Physical Ergonomics and Human Factors

AHFE International

Accelerating Open Access Science in Human Factors Engineering and Human-Centered Computing

Physical Ergonomics and Human Factors

book-cover

Editors: Ravindra S. Goonetilleke, Shuping Xiong

Topics: Physical Ergonomics and Human Factors

Publication Date: 2022

ISBN: 978-1-958651-39-1

DOI: 10.54941/ahfe1002588

Articles

Ergonomics Evaluation Methods for Civil Aircraft Cockpit Layout

The design of aircraft cockpits tends to gradually become more and more human-centered, and the role of pilot in the cockpit has also been given more important responsibilities other than just flying the airplane. Therefore, the ergonomic design of the cockpit will largely affect the work efficiency and workload of the pilot, which can in turn affect the safety of the flight. In this paper, the objectives, objects and criteria of ergonomic evaluation of cockpit layout are defined, and the general evaluation process is put forward. In addition, this paper introduces several different ergonomics evaluation methods for civil aircraft cockpit layout, and recommends suitable evaluation methods according to the characteristics of the evaluation objects in different development phases of the cockpit.

Xinyang Zhu, Yang Zhou

Conference Proceedings

Effect of the backpack load on students’ discomfort

Backpacks are very useful in our day-to-day life, work, offices, and school. Especially students carry backpack to school every day with heavy loads of textbooks, notebooks, and laptop. This is an increasing concern of students carrying heavy backpacks in most countries. From the article of Huntsville Hospital, in the United States around 79 million students carry backpack to school. In 2007, more than 23,000 backpack-related injuries were treated at hospital rooms, physician offices and clinics. The load exerted from the backpack is one of the reasons of variations in the cervical and shoulder posture and it is suggested that carrying a backpack weighing 15% of body weight will be heavy for adults. This study evaluates the effect of backpack loads on the user discomfort in neck, shoulder, upper back, lower back, and knee during a walking activity. For this experiment, 12 participants were selected in the age group of between 18 to 21 years old from Lamar University. The backpack load which is exerted by the backpack was independent variable. As per the research, 15% of total weight of the body is the standard weight to carry the backpack during walking activity. Since, we have considered 10%, 15% and 20% weights of the backpack to the total body weight of participants. The user discomfort is considered as dependent variable. The walkway was embedded with three force plates with various backpack loads (10%, 15%, and 20%). Participants were told to walk on defined route for 10 minutes. After each task, participants had 5-minutes break and were asked to rate their discomfort level. The same procedure was carried out for all participants and measurement data were collected.The result showed a significant main effect of backpack load on the user discomfort of neck, shoulder, upper back, lower back and knee. The user discomfort with 20% load was significantly higher than that with 10% load for all 5 body parts. During the experiment, it was observed that female participant who weighs in range of 100-120 lbs. were experienced most discomfort and not able continue experiment when the weight of the backpack was more than 15% of the total body weight. Whereas the participants with the range of body weight around 160-180 lbs. experienced less discomfort in their neck and shoulder throughout the experiment. In conclusion, the research found that the backpack load significantly affects the user discomfort when student walk carrying the backpack. The research should have practical meaning to decide the appropriate weight of the students’ backpack and develop a more user-friendly design.

Nutan Ashok Chougule, Aliuddin Ahmed, Yueqing Li

Conference Proceedings

Effect of the shoe heel height on lower-limb muscle activity

Women often wear high-heeled shoes to make their feet look slender and tall. We focused on the muscle activity of the lower limbs and investigated how the presence or absence of shoes and the change in heel height affect the lower-limb muscles. The participants were eight women in their twenties, and the lower-limb muscle activity was measured while the participants wore running/low-heeled/high-heeled shoes. The surface myoelectric potential was measured for eight muscles around the knee/waist using a multi-channel telemeter as the participants walked on a treadmill. The root-mean-square myoelectric potential and thus muscle activity were significantly higher for bare feet than for wearing shoes. Additionally, there was no significant difference in muscle activity between low-heeled and high-heeled shoes, but the activity was less for these shoes than for running shoes. Thus, as the heel height in-creased, the muscle activity around the knee decreased whereas that around the lumbar spine increased.

Tamaki Mitsuno, Ami Sugawara

Conference Proceedings

Effects of carbon fiber insole on lower-extremity muscle activation and wearing comfort during treadmill running

Background and Objective: Although the role of shoes on sports performance and injury has been extensively examined, only a few studies investigated the effects from insoles. Recent studies on carbon fiber insoles (CFI) on athletic performance reported that CFI could improve sports performance by reducing energy loss and increasing energy return. However, there are scarce reports on the effects of CFI on muscle fatigue and wearing comfort. While stiffer CFI insoles are superior in energy loss reduction and energy return, they could increase more muscle activation to absorb the shock or provide more propulsive force to push CFI, leading to increased muscle fatigue and discomfort. Therefore, this study aims to evaluate the effect of CFI on lower-extremity muscle activation and wearing comfort during treadmill running. Methods: Three types of insoles were compared, namely CFI, CFI with cushioning (CFIC), and a benchmark commercial insole (COM). Fifteen healthy young men participated in the experiment. Each participant wore the same sports shoe, three different insoles in a random order, and ran on a treadmill at a speed of 10 km/h for 5 minutes. Surface electromyography signals of four lower-extremity muscles (Rectus femoris, Tibialis anterior, Biceps femoris, and Gastrocnemius medialis) were recorded in real-time for measuring muscle activation. After completing a trial run with each experimental insole, the participants provided their subjective ratings on perceived insole stiffness, energy support, overall comfort, and fatigue. Analysis of variance (ANOVA) and post-hoc grouping analysis were conducted to statistically evaluate the effects from three different insoles. Paired t-test was performed to compare CFI and CFIC and explore any cushioning effect. Results: In terms of lower-extremity muscle activation, even though CFIC and COM showed no significant difference for all four lower-extremity muscles, CFI induced a marginally significant increase of 1.5% on Gastrocnemius medialis (p = 0.063) and a significant reduction of 0.7% on rectus femoris (p=0.011) than COM. For the subjective ratings, both CFI and CFIC were significantly stiffer than COM (p < 0.001), but there were no significant differences in overall comfort, energy support, and fatigue. Compared with CFI, CFIC significantly reduced Gastrocnemius medialis muscle usage by 2.1% (p = 0.012) and was marginally less stiff (p = 0.102).Conclusions: This preliminary study showed that the carbon fiber insole CFI induced higher calf muscle usage and was perceived to be stiffer during treadmill running, which could contribute to provide the propulsive force for better sports performance. Carbon fiber insole with cushioning (CFIC) can help to relieve muscular fatigue. Further research should be conducted to examine the carbon insole effects on sports performance and long-term muscle activation and perceived feelings.

