural properties of the COP and the EMG activity support the hypothesis that ABF does not induce an increased stiffness(and hence more co-activation) in leg muscles, but rather helps the brain to actively change to a more feedback-based control activity over standing posture

(L. Chiari et al., Hum Mov Sci, 2000)

Influence of a Portable Audio-Biofeedback Device on Structural Properties of Postural SwayDozza et al., J Neuroeng Rehab,2005



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Increase in postural stability is not at the expense of leg muscular activity, which remains almost unchanged

Influence of a Portable Audio-Biofeedback Device on Structural Properties of Postural SwayDozza et al., J Neuroeng Rehab,2005



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Direction Specificity in Quiet Stance

- 10, healthy, young subjects (33yrs±7)

- Standing with eyes closed


1) Audio BF only in Medial-Lateral direction

2) Audio BF only in Anterior-Posterior direction

3) No audio BF




Exp.3b -Protocol:


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• This suggests that sway reduction is not the consequence of a simple passive mechanism, such as body stiffness, or the consequence of a task involving a higher attentional demand, but rather the consequence of active control from the central nervous system.

• Using direction-specific, ABF information, subjects reduced their sway in the specific direction of the audio-biofeedback by increasing the frequency of their postural corrections in the specific direction of the biofeedback.

Direction Specificity in Quiet Stance

Direction specificity of audio-biofeedback for postural swayDozza et al., Hum Mov Sci (under revision)


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Visual and Audio Biofeedback- 8, healthy, young subjects (23yrs±3.0)

- Standing on foam


1) Eyes closed with audio BF (linear coding)

2) Eyes closed with audio BF (sigmoid coding)

3) Eyes open with visual BF (linear coding)

4) Eyes open with visual BF (sigmoid coding)

5) Eyes closed (control for condition 1-2)

6) Eyes open with random visual BF (control for condition 3-4)

- Each condition was repeated 5 times (random order)



- Feedback Variable: Acc-L5

Exp.4 -Protocol:


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Visual Biofeedback Audio Biofeedback

Visual and Audio Biofeedback




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Linear and Sigmoid Coding




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Audio vs Visual BF : effects on Acceleration- These results suggest that both the different sensory channel (audio and visual) and different coding function (linear and sigmoid) chosen to represent the BF information, may influence the effectiveness of BF.

-Sigmoid coding of audio BFinformation was more effective than linear coding in reducing sway.

- Linear coding of visual BFinformation was more effective than sigmoid coding in reducing sway




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Audio vs Visual BF : effects on Center of Pressure

- An inverted pendulum model (pure ankle strategy) can explain the reduction of both acceleration and COP SD found using sigmoid audio BF.

- However, in order to explain the opposite behavior of acceleration and COP standard deviations found with visual BF, it is necessary to use a multi-segmental model.

- Thus, subjects may have preferred a pure ankle strategy in response to sigmoid audio BF and applied a higher contribution of hip movements in response to visual BF.


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ABF has a Tuning-Fork effect?• Platform rotation:

6 deg, 1 deg/s

• BVL subject

PRE ABF

WITH ABF

POST ABF

Plat. Rotation

4 8 12 16 Time [s]

CO

M [d

egre

e]

0

-4

-2

2

4

Intervention to avoid fall


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Audio, which Audio?

- 13 healthy subjects, (33±7 yrs, 175±10 cm, 78±18 Kg).

- Stance perturbed in ML plane by pseudorandom rotation (W. D. T. Davies 1970) of a force plate with a 4-degree peak-to-peak amplitude over a frequency range of 0.017 to 2.2 Hz

- 3 blocks with 5 conditions (4 ABF modalities + 1 control)

- Data recorded: ML accelerations (L5 and C7), ML center of pressure, hip and shoulder ML position.

- Analysis of root mean square distance of acceleration and center of pressure over time in all conditions.

- Feedback variable: COP-ML

- Comparison of effect of learning and ABF

Exp.5 -Protocol:


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What is the most effective type of audio-biofeedback for postural motor learning?Dozza et al., Motor Control (in press)

Audio, which Audio?

4 ABF modalities

A: ABF coding both the magnitude and direction (full information) of COP displacement.

B: ABF coding only the magnitude of COP displacement.

C: ABF coding only direction of COP displacement.

D: ABF coding only for exceeding the RT (alarm).


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Averaged SD of A: center of pressure, and B: acceleration at L5 level in all five conditions tested. Asterisks indicate significant difference (p<0.05) from control condition

Audio, which Audio?



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Audio, which Audio?


