Comfort Driven Redesign: The Case of Library Chairs

AbstractUniversity students spend most of their time in a sitting position. Prolonged sitting on ill-fitted furniture and the resulting lousy posture is making students having different musculoskeletal disorders and is strictly related to students learning outcomes. This study aims to improve postural comfort of chairs placed inside the Science & Technology Library at the University of Salerno. A previous study about these library chairs showed that the lumbar area was the most suffering part while perceived (dis)comfort was dependent on time. Based on this, an ergonomic redesign and, consequently, manufacturing of the chair has been done. A perceived-comfort comparison between the library chair and the redesigned one has been performed. A statistical sample of 28 healthy students performed a 20-min experiment two times, alternatively on the library chair and the redesigned one. The 20-min experiment was divided into two 10-min tasks ("Reading & Writing" and "Laptop use") to simulate a study day. The participants' postures were acquired non-invasively using cameras and processed by Kinovea; questionnaires were used to rate the perceived subjective (dis)comfort. A procedure for improving an existing product through a comfort-driven redesign is proposed. Results showed the redesigned library chair lead on increasing postural comfort (particularly in the lumbar area) thanks to the new design and modifications

A method for postural critical factors checking: The case of library chairs

BACKGROUND:According to ergonomic researches regarding a good sitting posture, it is essential to ensure a natural back-curve in order to prevent musculoskeletal disorders. A brief observation among the Scientific Technology Library inside the University of Salerno showed that students used to complain about neck and lumbar pain, especially after a study day. OBJECTIVE:On the light of this background, a sitting posture comfort analysis had been performed on chairs inside the library to check the critical factors that influence the postural comfort and, consequently, the learning. METHODS:A prolonged sitting posture, that is common during the daily study activity, had been simulated with fifteen volunteer students performing 1-hour tests (divided into four 15-minutes tasks). Subjective perceptions had been gathered through questionnaires rating on a 5-point Comfort scale, both the expected comfort at the beginning of the experiment and the Localized Postural Comfort at the end of each task have been investigated. Then, postural angles had been gathered through photographic acquisition and Kinovea®. CaMAN software had been used to calculate the objective (dis)comfort indexes. Finally, subjective and objective data had been statistically processed and compared. RESULTS:Lumbar area scored the lowest perceived comfort while the perceived comfort was independent of participants and tasks, but dependent on time. CONCLUSIONS:After this comfort-driven analysis, critical factors of the chair-design were checked, and a proposal for a future re-design was hypothesized

A comfort evaluation tool for sitting postures: the case of Library chairs

According to ergonomic researches regarding a good sitting posture, the chair, the desk and the objects on the desk, have to be aligned in a certain way to ensure to users a natural curve of the back in order to prevent musculoskeletal disorders. A brief observation among the main Scientific Technology Library inside the University campus showed that students used to complain about neck and lumbar pain, especially after a study day. Thus, a sitting posture comfort analysis had been performed on chairs inside the library. A long-time sitting posture during the daily study activity had been simulated with fifteen volunteer students performing 1-hour tests (divided into four tasks of 15 minutes each). Subjective perceptions had been gathered through questionnaires rating on a 5-point Likert scale both the expected comfort at the beginning of the experiment, and the Localized Postural Comfort at the end of each task. Moreover, just before the end of each task, postural angles had been detected by photographic acquisition and processed by Kinovea®; in addition, CAMan® software had been used to calculate the (dis)comfort indexes by detected postural angles. Finally, subjective and objective data had been statistically processed and compared. Results showed the lumbar area as the most suffering area (lower perceived comfort) while perceived (dis)comfort was independent on participants and tasks, but dependent on the time

Discomfort Threshold Evaluation for Hand and Elbow Regions: A Basis for Hand-Held Device Design

This study aimed to analyse the discomfort threshold (that could be linked to sensitivity or sensation) of different regions in hand and elbow to support hand-held devices' design. Indeed, there are no studies regarding the hand and elbow discomfort threshold or sensitivity. To overcome these literature gaps, the discomfort threshold of hand and elbow were recorded at 24 spots by pushing a cylinder with a diameter of 10 mm until the participants reported not to be longer comfortable. Experiments were performed with 24 participants, 13 females and 11 males. The results showed the map of discomfort threshold (or sensitivity) for the hand and elbow. The olecranon, situated at the ulna's upper (proximal) end, one of the two bones in the forearm, could withstand more pressure than the elbow area surrounding it. The fingertips and the area close to the metacarpals were most sensitive (lower discomfort threshold).</p

Designing a shaped seat-pan cushion to improve postural (dis)comfort reducing pressure distribution and increasing contact area at the interface

Remaining seated for extended periods increases the risk health issues and discomfort perception. Consequently, the seat-pan design is crucial and could be mainly influenced by two factors: pressure distribution and seat contour. For seat pan discomfort, the lower average pressure is accompanied by less discomfort. Moreover, a seat contour with a large contact area is correlated with more comfort. Thus, a shaped cushion had been accurately designed (Virtual Prototype) and realized (Physical Prototype) aiming to translate the pressure distribution due to interaction between seat and buttock in a geometric shape, suitable for the international population (including P5 females and P95 males). With this shape, the pressure should be more uniform and lower, the contact area at interface bigger, and the perceived comfort higher. Both Virtual and Physical Prototype design had been described in this paper through a repeatable and straightforward approach. Also, experiments had been performed to validate the hypothesis through a comparison with a standard flat cushion. Results showed the goal of the design had been reached: the shaped cushion scored less pressure distribution and higher contact area than the flat cushion.Materials and ManufacturingMechatronic Desig

