The University of Southampton
University of Southampton Institutional Repository

The effects of whole-body vibration on performance of a complex manual control task

The effects of whole-body vibration on performance of a complex manual control task
The effects of whole-body vibration on performance of a complex manual control task
This thesis investigates continous manual control performance during exposure to z-axis whole-body vibration at frequencies between 0.5 and 10.0 Hz. The task involved first-order pursuit tracking with a simultaneous discrete target acquisition task. A major aim of the work was to determine the mechanisms underlying any vibration-induced impairment which occurred. The iterature is first reviewed (Chapter 2) and a model is presented summarising the mechanisms by which vibration has been suggested to disrupt performance (Chapter 3). Six experiments are then reported. Experiment 1 (Chapter 5) measured vibration-induced activity at the head, hand and the output of the system dynamics. The results are discussed with reference to the mechanisms which could disrupt performance. Experiment 2 (Chapter 6) investigated performance during exposure to vibration at frequencies from 0.5 to 5.0 Hz. The magnitude of performance disruption was approximately constant at vibration frequencies below 2 Hz, and increased with the frequency of vibration to 5.0 Hz. Experiments 3 (Chapter 7) and 4 (Chapter 8) showed that the disruption at frequencies above 2.0 Hz could be attributed to visual impairment arising from relative translational movement between subjects' eyes and the display: collimating the display removed the impairment. Linear spectral analysis techniques were used to separate root-mean-square (rms) tracking error into components linearly and not linearly correlated with movements of the target. Changes in total rms error were mainly accompanied by changes in the linear components: closed-loop system transfer functions showed increased phase lags between movements of the target and the response of the controlled element. In experiment 5 (Chapter 9), three simple tasks were used to isolate non-visual mechanisms of disruption. The results suggested that whole-body vibration at 0.5 and 4.0 Hz could interfere with neuro-muscular processes. The results of experiment 5, and the increased phase lag observed in experiment 4, indicate changes in the way the task was performed during vibration: these are described as secondary vibration effects. Experiment 6 investigated whether the effect of vibration on the system studied would be time-dependent. One-octave-band random vibration centred on 4 Hz was presented at a magnitude considerably above the ISO 2631 (1985) `fatigue-decreased-proficiency' limit for 180 minute vibration exposures. Performance declined with time, but vibration did not alter the time-dependence. The effect of duration was reduced when the task was performed over the entire duration on a second occasion. It is concluded that impairments in continuous tracking performance during whole-body vibration exposure were mainly caused by interference with visual and neuro-muscular processes. The results also show secondary effects which may represent adaptive change in performance during vibration. The behavioural model developed in Chapter 3 is used to summarise the mechanisms which were shown to be important, and to indicate other effects which could occur. Some suggstions for further research are offered.
McLeod, R.W.
a8936cb6-07b8-4353-8116-68ab0637e6a2
McLeod, R.W.
a8936cb6-07b8-4353-8116-68ab0637e6a2
Griffin, Michael
24112494-9774-40cb-91b7-5b4afe3c41b8

McLeod, R.W. (1986) The effects of whole-body vibration on performance of a complex manual control task. University of Southampton, Institute of Sound and Vibration Research, Doctoral Thesis.

Record type: Thesis (Doctoral)

Abstract

This thesis investigates continous manual control performance during exposure to z-axis whole-body vibration at frequencies between 0.5 and 10.0 Hz. The task involved first-order pursuit tracking with a simultaneous discrete target acquisition task. A major aim of the work was to determine the mechanisms underlying any vibration-induced impairment which occurred. The iterature is first reviewed (Chapter 2) and a model is presented summarising the mechanisms by which vibration has been suggested to disrupt performance (Chapter 3). Six experiments are then reported. Experiment 1 (Chapter 5) measured vibration-induced activity at the head, hand and the output of the system dynamics. The results are discussed with reference to the mechanisms which could disrupt performance. Experiment 2 (Chapter 6) investigated performance during exposure to vibration at frequencies from 0.5 to 5.0 Hz. The magnitude of performance disruption was approximately constant at vibration frequencies below 2 Hz, and increased with the frequency of vibration to 5.0 Hz. Experiments 3 (Chapter 7) and 4 (Chapter 8) showed that the disruption at frequencies above 2.0 Hz could be attributed to visual impairment arising from relative translational movement between subjects' eyes and the display: collimating the display removed the impairment. Linear spectral analysis techniques were used to separate root-mean-square (rms) tracking error into components linearly and not linearly correlated with movements of the target. Changes in total rms error were mainly accompanied by changes in the linear components: closed-loop system transfer functions showed increased phase lags between movements of the target and the response of the controlled element. In experiment 5 (Chapter 9), three simple tasks were used to isolate non-visual mechanisms of disruption. The results suggested that whole-body vibration at 0.5 and 4.0 Hz could interfere with neuro-muscular processes. The results of experiment 5, and the increased phase lag observed in experiment 4, indicate changes in the way the task was performed during vibration: these are described as secondary vibration effects. Experiment 6 investigated whether the effect of vibration on the system studied would be time-dependent. One-octave-band random vibration centred on 4 Hz was presented at a magnitude considerably above the ISO 2631 (1985) `fatigue-decreased-proficiency' limit for 180 minute vibration exposures. Performance declined with time, but vibration did not alter the time-dependence. The effect of duration was reduced when the task was performed over the entire duration on a second occasion. It is concluded that impairments in continuous tracking performance during whole-body vibration exposure were mainly caused by interference with visual and neuro-muscular processes. The results also show secondary effects which may represent adaptive change in performance during vibration. The behavioural model developed in Chapter 3 is used to summarise the mechanisms which were shown to be important, and to indicate other effects which could occur. Some suggstions for further research are offered.

Other
000801.PDF - Other
Download (15MB)

More information

Published date: 1986
Organisations: University of Southampton

Identifiers

Local EPrints ID: 52294
URI: https://eprints.soton.ac.uk/id/eprint/52294
PURE UUID: da19cc6b-f625-459b-8a73-fcb3822ea3ff
ORCID for Michael Griffin: ORCID iD orcid.org/0000-0003-0743-9502

Catalogue record

Date deposited: 26 Aug 2008
Last modified: 14 Mar 2019 01:56

Export record

Download statistics

Downloads from ePrints over the past year. Other digital versions may also be available to download e.g. from the publisher's website.

View more statistics

Atom RSS 1.0 RSS 2.0

Contact ePrints Soton: eprints@soton.ac.uk

ePrints Soton supports OAI 2.0 with a base URL of https://eprints.soton.ac.uk/cgi/oai2

This repository has been built using EPrints software, developed at the University of Southampton, but available to everyone to use.

We use cookies to ensure that we give you the best experience on our website. If you continue without changing your settings, we will assume that you are happy to receive cookies on the University of Southampton website.

×