Characterization of Whole-Body Vibration (WBV) exposure is important for the development and evaluation of mitigation strategies for occupational WBV. However, barriers associated with cost and ...complexity limit widespread use of current gold-standard accelerometer (GSA) measurement systems. Small, simple, low cost Acceleration Measurement Unit (AMU) devices with built-in batteries and memory potentially allow for more efficient collection of WBV data, but the measurement accuracy of these devices need to be evaluated. Using known acceleration inputs generated by an accelerometer calibrator and field collected vibration profiles simulating real-world vibration exposures, the measurements of an AMU device and GSA system were compared. Analysis of accelerometer calibrator data showed no significant difference in weighted acceleration (Aw) measurements between the systems (mean difference −0.001 m/s2, p = 0.95). In field collected vibration profile testing, differences in Aw measurements were small (0.06 m/s2, 4.6%). These results suggest the AMU evaluated in this study may be acceptable for measuring occupational WBV.
•Whole body vibration (WBV) is an occupational exposure common in drivers.•WBV is associated with low back pain and several other adverse health effects.•There are currently barriers to consistent measurement of WBV exposures.•We compared WBV measurements of an AMU device to current gold standard systems.•Results suggest an AMU device may be acceptable for measuring occupational WBV.
This study investigated the prediction of the discomfort caused by simultaneous noise and vibration from the discomfort caused by noise and the discomfort caused by vibration when they are presented ...separately. A total of 24 subjects used absolute magnitude estimation to report their discomfort caused by seven levels of noise (70-88 dBA SEL), 7 magnitudes of vibration (0.146-2.318 ms
− 1.75
) and all 49 possible combinations of these noise and vibration stimuli. Vibration did not significantly influence judgements of noise discomfort, but noise reduced vibration discomfort by an amount that increased with increasing noise level, consistent with a 'masking effect' of noise on judgements of vibration discomfort. A multiple linear regression model or a root-sums-of-squares model predicted the discomfort caused by combined noise and vibration, but the root-sums-of-squares model is more convenient and provided a more accurate prediction of the discomfort produced by combined noise and vibration.
Practitioner Summary: The total discomfort produced by combined noise and vibration, ψ
c
, can be well predicted from the root-sums-of-squares of the noise discomfort, ψ
s
, and the vibration discomfort, ψ
v
, when each stimulus is presented alone (i.e. ψ
c
= (ψ
v
)
2
+(ψ
s
)
2
0.5
).
Background: Work-related Musculoskeletal disorders (WRMSD) stand as a prevalent and significant occupational health issue within the teaching profession. Despite being overlooked for an extended ...period, there has been a growing level of concern about this issue in recent years. Objectives: 1. To estimate the prevalence of work-related musculoskeletal disorders among school teachers in Ernakulam district, Kerala. 2. To determine the risk factors associated with work-related musculoskeletal disorders. Methodology: A cross sectional study was conducted among 114 school teachers in Ernakulam district selected by multistage cluster sampling. A structured interview schedule was used to assess the sociodemographic and occupational characteristics. To investigate the musculoskeletal disorders, they were interviewed with the modified Nordic questionnaire. The data was entered in MS excel and analysis was done using SPSS version 21.0. Results: Mean age (SD) of the participants was 43.25 (7.56) years. The prevalence of Work-related Musculoskeletal disorders at any part of the body over the past 12 months among teachers was 52.6%. Knee pain (41.6%) was the most prevalent WRMSD followed by ankle (38.3%) pain. Commonly perceived risk factor was standing for prolonged periods (81.6%). Stair climbing was found to be the most difficult Activity of Daily Living affected due to the symptoms (55%). Calcium/Vitamin D supplements, intake of calcium rich diet and body mass index were significantly associated with WRMSD. Conclusion: The results highlighted the crucial need to follow ergonomic guidelines in order to reduce the strain on the musculoskeletal system experienced by teachers.
Objective:
We investigated how automation-induced human performance consequences depended on the degree of automation (DOA).
Background:
Function allocation between human and automation can be ...represented in terms of the stages and levels taxonomy proposed by Parasuraman, Sheridan, and Wickens. Higher DOAs are achieved both by later stages and higher levels within stages.
Method:
A meta-analysis based on data of 18 experiments examines the mediating effects of DOA on routine system performance, performance when the automation fails, workload, and situation awareness (SA). The effects of DOA on these measures are summarized by level of statistical significance.
Results:
We found (a) a clear automation benefit for routine system performance with increasing DOA, (b) a similar but weaker pattern for workload when automation functioned properly, and (c) a negative impact of higher DOA on failure system performance and SA. Most interesting was the finding that negative consequences of automation seem to be most likely when DOA moved across a critical boundary, which was identified between automation supporting information analysis and automation supporting action selection.
Conclusion:
Results support the proposed cost–benefit trade-off with regard to DOA. It seems that routine performance and workload on one hand, and the potential loss of SA and manual skills on the other hand, directly trade off and that appropriate function allocation can serve only one of the two aspects.
Application:
Findings contribute to the body of research on adequate function allocation by providing an overall picture through quantitatively combining data from a variety of studies across varying domains.
