AHFE Open AccessPhysical Ergonomics and Human Factors
Editors: Ravindra S. Goonetilleke, Shuping Xiong
Topics: Physical Ergonomics and Human Factors
Publication Date: 2023
ISBN: 978-1-958651-79-7
DOI: 10.54941/ahfe1003027
Articles
Development of a Comprehensive Human Factor and Ergonomics Checklist for Workplace Inspections Using a Macroergonomics Approach
Lack of time and manpower as well as a fragmented inspection process are some of the challenges faced by industrial hygiene inspectors from the Malaysian Department of Occupational Safety and Health (DOSH) in carrying out their duties especially regarding industrial hygiene and ergonomics related workplace inspections. To streamline the inspection process and ensure a comprehensive assessment of the workplace, a study was carried out to develop a comprehensive Human Factors and Ergonomics (HFE) checklist. To our knowledge, there is no publicly available checklist covering all three ergonomics domains (physical, cognitive and organizational) that is designed to facilitate workplace inspection and regulatory enforcement process by industrial hygienists and inspectors.The study was divided into several phases. During the first phase, a literature review was carried out looking at existing checklists, assessment methods and industrial hygiene and ergonomics standards that fell within the scope of our study. During this phase, the applicable local regulations and current enforcement methods by inspectors were also analyzed. Based on this a draft checklist was developed. The checklist utilizes a macroergonomics approach where the different socio-technical components of the work system are assessed: the design of each task, the personnel carrying out the task, the physical environment the task is being carried out as well as the management systems and culture of the organization. To encourage a more holistic approach to assessing HFE, the checklist also borrows techniques from diverse fields outside of industrial hygiene such as human error engineering, organizational psychology, and industrial design.The second phase of the study involved multiple discussion sessions with DOSH inspectors, academics and professionals in various fields and industry to further refine the checklist so that it can be used both by inspectors carrying out workplace inspections as well industrial hygienists and safety practitioners to identify areas for improvement in their own workplaces. The checklist was also tested at by safety practitioners at 2 workplaces and by DOSH inspectors at 7 workplaces. During the tests, both regulatory inspectors and industry safety practitioners gave positive feedback on the approach and scope of the checklist. The inclusion of lesser-known elements related to cognitive ergonomics and organizational psychology were well-received even though these are not explicitly regulated by local law. However, since a macroergonomics approach was used in the checklist, there were concerns raised regarding the level of detail and time required to complete the checklist.The checklist is still being developed and the next phase of the project which will start in 2023 includes a Pilot Program where in-depth testing of the checklist will be undertaken at multiple workplaces in different industries throughout the country.
Shalinda Shafie, Shamsul Bahri Mohd Tamrin, Ng Yee Guan, Dayana Hazwani Mohd Suadi Nata
Open Access
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Conference Proceedings
Stability assessment of electromagnetic pulse neck massagers
Electromagnetic pulse massage mimics the current signal of human nerve fibers by conducting a weak current to the deeper layers of the skin, which makes the muscle fibers contract and imitates massage techniques such as pounding and kneading, thus achieving a relaxing effect on the cervical spine. Wearing stability of such products largely affects the effectiveness and comfort of massage. This paper aims to investigate the wearing stability and influencing factors of electromagnetic pulse neck massagers. Three representative neck massagers were used for testing, and subjective ratings of fit were collected from 58 participants (29 males, 29females), along with measurements of wearing slipping distance and neck dimensions. The results showed that females wore the neck massager significantly more loosely than males and had a longer slipping distance of 10.256mm. Moreover, the correlation analysis indicated that the wearing fit was strongly correlated with Middle Neck Width (MNW), moderately correlated with Middle Neck Girth (MNG), weakly correlated with Root Neck Girth (RNG) and Front Neck Length (FNL), which was a guideline for the design of size and grading for neck massages.
