Inertia Artefacts and Their Effect on the Parameterisation of Keyboard Reaction Forces

Details

• Personal Author:
  Asundi K ; Dennerlein, Jack T. ; Johnson PW
• Description:
  Reaction force measurements collected during typing on keyboard trays contain inertia artefacts due to dynamic movements of the supporting work surface. To evaluate the effect of these artefacts, vertical forces and accelerations were measured while nine volunteers touch-typed on a rigid desk and a compliant keyboard tray. Two signal processing methods were evaluated: 1) low pass filtering with 20 Hz cut-off; 2) inertial force cancellation by subtracting the accelerometer signal. High frequency artefacts in the force signal, present on both surfaces, were eliminated by low pass filtering. Low frequency artefacts, present only when subjects typed on the keyboard tray, were attenuated by subtracting the accelerometer signal. Attenuation of these artefacts altered the descriptive statistics of the force signal by as much as 7%. For field measurements of typing force, reduction of low frequency artefacts should be considered for making more accurate comparisons across groups using work surfaces with different compliances. Direct measures of physical risk factors in the workplace can improve understanding of the aetiology of musculoskeletal disorders. Findings from this study characterise inertia artefacts in typing force measures and provide a method for eliminating them. These artefacts can add variability to measures, masking possible differences between subject groups. [Description provided by NIOSH]
• Subjects:
  Biomechanical Phenomena Computers Ergonomics Laboratories Musculoskeletal System Occupational Exposure Occupational Health Safety Software Workplace
• Keywords:
  Author Keywords: Exposure Assessment Tools Biomechanics Computer-equipment Computer-software Keyboard-operators Laboratory-testing Measurement-equipment Muscles Musculoskeletal-system Occupational-exposure Physical Risk Factors Posture Standards Statistical-analysis Work-areas Work-practices Work-related Musculoskeletal Disorders Workplace-studies

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• ISSN:
  0014-0139
• Document Type:
  Text
• Funding:
  Grant
• Genre:
  Journal Article
• Place as Subject:
  Massachusetts ; OSHA Region 1
• CIO:
  National Institute for Occupational Safety and Health (NIOSH)
• Topic:
  Workplace Safety & Health
• Location:
  North America
• Volume:
  52
• Issue:
  10
• NIOSHTIC Number:
  nn:20035949
• Citation:
  Ergonomics 2009 Oct; 52(10):1259-1264
• Contact Point Address:
  Department of Environmental Health, Harvard School of Public Health, Boston, MA 02115
• Federal Fiscal Year:
  2010
• Performing Organization:
  Harvard University, Boston, Massachusetts
• Peer Reviewed:
  True
• Start Date:
  19990930
• Source Full Name:
  Ergonomics
• End Date:
  20090831
• Collection(s):
  National Institute for Occupational Safety and Health
• Main Document Checksum:
  urn:sha-512:65d68acde863ab48f33fc33ef8f7805fba8efd76098421c04826486e7a47c4ff58836df6f773652c024d36ceb0d3453e3066fc6e3446581690ee43154d5c3a30
• Download URL:
  https://stacks.cdc.gov/view/cdc/187598/cdc_187598_DS1.pdf
• File Type:
  [PDF - 455.50 KB ]