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Wearing an object in the rear pocket alters the interface between the body and the chair, leading to the compression of the sciatic nerve. Prolonged sitting behaviors with such objects can lead to a health disorder called Piriformis Syndrome. In this paper, we use an intelligent office chair in order to detect the wallet usage as a “bad sitting posture”, as sitting on a wallet can create an uneven sitting surface, subsequently tilting the pelvis in the frontal plane. The system is comprised of a pneumatic circuit and is able to detect and classify, based on Artificial Neural Network, 12 standardized sitting postures, with an accuracy of 80.9%. In this test, we asked 36 subjects (24 males-M and 12 females-F) to wear a wallet in the back pocket in 12 testing levels, based on 3 wallets sizes (small, medium and large) and 4 levels of wallet heights (no paper cards, 8 cards, 16 cards and 24 cards). We detected the usage of wallets as an incorrect posture in 58.8% for all levels (61.1% for Male and 54.2% for Female). We observed that the size of the wallet did not alter results significantly (60.4% for smaller area versus 57.6% in the larger area), while the wallet height had a large influence (46.2% for no cards versus 71.3% for 24 cards). We also tested wallet usage in the front pocket with an average of 16.7%, showing that this usage doesn't alter significantly the sitting posture. This work shows that the creation of an alert protocol for the wallet usage is possible to be implemented in our intelligent chair system.

Objective: The objective of this study was to define the Dynamic Sitting (DS) through trend analysis and research on the Dynamic Chair (DC) and applied technologies. Background: The effects of changing posture on the human body have been studied to find out healthy sitting postures. It is believed that changing posture is effective in reducing disc pressure on spinal cord and preventing back pain and musculoskeletal disease. But, the definition of DS and trends of DC have not been researched yet. Therefore, trend analysis of DC and its applied technologies are required to define dynamic sitting posture. Method: We researched the type of occupant postures from previous studies. And then, sitting behaviors were classified into three types; (1) sitting and standing, (2) working and studying, (3) taking a rest. Results: Variety shapes of DC and applied technologies were found out. From the result, the trend of DC and applied technology were summarized from three perspectives. ; (1) changing the chair functions according to user"s intention, (2) conversion of dynamic chair technologies to office chair mechanism, (3) enables the user to change their sitting posture without operating control device. Conclusion: From this study, we defined dynamic sitting posture and analyzed the trend of DC and its applied technologies. This result might be used to develop an office chair for healthy sitting. But further investigation is required to figure out the technologies and functions for development of healthy chair. Application: The results of the publishing trend analysis might help to determine design concept of office chair.

Human sitting posture and dynamic behavior at work are analyzed systematically by using the principle and method of ergonomics. And from the scales and functionality limited by both aspects, put forward new design ideas of office chair which are fit to modern office work so as to provide reference to design practice.

Objective: The aim of this study is to develop an office chair enabling to keep working at reclined sitting posture. Background: Sedentary workers are supposed to change the posture frequently during long hours of sitting. A reclined sitting position has been recommended to reduce disc pressure. But slumped sitting posture caused by the buttock sliding forward without any adjustment of back reclining is commonly observed. The worker seems to have tendency to change the sitting posture maintaining working condition. We assumed the reason to be their hands movement away from the working space when tilting backward. Method: Slide mechanism allowing seat to move forward was designed to maintain the hand position in working space during reclining. A prototype was manufactured and tilting motion was analyzed using motion capture system. Four experiment chairs were tested including the manufactured prototype chair and three other commercial chairs. Results: A backward movements of the hand position were 13.0mm, 101.7mm, 156.1mm and 139.3mm at the prototype chair, compared to chair B, chair C and chair D, respectively. And the movement was remarkably small at the prototype chair. Conclusion: The developed seat sliding chair allows back tilting maintaining hand position at working space. We expect the user tilting back more often than normal tilting chair during seated work. But further investigation is required to figure out the effectiveness of the developed chair using prolonged working hours. Application: The developed office chair directly affects commercialization.

To propose technical difficulties of PDM applied in China office chair industry, and puts forward a solution for the coding problem: first presents a PDM-based classification method of office chair products and parts; Constructed the Office Chair Product Information Tree and base on it established Office Chair Enterprise Information Coding System framework; Base on the classification method and reference the relevant standards, introduce the Tabular Layouts of Article Characteristic, the office chair coding scheme is developed. The coding technology has been verified by applying on Kingdee WISE K/3 PLM system. For the problem of office chair non-digital product data digitization, puts forward the Office Chair Template Data Acquisition & Output Technology, to digitalise the non-digital data for facilitating the PDM system to manage, share to CAM equipment. The technology has been successfully applying to Landmega Furniture Co., Ltd.

Customer satisfaction is considered as the most important factor in designing a product ergonomically. Products should satisfy customer's choice of preference in terms of their comfort level. So choosing a product with optimum design characteristics in order to achieve customer satisfaction is essential. Since it is difficult to find out an optimum set of design parameters for a product in order to meet all customers’ need, a feasible way considering Multi Criteria Decision Making (MADM) approach is used to select a product carrying all the specified function. This paper proposes a framework of MADM based on Visekriterijumsko kompromisno rangiranje (VIKOR) method to select ergonomically designed office chair in order to improve the comfort level. Keeping customer preference in mind ten design characteristics (attributes) and six alternatives are considered to develop the framework. The proposed method considers decision maker's (DM'S) preference to judge this parameter in order to fit the product to a range of user.

