Occupational Ergonomics - Volume 3, issue 4

Authors: Bhattacharya, Amit

Article Type: Editorial

DOI: 10.3233/OER-2003-3401

Citation: Occupational Ergonomics, vol. 3, no. 4, pp. i-i, 2003

Authors: Grönqvist, Raoul | Matz, Simon | Hirvonen, Mikko

Article Type: Research Article

Abstract: The variation in utilized and available friction over shoe-floor contact time was determined in the presence of high- and low-viscosity contaminants. The objectives were to improve the validity of slipperiness evaluations and to find better criteria for safe friction during heel strike. The utilized friction coefficients for six shoe types were determined during gait-trials with male participants. The available friction coefficients of these shoes were measured with a test rig simulating heel slipping. The experiments were performed on a stainless steel floor with concentrated glycerol ('oily' condition) and diluted glycerol (1:10 in water) as contaminants. It was hypothesized that any …single friction measurement criterion would be an insufficient predictor for safe gait with no slip or with slip recovery, not leading to a fall. The results showed that both transitional friction (time-intervals from zero to about 250 ms of heel contact) and steady state kinetic friction (time-intervals from about 250 ms to 450 ms) properties in the shoe and floor interface play an important role in slipperiness measurement and slip/fall risk assessment. The role of static friction in the risk assessment remained unclear. Show more

Keywords: slipperiness measurement, available friction, utilized and required friction, heel contact phase, slip/fall risk, walking safety

DOI: 10.3233/OER-2003-3402

Citation: Occupational Ergonomics, vol. 3, no. 4, pp. 197-208, 2003

Authors: Chiou, Sharon S. | Bhattacharya, Amit | Lai, Chwan-Fu | Succop, Paul A.

Article Type: Research Article

Abstract: The objective of this study was to investigate the kinetic and kinematic aspects of slips associated with gait on a slippery surface under various environmental and job-task risk factors. Forty healthy industrial workers (age: 40.3 ± 14.9 years) participated in the study. Using a strain gauge type force platform and a video-based motion analysis system, kinetic and kinematic measurements of the subjects' foot movements were obtained. Of all gait trials, there were 1558 slips (60.9%). Slips were likely to occur when subjects were negotiating a turning path and an oily surface. Greater anterior-posterior center of pressure (CP) excursion and maximum …required coefficient of friction (RCOF) were found for oily surfaces compared to dry surfaces. Subjects changed their gait patterns by shortening their stride length, slowing walking speed, and decreasing heel contact angle in the poorly lit and slippery environment. Significant correlations were found between slip occurrence and anterior-posterior CP excursion, mean RCOF, sliding distance and sliding velocity, but not the coefficient of friction (COF) of shoes. In addition to good housekeeping and proper selection of floor materials and safety shoes, slip and fall prevention should include proper workers' training in dealing with risk factors of slips and falls in the workplace. Show more

Keywords: slip, gait adaption, turning path, slip and fall prevention

DOI: 10.3233/OER-2003-3403

Citation: Occupational Ergonomics, vol. 3, no. 4, pp. 209-223, 2003

Authors: Chambers, April J. | Margerum, Sarah | Redfern, Mark S. | Cham, Rakié

Article Type: Research Article

Abstract: Slip and fall accidents are often listed among the leading generators of injuries. The goals of this study were to (1) describe the foot kinematics during unexpected slips, and (2) to compare the foot kinematics during gait in unexpected slippery environment and when warnings of slippery environments are provided. Five participants walked on dry and glycerol-contaminated floors, while varying the participant's a-priori knowledge of the floor's contaminant condition. Foot kinematics were recorded at 500 Hz from 5 Optotrak LEDs placed on the slipping foot. In unexpected slips, all participants slipped and fell, whereas under the warning conditions, all participants slipped …and recovered. Foot kinematics were affected by the warning conditions. More specifically, the heel's vertical velocity just prior to impact and foot-floor angle at heel contact decreased in alert/known slippery environments compared to unexpected slips. Slip distances and velocities were greater in unexpected slips. Finally, the impact of recovery attempts on the heel's kinematics were evident earlier in stance when participants knew or suspected the floor was slippery. Thus, the a-priori perception of slippery surfaces affects the foot kinematics and outcome of slipping. Show more

Keywords: slips, foot, kinematics, falls

DOI: 10.3233/OER-2003-3404

Citation: Occupational Ergonomics, vol. 3, no. 4, pp. 225-234, 2003

Authors: Pan, Christopher S. | Chiou, Sharon | Hendricks, Scott

Article Type: Research Article

Abstract: Voluntary body movement can import a perturbation to the postural stability/balance of a human body. Heavy manual material handling such as drywall lifting may increase this perturbation. The objective of this laboratory-based study was to quantify workers' postural stability while lifting drywall sheets through kinetic and kinematic analyses, and to identify the drywall lifting methods that caused the least perturbation on workers' balance. Sixty male construction workers participated in this study. A simulated drywall-lifting workstation was built and all subjects performed one of the four randomly assigned lifting methods. Kinetic and kinematic measurements were synchronized and collected using a piezoelectric …force platform and a five-camera motion analysis system. Both center-of-pressure (COP) and center-of-mass (COM) data were analyzed to assess workers' postural stability. Univariate analyses and principal component analyses (PCA) were used to analyze 13 COP-based and 21 COM-based variables. Results from the univariate analyses and PCA significantly indicated that the three horizontal lifting methods created less perturbation than the vertical lifting method. Based on the results of this study and prior studies, it is concluded that horizontal lifting with both hands on top of the drywall appears to be the best work practice to reduce manual drywall handling hazards associated with fall potential and overexertion injuries. Show more

Keywords: drywall, lifting, kinematics, kinetics, center-of-pressure, center-of-mass, construction

DOI: 10.3233/OER-2003-3405

Citation: Occupational Ergonomics, vol. 3, no. 4, pp. 235-249, 2003

Authors: Kincl, Laurel | Bhattacharya, Amit | Succop, Paul | Bagchee, Angshuman

Article Type: Research Article

Abstract: Maintenance of upright balance involves interplay between sensory (somatosensory, vestibular and visual) inputs and neuro-motor outputs. Visual spatial perception (VSP) of vertical and horizontal orientation plays a significant role in the maintenance of upright balance. For this experiment, a custom designed computer program randomly generated 42 images of horizontal and vertical lines at various angles for 60 industrial workers (39 ± 9.8 years). Half of the workers had more than three years of experience working on inclined and/or elevated surfaces. The main effects investigated included within subject factors of standing surface inclination (0°, 14° and 26°), job experience (number of …months), and postural workload (0%, 50% or 100%). The VSP outcome measure was the count of correct responses to the angles presented. The inclination did not have a significant effect on VSP, but the parameter estimates indicated less correct responses on the inclined surfaces. The postural workload significantly affected the VSP, indicating that with increased workload, less correct responses were given. Finally, job experience was found to improve VSP response scores. In summary, these results indicate that job experience increases accurate VSP, while workloads and inclined work surfaces decrease accurate VSP responses. Show more

Keywords: visual spatial perception, postural balance, postural workload, work experience, occupational falls

DOI: 10.3233/OER-2003-3406

Citation: Occupational Ergonomics, vol. 3, no. 4, pp. 251-259, 2003