Myeonghoon Ko, Tiejun Ma, Shuping Xiong

Conference Proceedings

Intervention of arch support: A quantitative study

Hallux valgus is a common foot deformity characterized by hypermobility of the first metatarsal ray. The lower longitudinal arch is an intrinsic factor related to the lateral drift of the hallux. This paper conducted a quantitative study on the improvement of the first metatarsal and arch condition by arch support and used finite element analysis to simulate the bone displacement with the intervention of arch support. In this research, a foot arch support made of carbon fiber was developed and seventy-six female subjects were recruited for a two-month wear trial. Footprints of their dominant foot were measured to investigate the effect of the arch support on lifting the arch and correcting the hallux valgus pathology. Different foot parameters including foot length, foot breadth, heel breadth, arch angle, arch breadth, plantar arch index, foot type index, and hallux valgus angle were also compared. By using finite element analysis, the biomechanical effects of the arch support on the foot structure can be visualized. According to the results of the wear trial, the use of the arch support can significantly improve the arch curvature of the foot, while no significant correction of the hallux valgus angle was found. Among the arch parameters, the arch breadth and the foot type index are the key indicators to precisely characterize foot types and arch conditions. When a clear outline of the footprint is not available, arch breadth provides reliable association with the foot type index (R2 = 0.928). An arch breadth ≥ 4 cm is categorized as flatfoot. This article confirms the effectiveness of our arch support in lifting the arch over a two-month period and provides a scientific surrogate index to aid in diagnosis, which is important for therapeutic and diagnostic applications.

Mei Ying Kwan, Kit Lun Yick, Joanne Yip, Chi Yung Tse

Conference Proceedings

Cycling Stability and Symmetry using a Corrective Bib Short

In cycling, biomechanical posture optimization strives to improve core stability and symmetry in the lower and upper extremities to raise power output. In addition, the shape and pose of the cyclists determine the projected frontal area, which is the major factor influencing drag during cycling. In this study, a high-fidelity prototype garment was developed that includes kinetic bands and proprioceptive devices to adjust biomechanical posture during cycling. The aim is to measure improved projected frontal area, stability, and symmetry as a result of wearing a corrective cycling garment. Thirty participants were gathered under strict exclusion criteria to ensure a representative sample of the population. Two exploratory studies were conducted: experimental and reference measurements of 1) 11 cyclists’ pedal balance and projected frontal area, and 2) 5 cyclists’ biomechanical movements through an optical motion tracking system. The results indicate an improved pedal balance and deteriorated stability and symmetry for the corrective bib short.

Senne Henderieckx, Alexander Van Gastel, Jochen Vleugels, Sam Smets, Stijn Verwulgen

Conference Proceedings

Smart Detective Gloves (PROSAFE) for Reducing Carpal Tunnel Syndrome Injuries

Carpal Tunnel Syndrome is a common health issue that targets the Median Nerve in the Carpal Tunnel Area, causing severe damage that affects the health of the patient and the overall performance of the originations. In this project, we came up with a new innovative smart detective glove that would be able to reduce the effects of CTS using special types of sensors and other supporting tools. The glove is a customer need-driven product that has some important features including measuring and detecting bending angles of the hand, analyzing the hand postures, and warning the users, in addition to that it has to measure the amount of pressure applied to the Carpal Tunnel Area specifically to the Median Nerve. It is cost-effective, light in weight, environmentally friendly, adjustable, and an easy-to-use device. Our approach for designing the glove was the double diamond theory which consists of four main stages starting with discovering our goals and defining the main components of the design followed up with the development of the design concept and its working principle and delivering ourPROSAFE smart glove at the end. Cost Analysis was used to check the feasibility of the design and how effective it is in terms of cost-saving. This glove will be able to predict, follow up CTS progression, warn the users and suggest the best hand posture for specific repetitive work.

Saed Amer, Asmaa Alsereidi, Marwah Aldhanhani

Conference Proceedings

Comparing semiautomatic Rapid Upper Limb Assessments (RULA): Azure Kinect versus RGB-based machine vision algorithm

Correctly using a rapid upper limb assessment for working postures is crucial to avoid musculoskeletal disorders. Although motion capture technologies and in particular depth cameras are widely used, they cannot be used in large-scale industrial environments due to their high cost and their performance greatly impacted by the surrounding environment. We thus compared the effectiveness of a commercial machine vision algorithm (named ErgoEdge) based on an RGB camera against an application here developed based on the depth camera Microsoft Azure Kinect for the RULA evaluation (AzKRULA). We conducted an experiment where fifteen static postures were evaluated with Microsoft Azure Kinect and ErgoEdge, and the results were also compared with those of an expert in ergonomics. This experiment showed a substantial agreement between the solutions provided by the semi-automatic RULA evaluation and the ergonomic expert and between AzKRULA and ErgoEdge. At the same time, it showed that the RGB camera must be placed on the side of the worker due to the difficulties of the machine vision algorithm in reconstructing from a frontal view, important joint angles in 2D space (e.g., to evaluate the neck and trunk), which can invalidate the RULA evaluation provided by ErgoEdge. Moreover, the RULA evaluation with AzKRULA and ErgoEdge highlighted the need for an in-depth study into the thresholds of the secondary factors (i.e., all the factors for the RULA evaluation that are not computed from the thresholds of joint angles) as the highest differences between the two evaluations and the ergonomist one arises on them.

