Pravin NairDecember 12, 2003Slide 1 of 30
DEVELOPMENT OF QUANTITATIVE MEASURES FOR CHARACTERIZATION OF UPPER LIMB DYSFUNCTION
Pravin Nair
Advisor : Dr. Venkat Krovi
Mechanical and Aerospace Engineering Department
State University of New York at Buffalo.
Pravin NairDecember 12, 2003Slide 2 of 30
Presentation Overview
Motivation- Stroke, Rehabilitation and Diagnosis- Research Goals
Background- Robotic Therapy Devices
Implementation Framework- Hardware and Software Integration- Parameterized Exercise Protocols
Experiments - Design of Experiments
Results and Analysis- Mathematical Preliminaries- Quantitative Measures- Analysis of Obtained Data
Conclusions and Future Work - Summary- Work in Progress
Pravin NairDecember 12, 2003Slide 3 of 30
Stroke and Rehabilitation• when a blood clot blocks a blood vessel or artery, or when a
blood vessel breaks, interrupting blood flow to an area of the brain, causing brain cells to die.
• Each year, over 750,000 people experience a new or recurrent stroke, leading to motor disability and upper limb (UL) dysfunction [NSA].
• Rehabilitation A goal-oriented process, which enables individuals with impairments to reach their optimal physical, mental and/or social functional level.
• Functional recovery linked to the duration, frequency, regularity and intensity of the rehabilitation therapy [1-5].
• Diagnosis A term which names the primary dysfunction towards which the therapist directs the Rehabilitation regimen
Motivation Background Implementation Framework Experiments Results & Analysis Future Work
STROKE
Rehabilitation
References [1-5] listed in slide 32
Diagnosis
Pravin NairDecember 12, 2003Slide 4 of 30
Rehabilitation Regimen Implementation Issues
1. Careful characterization of the functional impairment.
• Variability within population
• Variability due to disease progress
• Subjective v/s Objective Assessment
2. Overall economic viability and logistics of deployment.
Accurate and Ongoing Assessment
Infrastructure Access/Costs v/sFunctional Recovery
Logistics:• Inpatient• Outpatient• Home-based
Exercise Regimen:• Free-Motion• Machine-Assisted
Motivation Background Implementation Framework Experiments Results & Analysis Future Work
Pravin NairDecember 12, 2003Slide 5 of 30
Goal of the Research Work
• A low-cost, home-based diagnostic and rehabilitation tool.
• Implementation as an immersive Personal Movement Trainer:
• Adequacy for quantitative assessment and ability to differentiate between users.
Motivation Background Implementation Framework Experiments Results & Analysis Future Work
Target Audience: People with Upper Limb (UL) dysfunction due to Stroke
COTS + Virtual Environment + Path Devices Library
Virtual Driving Environment
Pravin NairDecember 12, 2003Slide 6 of 30
Constraint-Induced Therapy
Constraint Induced Therapy The patient’s less impaired arm is restrained, and the patient intensively practices moving the more impaired arm, with feedback from a therapist.
• Improves functional use
• Expands cortical representation of the exercised limb.
• Needs continuous monitoring
• Needs specialized equipment or crude methods for restraining the less impaired limb
Advantages:
Disadvantages:
Constraint Induced Therapy
Motivation Background Implementation Framework Experiments Results & Analysis Future Work
Pravin NairDecember 12, 2003Slide 7 of 30
Current Technology and their Shortcomings
1.Current functional assessment (diagnostic testing) is subjective or semi-quantitative
2. Existing Robotic Therapy Devices (low-cost, portable, force-feedback devices) are specialized and concentrate on rehabilitation (as opposed to diagnosis and rehabilitation).
• MIT-MANUS• Rutgers Master II (RMII)• ARM Guide, JAVA Therapy• PHANTOM-based diagnosis
Examples of existing Robotic Diagnosis and Rehabilitation devices
Motivation Background Implementation Framework Experiments Results & Analysis Future Work
Pravin NairDecember 12, 2003Slide 8 of 30
Existing Specialized Robotic Therapy Devices
MIT-MANUS [1] Rutgers Master II (RMII) [2]
ARM Guide [3]
[1] M. Aisen, H. Krebs, N. Hogan, F. McDowell, and B. Volpe. “The effect of robot-assisted therapy and rehabilitative training on motor recovery following stroke,” Arch . Neurol., vol. 54, pp. 443–446, Apr.1997.
