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Repetitive Control Based Tremor Suppression Using Electrical

Stimulation

Engin Hasan Copur

Dr. Bing Chu, Dr. Christopher Freeman,

Dr. Dina Shona Laila

University of Southampton

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Outline

What is a tremor? Tremor Suppression Techniques Objective Simulation Results Conclusion and Future Work

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What is a tremor?

Tremor is an approximately rhythmic, roughly sinusoidal involuntary movement

1.5 million patients in Europe have essential tremor (Sullivan et al., 2004)

Of these 1.5 million as many as one in three may have intention tremor (Louis et al., 2009)

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Tremor Suppression Techniques

Invasive Methods:

Stereotactic Thalamotomy

Deep Brain Stimulation (DBS)

Non-invasive Methods:

Pharmacological treatment

Non-pharmacological treatment

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Functional Electrical Stimulation (FES)

Previous treatment methods have some limitations

FES is potentially more effective and less dangerous than the others

An open challenge of using FES for tremor suppression is to employ a most effective closed-loop control algorithm in FES applications.

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Objective

In my study, repetitive control is used and compared with some other methods to examine whether repetitive control has more potential than the others for suppressing tremor or not.

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Simulation Results

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0 0.5 1 1.5 2 2.5 3 3.5-4

-3

-2

-1

0

1

2

3

4

5

6x 10

-3

Time (s)

Trem

or A

mpl

itude

Closed-loop SystemOpen-loop System

0 0.5 1 1.5 2 2.5 3 3.5-4

-3

-2

-1

0

1

2

3

4

5

6x 10

-3

Time (s)

Trem

or A

mpl

itude

Closed-loop SystemOpen-loop System

Time responses of output of closed-loop system with high-pass and band-pass filters

F

G

c

-+

�

V oluntar y motion signal, r T r emor signal, d

+Wrist Model

FilterGain

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Simulation Results

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0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2-0.03

-0.02

-0.01

0

0.01

0.02

0.03

Time(s)

Out

put o

f Clo

sed-

Loop

Sys

tem

Fs = 45Hz

Open-loop SystemRC w/o inner feedback systemRC with inner feedback system

0 2 4 6 8 10 12 14 16 18 20-0.02

-0.015

-0.01

-0.005

0

0.005

0.01

0.015

0.02

T ime (s )Tr

emor

Am

plitu

de

Gradient-based RC w/o inner loopGradient-based RC with inner loopOpen-Loop System

Time responses of output of closed-loop system with different repetitive control algortihms

Wrist Model

Repetitive Controller

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Conclusion or summary or future work

Conclusion Filters are able to remove tremor signal very slightly RC is more efficient than filters However both methods have some limitations

Future Work All simulations in this study will be tested experimentally The identification method of wrist model will be checked The studies will be expanded to design a more robust control

algorithm All methods may be tested on MS patients diagnosed with intention

tremor

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Thank you!

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References

Louis, E. D., Frucht, S. J., and Rios, E. (2009). Intention tremor in essential tremor: Prevalence and association with disease duration. Movement Disorders, 24(4):626–627. 4

Sullivan, K. L., Hauser, R. A., and Zesiewicz, T. A. (2004). Essential tremor: Epidemiology, diagnosis, and treatment. The Neurologist, 10(5):250–258.

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