Antonio Maria Coruzzolo, Francesco Lolli, Nazareno Amicosante, Hrishikesh Kumar, Pramod Thupaki, Saurav Agarwal

Conference Proceedings

Prediction of Muscle Fatigue During Dynamic Exercises based on Surface Electromyography Signals Using Gaussian Classifier

Muscle fatigue is shown to be associated with incidence of musculoskeletal injuries found with sports training and competition. The real-time detection of fatigue onset allows preventative measures to be taken in time to minimize injuries. In this paper, we aim to provide a framework that classifies muscle fatigue based on surface electromyography (sEMG) features extracted during dynamic exercises. This includes the use of data segmentation, real-time-compatible data normalization, a principal component analysis (PCA) based feature reduction and Gaussian classifier methods.An experiment has been carried out to acquire the sEMG signals of the upper two pairs of rectus abdominis muscles of four healthy adult volunteers during weighted decline and bench-assisted sit-ups. The collected sEMG signals are then segmented into concentric and eccentric segments by using the inertial measurement unit (IMU) data. Eight commonly used sEMG features are extracted from each segment. We fit two Gaussian models (GMs) on the distribution of fatigued and non-fatigued data samples and show that the GM can utilize this information to predict the number of repetitions possible before task failure. We fit another set of GM on a reduced feature space by projecting the data onto principal component axes obtained through singular value decomposition (SVD). By projecting the features onto the first two principal axes, we achieve similar accuracy and f1-scores compared to the GM by using 6 handpicked features. This reduction in the feature space greatly reduces the training samples necessary for such class-imbalanced datasets. This classifier can also be directly used in the real-time detection of muscle fatigue during dynamic movements, which can be adopted in applications in sports, workplaces, and rehabilitation sciences. These frequency-time characteristics also provide insight into the function of low-level feature extractors when developing deep learning models to identify muscle fatigue.

Yeok Tatt Cheah, Ka Wing Frances Wan, Joanne Yip

Conference Proceedings

Integrating sEMG into NIOSH protocol: a manual material handling risk assessment in the fruit and vegetable department of a supermarket

The biomechanical risk of cashiers in the retail sector has been extensively studied in literature. Despite high back pain prevalence in this sector manual material handling (MMH), instead, seems almost ignored. The aim of our study is MMH risk assessment in a fruit and vegetable department of a supermarket. This task wasn't still investigated, to date, together with standardized protocols and instru-mental-based tools. The sizes of the shelf allowed the use of the NIOSH protocol for the low level, whereas middle and high did not allow its use due to horizontal distance that exceeded the 63 cm set by the protocol. To integrate the NIOSH pro-tocol was used surface electromyography (sEMG). The recommended weight limit (RWL) in our case, according through NIOSH liftinq equation, was 17 Kg. The maximum handled weight from the workers was 14 Kg. The maximum mean peak value while lifting 14 Kg at a low level was 40.1% of Maximum Voluntary Contraction (MVC) in the left Erector Spinae. We assumed this sEMG value to be a safety value and used as a limit for lifts at the middle and high shelf levels because the maximum handled weight of 14 Kg was lower than the 17 Kg limit calculated through the NIOSH equation for the low level. This sEMG limit was exceeded, in the middle, while lifting 14 Kg (47.8% MVC), and in the high level lifting 10 Kg (44.7% MVC), 12 Kg (50.3% MVC), and 14 Kg (57.7% MVC). Our findings show that, for the analyzed shelf and for the male working popula-tion of that supermarket, we could accept as reasonably safe handling boxes up to 14 Kg for the low level, up to 12 Kg in the middle, and up to 8 Kg in high. This study shows that the integration of different assessment tools, such sEMG and NIOSH protocol, could help to a better estimation of biomechanical risk assess-ment. The study, moreover, provided practical guidelines for the health and safety service concerning the recommended load handled on each shelf level to minimize the risk of MMH in the fruit and vegetable department.

Alessio Silvetti, Alberto Ranavolo, Giorgia Chini, Tiwana Varrecchia, Antonella Tatarelli, Lorenzo Fiori, Adriano Papale, Ari Fiorelli, Francesco Draicchio

Conference Proceedings

Anxiety level among industrial engineering students in virtual learning

Stress is one of the most important psychosocial risks and it can produce, among other things, different degrees of anxiety, in work life, in studies or in any field of activities carried out by human beings. Anxiety is a state of mind and a physiological response of the person when facing a situation that causes anguish, fear and mental and emotional blockage. Among young university students, this occurs to a greater or lesser degree and is often not diagnosed or evaluated in its true magnitude. The Covid 19 pandemic has generated a radical change in the teaching modality that has gone to a virtual learning, which has aggravated the usual anxiety levels in students. The aim of this study was to examine the anxiety level of industrial engineering students of different academic levels, in this pandemic environment, to help them cope with this problem. To do this, a study sample was taken and an evaluation instrument was applied that allowed these levels to be established. Relationships were established with the number of credits taken on average and the study cycle of the students in the sample. The results show significant information that can help academic leaders and students themselves to take measures that help improve their anxiety levels.

