Seating COMFORT AND DISCOMFORT
The Cambridge Advanced Learner 's lexicon ( 2008 ) defines comfort as a pleasant feeling of being relaxed and free from hurting. Hertzberg ( 1972 ) describes comfort as absence of uncomfortableness. The term `` place comfort '' is typically used to specify the short-run consequence of a place the human organic structure ( Kolich, 2008 ) . Comfort is a generic and subjective feeling that is hard to mensurate, construe, and related to human physiological homeostasis and psychological well being ( Shen and Parsons, 1997 ) . Seat comfort is a really subjective issue because it is the client who makes the concluding finding and client ratings are based on their sentiments holding experienced the place ( Runkle, 1994 ) . Helander ( 2003 ) stressed ergonomic remains in the place design, where good biotechnologies is a stipulation for comfort. By and large, comfort issues non under argument by research workers are ( De Looze et al. , 2003 ) : ( 1 ) comfort is a concept of a subjectively-defined personal nature ; ( 2 ) comfort is affected by factors of assorted nature ( physical, physiological, psychological ) ; and ( 3 ) comfort is a reaction to the environment. Helander and Zhang ( 1997 ) describes that there is a difference between comfort and uncomfortableness during sitting in office chair. They discuss that comfort is more related to emotional facets like experiencing safe and luxury. Discomfort is more related to physical facets like feeling force per unit area and musculus hurting.
2.2.1 The Theoretical Model of Comfort and Discomfort
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The constructs of comfort and uncomfortableness in sitting are under argument. There is no widely accepted definition, although it is beyond difference that comfort and uncomfortableness are feelings or emotions that are subjective in nature ( De Looze et al. , 2003 ) . Seating uncomfortableness has been examined from a figure of different positions. The job with measuring comfort in respects to coerce or any other factor is that, comfort is subjective and non easy to quantify. Seating uncomfortableness varies from capable to capable and depends on the undertaking at manus. Comfort, nevertheless, is a obscure construct and subjective in nature. It is by and large defined as deficiency of uncomfortableness ( Shen and Vertiz, 1997 ) . One of the definitions of comfort by Dumur et Al. ( 2004 ) is the pleasant and fulfilling feeling of being physically or mentally free from hurting and agony, or something that provides this feeling.
Harmonizing to the 'European Union Legislation for Drivers and Promote ' ( Euroactiv, 2007 ) , the hebdomadal drive clip for truck drivers shall non transcend 56 hours. Commercial trucks are alone in that they are specifically designed to transport heavy tonss over long distances. The drawn-out period of sitting includes higher hazard of back jobs, numbness and discomfort in the natess due to excessively high surface force per unit area under the thighs ( Floyd and Roberts, 1958 ) . The survey by Adler et Al. ( 2006 ) shows that the driver position is non inactive and alterations over clip. Position alterations and uninterrupted gesture are schemes of the driver to avoid mechanical burden and ischaemia of tissue, which has been identified as one chief ground for uncomfortableness. Discomfort feelings, as described by Helander and Zhang ( 1997 ) , is affected by biomechanical factors and weariness. The beginnings of such uncomfortableness are listed in Table 2.1.
Table 2.1 Causes of siting uncomfortableness ( Helander and Zhang, 1997 ) .
Human experience manner
Shock absorber stiffness
Zhang et Al. ( 2006 ) presented a theoretical account that illustrates the interaction of comfort and uncomfortableness as shown in Figure 2.1. Passage from uncomfortableness to comfort and frailty versa are possible in the intersection of the axes. Hence, if uncomfortableness is increased, such as with a longer clip within undertaking and weariness, comfort will diminish. Its agencies that good biomechanics may non increase the degree of comfort, it is likely that hapless biomechanics turns comfort into uncomfortableness.
Well Being and
Figure 2.1 Hypothetical Model of Discomfort and comfort ( Zhang et al. , 2006 ) .
Millet and Pignede ( 2001 ) described the comfort methodological analysis, where is to avoid introducing with a comfort mark and burying other facets. They have explained that when interior decorator make a great betterment on a specific facet of comfort and if, at the same clip, the interior decorator induce a job for another comfort facet, the consequence is the uncomfortable place. They besides defined their `` comfort oval '' as shown in Figure 2.2.
Figure 2.2 The 10 points of comfort ( Millet and Pignede, 2001 ) .
Kolich ( 2008 ) described that seats are required to fulfill culture-based penchants and outlook of place comfort. For illustration, the Western European, by and large, are thought to prefer firmer seats as compared to North Americans. The writer besides visualized the factors that impacting automobile place comfort as in Figure 2.3.
Figure 2.3 Factors impacting subjective perceptual experiences of car place comfort ( Kolich, 2008 ) .
