Ergonomic Design and Assessment of an Adjustable Laptop Stand Used in the Typing Task.

Background: Laptops are ubiquitous tools in today's society; however, their prolonged use often leads to discomfort and musculoskeletal disorders due to their nonergonomic design. This study aimed to evaluate the effectiveness of an innovative adjustable laptop stand in enhancing comfort and productivity during typing tasks. Methods: A 2-phase experimental design was employed. Phase 1 involved the development of a novel laptop stand considering ergonomic principles and expert recommendations. In Phase 2, a total of 25 office workers-13 men and 12 women-participated in 3 randomized sessions of a 2-hour typing task. They used the newly designed stand, adjusted their laptop height using conventional methods, or completed the task without any height adjustment (control). The Local Subjective Discomfort Questionnaire (LPD), the Rapid Upper Limb Assessment (RULA), and speed and error rates were used to measure postural risk, subjective discomfort, and typing performance, respectively, during each session. SPSS Version 26 (IBM) was used for the analysis, and P ˂ 0.05 was considered statistically significant. Results: The RULA scores were significantly lower with the newly designed stand compared with the other conditions. When using the stand, perceived discomfort in specific regions significantly decreased (P < 0.05). Moreover, the number of typing errors significantly reduced with the stand (P < 0.05), while no significant difference was observed in typing speed (P = 0.371). Conclusion: The novel adjustable laptop stand significantly reduced discomfort and improved typing accuracy during typing tasks, suggesting its potential to enhance user comfort and productivity. However, further longitudinal studies are needed to assess the long-term effects of this intervention.

Effects of variations in the tragus expansion angle on physical comfort for in-ear wearables.

Tragus expansion angle (TEA) is an angular variable that quantifies the outward degree of expansion of the tragus cartilage induced by in-ear wearables (designed with hard materials) fitted into the external ear. It is a physical factor that directly influence user's comfort experience during interaction with in-ear wearables. This study was aimed at quantifying the effects of variations in TEA on physical comfort. TEA was measured and normalised employing a measuring device and Tragus Expansion Index (TEI) proposed in this study. Physical (dis)comfort was assessed using a rating scale designed based on the 5-point Likert and Borg-CR10 scales. Comparatively, the comfort range of variations in TEA was similar for both genders. Males could endure a higher level of variations in TEA compared to females. A quantitative relationship between variations in TEA and (dis)comfort ratings was established using TEI values and GaussAmp function, which can be employed for ergonomic design purposes. Practitioner summary: This study provides an empirical and available source for quantifying the effects of variations in the tragus expansion angle on physical comfort, including quantitative tools and (dis)comfort rating models, which could be used as a reference for improving the fit, comfort and functional capacity of in-ear wearable devices.

Laparoscopic instrument for female surgeons: an innovative model for endoscopic purse-string suture.

Commercially available laparoscopic instruments are not designed for female surgeons. We redesigned the endoscopic flexible head purse-string suture instrument for improved use by female surgeons. The weight, total length, and diameter of the swing head handle and clump handle were reduced (786 to 565 g, 715 to 700 mm, 70 to 50 mm, and 30 to 25 mm, respectively). Stroke of the slide for firing and release of the lever was reduced from 92 to 83 mm. This is the first step toward an ergonomic surgical device that considers physical differences related to sex.

Analysis of the external acoustic meatus for ergonomic design: part I - measurement of the external acoustic meatus using casting, scanning and rapid estimation approaches.

Numerous ear-related wearables require precise measurements of the external acoustic meatus (EAM) to optimise function and comfort. The purpose of this study is to describe a novel methodology for measuring the EAM. A total of 23 measurement variables (18 novel) of the EAM from the entrance to the second bend were collected on 700 Chinese subjects (age: 15-83) using casting and 3D scanning over seven age spans: 10, 20, 30, 40, 50, 60 s and 70+. The ear horizontal plane was identified as a new reference plane for measurements and the medial concha was selected as the reference point for positioning the entrance. A detailed approach to characterising the EAM was developed as was an approach for the rapid estimation of circumference and area using regression equations making it ideal for use in early design conceptualizations. Practitioner summary: This study provides a scalable measurement methodology for determining anthropometric measurements of the external acoustic meatus. The measurement methodology and its application to the design and fitting of ear-related wearables are important to optimising their function and comfort.

Analysis of the external acoustic meatus for ergonomic design: part II - anthropometric variations of the external acoustic meatus by sex, age and side in Chinese population.

