Link to the University of Pittsburgh Homepage
Link to the University Library System Homepage Link to the Contact Us Form

DEVELOPMENT AND EVALUATION OF AN ENHANCED WEIGHTED FREQUENCY FOURIER LINEAR COMBINER ALGORITHM USING BANDWIDTH INFORMATION IN JOYSTICK OPERATION

Nho, Wonchul (2006) DEVELOPMENT AND EVALUATION OF AN ENHANCED WEIGHTED FREQUENCY FOURIER LINEAR COMBINER ALGORITHM USING BANDWIDTH INFORMATION IN JOYSTICK OPERATION. Doctoral Dissertation, University of Pittsburgh. (Unpublished)

[img]
Preview
PDF
Primary Text

Download (1MB) | Preview

Abstract

Driving an electric powered wheelchair with a joystick is a complex task for the user who has a pathological tremor. Most powered wheelchairs use simple filtering algorithms to reduce the effects of tremor. These algorithms work well in most situations, but fall short in others. This study addresses the problems associated with pathological tremor associated with Cerebral Palsy (CP). The purpose of this study is to know more about the characteristics of CP tremor with time-frequency analysis and to improve joystick control with other advanced filtering algorithms.We used three estimated parameters, instantaneous frequency (IF), instantaneous bandwidth (IB), and instantaneous power (IP), from a time-frequency distribution (TFD), to characterize CP tremor and to tune a notch filter for canceling CP tremor noise from a joystick signal in an off-line experiment. From the off-line experiment, we showed that our CP tremor suppression system performed better with the information of IF, IB, and IP. We also conducted an on-line experiment in which we introduced two tremor suppression algorithms. One is Weighted-frequency Fourier Linear Combiner (WFLC), which estimates a tremor frequency and its weight, and the other is our modified WFLC, which adjusts a notch width with respect to the bandwidth of CP tremor additionally. We implemented both algorithms on the virtual wheelchair driving test along with a commonly used low-pass filter. We recruited ten subjects who have CP tremor and tested them in a virtual wheelchair driving environment. We observed that CP tremors in the joystick signal were suppressed greatly by the new filtering algorithms. We learned that the time-delay of a low-pass filter caused serious performance degradation of wheelchair driving and observed that most subjects performed better with new filtering methods than with a low-pass filter. Furthermore, since our modified WFLC algorithm was able to reduce more CP tremor noise than WFLC, we learned that it is important to consider the bandwidth information of CP tremor when designing a tremor suppression system.


Share

Citation/Export:
Social Networking:
Share |

Details

Item Type: University of Pittsburgh ETD
Status: Unpublished
Creators/Authors:
CreatorsEmailPitt UsernameORCID
Nho, Wonchulgaussians@yahoo.com
ETD Committee:
TitleMemberEmail AddressPitt UsernameORCID
Committee CoChairBrienza, Daviddbrienza@pitt,edu
Committee CoChairBoston, J. Robertboston@ee.pitt.eduBBN
Committee MemberLi, Ching-Chungccl@engr.pitt.eduCCL
Committee MemberLee, Heung-nohnlee@ee.pitt.edu
Committee MemberMickle, Marlin Hmickle@ee.pitt.eduMICKLE
Committee MemberCooper, Rory Arcooper@pitt.eduRCOOPER
Date: 2 June 2006
Date Type: Completion
Defense Date: 16 December 2005
Approval Date: 2 June 2006
Submission Date: 16 December 2005
Access Restriction: No restriction; Release the ETD for access worldwide immediately.
Institution: University of Pittsburgh
Schools and Programs: Swanson School of Engineering > Electrical Engineering
Degree: PhD - Doctor of Philosophy
Thesis Type: Doctoral Dissertation
Refereed: Yes
Uncontrolled Keywords: cerebral palsy adaptive filter; virtual driving; time-frequency
Other ID: http://etd.library.pitt.edu/ETD/available/etd-12162005-140751/, etd-12162005-140751
Date Deposited: 10 Nov 2011 20:11
Last Modified: 19 Dec 2016 14:38
URI: http://d-scholarship.pitt.edu/id/eprint/10395

Metrics

Monthly Views for the past 3 years

Plum Analytics


Actions (login required)

View Item View Item