The convenience of mobility options and multiple options available to people are a means to make their travelling faster, convenient and facilitative. The varied options within the vehicles also mean that each option serves to provide a few factors which allow the passenger better facilities and convenience than the others. It is not oblivious that in fact the price of each of this vehicle options vary sometimes considerably. This includes the factor of comfort and discomfort causes by car seats. The passenger may or may not face discomfort in the car seats based on a various qualitative factor including the time spent in travelling, the quality of the material used in making the car seats, noise, air pollution or even vibrations of the seats.
The following literature will explore various such experiments conducted to find factors involved in causing this discomfort. Based on it a conclusion will be formed and stated at the end of this literature.
From here on this literature review will seek to explore 4 basic reasons for causes of discomfort in car seats. This will be done based on various experiment conducted to fully explore each of the factors. These factors might not be the sole causes of discomfort, but these factors largely cover our research and present the information based on the same.
The author is Krunoslav Ormuž, Osman Mufti? and the article was published on 22nd October 2004. This report was written to establish a thesis so that the factors affecting discomfort in vehicle could be identified. The experiment is about Finding factors on which people base their opinion of comfort about. The study finds the factors influencing mainly riding comfort out the three classifications of comfort, namely the organizational, local and riding comfort.
Main results from this experiment includes the various simulation techniques and the understanding of various vibration profiles will allow automotive industries to compare and forma a basis for the vibration leading to discomfort caused by the simulation conditions involved in the study. Higher range of Oscillations (range between 1Hz-8-Hz) lead to reduced sensitivity of vibrations in the human body.
Of the major factors considered as the Ambient Factors responsible for causing discomfort, Vibrations is one of them. The human body is however made of different parts all of which react to the vibrations differently. The vibration in turn is also a result of a many factor which are a part of the vehicle and affect the overall passenger experience. These include the hardness of the main suspension; harder the suspension lesser the vibrations, the engine suspension, the profile of the tires; the tire discs are supposed to be wider and the vibrations reduce when the tires are larger, the car body and the seat itself. However, the greater level of seat comfort is based on the active and semi active main suspension.
The automotive industries manufacture vehicle vibration simulators which reproduce within the laboratories the profiles of vibrations already experienced n the roads. This helps them establish basis for the vibrations causing discomfort to the passengers. While each of the simulators are in operation and create vibration in the seat, the steering wheel, the vehicle floor, the brake and accelerator pedals, and the other contact points between the vehicle and the passenger are closely monitored.
We have therefore learnt that the resulting thesis which can be drawn from this experiment is that vibration which is considered to be a discomfort causing factor, is also a result of many factors which have been explored in this report and on the basis of this result, the automotive industries tend to form an analysis on reducing vibration and remove biases regarding the causes of vibration.
the Author for this article is Neil J. Mansfield, Jamie Mackrill, Andrew N. Rimell, and Simon J. MacMull. And it was published on 2nd January 2014.
This report was written because there have been various studies which have either focused on the static factors such as the seat shape and design, or the long-left000term discomfort from vibrations called fatigue properties and dynamics such as vibrations but never in the past before this study, all three have been combined together to form an analysis based on all three factors in the same study. This study seeks to explore to fill in this gap.
This experiment is about driving analysis of long term exposure to vibrations causing discomfort and lower back pain. This study seeks to explore the the results of exposing an individual’s whole body to vibrations over a long period of time by evaluation 3 different studies measuring discomfort caused by three seats of three different modes of transport. The study was carried out using two laboratory trials and one field trial. The participants were asked to rate their comfort or discomfort in each part of the body using Porter’s 7 points comfort rating scale as the participants were exposed to whole body vibrations. The results were then compared under each type of factors namely static, fatigue and dynamic properties. (Mansfield, 2014)
This experiment’s main outcomes revolve around the idea that undoubtedly duration of time an individual is made to sit and vibration are independent variables that lead to discomfort. However, it was also recorded that increasing vibrations accelerates the rate of discomfort across all the three trials that were conducted.