To propose technical difficulties of PDM applied in China office chair industry, and puts forward a solution for the coding problem: first presents a PDM-based classification method of office chair products and parts; Constructed the Office Chair Product Information Tree and base on it established Office Chair Enterprise Information Coding System framework; Base on the classification method and reference the relevant standards, introduce the Tabular Layouts of Article Characteristic, the office chair coding scheme is developed. The coding technique has been verified by applying on Kingdee WISE K/3 PLM system.

When ergonomic criteria are separately applied to the design of chairs, the feeling of comfort is not guaranteed. In this case, the aesthetic and perceptive features of the chair provide the sensations of comfort, and several studies have determined that comfort and discomfort present some characteristics that make them different from each other. Moreover, early judgements by the user remain invariable when there is no interaction between the person and the object. Therefore, it can be assumed that if a device is considered comfortable after an initial experience of use, it may well not be thought as such after extended use. Based on this, the present research study aimed at establishing the differences in the perceptions of comfort of two chairs before and after extended sitting posture. Six subjects participated in this study, all they were women from 20 to 45 years of age, who usually perform office work in extended sitting posture, with a body mass index (BMI) ranging between 20 and 30 Kg/m2. In the experiment, four office tasks were assigned (reading, transcribing a text, handwriting and searching on the internet) during sixty minutes. The experiment was divided into two sessions, in order to use the two chairs subject of the study. Each participant was assessed at the same hour but in two different days. By means of the semantic differential, evaluations of visual perception were carried out by the participants before and after using the chair. The results reveal differences in the perception evaluation of both chairs before and after their use. In the case of the chair a, the assessment of the adjectives never decreased. This study shows that the pleasure provided by a product is not static and it does evolve on the basis of product time of use and manipulation. Even though there were no statistical differences in the adjective pairs studied when only one chair is examined, it was demonstrated that its perception may improve or worsen on the basis of time. Similarly, this perceptual behavior is not indifferent to the object, finding significant differences before and after use when comparing the chairs. Finally, this analysis tool provides better evidence on product functionality by indicating whether there are failures in the proposed design.

The relationships between sedentary lifestyle, sitting behaviour, and low back pain (LBP) remain controversial. In this study, we investigated the relationship between back pain and occupational sitting habits in 64 call-centre employees. A textile pressure mat was used to evaluate and parameterise sitting behaviour over a total of 400 h, while pain questionnaires evaluated acute and chronic LBP. Seventy-five percent of the participants reported some level of either chronic or acute back pain. Individuals with chronic LBP demonstrated a possible trend (t-test not significant) towards more static sitting behaviour compared to their pain-free counterparts. Furthermore, a greater association was found between sitting behaviour and chronic LBP than for acute pain/disability, which is plausibly due to a greater awareness of pain-free sitting positions in individuals with chronic pain compared to those affected by acute pain., Applied Ergonomics, 81, ISSN:0003-6870

Emerging evidence supports the feasibility of raising daily energy expenditure (EE) by replacing office work-related sedentary behavior with low-intensity non-exercise physical activity (PA) via workstation alternatives to the traditional office chair and desktop computer-based combinations. The purpose of this review article is to introduce a simple taxonomy to facilitate classification and study of workstation alternatives, catalog the diversity of research undertaken to date related to energy balance, and present and summarize the gaps and opportunities for a research agenda for workstation alternatives moving forward. A PubMed search elicited 57 English language articles published since 2000; additional articles were identified by reviewing reference sections and contacting authors. Selection criteria ultimately focused on use of workstation alternatives during simulated or real work tasks. The EE of sitting on a stability ball or using sit-stand/standing desks is comparable to the traditional seated condition (≅1.2 kcal min−1). The treadmill and pedal desks (active workstation alternatives) offer the greatest promise in terms of EE (≅2-4 kcal min−1). Sitting on a stability ball or using sit-stand/standing desks does not impair task performance relative to the traditional seated condition. Some evidence of typing impairment is inconsistently reported with active workstation alternatives; the finer motor skills required for mouse-related tasks may be more affected. Little is known about learning or adaptation with practice. Users are generally accepting of workstation alternatives; however, there is evidence of less than optimal use. Active workstations (that is, treadmill desks and pedal desks) in particular represent a potential strategy for mitigating the diminished EE inherent to contemporary office-based workplaces, but only if they are scalable. The science supporting active workstations is young and heterogeneous; however, this means that there are many knowledge gaps and opportunities for research, including those focused on implementation issues related to optimizing both employers' and workers' uptake. Refereed/Peer-reviewed

No study has examined the effectiveness of prescribing seating modifications according to the individual clinical presentation of people with low back pain (LBP). A dynamic, forward-inclined chair ('Back App') can reduce seated paraspinal muscle activation among pain-free participants. This study examined 21 participants whose LBP was specifically aggravated by prolonged sitting and was eased by standing. Low back discomfort (LBD) and overall body discomfort (OBD) were assessed every 15 min while participants sat for 1 h on both the dynamic, forward-inclined chair and a standard office chair. LBD increased significantly more (p = 0.005) on the standard office chair, with no significant difference (p = 0.178) in OBD between the chairs. The results demonstrate that, in a specific flexion-related subgroup of people with LBP, increased LBD during sitting can be minimised through modifying chair design. Mechanisms that minimise seated discomfort may be of relevance in LBP management, as part of a biopsychosocial management plan.This study examined low back discomfort (LBD) during a typing task among people with low back pain (LBP). Sitting on a dynamic, forward-inclined chair resulted in less seated LBD than sitting on a standard office chair. Further research is required to examine the long-term effectiveness of ergonomics interventions in LBP.