Position as described by Kolich ( 2008 ) , is the most of import single factor. While the consequence of position is assumed to be important, it is hard to turn to because residents with similar anthropometric features may sit in wholly different organic structure places. Stiffness, geometry, contour, breathability, and titling are considered seat factors. Stiffness refers to the resilience of the place system. Geometry defines place form in footings of breadth, length, and tallness, whereas contour trades with the profile of the sitting surface ( e.g. location and prominence of lumbar vertex ) . The place 's geometry and contour must suit the anthropometry variableness of the mark population. Breathability, as it pertains to the soft trim ( i.e. foam denseness and fabric building ) , may impact car place comfort in utmost environmental conditions. Styling must be included as a place factor because aesthetic quality may impact perceptual experiences of comfort, in the same manner as nameplate or purchase monetary value of vehicle. Runkle ( 1994 ) described the Lear 's place comfort benchmarking methodological analysis which incorporates and integrates four tools into a individual comprehensive place comfort analysis ; market research surveies, benchmarking surveies, organic structure force per unit area distribution analyses and human factors surveies of anthropometric informations. The consequences concluded that good aesthetics, well-designed and comfy are more of import than physical parametric quantities in a place design.
De Looze et Al. ( 2003 ) proposed a theoretical account of siting comfort and uncomfortableness as shown in Figure 2.4. The left side of the theoretical account is about the seating uncomfortableness. At the human degree, the 'exposure ' , 'dose ' . 'response ' and 'capacity ' is the chief issues of the work-related physical ailments. The external exposure factors bring forthing a perturbation of the internal province ( dose ) of an person. The dosage may arouse a cascade of mechanical, biomechanical or physiological response. The extent to which external exposure leads to an internal dosage and responses, depends on the physical capacity of the person. The loading factor of a sitting individual caused by the physical features of the office place, the environment and the undertaking. These external tonss related to muscle activation, internal force, intra-discal force per unit area, nervus and circulation inclusion, and tegument and organic structure temperature rise, arousing farther chemical, physiological and biomechanical responses. The right side is concerns comfort, such as feelings of relaxation and wellbeing. In the theoretical account, the physical and psycho-social factors such as occupation satisfaction and societal support are playing a function at context degree. At the place degree, aesthetic design and physical characteristics may impact the feelings of comfort. At human degree the influential factors are assumed to be single outlook and other single feelings or emotions.
Figure 2.4 Theoretical theoretical account of comfort and uncomfortableness and its implicit in factors at the human, place and context degree ( De Looze et al. , 2003 ) .
2.3 Aircraft Passenger Seat
World market has become really competitory in the concern and premiere category sections as this tend to give higher net income border in comparing with the economic system whose borders have been undercut by the new low-priced air hoses. The reaching of the new flourishing economic systems of China and India and the bing tiger economic systems pushed the demand for concern travellers on long draw flights really high. The air hoses responded by offering new degree of comfort and edification. The aircraft place maker have designed and manufactured the aircraft rider to guarantee the safety and comfort during air travel ( SEAT, 2006 ) .
2.3.1 Current Aircraft Passenger Seat
Swiss based company designed the air-filled chamber to replace the conventional froth. Pneumatic shock absorbers adjust automatically to siting and kiping places with air Chamberss. Due to the adaptative constructions of air chamber, riders feel no force per unit area points and can set shock absorber soundness separately ( Lantal Textiles, 2010a ) . Since 2009, all concern and first category seats of the SWISS long-haul fleet were equipped with Lantal 's advanced pneumatic comfort system. It sets new criterions in rider comfort and has a direct impact on the profitableness of air hoses. Four place companies, viz. , B/E Aerospace, Contour, ZIM Flugsitz and Recaro implemented Lantal 's pneumatic comfort system in their aircraft place ( Lantal Textiles, 2010b ) . The Lantal 's pneumatic comfort system is a inactive control system, where rider needs to set the hardness of air chamber manually.
Thompson Solutions developed new economic system place, the Cozy Suite. The Cozy Suite provides each rider with two armrests. The place is designed to assist aircraft rider to kip. It has contoured shoulder country and offers wider articulatio genus infinite compared to standard siting designs of the same pitch. It besides features a alone hands-free, tip-up place base, which makes it easier to acquire in and out of window seats, and aid to diminish embarkation and deplaning times ( James and Kington, 2008 ) . The new place design claimed to increase 14 % of economic system category rider seats in Boeing B767-400. The Cozy Suite focused on legroom, armrests, air hoses gross, place measure, easiness of emersion, personal infinite and dedicated kiping country ( Thompson Aero Seating, 2009 ) .
B/E Aerospace exhibited its economic system category 'Spectrum ' rider place. The new platform is 10 % igniter in weight and provides over 14 % extra life infinite. The developed place includes a graven Crytalflex back support system and meets the 2009 Head Injury Criteria ( HIC ) demands. Recaro Aircraft Seating presented a new version of its single-beam Comfort Line 3610 economic system category place. The place increases the legroom even at a comparatively short place pitch. The new place have comfort characteristics include kinematics that improve the seating angle, a flexible head restraint, a foot cyberspace and ultra-thin visible radiation lightweight aluminum backrest with comfort gauze ( James and Kington, 2008 ) .