The three trials that were conducted in this study involved firstly the laboratory trial where the long-term discomfort caused in an automobile seat was discovered. This was a static properties test where the design and shape of the seat were the main factor at test. It was determined if just sitting for long time in the car seat causes any discomfort and at what point. A number of groups were subjected to discomfort for 80 minutes in total. Starting from no vibration at first and then rating their discomfort every 10 minutes, the subjects who were each exposed to identical conditions were asked to rank each time until at the end of the experiment when they were allowed to mount off the car which was on a vibration simulator before. Porter’s 7 Points comfort rating scale was used to rate the comfort level/discomfort and then a mean was calculated from all the groups showing the mean discomfort. It was measured that although sitting long hours in the car seat caused discomfort however, exposure to vibration accelerated the rate of discomfort.
In the second trial which was again a laboratory trial, but this was repeated with a rail seat. The measures taken in study 1 were repeated and the participants were made to sit for 50 mins exposed to vibrations and rated their discomfort. After 50 mons they were asked to sit in a stationary position without vibration and the discomfort was again measured using the same scale. The results achieved were directly comparable to that of study 1. The mean value for discomfort in this study was 3.5.
right7366000Study 3 was based on a Field Study of Long-Term Discomfort of Passengers in an Automobile. It was found that discomfort increased with time in both stationary positions and driving positions. It was found that though the discomfort increased based on the duration of time meaning the level of discomfort is positively linked to time duration and vibration both. But it was found that the driving position causes greater discomfort than the stationary one. 111823526352500
The thesis that can be drawn from the above conducted studies is that duration of time and the level of vibration are two independent variables affecting the level f discomfort. The discomfort will be affected in the presence of either of the variables but given that the participant is exposed to both, the participant will be facing discomfort at a faster rate and at shorter time intervals.
1.2 Driving Ergonomics
Movement analysis to indicate discomfort in vehicle seats
The first article in this regard is written by Neil Mansfield, George Sammonds, Nizar Darwazeh, Sameh Massoud, Alessandro Mocio, Taran Patel, Aamanh Sehdev. And published on 8th June 2018. It can be seen that the name of this particular article is Movement analysis to indicate discomfort in vehicle seats. When it comes to driving comfort, and maximizing the comfort that is generated with travelling, there is a need to ensure that the overall driving ergonomics are also considered well in this regard. Long distance travel is mostly associated with discomfort and fatigue. Therefore, in this regard, it is quite challenging to ensure that they are able to design a seat which is comfortable for the occupant over the given journey, even if it is longer in length.
Therefore, in phases of design, it is quite important to ensure that they are able to take these considerations into account, for purposes of research and development. In this particular paper, they consider a system that uses measurements of overall body movement in the given seat to provide an objective measure of perceptions of discomfort. In order to evaluate the overall validity of the scheme of affairs, it was quite important to use cameras and image processing in order to recognize when exactly would a participant make a movement in the seat in order to be able to make an objective measure of perceptions of discomfort. Therefore, this was done using a simulator, and ten participants who were asked to take part in order to evaluate the overall driving ergonomics.
Using these results, it could be shown that a simple algorithm can be used to develop an association between the movements that were made by the driver, and the overall subjective ratings of discomfort. Therefore, there are certain key takeaways that can be taken in this regard. They include the overall ability to ensure that the seats are designed in the manner to ensure that the experience is smooth and giving in this aspect.
This analysis, which has been presented in this can be seen in light of ensuring that vehicle agronomics are duly taken into consideration in order to ensure that the design, and otherwise, provide maximum support to the passengers. In this regard, there are some key learnings that should be considered, keeping in mind the overall movements that take place. Therefore, it can be seen that these aspects shape up the overall extent with which they are able to design seats, and shape up the comfort of the given cars.