Yiteng Sun, Zhelin Li, Lijun Jiang
Open Access
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Conference Proceedings
An integrated FUCOM-ARAS model for ergonomic risk assessment
Many workers suffer from occupational musculoskeletal disorders and mental burdens in workplaces. A number of ergonomic risk factors such as human-related, cognitive, and physical contribute to inducing these burdens in the workplaces. Thus, ergonomic risk assessment is conducted to determine these risk factors and to reduce their negative effects by providing safer and healthy working environments. The aim of this study is to introduce a new ergonomic risk assessment approach for revealing the most important ergonomic risk factors and the worker who is most affected by these risk factors while performing tasks in a distribution center. For this reason, an integrated multi-criteria decision-making (MCDM) model which consists of the Full Consistency Method (FUCOM) and Additive Ratio Assessment (ARAS) methods to achieve the purpose of the study has been developed in this study. The FUCOM method is applied to calculate the weights of human-related, cognitive, and physical risk factors, separately. Then, the ARAS method is used to determine which worker has more exposed to ergonomic risks. This study can contribute to occupational safety managements of the companies to conduct more systematic ergonomic risk assessment activities and prepare effective ergonomic improvement programs.
Şura Toptanci
Open Access
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Conference Proceedings
Ergonomics, Health and Safety Challenges in the Construction Industry and the Role of Industry 4.0
Construction is a physically demanding process, and its activities entail exposure to a range of health and safety (H&S) and ergonomics hazards and risks. Inadequate H&S and ergonomics in turn negatively impact the health and wellbeing of workers and overall project and business performance. Given these realities and the persistence of H&S and ergonomics hazards and risks, a quantitative study was conducted to interrogate the related issues and evolve a response, including the potential of Industry 4.0 (4IR) technologies to contribute to an improvement in related performance. The study included members of the Association of Construction Health and Safety Management (ACHASM) who completed a self-administered questionnaire. The findings indicate: industry is still focused on the traditional parameters of cost, productivity, and time; workers are exposed to H&S and ergonomics hazards and risks; H&S- and ergonomics-related performance impact on overall project and business performance, and 4IR technologies have the potential to contribute to improving H&S- and ergonomics-related performance. Conclusions include: the construction process and its activities entail exposure to ergonomic hazards and risks; the construction process and its activities are physically demanding and militate against the health and wellbeing of workers; H&S plays a synergistic role in overall organisational and project performance, and there is a low level of awareness of the potential of 4IR technologies to improve H&S and ergonomics performance. Recommendations include: the holistic benefits arising from optimum H&S and ergonomics should be documented; designers should consider the impact of design, details, and specifications on construction H&S and ergonomics; contractors should interrogate the methods adopted to undertake construction activities to mitigate hazards and risks, and awareness with respect to the potential of 4IR technologies to contribute to improving H&S and ergonomics performance should be raised.
Simamnkele Ngxesha, Claire Deacon, John Smallwood
Open Access
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Conference Proceedings
Manual handling in health care sector using kinaesthetic techniques
The proper mobilisation of patients affects not only the health of the caregiver but also the patient himself, since it is a critical condition for preventing treatment failure and avoiding strain injuries from pressure and wrong placement.Professional experience, using standardised handling techniques, can be modified using kinaesthetic approach.The kinaesthetic is a self-perception discipline, based on proprioception, that is, the capacity to feel and perceive the posture of the body in space, its movements and muscle contractions, also without visual input. This thecnique applied during positioning and handling presupposes, on the one hand, respect for the functional anatomy of the patient and, on the other hand, the protection of the operator performing the handling.Kinaesthetic can contribute significantly to reducee biomechanical load and to improve healthcare outcomes.By using an optoelectronic system (SMART-DX 6000 System, BTS, Milan, Italy) and 6 spherical reflective markers placed at selected landmarks (c7, bilaterally scapular acromion, sacrum, bilaterally anterior superior iliac spine (Davis, 1991)), the trunk kinematics of a worker was recorded during several patient handling tasks (lateral decubitus, sitted placement, lateral shift, side displacement, downward displacement) with (CNSTTC) and without (CTRL) kinaesthetic. Then, the ranges of motion (RoM) of the trunk in the three planes of space were calculated. Muscular activity coactivity was also recorded through sEMG from the following muscle bilaterally: Erector Spinae, Rectus Abdominis, Rectus Femoris, Biceps Femoris, Anterior Tibialis and Gastrocnemius Medialis. The co-activation index is a parameter that provides the percentage of simultaneous activation during each task of the antagonist muscles of the trunk and leg. It has been shown in previous literature studies how increased co-activation can be disadvantageous for the jointsThe most relevant kinematic results are in the trunk. Trunk flexion is reduced in all the analyzed tasks when using kinaesthetic approach. Otherwise kinematics results showed increased values of RoM for trunk lateral bending in all tasks but sitted placement.About sEMG results showed a decreased co-activation of the trunk muscles in lateral decubitus, sitted placement and side placement. Co-activazion of the legs showed decreased values for lateral shift,, side placement and downward displacement. was substantially unaffected except for lateral decubitus where kinaesthetic showed an increased value of coactivation.These are preliminar results that should be confirmed with a larger sample of experienced workers. Moreover it could be advisable to identify some sub-tasks from each subtasks that might be more noticeable from an ergonomic point of view.
