Driving a better driving experience: a questionnaire survey of older compared with younger drivers.

A questionnaire survey of drivers (n = 903) was conducted covering musculoskeletal symptoms, the vehicle seat, access to specific vehicle features, ingress/egress, driving performance and driving behaviours. Significantly, more discomfort was reported by older drivers (aged 65+) in the hips/thighs/buttocks and knees. Older drivers reported more difficulty parallel parking (p ≤ 0.01), driving on a foggy day (p ≤ 0.01), and turning their head and body to reverse (p ≤ 0.001). They also reported that their reactions were slower than they used to be (p ≤ 0.01). Dissatisfaction was found by all drivers with adjusting the headrest (height and distance), seat belt height and opening/closing the boot. There is a growing population of older people globally, and the number of older drivers is showing a parallel increase. Clearly, efforts are needed to ensure car design of the future is more inclusive of older drivers. Practitioner Summary: This paper describes a questionnaire survey of drivers on their driving experience - the vehicle seat, access to specific vehicle features, ingress/egress, driving performance and driving behaviours. Comparisons are made by age and gender. Issues with driving and vehicle design particularly for older drivers in the UK are identified.

Contribution of individual components of a job cycle on overall severity of whole-body vibration exposure: a study in Indian mines.

Drivers of earth-moving machines are exposed to whole-body vibration (WBV). In mining operations there can be a combination of relatively high magnitudes of vibration and long exposure times. Effective risk mitigation requires understanding of the main aspects of a task that pose a hazard to health. There are very few published studies of WBV exposure from India. This paper reports on a study that considered the contribution of the component phases of dumper operations, on the overall vibration exposure of the drivers. It shows that vibration magnitudes are relatively high, and that haulage tasks are the main contributor to the exposure. It is recommended that driver speed, haul road surfaces and vehicle maintenance/selection are optimized to ensure minimization of vibration. If this is not sufficient, operation times might need to be reduced in order to ensure that the health guidance caution zone from Standard No. ISO 2631-1:1997 is not exceeded.

Effects of vertical and side-alternating vibration training on fall risk factors and bone turnover in older people at risk of falls.

BACKGROUND: whole-body vibration training may improve neuromuscular function, falls risk and bone density, but previous studies have had conflicting findings. OBJECTIVE: this study aimed to evaluate the influence of vertical vibration (VV) and side-alternating vibration (SV) on musculoskeletal health in older people at risk of falls. DESIGN: single-blind, randomised, controlled trial comparing vibration training to sham vibration (Sham) in addition to usual care. PARTICIPANTS: participants were 61 older people (37 women and 24 men), aged 80.2 + 6.5 years, referred to an outpatient falls prevention service. METHODS: participants were randomly assigned to VV, SV or Sham in addition to the usual falls prevention programme. Participants were requested to attend three vibration sessions per week for 12 weeks, with sessions increasing to six, 1 min bouts of vibration. Falls risk factors and neuromuscular tests were assessed, and blood samples collected for determination of bone turnover, at baseline and following the intervention. RESULTS: chair stand time, timed-up-and-go time, fear of falling, NEADL index and postural sway with eyes open improved in the Sham group. There were significantly greater gains in leg power in the VV than in the Sham group and in bone formation in SV and VV compared with the Sham group. Conversely, body sway improved less in the VV than in the Sham group. Changes in falls risk factors did not differ between the groups. CONCLUSIONS: whole-body vibration increased leg power and bone formation, but it did not provide any additional benefits to balance or fall risk factors beyond a falls prevention programme in older people at risk of falls.

Predicting the health risks related to whole-body vibration and shock: a comparison of alternative assessment methods for high-acceleration events in vehicles.