Vehicle ergonomics: Driving Comfortably
https://www.iosh.co.uk/~/media/Documents/Networks/Branch/Edinburgh/Vehicle%20ergonomics%2011Oct12.pdf?la=enThis article is written by Margaret Hanson and published on 12 October 2011. There has been significant research done in areas of ensuring that the overall vehicle agronomics are taken into deep consideration in order to maximize the overall comfort that is duly derived from cars in the driving process. As a matter of fact, it can also be seen that there have been scientific researches that have been done in this area, essentially because of the fact that these researches have led to further insights for the car manufacturers about the overall ability to ensure that they are able to design as per general movements. The basic aim in this regard is to be able to create car seats which can provide excellent comfort, without compromising much on cost. (Kyung, 2009)
Therefore, in order to study this particular topic, Margaret Hanson. She was Principal Ergonomics Consultant. In the same manner, it can be seen she ventured to research on business aspects. 65% reported low back-pain, 43% neck discomfort and 40% reported to have shoulder pain amidst the review that was conducted across the business drivers. In the same manner, 1/3 of all the drivers in context reported that they experienced moderate or severe low back discomfort in a typical week. (Nussbaum, 2009)
In the same manner, it was further deduced that low-back related sickness absence is 6 times greater for those who drive more 4 hours a day. Additionally, drivers who spend >50% of their day driving were 3 times more likely to experience a slipped disc. The main causes of these issues were based on the fact that the posture was not right, which increased the overall pressure on discs. Therefore, the overall car design in this regard was quite important, as it helped to be able to maximize the overall transition process, and be able to get in and out of the car without much hassle.
This article is important as it highlights the overall importance of car design and manufacture in order to be able to ensure maximum safety and comfort. These areas are pertaining not just to the seat design itself, but also in the overall way the seat is placed, and the material that is used to manufacture the given seats.
1.3 Driving posture
The Effect of an Active Lumbar System on the Seating Comfort of Officers in Police Fleet Vehicles
This article is written by Cyril J. Donnelly, Jack P. Callaghan & Jennifer L. Durkin and published on 8th January 2015. Over the years, it can be seen that scientific research has been presented in order to evaluate the overall comfort that is present in the vehicles. For this purpose, it can be seen that there are numerous samples that can be chosen from, and these samples are essentially from those people who are likely to spend a higher amount in the vehicles altogether. As a matter of fact, policemen are likely to be more analytic about the overall comfort that is present in the car seats, which makes the overall discussion quite relevant in this regard. (Donnelly, C. J., Callaghan, J. P., & Durkin, J. L., 2009)
Scribed by Cyril J. Donnelly, Jack P. Callaghan & Jennifer L. Durkin, effect of the active lumbar seating comfort can actually be analyzed in line with the impact on policemen. In the same manner, it can be seen that the main purpose of this study were to determine which seat features/occupational demands contribute to the police officers discomfort and whether an automobile seat fitted with an active lumbar system (ALS) could reduce the overall driving discomfort. For this purpose, as many as fifty-eight officers were given questionnaires to assess driving discomfort. The main key achievements in this regard were high level of discomfort levels were essentially associated with computer use, duty belt, sidearm/radio, body armour and lumbar support interface. The main discomfort was discovered to be the most highest in the lumbar, sacrum, upper pelvis and mid-back regions. Therefore, it can be seen that there are mostly lumbar issues that relate to the overall discomfort that is caused in the car, to speak the least. (Donnelly, C. J., Callaghan, J. P., & Durkin, J. L., 2009)
As far as the driving posture is concerned, it can be seen that driving posture is basically a very crucial and an important determinant to the overall ability of being able to ensure that the comfort while travelling in the overall car is maximized. There are certain articles which have been presented in this regard. These articles present scientific evidence about the overall ability of the driving posture that impacts the scheme of affairs.
This analysis, despite the fact that is carried out on most policemen, can be seen in the light of overall application to the daily life scenarios. As a matter of fact, there is no doubt to the fact that policemen probably spend a lot of time in the vehicles. Therefore, in terms of longer drive times, it can be seen that posture support is essentially a very important predetermining factor in determining the overall comfort that one is able to have in this regard. The analysis showed the pressure points that existed, and how these pressure points were so important in shaping the overall experience. These points need to be duly identified by the seat manufacturers in order to be able to maximize the overall relevance of the comfort being induced in their seats, to say the least. (Donnelly, C. J., Callaghan, J. P., & Durkin, J. L., 2009)
Keegan, J. J. (1964). The Medical Problem of Lumbar Spine Flattening in Automobile Seat. SAE paper no. 83A.