Cesar Corrales, Jonatan Rojas, Wilmer Atoche

Conference Proceedings

Promoting Physical Wellbeing in the Workplace: Providing Working Adults with a Tool to Reduce their Sedentary Behavior

Whether it is from the office-office or the home office, creating a physical work environment is essential for both improving work performance as well as for the physical and mental wellbeing of employees. But as jobs are becoming increasingly less active, and working adults are spending almost a third of their lives in the office, most of their time is now spent sitting behind a desk. This time in sedentary behavior is increasing rapidly on a global scale and has become a great area of concern, as research has proven that this behavior is linked to an increase in all-cause mortality. To reduce the sedentary nature of the workplace, many companies are now replacing the standard desk with sit-stand desks (SSDs). SSDs are height adjustable desks that allow the user to work in either a sitting position or a standing position. Unfortunately, even as more companies are implementing these desks in their workspace, many studies indicate that there is a lack of utilization among working adults, with many only transitioning the desks to a standing position once a month or less.This paper presents a user-centered design project examining how to reduce the long-term sedentary behavior of desk-based working adults by motivating them to utilize their SSDs to make more transitions between sitting and standing. The project involved an agile design approach based on a cyclic process where a range of design techniques and research methods were used to look deeper into the practices and habits of working adults and better understand why this lack of use occurs and how it can be changed. These design techniques and research methods include a literature study, auto-ethnographical research, and 11 interviews with both active and non-active SSD users. An analysis of the differences between active and non-active users,led to the hypothesis that to reduce the SB of desk-based working adults, the use of SSDs in the workplace should be normalized by ensuring that working adults understand the benefits and proper use of SSDs while also offering the key tools: (1) reminders of when to transiting between sitting & standing; (2) social support; (3) awareness of effects on body & mind ; (4) task-based transitions. . This hypothesis was then used to initiate an empirical research through design process. Through this process, the final concept, BMDesk Application and Controller, was created. The BMDesk showcases an interactive digital platform and controller which utilizes the previously defined design opportunities to aid desk-based working adults in becoming more in tune with their physical and mental state while also providing them with the support they need to reduce their long-term sedentary behavior by utilizing their SSDs. The platform provides the user with an interactive tool that (1) gives them control over setting up their workday and defining how many sit-stand transitions they want to make and how long they want to remain in each position; (2) triggers a light reminder indicating to the user when it is time to check in and (3) provides a step-by-step body and mind self-evaluation included in the digital application; (4) based on the self-evaluation, the application provides a personalized tip and option to “learn more” about how the user can alter their position to relieve them of any physical or mental pain they are experiencing; (5) allows the user to choose if they actually want to change position and provides an additional reminder after a preset amount of time in the case they do not switch; (6) uses a two-way LED infrared sensor to automatically track the number of transitions and how long the user is in each position; and (7) allows the user to connect with the coworkers or friends to setup challenges or select times to standup together.

Michal Adar, Renate De Bruin, David Keyson

Conference Proceedings

Assessment of risk factors of upper-limb musculoskeletal disorders in a fish processing industry

A large number of studies show that awkward postures and repetitive hand and wrist movements contribute to the development of work-related musculoskeletal disorders (WMSDs). To effectively prevent these problems, there is a need for precise and quantitative knowledge about the relation between exposure and effect. In most epidemiological studies of disorders of the upper limbs, information about exposure is too limited or imprecise. Moreover, the exposure often involves several dimensions, and therefore it is necessary to use reliable methods to obtain trustworthy risk estimates. Therefore, the aim of this study was to evaluate the risks in relation to repetitive movements of the upper limbs of workers, as well as analyze the effects of a reduced work pace on the risk levels in a fish processing industry. The study was conducted in a Brazilian fish processing industry with 1,900 workers, who were divided into two work shifts. The OCRA checklist was used to assess 10% of the total workforce during work tasks. The 13 main work tasks (homogeneous groups) of the productive sector were analyzed. The occupational repetitive actions performed by workers were 81.5 ± 19.2 per minute, representing 10 points on the OCRA scale (0 to 10 point scale). The average score of the OCRA checklist was 18.4 ± 2.9 (moderate risk). Considering the five risk categories proposed by the OCRA method, 12 tasks were deemed moderate risk (92%) and 1 low risk level (8%). Due to the predominance of the highly repetitive movements of the upper limbs in fish processing work, and previous studies suggesting a reduced work pace to prevent UL-WMSDs, simulations of a pace with very low risk levels were carried out utilizing the OCRA checklist. By conducting these simulated interventions, it was possible to reduce the risk of UL-WMSDs to very low levels in all tasks by only decreasing the work pace (-42.8 ± 17.7%). These results suggest that most of the tasks carried out by workers were classified as moderate risk, predisposing workers to a greater probability of developing UL-WMSDs (10.8 to 21.5%) than the population that was not exposed. Simulations of a reduced work pace showed the effectiveness of this organizational measure in lowering the risk of UL-WMSDs.

Diogo Cunha Dos Reis, Antônio Renato Pereira Moro

Conference Proceedings

Effect of Different Intervention Methods on Recovery of Exercise-Induced Muscle Fatigue

The aim of this study is to study the effects and differences of different recovery methods such as passive break (PB), active break (AB), and vibration break (VB) on muscle performance recovery after muscle fatigue. The biceps brachii (BBM), which is prone to fatigue during exercise, was taken as the object to study. 10 healthy males were recruited to conduct the experiment. After the experiment, One-Way Repeated Measures ANOVA was used to compare the difference of muscle performance index (MVC, RMS, MF) between groups (PB, AB, VB) at different time points (pre-fatigue, post-fatigue, and post-recovery). JASA method was also used to analyze the muscle recovery effect. Results show 1-minute AB is more effective for muscle fatigue recovery between exercise sets than 1-minute VB after effects.