This paper employs a quality function deployment (QFD) methodology to translate customer requirements into design characteristics to improve the design of an office chair. A factor analysis has been carried out on the responses obtained from a cross sectional survey directed at users through a set of questionnaires. It has been obtained that three factors with twenty two items are loaded with a threshold value above 0.7. Finally, quality function deployment is used to extract important design characteristics satisfying the customer requirements

Objective: The aim of this study is to develop an ergonomic office chair that has an alarm function for the unbalanced sitting postures. Background: Contrary to expectation, it is reported that office workers sit on their chairs much more in unbalanced postures during daily work. Even though an office worker uses an ergonomically good-designed chair and begins their work in a good sitting posture, his/her posture is likely to shift to the unbalanced bad posture. Therefore, a posture alarm system would be very helpful in keeping office workers' good postures. Method: We developed a prototype chair with four load cells under a seat pan and one load cell beneath a backrest. Through some experiments, we set the criteria for unbalanced bad postures then implemented the criteria into the alarm system of the prototype chair. The chair called e-BASE chair could detect unbalance postures and show alarms for chair users. We also enhanced back support by developing a step-wised folding backrest. Results: The e-BASE chair showed better performance in interface pressure distributions and balanced posture ratio in VDT work. Conclusion: The ergonomic chair with posture alarm function(e-BASE chair) was developed. It showed better performance in seat pressure distribution and in keeping good posture during office work. Application: The posture alarm system and folding backrest can be applied to the new models of office chair.

Through the study of the seat size parameter change on the body pressure distribution effect, the powerful references to comfort design of office chair were explored. By using Canadian XSENSOR X3 PRO V6 test system, human body pressure distribution and subjective comfort evaluation in different back angle of 6 objects were tested. The data were processed by statistical analysis software SPSS 16. Then the change of maximum pressure, average pressure, contact area of seat surface and backrest, as well as the vertical pressure distribution curve with the back angle were obtained. Finally the comfort indicators of daily office chair were determined based on body pressure distribution, and the most comfortable back angle of office chair were also solved. Thereby it can provide reference for those who want to design comfortable daily office chair.

Starting from human design perspective of the product and using ergonomics knowledge, measurement method and model method are adapted to analyze harmonious relations between people in the sedentary state and office chairs in various parts. The research aims at how to correctly apply the theory of ergonomics in the design of new product development to ensure that the technical problems related to design fitness. And for the “Chair family ”--- the sedentary population, the user-friendly design elements of health office chairs, methods and performance evaluation are studied and summarized as well.

This paper presents a technique for writing-state classification by sedentary behavior sensing with a sensor-equipped chair, which wirelessly monitors the user's states such as behaviors or physiological and psychological conditions, for estimation of the user's subjective difficulty with a studying problem on a desktop. Avoiding user discomfort, four load cells are mounted behind the seat plate of a regular office chair. The system simply measures the weight and the center of pressure of the seat. These data are divided into time segments, which are labeled into four sedentary-body sway primitives by the decision tree algorithm, and then the behaviors are derived from the number and pitch of those primitives in a certain interval. In system-evaluation experiments, it achieved more than 80% labeling accuracy for untrained users. We conducted a user experiment showing its potential for desk work applications. The results of the experiment showed that our proposed system could classify user states into the writing state and other states such as reading a document and watching a movie at a classification rate of 87%.

Established the model of multifunctional office chair for fitness, using 3D modeling software Solidworks, finished the 3D model of parts and parts assembly according to the design requirements of multifunctional office chair, visually and efficientlly. Importantly, this chair is the combination of fitness and massage function. So it is practical and cnvenient to the office crowd.

Introduction Sedentariness is associated with chronic health conditions, impaired cognitive function and obesity. Work contributes significantly to sedentariness because many work tasks necessitate sitting. Few sustained solutions exist to reverse workplace sedentariness. Here, we evaluated a chair and an under-table device that were designed to promote fidgeting while seated. Our hypothesis was that an under-table leg-fidget bar and/or a fidget-promoting chair significantly increased energy expenditure. We compared these devices with chair-based exercise and walking. Materials and methods We measured energy expenditure and heart rate in 16 people while they sat and worked using a standard chair, an under-desk device that encourages leg fidgeting and a fidget-promoting chair. We compared outcomes with chair-based exercise and walking. Results Energy expenditure increased significantly while using either an under-table leg-fidget bar or a fidget-promoting chair, when compared to the standard office chair (standard chair, 76±31 kcal/hour; leg-fidget bar, 98±42 kcal/hour (p

A robust wireless system for capacitive ECG is presented, which measures electrode-body capacitive impedance, acceleration, and gyroscope signals from the electrodes to be used in motion artifact reduction algorithms. The system dynamically adapts its robustness and signal quality according to the environmental conditions. Optimizations including bias resistance and cancellation of common mode signals are discussed, and an office chair implementation is presented. An example of motion artifact compensation by means of an adaptive filter that uses the recorded signals is shown; and the dynamic adaptation to prevent front-end saturation is demonstrated and validated.

Purpose Dynamic chairs have the potential to facilitate movements that could counteract health problems associated with sedentary office work. This study aimed to evaluate whether a dynamic chair can increase movements during desk-based office work. Methods Fifteen healthy subjects performed desk-based office work using a dynamic office chair and compared to three other conditions in a movement laboratory. In a field study, the dynamic office chair was studied during three working days using accelerometry. Results Equivocal results showed that the dynamic chair increased upper body and chair movements as compared to the conventional chair, but lesser movements were found compared to standing. No differences were found between the conditions in the field study. Conclusions A dynamic chair may facilitate movements in static desk-based office tasks, but the results were not consistent for all outcome measures. Validation of measuring protocols for assessing movements during desk-based office work is warranted.