Alessio Silvetti, Giorgia Chini, Tiwana Varrecchia, Francesco Draicchio
Open Access
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A Failure Event Virtual Learning Method that Replaces Field Experience and Its Effectiveness Measurement
Its known that 95 % of occupational accidents are caused by unsafe human behavior. Therefore, in order to prevent occupational accidents, various human resource education is implemented in each company, but due to the rut that accompanies continuation, many of them are only aimed at preventing serious accidents in steady state. Furthermore, since it takes time and manpower to conduct education, there is also a problem that these educational methods are not effectively utilized in the field. For example, in recent years, a method of supporting risk prediction using VR in high-place work has been considered, but it costs a lot of money to introduce it, and people who have little experience in the first place have the problem that it feels like a game. Merely continuing such a stereotyped education will not improve learning through experience, and it will be difficult to develop outstanding human resources with awareness. Furthermore, for those who have little experience in the field, even if they acquire knowledge through classroom lectures and group work, it is difficult to use it in the field and predict danger. Developing experienced and excellent human resources who can notice on-site is an urgent issue for the future of the company. Therefore, in this research, by investigating various conventional educational methods and sorting out their strengths and weaknesses, we will clarify the reasons why these educational methods are not being used in the field, improve the weaknesses, and improve the actual field. We propose a failure event virtual experience-based l learning method that replaces the field experience.In this study, we decided to measure the effect of the proposed learning method from the degree of awareness in the accident prevention activities carried out in Japanese companies. The reason for this is that in order to further improve the effectiveness of current safety education, it is most practical to measure awareness during activities that are actually carried out in the field, and it is not possible to measure with paper tests or questionnaires. Therefore, based on the characteristics of on-site workers, we decided to examine methods to improve their awareness and willingness to participate in safety activities. Furthermore, we decided to conduct an analysis based on an evaluation experiment to see if the subject's awareness improved by receiving the proposed educational method prior to the safety activities.
Yusaku Okada, Takafumi Aoyagi
Open Access
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Conference Proceedings
Expansion of the System for Collecting Information on Hospital Incidents - Aiming to revitalizing on-site management
In medical facilities and general hospitals, a variety of information regarding incidents in patient care is collected and analysed. However, due to the large differences in knowledge and experience of on-site risk managers, previous studies have shown several problems with the data collected. Underlying these problems is the analyst's limited knowledge of human factors, IT, and management. However, it is very difficult to give more time and cost for safety training to on-site risk managers. Therefore, in this study, we decided to organize the results of past research on human error factor analysis from the perspective of on-site management. As a result, we were able to obtain a set of elements [elements for activation of on-site activities] for improving the ability of on-site risk managers to recognize, the willingness of on-site risk managers to participate in medical safety activities, and the management level of on-site risk managers. Based on the "Elements for Activation of On-Site Activities", we developed a prototype of an incident reporting support system.