Yiyang Chen, Zhanxun Dong, Zhang Xingqiang

Conference Proceedings

Physical, Psychophysical and Demographic Changes Require Automated & Autonomous Machines & Equipment (AAM&E) in Construction

Construction is one of the most dangerous with high prevalence of work-related fatalities and injuries among the high-risk industrial sectors. Concurrently, the construction industry is experiencing workforce demographic changes and shortages of skilled trade/construction workers. This paper provides an overview of the shifting construction workforce and the benefits & exposures from the evolving automated and autonomous machines & equipment (AAM&E) under development for the construction industry. Specifically, this paper describes a synopsis of design methodology and principles of AAM&E associated with human-related factors (e.g., self-efficacy, mental/cognitive workload, situation awareness). Also, this paper discusses potential practical applications and insights on the human-machine interaction/collaboration and key factors for building trust in human-robot teamwork (e.g., rule-based framework, transparency/feedback, observation, predictability). This paper can assist human factors & ergonomics (HFE) and safety professionals who may not be current with this evolving AAM&E technology to pre-plan and design control methods into industrial and construction projects.

Sang Choi, James G Borchardt

Conference Proceedings

Psychological conditions for the development of stress resistance in specialists of different age categories

The article identifies the psychological conditions of development of social workers of different ages. The peculiarities of the development of stress resistance of social workers of different age groups, its structural components have been empirically studied and their relationship with psychological conditions has been established. The effectiveness of the development program of activating the psychological conditions for the development of stress tolerance of social workers of different ages has been experimentally tested.

Oksana Kravchenko, Marina Mishchenko, Olena Soroka, Yulia Teptiuk, Oleksandr Safin, Olena Andrusyk, Oleksandr Timchenko, Vitalii Khrystenko

Conference Proceedings

The effects of flash frequency and amount of information in mitigating the effects of fatigue

Fatigue is a crucial factor related to aviation safety and is likely to result in negative impacts in cockpit operation tasks, especially for warning information recognition in emergency situations. The aim of this study was to examine the effects of sleep deprivation induced fatigue on task performance of warning recognition tasks, and how the above effects were moderated by two presentation characteristics of warning information (i.e., flash frequency and amount of information). Nine participants participated in an experiment in which they performed warning recognition tasks under both normal and fatigue conditions. Fatigue condition was induced by one night of sleep deprivation. Flash frequency ranged from 1 to 5 HZ in increments of 1 HZ, while amount of information was indicated by the number of information elements and ranged from 3 to 5. The results indicated that sleep deprivation induced fatigue and overload information amount impaired performance significantly, while flash frequency yielded no significant effect on human performance in fatigue condition. Besides, fatigue interacted with amount of information. Interestingly, in fatigue condition when the information amount raised up to 5, the response time significantly decreased by 100ms compared with 4, while in normal condition the response time increased with the information amount increasing. The findings suggested that fatigue and overload information amount are risk factors of aviation safety, and flash frequency has no mitigating effect under fatigue condition.

Xiaoyan Zhang, Hongjun Xue

Conference Proceedings

Integrating Ergonomics, Biomechanics, and Driving Behavior in a Virtual Environment: Developing a Transactional Framework

The World Health Organization identifies road traffic injuries are a global health problem. The Global Status Report on Road Safety 2015 (2015) reported that Urgent action is needed to deal with this health epidemic. This is significant because, it is predicted that without addressing this issue head-on, traffic crashes are predicted to become the seventh leading cause of death by 2030. the Sustainable Development Agenda 2030 proposed to reduce the global deaths and injuries occurring from road traffic crashes to half by 2030 (WHO). It in acknowledged that major cause of traffic accidents is a human error related to bad driving behavior or fatigue and drowsiness. Hence, the human factor in transportation design should be a great concern to many transportation researchers (Sanjaya and Sya’bana, 2017). Although human factors have been analyzed through assessment of speed, driving behavior, reaction time, and overall cognitive assessment of environment, transportation research in general has neglected ergonomic study of humans in general (Sanjaya and Sya’bana, 2017) and in particular to understand road traffic crashes. Motion analysis is related to one branch of biomechanics called kinematics, which is the accurate measurement of human motion geometry (Knudson, 2007). Virtual Reality (VR) devices offer the natural solution for inexpensive and compact driving simulation, maintaining a high degree of the immersion feeling.Several studies have evaluated the physiological response to driving using a driving simulator, including measures such as HR variability (HRV), EDA, electromyography (EMG) of the anterior tibialis or trapezius muscle and electroencephalography (EEG). Several driving conditions contribute to differences in signals such as braking, mental workload or physical fatigue (Eudavea and Valencia, 2017). Vehicle operators must rapidly assess changes in vehicle stability and adjust body position in order to maintain vehicle control as they negotiate various road networks and types. Simulation can safely replicate changes in vehicle center of mass, and the operator’s biomechanical responses to these changes can be measured (Jennison et al 2017). However, studies related to human factors and driving have either analyzed the likelihood of traffic injuries (Petridou and Moustaki, 2001) or analyzed the physiological responses to driving behavior independently such as eye tracking (Kasneci, E., et al 2017), ECG and EMG (Eudavea and Valencia, 2017); and postural markers (Jennissen, et al 2017). A comprehensive framework to analyze the driving behavior in virtual simulator and assessing its impact on human physics remains a gap to the best of our knowledge.This research therefore investigates human impact and impact on humans of driving behavior using virtual reality. This study develops a theoretical framework to comprehensively assess the personal, situational and environmental factors that impacts driving behavior and its integration within virtual environment. It furthers this integration by developing a normative framework that uses biomedical and physiological approaches to investigate the impact of driving behavior on human body. Development of such a comprehensive framework will help further the knowledge and understanding of driving safety and human ergonomics and guide further research in this field.

