Combined Effects of Long-Term Sitting and Whole-Body Vibration on Discomfort Onset for Vehicle Occupants

Occupants of automobiles experience discomfort after long drives, irrespective of how well designed a seat might be. Previous studies of discomfort during driving have focused either on the seat shape and materials (“static” properties), long-term discomfort (“fatigue” properties), or dynamics (“vibration” properties). These factors have previously not been considered together. This paper reports three studies with objectives to define and test a model for describing long-term discomfort from vibration. Study 1 was an independent measures laboratory trial using an automobile seat, which lasted 80 minutes; Study 2 was a repeated measures laboratory trial using a rail passenger seat, which lasted 60 minutes; Study 3 was a repeated measures field trial in a people carrier automobile, which involved 70 minutes of travelling. The findings showed that discomfort accrues with time but that more discomfort is experienced when subjects are also exposed to whole-body vibration. Exposure to whole-body vibration accelerates development of discomfort. The relationship between the reported discomfort, the vibration magnitude, and the exposure time can be described using a multifactorial linear model. It is concluded that ignoring parts of the multi-factorial model (i.e., static, dynamic, or temporal factors) will compromise understanding of discomfort in context

An approach to vehicle design: in-depth audit to understand the needs of older drivers

The population of older people continues to increase around the world, and this trend is expected to continue; the population of older drivers is increasing accordingly. January 2012 figures from the DVLA in the UK stated that there were more than 15 million drivers aged over 60; more than 1 million drivers were aged over 80. There is a need for specific research tools to understand and capture how all users interact with features in the vehicle cabin e.g. controls and tasks, including the specific needs of the increasingly older driving population. This paper describes an in-depth audit that was conducted to understand how design of the vehicle cabin impacts on comfort, posture, usability, health and wellbeing in older drivers. The sample involved 47 drivers (38% female, 62% male). The age distribution was: 50–64 (n = 12), 65–79 (n = 20), and those 80 and over (n = 15). The methodology included tools to capture user experience in the vehicle cabin and functional performance tests relevant to specific driving tasks. It is shown that drivers' physical capabilities reduce with age and that there are associated difficulties in setting up an optimal driving position such that some controls cannot be operated as intended, and many adapt their driving cabins. The cabin set-up process consistently began with setting up the seat and finished with operation of the seat belt

Design of digital filters for frequency weightings (A and C) required for risk assessments of workers exposed to noise

Many workers are exposed to noise in their industrial environment. Excessive noise exposure can cause health problems and therefore it is important that the worker’s noise exposure is assessed. This may require measurement by an equipment manufacturer or the employer. Human exposure to noise may be measured using microphones; however, weighting filters are required to correlate the physical noise sound pressure level measurements to the human’s response to an auditory stimulus. IEC 61672-1 and ANSI S1.43 describe suitable weighting filters, but do not explain how to implement them for digitally recorded sound pressure level data. By using the bilinear transform, it is possible to transform the analogue equations given in the standards into digital filters. This paper describes the implementation of the weighting filters as digital IIR (Infinite Impulse Response) filters and provides all the necessary formulae to directly calculate the filter coefficients for any sampling frequency. Thus, the filters in the standards can be implemented in any numerical processing software (such as a spreadsheet or programming language running on a PC, mobile device or embedded system)

Situation Awareness: its proficiency amongst older and younger drivers, and its usefulness for perceiving hazards.

This paper was accepted for publication in the journal Transportation Research Part F: Psychology and Behaviour and the definitive published version is available at http://dx.doi.org/10.1016/j.trf.2016.04.011The two studies reported here sought to measure and compare the Situation Awareness (SA) of younger and older driver groups whilst driving (Study 1), and watching video footage of actual car journeys (Study 2). In both studies this was achieved by recording a participant’s commentary on what s/he felt was of relevance to the driving task. The narratives produced were analysed by computer software that could abstract main concepts and calculate scores indicative of Situation Awareness. In Study 2, these scores were related to others for hazard perception proficiency (also derived from participant commentaries). It was found that the older drivers matched and often exceeded the younger drivers when their SA scores were compared individually, but not when assessed as a group. However, the younger drivers out-performed their older counterparts in hazard perception ability, and this was shown to be related to their Situation Awareness score. When the results from participants who undertook both studies were compared, it was found that Situation Awareness performance was significantly higher when commenting on video footage (Study 2) than whilst actually driving (Study 1)

Whole-body vibration experienced by pilots, passengers and crew in fixed-wing aircraft: a state-of-the-science review

Before the coronavirus pandemic, there were 4.5 billion passenger movements by aircraft annually; this is expected to recover after the pandemic. Despite the large numbers of flights per year, there are few reports of whole-body vibration in fixed-wing aircraft. This paper reports a review of literature intended to collate reported data related to exposure to whole-body vibration. Following a filtering process to select relevant articles, a literature search elicited 26 papers reporting measurements of vibration. These included measurements made in the cockpit and cabin, and for pilots, crew and passengers. Aircraft included military, commercial and passenger aircraft, turbo-props, jets and piston prop aircraft. There was a lack of consistency on measurement method and analysis, and few met the full requirements of ISO 2631-1. However, measurements showed significant components of vibration at frequencies largely attenuated by the ISO frequency weighting filters, but have been shown to be important in terms of human vibration perception. Propeller aircraft showed strong tonal components in vibration frequency spectra. There was also a significant effect of the flight phase in the vibration exposure. It is recommended that the body of literature related to human response to whole-body vibration on aircraft is augmented with further studies in order to understand in-flight experiences and to optimize human health, wellbeing, comfort and performance

Designing movement into automotive seating - does it improve comfort?