This article is written by Matthew P. Reed, Lawrence W. Schneider, Bethany A. H. E and published on 31st march 1995. As far as this article is concerned, it can be seen that the overall medical problem of lumbar spine flattening in Automobile seat. As a matter of fact, it is an inherent assumption that an appropriately contoured lumbar support is widely regarded as an essential component of a comfortable auto seat. However, most laboratory experiments have been used to demonstrate that lumbar intervertebral disc pressure is quite lower when the spine is in an extended posture, to say the least. In light of the research that has been presented in this regard, it can be seen that researchers recommend longitudinally convex seatback contours that are designed to maintain or induce lordosis in the lumbar spine. (Keegan, J. J. ,1964)
In the present study that has been presented, it can be seen that laboratory experiments were subsequently conducted in order to investigate and study the overall effects of changes in seatback contour on the overall driver posture. The primary goal of the research is intended to refine and identify preferred driving postures for a range of seatback contours. Preferred postures were duly determined in order to prefer driving postures for a range of seatback contours. In the same manner, it can be seen that they worked towards identifying if the drivers were able to respond to longitudinally convex lumbar supports in auto seats by sitting with lumbar lordosis.
(Keegan, J. J. ,1964)
For this purpose, it can be seen that as many as 48 male and female subjects from four stature gender groups were operated in an interactive laboratory driving simulator for three one-hour sessions with the given lumbar support of a test seat adjusted to produce prominences of 0, 10, and 25 mrn. Before each session, they decided to record the standing posture of the subject was recorded. In the same manner, posture and subject back contour data were subsequently collected through a customized sonic digitizing system. In the same manner, it can be seen that changes in posture over the one-hour simulations were quite significant.
Therefore, it can be seen that there are numerous aspects that can be duly be considered in this regard, as it can be deduced from this particular scientific experiment that the overall driving posture is quite important, essentially because of the fact that back support really shapes the overall driving experience. With this objective in mind, it can be seen that driving with a back support is quite crucial, as it shapes ones posture, and makes it easier to adjust with longer drive times.
1.4 Pressure distribution and Hemodynamics
The Human Buttocks in Sitting: Pressures, Patterns, and Palliatives
https://www.researchgate.net/publication/235206648_The_Human_Buttocks_in_Sitting_Pressures_Patterns_and_Palliatives and https://deepblue.lib.umich.edu/bitstream/handle/2027.42/873/79692.0001.001.pdf;sequence=2 (page 32)
There have been numerous instances where it can be seen that there are issues pertaining to the overall car seat design, and the body mechanics. The modern designs that are being done are done so to ensure that they are able to inculcate the body shapes and sizes to optimize the overall scheme of affairs. Therefore, this article by Hertzberg, H was written with the same objective to ensure that they were able to cover most of these aspects and get a better blueprint for car designs.
Given the individual differences that exist in domains of overall postures, and body shapes, it can be seen that the overall relevancy of the buttock structure is also quite important. The shape of the buttock, and how it creates a pressure on rest of the body as a result of the seating arrangement is something that needs to be duly taken into account in order to properly understand the overall viability of the car designs. Therefore, after a brief description of relevant buttock structure, it can be seen that the author presented summary data based on the buttock size, specific tuberosity locations, and other different dimensions that were needed in order to create an improved seat design. This was done, as measured from a random sample of 35 young males. (Hertzberg, 1972)
Therefore, based on these research, it is important to ensure that the overall support in seats pertaining to buttock sizes is also taken in consideration. This is crucial for overall safety purposes. Given the fact that there is a new trend in this regard, it is quite crucial to be able to factor in the size of the seat altogether, and to design seats in order to be able to ensure that there is no unnecessary pressure on the pelvic bones, and the seat fits in properly in this regard.
Glassford, E.J. (1977) The relationship of hernodynamics to seating comfort. SAE paper no. 77024. (page 33)
https://deepblue.lib.umich.edu/bitstream/handle/2027.42/873/79692.0001.001.pdf;sequence=2This article is written by E.J Glassford and published in 1977. This article was meant to find out about how physiological changes relate to subjective judgements of discomfort in order to understand the factors of discomfort better. The two factors that were measured using an air displacement plethysmograph were namely the blood flow index and secondly the blood accumulation index. 30 items of semantic differential scales and body area discomfort ratings were used to gauge subjective judgement.
