International Journal of Industrial Ergonomics最新文献

As exoskeletons and exosuits rapidly transition from laboratory to practice, the thermal discomfort posed by wearing the devices is emerging as a significant challenge towards their widespread adoption. We use a thermal manikin coupled with a thermoregulation model to evaluate the thermal properties and thermophysiological impacts of such devices. We measure thermal and evaporative resistances of summer and full clothing coupled with a legacy low-back supporting exosuit and its successor that features two design alterations to improve the user's thermal comfort. We quantify the decrease in evaporative resistance provided by substantial perforation of the back portion of the updated exosuit. The thermal manikin can replicate local skin temperature decrease associated with a release of a dual-mode thigh body attachment measured during a prior human trial. Using the thermal manikin coupled with a thermoregulation model, we simulate how the updated exosuit with several levels of assumed metabolic rate reduction impacts sweat rate, skin and core temperature changes during multiple work-rest cycles in a hot and humid climate. While a large metabolic rate reduction (>15%) is required to significantly slow the core temperature increase, even a minor metabolic rate reduction (5%) could provide a substantial reduction (20%) in the sweat rate (i.e. could reduce dehydration). Results suggest that thermal manikins with a thermoregulation model are an effective and efficient platform for comparing exosuit design features and for improving their thermal aspects. Our study highlights the comprehensive method and importance of considering thermal aspects when designing exosuits for occupational use.

To improve the comfort of seat support performance, we proposed a seat dimensions design method. First, an adjustable seat was used to obtain the measurement data of user-selected comfortable seat dimensions. Second, the differences in the measurement data of different body types and riding time variables were analyzed. Third, a compromise treatment method for the different comfort requirements was developed. This method was applied to the design of passenger seats for short-distance flights in China. The lumbar support thickness was significantly different in the time variables, and the seat pan inclination and neck support height were significantly different among body types. We did not find significant differences, however, in seat height, backrest inclination, lumbar support height, or neck support thickness according to time or body type variables. There is one optimal dimension for seat height (430.5 mm), backrest inclination (104.2°), lumbar support height (98.8 mm), and neck support thickness (44.4 mm). However, seat pan inclination (5.8°, 7.2°, and 9.3°), neck support height (582.6 mm and 622.5 mm), and lumbar support thickness (40.6 mm and 48.7 mm) need multiple dimensions to meet passenger comfort requirements. This seat dimension design method provides new ideas to explore the comfort requirements of passengers and addresses the differences in comfortable seat dimension requirements for different body types and different flight durations.

Aim

To identify the presence of spinal pain and compare spine curvatures, mobility, and competency according to spine region in dentists working in risky postures.

Methods

One hundred twenty-two dentists aged between 18 and 40 years (52 males, 70 females; age: 25.94 ± 3.40 years), who at least in a medium risk group according to the Rapid Entire-Body Assessment (REBA) were included. The Extended Nordic Musculoskeletal Questionnaire for pain and skin-surface Valedo®Shape device (Idiag, Fehraltorf, Switzerland) for spinal curvature, inclination from the center of gravity, mobility, and postural competency were used.

Results

The REBA risk classification was medium (36.1%), high (56.6%), and very high (7.4%). The spinal pain rate in at least one region was 79.5%, and in all regions was 34.4%. The pain was in the neck (62.3%), mid-back (60.7%), and low back (53.3%) with the following intensities 4.00 ± 1.64, 4.05 ± 1.89, and 4.09 ± 2.11, respectively. In the sagittal plane, inclination in mobility decreased in the low back pain group (p = 0.045). In the frontal plane, the thoracic curvature angle increased (p = 0.023), and inclination in mobility decreased (p = 0.044) in the mid-back pain group, and postural competency differences in sacral region in the low back pain group were observed (p = 0.037). Dentists experiencing both mid and low back pain showed increased thoracic curvature angle (p = 0.020) and differences in sacral competency (p = 0.044) in the frontal plane.

Conclusion

The regional spinal pain rate with moderate intensity was about 80% in dentists working in risky postures. The mobility and postural competency changes with thoracic curvature increase were observed in dentists who had pain in the mid-back and low back regions.