In this paper, alternative assessment methods for whole-body vibration and shocks are compared by means of 70 vibration samples measured from 13 work vehicles, deliberately selected to represent periods containing shocks. Five methodologies (ISO 2631-1:1997, BS 6841:1987, ISO 2631-5:2004, DIN SPEC 45697:2012 and one specified by Gunston [2011], 'G-method') were applied to the vibration samples. In order to compare different evaluation metrics, limiting exposures were determined by calculating times to reach the upper limit thresholds given in the methods. Over 10-fold shorter times to exposure thresholds were obtained for the tri-axial VDV (BS 6841) than for the dominant r.m.s. (ISO 2631-1) when exposures were of high magnitude or contained substantial shocks. Under these exposure conditions, the sixth power approaches (ISO 2631-5, DIN SPEC, G-method) are more stringent than a fourth power VDV method. The r.m.s. method may lead to misleading outcomes especially if a lengthy measurement includes a small number of severe impacts. In conclusion, methodologies produce different evaluations of the vibration severity depending on the exposure characteristics, and the correct method must be selected. PRACTITIONER SUMMARY: Health risks related to whole-body vibration and high acceleration events may be predicted by means of several different methods. This study compares five such methods giving emphasis on their applicability in the presence of shocks. The results showed significant discrepancies between the risk assessments, especially for the most extreme exposures.

A survey of expert opinion on the effects of occupational exposures to trunk rotation and whole-body vibration.

We present a review of current expert opinion on the effects of combined exposures to trunk rotation and whole-body vibration (WBV), commonly experienced by operators of agricultural machinery. We evaluate the level of agreement between academic experts in the field of ergonomics, human response to WBV and agricultural operators, on the effects of exposure to WBV and trunk rotation. A total of 83 individuals responded to the paper-based questionnaire, which included questions on risk levels from individual and combined exposures, discomfort development, exposure duration limits and tasks within agriculture. The results showed that all groups considered exposure to WBV and trunk rotation as risk factors for the development of back pain. The experts were not in consensus regarding acceptable exposure durations, areas of discomfort experienced or recommendations for cab developments.

Modeling passenger comfort in turboprop aircraft using objective measures.

BACKGROUND: A quantitative comfort model will aid in evaluating comfort levels of various target groups before the actual flight of an airplane. However, constructing the model is always a challenge due to the complexity of the phenomenon. OBJECTIVES: In this paper, we present quantitative comfort models to predict the (dis)comfort of passengers flying with turboprops based on objective measures. METHODS: Ninety-seven participants took part in two experiments conducted during real flights, during which forty of them had environmental and personal factors recorded using (self-developed) measurement tools. The collected data were analyzed to model the relations between objective measures and subjective feelings. RESULTS: Two preliminary models based on gradient boosting regression were developed. The models were able to predict the changes in comfort and discomfort of individual passengers with an accuracy of 0.12±0.01 and 0.21±0.01 regarding normalized comfort and discomfort scores, respectively. Additionally, contributions of different factors were highlighted. CONCLUSION: The outcomes of the models show that we took a step forward in modeling the human comfort experience using objective measurements. Anthropometry (including age), seat positions, time duration, and row (noise) emerged as leading factors influencing the feeling of (dis)comfort in turboprop planes.

Subjective ratings of whole-body vibration for single- and multi-axis motion.

Real-world whole-body vibration exposures comprise motion in fore-aft, lateral, and vertical directions simultaneously. There can also be components of roll, pitch, and yaw. If evaluating vibration with respect to human response, most investigators will use methods defined in ISO 2631-1. This uses frequency weightings that were originally derived from laboratory studies of the subjective responses to vibration in one direction at a time. This paper describes experiments that were carried out using a 6 degree-of-freedom vibration simulator to validate the applicability of ISO 2631-1 in multi-axis environments. Fifteen subjects were exposed to 87 stimuli comprising single-axis, dual-axis, and tri-axial random vibration, to which they were required to produce subjective ratings. It is shown that in this study the root-sum-of-squares method of summation of subjective ratings in individual axes was an adequate technique for prediction of subjective rating of multi-axis vibration. Better agreement between objective and subjective measures of vibration was obtained for unweighted vibration than for frequency weighted signals. The best agreement for this study was achieved when axis multiplying factors were set at 2.2 and 2.4 for x- and y-axis vibration, respectively. Different values could be appropriate for other postures, seats, and vibration conditions and should be determined in future studies.