• Initial improvement is proportional to the information content of ABF

• Both with and without BF postural motor learning overtime is evident

• BF is useful even after spontaneous motor learning

Ceiling Effect?


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ABF-based vs spontaneous motor learning

Postural Transfer Function (Peterka, J.Neurophysiol., 2002) analysis highlighted some differences among the mechanisms by which motor learning and ABF-based learning caused sway reduction once motor learning occurred.

Spontaneous motor learning and audio-biofeedback affect different frequency ranges of postural control during standing on a randomly rotating surface

Dozza et al., J Neurophysiol, November 2007 (submitted)


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Spontaneous motor learning and audio-biofeedback affect different frequency ranges of postural control during standing on a randomly rotating surface

Dozza et al., J Neurophysiol, November 2007 (submitted)

ABF-based vs spontaneous motor learning

Motor learning favored PTF gain reduction in the 0.2-1 Hz interval and PTF phase increase above 0.8 Hz whereas ABF favored PTF gain reduction for the frequencies below 0.2 Hz and increase of PTF phase below 0.4 Hz.


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An unexpected result of this study was that subjects did not reduce equally the PTF gain at all frequencies overtime but, instead, had a pretty narrow and specific range of frequencies that they tended to reduce the most.

This narrow range matches the range of frequencies where a small peak, similar to a resonance peak in a second-order system, was also evident in the PTF. The presence of such peaks in a transfer function normally determines more instability for the system in the range of frequencies where the peak is.

As a consequence, the reduction of gain in a narrow range of frequencies matching the frequencies of the PTF gain peak seems aimed at improving the system stability where it was more needed. In other words, the peak of reduction showed by the subjects in some narrow range of frequencies may have been favored by the system being a priori more instable in that very range of frequencies.

These results suggest that 1) postural responses to low-frequency perturbation were faster when using ABF; and 2) postural responses to high-frequency perturbation became faster with repetition of the task.


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BF Training for SCI PatientsExp.7 -

Protocol:

0 10 20 30 40 50 60-20

-15

-10

-5

0

5

10

15

20

TEMPO (s)

AC

CE

LER

AZI

ON

E A

P (m

m/s

2 )

RAPPRESENTAZIONE GRAFICA DEL SEGNALE DI ACCELERAZIONE IN DIREZIONE AP CON E SENZA VBF

Acc. AP senza VBFAcc. AP con VBFsoglia AP con VBFsoglia AP con VBF

- 6 SCI patients (34±12 yrs), lesional level C6-T6

- Wheelchair sitting posture

- 15 sessions of 30’ each, 4 conditions (VBF, ABF, AVBF + 1 control)

- Feedback variable: Acc-Trunk


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First trial Last trial


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BF for Dynamic Balance Tasks


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Effects of practicing tandem gait with and without vibrotactile biofeedback in subjects withunilateral vestibular loss

Dozza et al., J Vest Res, 2007


89

Summary of the Conclusions - 1

- Using Audio-BF both bilateral vestibular loss and control subjects improve balance by increasing postural control corrections.

- Audio-BF is the most helpful when the least sensory information is available.

- Efficacy of Audio-BF in reducing sway is related to the degree of severity of the bilateral vestibular loss.

- Sway reduction using Audio-BF is not simply achieved by increasing body stiffness.

- Both the effectiveness of the BF information in reducing sway and the strategy favored by the subjects to control the BF signal may depend on the BF coding function and presentation.


90

- Higher amount of Audio-BF information results in higher postural stability in naïve subjects. However, overtime, motor learning normalizes the effects of the different amount of BF information. Nevertheless, motor learning does not completely neutralize the effect of ABF which still improves motor performances even after subjects learn the task.

- Audio-BF reduced the gain of the PTF especially at low frequencies: ABF affects prevalently the low frequencies of sway ( below 0.4 Hz) whereas spontaneous motor learning affects prevalently the high frequencies of sway (above 0.4 Hz)

Summary of the Conclusions - 2


91

• L. Chiari, M. Dozza, A. Cappello, F.B. Horak, V. Macellari and D. Giansanti, “An accelerometry-based system for balance improvement using audio-biofeedback”, IEEE Trans Biomed Eng 52(12), December 2005.

• M. Dozza, L. Chiari, B. Chan, L. Rocchi, F.B. Horak and A. Cappello, “Influence of a Portable Audio-Biofeedback Device on Structural Properties of Postural Sway”, J Neuroengineering Rehabil 2:13, 31 May 2005.

• M. Dozza, L. Chiari and F.B. Horak, “Audio-biofeedback improves balance in patients with bilateral vestibular loss”, Arch Phys Med Rehab 86(7):1401-3, July 2005.