As a result of this it was found that blood accumulation has a positive co relation with deep, restful and secure sensation and secondly blood accumulation has a negative co relation with comfort and supporting back.
As a result, it can be found that sitting postures have a great impact on the feeling of comfort and discomfort. A relaxed sitting position can allow the feeling of comfort rather than discomfort. This also explains that sitting in a fixed position which is not very relaxing might also lead to some tissue damage and feeling of discomfort both.
Therefore, it can be seen in conclusion that there are numerous aspects which need to be duly taken into account on part of the car manufacturers in order to be able to maximize the overall state of affairs, and ensure maximum comfort for the passengers, to say the least.
Based on the analysis that has been presented above, it can be seen that there are numerous takeaways that can be gauged from this analysis. Firstly, despite the fact that there were features which can be directly associated with the comfort. As far as vibrations are concerned, the analysis and scientific research that is present in this regard shows that vibrations do impact the overall comfort that is present in the car. However, vibrations are usually inevitable and there needs to be a way to ensure that these vibrations are minimized. (Akkarakittichoke, N., & Janwantanakul, P, 2017). For vehicle occupants, two frequency ranges are considered: 0,5–80 Hz for health, comfort, and perception; and less than 1,0 Hz for motion sickness.
In the same manner, it can be seen that the most crucial aspect in this regard is perhaps that of ensuring that they are able to take into consideration the overall driving comfort ergonomics. The design, and the ability to ensure that they are able to design cars which can maximize the comfort for the drivers and the passengers. Therefore, car design can be seen in the light of lumbar support, the pressure points that exist, and how these pressure points can subsequently be targeted in this regard to minimize the overall pain. The best angle to support your back and give you the optimum comfort level is 15 degrees. There are multiple factors that can add to the general feeling of discomfort for people while they are travelling including a improper seat design which will not take into consideration the buttock sizes, the angle of the back support allowed by seats which will also impact the blood flow/circulation. Further as we analyzed in this literature that drivers who spend >50% of their day driving, were 3 times more prone to experience a slipped disc, therefore, it is important that car manufacturers pay more attention to car seats designs that will allow drivers a more comfortable drive and sitting posture. The quality and shape of the seat both play an important role in the comfort level of seats in automobiles.
Akkarakittichoke, N., & Janwantanakul, P. (2017). Seat Pressure Distribution Characteristics During 1 Hour Sitting in Office Workers With and Without Chronic Low Back Pain. Safety and Health at Work,8(2), 212-219. doi:10.1016/j.shaw.2016.10.005
Donnelly, C. J., Callaghan, J. P., & Durkin, J. L. (2009). The Effect of an Active Lumbar System on the Seating Comfort of Officers in Police Fleet Vehicles. International Journal of Occupational Safety and Ergonomics,15(3), 295-307. doi:10.1080/10803548.2009.11076809
Hertzberg, H. T. (1972). The Human Buttocks in Sitting: Pressures, Patterns, and Palliatives. SAE Technical Paper Series. doi:10.4271/720005
Keegan, J. J. (1964). The Medical Problem of Lumbar Spine Flattening in Automobile Seats. SAE Technical Paper Series. doi:10.4271/640788
Kelly, J. (n.d.). Vehicle Ergonomics. Retrieved from https://www.iosh.co.uk/~/media/Documents/Networks/Branch/Edinburgh/Vehicle ergonomics 11Oct12.pdf?la=enKyung, G., & Nussbaum, M. A. (2009). Specifying comfortable driving postures for ergonomic design and evaluation of the driver workspace using digital human models. Ergonomics,52(8), 939-953. doi:10.1080/00140130902763552
Mansfield, N. J., Mackrill, J., Rimell, A. N., & Macmull, S. J. (2014). Combined Effects of Long-Term Sitting and Whole-Body Vibration on Discomfort Onset for Vehicle Occupants. ISRN Automotive Engineering,2014, 1-8. doi:10.1155/2014/852607
Pollard, M. (1979). Vehicle Suspension Systems and Passenger Comfort. Design for Passenger Transport,65-75. doi:10.1016/b978-0-08-023735-0.50016-7
Woods, M. (1996). The Discomfort of Car-Seats. Books Ireland,(197), 242. doi:10.2307/20631598