A medical hand tool physical interaction evaluation approach for prototype testing using patient care simulators

peer-reviewedThe purpose of this study was to develop and test a physical ergonomics assessment approach for medical device handles. The method assesses wrist posture and force of exertion simultaneously by task element. Electrogoniometers and EMG sensors were connected through a data acquisition module for synchronization with video recordings of trials. Task analysis of video recordings were performed offline with Observer XT software. Average posture and force data across several repetitions of individual task elements were calculated and presented in a format suitable for informing product designers of specific issues during a test trial. A handle comfort questionnaire is proposed to survey subjective responses. The evaluation approach was applied to an endoscope needle in sampling a biopsy from the stomach wall using a gastrointestinal track simulator with ten physician surrogates. The results showed that for all task elements the wrist was in extension (33 degrees-45 degrees). Peak muscle forces ranged from 28% to 68% MVC across the three muscles studied. Muscle peak forces were above ACGIH HAL maximum threshold limits for four of the seven task elements, and above the action limit for all seven task elements for two muscles. The handle comfort questionnaire data also supported the high muscle force findings, and also on force distribution on the handle due to contact stresses. This combined approach could be used to collect and report detailed early stage ergonomics data from user trials on patient care simulators. The approach is proposed for use by medical device designers at the design stage of new products using prototypes, but it could also be used on existing products with real patients. (C) 2011 Elsevier Ltd and The Ergonomics Society. All rights reserved.ACCEPTEDpeer-reviewe

Improving long term driving comfort by taking breaks - how break activity affects effectiveness

During long duration journeys, drivers are encouraged to take regular breaks. The benefits of breaks have been documented for safety; breaks may also be beneficial for comfort. The activity undertaken during a break may influence its effectiveness. Volunteers completed 3 journeys on a driving simulator. Each 130 min journey included a 10 min break after the first hour. During the break volunteers either stayed seated, left the simulator and sat in an adjacent room, or took a walk on a treadmill. The results show a reduction in driver discomfort during the break for all 3 conditions, but the effectiveness of the break was dependent on activity undertaken. Remaining seated in the vehicle provided some improvement in comfort, but more was experienced after leaving the simulator and sitting in an adjacent room. The most effective break occurred when the driver walked for 10 min on a treadmill. The benefits from taking a break continued until the end of the study (after a further hour of driving), such that comfort remained the best after taking a walk and worst for those who remained seated. It is concluded that taking a break and taking a walk is an effective method for relieving driving discomfort

Distracting people from sources of discomfort in a simulated aircraft environment

BACKGROUND: Comfort is an important factor in the acceptance of transport systems. In 2010 and 2011, the European Commission (EC) put forward its vision for air travel in the year 2050 which envisaged the use of in-flight virtual reality. This paper addressed the EC vision by investigating the effect of virtual environments on comfort. Research has shown that virtual environments can provide entertaining experiences and can be effective distracters from painful experiences. OBJECTIVE: To determine the extent to which a virtual environment could distract people from sources of discomfort. METHODS: Experiments which involved inducing discomfort commonly experienced in-flight (e.g. limited space, noise) in order to determine the extent to which viewing a virtual environment could distract people from discomfort. RESULTS: Virtual environments can fully or partially distract people from sources of discomfort, becoming more effective when they are interesting. They are also more effective at distracting people from discomfort caused by restricted space than noise disturbances. CONCLUSIONS: Virtual environments have the potential to enhance passenger comfort by providing positive distractions from sources of discomfort. Further research is required to understand more fully the reasons why the effect was stronger for one source of discomfort than the other

Sitting comfort and discomfort and the relationships with objective measures

The concepts of comfort and discomfort in sitting are under debate. There is no widely accepted definition, although it is beyond dispute that comfort and discomfort are feelings or emotions that are subjective in nature. Yet, beside several subjective methodologies, several objective methods (e.g. posture analysis, pressure measurements, electromyography (EMG)) are in use to assess sitting comfort or discomfort. In the current paper a theoretical framework is presented, in which comfort and discomfort were defined and the hypothetical associations with underlying factors were indicated. Next, the literature was reviewed to determine the relationships between objective measures and subjective ratings of comfort and discomfort. Twenty-one studies were found in which simultaneous measures of an objective parameter and a subjective rating of comfort or discomfort were obtained. Pressure distribution appears to be the objective measure with the most clear association with the subjective ratings. For other variables, regarding spinal profile or muscle activity for instance, the reported associations are less clear and usually not statistically significant

Reducing work-related Musculoskeletal Disorders (MSDs) through design: Views of ergonomics and design practitioners

This is the accepted manuscript version of the article. The definitive published version is available at: http://dx.doi.org/10.3233/WOR-152126BACKGROUND: Work-related Musculoskeletal Disorders (MSDs) affect the well-being of workers. Unfortunately, user requirements for design to reduce workplace risk factors for MSDs are not always effectively communicated to designers creating a mismatch between the user requirements and what is ultimately produced. OBJECTIVE: To understand the views of practitioners of design and ergonomics regarding tools for participatory design and features they would like to see in such tools. METHODS: An online questionnaire survey was conducted with a cohort of practitioners of ergonomics and design (n=32). In-depth interviews were then conducted with a subset of these practitioners (n=8). To facilitate discussion, a prototype integrated design tool was developed and demonstrated to practitioners using a verbalized walkthrough approach. RESULTS: According to the results of the questionnaire survey, the majority (70%) believed an integrated approach to participatory design would help reduce work-related MSDs and suggested ways to achieve this, for example, through sharing design information. The interviews showed the majority (n=7) valued being provided with guidance on design activities and ways to manage and present information. CONCLUSION: It is believed that an integrated approach to design in order to help reduce work-related MSDs is highly important and a provision to evaluate design solutions would be desirable for practitioners of design and ergonomics

Skin tribology: Science friction?

The application of tribological knowledge is not just restricted to optimizing mechanical and chemical engineering problems. In fact, effective solutions to friction and wear related questions can be found in our everyday life. An important part is related to skin tribology, as the human skin is frequently one of the interacting surfaces in relative motion. People seem to solve these problems related to skin friction based upon a trial-and-error strategy and based upon on our sense for touch. The question of course rises whether or not a trained tribologist would make different choices based upon a science based strategy? In other words: Is skin friction part of the larger knowledge base that has been generated during the last decades by tribology research groups and which could be referred to as Science Friction? This paper discusses the specific nature of tribological systems that include the human skin and argues that the living nature of skin limits the use of conventional methods. Skin tribology requires in vivo, subject and anatomical location specific test methods. Current predictive friction models can only partially be applied to predict in vivo skin friction. The reason for this is found in limited understanding of the contact mechanics at the asperity level of product-skin interactions. A recently developed model gives the building blocks for enhanced understanding of friction at the micro scale. Only largely simplified power law based equations are currently available as general engineering tools. Finally, the need for friction control is illustrated by elaborating on the role of skin friction on discomfort and comfort. Surface texturing and polymer brush coatings are promising directions as they provide way and means to tailor friction in sliding contacts without the need of major changes to the produc

The design of Artisans' hand tools: Users' perceived comfort and discomfort

Is artisans' comfort in using hand tools a necessity or a luxury? Ergonomically well-designed hand tools, which provide comfort to the user, decrease the risk of occupational health problems and increase the job performance. Therefore, it is not a luxury, but rather a necessity that hand tools be designed with a focus on comfort, and that artisans make themselves informed about the use of ergonomically well-designed hand tools. © Springer Science + Business Media, LLC 2009

Ergernomie verstelbare steel

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