[Purpose] Working while sitting for long periods can cause lumbar pain, fatigue, and reduced work efficiency. How a dynamic chair with a seat that moves three-dimensionally affects pelvic mobility before and after work, work efficiency, and post-work fatigue were examined. [Subjects and Methods] Subjects were 17 healthy adults (10 males, 7 females, mean age 21.8 ± 2.7 years). Subjects performed a 30-min Kraepelin test under two conditions: sitting in a standard office chair and sitting in a dynamic sitting balance chair. Root mean square (RMS) values of pelvic movement measured by a triaxial accelerometer during 30 minutes of work, finger-floor distance before and after work, lumbar fatigue, and pelvic movement RMS values during finger-floor distance measurement were used as outcome measures. [Results] Pelvic movement RMS values collected every 5 minutes during 30 minutes of work were significantly higher while sitting in the dynamic balance chair. Changes in pelvic movement RMS values during finger-floor distance measurement after work and amount of work performed during 30 minutes were significantly higher and lumbar fatigue was significantly lower for the dynamic balance chair. [Conclusion] Dynamic sitting maintained or increased pelvic flexibility. The dynamic balance chair may effectively help workers work continuously in seated postures with little fatigue.

This paper presents the concept Backtive: an interactive office chair with an accompanying mobile application to provide both tactile and visual feedback for the user to correct his posture and make him more aware of the sitting behavior throughout the day. The concept aims to make people unintentionally and more voluntarily aware of their sitting behavior while not interrupting their daily tasks. The concept is developed through a user centered design approach and by building a prototype to test feasibility as well as evaluating the concept. An evaluation with four persons received positive results with regard to credibility and expectancy of Backtive for posture improvement. Participants also expect that Backtive would be easy in use and are likely to integrate the system in their daily activities.

This research applies the theory of human–machine–environment system engineering, using the measurement method to analyze the relationship between the user and the various components of the office chair in the sedentary condition. The measurement and analysis of the numerical value of the Chinese office crowd, find the basic design criteria of the modern office chair, which is seat height, seat width, seat depth, seat angle, seat back, and seat armrest. The research aims at optimizing modern office chair design and combining with human–machine–environment system engineering to make the design more scientific and reasonable.

The application of an integrated eco-design decision making tool is presented as a case study considering the design of an office chair base. This study brings together the analysis of factors relating to manufacturing processes, product usage and end-of-life strategy to demonstrate the operation of an eco-design case-based reasoning tool. This is shown to meet the requirement of the data storage, retrieval and re-use. A framework is provided to facilitate the application of sustainability criteria in the early design phase in a context with which designers are familiar. Such consideration can be made more understandable and relevant as more information is added. This makes all aspects of the process more rewarding for the participants and increases considerations of sustainability.

Functional objects, such as skis, chainsaw chains, kiwifruit trays and even pregnancy testing devices, are protected by copyright in New Zealand. Albeit the object itself is not protected by copyright, rather the drawings and other works underlying such objects are protected. Functional objects create challenges for copyright law and are not protected as broadly as more creative and expressive works: the designer of an office chair faces limitations imposed by physics, the artist painting a chair on canvas has no such obstacles. It is common for drawings that are necessary for the object to be manufactured to be done by people who did not generate the idea for the functional object. Sometimes the drawings will have been commissioned, other times not. Questions of ownership of drawings for functional objects can arise and then there is the question of infringement. This article explores the issues of commissioning, ownership and infringement of functional objects in New Zealand through the lens of litigation over a machine cup for an automatic asparagus grading machine.

Occupational musculoskeletal disorders, particularly chronic low back pain (LBP), are ubiquitous due to prolonged static sitting or nonergonomic sitting positions. Therefore, the aim of this study was to develop an instrumented chair with force and acceleration sensors to determine the accuracy of automatically identifying the user’s sitting position by applying five different machine learning methods (Support Vector Machines, Multinomial Regression, Boosting, Neural Networks, and Random Forest). Forty-one subjects were requested to sit four times in seven different prescribed sitting positions (total 1148 samples). Sixteen force sensor values and the backrest angle were used as the explanatory variables (features) for the classification. The different classification methods were compared by means of a Leave-One-Out cross-validation approach. The best performance was achieved using the Random Forest classification algorithm, producing a mean classification accuracy of 90.9% for subjects with which the algorithm was not familiar. The classification accuracy varied between 81% and 98% for the seven different sitting positions. The present study showed the possibility of accurately classifying different sitting positions by means of the introduced instrumented office chair combined with machine learning analyses. The use of such novel approaches for the accurate assessment of chair usage could offer insights into the relationships between sitting position, sitting behaviour, and the occurrence of musculoskeletal disorders., BioMed Research International, 2016, ISSN:2314-6133, ISSN:2314-6141

Objective The aim of this study was to determine and verify the optimal location of the motion axis (MA) for the seat of a dynamic office chair. Background A dynamic seat that supports pelvic motion may improve physical well-being and decrease the risk of sitting-associated disorders. However, office work requires an undisturbed view on the work task, which means a stable position of the upper trunk and head. Current dynamic office chairs do not fulfill this need. Consequently, a dynamic seat was adapted to the physiological kinematics of the human spine. Method Three-dimensional motion tracking in free sitting helped determine the physiological MA of the spine in the frontal plane. Three dynamic seats with physiological, lower, and higher MA were compared in stable upper body posture (thorax inclination) and seat support of pelvic motion (dynamic fitting accuracy). Spinal kinematics during sitting and walking were compared. Results The physiological MA was at the level of the 11th thoracic vertebra, causing minimal thorax inclination and high dynamic fitting accuracy. Spinal motion in active sitting and walking was similar. Conclusion The physiological MA of the seat allows considerable lateral flexion of the spine similar to walking with a stable upper body posture and a high seat support of pelvic motion. Application The physiological MA enables lateral flexion of the spine, similar to walking, without affecting stable upper body posture, thus allowing active sitting while focusing on work.

