International Journal of Industrial Ergonomics最新文献

Lack of situation awareness (SA) is a major source of human error in forklift operations. Effective assessment of SA levels is a critical link in improving the SA of forklift operators. Aiming at the intrusive, subjective and intermittent problems of current measurement methods, this paper proposed a SA recognition method based on eye movement and electroencephalography (EEG) features. A forklift operation experiment was designed in a real-life scenario, where eye movement and EEG data of forklift operators were collected, and the Situation Awareness Rating Technique (SART) method was used to calculate SA scores. Independent sample t-test and Mann-Whitney test were used to investigate the differences in eye movement and EEG indicators among participants with different SA levels. Finally, the classification models of K-Nearest neighbor (KNN), Random Forest (RF) and Support Vector Machine (SVM) were used to recognize the SA levels of forklift operators. The results indicated that the visiting time indicators, fixation time indicators and fixation count indicators in particular Areas of Interest (AOIs) are significantly different from the SA levels; The combined EEG indicators θ/β, (α+θ)/(α+β), θ/(α+β) in Frontal (F) lobe, Parietal (P) lobe and Central (C) lobe, and (α+θ)/β in P lobe and C lobe are significantly different from the SA levels; The average recognition accuracies of the models of KNN, RF and SVM are 90.61%, 94.18% and 91.15%, respectively, with the RF model having the highest recognition accuracy. The results confirmed that the method can be used to assess the SA of forklift operators in the real environment, which provides a new avenue for SA measurement.

A camera monitor system (CMS) provides side/rear views via in-vehicle displays by replacing the existing mirrors with miniature cameras. Two surveys were conducted to determine the overall perception of truck drivers toward CMS compared to the conventional mirrors and to identify the ergonomic CMS display layout. Thirty experienced truck drivers evaluated CMS compared to the existing mirror system using six evaluation measures (intention to use, safety, convenience, rapidity and accuracy, preference, and superiority). Each respondent also evaluated eight different layout design alternatives using seven ergonomic evaluation measures (rapidity, accuracy, safety, convenience, learnability, intuitiveness, and preference). The design alternatives were developed by combining the locations of two truck CMS displays – one is side display replacing the main and wide-angle exterior mirrors and the other one is front display replacing the front mirror. The study results revealed that truck drivers rated the CMS highly compared to the existing mirror system across all six measures, suggesting the need for further academic and industrial research/development and thereby wider introduction of truck CMS. Also, the layout wherein the side and front displays were positioned at the A-pillar and middle-top-of-windshield locations, respectively, was found to be the best and its design characteristics were: 1) spatial correspondence between the provided information and the in-vehicle location for both the side and front displays, 2) spatial compatibility with driver expectation for the side display, 3) reduction in the eye movement required for the front display, and 4) spatial compatibility by relative position between the side and front displays.

As the cost of rendering immersive virtual reality goes down, VR technology has the potential to improve the learning outcomes of educational and training programs. In this context, it is important to identify the advantages and pitfalls of using VR as a training tool. This review is an attempt to evaluate VR technology as a training tool and various factors that impact its effectiveness. It was found that virtual reality has been used and tested extensively in surgical training with mixed results. Apart from the effectiveness and the cost of VR as a training tool, the other factors that will influence the widespread adoption of this technology for training are skill retention and task interruption. If VR is to be used for longer training sessions, interruptions are inevitable in the form of restroom breaks, texting etc., and hence it is important to study their impact on learning outcomes. Hence, a brief review of these topics in the context of VR and learning has been included in this study. In conclusion, it was found that although the use of VR as a training tool holds a lot of promise, its widespread adoption will depend on its adaptability to different training settings and its impact on learning outcomes, including factors like skill retention and task interruption.

Background

Computer work often involves prolonged periods of static sitting, which can result in incorrect posture and increase the risk of developing musculoskeletal disorders and associated pain. The incidence of neck pain among computer workers is increasing due to the association with incorrect posture. To solve the problem accurately, it is necessary to correct the incorrect posture.

Objective

This study investigated how the angle and muscle activity of the upper body changed when a posture correction feedback (PCF) system was applied during computer work.

Methods

Fifteen healthy, young adults participated in this study that was conducted in two sessions of 16 min each: the first without feedback and the second with feedback. Neck and trunk angle changes of the participants, as well as cervical erector spinae, upper trapezius, and thoracic erector spinae muscle activation, were measured during computer work. Kinematic and kinetic data were analyzed using a two-way repeated analysis of variance.

Results

Neck and trunk flexion were reduced with the feedback system. Muscle activation of the cervical erector spinae significantly increased over time with computer use and decreased with feedback system use (p < 0.05).

Conclusion

Our study demonstrates the PCF system may be an effective tool for alleviating postural stress in the neck and trunk in an office setting.

Relevance to industry

The PCF system can assist computer workers in improving posture. This demonstrates ergonomic benefits and does not interfere with computer work, making it suitable for use in a real work environment. This can help prevent musculoskeletal disorders and associated pain resulting from prolonged computer work.