Whole body vibration in helicopters: risk assessment in relation to low back pain.

INTRODUCTION: Helicopter pilots are exposed to whole body vibration (WBV) in their working environment. WBV has been associated with low back pain (LBP) and helicopter pilots have a high prevalence for LBP compared with other professions. The aim of this study was to develop a test protocol for measuring helicopters with ISO 2631-1 and to perform a whole body vibration risk assessment based on the European Vibration Directive in a number of commonly used military and civilian helicopters. Both absolute values and individual difference in current helicopter types are of interest in order to evaluate the possible role of vibration in LBP in helicopter pilots. METHODS: In operationally relevant maneuvers, six helicopters were tested. In order to standardize measurements, each continuous flight was split into 15 separate maneuvers. A model of a working day exposure pattern was used to calculate A(8) vibration magnitudes for each helicopter. RESULTS: The vibration A(8) exposure estimates ranged from 0.32-0.51 m x s(-2) during an 8-h working day A(8). This compares with EU and ISO lower bounds risk criteria of 0.5 and 0.43 m x s(-2) A(8), respectively. DISCUSSION: Despite the vibration levels being relatively low, helicopter pilots report a high incidence of LBP. It is possible that helicopter pilot postures increase the risk of LBP when combined with WBV. The test protocol used in this study could be generally applied for other rotary winged aircraft testing to allow for comparison of WBV results. Data from different flight phases could be used to model different exposure profiles.

Driver seat comfort for level 3-4 autonomous vehicles.

BACKGROUND: Autonomous vehicles can be classified on a scale of automation from 0 to 5, where level 0 corresponds to vehicles that have no automation to level 5 where the vehicle is fully autonomous and it is not possible for the human occupant to take control. At level 2, the driver needs to retain attention as they are in control of at least some systems. Level 3-4 vehicles are capable of full control but the human occupant might be required to, or desire to, intervene in some circumstances. This means that there could be extended periods of time where the driver is relaxed, but other periods of time when they need to drive. OBJECTIVE: The seat must therefore be designed to be comfortable in at least two different types of use case. METHODS: This driving simulator study compares the comfort experienced in a seat from a production hybrid vehicle whilst being used in a manual driving mode and in autonomous mode for a range of postures. RESULTS: It highlights how discomfort is worse for cases where the posture is non-optimal for the task. It also investigates the design of head and neckrests to mitigate neck discomfort, and shows that a well-designed neckrest is beneficial for drivers in autonomous mode.

Introduction to the special issue on comfort: A review of 26 papers from the International Comfort Congress 2019.

Various aspects related to comfort are described in this special issue. Some papers are focused on the environment, like smell, temperature, light, acoustics, space and some on an artefact touching the human, like the floor angle, the seat, a bed and light. However, in this special issue also topics like modelling and behavior get more attention.

Large Deformation Finite Element Analyses for 3D X-ray CT Scanned Microscopic Structures of Polyurethane Foams.

Polyurethane foams have unique properties that make them suitable for a wide range of applications, including cushioning and seat pads. The foam mechanical properties largely depend on both the parent material and foam cell microstructure. Uniaxial loading experiments, X-ray tomography and finite element analysis can be used to investigate the relationship between the macroscopic mechanical properties and microscopic foam structure. Polyurethane foam specimens were scanned using X-ray computed tomography. The scanned geometries were converted to three-dimensional (3D) CAD models using open source, and commercially available CAD software tools. The models were meshed and used to simulate the compression tests using the implicit finite element method. The calculated uniaxial compression tests were in good agreement with experimental results for strains up to 30%. The presented method would be effective in investigating the effect of polymer foam geometrical features in macroscopic mechanical properties, and guide manufacturing methods for specific applications.

