Optimal digital filtering for tremor suppression.
Remote manually operated tasks such as those found in teleoperation, virtual reality, or joystick-based computer access, require the generation of an intermediate electrical signal which is transmitted to the controlled subsystem (robot arm, virtual environment, or a cursor in a computer screen). When human movements are distorted, for instance, by tremor, performance can be improved by digitally filtering the intermediate signal before it reaches the controlled device. This paper introduces a novel tremor filtering framework in which digital equalizers are optimally designed through pursuit tracking task experiments. Due to inherent properties of the man-machine system, the design of tremor suppression equalizers presents two serious problems: 1) performance criteria leading to optimizations that minimize mean-squared error are not efficient for tremor elimination and 2) movement signals show ill-conditioned autocorrelation matrices, which often result in useless or unstable solutions. To address these problems, a new performance indicator in the context of tremor is introduced, and the optimal equalizer according to this new criterion is developed. Ill-conditioning of the autocorrelation matrix is overcome using a novel method which we call pulled-optimization. Experiments performed with artificially induced vibrations and a subject with Parkinson's disease show significant improvement in performance. Additional results, along with MATLAB source code of the algorithms, and a customizable demo for PC joysticks, are available on the Internet at http:¿tremor-suppression.com.
Gonzalez
J G
JG
Department of Electrical and Computer Engineering, University of Delaware, Newark 19716, USA.
Heredia
E A
EA
Rahman
T
T
Barner
K E
KE
Arce
G R
GR
D000465:Algorithms; D016287:Computer Peripherals; D004867:Equipment Design; D006801:Humans; D010300:Parkinson Disease / Q000150:complications / Q000503:physiopathology*; D012371:Robotics; D012815:Signal Processing, Computer-Assisted; D014202:Tremor / Q000209:etiology / Q000503:physiopathology*; D014732:Vibration