chiari, lorenzo - intelligent assistive technologies for...
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Department of Electronics, Computer Science, and SystemsAlma Mater Studiorum – Università di Bologna
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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• 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
Patras - July 3, 2008 4th Summer School on Emerging Technologies in Biomedicine
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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)
Patras - July 3, 2008 4th Summer School on Emerging Technologies in Biomedicine
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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
Patras - July 3, 2008 4th Summer School on Emerging Technologies in Biomedicine
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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
Patras - July 3, 2008 4th Summer School on Emerging Technologies in Biomedicine
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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
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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
Patras - July 3, 2008 4th Summer School on Emerging Technologies in Biomedicine
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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
Patras - July 3, 2008 4th Summer School on Emerging Technologies in Biomedicine
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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
)
Patras - July 3, 2008 4th Summer School on Emerging Technologies in Biomedicine
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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
)
Patras - July 3, 2008 4th Summer School on Emerging Technologies in Biomedicine
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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
)
Patras - July 3, 2008 4th Summer School on Emerging Technologies in Biomedicine
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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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• 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
redits: Laura Rocchi (U
NIB
O)
Patras - July 3, 2008 4th Summer School on Emerging Technologies in Biomedicine
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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
redits: Laura Rocchi (U
NIB
O)
Patras - July 3, 2008 4th Summer School on Emerging Technologies in Biomedicine
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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
redits: Laura Rocchi (U
NIB
O)
Patras - July 3, 2008 4th Summer School on Emerging Technologies in Biomedicine
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Silicon Designs, Inc
adxl203
Some examples
adxl203
Credits: Laura R
occhi (UN
IBO
)
Patras - July 3, 2008 4th Summer School on Emerging Technologies in Biomedicine
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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
)
Patras - July 3, 2008 4th Summer School on Emerging Technologies in Biomedicine
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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
redits: Laura Rocchi (U
NIB
O)
Patras - July 3, 2008 4th Summer School on Emerging Technologies in Biomedicine
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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
Patras - July 3, 2008 4th Summer School on Emerging Technologies in Biomedicine
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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
)
Patras - July 3, 2008 4th Summer School on Emerging Technologies in Biomedicine
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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
)
Patras - July 3, 2008 4th Summer School on Emerging Technologies in Biomedicine
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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
)
Patras - July 3, 2008 4th Summer School on Emerging Technologies in Biomedicine
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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.
Patras - July 3, 2008 4th Summer School on Emerging Technologies in Biomedicine
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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
Patras - July 3, 2008 4th Summer School on Emerging Technologies in Biomedicine
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
nd m
otor
coo
rdin
atio
nD
evic
e fo
r con
ditio
ning
bal
ance
and
mot
or c
oord
inat
ion
Pat
ent A
pplic
atio
n: P
CT
/IB20
04/0
0167
9P
aten
t App
licat
ion:
PC
T /IB
2004
/001
679
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Processing & Representation
Volume Modulation
Frequency Modulation
An Accelerometry-based System for Balance Improvement Using Audio-biofeedbackChiari et al., IEEE Trans Biomed Eng, 2005
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Volume Modulation
Balance Modulation
An Accelerometry-based System for Balance Improvement Using Audio-biofeedbackChiari et al., IEEE Trans Biomed Eng, 2005
Processing & Representation
Patras - July 3, 2008 4th Summer School on Emerging Technologies in Biomedicine
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An Accelerometry-based System for Balance Improvement Using Audio-biofeedbackChiari et al., IEEE Trans Biomed Eng, 2005
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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)
Patras - July 3, 2008 4th Summer School on Emerging Technologies in Biomedicine
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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:
Patras - July 3, 2008 4th Summer School on Emerging Technologies in Biomedicine
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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
Audio-Biofeedback During Quiet Stance
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
67
VOR gain
% COP-RMS reduction
8
Auditory Biofeedback Substitutes for Loss of Sensory Information in Maintaining Stance Dozza et al., Exp Brain Res, 2007
Audio-Biofeedback During Quiet Stance
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
- In 2 different conditions:
1) With audio BF
2) Without audio BF
- Each condition was repeated 5 times (random order)
- Each trial was 60 seconds long
- Acceleration and center of pressure were recorded
- Feedback variable: Acc-L5
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
Audio-Biofeedback During Quiet Stance
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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
Audio-Biofeedback During Quiet Stance
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Direction Specificity in Quiet Stance
- 10, healthy, young subjects (33yrs±7)
- Standing with eyes closed
- In 3 different conditions:
1) Audio BF only in Medial-Lateral direction
2) Audio BF only in Anterior-Posterior direction
3) No audio BF
- Each trial was 60 seconds long
- Acceleration and center of pressure were recorded
- Feedback variable: Acc-L5
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
- In 6 different conditions:
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)
- Each trial was 60 seconds long
- Acceleration and center of pressure were recorded
- Feedback Variable: Acc-L5
Exp.4 -Protocol:
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Visual Biofeedback Audio Biofeedback
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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Linear and Sigmoid Coding
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 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
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
Patras - July 3, 2008 4th Summer School on Emerging Technologies in Biomedicine
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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
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?
What is the most effective type of audio-biofeedback for postural motor learning?Dozza et al., Motor Control (in press)
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Audio, which Audio?
What is the most effective type of audio-biofeedback for postural motor learning?Dozza et al., Motor Control (in press)
• 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
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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.
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- 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
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• 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