Yuriko Imura, Yusaku Okada
Open Access
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Conference Proceedings
Fixation analysis of affective picture processing in aggressive adolescent
Aggressiveness is an emotional state associated with physical or verbal violence or destruction towards others or oneself. Aggressive behaviors in adolescents are a frequent reason of consultation in mental health care services because it generates negative consequences in the life of the person and their environment, in addition, it increases the probability of school dropout, psychiatric disorders and substance abuse. The study contemplates the presentation of images with positive valence and images with negative valence of the set IAPS to 60 adolescents who were previously evaluated with CAPI-A test, divided into 30 adolescents with aggression and 30 without aggression. The results were analyzed through an eye tracker and indicate the existence of bias in the visual attention of aggressive adolescents towards negative stimuli, while that non-aggressive adolescents tend to focus on positive stimuli.
Diana Pacheco, Andrea Argudo-Vásconez, Patricia Margarita Ortega Chasi, Martha Cobos, Omar Alvarado
Open Access
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Musculoskeletal and work practice survey of chainsaw users in the New Zealand forest industry
Forestry is one of the most dangerous occupations globally, and manual work involving the use of chainsaws present a significant health risk to its workers. Over the last 10 years, there have been 810 chainsaw-related incidents reported in the New Zealand (NZ) forest industry. The aim of this study was to undertake a survey of chainsaw operators in NZ to obtain information on the risks associated chainsaw use, the prevalence of self-reported musculoskeletal complaints, and opinions on the safe use and design of chainsaws and corresponding safety equipment. An anonymised, electronic questionnaire survey was distributed to forest companies by forest sector organisations. The questionnaire was divided into three main components: 1) demographics; 2) self-reported musculoskeletal disorders (a modified version of the Nordic musculoskeletal questionnaire); and 3) chainsaw-related accidents, injuries, and work practices. Descriptive statistics and parametric and non-parametric statistical tests were used to compare differences between frequent (used a chainsaw at least 2 or 3 times per week during the last 2 years) and infrequent chainsaw users. Fifty-seven workers responded to the questionnaire, which was considered a low response rate based on the size of the forest industry in NZ. Approximately 47% of respondents had a BMI of >30, classified as ‘obese’ based on the World Health Organisations BMI classification. Low back pain (51%) was the most frequently reported complaint over the last 12 months, followed by shoulders (36.8%), hands/wrists (33.3%) and knees (31.6%). Approximately 65% of all respondents considered their musculoskeletal symptoms were due to work and 60% felt the injury had restricted their normal work activities to some extent. Frequent chainsaw users did report slightly higher prevalence rates of musculoskeletal complaints across most body parts during the last 12 months. The risk factors considered to add to the physical workload and risk of MSD in chainsaw operators were: “bending over all day”; the repetitive nature of the work; the weight of equipment carried in addition to the chainsaw (e.g. first aid kit, safety chaps, fuel cans, oil, wedges); slips, trips and falls when walking between trees; and limited training opportunities for improving techniques and working postures. The high prevalence of work-related musculoskeletal conditions and the multifaceted nature of risk factors presents unique challenges to improving the health status of NZ forest workers. Interventions should consider a range of individual, physical, psychosocial, and work organisational approaches. Beyond modification to work practices, further consideration should be given to educating and promoting a healthy lifestyle among these workers. Frequent chainsaw users do appear to be at increased risk of musculoskeletal complaints. Some caution is needed when interpreting findings from the survey as the estimated overall response rate was considered low.