Air New Zealand introduced the 'Skycouch ' , a lie-flat economic system and premium economic system place in twelvemonth 2010. The 'Skycouch ' is a specially designed row of three seats, has been engineered to make a lie-flat, flexible infinite all the manner to the seat-back in forepart, supplying a topographic point for the childs to play, or the holy grail of economic system travel- a level surface for grownups to loosen up and kip ( Air New Zealand, 2010 ) .
Based on the survey on current aircraft rider place development from twelvemonth 2008 to 2010, the aircraft place makers and airliners were focused on the igniter and dilutant place every bit good as more seats to set in the cabin.
2.4 EXISTING NECK SUPPORT DURING TRAVEL
2.4.1 Travel Type Neck Support
From the merchandise hunt utilizing web services, several cervix supports related merchandises were found. There are different types of cervix supports that used during air travel such as inflatable cervix pillow ( Pilot Paul, 2010 ) , polyester filled pillow ( Pilot Paul, 2010 ) , memory froth pillow ( Pilot Paul, 2010 ) , feather filled pillow ( Nick Robinson, 2010 ) and the aircraft place with neck support ( Cathay Pacific, 2010 ; Qantas, 2010 ) .
Inflatable Neck Pillow
The inflatable cervix pillow can be found from any travel store at low monetary value. The chief job with inflatable cervix pillow is that they normally fail by developing a slow leak and upseting the user during remainder. The air inside the inflatable travel cervix pillow will spread out and contract the as the aircraft alterations altitude. This is because the cabin height alterations in proportion to the plane 's height. As the cabin height ascents, the air in the pillow expands. As the plane descends, it contracts. The pillow size alteration is relative to the height alteration. These cheap travel pillows seldom last more than two or three trips. The better 1s do last thirster. Another disadvantage of the less expensive air travel pillows is the vinyl stuff can acquire hot and gluey against your face. The chief advantage of inflatable travel pillows is that they take small room in your baggage. They are besides lighter than any of the other types, particularly the Polygonum fagopyrum 1s ( Pilot Paul, 2010 ) .
Memory Foam Travel Pillow
The memory froth travel pillow provides tonss of support and stabilisation and is highly comfy. A travel cervix pillow made with memory froth will last many old ages. It should last much longer than an inflatable or poly-filled one. Foam travel pillows do an first-class occupation of keeping your caput still therefore leting you to kip. Memory foam casts in response to your organic structure ' form, weight and heat to organize a pressure-free cradle of support. When user is non utilizing it, a froth travel cervix pillow compresses good to suit in your carry-on bag. They are comparatively lightweight. While memory froths travel pillows can be some of the most expensive among other neck support pillow ( Pilot Paul, 2010 ) .
Polyester Travel Pillow
The polyester travel pillow does non supply the support and stabilisation like memory froth or Polygonum fagopyrum travel pillows. Some air hose such as KLM and China Southern Airlines do provide polyester pillow in the cabin. The advantage of polyester travel pillow is low cost ( Pilot Paul, 2010 ) .
Feather Filled Pillow
The plume filled pillows are really soft, cuddly and fictile. The pillow contours to the caput and cervix sensible good and supply more support than down. The pillow can be scrunched to supply better support to user caput and cervix. The plume pillows weigh really small, normally weigh no more than a lb or two ( Nick Robinson, 2010 ) .
Feather pillows frequently do non keep important support throughout the dark because they tend to drop in to some grade. As a consequence, the user needs to set the pillow during remainder. And botching the pillow or agitating it may besides be required to return the pillow to its preferable loft. As the pillow ages, increased fluffing or shaking will be required. The difficult quills of the plumes can frequently be noticed through the instance and can even jab through. Further, the pillow creates crunching-like noise when the pillows are compressed because the plumes can incorporate difficult parts or because the pillow has a fictile bed to forestall the plumes from jabing through. Finally, plume pillows have been known on juncture to hold an olfactory property, possibly of H2O poultry or chemicals used to sanitise the plumes ( Nick Robinson, 2010 ) .
2.4.2 Long Distance Commercial Vehicle Passenger Seat with Neck Support
The Coach Passenger Seat with Neck Support
Long-distance manager services, besides called express coachs or interurban managers, have in common that they cater for conveyance demands outside urban agglomerations, normally from metropolis to metropolis, frequently besides functioning towns non good served by rail on their manner ( van de Velde, 2009 ) . The manager rider place is one of the of import characteristics to guarantee the comfort of the rider for long distance travel. For illustration, an express manager that travels from Singapore to Thailand as showed in Figure 2.5 was equipped with cervix and leg support for their rider comfort during long distance travel.
Figure 2.5 The luxury manager rider place with neck support ( Five Star Tours, 2010 ) .