Discomfort Threshold Evaluation for Hand and Elbow Regions: A Basis for Hand-Held Device Design

This study aimed to analyse the discomfort threshold (that could be linked to sensitivity or sensation) of different regions in hand and elbow to support hand-held devices' design. Indeed, there are no studies regarding the hand and elbow discomfort threshold or sensitivity. To overcome these literature gaps, the discomfort threshold of hand and elbow were recorded at 24 spots by pushing a cylinder with a diameter of 10 mm until the participants reported not to be longer comfortable. Experiments were performed with 24 participants, 13 females and 11 males. The results showed the map of discomfort threshold (or sensitivity) for the hand and elbow. The olecranon, situated at the ulna's upper (proximal) end, one of the two bones in the forearm, could withstand more pressure than the elbow area surrounding it. The fingertips and the area close to the metacarpals were most sensitive (lower discomfort threshold).Accepted Author ManuscriptMaterials and ManufacturingIndustrial Design Engineerin

School combo-desk comfort assessment: A method for weighing postural factors that affect the overall perceived comfort

BACKGROUND:In recent years, a growing interest in ergonomics and comfort perception in secondary schools and universities can be detected, to go beyond the UNI-EN regulations and understanding how practically improve students’ perceived comfort during lessons. OBJECTIVE:This study aimed to analyse the (dis)comfort perceived by students while sitting in a combo-desk during lessons; it proposed a method for understanding and weighing the influence of postural factors on overall (dis)comfort. METHODS:Twenty healthy students performed a random combination of three different tasks in two sessions - listening, reading on a tablet and writing. Subjective perceptions were investigated through questionnaires, in which the expected and the overall comfort were evaluated; postural angles were gathered by processing photos through Kinovea® software and were used for the virtual-postural analysis, using a DHM (Digital Human Modelling) software; statistical analysis was used to investigate the influence of subjective comfort of each body part on the overall perceived comfort. RESULTS:The statistical correlations were used to perform an optimization problem in order to create a general law to formulate the overall comfort function, for each task, as a weighted sum of the comfort perceived in each body part. The test procedure, additionally, evaluated the influence on comfort over time. The results showed how the upper back and the task-related upper limb are the most influencing factors in the overall comfort perception. CONCLUSIONS:The paper revealed a precise and straightforward analysis method that can be easily repeated for other design applications. Obtained results can suggest to designers easy solution to re-design the combo-desk

Objective comparison of two cushions: pressure distribution and postural perceived discomfort

Designing seats is crucial not only for health issues but also for the (dis)comfort perception. The seat pan design could be mainly influenced by two factors: pressure distribution and seat contour. For seat pan discomfort, the lower average pressure is accompanied by less discomfort. Moreover, a seat contour with a large contact area is correlated with more comfort. So, a shaped seat pan was accurately realized following the buttock-thigh shape of an international population (including P5 females and P95 males). For the comfort assessment, a comparison was made between this shaped seat pan (shaped cushion) and a standard aircraft seat pan (flat cushion). Twenty-two internationalparticipants (11 males and 11 females, with BMI between 16 and 30) took part in the blind experiment assuming six different postures. Subjective data were gained from questionnaires, whose results showed that the shaped cushion is better in terms of perceived postural comfort. Also, 64% of participants chose the shaped cushion as a preferred cushion because it was more comfortable and suitable for the buttock shape. Objective data were gathered with a pressure mat, and results showed a higher contact area and lower mean pressure distribution for shaped cushion. Significant correlations were calculated between objective and subjective data with Spearman Correlation coefficients.Mechatronic DesignMaterials and Manufacturin

School combo-desk comfort assessment: a method for weighing postural factors that affect the overall perceived comfort while performing different activities

t In recent years, a growing interest in ergonomics and comfort perception in secondary schools and universities can be detected, with the aim of going beyond the UNI-EN regulations and understanding how practically improve students’ perceived comfort during lessons. The aim of this study was to analyse the discomfort perceived by students while sitting on combo-desk during lessons. A statistical sample of 20 healthy students performed a combination of three different tasks in two sessions - listening, reading on a tablet and writing - in a mixed sequence. Subjective perceptions were investigated through questionnaires, in which the expected comfort and the overall one were rated on a 10-point comfort scale and the perceived comfort on a 5-point Likert scale. Subject’s postures were acquired non-invasively using cameras; Kinovea® software was used to detect postural angles directly on pictures; the acquired angles were used for the virtual-postural analysis, using a DHM (Digital Human Modelling) software; CaMAN® software was used to obtain an objective measure of the postural comfort. Once correlations between subjective and objective data were calculated, the results of the analysis were used to define the influence of each body part comfort on the overall perceived comfort and to quantify the weight of each factor influencing the overall perception. Finally, some guidelines to modify the combodesk design, in order to increase the level of perceived comfort, were developed