Mark Boocock, Liz Ashby, Richard Parker
Open Access
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Conference Proceedings
Evaluation of ergonomic needs among female sewing machine operators in garments industry of Bangladesh: a pilot study
The enrichment of the garments industry in Bangladesh has given employment to millions of people, especially women. With cellular manufacturing, enhanced productivity accompanies increased musculoskeletal disorders risk (Shaheen A., Mohammad Z.R, 2014). Sewing operators working posture is a vital factor related to musculoskeletal symptoms (Dianat et al., 2015). However, there is limited research on the ergonomic needs evaluation among Bangladesh female sewing machine operators.Seven female sewing machine operators in a garment manufacturing unit in Dhaka, Bangladesh, were recruited for this pilot study. A combined survey sheet was developed to record demographic information and CMDQ questionnaires. The demographics included age, weight, height, marital status, and education level. CMDQ is a survey sheet to evaluate the rating of symptoms in specific body parts (neck, shoulder, arm, upper back, lower back, leg) by multiplying the frequency, severity, and interference scores. Anthropometric measurement and sewing facilities (table and chair) dimension measurement were conducted. Subjects were interviewed about their subjective opinions on the ergonomic functions of sewing machine facilities.Participants were 31.6±8.8 years old, 56.4±8.4 kg, and 5.27±0.35ft. They are married, and their educational levels range from class 5 to 8. A typical daily work process of a female sewing machine operator in a garment manufacturing unit in Bangladesh is constantly sitting for more than 10 hours with a 1-hour lunch break. They hardly move around, only to pick up their work in the morning and submit their production to their supervisor at the end of the day. After a whole day of work, four people reported lower back pain, while three reported neck pain, 2 with leg pain, and 1 with arm pain. Lower back got the highest discomfort score (26.5), followed by neck (10), arm (7), and leg (3). The mismatch computations between body and facility dimensions showed that the current design of sewing facilities is unsuitable for female workers. The seat height is too low, and the hip width is too narrow for them. According to interviews, subjects complained about their current working chair without elbow rest which was quite uncomfortable for them to work. It could be one of the reasons that a worker is facing severe arm pain. Consistent with anthropometric measurement results, several subjects mentioned that the seat and desk height was inappropriate for them. They had to use a cushion on the seat to make them more comfortable.In conclusion, female sewing operators in Bangladesh's garment industry face a high risk of musculoskeletal disorders with mismatched facility dimensions and little consideration of their ergonomic design. A better understanding of their ergonomic needs involving sewing operations can potentially impact workers' quality of life and national productivity.
Samia Rafique, Jecha Suleiman Jecha, Hui Lyu
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Design and Verification Methodology of the Pilot's View of Civil Aircraft Non-openable window
The design goal of Pilot compartment view is to provide the necessary view for the safe flight of the crew under any scenario.For non-openable window aircraft,the design and verification of pilot’s view are summarized into three levels by establishing fault trees with insufficient pilot’s view,and specific design considerations and verification methods are proposed for each level.
Feng Zhixiang, Yuhe Mao
Open Access
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Conference Proceedings
Influence of the shape of a forearm support on the range of pronation and supination in the context of a surgical arm assistance system
Surgery often results in static, uncomfortable arm and upper body postures, which lead to high stress on the surgeons' upper extremities [Szeto 2012]. To counteract this, an interaction-based arm assistance system has been developed to physically unload the surgeon's upper extremities during laparoscopic procedures. This is achieved by actively supporting the forearms. Thereby, a supporting force acts on the forearms, which follows the natural forearm movements without restrictions [Karlovic 2015]. The assistance system is controlled exclusively by a form fit and frictional connection of the forearms with the arm support. Investigations show an influence of the anthropomorphic shape of the form on objective and subjective operability and an advantage of the anthropomorphic shape over no support and a flat form [Langer 2022]. In this study (funded by the German Research Foundation), the range of pronation und supination within anthropomorphic forms is investigated to design the human-machine interface of the arm assistance system for precise surgical tasks with forearm rotation. Within the scope of this research project, the interface parameter shape of the forearm support is therefore investigated on the basis of five shape variants (gender-specific negative shapes of 05-, 25-, 50-, 75- and 95-percentile adults). To investigate the range of motion of pronation and supination, the 32 subjects grasp a round handle, which is oriented orthogonally to the ground (start position). The forearm is bent 90° to the upper arm (flexion). On instruction, the subjects rotate their forearm maximally in the pronation direction and then in the supination direction. The maximum angles achieved in each case are measured starting from the start position. The subjects then rate the comfort and further properties of the shape on a 7-point Likert scale. This is repeated with all shape percentiles. The study shows that the percentile of the anthropomorphic form has an influence on the range of motion in pronation and supination of the forearm. Compared to no support of the forearm (Ø-pronation = 76.4°, Ø-supination = 114.3°), the average range of motion for support with the 05-percentile form (smallest shape) decreases by 8.4% (70.6°) for pronation and by 22.5% (93.3°) for supination. In contrast, the average range of motion for support with the 95-percentile form decreases by 5.3% for pronation and 18.1% for supination. For pronation and supination, the trend shows that the smaller the shape of the forearm support, the smaller the average range of motion. The average range of rotation that can be achieved without support and without form is not achieved with any form. The subjective survey shows that comfort is lowest for the smallest form. Furthermore, the correlation of the range of motion of the different forms is evaluated depending on the forearm percentile of the subjects. Design recommendations for the shape of the forearm support are derived from the results. It is deduced that a forearm support with rotational degrees of freedom for pronation and supination could offer an advantage for the preservation of the range of motion and consequently for the performance of tasks.