The Train Passenger Seat with Neck Support
For the long distance high velocity rail, such as ICE, Thalys and Eurostar offered luxury rider place to guarantee the siting comfort of rider during train travel. German ICE offered the rider place with the cervix support as showed in Figure 2.6. The cervix support is a soft shock absorber that attached to the place with two strings. Thalys ( Figure 2.7 ) and Eurostar ( Figure 2.8 ) offered similar rider place with same side support for caput and cervix.
Figure 2.6 The German train ICE rider place with neck support.
Figure 2.7 The Gallic train Thalys rider place with neck support ( Raileurope, 2010 ) .
Figure 2.8 The Eurostar rider place with neck support ( Bembridge, 2007 ) .
The Aircraft Passenger Seat with Neck Support
The economic system category place of major air hoses such as KLM, Malaysia Airlines, Qantas Airlines and Cathay Pacific Airlines equipped with adjustable caput remainder to better the caput and cervix comfort during air travel. The headrest of economic system category place is a automatically device that support caput and cervix. The device needs to be adjusted manually by the rider for comfort betterment. The headrest ( Figure 2.9 ) that available in the economic system category aircraft place of Cathay Pacific Airlines able to adjusts in four ways - up, down and sideways ( with the adjustable ears ) . The head restraint is to maximise comfort and support for rider caput and cervix ( Cathay Pacific, 2010 ) . Subsequently, the Qantas A380 economic system category place besides equipped with the caput remainder 'wing ' for caput and cervix support ( Qantas, 2010 ) . Most of the headrest that available in current aircraft rider is a mechanical system where the rider needs to set the caput remainder manually to the needed place. Figure 2.10 showed the Qantas economic system category aircraft rider place.
Figure 2.9 The Cathay Pacific Airlines economic system category aircraft place with constitutional cervix support ( Cathay Pacific, 2010 ) .
Figure 2.10 The Qantas Airline economic system category aircraft place with neck support ( Travelhouseuk 's Travel Blog, 2010 ) .
2.5 OBJECTIFYING AND SUBEJCTIFYING OF SEAT ( DIS ) Comfort
2.5.1 Relationship of nonsubjective measurings to siting comfort and uncomfortableness
The design of vehicle 's seating for improved drive uncomfortableness is one of the primary ends for vehicle makers. Comfort measuring is hard because of such factors as user subjectiveness, occupant anthropometry, place geometry, and sum of clip spent sitting ( Thakurta et al. , 1995 ) . A great trade of research has been performed in recent old ages to happen nonsubjective steps for foretelling place comfort perceptual experience. Some of the proposed nonsubjective steps include quiver, interface force per unit area, and musculus activity. These nonsubjective steps are correlated with subjective informations to find the comparative effects of each step related to comfort ( Nawayseh and Griffin, 2005 ) . Research has shown that some of the chief factors that affect siting comfort are seat-interface force per unit area distribution, whole-body quiver and force per unit area alteration rate ( Boggs, 2004 ) .
Temperature and Humidity
A huge bulk of nonsubjective steps used for measuring comfort and uncomfortableness. From the literature hunt, the nonsubjective measuring methods for place such as force per unit area distribution, position, computer-aided design ( CAD ) , computer-aided technology ( CAE ) , temperature, humidness, quiver, electromyography ( EMG ) , and epinephrine. Figure 2.11 shows an overview of different nonsubjective measuring methods for place comfort and uncomfortableness.
Figure 2.11 Overview of different nonsubjective measuring methods for place comfort and uncomfortableness.
From the literature hunt utilizing computerized systems such as ScienceDirect, force per unit area measuring is used to analyze the uncomfortableness feeling among the drivers. Pressure measuring method is the most used method for the place developer to mensurate the comfort and uncomfortableness of sitting individuals ( Adreoni et al. , 2002 ; Boggs, 2004 ; Lee et al. , 1988 ; Nawayseh and Griffin, 2005 ; Yun et al. , 1992 ) . The instruments that used in force per unit area measuring, viz. , force per unit area mat, force per unit area proctor system, force detector, place distortion mensurating device and force per unit area imagination system.
The automotive industry strongly encourages research in the field of nonsubjective comfort appraisal, particularly dedicated to the place and the related positions ( Bustrom et al. , 2006 ; Scarlett et al. , 2007 ) . Driver position is one of the of import issues to be considered in the vehicle design procedure ( Wu and Chen, 2004 ) sing non merely the auto and the user ( Kolich et al. , 2006 ; Schust et al. , 2006 ) but besides the experimental conditions. The instruments that used in the position measuring are camera, optoelectronic system ( Andreoni et al. , 2002 ; Brazier et al. , 2002 ) driving position monitoring system, digital signal processing, supersonic device ( Brazier et al. , 2002 ; Park et al. , 2000 ) , 3D gesture analysis ( Park et al. , 2000 ) , and gesture measuring system ( Bush and Phaeda, 2003 ) .