In recent years, the use of virtual prototyping has increased in product development processes, especially in the assessment of complex systems targeted at end-users. The purpose of this study was to ...evaluate the suitability of virtual prototyping to support human factors/ergonomics evaluation (HFE) during the design phase. Two different virtual prototypes were used: augmented reality (AR) and virtual environment (VE) prototypes of a maintenance platform of a rock crushing machine. Nineteen designers and other stakeholders were asked to assess the suitability of the prototype for HFE evaluation. Results indicate that the system model characteristics and user interface affect the experienced suitability. The VE system was valued as being more suitable to support the assessment of visibility, reach, and the use of tools than the AR system. The findings of this study can be used as a guidance for the implementing virtual prototypes in the product development process.
•Both AR and VE prototypes support the assessment of human factors/ergonomics during the design.•The VE system was more suitable to support the assessment of visibility, reach, and the use of tools than the AR system.•System model characteristics can impact the suitability of the virtual prototype for the HFE evaluation.•To assess HFE issues related to environment, force and time, more sensory modalities are required.
There is growing concern that surgeons are at increased risk for work-related orthopedic injuries due to poor ergonomics. We conducted a survey of North American cardiothoracic surgeons to evaluate ...the prevalence of occupational injury, as well as perceptions and use of ergonomic techniques.
Cardiothoracic surgeons identified through the Cardiothoracic Surgery Network were asked to complete a 33-question survey assessing their musculoskeletal health, as well as their perceptions and use of ergonomic techniques in the operating room and office.
Among 600 cardiothoracic surgeons, the prevalence of occupational musculoskeletal injuries was 64%, with 30% of affected surgeons requiring time away from work and 20% requiring surgery or the use of narcotics. Cervical spine injury (35%, n = 216) was the most common injury due to operating, followed by lumbar spine injury (30%, n = 180). In multivariable-adjusted analysis, cardiac surgeons were more likely than thoracic surgeons to experience occupational musculoskeletal injuries (adjusted odds ratio, 1.8 1.2-2.8, P < .01). Notably, 90% of surgeons (n = 536) reported thinking that their institution did not provide sufficient ergonomics education or support, and only 35% (n = 205) thought that the cardiothoracic surgical community is supportive of implementing ergonomics techniques in the operating room and office.
In this survey analysis, cardiothoracic surgeons reported experiencing work-related orthopedic injuries at an alarmingly high rate, leading to significant time away from work and for many to retire from surgery over a decade early. These findings underline a critical need for institutions to prioritize ergonomics education and implement ergonomics-directed techniques in the operating room and office.
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This research examines the status of human factors and ergonomics (HF/E) metrics in the case context of product realisation in an electronics manufacturing company. Interactions with 100+ ...stakeholders over a five year period were thematically analysed for metrics-related views and content. A disconnect between engineering metrics and HF/E metrics was evident. Engineers and HF/E specialists expressed different understandings of the gap between the disciplines and how to generate HF/E metrics that would fit the organisation. Other emerging themes provided insight for metrics development including improving indicator relatability, considerations for communication of information, and barriers to implementation of metrics. The results led to seven recommendations to help guide practitioners in developing and refining HF/E metrics as part of an organisation’s metrics system. This macroergonomic case study provides key points for consideration when developing HF/E focussed metrics to support organisations being more proactive with HF/E in work system design.
Practitioner summary: Metrics’ presence, stakeholder views on metrics, and metrics-related content in a case organisation were thematically analysed with a macroergonomics focus. Human factors and ergonomics metrics (HF/E) were disconnected from engineering metrics thus limiting the design team’s ability to handle human factors in design. Factors influencing HF/E metrics creation and integration were identified, resulting in seven recommendations for developing HF/E metrics.
This paper describes three applications of Rasmussen's idea to systems engineering practice. The first is the application of the abstraction hierarchy to engineering specifications, particularly ...requirements specification. The second is the use of Rasmussen's ideas in safety modeling and analysis to create a new, more powerful type of accident causation model that extends traditional models to better handle human-operated, software-intensive, sociotechnical systems. Because this new model has a formal, mathematical foundation built on systems theory (as was Rasmussen's original model), new modeling and analysis tools become possible. The third application is to engineering hazard analysis. Engineers have traditionally either omitted human from consideration in system hazard analysis or have treated them rather superficially, for example, that they behave randomly. Applying Rasmussen's model of human error to a powerful new hazard analysis technique allows human behavior to be included in engineering hazard analysis.
•System theory provides a formal foundation for much improved hazard analysis that includes humans as part of the system.•STAMP, a new model of causation built on Rasmussen's ideas, provides a way to understand accidents in sociotechnical systems.•Rasmussen's abstraction hierarchy underlies Intent Specifications, which ground specifications on psychological principles.•Rasmussen's model of human-task mismatch can be used to extend engineering hazard analysis to include human error.
In augmented reality (AR) environments, information is often distributed between real world and virtual contexts, and often appears at different distances from the user. Therefore, to integrate the ...information, users must repeatedly switch context and refocus the eyes. To focus at different distances, the user's eyes must accommodate, which when done repeatedly can cause eyestrain and degrade task performance. An experiment was conducted that examined switching context and focal distance between a real and an AR environment, using a text-based visual search task and a monocular optical see-through AR display. Both context switching and focal distance switching resulted in significantly reduced performance. In addition, repeatedly performing the task caused visual fatigue to steadily increase. Performance was particularly poor for virtual text presented at optical infinity, and for target letters that participants tried to read before their eyes had completely accommodated to a new focal distance. The results show that context switching and focal distance switching are important AR user interface design issues.
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