Ferdinand Langer, Thomas Maier
Open Access
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Anthropometric Evaluation of University Classroom Furniture
The objective of this study is to evaluate four types of university classroom furniture. The methods of evaluation included the individual comparisons equations method and the percentile values method; both are anthropometric methods. The third method is a questionnaire-based subjective evaluation method aiming at studying students’ satisfaction. The evaluated furniture dimensions were seat height, seat depth, seat width, backrest height, desk height and underneath desk height. The measured anthropometric dimensions were stature, hip breadth, elbow rest height, shoulder height, knee height, popliteal height and buttock-popliteal length. They were collected from 80 students (half males, aged between 20 to 39 years). The individual comparisons method showed relatively lower percentages of match between the furniture dimensions and student anthropometry. While, the percentile values method showed relatively high percentages of accommodation. Results of the questionnaire showed that the majority of students were satisfied with their preferred designs.
Ahamed Altaboli, Hana Aliskandarani, Ala Alshaikhi, Hager Alahmar, Ruwida Muttardi
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How do the antagonistic muscles contract during modulating the output force?
Muscle forces or joint loads during daily living are important data for designing assistive devices or interfaces. Since it is difficult to measure them, they are usually calculated by static or dynamic simulations. However, such simulation requires some assumptions to solve the statically indeterminate problem, which is, the number of muscles is larger than the number of the static or dynamic conditions. One reason for the indetermination is the simultaneous contraction of the antagonist muscle. Antagonist muscles are considered to be exerted to increase the stiffness of the joint, however, it is not used as the condition to solve the indeterminate problem yet, because there is no quantitative evidence. We have assumed that the antagonist would contract during modulating the output force sensitively. Although we already confirmed the assumption by simulation, the experimental support to show the validation had been lacking. Therefore, we performed the experiment to confirm the assumption using the upper limb. Test subjects were asked to grasp a handle with a force sensor and push/pull it; by maximum force, about half of the maximum force, and the half force by monitoring the output of the force sensor with inputting some unpredictable external force. EMGs of the biceps and triceps brachii were measured. As a result, the antagonist was exerted only in the condition of monitoring the force to modulate the output. Our future plan is to confirm the relation between the magnitude of the antagonist exertion and the sensitivity to modulate the output force.
Michihiko Fukunaga, Ryoga Fujioka, Yuta Kawasaki
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What is the repercussions of the introduction of a cobot on productivity and biomechanical constraints on operators in a collaborative task?