The complexity and diversity of products significantly increases the difficulty of training workers in modern industries. AR training, as a combination of industrial digital development and new interactive means, has attracted increasingly more attention. However, in human factor and education, research regarding AR based training is still in its infancy. To understand how AR could help industrial training from a human perspective, we evaluate a HoloLens-based AR training method for an assembly task on natural human behavior and the training effectiveness. Forty-four participants were equally divided into AR and ordinary training groups with the equivalent instructional materials, which included text information and 3D models. Results show that although AR did not significantly affect the overall workload and system usability assessment (SUS) recorded, several experimental values increased significantly compared with the ordinary training method, including task completion time, time required to interpret text-based information, amount of attention switching, and training effectiveness. Consequently, the use of AR did not result in a completion time and workload reduction; however, we found that training with the AR system was more effective than ordinary training in increasing the knowledge retention of participants without increasing their overall workload, especially for the month-term memory. Nonetheless, a longer time was required by the users to familiarize themselves with the AR environment and read the text information. The findings of this work could contribute to the design of future AR training systems in industry considering natural human behavior and enhance training effectiveness.

An effective method for educating workers about occupational hazards is the use of safety signs in the workplace. However, workers' understanding may vary due to factors such as cultural background, familiarity, and training. This study aimed to assess the comprehension of international safety signs among participants representing the prospective technical workforce in Indonesian industries. Two groups of participants (n = 71), comprising vocational high school students and college-level engineering students, were involved to assess their comprehension of symbol elements, comprehension of complete signs, compliance intention, and familiarity towards a selected set of international safety signs. The study revealed that the complete signs significantly increased the comprehension and compliance intention of the prospective technical workers regarding the selected signs (p < .001). However, most safety signs under the fire equipment and safe condition categories investigated in the study had low comprehension and compliance intention scores (<67%). Conversely, signs under the mandatory and warning categories generally exhibited better comprehension and compliance intention scores. Additionally, participants in the study were generally not familiar with the investigated signs (<50%). The familiarity with the signs was strongly correlated with the comprehension and compliance intention of the participants (p < .001).

Relevance to industry

Understanding the findings, which revealed that the comprehension, compliance intention, and familiarity of the prospective technical worker participants with some international safety signs generally did not meet the standards, interventions such as training and redesigning the safety signs are highly recommended to minimize future adverse safety outcomes when they enter the workforce.

Stairs are one of the most dangerous places for accidental falls in both daily life and occupational settings. Knowledge about ground reaction force (GRF) characteristics during stair negotiation can facilitate a better understanding of the causal mechanisms for stair falls. The objective of this study was to investigate the effects of mobile phone texting on GRF during stair negotiation and reveal their implications associated with the safety during stair negotiation. Twelve young male adults were involved in an experimental study. They were instructed to carry out texting tasks with different levels of cognitive load while performing stair negotiation. Vertical GRF (vGRF) parameters accounting for force amplitude and loading/unloading rates were compared between texting conditions. Texting tasks resulted in slower force loading and unloading rates during stair ascent, while weight acceptance force during stair descent decreased with the application of texting tasks. These findings suggested that mobile phone texting can compromise postural stability and increase the risk of falls during stair negotiation. The findings from the present study highlight the necessity of avoiding mobile phone usage during stair negation to prevent accidental stair falls. They also have practical implications for developing effective fall prevention interventions.

Construction workers usually use hammer drills to drill holes into hard materials for anchors or concrete screw installations. Vibration emission in the drilling process can cause various occupational diseases. Workers influence this process mainly by varying the feed force. A feed force variation in hammer drilling causes a machine-specific motor speed reduction. As it is impossible to distinguish the effect of feed force on vibration and productivity from machine-specific motor speed reduction effects, the findings of various studies on hammer drilling vary considerably. The goal of this study therefore is to identify the feed force effect on vibration and productivity, thus excluding machine-specific effects due to a motor speed reduction. We modified a hammer drill to keep motor speeds constant over a wide feed force range and conducted a drilling study using an automated drilling test rig. The drilling productivity increased with higher feed force, whereas machine-specific motor speed reduction led to a decrease. Evaluated with Cohen's f, both factors had a large effect (feed force: f = 0.62, motor speed: f = 0.42). An increasing feed force led to a higher vibration emission with a large effect (f = 1.03). Motor speed reduction reduced vibration with a small effect (f = 0.21). Further hammer drill studies are needed to specify machine-specific motor speed reductions for comparing the results of different studies. The isolated effects could be used by manufacturers to implement control strategies for automatic optimizations. Based on the feed force, motor speed could be varied to optimize vibration or productivity.