A major part of the quivers experienced by the residents of an car enters the organic structure through the place ( Choi and Han, 2003 ) . Whole-body quivers, which are perpendicular quivers, tend to impact the human organic structure the most. These quivers are transmitted to the natess and dorsum of the resident along the vertebral axis via the base and dorsum of the place ( Wereley and Choi, 2005 ) . The instruments that used are perpendicular quiver simulator, angulator rate detector, accelerometer and whole organic structure quiver measuring. Six surveies have used computer-aided technology ( CAE ) methods to mensurate the sitting individual comfort such as finite component method ( Choi et al. , 2007 ) , practical world ( Marler et al. , 2007 ) , simulation method ( Kolich and White, 2004 ; Seitz et al. , 2005 ; Verver et al. , 2005 ) and unreal intelligence technique ( Kolich et al. , 2004 ) .
Other surveies for nonsubjective measurings are related to human physiology. The physiology of human such as encephalon, musculus, bosom, tegument and spinal can be used to mensurate the sitting individual comfort or uncomfortableness degree. The spinal burden measurings have been performed in two surveies. Five surveies are carried out to mensurate the tegument temperature and humidness degree. Two surveies utilizing electromyography ( EMG ) to mensurate the musculus reaction in relation with the capable uncomfortableness feeling. There is a survey which used epinephrine content in the piss to mensurate the driver 's stress degree. Besides, the encephalon activity can be detected by electroencephalography ( EEG ) every bit good as O impregnation can be used to mensurate discomfort degree of sitting individual excessively.
Pressure Measurements: The force per unit area distribution method is the most common method that used by research workers to mensurate place comfort objectively. Several research workers have measured the force per unit area at the human-seat interface utilizing electronic detectors ( capacitive, resistive, strain gage ) , pneumatic and electro-pneumatic. However, the visco-elastic behaviour at the interface is wholly altered by the detectors used ( Nawayseh and Griffin, 2005 ) . Andreoni et Al. ( 2002 ) used force per unit area mat to garner shock absorber and backrest force per unit area informations during inactive conditions and existent drive activity. Gyi et Al. ( 1997 ) evaluated the place force per unit area measuring engineerings that used in the anticipation if driver uncomfortableness for assorted auto place designs, and supply interior decorators and makers with rapid information early in the design procedure. Lee et Al. ( 1998 ) recruited 100 topics and 16 seats to happen the correlativities between force per unit area informations and comfort. They stated that the correlativity is non high plenty to be the footing for any design determination. Yun et Al. ( 1992 ) studied the correlativity between force per unit area distribution and local uncomfortableness of auto seats. The consequence found that force per unit area distribution at the low back and buttock country was statically correlated to local uncomfortableness in auto seats.
There are huge bulk of nonsubjective steps used for measuring comfort. They were created based on the comparing of different place designs with similar types of place shock absorbers that are widely used in the automotive industry, i.e. urethane froth shock absorbers. The kineticss of air-inflated place shock absorbers is really different from that of foam shock absorbers in footings of their interface with the human organic structure. Further surveies should be performed to utilize alternate methods of rating that can efficaciously measure the kineticss at the interface between the shock absorber and the human organic structure. In add-on, the vehicle place interior decorator should see the soft tissue in contact with a soft place surface. Figure 2.12 shows the assorted force per unit area measuring techniques that used in the place development.
Ocular fibres device
SAE AM50 cheek signifier indentor
Talley force per unit area proctor system
Pressure feeling mat ( piezo resistive )
Highest extremum force per unit area measuring
Lower extremum force per unit area
( Pressure distribution )
Pressure and contact country measuring
Seat distortion mensurating device
( Strain gage )
Figure 2.12 Assorted force per unit area measuring techniques.
Position Analysis: The automotive industry strongly encourages research in the field of nonsubjective comfort appraisal, particularly dedicated to the place and the related positions ( Bustrom et al. , 2006 ; Scarlett et al. , 2007 ) . Driver position is one of the most of import issues to be considered in the vehicle design procedure ( Wu and Chen, 2004 ) sing non merely the auto and the user ( Kolich et al. , 2006 ; Schusr et al. , 2006 ) but besides the experimental conditions. Figure 2.13 shows the different nonsubjective measuring techniques for position analysis.
Driving position monitoring system ( DPMS )
Digital signal processing
Shock absorber lading indentor
Supersonic device of tactual exploration
Body motion measuring
3D optical maser scanning
3D co-ordinate measurement machine
( obesevation )
Motion measuring system
3D gesture analysis
Figure 2.13 Objective measuring techniques for position analysis.
Vibration Measurements: A major part of the quivers experienced by the residents of an car enters the organic structure through the place ( Choi and Han, 2003 ) . Whole-body quivers, which are perpendicular quivers, tend to impact the human organic structure the most. These quivers are transmitted to the natess and dorsum of the resident along the vertebral axis via the base and dorsum of the place ( Wereley and Choi, 2005 ) . Since the natural frequence for the human bole falls in the scope of 4-8 Hz, it is expected that the whole organic structure quivers that will most mostly affect riders will happen in this frequence scope ( Ofori-Boetang, 2003 ) . Figure 2.14 shows the nonsubjective measuring methods in quiver analysis.