For devices worn inside the ear, detailed anthropometric data of the external acoustic meatus (EAM) is needed, yet lacking due to the complex and costly methodology associated with attaining such measurements. The purpose of this study was to provide the anthropometric characteristics of the EAM including variations by age group, sex, and side (right/left). 1400 external ears (700 Chinese subjects) were casted and scanned. A total of 23 EAM dimensions of length, width, angle, circumference and area were measured, most of which changed by age group, sex and side. 19 measurements were larger in males and 17 measurements were larger in left-side ears. Except the entrance length and circumference, measurements were not statistically significant between left- and right-side ears. This study provides key anthropometric measurements of the EAM in a Chinese population which can be used for ergonomic design purposes. Practitioner summary: This study provides an available source for anthropometric variations of the external acoustic meatus by age, gender and side in the Chinese population, which can be used as a reference to improve the fit, comfort and function of in-ear wearable devices.

The handaxe reconsidered.

The Acheulean handaxe is one of the longest-known and longest-surviving artifacts of the Palaeolithic and, despite its experimentally tested functionality, is often regarded as puzzling. It is unnecessary to invoke a unique-for-mammals genetic mechanism to explain the handaxe phenomenon. Instead, we propose that two nongenetic processes are sufficient. The first is a set of ergonomic design principles linked to the production of sturdy, hand-held cutting tools in the context of a knapped-stone technology that lacked hafting. The second is an esthetic preference for regular forms with gradual curves and pleasing proportions. Neither process is a cultural meme but, operating together in a cultural context, they can account for all of the supposedly puzzling time-space patterns presented by handaxes.

Biomechanical investigation of prolonged driving in an ergonomically designed truck seat prototype.

A postural evaluation during a prolonged driving task was conducted to determine the ergonomic validity of a new freely adjustable truck seat prototype. Twenty participants were recruited to perform two 2-h simulated driving sessions. Postures were assessed using motion capture, accelerometers and pressure pads. Subjective discomfort was also monitored in 15-min increments using ratings of perceived discomfort (RPD) and the Automotive Seating Discomfort Questionnaire. Participants had a more neutral spine posture during the first hour of the drive and reported lower RPDs while sitting in the prototype. Pairing the gluteal backrest panel with the adjustable seat pan helped reduce the average sitting pressure. The industry-standard truck seat may lead to the development of poor whole body posture, and the proposed ergonomic redesign of a new truck seat helped improve sitting posture and reduce perceived discomfort. Practitioner Summary: A new freely adjustable truck seat prototype was compared to an Industry standard seat to assess hypothesised improvements to sitting posture and discomfort for long haul driving. It was found that the adjustable panels in the prototype helped promote spine posture, reduce sitting pressure and improved discomfort ratings.

Glasses-type wearable computer displays: usability considerations examined with a 3D glasses case study.

This study presents usability considerations and solutions for the design of glasses-type wearable computer displays and examines their effectiveness in a case study. Design countermeasures were investigated by a four-step design process: (1) preliminary design analysis; (2) design idea generation; (3) final design selection; and (4) virtual fitting trial. Three design interventions were devised from the design process: (1) weight balance to reduce pressure concentrated on the nose, (2) compliant temples to accommodate diverse head sizes and (3) a hanger mechanism to help spectacle users hang their wearable display on their eye glasses. To investigate their effectiveness, in the case study, the novel 3D glasses adopting the three interventions were compared with two existing 3D glasses in terms of neck muscle fatigue and subjective discomfort rating. While neck muscle fatigue was not significantly different among the three glasses (p = 0.467), the novel glasses had significantly smaller discomfort ratings (p = 0.009). Relevance to Industry: A four-step design process identified usability considerations and solutions for the design of glasses-type wearable computer displays. A novel 3D glasses was proposed through the process and its effectiveness was validated. The results identify design considerations and opportunities relevant to the emerging wearable display industry.

Discomfort Evaluation of Truck Ingress/Egress Motions Based on Biomechanical Analysis.

This paper presents a quantitative discomfort evaluation method based on biomechanical analysis results for human body movement, as well as its application to an assessment of the discomfort for truck ingress and egress. In this study, the motions of a human subject entering and exiting truck cabins with different types, numbers, and heights of footsteps were first measured using an optical motion capture system and load sensors. Next, the maximum voluntary contraction (MVC) ratios of the muscles were calculated through a biomechanical analysis of the musculoskeletal human model for the captured motion. Finally, the objective discomfort was evaluated using the proposed discomfort model based on the MVC ratios. To validate this new discomfort assessment method, human subject experiments were performed to investigate the subjective discomfort levels through a questionnaire for comparison with the objective discomfort levels. The validation results showed that the correlation between the objective and subjective discomforts was significant and could be described by a linear regression model.