• M. Dozza, L. Chiari, F. Hlavacka, F.B. Horak and A. Cappello, “Effects of Linear versus Sigmoid Coding of Visual or Audio Biofeedback for the Control of Upright Stance”, IEEE Trans Neural Syst Rehab Eng 14(4):505-12, December 2006.

• M. Dozza, F.B. Horak and L. Chiari, “Auditory Biofeedback Substitutes for Loss of Sensory Information in Maintaining Stance”, Exp Brain Res178(1):37-48, March 2007.

Publications


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• M. Dozza, C. Wall III, R.J. Peterka, L. Chiari, F.B. Horak, “Effects of Practicing Tandem Gait with and without Vibrotactile Biofeedback in Subjects with Unilateral Vestibular Loss”, J Vest Res, 17(4):195-204, 2007.

• M. Dozza, L. Chiari, R.J. Peterka, C. Wall III, F.B. Horak, “What is the most effective type of audio-biofeedback for postural motor learning?”, Motor Control, (in press).

• M. Dozza, L. Chiari, R.J. Peterka, C. Wall III, F.B. Horak, “ Spontaneous motor learning and audio-biofeedback affect different frequency ranges of postural control during standing on a randomly rotating surface”, J Neurophysiol, (submitted).

• M. Dozza, F.B. Horak, L. Chiari and J. Frank, “Direction specificity of audio-biofeedback for postural sway”, Hum Mov Sci (under revision).

The use of wearable inertial devices The use of wearable inertial devices to detect early (functional) to detect early (functional)

biomarkers of Parkinson’s diseasebiomarkers of Parkinson’s disease

Introduction

Several studies have shown that subjects with advanced Parkinson’s disease (PD) exhibit ‘abnormal’ sway during quiet standing.

Such abnormalities have not yet been reported in patients with early symptoms of PD (subclinical signs).

We hypothesize that measures provided from inertial sensors mounted on different body segments could represent a good tool to quantify spontaneous, multisegmental body sway and to disclose slight changes in postural coordination.

Discussion & Conclusions

Our results prove that postural control is compromised in patients with early PD, and that wearable inertial sensors could be useful for monitoring patients’ progression in the home environment.

Accelerometers could provide sensitive measures of:- the pathology- its progression- the effect of drugs


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ISPGR 2009Palazzo Re Enzo, Bologna, Italy

19th International ConferenceJune 21st – 25th, 2009


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SOCIAL ACTIVITIES Cooking lessons<

Hiking excursions<Enogastronomic tours<

Ferrari Museum<Accompanying person program<

TOPICS>Neurophysiology of Sensorimotor Control>Cognitive, Attentional, and Emotional Influences>Learning, Plasticity and Compensation>Posture and Gait from Newborn to Elderly>Coordination of Posture and Movement>Cerebral Palsy>Basal Ganglia Disorders>Stroke>Ataxia>Vestibular Physiopathology>Orthopedic Diseases >Sensory Training and Biofeedback >Habilitation & Rehabilitation>Falls and Fall Prevention>Pharmacological Effects>Modelling & Biomechanics >Tools and Methods for Posture and Gait Analysis>Activity Monitoring during Daily Living>Sport, Exercise and Ergonomics>Prosthetics and Orthotics>Emerging Technologies: from Robots

to Implantable Neuroprostheses

CALL FOR YES/NO DEBATES A selected list of ‘hot-topics’ will be proposed

for an entertaining and lively debate

RELEVANT DATES 1 October 2008: abstract submission opening<

15 December 2008: abstract submission deadline<yes/no debate proposal deadline<

1 March 2009: notification of acceptance<1 April 2009: early registration deadline<

VENUE Palazzo Re Enzo, Piazza Nettuno 1/c, Bologna


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Open Positions @ UNIBO

2007-2010

Sensing and Action to Sensing and Action to support mobility in Ambient support mobility in Ambient

Assisted LivingAssisted Living

2007-2009

PhD, PostDocs: Electronics, Automation, Mechanical, Biomedical Eng.; Neuroscientists; Kinesiologists


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Neurological Sciences InstituteOregon Health & Science University

Beaverton (OR), USA

Fay B. Horak, PhD, PTRobert J. Peterka, PhD

Acknowledgements

Dept. of Electronics, Computer Science, and Systems, Università di Bologna,

Bologna, Italy

Martina ManciniMarco Dozza, PhDLaura Rocchi, PhD

Angelo Cappello, PhDLuca Benini, PhD

www.starter-project.com www.sensaction-aal.eu

Kinetics Foundation


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