Comfort is important for a good driving experience and automotive seat technology is an important enabler of this. Movement through frequent changes in posture is beneficial for reducing fixed postures. This paper reports on a laboratory study to investigate a novel automotive seat movement concept aiming to delay the onset of driving-related musculoskeletal fatigue and improve feelings of comfort and wellbeing, making the driver feel refreshed and ultimately improving driver performance. The research involved comparison of three seat conditions while driving - no seat movement, fore-aft movement, cushion and backrest angle movement. The movement was designed to be at a fixed speed, slow, smooth and only slightly perceptible while driving. A sample of 10 participants was recruited to take part in a 60 minute drive for each condition-single blind, repeated measures, balanced order and sessions at a similar time of day. Discomfort and wellbeing questionnaires, driver Seat Fidgets and Movements (SFMs), posture capture and a de-brief were used as data collection methods. Results indicate that the two seat movement concepts were positively received. Statistically significant differences were found at minute 60 for buttock area discomfort, with less reported discomfort for the two movement conditions. As expected, overall discomfort ratings and SFMs frequency increased with time spent driving for all trials. Posture scores verified that driver posture was within comfortable ranges and as expected fairly static while driving

Movement analysis to indicate discomfort in vehicle seats

Long distance travel is associated with discomfort and fatigue. It is a significant challenge to design a seat that remains comfortable for the occupant over the several hours required for many long-distance journeys. When designing seats, an indication of the perception of comfort/discomfort can be useful either for research and development purposes or potentially for automated systems to take actions that might mitigate discomfort. This paper considered a system that uses measurements of body movement in a seat to provide an objective measure of perceptions of discomfort. The system uses cameras and image processing to recognize when a seat occupant makes a movement in the seat which could be associated with relief of discomfort. The system was validated using a laboratory driving simulator. 10 participants volunteered to complete a study in which they drove for 90 minutes and gave subjective ratings of discomfort every 10 minutes, whilst also being observed using the camera system. It was shown that using a simple algorithm an association could be made between the movements of the driver and subjective ratings of discomfort. However, there remain challenges to improve reliability, optimize movement detection thresholds, and to make it more robust to naturalistic driving scenarios

Apparent mass of small children: Experimental measurements

A test facility and protocol were developed for measuring the seated, vertical, whole-body vibration response of small children of less than 18 kg in mass over the frequency range from 1 to 45 Hz. The facility and protocol adhered to the human vibration testing guidelines of BS7085 and to current codes of ethics for research involving children. Additional procedures were also developed which are not currently defined in the guidelines, including the integral involvement of the parents and steps taken to maximize child happiness. Eight children were tested at amplitudes of 0.8 and 1.2 m/s2 using band-limited, Gaussian, white noise acceleration signals defined over the frequency interval from 1 to 50 Hz. Driving point apparent mass modulus and phase curves were determined for all eight children at both test amplitudes. All results presented a single, principal, anti-resonance, and were similar to data reported for primates and for adult humans seated in an automotive posture which provided backrest support. The mean frequency of the apparent mass peak was 6.25 Hz for the small children, as compared to values between 6.5 - 8.5 Hz for small primates and values between 6.5 - 8.6 Hz for adults seated with backrest support. The peak value of the mean, normalized, apparent mass was 1.54 for the children, which compares to values from 1.19 to 1.45 reported in the literature for small primates and 1.28 for adults seated with backrest support. ISO standard 5982, which specifies a mean, normalized, apparent mass modulus peak of 1.50 at a frequency of 4.0 Hz for adults seated without backrest support, provides significant differences

Fit to Race: Identifying the balance, type and sources of knowledge in fitness for Motorsport

In Motorsport, due perhaps to a lack of empirical evidence, it is not always clear what fitness training is required and what roles specific fitness components play, particularly outside the elite levels. Consequently, drivers and their trainers are often left to their own devices, placing reliance on anecdotal information. Accordingly, using a large sample of racing drivers, coaches and fitness trainers, the aim of this investigation was to identify the perceived importance and contribution of fitness components, the sources of information used to reach these conclusions and levels of confidence in the views reported. Survey data from 166 drivers (151 males, 15 females) showed that, in general, cardiovascular fitness, upper body strength, coordination and reactions were perceived as being the most important. Data on sources of information used supported the conjecture that training can often be based on “word of mouth”. Despite a fairly high level of confidence in the views expressed, there is clearly a significant opportunity for practitioners working within Motorsport to provide clearer, proven information so that drivers can feel confident that they are training optimally