Praveen Maghelal

Conference Proceedings

Introduction of Distractions in Immersive Virtual Reality Laparoscopic Surgery Training – a Pilot Study

Reducing human errors by surgeons is of great importance to patient safety. The main drawback of current VR laparoscopic surgery training is that it only focuses on improving the proficiency of basic surgical skills while lacking the true representation of the busy and chaotic OR surroundings. Multiple distractions were introduced into this study to explore the influence on the laparoscopic surgery training process. A VR headset displayed a video of a laparoscopy procedure recorded by a 360° camera in a real OR, which contains various distractions occurring during the surgery. Ten surgical trainees performed a standardized training task in the virtual OR under both non-distractive and distractive conditions. Questionnaires, videos and semi-structured interviews were used to collect data. The results showed that the introduction of distractions significantly reduced participants' task performance (p<0.001) and increased their mental workload (p=0.001). Participants also showed different degrees of sensitivity to various distractions. In addition, most participants raised the need for system personalization. This VR-based immersive virtual OR demonstrated its potential to enhance surgeons' ability to deal with distractions in laparoscopic training. Future work will focus on improving the personalization and interactivity of the system, thereby increasing the training efficiency.Keywords: Immersive virtual reality; Surgical training; Distractions; Human error; Cognitive Workload

Xintong Wu, Tianren Luo, Shuping Xiong, Yuanyuan Liu, Meng Li

Conference Proceedings

Understanding the Impact of Induced Stress on Team Coordination Strategy in Multi-user Environments.

Managing air traffic control, medical emergencies and multi-robot systems are prime cases where human teams have to work on complex tasks. In such cases, these teams are continuously working under stress induced by instability, complexity and time pressure. The success of such teams is primarily driven by effective team coordination. The objective of this study is to understand the impact of induced stress on human team coordination strategy. In this study, two online tasks were designed to induce stress in participants, one in single-user and the other in multi-user collaborative environments, measuring individual and collaborative teamwork performances respectively. Both experiments were conducted under induced time pressure and auditory distraction. Our analysis showed that team members prefer to switch between different strategies and thus, the coordination shifts from explicit to implicit coordination. However, in the single-user environment, the participant's performance was influenced by their competitor's performance, regardless of the participant's abilities. Future research will determine how these effects interact with physiological signals.

Lokesh Singh, Sarvapali Ramchurn, Obaid Malik, Jediah Clark

Conference Proceedings

Impact of remote work on ergonomic risk in Peruvian companies during COVID-19

The COVID-19 pandemic has forced to most organizations to implement remote work as a viable option to continue working. Worldwide this is the normal current situation, and Peru has not been the exception to this issue. However, the lack of adequate readiness to manage this working modality has resulted in the appearance of musculoskeletal discomfort. The prevalence and severity of this health condition increase as more time has passed since the onset of this situation. This readiness includes both, having adequate space and furniture at home, as well as having healthy posture and habits.In this study we will analyze the impact that remote work has had on people's ergonomics and how different factors influence it. We will also present some proposed actions to adapt the remote workplace to reduce the incidence on this health condition, under de understanding that this situation will continue as part of the new normal for most organizations.

Wilmer Atoche, Jorge Wam, Akio Murakami, Percy Mesias

Conference Proceedings

The Influence of Lifting Horizontal Distance Measurement Error on NIOSH Lifting Equation Assessment Outcomes

Low back injuries are becoming increasingly costly due to the compensation costs and lost days of work. Most of these injuries are linked to manual material handling (MMH) activities. Several ergonomic assessment methods are available to assess the risk factors and determine the risk level for a given MMH job. The National Institute for Occupational Safety and Health (NIOSH) Lifting Equation is the most popular and frequently used ergonomic assessment method to assess MMH jobs. The load weight and horizontal distance are the most significant low back pain risk factors in such jobs. Errors in the measurements of load horizontal distance may influence the risk level obtained from the NIOSH Lifting Equation assessment method depending on the weight of the load being handled. Measurements of the horizontal distance variable measured by novice college students were used to examine NIOSH Lifting Equation sensitivity to the horizontal distance measurement errors with respect to the load weight. The results showed that even though errors in the horizontal distance measurements influenced the resulted lifting index values, that did not influence the resulting NIOSH Lifting Equation risk assessment outcomes for almost all lifting conditions.

Khaled Hafez

Conference Proceedings

Ergonomic parameters considering physical workload for optimization models in manual order picking

Order picking is a crucial contributor to corporate success within the value chain of companies. However, due to the high proportion of manual work, there is a risk of employees developing musculoskeletal disorders. In order to reduce this risk, it is vital to take ergonomics in planning concepts for order picking into account. For this purpose, ergonomic parameters are derived for picking from shelves and pallets in this paper on the basis of the EAWS screening method. The results are supported by data on postures and working conditions from practical surveys in four companies. The ergonomic parameters can subsequently be used in optimization models for order picking.