People's emergency evacuation behavior is heavily reliant on spatial knowledge. Different spatial cognitive ways shape spatial knowledge differently. To investigate the effect of different cognitive ways on people's wayfinding performance in an indoor fire situation. The study used a virtual reality simulation of a shopping mall environment, and 128 participants were recruited for the experiment. The experiment divided the participants into six groups and placed them in two scenarios, one with and one without fire. This study also explored two other intervention behaviors to improve the participants' evacuation behaviors. The results showed that participants who used navigation had shorter walking distances and wayfinding times than those who used the You are here (YAH) map. Secondly, participants in the fire scenario walked longer distances and took longer to evacuate than those in the no-fire scenario, and they perceived successful evacuation to be more difficult. Thirdly, the intervention behavior effectively improved the participants' evacuation behavior and increased the efficiency of the evacuation. The leader's intervention was more effective in helping participants evacuate than the range intervention in this experimental setting. The findings may advance the understanding of human evacuation behavior and provide important practical implications for people's safety and emergency preparedness in shopping malls.

Janitorial services are an essential part to keep workplaces functional. Janitors consider the job labor intensive, and that workload is increasing in recent years. The most impacted body parts are hand/wrist, shoulder, and back in this population. This paper reports a compendium of physical ergonomics exposure assessment using three observational methods. The composite Strain Index (COSI) for hand/wrist, Manual Task Risk Assessment (ManTRA) for shoulder, and Recommended Cumulative Recovery Allowance (RCRA) for shoulder and back, were chosen for their capability to capture the complex and dynamic nature of all tasks performed in a janitorial job. Forty-six unique cleaning task-location-tool combinations received assessments, and the risk scores from the three methods are compiled into a compendium. This information can help practitioners to estimate the risk for a job, or designers to plan jobs for a team of janitors so the risks can be mitigated with careful task assignments.

Virtual reality (VR) has emerged as a mainstream commercial technology with multiple sensory channels, including advanced user interfaces (human-computer). However, the number of users complaining of VR motion sickness (MS) has been rapidly increasing. In this study, VR MS was investigated using subjective questionnaires: simulator sickness questionnaire (SSQ), virtual reality sickness questionnaire (VRSQ), and fast motion sickness scale (FMS) and objective physiological methods: electrodermal activity (EDA). To track VR MS based on symptoms, a model was constructed by applying a polynomial regression method. In addition, this study attempted to determine whether there are differences in MS according to the degree of immersion in a VR environment. Twenty participants (10 males and 10 females) were exposed to a dynamic VR environment through a simple operation method using a head-mounted display (HMD). The coefficients of determination of the objective measurement components were high before and after the rest. In particular, both the SSQ and VRSQ were highest for disorientation, that is, dizziness disorder and difficulty concentrating. This suggests that the timing of the EDA signal data extraction with respect to the rest may be critical. In addition, subjects placed in an immersive VR environment performed the experiment in an unstable and dynamic posture; accordingly, the VR MS score was higher for subjects who participated in the experiment in a more dynamic position. Therefore, we confirmed the possibility of a significant association between VR sickness and postural stability. This study demonstrates the possibility of tracking MS in a dynamic VR environment according to intervals and symptoms using EDA signals, and the stability of posture should be considered in immersed VR environments.

Relevance to industry: The findings here provide insights into the model of tracking motion sickness using the EDA signal to prevent or reduce VR motion sickness. The EDA signal model can benefit the design or development of an immersive VR environment.

This study aimed to verify the direct and indirect influence of risk factors on the symptoms of WMSDs in the thigh, leg, and foot among workers in the inner regions of Brazil. Research tested a structural equation model (SEM) that describes hypothetical relationships between risk factors and WMSDs. Questionnaires were used to collect data on sociodemographic, occupational, biomechanical, and psychosocial factors, and pain symptoms about 420 workers. The results showed that different factors directly affect the thigh, leg, and foot. Maintaining the lower limbs in uncomfortable positions increases the chances of developing WMSDs in the thigh (β = 0.219; p-value <0.001), leg (β = 0.223; p-value <0.001), and foot (β = 0.158; p-value <0.01). Most psychosocial factors attenuate psychosocial stress, which in turn directly alleviates WMSD symptoms in the thigh (β = −0.502; p-value <0.001), leg (β = −0.315; p-value <0.01), and foot (β = −0.246; p-value <0.01). Factors were also found to uniquely affect aspects such as “another job” (β = −0.246; p-value <0.01) in the leg and effort (β = 0.146; p-value <0.05) in the foot. It was concluded that multiple factors influence the development of WMSDs in the lower limbs. These findings contribute to the existing knowledge on the causes of WMSDs and can help improve working conditions for the population under study. Therefore, managers and health, ergonomics, and occupational safety professionals can use the findings to develop more precise strategies to reduce the impacts of WMSDs on workers.

Irrelevant background sounds have been proven to decrease efficiency while working, while the perception may be different when people actively listen to pleasant background sounds at work. This study aims to investigate the cognitive workload in irrelevant speech-based information communication (live streaming, white noise, movie, songs, and quiet environment) with visual distractions under different reading tasks (familiar and unfamiliar reading material) using NASA-TLX and eye-tracking metrics. The results showed the main effect of irrelevant speech-based information type on NASA-TLX was not significant. Participants tended to show a higher preference for quiet-based information and the live-based information was the opposite. Revisits and fixation duration had a similar trend for a small window and movie-based information had the most revisits and fixation duration and white noise was the opposite. The results of this experiment will contribute to helping improve the pleasure perception while working and make communication information more efficient.