Field studies using spectral analysis for quantifying upper extremity repetitive motion.
Second International Scientific Conference on Prevention of Work-Related Musculoskeletal Disorders, Montreal 1995 Sep:274-276
A study was conducted comparing operator movements between two vehicles for an earth moving task. Electrogoniometers continuously measured upper extremity movements, and spectral analysis was used to quantify motion for specific upper extremity joints associated with each cab. Three experienced male operators operated two wheel loaders, identical other than cab controls. One vehicle had a conventional steering wheel and transmission lever for forward/reverse and gear shifting. The other vehicle had a laterally tilting control stick for steering, and finger triggers for forward/reverse and for gear shifting. Representation spectra for elbow flexion/extension when using the conventional steering wheel and the stick steering control were presented. Mean joint RMS motion, repetition frequency, and sustained posture for six upper extremity joints were provided. Spectra for the steering wheel contained greater magnitudes and frequencies than for the stick control. No significant difference in mean cycle times was noted between the two vehicles. Mean cycle time was 15.7 seconds for the steering wheel and 15.9 seconds for the stick. Wrist flexion/extension frequency was 40% greater for the wheel than for the stick. Elbow RMS flexion was 150% less and repetition frequency was 57% less for the stick than for the steering wheel. Repetition frequency increased 37% for the stick. The findings demonstrated that specific aspects of physical stress exposure from repetitive movements can be quantified and improvements in job design for a specific task can be made objectively and analytically monitored. The authors suggest that methods such as spectral analysis will allow investigators to study operator exposure over longer periods and provide more accurate and precise data using continuous biomechanical measurements.
NIOSH-Grant; Musculoskeletal-system-disorders; Muscle-function; Repetitive-work; Task-performance; Ergonomics; Construction-equipment; Posture; Human-factors-engineering; Equipment-operators
Industrial Engineering Univ of Wisconsin-Madison 1513 University Ave Madison, WI 53706
Second International Scientific Conference on Prevention of Work-Related Musculoskeletal Disorders, Montreal
University of Wisconsin Madison, Madison, Wisconsin