El incremento de la cantidad de trabajadores de oficina ha conllevado a un aumento del tiempo que se pasa en postura sedente de manera continua; por tal razón, esta condición de trabajo ha sido investigada con el propósito de comprender las manifestaciones de dolor o incomodidad resultantes de hacer trabajos en dicha demanda postural. Objetivo: comparar los datos basales de percepción de incomodidad debida al dolor lumbar con aquellos en función del uso prolongado de la silla, en presencia (CB) o no (SB) de variaciones en la inclinación del asiento. Materiales y métodos: se incluyeron diez trabajadores de oficina; se les asignó la silla modificada o estándar para uso continuo en la jornada laboral durante ocho meses, con seguimiento mensual mediante la medición de incomodidad con la Escala análoga visual. Los datos se analizaron de manera descriptiva y mediante métodos estadísticos, según la distribución de cada conjunto de datos. Resultados: revelan diferencias significativas y una potencial ventaja de la silla CB frente a la silla SB, de acuerdo con la comparación de medias de los reportes de incomodidad en la región lumbar (p=0,04). Además, se encontró que los trabajadores que recibieron intervención ergonómica en la oficina redujeron el aumento de incomodidad en la jornada laboral y el período de seguimiento, comparado con el grupo control. Conclusiones: las variaciones en la inclinación del asiento realizadas en forma dinámica y continua durante lapsos largos (silla dinámica CB) influyen de manera positiva en la disminución de la percepción de incomodidad en trabajadores de oficina. The increase in the amount of office workers, has led to an increase on the continuous time they expend in a sitting posture. Hence, this working situation has been investigated to understand pain or discomfort manifestations under this postural demand. Objective: to compare the basal data of discomfort perception due to back pain with those related to the extended use of chairs, when there is presence (or absence) of seat tilt variations. Materials and methods: the study involved a group of ten office workers. This subjects used a typical office chair (SB chair) or a modified one (CB chair) when they were at work. Then, there was a monthly evaluation of the discomfort using a Visual Analog Scale, during an eight months survey time. Data was descriptively analyzed using statistical methods, depending on the distribution of each data set. Results: revealed potential advantage of CB chair over the SB chair, considering the average comparison of discomfort in the lumbar region (p=0,04). In addition, workers receiving office ergonomic intervention reduced their daily discomfort during the monitored period, compared with the control group. Conclusion: dynamic and continuous variations of seat tilt during long periods of time have a positive influence in reducing the perception of discomfort in office workers. incremento da quantidade de trabalhadores de escritório, tem levado a um aumento do tempo que se passa em postura sedentária de maneira contínua, por este motivo, esta condição de trabalho tem sido investigada com o propósito de compreender as manifestações de dor ou incomodidade; resultado de realizar trabalhos em dita demanda postural. O objetivo do estudo foi comparar os dados basais de percepção de incomodidade devida à dor lombar com aquelas em função do uso prolongado da cadeira, em presença (CB) ou não (SB) de variações na inclinação da cadeira. Para isto, incluíram-se 10 trabalhadores de escritório, atribuindo-lhes uma cadeira modificada ou standard mensal mediante a medição de incomodidade com a Escala Análoga Visual. Os dados analisaram-se de maneira descritiva e mediante métodos estatísticos, segundo a distribuição de cada conjunto de dados. Os resultados revelaram diferenças significativas e uma potencial vantagem da cadeira CB gente à cadeira SB, tendo em conta a comparação de medias dos reportes de incomodidade na região lombar (p=0,04). Para além, se encontrou que os trabalhadores que receberam intervenção ergonómica no escritório, reduziram o aumento da incomodidade na jornada laboral e do período de seguimento, comparado com o grupo controle. Conclui-se, que as variações na inclinação da cadeira realizadas em forma dinâmica e contínua durante longos períodos de tempo (cadeira dinâmica CB), influem de forma positiva na diminuição da percepção de incomodidade em trabalhadores de escritório.

