Improvement in modelling of physiological tremor by inclusion of grip force in quaternion weighted Fourier linear combiner

Abstract

Physiological tremor is an involuntary oscillatory movement of body parts particularly exhibited in hands. The unintended vibrations due to tremor causes tip of the microsurgical tools to fluctuate unnecessarily causing unacceptable imprecisions in micro-surgeries. All the existing algorithms such as weighted Fourier Linear Combiner (wFLC), and its extensions, treat three x, y and z axes of tremor as three independent channels. However our correlation and coherence analysis showed that there is significant coupling between tremor channels. More importantly grip force by which a surgeon holds a surgical device also shows significant coupling with three tremor channels, which has never been investigated before. We first modelled the tremor in 3 dimensions (3-D) using quaternion algebra, and found 27% improvement which we have presented in our previous work. In this paper, we show modelling tremor in 4 dimensions by incorporating grip force and three tremor channels further exploits the cross-channel coupling information which is naturally inherent between force and xyz tremor channels. Using quaternion algebra we extract this coupling information to improve the tremor modelling performance. We show that estimation performance of tremor improves by 45% using 4-D model instead 3-D, yielding overall improvement of 65% from 1-D to 4-D.

A Quaternion Weighted Fourier Linear Combiner for Modeling Physiological Tremor

“…Section IV and V are our Discussions and Conclusions, respectively. Preliminary results of this work were reported in [26], [27].…”

Design of an Enhanced FLC-Based Controller for Selective Harmonic Compensation in Active Power Filters

“…The FLC has low computational cost and inherently zero phase error [20]. The FLC operates only for a stationary fundamental frequency.…”

“…The FLC and WFLC diagrams are shown in Figure 1. It is conventional to use the WFLC and the FLC together to simplify the tuning of both algorithms, designating the WFLC only to readjust the frequency [18][19][20][21][22][23][24].…”

“…To improve the frequency estimated by them, a combination of three WFLCs is used in the SDFLC in this paper, instead of just one as was done in previously works [18]. It is conventional to use the WFLC and the FLC together to simplify the tuning of both algorithms, designating the WFLC only to readjust the frequency [18][19][20][21][22][23][24].…”

Singular Spectrum Analysis (SSA) Based Tremor Supression In Micro-Surgery

“…Hand stability degrades with increasing age and hence, further escalates the situation. Fatigue, alcohol and caffeine consumption and many more factors escalates manual stability of microsurgeons even in the youthful age of the surgeons [4]. A well-recognized technique for noise suppression and cancellation called singular spectrum analysis (SSA) is used to overcome the limitations of other algorithms.…”