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THE INTERNATIONAL JOURNAL OF MEDICAL ROBOTICS AND COMPUTER ASSISTED SURGERY
Int J Med Robotics Comput Assist Surg 2010; 6: 334 –342.
ORIGINAL ARTICLE
Published online 7 July 2010 in Wiley Online Library (wileyonlinelibrary.com) DOI: 10.1002/rcs.340
Estimation and filtering of physiological tremor
for real-time compensation in surgical robotics
applications
K. C. Veluvolu
1
*
W. T. Ang
2
1
School of Electronics Engineering,
College of IT Engineering, Kyungpook
National University, Daegu, South
Korea
2
School of Mechanical and Aerospace
Engineering, Robotics Research
Centre, Nanyang Technological
University, Singapore
*Correspondence to: K. C. Veluvolu,
School of Electronics Engineering,
College of IT Engineering,
Kyungpook National University,
Daegu, South Korea.
E-mail: veluvolu@ee.knu.ac.kr
Accepted: 30 May 2010
Abstract
Background Physiological tremor is the main cause of imprecision in
microsurgical procedures/robotics applications. Existing methods, such as
weighted-frequency Fourier linear combiner (WFLC), rely on estimating the
tremor under the assumption that it has a single dominant frequency. This
paper focuses on developing a new algorithm for accurate tremor filtering in
real time.
Methods A study conducted on several novice subjects and microsurgeons
showed the tremor to contain several dominant frequencies in a band, rather
than a single dominant frequency. Based on the tremor characteristics, a new
algorithm band-limited multiple Fourier linear combiner (BMFLC) has been
developed to estimate a band of signals with multiple dominant frequencies.
A separation procedure to separate the intended motion/drift from the tremor
portion is also discussed.
Results A simulation study was first conducted to validate the theoretical
development on recorded tremor data. The experimental set-up was designed
to study the real-time performance of the proposed algorithm. Tremor
sensing using accelerometers is also discussed, with the proposed algorithm.
Our experiments showed that the developed BMFLC algorithm had an
average tremor compensation of 64% compared to 43% for the WFLC
algorithm in real-time for one degree of freedom (1-DOF) cancellation of
tremor.
Conclusions The BMFLC algorithm can be applied for the three axes
separately and 3-DOF cancellation of tremor can be achieved. Further research
is required to deal with complex gestures involved during microsurgery.
Copyright 2010 John Wiley & Sons, Ltd.
Keywords tremor filtering; real-time compensation; computer-assisted surgery;
signal processing
Introduction
Physiological tremor leads to an intolerable imprecision of surgical proce-
dure, e.g. for vitroretinal surgery, which requires a positioning accuracy
of about 10 µm (1). In (2) it was shown that the tremor corrupts the
voluntary motion, causing an unwanted disturbance or noise. Tremor is
an involuntary human hand motion, can be approximated by a sinusoidal
Copyright 2010 John Wiley & Sons, Ltd.