Effects of sensor types and angular velocity computational methods in field measurements of occupational upper arm and trunk postures and movements

Accelerometer-based inclinometers have dominated kinematic measurements in previous field studies, while the use of inertial measurement units that additionally include gyroscopes is rapidly increasing. Recent laboratory studies suggest that these two sensor types and the two commonly used angular velocity computational methods may produce substantially different results. The aim of this study was, therefore, to evaluate the effects of sensor types and angular velocity computational methods on the measures of work postures and movements in a real occupational setting. Half-workday recordings of arm and trunk postures, and movements from 38 warehouse workers were compared using two sensor types: accelerometers versus accelerometers with gyroscopes—and using two angular velocity computational methods, i.e., inclination velocity versus generalized velocity. The results showed an overall small difference (<2\ub0 and value independent) for posture percentiles between the two sensor types, but substantial differences in movement percentiles both between the sensor types and between the angular computational methods. For example, the group mean of the 50th percentiles were for accelerometers: 71\ub0/s (generalized velocity) and 33\ub0/s (inclination velocity)—and for accelerometers with gyroscopes: 31\ub0/s (generalized velocity) and 16\ub0/s (inclination velocity). The significant effects of sensor types and angular computational methods on angular velocity measures in field work are important in inter-study comparisons and in comparisons to recommended threshold limit values

Mind the gap – development of conversion models between accelerometer- and IMU-based measurements of arm and trunk postures and movements in warehouse work

Sensor type (accelerometers only versus inertial measurement units, IMUs) and angular velocity computational method (inclination versus generalized velocity) have been shown to affect the measurements of arm and trunk movements. This study developed models for conversions between accelerometer and IMU measurements of arm and trunk inclination and between accelerometer and IMU measurements of inclination and generalized (arm) velocities. Full-workday recordings from accelerometers and IMUs of arm and trunk postures and movements from 38 warehouse workers were used to develop 4 angular (posture) and 24 angular velocity (movement) conversion models for the distributions of the data. A power function with one coefficient and one exponent was used, and it correlated well (r2 > 0.999) in all cases to the average curves comparing one measurement with another. These conversion models facilitate the comparison and merging of measurements of arm and trunk movements collected using the two sensor types and the two computational methods

A possible revival of population-representing digital human manikins in static work situations - exemplified through an evaluation of a prototype console for robotic surgery

BACKGROUND: In the 90s, digital human manikins (DHMs) were introduced in planning ofworkstations, by static or semi-static simulations. Modern DHMs can simulate dynamic work and offer a rapid way for a virtual pre-production ergonomic evaluation. Work-related musculoskeletal disorders may affect surgical performance and patient safety. A prototype of an open console, which is contrary to the conventional closed consoles and may be seen as a representative for a new generation, has been designed to reduce workload for robotic surgery surgeons. OBJECTIVE: The aim of this project was to test a new DHM tool with improved usability to evaluate the ergonomics of a console of a robotic surgical system in a pre-production stage. METHODS: The DHM tool IMMA was used together with a 3D model of the prototype console. Twelve manikins who represented females and males from two national populations were introduced. Manikin-console distances, after console adjustments per manikin, were compared with a US checklist and Swedish standard for VDU work. RESULTS: The DHM tool was useful for this case, but the distances of the checklist and the standard were needed to be obtained "manually". The automatic functions of the DHM worked smoothly but were not optimized for VDU work. The prototype fulfilled most, but not all, of the ergonomic criteria of the checklist and the standard. CONCLUSIONS: There is room for improvements of the adjustable ranges of the console prototype. DHMs may facilitate rapid pre-production evaluation of workstations for static work; if ergonomic assessment models for VDU work are built-in, there may be a revival of DHMs in static work situations

Sleep-Related Problems and Associations with Occupational Factors among Home Care Personnel

Recent demographic developments in Europe have increased the demand for home care. Working in other people’s home environment is challenging. Home care personnel’s musculoskeletal disorders are common, and care personnel overall often have sleep disturbances. In this study, associations between occupational physical and psychosocial factors and possible sleep-related problems among home care personnel were explored using a questionnaire. The questionnaire was distributed to 19 workplaces in Stockholm County in 2017–2019, and 665 home care personnel answered. Several factors, including job contentment, physical burden of care, client-related burnout, quantitative demands, and pain, were significantly associated with sleep-related problems. The results highlight the need for implementing measures to improve psychosocial and organizational working conditions in home care service

Sleepiness and stress among long-haul truck drivers : An educational intervention to promote safe and economic truck driving

Sleepiness and stress at the wheel are known to be common among professional drivers. Given the safety-sensitive nature of the job, it would be essential for neither of these conditions to reach levels compromising safe driving. The current field study examined the levels of sleepiness and stress at the wheel in a group of Finnish long-haul truck drivers, and the potential factors contributing to the sub-optimal levels of arousal. Over and above, the study examined whether driver alertness could be amended by short one-time alertness management training. The results revealed that driver sleepiness reaches potentially risky levels, especially during the first night shift in the beginning of a shift spell. No clear evidence was found to support the idea that educating professional drivers on alertness management would be sufficient for mitigating their sleepiness on the road

Interaction of climate change with effects of conspecific and heterospecific density on reproduction

We studied the relationship between temperature and the coexistence of great titParus majorand blue titCyanistes caeruleus, breeding in 75 study plots across Europe and North Africa. We expected an advance in laying date and a reduction in clutch size during warmer springs as a general response to climate warming and a delay in laying date and a reduction in clutch size during warmer winters due to density-dependent effects. As expected, as spring temperature increases laying date advances and as winter temperature increases clutch size is reduced in both species. Density of great tit affected the relationship between winter temperature and laying date in great and blue tit. Specifically, as density of great tit increased and temperature in winter increased both species started to reproduce later. Density of blue tit affected the relationship between spring temperature and blue and great tit laying date. Thus, both species start to reproduce earlier with increasing spring temperature as density of blue tit increases, which was not an expected outcome, since we expected that increasing spring temperature should advance laying date, while increasing density should delay it cancelling each other out. Climate warming and its interaction with density affects clutch size of great tits but not of blue tits. As predicted, great tit clutch size is reduced more with density of blue tits as temperature in winter increases. The relationship between spring temperature and density on clutch size of great tits depends on whether the increase is in density of great tit or blue tit. Therefore, an increase in temperature negatively affected the coexistence of blue and great tits differently in both species. Thus, blue tit clutch size was unaffected by the interaction effect of density with temperature, while great tit clutch size was affected in multiple ways by these interactions terms.Peer reviewe