[2] V. Popescu, G. Burdea, M. Bouzit, and V. Hentz. “A Virtual-Reality-Based Telerehabilitation System with Force Feedback,” IEEE trans. on Information Technology in Biomedicine, vol. 4, no.1, March 2000. [3] D. Reinkensmeyer, B. Schmit, and W. Rymer, “Assessment of active and passive restraint during guided reaching after chronic brain injury,” Ann. Biomed. Eng., vol. 27, pp. 805–814, 1999.
Motivation Background Implementation Framework Experiments Results & Analysis Future Work
Pravin NairDecember 12, 2003Slide 9 of 30
“JAVA Therapy” COTS device [1]
Existing COTS-device and a Specialized Diagnostic Tool
PHANTOM-based diagnostic tool [2]
[1] D. Reinkensmeyer, C. Painter, S. Yang, E. Abbey, and B. Kaino, “An Internet-Based, Force-Feedback Rehabilitation System for Arm Movement after Brain Injury,” Proceedings of Technology and Persons with Disabilities Conference, 2000.
[2] A. Bardorfer, M. Munih, A. Zupan, and A. Primožič. “Upper Limb Motion Analysis using Haptic Interface,” IEEE/ASME transactions on Mechatronics, Vol.6, No.3, September 2001.
Motivation Background Implementation Framework Experiments Results & Analysis Future Work
Pravin NairDecember 12, 2003Slide 10 of 30
Our Hypothesis
Emphasizes:• COTS force-feedback devices• Immersive environment• Parameterized exercises
At Present:
1. One such device developed
2. Diagnostic capabilities only
GAMING DEVICES
Functional Assessment &
Motor Rehabilitation
InterfaceHardware
EXERCISE-PROTOCOLS
Low-Cost Mass Produced
Devices
Immersive Virtual
Environment
ParameterizedTherapies
IMPLEMENTATION FRAMEWORK
DESKTOP/LAPTOP PC
Motivation Background Implementation Framework Experiments Results & Analysis Future Work
Pravin NairDecember 12, 2003Slide 11 of 30
Overall Implementation
User Input
pedals
Vehicle Visualization
Immersive Driving Scenario
User Input from wheel &
pedals
Vehicle Kinematics
Parameterized Exercise Routines
Paths parameterized by amplitude and frequency
Motivation Background Implementation Framework Experiments Results & Analysis Future Work
Pravin NairDecember 12, 2003Slide 12 of 30
Virtual Vehicle Model
Knife edge kinematic model of a differentially driven wheeled vehicle.
Motion of the origin of the body-fixed reference frame w.r.t. the inertial frame:• Vx in the body-fixed x-direction• Vy in the body-fixed y-direction ( Vy = 0)
• angular velocity ω
The user is considered to be driving a differential-drive vehicle which can be modeled using the knife-edge model.
.
.
.
.
.
cos 0
sin 0
0 1
1/ / 2
1/ / 2l
r
x
yV
R Rb
R Rb
Motivation Background Implementation Framework Experiments Results & Analysis Future Work
Pravin NairDecember 12, 2003Slide 13 of 30
Simulink Implementation of the System
Simulink Block diagram of the system implemented
Data Collection
Vehicle Kinematics
Data Output
Motivation Background Implementation Framework Experiments Results & Analysis Future Work
Pravin NairDecember 12, 2003Slide 14 of 30
Visualization Aspect of the system
Example of a 2D GUI which allows conduct of the experiment and provides immediate relevant statistical feedback.
Examples of 3D visual interfaces for our Virtual Driving Environment (a) with simple parametrically generated paths; (b) with realistic roads from a database.
Motivation Background Implementation Framework Experiments Results & Analysis Future Work
Pravin NairDecember 12, 2003Slide 15 of 30
Testing Procedure
1. Subjects are “healthy”
2. Arm angles fixed at:
θ1 = 45°
θ2 = 60°
3. D1 and D2 adjusted to maintain a fixed offset
Assumptions and Standards :
Experimental Test Setup,
Schematic with relevant parameters
Motivation Background Implementation Framework Experiments Results & Analysis Future Work
Pravin NairDecember 12, 2003Slide 16 of 30
Guide the “vehicle” along parametrically generated paths, remaining as close as possible to the center line, with 3 preset forward speeds.