Collaborative robots, or cobots, are robots designed to closely collaborate with a human in a shared workplace. Introducing a cobot in a collaborative work situation aims to preserve productivity without impair the operator’s health, even improve them. Musculoskeletal disorders (MSDs), main occupation diseases in Industry, are pathologies of multifactorial origin, as biomechanical solicitations are one of them (e.g., posture, repetitiveness).This paper evaluates the repercussions of the introduction of a cobot in a collaborative task with two studies: first to compare a task in collaboration with a cobot or a human co-worker and second to analyze the impact of pace (i.e., rhythm and leader); both on productivity, quality of interactions, operator’s posture and attentional demand.Thirty-four participants in Study 1 and twenty in Study 2 performed a collaborative task inspired by assembly lines in factories, in collaboration with a co-worker. In Study 1, this co-worker was either a human or a YuMi cobot, participants were always the leader; in Study 2, the co-worker was always the YuMi cobot; the leader was either the participants or the cobot, and in this last case, different paces were imposed. Productivity was measured with the number of products manufactured, quality interactions with the rate of idleness and activity of participant and co-worker and interactions rate between them, participant’s posture with joints angles and RULA evaluation and attentional demand with performance at a second task.In Study 1, productivity was less important with the cobot than with a human, with less interactions and with higher attentional demand. However, posture was less risky with the cobot for operator health in terms of MSDs. In Study 2, productivity and attentional demand increased with the pace until a threshold at the mean-imposed pace. Posture was riskier for operator health in terms of MSDs only for the fastest imposed pace.In Study 1, deterioration of productivity and quality of the interactions with the cobot co-worker was mainly due to the limited capabilities of the cobot. Results about posture were also linked with pace, but differences were also observed during operator’s activity with less biomechanical solicitations working with the cobot than with the human for the same actions. Leading or following the pace seemed to not influence these variables in Study 2. Thus, the results of Study 2 seemed to indicate that the differences between human-human and human-cobot interactions observed in Study 1 were mainly due to the slower pace due to the cobot, except for the better posture which could be linked with the introduction of the cobot.Even though the experiment took place in a laboratory, the task was strongly inspired by the field and the results are consistent with those in the literature. These results therefore allow us to establish solid hypotheses that can be generalized to real situations in a factory, especially concerning the improvement of the posture when the operator is facing a cobot.
Kévin Bouillet, Sophie Lemonnier, Fabien Clanche, Gérome Gauchard
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Assessment of risk factors of upper limb musculoskeletal disorders in a meat processing plant
The aim of this study was to evaluate the risks associated with repetitive movements of the upper limbs in different meat processing tasks of a pig slaughterhouse, using the OCRA Checklist. The study was conducted in a Brazilian pig slaughterhouse with 1,000 workers, divided into two work shifts. To evaluate the risks associated with repetitive movements of the upper limbs, 10% of the workforce was assessed while carrying out their work tasks, using the checklist proposed by the OCRA method. Descriptive statistics and the Student t-test (SPSS 17.0) were applied to compare the risks between both sides of the workers’ bodies (p≤0.05). There were 39 work activities analyzed from the productive sectors. The average of occupational repetitive actions performed by workers was 54.5±20.8 per minute, representing 7 points on the OCRA scale (0 to 10 points). The average score of the OCRA Checklist was 18.8±6.0 (medium risk). The scores for the right upper limb (18.6 - medium risk) differed statistically (p=0.016) from the left upper limb (13.8 - medium risk). Five work tasks were considered high risk, 29 were classified as medium risk, one as low risk, one as very low risk and three as acceptable risk. Performing simulations in 32 of the 35 activities made it possible to reduce the UL-WMSD risk to very low levels, by only decreasing the work pace. In three of the activities, a very low risk level could not be achieved by only reducing the work pace, due to the high demand for strength required to perform these tasks. These results suggest that most pig processing tasks, classified as high (13%) and medium risk (74%), predispose workers to a greater probability of developing upper limb work-related musculoskeletal disorders (>21.5% probability for high risk and 10.8 to 21.5% for medium risk). Simulations of decreasing the work pace showed the effectiveness of this organizational measure to reduce the risk of UL-WMSDs.