The studies of office chair constructions have identified differences in perception of comfort provided by different types of seats. Four seat constructions and the comfort provided to the users were compared by means of subjective indicators. After a two-day sitting on each of the studied chairs, the subjects scored their perception of comfort and discomfort, using the questionnaire with 17 statements. Unlike most similar studies, subjects evaluated seats on their own work places and in the environment to which they are accustomed. Constructional forms of the seat and materials that contributed more to the sense of comfort by minimizing fatigue and pains developed by sitting were determined. Results have shown that the chair with a net is significantly more comfortable than other chairs. The chair with molded PU foam is significantly more comfortable than the chair with springs, but statistically it does not differ significantly from the chair with slabstock PU foam. It has been concluded that the chair with a net got higher scores, which might be attributed to its frame construction and the absence of a hard base under the sitting surface., Istraživanjem konstrukcija uredskih stolica utvrđene su razlike u osjećaju udobnosti sjedenja na različitim sjedalima. Uspoređene su četiri konstrukcije sjedala i njihove udobnosti za korisnika, i to na temelju subjektivnih pokazatelja. Ispitanici su nakon dvodnevnog sjedenja na stolici ocjenjivali osjećaj udobnosti ili neudobnosti odgovarajući na upitnik sa 17 ponuđenih tvrdnji. Za razliku od većine sličnih istraživanja, ispitanici su ocjenjivali sjedala na svojim radnim mjestima i u okolini na koju su naviknuli. Ispitivanjem su određeni konstrukcijski oblik sjedala i materijali izrade stolica koje pridonose osjećaju veće udobnosti time što minimaliziraju osjećaj zamora i pojavu bolova pri sjedenju. Rezultati su pokazali da je stolica s mrežom znatno udobnija od ostalih. Stolica s hladno lijevanom PUR spužvom mnogo je udobnija od stolica s oprugama, ali se statistički ne razlikuje od stolica s rezanom PUR spužvom u sjedalu. Zaključeno je da je stolica s mrežom najbolje ocijenjena zbog njene okvirne konstrukcije i zato što ispod površine za sjedenje nema tvrde podloge.

Literature on seat comfort recognizes that seat interface pressures are the objective comfort measures that most clearly relate to users’ comfort perceptions about sitting experience. In this paper, the above relationship is quantitatively investigated by performing simple but effective explorative analyses on seat comfort data collected during experimental sessions involving 22 volunteers who tested 4 office chairs (differing in terms of cushion softness). Statistical data analyses show that subjective sitting comfort/discomfort ratings are significantly related to several combinations of pressure variables. The joint analysis of synthetic indexes based on seat interface pressures reveals to be a useful tool for comparative seat comfort assessment. Besides valuable suggestions for the definition of an effective strategy for seat comfort assessment, the results of data analyses provide useful information to support the product design phase. In fact, the sitting experience results to be significantly improved by: (1) a balancing of pressures between the bilateral buttocks; and (2) a balancing of contact areas between buttocks and thighs.

Measurement method and model method are adapted to analyze harmonious relations between people in the sedentary state and office chairs in various parts by starting from human design perspective of the product and using ergonomics knowledge. The research aims to settle down the technical problems which related to design fitness by correctly applying the ergonomics theory. During design process should study and summarize the user-friendly design elements of health office chairs, methods and performance evaluation as well.

Copyright © 2012 Elsevier Inc. All rights reserved. According to the affect program theory of facial displays, the evolutionary core of the human emotion system consists of a small set of discrete emotion mechanisms that comprise motor programs for emotion-specific facial displays. However, research on surprise has found that surprising events often fail to elicit the associated facial expression (widened eyes, raised eyebrows, mouth opening). The present study tested a refined Darwinian account of the facial expression of surprise, according to which surprising events cause widened eyes and raised eyebrows if they exceed the field of vision, as these facial changes increase the visual field and facilitate visual search. To test this hypothesis, we staged a surprising event that engulfed the field of vision: When the participants left the laboratory, they unexpectedly found themselves in a new room, a small chamber with bold green walls and a red office chair. In addition, to explore the role of social context for the expression of surprise, in two of three experimental conditions, a stranger or a friend they had brought to the experiment was sitting on the chair. The results provided no support for the Darwinian account of the facial expression of surprise. A complete expression of surprise was observed in 5% of the participants, and the individual components of the expression were shown only by a minority, regardless of social context. These findings reinforce doubts about the adequacy of affect program theory for the case of surprise.

Low back pain (LBP) is a common musculoskeletal disorder and prolonged sitting often aggravates LBP. A novel dynamic ergonomic chair ('Back App'), which facilitates less hip flexion while sitting on an unstable base has been developed. This study compared lumbar posture and trunk muscle activation on this novel chair with a standard backless office chair. Twelve painfree participants completed a typing task on both chairs. Lumbar posture and trunk muscle activation were collected simultaneously and were analysed using paired t-tests. Sitting on the novel dynamic chair significantly (p0.05) reduced both lumbar flexion and the activation of one back muscle (Iliocostalis Lumborum pars Thoracis). The discomfort experienced was mild and was similar (p0.05) between chairs. Maintaining lordosis with less muscle activation during prolonged sitting could reduce the fatigue associated with upright sitting postures. Studies with longer sitting durations, and in people with LBP, are required.Sitting on a novel dynamic chair resulted in less lumbar flexion and less back muscle activation than sitting on a standard backless office chair during a typing task among pain-free participants. Facilitating lordotic sitting with less muscle activation may reduce the fatigue and discomfort often associated with lordotic sitting postures.

Consumers’ product style perceptions and preference are vague and uncertain. In order to identify consumers’ needs more accurately, this paper established a questionnaire based on fuzzy data, carried out a spot check to consumers’ style preference and perceptions of twelve office chairs with typical form style, then conducted the mean, distances calculation and fuzzy clustering analysis by Excel, SPSS, and Matlab. Comparing with statistics results of traditional questionnaire data, this paper points out that fuzzy data statistics are suitable for the mean calculation of small sample and the clustering algorithm of few preference variables.

