An analytical method for characterizing repetitive motion and postural stress using spectral analysis.
Ergonomics 1993 Apr; 36(4):379-389
The ability of spectral analysis of electrogoniometric data to characterize repetitive wrist motions and postural stress in cyclical tasks was examined. Subjects instrumented with electrogoniometers attached to the dorsum of the wrist of the dominant arm performed a simple peg transfer task utilizing two peg boards. The wrist posture was controlled and forced into a neutral position by adjusting the pegboard locations and having the subjects reach over a horizontal bar placed in front of the upper peg board. The work pace was controlled by an auditory signal from an electronic timer. Wrist flexion or extension angles and ulnar or radial deviations of the wrist from the neutral posture were recorded by the electrogoniometer using a 60 hertz sampling rate. Power spectra were computed from the data by decomposing each task into appropriate segments which were divided by the task elements, defined as a set of movements contained between two arbitrary, distinct breakpoints for each task, utilizing a Fourier transform technique. Attempts were made to correlate the direct current (DC) and alternating current (AC) components of the spectra with wrist posture and joint displacement amplitudes and frequency rates. The DC components were directly related to the sustained wrist postures independently of the AC components. The AC components were significantly associated with displacement amplitudes and repetition rates independently of the DC components. The authors conclude that power spectrum DC components can measure sustained postures and AC components repetitive movements independently of each other. Power spectral analysis can be used for analyzing repetitive motions in cyclic tasks and their relationship to cumulative trauma disorders.
NIOSH-Publication; NIOSH-Grant; Musculoskeletal-system-disorders; Task-performance; Electrophysiological-measurements; Work-analysis; Repetitive-work; Cumulative-trauma-disorders; Ergonomics; Laboratory-testing
Industrial Engineering Univ of Wisconsin-Madison 1513 University Ave Madison, WI 53706
University of Wisconsin Madison, Madison, Wisconsin