Ergonomics

ObjectiveA new equation for predicting the hand activity level (HAL) used in the ACGIH threshold limit value\uc2\uae (TLV\uc2\uae), was based on exertion frequency (F) and percentage duty cycle (D).BackgroundThe TLV\uc2\uae includes a table for estimating HAL from F and D originating from data in Latko et al. (1997) and post-hoc adjustments that includes extrapolations outside of the data range.MethodsMultimedia video task analysis determined D for two additional jobs from Latko\ue2\u20ac\u2122s study not in the original data set, and a new non-linear regression equation was developed to better fit the data and create a more accurate table.ResultsThe equation, HAL=6.56lnD[F1.311+3.18F1.31], generally matches the TLV\uc2\uae HAL lookup table, and is a substantial improvement over the linear model, particularly for F > 1.25 Hz and D > 60% jobs.ConclusionThe equation more closely fits the data and applies the TLV\uc2\uae using a continuous function.Practitioner SummaryThe original HAL lookup table is limited in resolution, omits values, and extrapolates values outside of the range of data. A new equation and table was developed to address these issues.R01OH007914/OH/NIOSH CDC HHS/United StatesR21OH010221/OH/NIOSH CDC HHS/United StatesUL1 TR000427/TR/NCATS NIH HHS/United States2015-02-01T00:00:00Z25343340PMC430273

Int J Ind Ergon

Relevance to industryExposure to hazardous levels of repetitive action during non-cyclic task completion has traditionally been difficult to assess using simple observational techniques. The present study suggests that ergonomists could use the HAL to reliably and easily evaluate exposures associated with some non-cyclic work tasks.R01 OH007945/OH/NIOSH CDC HHS/United StatesT42 OH009229/OH/NIOSH CDC HHS/United States2015-06-24T00:00:00Z26120222PMC448021

Development, application, and reliability of methods for ergonomic workload assessments in production evaluation and workstation design

Ergonomics assessments of conditions for humans at workstations and in manufacturing processes are necessary to prevent work-related musculoskeletal disorders and enhance efficiency and quality. Many methods can be used for this from systematic observations to direct measurements and simulation. Investigations of the accuracy and reliability of many methods as well as comparisons between them have been performed, but there is still need for further work as well as development of new methods.The inter- and intra-rater reliability of the OCRA checklist was studied through eleven ergonomists’ risk-assessments of ten video-recorded work tasks on two occasions. The statistical analysis included several parameters of reliability of which Cohen\u27s linearly weighted kappa was the primary measure. The inter-rater agreement of the OCRA checklist was 39%, and the weighted kappa was 0.43; the intra-rater dittos were 45% and 0.52. This indicated that the OCRA checklist is a moderately reliable tool.A risk assessment approach for digital human modelling (DHM) was developed. The approach included a reference database of epidemiological relationships between directly measured exposure and related musculoskeletal disorders. For illustration, a case in manual assembly was simulated; exposures were calculated and compared to the reference data to indicate the risk of WMSDs. The application and detailed assessment would be helpful to prioritise among different design solutions.A 3D digital prototype laparoscopic robotic console was ergonomically evaluated using the DHM tool IMMA with 12 manikins representing anthropometries of the Swedish and US population. Work-ranges of the console and the manikins were calculated, compared and ergonomically assessed using the Swedish standards and a US checklist for computer work. The assessment criteria related to the adjustable ranges of the screen height, height of the armrest, adjustable range of the pedals were not fulfilled. The DHM tool IMMA provides the possibility for a pre-production assessment of static work tasks