Diogo Cunha Dos Reis, Antônio Renato Pereira Moro
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Exploration of Back Exoskeleton’s Effectiveness on Transportation Maintenance Workers during Lifting Activities
Safety statistics from Indiana Department of Labor showed that the transportation and warehousing industry has the second highest number of reported occupational fatalities (26) in 2020. One major cause of occupational fatalities is ergonomic issues including excessive force, repetitive motion, and awkward posture. These ergonomic issues have already been extensively studied and corresponding solutions were developed for the building construction activities. However, transportation activities are different from building construction activities in duration, intensity, and frequency. In addition, there lacks studies exploring whether the proposed solutions to ergonomic issues of building construction could also solve the ergonomic issues of transportation activities. To this end, field experiments were conducted with 29 transportation maintenance workers between August 9th 2023 and September 23rd 2023 at a transportation maintenance unit of Indiana Department of Transportation (INDOT). Lifting bags of dry concrete mix was identified as the activity of top concern, according to (1) the perception of which activity most likely to cause an injury to back or shoulder, (2) the frequency of performing the activity, and (3) the number of historical sprain injuries caused by the activity. Therefore, the participants were asked to lift 12 bags of three different weight of dry concrete mix with and without a back exoskeleton. Specifically, three different weights of bags include: 80-pound bags (weight of bags that INDOT maintenance workers mostly use), 50-pound bags (weight of bags that INDOT maintenance workers sometimes use and which is recommended by Recommended Weight Limit equation under the ideal condition), and 31.5-pound bags (recommended weight of bags based on applying values from real lifting practice of INDOT maintenance workers into the Recommended Weight Limit equation). The participants need to lift bags from a pallet to a truck with liftgate, have a five-minute short break, offload those bags from the truck with liftgate to the ground, and then have a 20-minute long break. Skin conductance and heart rate, as the key indicators of physical fatigue, were measured during the lifting activity. In addition, perceived level of muscle exertion was also collected by using a Borg 6-20 scale during two experiment breaks of each trial for indicating level of fatigue risk level from low to very high. After performing a paired t-test of collected data, it shows that the back exoskeleton does not significantly help workers reduce physical fatigue risks while transportation maintenance workers lift 31.5-pound bags. However, the back exoskeleton can significantly lower the physical fatigue risks when transportation maintenance workers lift 50-pound bags and 80-pound bags. This study not only fills the gap of exploring the effectiveness of back exoskeleton implementation in transportation maintenance activities, but also provides evidence and practical recommendations for transportation workers, managers, and organizations that a back exoskeleton could reduce the level of fatigue risk when lifting materials with weight of 50 pounds and above.
Xingzhou Guo, Xinran Hu, Yunfeng Chen
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Differences in Circulating Cortisol Levels After Completing Hand Ergometer Exercise with and Without Graded Compression Arm Sleeves
Cortisol has many physiological effects on the human body and its concentration increases in an intensity-dependent manner. The prolonged physical stress increases total cortisol concentration. Anecdotal data suggests that using graded compression sleeves forearm alleviates pain in the upper and lower limbs. The physiological mechanisms underlying these benefits are not fully understood. This study aimed to assess the effects of wearing graded compression (13-18 mmHg) sleeves on circulating cortisol after completing a physical activity with three different intensities. The study included six participants between 18 and 25 years old without a known history of injuries in the upper limbs. The proper sleeve size was fitted to the participants following the manufacturer’s instructions (On-Site Therapy, Tallahassee,FL.), and anthropometric measurements were taken. All the participants randomly completed a cycle hand ergometer exercise at 60 RPM at 25 W., 50 W., and 75 W for a maximum of 10 minutes with and without forearm sleeves. All the participants rested for at least 72 hours before the next exercise session to avoid muscular fatigue. Venous blood samples were drawn before and after completing each session to compare the effects of wearing graded compression sleeves on the circulating cortisol concentration. Cortisol concentrations were analyzed by enzyme link immunosorbent assay (ELISA). A Linear mixed-effects model was used for analysis. Participants wearing the compression sleeves showed a significant decrease in cortisol concentration at 50 W only. This study shows the potential benefits of wearing compression sleeves while performing activities involving the upper limbs. Even though our results show a decrease in cortisol concentration at 50 W., a larger sample size would be needed to dictate a significant difference in the physiological response associated with the use of graded compression sleeves.
Manuel Gomez, Samuel Montalvo, Daniel Conde, Gabriel Ibarra-Mejia
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