PCQ: Preferred Comfort Questionnaires for product design.

BACKGROUND: Selecting the most suitable questionnaire(s) in comfort research for product design is always a challenge, even for experienced researchers. OBJECTIVE: The objective of this research is to create a list of Preferred Comfort Questionnaires (PCQ) for product design to help researchers in the selection of questionnaires for comfort research. METHODS: Fifteen questionnaires that are often used in comfort research for product design were selected as candidate questionnaires. During the Second International Comfort Congress (ICC 2019), 55 researchers and practitioners working in the field of comfort joined together in a workshop to rate these questionnaires individually as well as rank them in groups based on their experience. The criteria of rating and ranking included easiness to answer, easiness for data interpretation, time needed to complete, the need for prior training, as well as mapping the applicable design phases and field of application. RESULTS: The elicited responses related to each questionnaire were analyzed. For comfort research in five proposed application fields and four design phases, the preferred questionnaires were highlighted and categorized into four categories: preferred questionnaire, suitable for less prior training, suitable for fast completion and generally applicable, which led to a list of PCQ for product design. CONCLUSION: We expect that the PCQ list can be used as a useful instrument to help researchers in selecting questionnaires for comfort research in product design.

A biomechanical analysis of common lunge tasks in badminton.

The lunge is regularly used in badminton and is recognized for the high physical demands it places on the lower limbs. Despite its common occurrence, little information is available on the biomechanics of lunging in the singles game. A video-based pilot study confirmed the relatively high frequency of lunging, approximately 15% of all movements, in competitive singles games. The biomechanics and performance characteristics of three badminton-specific lunge tasks (kick, step-in, and hop lunge) were investigated in the laboratory with nine experienced male badminton players. Ground reaction forces and kinematic data were collected and lower limb joint kinetics calculated using an inverse dynamics approach. The step-in lunge was characterized by significantly lower mean horizontal reaction force at drive-off and lower mean peak hip joint power than the kick lunge. The hop lunge resulted in significantly larger mean reaction forces during loading and drive-off phases, as well as significantly larger mean peak ankle joint moments and knee and ankle joint powers than the kick or step-in lunges. These findings indicate that, within the setting of this investigation, the step-in lunge may be beneficial for reducing the muscular demands of lunge recovery and that the hop lunge allows for higher positive power output, thereby presenting an efficient lunging method.

Effects of horizontal whole-body vibration and standing posture on activity interference.

Standing people are exposed to whole-body vibration in many environments. This paper investigates the effects of horizontal whole-body vibration and standing posture on task performance. Sixteen participants were exposed to random vibration (up to 4 Hz) whilst performing a timed pegboard task in two standing postures. Objective and subjective indicators of performance were used. Time taken to complete the task increased progressively with increases in vibration magnitude. The fore-and-aft posture generally showed greater performance decrements and postural interruptions (>1.0 ms(-2) root mean square) than the lateral. For both postures, performance was better during y-axis vibration than during x-axis vibration. Subjective ratings showed similar trends to time data. Impairments due to dual axis exposure were well predicted using root sum of squares calculations based on single axis components. These results indicate that best performance for those standing in moving environments will be achieved if individuals adopt a lateral posture with the most severe vibration in the y-axis. STATEMENT OF RELEVANCE: People have a need to work during transportation, either working for the transport provider or as a passenger. All modes of transport result in travellers being exposed to horizontal motion. This study demonstrates that task disturbance is affected by the orientation of the standing person to the vibration and, therefore, vehicle layouts can be optimised.

Physiological correlates of cognitive load in laparoscopic surgery.