The design of tractor pedal affects operator's comfort, working efficiency, and occupational health. To optimize tractor clutch pedal design parameters, we conducted a single-factor experiment and a response surface experiment based on a biomechanical model. The experimental indicators included the biomechanical loads of major activated muscles and joints of the lower limb, and the experimental factors comprised pedal-seat horizontal distance L, pedal-seat vertical distance H, and pedal spring stiffness k. The results indicate that L and H mainly influence the loads of semitendinosus and hip. Semitendinosus activity and hip torque first decreased and then increased with increasing L (or H), reaching the lowest level at 82 cm of L (or 42 cm of H). The increase in k led to gradual decreases in iliopsoas activity and increases in semitendinosus, rectus femoris, soleus activities, and ankle torque, as well as a first decreasing and then increasing trend of hip and knee torques. The overall biomechanical loads of the lower limb first declined and then grew with increasing L, H, and k. The optimal range of clutch pedal design parameters was calculated to be {(L, H, k) | 36≤L ≤ 40, 72≤H ≤ 76, 14≤k ≤ 22} when using the response surface method. Within this range, muscle activity and joint torque were reduced by 14.2% and 51.6%, respectively, indicating effective alleviation of the lower limb biomechanical loads. This study provides important implications for the biomechanical analysis of tractor operator-pedal interaction system and lays a foundation for improving the design and comfort of tractors.

Earplugs are widely used to prevent noise induced hearing loss. However, the discomforts they induce negatively impacts their effectiveness by influencing their consistent and correct use. The physical earplugs discomfort is related to the user perception resulting from biomechanical and thermal interactions between the earplug and the earcanal. Its main attributes are “physical annoyance”, “pain”, “pressure” and “irritation". The (dis)comfort results from the complex interactions between the wearer, his/her earplug, and his/her work environment, which form the concept of triad. This study aims at improving our understanding of the physical discomfort of earplugs by identifying the triad characteristics that have a significant influence on the main attributes of the physical discomfort. The (dis)comfort of earplugs was assessed in the field with 173 participants who tested 7 different earplugs models over 7 weeks and answered comprehensive comfort questionnaires. Triad characteristics were assessed both with questionnaires and in laboratory using comfort testers. Statistical analyses enabled to identify main characteristics of the triad that influence physical comfort attribute including the earplug radial force, extraction force and friction coefficient. Characteristics of the work environment (work duration) and of the person (i.e., ear morphology, past experience with earplugs), were shown to influence physical discomfort. Results of this study could provide tools to manufacturers so that they can design earplugs taking into account comfort aspects and to preventionists so that they can propose to workers the earplugs that are the most adapted to them and to their work environment.

Background

Consumer health information technologies (IT) are being increasingly applied to improve access to self-care resources for individuals with chronic illnesses. Thus, it is important to identify the factors influencing the patients’ adoption or rejection of these technologies.

Objective

This study contributes to the literature on consumer health IT adoption by identifying the facilitators and barriers to the use of a computer-based chronic disease self-monitoring system by patients with type 2 diabetes mellitus and/or hypertension.

Methods

Semi-structured interviews nested within a 3-month randomized controlled trial were conducted with 38 patients. Guided by the home care health IT implementation framework described in Or et al. (2009), their data were contented analyzed.

Results

The facilitators and barriers identified were organized around the six variable categories of the Health IT implementation framework, including patient attributes, technological characteristics, patient–technology interaction, home environment, organizational factors (e.g., influences, resources, and support), and patient outcomes.

Conclusions

Our study provides a holistic insight into the conceptualization of consumer health IT adoption by patients. When creating and implementing consumer health IT, taking into account the identified facilitators and barriers might boost the likelihood of technology adoption.