Tim Steinebach, Jurij Wakula, Heiko Diefenbach, Christoph Glock, Eric Grosse

Conference Proceedings

Plantar Soft Tissue Stiffness Automatic Estimation in Ultrasound Imaging using Deep learning

Preventing diabetic foot ulcers (DFU) is critical for diabetes mellitus (DM) patients. Increased stiffness of plantar foot may cause higher plantar pressure leading to a higher risk of DFU. Soft tissue stiffness can be determined by measuring the soft tissue thickness with indentation depth and stress. Therefore, we hypothesized that the deep learning model could detect the ultrasound image pixel change under soft tissue compression. This study aimed to apply the deep learning model to analyze the ultrasound image pixel thickness of plantar foot, then predict the soft tissue indentation depth and loading force for estimating the stiffness. This study has developed a motor-driven ultrasound indentation system to apply programmable compression and simultaneously assess soft tissue mechanical properties and responses in indentation depth and loading force. In addition, the effective Young's modulus was calculated to characterize mechanical properties of soft tissues in the first metatarsal head. The deep learning method employed the YOLOv5x model to train and detect the small object in the indentation depth, such as ultrasound image pixel changes. Finally, the dataset images were processed with labeling annotation from the soft tissue indentation depth and loading force. The deep learning results showed 0.995 in mean Average Precision (mAP), 0.999 in precision, 1.000 in Recall, and 0.013 in Loss. A significant correlation was found between the ultrasound image pixel changes and soft tissue indentation depth (r = 0.98, p < 0.05). Furthermore, a significant correlation was observed between the ultrasound image pixel changes and the loading force in the first metatarsal head (r = 0.85, p < 0.05). The validation and prediction models were lower than the training models in the effective Young's modulus results. However, the results of the initial modulus were similar between the three models. Our findings recommend that applying deep learning in the ultrasound image can predict soft tissue indentation depth and loading force to calculate the stiffness of the plantar foot.

Yori Pusparani, Ben-Yi Liau, Yih-Kuen Jan, Hsu-Tang Cheng, Peter Ardhianto, Fityanul Akhyar, Chi-Wen Lung, Chih-Yang Lin

Conference Proceedings

The physical load of the Human body during Motion with BP Neural Network

Background: Unreasonable tasks will increase the person’s physical load, leading to safety accidents and occupational diseases. To ensure a reasonable physical load and improve the operational efficiency of the person as far as possible, it is necessary to predict and evaluate the physical load of workers in real-time.Objective: A prediction model of the physical load intensity of the human body based on a neural network was established, and its effectiveness was verified.Methods: Twelve volunteers completed four movements walking, jogging, climbing, and jumping. The surface electromyography (sEMG) on the left and right sides of the rectus femoris and biceps femoris was measured, and the motor posture of volunteers was obtained by Vicon, the joint torque, maximum muscle activity, and muscular force parameters were calculated based on the reverse dynamic model of human motion. The sEMG eigenvalue and mechanical load parameters in different postures were considered input and output, respectively, and 80% of all data were used as the training set and the rest as the validation set.Results: In this study, we found that the hip joint, knee joint, and ankle joint have a sizeable joint torque during movement, in which the joint torque of the ankle joint is the largest and twice human body weight at its peak. Besides, a larger muscle load occurs at the beginning and end of contact between the human foot and the ground, and the muscle strength of the rectus femoris was significantly higher than that of the biceps femoris (p<0.05). The number of neurons in the input layer, an output layer, and a hidden layer of the model is 32, 13, and 12, respectively. This study found that the prediction error of maximum muscle activity was 6.4%. The average prediction error of joint torque was 8.7%, and the prediction error of the muscular force of the rectus femoris muscle was no more than 9.5%. This model can reasonably predict the physical load of the human body.Conclusions: A workload evaluation model based on the BP neural network was established in this research, which can analyze the biomechanics of the human body in motion and judge the human body’s physical load effectively according to the EMG signal.Application: This model can measure the body load of soldiers and firefighters in real-time during task training and provide a reference for task design.

Biyun Zhou, Xue Lihao, Xiaopeng Liu, Qing Yang, Liangsheng Ma, Li Ding

Conference Proceedings

Modeling of changes in lumbar joint stiffness by pelvic tightening based on physique and pelvic alignment

We have been elucidated the mechanism by which pelvic belt reduces lumbar burden. Pelvic tightening increases the lumbar joint stiffness and inhibits the flexion of the lumbar spine in the forward bending. Flexion of the lumbar joint is substituted by the hip joint, which corrects the posture during forward bending and reduces the lumbar burden (lumbar joint torque). The level of the assisting effect of the tightening force has the individual difference, but at present, it is not clear what factors cause it. In this study, we develop a model that represents the assistance effect based on the physique such as height and weight, and the posture and shape of the pelvis and lumbar spine (pelvic alignment).This study developed a regression model that expresses the amount of change in joint stiffness due to tightening force, using the individual physique and pelvic alignment characteristics as input. The joint stiffness was estimated from motion measurement using optical motion capture and obtained from the equation of motion of the link model representing the human body. Pelvic alignment was measured by X-ray images, and five features were obtained: sacral inclination angle (SS angle), pelvic inclination angle (PT angle), inclination angle of the sacrum relative to the pelvis (PI angle), curvature of the lumbar lordosis, and pelvic aperture angle. Among these, the SS angle, PT angle, and PI angle were measured under two conditions: standing and 45 degrees forward bending and obtained a total of eight pelvic alignment features. In addition, height, weight, BMI, and back muscle strength were added as physique characteristics expressing body size and muscle strength, for a total of 12 variable measured. These features were measured on 15 subjects. Among the 12 features, three to four variables were input to the model by excluding those that were strongly correlated with each other and less capable of explaining changes in the target value, joint stiffness.From the proposed model, changes in joint stiffness could be estimated from pelvic alignment and physique characteristics. At large forward bending angles, we found that to obtain a high assistance effect, tilting of the sacrum anteriorly relative to the pelvis and forward tilting of pelvis is necessary. On the other hand, in the mild forward bending, the person who is higher body weight in addition to the forward tilt of the PT and PI angles tend to obtain higher assistive effect.