Evaluating a prototype device designed to alleviate night vision goggle induced neck strain among military personnel.

The purpose of this study was verify the design of a novel Helmet System Support Device (HSSD) that can be used by military aircrew to help intervene on and reduce the high prevalence of neck trouble. Twelve healthy participants repeated simulated helicopter aircrew tasks on 3 separate days. On each day they wore a different helmet configuration, where measures of performance, perceived demand/preference and muscular demand were recorded. The results showed that vigilance tasks were performed over 10% faster with the HSSD configuration compared to wearing the normal helmet configuration. Participants were able to maintain static (endurance) postures for 28% longer, and use of the HSSD helped to prevent neck muscle fatigue in the most demanding task. The results of this design verification study indicate that the HSSD may be a realistic, feasible near-term solution to intervene on the high prevalence of neck trouble among rotary-wing aircrew. Practitioner Summary: This paper verifies the effectiveness of the Helmet System Support Device (HSSD) as an on-body personal protective device to help control exposures associated with aircrew neck trouble. The HSSD reduced perceived demand, reduced cumulative muscle activity in select muscles and provided improved fatigue resistance, meeting its desired design objectives.

A systematic review of camera monitor system display layout designs: Integration of existing knowledge.

Despite the growing interest in mirrorless vehicles equipped with a camera monitor system (CMS), the human factors research findings on CMS display layout design have not been synthesized yet, hindering the application of the knowledge and the identification of future research directions. In an effort to address the 'lack of integration of the existing knowledge', this literature review addresses the following research questions: 1) what CMS display layout designs have been considered/developed by academic researchers and by automakers, respectively?; 2) among possible CMS display layout design alternatives, which ones have not yet been examined through human factors evaluation studies?; and 3) how do the existing human factors studies on the evaluation of different CMS display layout designs vary in the specifics of research? This review provides significant implications for the ergonomic design of CMS display layouts, including some potential design opportunities and future research directions.

Using a quantitative assessment of propulsion biomechanics in wheelchair racing to guide the design of personalized gloves: a case study.

This study with a T-52 class wheelchair racing athlete aimed to combine quantitative biomechanical measurements to the athlete's perception to design and test different prototypes of a new kind of rigid gloves. Three personalized rigid gloves with various, fixed wrist extension angles were prototyped and tested on a treadmill in a biomechanics laboratory. The prototype with 45° wrist extension was the athlete's favourite as it reduced his perception of effort. Biomechanical assessment and user-experience data indicated that his favourite prototype increased wrist stability throughout the propulsion cycle while maintaining a very similar propulsion technique to the athlete's prior soft gloves. Moreover, the inclusion of an innovative attachment system on the new gloves allowed the athlete to put his gloves on by himself, eliminating the need for external assistance and thus significantly increasing his autonomy. This multidisciplinary approach helped to prototype and develop a new rigid personalized gloves concept and is clearly a promising avenue to tailor adaptive sports equipment to an athlete's needs.

Proposal for a new statistical procedure for the ergonomic design of furniture: implications of a protocol developed from measurements of a young population.

The current approach to the ergonomic design of furniture often relies on a gender-based segmentation, assuming that it yields homogeneous groups. However, this assumption has proved to be inconsistent in various contexts, particularly in regions characterized by ethnic diversity and economic inequalities, leading to diverse anthropometric characteristics. Considering gender alone fails to encompass this heterogeneity. The proposed approach introduces an 'anthropometric segmentation' methodology in which the population is clustered based on a wide range of anthropometric dimensions. Additionally, kernel density estimation is used when normality is not fulfilled. This step is critical, as it informs furniture dimensions by using selected percentiles from these density functions. The proposed approach is applied to a dataset of university students in Peru, a country marked by significant heterogeneity within its male and female populations. Ultimately, our methodology promises to improve the ergonomic design of furniture by accounting for a broader spectrum of anthropometric diversity.

Designing an adjustable ergonomic laptop desk and its evaluating by RULA and NERPA methods.