Vertical quiver simulator
Angulator rate detector
Whole organic structure quiver measuring
Figure 2.14 The nonsubjective measuring methods for quiver analysis.
Temperature and Humidity Measurements: Thermal comfort is an of import facet to be considered in the biotechnologies rating of the driver seats, which are important interfaces between adult male and machine in car. Determining thermic comfort in vehicle is a complex undertaking, because thermic comfort involves the interaction of many variables and cars are susceptible to temporal fluctuations in their thermic environments ( Mehta and Tewari, 2000 ) . As shown in Figure 2.15, air velocity, air temperature, humidness and average beaming temperature are used to find the temperature and humidness of the place objectively.
Air velocity detector
Air temperature detector
Mean beaming temperature
Figure 2.15 The nonsubjective measuring methods for temperature and humidness.
Computer-aided Technology: Due to the promotion of the computing machine system, computer-aided technology ( CAE ) is used to back up scientists and applied scientists in undertakings such as simulation, analysis, design, industry, planning, diagnosing and fix. The usage of CAE could ease the place development procedure. In the early phases of the design procedure a new design can be tested for its grade of comfort by computing machine simulations with theoretical accounts of the human and the place. This allows makers to rush up the design procedure of a new place or interior and cut down costs. Verver et Al. ( 2004 ) used the finite component theoretical account of the human natess to foretell the inactive force per unit area distribution between human and siting surface by it detailed and realistic geometric description. Hix et Al. ( 2000 ) developed technology methods and expertness in the country of truck place patterning to capture the effects of place kineticss on drive quality. Figure 2.16 shows some CAE techniques that used to mensurate the place objectively.
PAM comfort simulation tool
AnyBody Modeling System
( GA, Fuzzy, SVM )
Figure 2.16 CAE techniques for place development
Physiological Measurements: Biological parametric quantities such as bosom rate, musculus, and piss can be used to mensurate the place comfort objectively. The biological parametric quantity is based on human organic structure physiological or orthopaedic phenomenon. For illustration, electromyography ( EMG ) signals is used to mensurate the myoelectrical activity of musculuss ( Inagaki et al. , 2000 ) , epinephrine in the piss can be used to mensurate the human emphasis degree ( Uenishi et al. , 2002 ) , electroencephalography ( EEG ) is used to mensurate the human encephalon activity ( Zhang et al. , 2006 ) , and O impregnation is used to look into the human uncomfortableness. Lim et Al. ( 2006 ) used a method of ECG measuring without direct contact with the tegument while topics sat on a chair have oning normal apparels. Figure 2.17 shows the assorted nonsubjective measuring methods for physiological analysis.
( Skin wettedness detector )
( ECG )
Electromyography ( EMG )
Skin wet trial ( Skincon-200/IBs )
Physiological clime simulator ( CYBOR )
A double manner dynamometer
Heat flux detector
Skin temperature detector
Oxygen impregnation measuring
( Somanetics Oximeter )
Electroencephalography ( EEG )
Figure 2.17 Various nonsubjective measuring methods for physiological analysis.
2.5.2 Relationship of subjective measurings to siting comfort and uncomfortableness
Due to the deficiency of proved analytical prosodies, vehicle makers have opted to trust on subjective ratings as the chief index of place comfort. The vehicle makers developed elaborative subjective rating protocols that involved extremely construction questionnaires ( Ahmadian et al. , 2002 ) . The questionnaires direct residents to delegate feelings of uncomfortableness to a specific part of place. The questionnaires, which typically contain numeral graduated tables ( e.g. 1 = really uncomfortable to 10 = really comfy ) , produce subjective evaluations that are translated into public presentation requirements/specifications ( Yagiz, 2004 ) . A decently designed questionnaire is paramount because it affords research workers an instrument from which to set up theories ( Brooks and Parsons, 1999 ) .
Local Discomfort Rating: Local uncomfortableness evaluation is used to mensurate the uncomfortableness of topics while sitting. Harmonizing to Kolich ( 2008 ) , many research workers have adopted Hertzberg ( 1972 ) definition because, in the current environment, it is more straightforward to quantify uncomfortableness than to mensurate comfort. The local uncomfortableness evaluation graduated table can be rate on a graduated table such as 1 to 10 or -10 to 10. Shen and Parsons ( 1997 ) used the class partitioning graduated table ( CP50 ) for evaluation seated force per unit area strength and perceived uncomfortableness. There are 16 surveies related with local uncomfortableness evaluation. Whereas there are six surveies related to local comfort evaluation.
In the survey by Mehta and Tewari ( 2000 ) , 10 point graduated table local uncomfortableness is used to mensurate the tractor place comfort. The work is to project the most appropriate method of appraisal and choice of tractor seats from technology and biomechanical position point. Eklund and Corlett ( 1987 ) used local uncomfortableness with ocular parallel graduated table to analyze the correlativity between bole and back uncomfortableness.