Thermal comfort is related to human physiological reactions. In order to maintain a constant internal temperature, the human body must dissipate heat in a warm climate, and prevent heat losses in a cold climate. The overall sensation of comfort accompanies the warmest part of the body in a warm environment and the coldest one in a cold environment. Chair design and clothing may affect the difference in sensitivity between certain parts of the body, that is, they may affect thermal comfort. This research focused on subjective sensation of warmth and moisture while sitting on offi ce chairs. The subjective method of evaluating thermal discomfort is based on ISO7730:2005 standard, according to which a questionnaire was made for this research. Six subjects took part in the research. They were sitting on fi ve different offi ce chairs as they performed their usual jobs in controlled conditions. From the point of view of the evaluation of the sensation of warmth, all chairs were evaluated neutrally. The sensation under the buttocks and thighs was reported to be somewhat warmer, while the sensation on the back was reported to be somewhat colder, which was affected by the design of the back of the chair. No correlation has been proven between the actual temperature and moisture measurements and subjective evaluations of thermal comfort, in spite of a number of direct links. The use of the present method offers the possibility of further research into this subject, which would prove more thoroughly a correlation between design and construction solutions of office chairs and the comfort perceived by sitting persons.

Gender differences in lumbar and pelvic posture have been reported previously in prolonged sitting, both in an office chair and automobile seat. To date, it is not known whether these postural exposures during prolonged driving affect the passive lumbar spine flexion stiffness. The purpose of this study was to examine time-varying responses of passive lumbar spine stiffness, lumbar spine and pelvic postures during a 2 h simulated driving trial. Secondary goals investigated the influence of gender on lumbar spine stiffness, discomfort scores and seat pressure profiles. Twenty (10 males, 10 females) subjects were recruited to complete a 2 h simulated driving task. Passive lumbar range of motion was measured on a customized frictionless jig before, halfway through and at the end of 2 h. During driving there was a time-varying difference in the lumbar flexion angles adopted by the gender groups. A significant interaction ( p = 0.0458) was found for gender and time with women being found to sit significantly different than males in the second hour of driving exhibiting greater maximum lumbar flexion (60.0% ROM (±1.27) than men 50.0% ROM (±1.5). Both men and women demonstrated similar passive stiffness changes characterized by an initial increase in transitional zone stiffness after 1 h (+0.1 Nm/degree for males and +0.3 Nm/degree for females, p = 0.2372). Over 2 h of driving there was a non-significant trend of genders to respond differently to the seated exposure. Specifically transitional zone stiffness was found to increase in males (0.86 (SD 0.31) to 0.92 (SD 0.31) Nm/degree) and decrease in females (0.81 (SD0.88) to 0.73 (SD 0.52) Nm/degree) ( p = 0.1178). Differences in lumbar posture and passive stiffness over 2 h of simulated driving were demonstrated between genders in this study. Relevance to industry Gender specific ergonomic interventions should be investigated for the automobile seat. Additionally, the changes in passive stiffness induced by prolonged seated exposures could introduce altered low back kinematics in activities performed after a long car ride. Lifting scenarios such as luggage unloading or parcel delivery are common activities immediately after driving. The altered stiffness of the lumbar spine in these activities could have potential ergonomics and injury related implications for both the general population and professional drivers.

This paper proposed a design of the office chair with multi fitness function (multi-functional office chair for short) which can mainly achieved comfortably office; adjust the reline angle, doing fitness activities, such as stretched movement, kicking motion, sit-ups and so on. It not only satisfies the needs of people's daily work, rest and fitness exercise, but also meets the design requirements of ergonomics.

Modular design methodology is a very important design methodology that allows production of the maximal types of products with the minimal types of components and extending the components’ compatibility to different types of products to satisfy a variety of customers. However, existing modular design methods do not consider customers’ adaptability for products requiring physical interaction between different parts of body and product components. Our study proposes a modular design methodology from the perspective of maximum customer satisfaction considering physical interaction between human and product. Modular design of office chair is chosen as a case study to develop a modular design methodology for products with improved adaptability for customers of various body sizes. The proposal consists of customer requirement analysis, modularization, and modularization assessment procedure. Also the proposal includes a method to determine size variation of defined modules at the detail product design stage for mass customization.

Background context Sitting is frequently assumed to cause high spinal loads because people with sedentary work often suffer from low back pain. It is assumed that the posture while sitting, as well as several seat parameters, also affects the spinal loads. Purpose To measure the loads on a spinal implant for different upper body inclinations, backrest declinations, seat heights, types of seat, and arm positions. Study design Loads on a vertebral body replacement during sitting were measured in five patients with telemeterized implants. Methods The telemeterized vertebral body replacement measures all six load components. It was implanted into five patients suffering from compression fractures of a lumbar vertebral body. Loads were measured when the patients were sitting on a stool and inclining their upper body between 15° flexion and 10° extension in steps of 5°; on a chair with an adjustable backrest that allowed declination angles between 108° and 180°; on an office chair while the seat height was varied between 40 and 60 cm in steps of 5 cm; and successively on seven different types of seats. The effect of the arm position was also studied. Results The resultant implant force was increased on the average by 48% for 15° flexion and decreased by 19% for 10° extension of the trunk. When sitting on a chair with an adjustable backrest, the loads decreased with an increasing backrest declination angle. The seat height had in most cases only a minor effect on implant loads. In comparison to sitting on a stool, the loads were reduced when sitting on a bench (7%) or a stool with a padded wedge (9%), a knee stool (19%), a chair (35%), and an office chair (41%). Sitting on a physiotherapy ball increased the loads by 7%. Placing the hands on the thighs reduced the implant loads on the average by 19% in comparison to arms hanging on the sides. Conclusion Spinal loads can be reduced by leaning against the backrest, placing the arms on the armrest or the thighs, and by decreasing the flexion angle of the upper body.