TASK
Testing Procedure (Cont:)
2D GUI Patient/Therapist Interface
Parametric library of labyrinthine maze-style paths and sinusoidal paths used for the diagnostic testing routine
Motivation Background Implementation Framework Experiments Results & Analysis Future Work
Pravin NairDecember 12, 2003Slide 17 of 30
x-coord. y-coord.
0.0025109 0.0747880.003825 0.0821720.005139 0.0895560.0065688 0.0969180.0079985 0.104280.0094857 0.111630.01103 0.118970.012632 0.12630.014263 0.13362
-0.8 -0.6 -0.4 -0.2 0 0.2 0.4 0.60
0.5
1
1.5
2
2.5
3
3.5
4
Desired Path
Actual Path
Sample collected data
Plot of the user generated and actual paths
Movie file depicting the testing routine
Testing Procedure (Cont:)
Motivation Background Implementation Framework Experiments Results & Analysis Future Work
Pravin NairDecember 12, 2003Slide 18 of 30
Planar Curve and Cubic Spline
2 3( )i i i i iy t a b t c t d t
ˆ ˆ( )t x t i y t j R
0
( ) ( ) ( )t
t
s t t t dt R R
( ) ˆd s
ds
RT
ˆˆd
ds
TN
( )( ) d dTR s
ds dss
Planar Curve
Arc Length
Curve Tangent
Curvature of a
Curve
Curve Normal
Cubic Spline
X
Y
R(t)
T̂
N̂
Where, (0)
(0)
3( (1) (0)) 2 (1)
2( (0) (1)) (1)
[0,1], 0,1,...,
i i
i i i
i i i i i
i i i i i
a y
b y D
c y y D y
d y y D y
t i n
Where, is the tangential angle
Motivation Background Implementation Framework Experiments Results & Analysis Future Work
Pravin NairDecember 12, 2003Slide 19 of 30
0 5 10 15 20 25 30 35 40 45 50-10
-5
0
5
10Signal Corrupted with Zero-Mean Random Noise
time (seconds)
0 50 100 150 200 250 300 350 400 450 5000
50
100
150Frequency content of y
frequency (Hz)
Fourier Mathematics
)1( ,)(1
][)1)(1(2
1
NjekZN
jz N
kjiN
k
)1( ,][]][[][)1)(1(2
1
NkejzjxDFTkZ N
jkiN
j
N
k
N
j
kZN
jz1
2
1
2 ][1
][
Original Periodic Signal
Discrete Fourier Transform
Spectral Energy
Motivation Background Implementation Framework Experiments Results & Analysis Future Work
Pravin NairDecember 12, 2003Slide 20 of 30
-0.8 -0.6 -0.4 -0.2 0 0.2 0.4 0.60
0.5
1
1.5
2
2.5
3
3.5
4
Desired Path
Actual Path
Performance MeasuresA quantity which explicitly expresses some desirable characteristic of an individual which helps in categorization of the (motor) ability/skill of that individual.
1. Error Value Parameter (EVP)
Difference between the desired and actual path at each time instant.
Error Value Parameter (EVP)Curvature-Based Performance Measure
Discrete Fourier Transform-Based Error Measure
Our Measures
Motivation Background Implementation Framework Experiments Results & Analysis Future Work
Pravin NairDecember 12, 2003Slide 21 of 30
Principal Harmonic
0 5 10 15 20 25 30 350
0.2
0.4
0.6
0.8
1
1.2
1.4
1.6
Frequency
Ma
ga
nit
ud
e
Frequency Spectrum
Secondary Harmonics
Performance Measures (cont:)
2. Curvature-Based Performance Measure
Comparison between the desired and actual path curvatures at for the corresponding arc length.
3
2 2 2
' '' ' ''
' '
x y y x
x y
2. Discrete Fourier Transform-Based Error Measure
Measure
UsefulEnergyDFT
TotalEnergy
2
2
1
[ ]
1[ ]
k pMeasure N
k
Z k
DFTZ k
N
2 3
2 3
x x x x
y y y y
x a b t c t d t
y a b t c t d t
Where,
Or,
Motivation Background Implementation Framework Experiments Results & Analysis Future Work
Pravin NairDecember 12, 2003Slide 22 of 30
1 2 3 4 50
2
4
6
8
10
12
Subject
Tim
e (
Se
c)
Time taken to complete the task
LowMediumHigh
Result Analysis
0 2 4 6 8 10 120
0.1
0.2
0.3
0.4
0.5
0.6
0.7
Time (sec)
Err
or
Va
lue
Pa
ram
ete
r (E
VP
)
Time v/s Error Value Parameter (EVP)
data1data2data3data4data5data6
Subject 4
Subject 2
Subject 1
Subject 3
Subject 5
Plot showing the EVP plotted against the time value collected from the subjects for ‘Sine1’ at ‘Low’ speed.