Local Comfort Rating: Kyung et Al. ( 2008 ) used several subjective evaluation strategies to look into the most effectual manner for usage in planing and measuring auto place, and to happen the relationship among these strategies. There are entire 27 Participants completed short-run drive Sessionss, in six combinations of seats ( from vehicles ranked high and low on overall comfort ) , vehicle category ( sedan and SUV ) , and driving locale ( lab based and field ) . Overall evaluations were obtained, every bit good as separate steps of comfort and uncomfortableness of the whole organic structure and local organic structure parts.
For the aircraft place, Parakkat et Al. ( 2006 ) investigated the long continuance effects of sitting in the expulsion place shock absorber. Subjective comfort study informations and cognitive public presentation informations is used in the probe. Zhang et Al. ( 2007 ) studied the thermic esthesiss, overall thermic acceptableness and thermic comfort on ocular parallel graduated tables. 7-point graduated table thermic comfort for each of the organic structure subdivisions is used in this studied.
Body Function: In the organic structure mapping method, the sensed uncomfortableness is referred to a portion of the organic structure. The topic is evaluation the organic structure countries sing uncomfortableness and to rate this uncomfortableness on a given graduated table. Kyung et Al. ( 2008 ) used a ocular organic structure mapping linear graduated table as shown in Figure 2.18 to obtain overall evaluations of comfort and uncomfortableness for the whole organic structure. For the work by Zenk et Al. ( 2007 ) , the uncomfortableness for each organic structure portion is rated on the uncomfortableness graduated table and apportion this appraisal to a specific section of the organic structure parts in touch with the place.
Figure 2.18 The organic structure function for comfort and uncomfortableness evaluation ( Kyung et al. , 2008 ) .
Seat Function: In the place function method, the place is divided into different subdivision to measure the seating comfort and uncomfortableness. Inagaki et Al. ( 2000 ) divided the place into 16 sections to measure place comfort based on 5-point graduated table. The `` fit '' feeling and `` soft '' feeling of the sitting place were converted to points of stimulation that the human organic structure received. Figure 2.19 shows the place mapping method by Inagaki et Al. ( 2000 ) .
Figure 2.19 Evaluation of place comfort based on place function ( Inagaki et al. , 2000 ) .
2.6 TOTAL DESIGN
Entire design is defined as the systematic activity necessary, from the designation of the market/user demand, to the merchandising of the successful merchandise to fulfill that demand - an activity that encompasses merchandise, procedure, people and organisation ( Pugh, 1990 ) . Entire design has been developed into an integrating model or methodological analysis that encapsulates all facets of the new merchandise development ( Ion, 1995 ) .
As mentioning to Figure 2.20, entire design is represented by an activity theoretical account that breaks the design procedure into six iterative phases- market reappraisals, merchandise design specification, construct design, item design, fabrication and merchandising. The attack accent the 'front terminal ' of the design procedure and includes many methods which are of direct relevancy to the apprehension of the market demands. The cardinal nucleus of activities as represented by the six stages is present in all design irrespective of subject. All design starts, or should get down with a demand that may be satisfied by bring forthing a merchandise that will suit into an bing market or make a market of its ain. This demand is expanded in the initial phases of the design procedure into a full merchandise design specification. This specification reflects the client demand and influences and restraints the remainder of activity. It is followed by conceptual procedure and item design. A merchandise that meets the merchandise design specification be developed and specified ( Ion, 1995 ) .
Figure 2.20 Entire design activity theoretical account ( Ion, 1995 ) .
To enable the design squad to run efficaciously and expeditiously, it is necessary to utilize a broad assortment of techniques and methods. These methods are straight related to the nucleus stages and efficaciously organize the design squad 's tool kit. Design methods may associate to analysis, synthesis, determination devising or some other facet of design and can either be independent of subject or engineering, such as originative methods, or subject specific, such as emphasis or thermodynamic analysis. The entire design attack is to the full compatible with the rules of concurrent technology ( Ion, 1995 ) .
2.7 ELECTROMYOGRAPHY AND STERNOCLEIDOMASTOID MUSCLE
An electromyography ( EMG ) signal is used to mensurate the myolectrical activity of musculuss. Muscles contractions send a mensurable electric potency that can be recorded by EMG ( Lee et al. , 1995 ) . Surface electromyography ( sEMG ) has been used in research and clinical applications for the non-invasive analysis of cervix musculuss to supply information about musculoskeletal conditions ( Falla et al. , 2002 ) . Sommerich et Al. ( 2000 ) discusses that at least a few of the musculuss of import for neck motion and stabilisation are accessible with surface electrodes. One of the musculuss is sternocleidomastoid ( SCM ) , where SCM is responsible for flexure, rotary motion and sidelong bending. Figure 2.21 shows the sternocleidomastoid musculus.
Figure 2.21 The sternocleidomastoid musculus ( Wikipedia, 2010 ) .