A regular office chair was equipped with force transducers, which allow to monitor and to guide the sitting behavior of a person during an office working day. Only four force transducers are required to estimate characteristic parameters for quantifying the biomechanical effect of a certain sitting posture. Based on these parameters, which rely on a simple biomechnical model, a posture cost function was proposed for classification of the sitting posture. Since for posture guidance the posture control system has to be known, a simple approach for identification of the controller parameters is proposed. A framework for designing effective exercises is presented and allows to assess different exercises for improving the person's sitting behavior. The proposed sensor concept of the chair as well the proposed biomechanical model are evaluated by means of laboratory experiments.

With increasing living standards, a modern product is required to provide emotional links between a user’s personality and their work environment, in addition to satisfying functional and physiological needs. Since office workers in Taiwan have average daily working hours of over 8 h, they spend lots of time on office chairs, and nowadays more companies are willing to buy good chairs so that their employees can deliver higher efficiency under a more comfortable office environment. After interviewing a group of experts, office chairs are classified into 7 types, and the participants’ personality traits are classified into 4 categories. The influence of different personality traits on the evaluation of office chairs by attractiveness is analyzed by quantification theory type I. Design elements that can better deliver an office chair’s attractiveness are determined. The results allow future designers to improve their designs by identifying the preferences of target users under difference office scenarios.

Haptic-aided design (HAD) involves the use of a haptic simulator in place of physical prototypes in the design and development of products with which human beings interact physically. The development time and cost can be significantly reduced by adopting this HAD scheme. Although both physical and emotional factors are equally important, only the emotional factors were taken into consideration in the previous HAD process. Consequently, the design of the products was sometimes unsatisfactory from the viewpoint of ergonomics, even though users were emotionally satisfied with the products. To overcome this problem, in this study, we propose a new human-oriented design methodology that is enhanced by taking the physical factors into consideration. The HAD scheme was verified by using a haptic chair simulator to design a tilt mechanism of an office chair for which the stiffness of the backrest can be adjusted; then, the design was simulated using MADYMO. The results show that the proposed method can reflect both the physical and emotional factors to modify the design in real-time.

Office employees are exposed to acoustic noise, especially in an open office environment. Passive or active headsets sufficiently reduce the level of noise, but their long-time wear is uncomfortable. The paper presents an active headrest system built into a chair. Feedforward control is utilized with multiple reference microphones, and flexible gooseneck microphones serve as error sensors. The reference sensors surround the chair, allowing the suppression of sound waves arriving from any direction. The concept of multiple reference control has been tested by extensive experiments showing that multiple reference signals help to increase the suppression in normal rooms where reverberation occurs, even if only one noise source is present. The preliminary experiments are completed by a series of simulations aiming to explore the zones of quiet at the user&rsquo, s ears. The paper introduces the construction details of the noise-canceling chair: The two loudspeakers are controlled by the signals of two error microphones and four reference signals. The controller is based on the normalized filtered error least mean squared algorithm, implemented on an Analog Devices ADSP-21262 signal processor-based hardware. Experimental results are reported that show the efficient suppression of tonal, as well as broadband disturbances.

초록:본논문에서는사무용의자의틸트동작시요추지지기능과등의미끄럼을평가함으로써등판회전중심의최적위치를연구하였다.이를위해인체와의자로이루어진수학적모델을이용하여틸트동작시뮬레이션을수행하였다.착석된인체모델의측면상에서고관절중심을포함한42개의위치에등판회전축위치를설정하고각각시뮬레이션을수행하였다.또한등판의회전중심이고관절에위치한의자시작품과좌판하부에위치한기존의의자에대해동작분석실험도함께수행하였다.시뮬레이션결과등판의회전중심이고관절중심에가까이위치할수록틸트시요추각도변화량과등의미끄럼거리는작아졌다.한편실험결과착석자의등과등판사이의이격변위와미끄럼변위는등판의회전중심이고관절위치에설계된시작품에서더작게측정되었다.시뮬레이션과실험결과로부터등판의회전중심이인체의고관절위치에가깝게설계되면틸트시착석자의요추를효과적으로지지해줄수있음을알수있었고이때착석자는보다편안하고건강한착석자세를유지할수있다.이결과는사무용의자에서등판회전축위치의인간공학적설계를위한가이드라인을제공한다.Abstract:Inthisstudy,theoptimalpositionforthebackrestpivotofanofficechairwasinvestigatedbyevaluatingitsperformanceintermsofthelumbarsupportandslidingdistanceofthebackfromthebackrestduringtiltingmotions.The simulation was performed using a mathematical model, which included a human body and a chair. Forty-twobackrestpivotpointswereselectedonthesagittalplanearoundthehipjointofasittingmodel.Amotionanalysisstudywasalsoperformedusingaprototypeofanofficechair(A-type)withabackrestpivotlocatedonthehipjointofanormalKoreanmodelandatypicalofficechair(B-type)withitspivotlocatedundertheseat.Thesimulationresultsshowedthatboththelordosisangleandtheslidedistanceofthebackwereminimizedwhenthebackrestpivotwas positionedclosetothe hipjoint. Theexperimental results showedthat theslidedistanceandgapbetweenthesitter'slumbarandthebackrestwassmallerwiththeA-typethantheB-type.Basedonthesimulationandexperimentalresults,itcanbeconcludedthatthebackrestcansupportthesitter'slumbarareamoreeffectivelyasthepivotpositionfor reclining approaches closer to the hip joint. In this position, the sitter can maintain a comfortable and healthysitting posture. This paper presents the methods and guidelines for designing an office chair with ergonomicconsiderations.