BACKGROUND: Using a computer may lead to pain in wrists, neck, and back. In addition, adopting various body postures like sitting cross-legged, semi-fowler's position, and putting the laptop on the leg may lead to the development of persistent and irreversible discomfort. OBJECTIVE: The purpose of this research is to design and build an adjustable ergonomic laptop desk based on the anthropometric characteristics of students in the age range of 20 to 30 years and to evaluate its efficiency using RULA and NERPA methods. METHODS: This cross-sectional study conducted on 108 students, in which an adjustable and portable ergonomic desk designed and built based on 10 anthropometric dimensions of students and the length and width of 10 different laptop models. Two assessment methods, RULA and NERPA, were used. Wilcoxon statistic test and SPSS version 26 software used for data analysis. RESULTS: The dimensions of the desk were calculated in three positions, and the desk was made with the ability to adjust height, width and tilt, each with two degrees of freedom. The statistical analysis comparing score of RULA and NERPA in two situations without using a desk and using an ergonomic laptop desk had a significant difference (P-value <  0.001). Comparison of RULA and NERPA scores showed that NERPA evaluated the low ergonomic risk level better than RULA method. CONCLUSIONS: Due to the ability to adjust the designed desk, the changes in RULA and NERPA score in all three modes, it indicates the effectiveness of the table in improving the body posture of users when using a laptop.

Gesture-Controlled Robotic Arm for Agricultural Harvesting Using a Data Glove with Bending Sensor and OptiTrack Systems.

This paper presents a gesture-controlled robotic arm system designed for agricultural harvesting, utilizing a data glove equipped with bending sensors and OptiTrack systems. The system aims to address the challenges of labor-intensive fruit harvesting by providing a user-friendly and efficient solution. The data glove captures hand gestures and movements using bending sensors and reflective markers, while the OptiTrack system ensures high-precision spatial tracking. Machine learning algorithms, specifically a CNN+BiLSTM model, are employed to accurately recognize hand gestures and control the robotic arm. Experimental results demonstrate the system's high precision in replicating hand movements, with a Euclidean Distance of 0.0131 m and a Root Mean Square Error (RMSE) of 0.0095 m, in addition to robust gesture recognition accuracy, with an overall accuracy of 96.43%. This hybrid approach combines the adaptability and speed of semi-automated systems with the precision and usability of fully automated systems, offering a promising solution for sustainable and labor-efficient agricultural practices.

Design and ergonomic evaluation of a new adapted endoscope holder to reduce muscle pressure and discomfort during endoscopy.

BACKGROUND: Laparoscopic surgeons who regularly perform endoscopy are more likely to develop musculoskeletal disorders than other internal medicine specialists, a difference that attributed to repetitive movements, poor postures, and sub-optimal equipment design. OBJECTIVE: This study aimed to design, build, and evaluate an endoscope holder for reducing the static load applied by the weight of the endoscope, in order to reduce musculoskeletal disorders risk factors in the surgeon's hand, shoulder and back issues regions. METHODS: A new endoscope holder was designed according to ergonomic design principles. The designed holder was evaluated by surface electromyography (sEMG) and discomfort assessment including 15 laparoscopic surgeons. The results were analyzed with centrality statistics and compared with the independent t-test using SPSS version 22. RESULTS: The evaluation of the new endoscope holder shows a statistical significant decrease in the average electrical activity of biceps brachii, triceps brachii, lateral deltoid, T9 Thoracic erector spinae, L4 Lumbar erector spinae, and external oblique after using the holder (p < 0.05). CONCLUSION: The results shows that using the new endoscope holder is associated with a lower level of discomfort, as well as a lower induced muscle activity. The results also highlight the need to upgrade the holder to offer rotability in all directions (perpendicular to the ground) which will be included in the next design.

Study of The Impact of Users' Features on Dimensional Allowances Resulting from the Use of Personal Protective Equipment.

Up-to-date anthropometric data on the human population are needed for designing safe and ergonomically efficient workplaces. An important determinant of safety and ergonomic comfort at work is knowledge of the value of dimensional allowances (DAs) when using personal protective equipment (PPE) as the dimensions and space occupied by workers increase. This is particularly important in environments characterized by spatial constraints. However, it is not well known to what extent the aforementioned DAs are affected by the users' features. The anthropometric dimensions of 200 people (151 males and 49 females) were obtained from 3D scans, and these became the basis for calculating DAs when using PPE kits normally worn by rescue and technical workers. DAs were determined for the entire body shape of a person wearing three types of PPE kits designed for firefighters, mine rescuers, and welders. In the study, maximum and mean values of height, width, and circumference DAs were obtained. In addition, percentage dimensional increments (DIs) were calculated. A three-dimensional analysis of the human body with and without PPE, involving a 3D scanning methodology, was applied to address the research question. Test results clearly indicate that the values of DAs do not depend on the anthropometric features of users, such as sex, age, and body height percentile-they remain constant for a given type of PPE. The presented data are useful for designing PPE products as well as work tools and infrastructure, including machinery, devices, workstations, means of transport, interiors, and building equipment. The results of the presented study indicate that dimensional allowances play a significant role in interactions between persons wearing PPE and their work environments. The obtained results (DAs and percentage DIs) are included in a new anthropometric atlas of human measures developed by the CIOP-PIB in 2023.