Costa et Al. ( 1990 ) described the authoritative text books of anatomy and kinesiology, see caput motions such as heterolateral rotary motion, homolateral disposition flexure and extension, of import maps of the sternocleidomastoid musculus. The map of the SCM musculus in caput motions of immature persons were studied electromyographically. From the consequences of the research, the caput motions performed by the SCM musculus were classified as heterolateral disposition, lengthiness, extension and flexure. Johnston et Al. ( 2008 ) studied the electromyography signals from the SCM musculus to find differences between computing machine workers with changing degrees of cervix hurting in footings of work stressors, employee strain, EMG amplitude and bosom rate response to assorted undertakings. Assorted surveies ( Ylinen et al. , 2003 ; Bexander et Al. 2005 ; Gabriel et al. , 2004 ; Moon et al. , 2003 ; Lin and Huang, 2008 ) showed that there is a relationship between electromyography ( EMG ) activity of sternocleido mastoideus ( SCM ) musculus and caput rotary motion.
The research characterized isometric rotary motion strength in the impersonal and in different pre-rotated places of the cervix. Twenty healthy work forces volunteered as topics. Maximal axial rotary motion strength of the cervix musculuss was measured in a impersonal place and bilaterally at 30A° and 60A° rotary motion utilizing the isometric cervix strength measuring system. Isometric maximal voluntary contractions of the cervix musculuss in flexure and extension were tested. The highest strength values were non reached in the impersonal place, but at the largest joint angles, while turning the caput in the opposite way from the pre-rotated place. Maximal strength increased with the increasing angle, and at the 60A° pre-rotation angle it was 44 % higher towards the right and 27 % higher towards the left compared to the values obtained in the impersonal place. The smallest strength values were besides produced at the largest pre-rotation angles, but in the same way. The consequences showed a clear relationship between the pre-rotated place of the cervix and maximum voluntary strength in rotary motion ( Ylinen et al. , 2003 ) .
Bexander et Al. ( 2005 ) conducted an experiment to look into the consequence of oculus place on neck musculus activity during cervical rotary motion. In the survey, the root-mean-square EMG amplitude was measured for 1 s during the period in which the place of the cervix and caput was held statically in each rotary motion angle ( 0, 15, 30, 45A° ) . The EMG amplitude of left SCM was increased when the cervix rotate from 0-45A° during left rotary motion and decreased during right rotary motion. The consequence of experiment indicated that activity of SCM was specific to the way of cervix rotary motion.
Moon et Al. ( 2003 ) developed a method to gauge face way angle utilizing both image observation and EMG signal from cervix musculuss. The EMG signal of the SCM musculus concerned in the caput motions is measured. The collarbone part is selected as the mention point for the EMG signal measuring because the collarbone is the nearest bone from cervix and it has no musculuss. During the experiment, when the caput is rotated to the right or left, the EMG signal is measured from the SCM at the opposite side. The consequences from the experiment showed that the alterations of EMG signals are little until 30A° , but additive belongingss are appeared in the scope [ 30A° , 90A° ] . There is a relationship between rotated caput angle and EMG signals.
Lin and Huang ( 2008 ) investigated the alterations of cervix musculus activities when utilizing different pillows in a clip series and different sort of pillow. There was a important lessening of SCM activity after 9th proceedingss up to 20th proceedingss when lying down from an unsloped place and non happened to upper cowl muscle musculus. The activities of SCM cervix musculuss decreased when altering craniocervical positions. The consequences confirm the ground of participants preferred proper cervix support. Tilley and Dreyfuss ( 2001 ) conducted human factors research impact everything in day-to-day life. In their measuring on caput rotary motion angle for adult male and adult female as mentioning to Figure 2.22, they defined that the caput confronting front or in 0A° is the most comfort caput place. From 0A° to 45A° is the easy caput rotary motion angle scope and 60A° is the maximal caput rotary motion angle.
0A° Most caput comfort
45A° Easy caput rotary motion
60A° Max caput rotary motion comfort
Figure 2.22 The caput rotary motion angle from top position ( adapted from Tilley and Dreyfuss, 2001 ) .
Literatures have provided theoretical theoretical account of siting comfort and uncomfortableness. There are different factors that affected the human comfort during travel, such as force per unit area, quiver, temperature and position. The rider has different degree of comfort and uncomfortableness during air travel. For the bing cervix support during travel, most of the cervix support used by rider is inactive back uping system where the rider needs to set the support when he/she feels uncomfortableness. There is no such adaptative cervix support for current aircraft place. Therefore, the end of this thesis work is to develop a cervix support system that can cut down the cervix musculus emphasis adaptively. There are different attacks that used to understand the comfort and uncomfortableness of sitting objectively every bit good as subjectively. Objective and subjective measuring methods can be combined for measuring both the comfort and uncomfortableness belongingss of seats. Literature reappraisal sing the cervix musculus showed that people need proper cervix support to cut down the cervix uncomfortableness. For this ground, sternocleidomastoid musculus that is responsible of caput rotary motion was selected for the proof of the developed smart cervix support system with surface electromyography methods.
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