Laparoscopic surgery can be exhausting and frustrating, and the cognitive load experienced by surgeons may have a major impact on patient safety as well as healthcare economics. As cognitive load decreases with increasing proficiency, its robust assessment through physiological data can help to develop more effective training and certification procedures in this area. We measured data from 31 novices during laparoscopic exercises to extract features based on cardiac and ocular variables. These were compared with traditional behavioural and subjective measures in a dual-task setting. We found significant correlations between the features and the traditional measures. The subjective task difficulty, reaction time, and completion time were well predicted by the physiology features. Reaction times to randomly timed auditory stimuli were correlated with the mean of the heart rate ([Formula: see text]) and heart rate variability ([Formula: see text]). Completion times were correlated with the physiologically predicted values with a correlation coefficient of 0.84. We found that the multi-modal set of physiology features was a better predictor than any individual feature and artificial neural networks performed better than linear regression. The physiological correlates studied in this paper, translated into technological products, could help develop standardised and more easily regulated frameworks for training and certification.

Integrating and applying models of comfort.

This paper gives an overview of the relevance of the comfort concept, its definitions, boundary conditions, and stakeholders. Current comfort theories are presented and reflected on, both in their applicability and testing methodology. Questionnaires commonly used to study comfort and discomfort are also reviewed. An example of a comfort lab is introduced in its functionality and tools, which can be useful as a benchmark for others studying comfort.

Bilateral ground reaction forces and joint moments for lateral sidestepping and crossover stepping tasks.

Racquet sports have high levels of joint injuries suggesting the joint loads during play may be excessive. Sports such as badminton employ lateral sidestepping (SS) and crossover stepping (XS) movements which so far have not been described in terms of biomechanics. This study examined bilateral ground reaction forces and three dimensional joint kinetics for both these gaits in order to determine the demands of the movements on the leading and trailing limb and predict the contribution of these movements to the occurrence of overuse injury of the lower limbs. A force platform and motion-analysis system were used to record ground reaction forces and track marker trajectories of 9 experienced male badminton players performing lateral SS, XS and forward running tasks at a controlled speed of 3 m·s(-1) using their normal technique. Ground reaction force and kinetic data for the hip, knee and ankle were analyzed, averaged across the group and the biomechanical variables compared. In all cases the ground reaction forces and joint moments were less than those experienced during moderate running suggesting that in normal play SS and XS gaits do not lead to high forces that could contribute to increased injury risk. Ground reaction forces during SS and XS do not appear to contribute to the development of overuse injury. The distinct roles of the leading and trailing limb, acting as a generator of vertical force and shock absorber respectively, during the SS and XS may however contribute to the development of muscular imbalances which may ultimately contribute to the development of overuse injury. However it is still possible that faulty use of these gaits might lead to high loads and this should be the subject of future work. Key pointsGround reaction forces and joint moments during lateral stepping are smaller in magnitude than those experienced during moderate running.Force exposure in SS and XS gaits in normal play does not appear to contribute to the development of overuse injuryThe leading and trailing limbs perform distinct roles, acting as a generator of vertical force and shock absorber respectively.This distinct contribution may contribute to the development of muscular imbalances which may ultimately contribute to the development of overuse injury.

Engineering movement into automotive seating: Does the driver feel more comfortable and refreshed?

The concept of introducing movement in automotive seating was investigated. Three seat conditions, a control (no movement) and two movement conditions (fore-aft and cushion-backrest) were compared. Movement was introduced at a fixed speed, slow, smooth and within a small range. Ten participants took part in a 60 min simulated drive for each condition - single blind, repeated measures, and balanced order. Discomfort ratings were collected for six body areas and overall discomfort, together with a wellbeing questionnaire. Driver posture and Seat Fidgets and Movements (SFMs) were captured. There was a trend for lower ratings of discomfort, overall and in the neck, shoulders, lower back, buttocks, and ankles with both seat movement conditions. Wellbeing ratings were also better with movement. Significant differences were found at minute 60 for buttock discomfort - less discomfort with seat movement. Overall discomfort and SFMs frequency increased with time driving. Generally, passive seat movement was well received.