Michihiro Yoshida, Tanaka Takayuki, Yoshio Tsuchiya

Conference Proceedings

Developing a computer-vision model to estimate anatomical joint coordinates during manual lifting tasks

This study developed a Computer-Vision based anatomical joint coordinates estimation model to predict the 3D joint coordinates with the help of Artificial Intelligence image recognition technology during manual lifting tasks based on single camera video inputs. The workflow of the proposed Computer-Vision model includes 2D joint detection and 3D joint reconstruction. The 3D joint error is calculated based on the Euclidean distance between the predicted 3D joint coordinates from the CV-based method and the corresponding joint coordinates of the ground truth from the Visual 3D TM skeletal model. The results indicated that the floor to shoulder lifting height path induced a greater 3D joint error than the floor to knuckle and knuckle to shoulder lifting height paths (p-value = 0.01). The 3D joint error of the hand was the largest than the other estimated joints. This study verified that the proposed Computer-Vision model could predict 3D joint points. Therefore, while the marker-based motion tracking system is inapplicable, the model can be used as an alternative solution for predicting lifting motion.

Chih-Yu Hsiao, Chien-Chi Chang, Ting-Yu Chen, Yi-Ting Lin

Conference Proceedings

Posture Analysis of Mass Rapid Transit (MRT) Passengers Using the REBA Method in Jakarta, Indonesia

Transit-oriented development (TOD) is one of the sustainable urban development concepts in tackling congestion, environmental degradation, and energy efficiency. To realise transit-oriented development, the government issued a transit-oriented development policy at every rapid mass transit (MRT) station in DKI Jakarta. The Mass Rapid Transit train (MRT) Jakarta has dimensions of 20 meters long, 2.9 meters wide and 3.9 meters high. Dominated by metallic blue and grey, the train body is made of stainless steel with an empty weight per train reaching 31 to 35 tons. PT MRT Jakarta provides 16 train series (one series consists of six trains) so that the carrying capacity of one series reaches 1,950 people per series. The train’s interior is equipped with air conditioning, two CCTVs, hand straps, priority seats and a particular wheelchair area. Seats are made of fibre reinforced plastic (FRP) which is fire resistant with a width of 43 cm x 42 cm. This study aims to analyse the passenger posture by the Reba method with the results of measurements obtained in section a, namely 6, section b is 5, and the meeting point between parts a and b is 8. That is, the results of the Reba score have a high level of risk with immediate action needed. From the results of calculations, it is found that the sitting position of the MRT passenger is not ergonomic. Therefore, the authors analysed the posture of the passengers of the Jakarta MRT passenger with the Reba method to provide suggestions for improving posture and seats.

Dessy Laksyana Utami, Aisy Luthfianisa Putri

Conference Proceedings

Changes in Lactate After the Completion of Repetitive Cycle Exercises with and without Compression Arm Sleeves

Occupational compression sleeves are commonly used to relieve pain in the upper and lower extremities. Anecdotal data agree on the benefits of using compression sleeves while performing physical work. The purpose of this study was to assess the effects of wearing compression sleeves on the upper limbs on blood lactate concentration while completing a physically demanding activity. This study included six college-age participants from the University of Texas at El Paso. Anthropometric measurements were taken before the beginning of the study. Afterward, each participant’s basal capillary blood lactate level was established by averaging lactate concentration from three consecutive days. Capillary blood samples were taken from the participant’s earlobe, and lactate concentration (mmol/L) was assessed using the Lactate Plus Lactate Analyzer (Nova Biomedical). After obtaining all the baseline measurements, each participant completed six simulated work sessions, one with sleeves and another without sleeves, at an intensity of 25 Watts, 50 Watts, and 75 Watts a cadence of 60 RPM, and 10 minutes of duration. All participants rested for at least 72 hours between sessions to prevent muscular fatigue effects of lactate concentrations. The use of compression sleeves showed an average reduction of lactate concentration of 0.2 mmol/L. This study shows the potential benefits of wearing compression sleeves while performing activities involving the upper limbs by helping prevent lactate accumulation, a common indicator of muscular effort.

Amber Rohrer, Daniel Conde, Samuel Montalvo, Manuel Gomez, Jennica Juarez, Gabriel Ibarra-Mejia

Conference Proceedings

Musculoskeletal Risk Level among Health Professionals of a Health Entity

The level of musculoskeletal risk in upper limbs was determined in five areas where health professionals of a health entity in Bogotá-Colombia practice. The essential duties in the Medicine, Bacteriology, Dentistry, Physiotherapy, and Nursing spaces were selected through interviews with employees; the RULA approach was then used to establish the most critical components and the final score. At the level of the neck, shoulders, and wrists, forced postures were the variable that increased the score in areas such as dentistry, Bacteriology, and Physiotherapy. In almost all areas, load handling and movements with high frequency were evidenced. The above findings guide the improvement actions, and the consideration of other factors to be reviewed is recommended.

Wilder Hernández, Sandra Bibiana Avendaño Avendaño, Luis Gabriel Gutierrez

Conference Proceedings

The impact of double gloves on hands temperature and blood volume changes at low temperature: A Case Study

A young, healthy man wore the selected protective clothing and double gloves, which met the requirements of EN 511 standard. The selected manual tasks (e.g., Valpar Component Work Samples 1 - VCWS 1 Small Tools (Mechanical) (Bases of Virginia, LLC, USA)) were performed in a climatic chamber at low temperature (-1 degrees Celsius; 30.2 degrees Fahrenheit).Before entering and after exiting the chamber, changes in finger temperature and blood volume were determined using an infrared thermographic camera and plethysmograph. A decrease in both finger and hand temperature was observed after exposure to cold. In conclusion, the impact of low environment temperature (1h exposure) on the reduction of finger and hand skin temperature was significant. Even properly selected protective gloves, allowing for simultaneous performance of manual tasks, did not prevent the decline in hand and finger temperature. The low environment temperature (1h exposure) has a negative effect on hand and finger skin temperature, despite the use of appropriately selected protective gloves.

Magdalena Młynarczyk, Joanna Orysiak, Emilia Irzmańska, Piotr Prus, Elżbieta Łastowiecka-Moras

Conference Proceedings