Graph showing time taken by the subjects to traverse the path ‘Sine1’ at all speeds.
Motivation Background Implementation Framework Experiments Results & Analysis Future Work
Pravin NairDecember 12, 2003Slide 23 of 30
0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5-4
-3
-2
-1
0
1
2
3
Arc Length
Cur
vatu
re
Plot of Curvature v/s Arc Length for all Subjects superimposed over the Expected Curvature
Subject 4
Subject 2
Subject 1
Subject 5
Expected Curvature
Subject 3
Results (cont:)
Plot of curvatures of the user generated curve superimposed over the expected curvature.
Motivation Background Implementation Framework Experiments Results & Analysis Future Work
Pravin NairDecember 12, 2003Slide 24 of 30
Results (cont:)
0 1 2 3 4 5 6 7 8 9 100
0.05
0.1
0.15
0.2
0.25
0.3
Frequency
Mag
nitu
de
Frequency spectrum of all users traversing 'Sine1' path at a 'Low' speed
Subject 4
Subject 2
Subject 1
Subject 5
Subject 3
Subject No. Energy Ratio
1 0.2364
2 0.2297
3 0.2424
4 0.2355
5 0.2575
Plot of Frequency spectrum of user generated curves at ‘Low’ speed on ‘Sine1’ path.
Table of Energy Ratios
Motivation Background Implementation Framework Experiments Results & Analysis Future Work
Pravin NairDecember 12, 2003Slide 25 of 30
Results (cont:)
0 2 4 6 8 10 120
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
Time (sec)
Err
or V
alue
Par
amet
er (
EV
P)
Time v/s Error Value Parameter (Subject 2)
Trial 2
Trial 1
0 2 4 6 8 10 120
0.05
0.1
0.15
0.2
0.25
0.3
0.35
0.4
0.45
Time (sec)
Err
or V
alue
Par
amet
er (
EV
P)
Time v/s Error Value Parameter (Subject 1)
Trial 1
Trial 2
0 2 4 6 8 10 120
0.05
0.1
0.15
0.2
0.25
0.3
0.35
0.4
Time (Sec)
Err
or V
alue
Par
amet
er (
EV
P)
Time v/s Error Value Prameter (Subject 3)
Trial 1
Trial 2
0 2 4 6 8 10 120
0.2
0.4
0.6
0.8
1
1.2
1.4
Time (sec)
Err
or V
alue
Par
amet
er (
EV
P)
Time v/s Error Value Parameter (Subject 4)
Trial 2
Trial 1
Plots of comparison of subject performance (Error Value Parameter) in two trials- Trial 1: Initial test and Trial 2: Test after 6 months.
Motivation Background Implementation Framework Experiments Results & Analysis Future Work
Pravin NairDecember 12, 2003Slide 26 of 30
Results (cont:)
0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5-2.5
-2
-1.5
-1
-0.5
0
0.5
1
1.5
2
2.5Curvature v/s Arc Length (subject 1)
Arc Length
Cur
vatu
re
Trial 1
Trial 2
0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5-4
-3
-2
-1
0
1
2
3Curvature v/s Arc Length (subject 2)
Arc Length
Cur
vatu
re
Trial 2
Trial 1
0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5-1.5
-1
-0.5
0
0.5
1
1.5
2Curvature v/s Arc Length (subject 3)
Arc Length
Cur
vatu
re
Trial 2
Trial 1
0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5-2.5
-2
-1.5
-1
-0.5
0
0.5
1
1.5
2
Arc Length
Cur
vatu
re
Curvature v/s Arc Length (Subject 4)
Trial 2
Trial 1
Plots of comparison of subject performance (Curvature Comparison) in two trials- Trial 1: Initial test and Trial 2: Test after 6 months.