Applying the quick exposure check in the workstation design process, physical and virtual prototype assessment.

BACKGROUND: The Quick Exposure Check (QEC) assesses four major body parts and engages users in assessing some physical interactions relevant to design in task analysis. OBJECTIVE: In this paper, we investigated the application of QEC as the ergonomic intervention to detect pre-production ergonomic design faults in the apple sorting machine by applying physical and virtual prototyping for three different tasks analysis divided into two phases (Task 1: Apple harvesting and preparation for sorting; Task 2: Sorting control and separation of waste fruits; Task 3: Transfer of separated apples). METHOD: First, the QEC questionnaire was administered while Iranian participants interacted with the machine to detect abnormal posture. Second, we redesigned a concept of the machine and assessed it with QEC by a focus group. RESULTS: Before design, the high pressure in Task 1 is on the back (dynamic), shoulder/arm, and very high pressure in Task 2, and in Task 3 on the back (static), arm/shoulder/neck, making an uncomfortable situation for posture. After redesign, we observed decreased pressures on the back/shoulder/arm in Task 1 from high to medium, in Task 3 from very high to low, and also in Task 2, this was detectable decreasing from very high pressures on the back/shoulder/arm and the high pressures on the neck to medium. CONCLUSION: Prototyping with QEC demonstrated that accurate redesigning of the machine with concentration on shifting from static tasks to dynamic or conversely, and ease of access by adjusting dimensions according to anthropometry and auxiliary products, could reduce musculoskeletal disorders.

Design of Innovative Clothing for Pressure Injury Prevention: End-User Evaluation in a Mixed-Methods Study.

The global relevance of pressure injury (PI) prevention technologies arise from their impact on the quality of life of people with limited mobility and the costs associated with treating these preventable injuries. The purpose of this mixed methods study is to evaluate the design of a prototype integrating Smart Health Textiles for PI prevention based on feedback from specialist nurses who care for individuals who are prone to or have PIs. This is a mixed methods study. A structured questionnaire was conducted as part of an evaluation of a prototype garment for the prevention of PIs. This questionnaire was applied during the evaluation of the prototype and afterwards focus group discussions were held with experts. Descriptive statistics techniques were used to analyze the data and thematic and integrated content analysis was conducted through concomitant triangulation. Nineteen nurses took part, aged 30 to 39 years (52.6%) and with 12.31 ± 8.96 years of experience. Participants showed that the prototype required more manipulation and physical effort, which interfered its usefulness, in addition to presenting difficulties with the openings and the material of the closure system, which interfered with the ease of use and learning. Overall satisfaction with the product was moderate, with some areas for improvement found, such as satisfaction, recommendations to colleagues, and pleasantness of use. It is concluded that areas for improvement have been found in all dimensions, including in the design of openings and the choice of materials. These findings supply significant insights for improving clothing to meet the needs of healthcare professionals and patients.

Development of a Hip Joint Socket by Finite-Element-Based Analysis for Mechanical Assessment.

This article evaluates a hip joint socket design by finite element method (FEM). The study was based on the needs and characteristics of a patient with an oncological amputation; however, the solution and the presented method may be generalized for patients with similar conditions. The research aimed to solve a generalized problem, taking a typical case from the study area as a reference. Data were collected on the use of the current improving prosthesis-specifically in interaction with its socket-to obtain information on the new approach design: this step constituted the work's starting point, where the problems to be solved in conventional designs were revealed. Currently, the development of this type of support does not consider the functionality and comfort of the patient. Research has reported that 58% of patients with sockets have rejected their use, because they do not fit comfortably and functionally; therefore, patients' low acceptance or rejection of the use of the prosthesis socket has been documented. In this study, different designs were evaluated, based on the FEM as scientific support for the results obtained, for the development of a new ergonomic fit with a 60% increase in patient compliance, that had correct gait performance when correcting postures, improved fit-user interaction, and that presented an esthetic fit that met the usability factor. The validation of the results was carried out through the physical construction of the prototype. The research showed how the finite element method improved the design, analyzing the structural behavioral, and that it could reduce cost and time instead of generating several prototypes.