Motivation Background Implementation Framework Experiments Results & Analysis Future Work
Pravin NairDecember 12, 2003Slide 27 of 30
Conclusions
Considerable promise for improving the speed, resolution and quality of diagnosis.
Successful development, implementation and testing of a low-cost diagnostic tool
Preliminary tests display the potential of the set-up as a diagnostic tool
Motivation Background Implementation Framework Experiments Results & Analysis Future Work
Pravin NairDecember 12, 2003Slide 28 of 30
Continuing/Future Work
Test the tool with people with UL dysfunctions
Provide force-feedback to the subjects
Develop a 3-D interface as patient feedback to the therapist
Add strength training/recovery aspects to the tool
Network the tool through the internet
Motivation Background Implementation Framework Experiments Results & Analysis Future Work
Pravin NairDecember 12, 2003Slide 29 of 30
Questions ?
Pravin NairDecember 12, 2003Slide 30 of 30
Thank You
Pravin NairDecember 12, 2003Slide 31 of 30
References
1. M. Aisen, H. Krebs, N. Hogan, F. McDowell, and B. Volpe. “The effect of robot-assisted therapy and rehabilitative training on motor recovery following stroke,” Arch. Neurol., vol. 54, pp. 443–446, Apr.1997.
2. H. Krebs, N. Hogan, M. Aisen, and B. Volpe. “Robot-Aided Neurorehabilitation,” IEEE transactions on Rehabilitation Engineering, vol. 6, no. 1, March 1998.
3. B. Volpe, H. Krebs, N. Hogan, L. Edelsteinn, C. Diels, and M. Aisen. “Robot training enhanced motor outcome in patients with stroke maintained over 3 years,” Neurology, vol. 53, pp. 1874–1876, 1999.
4. K. Kwakkel et al. “Effects of intensity of rehabilitation after stroke, a research synthesis,” Stroke, vol. 28, no. 8, pp. 1550–1556, 1997.
5. P. Langhorne, R. Wagenaar, and C. Partridge. “Physiotherapy after stroke: More is better?,” Physiotherapy Res. Int., vol. 1, pp. 75–88, 1996.
Pravin NairDecember 12, 2003Slide 32 of 30
Curvature Comparison Example Example
2
2 2 2
ˆsin( )( )
1 cos ( )
aw t iR s
a w t
sin( )x a t y t
ˆ ˆ( ) sin( )R t a t i t j
ˆ ˆ( ) cos( )R t aw t i j
( )s t R R dt
2 2 2( ) ( ) cos ( ) 1R t R t a w t
0
2 2 2( ) 1 cos ( )t
t
s t a w t dt
2 2 2( ) 1 cos ( )ds
s t a w tdt
2 2 2
ˆ ˆ( ) cos( )( )
( ) 1 cos ( )
dR dR dt R t aw t i jR s
ds dt ds s t a w t
( )R s
2
2 2 2
sin( )
1 cos ( )
aw t
a w t
Motivation Background Performance Measures Implementation Framework Experiments & Results Future Work
Pravin NairDecember 12, 2003Slide 33 of 30
Discrete/Fast Fourier Transform Analysis
Principal Harmonic
0 5 10 15 20 25 30 350
0.2
0.4
0.6
0.8
1
1.2
1.4
1.6
Frequency
Ma
ga
nit
ud
e
Frequency Spectrum
Secondary Harmonics
Frequency Spectrum of a signal
_UsefulEnergy
FFT MeasureTotalEnergy
Where, Useful Energy is the energy captured by the more significant peaks of the Fast Fourier Graph.
Motivation Background Performance Measures Implementation Framework Experiments & Results Future Work
Pravin NairDecember 12, 2003Slide 34 of 30
Continuing Work
Motivation Background Performance Measures Implementation Framework Experiments & Results Future Work
Pravin NairDecember 12, 2003Slide 35 of 30
Detailed Simulink Block Diagram
Pravin NairDecember 12, 2003Slide 36 of 30
Functional Interaction
Therapist’s Interface
Virtual Environment
Graphical Display
Therapist
Device Manager
Subject
Internet
User Interface Internet
Functional interaction of the visualization, programming and data acquisition components.
Pravin NairDecember 12, 2003Slide 37 of 30
Mean Deviation Result Table
Mean deviation values for the subjects at all the 3 speeds for the 3 sinusoidal paths.
Motivation Background Performance Measures Implementation Framework Experiments & Results Future Work
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