Design and analysis of experiments aimed at improving the aircraft seat comfort for young and elderly passengers

Population ageing is becoming a global phenomenon. According to the United Nations report World Population Ageing, "the number of older people aged 60 or over was about 202 million in 1950, accelerated to 841 million in 2013, and will triple by 2050". The contextual implementation of active and healthy ageing policies, modifying the expectation, quality and lifestyle of the elderly, is offering opportunities and challenges on various aspects of daily life and health management: among the various positive aspects, this has determined an increase in mobility for recreational purposes and therefore an increasing complexity of the needs connected to it. These changing needs must be considered in the design of transport environments to ensure dignity and autonomy for passengers, in accordance with the policy of non-discrimination promoted by European regulations for users with reduced mobility (EC n.1107/2006). In 2017, following a positive trend begun in 2010, passengers who used air transport for their journeys to or from European Union countries exceeded the record figure of one billion for the first time. In 2018, according to Eurostat data, air traffic increased by a further 6% at European level, involving 1 billion 106 million passengers. In this European scenario, Italy is the fifth country in the EU ranking for the number of transported passengers, preceded in order by the United Kingdom, Germany, Spain and France, and is even in second place, preceded only by Spain, if referring to the transport of passengers on the national territory. In 2019, passengers transited through the 39 Italian airports monitored by Assaeroporti amounted to 193 million, i.e. 7.4 million more than the previous year equal to +4%, in line with the positive trend of previous years; among them, 19% on average were between 55 and 64 years old and 12% over 65 (Istat, May 2020). Together with the diversity of passenger population, it should be emphasized the change of their needs, helped by rapid technological development that allows passengers to carry out various activities from the comfort of their seats. Therefore, the heterogeneity of new transport needs makes it necessary to adopt an inclusive design approach, aimed at designing and implementing products that are accessible and usable by the largest number of potential users. The proposed research aims to support the ergonomic design of aircraft interiors in order to improve the quality of the mobility experience of both elderly passengers and passengers with reduced mobility. Specifically, the research started from the generation phase of their concept and went through the development of experimental protocols and methods for the evaluation of different design solutions and the continuous monitoring of postural comfort through temporal analysis of data collected by pressure and movement sensors. The research activity focused on the aspects of passive mobility, that is the context in which the air passenger operates (although the same can be extended to other contexts different from air transport, such as rail, sea or road transport): 1. identification of strategies and methods for assessing the accessibility and passenger comfort; 2. characterization of critical postural parameters to maximize passenger comfort; 3. elaboration of experimental protocols aimed at validating the feasibility of the proposed design solutions through experimental campaigns in real life. The activities related to the first point were carried out through an extensive analysis of the specialized literature concerning the analysis of (dis-)comfort both in aircraft environment and transport in general. The investigation then focused on methods for assessing the accessibility and (dis-)comfort of the passenger seat. Literature studies have focused most of the research activity on the evaluation and analysis of the experiences of young and healthy passengers who are able to move independently. Each study adopted different strategies preventing both comparison and generalization of results. Indeed, recent literature reviews have highlighted the need to develop methodologies for collecting and analyzing comfort data producing statistically significant evidence to provide diagnostic information to all stakeholders The activities inherent to the second point concerned the formulation of an evaluation strategy suitable to identify the needs of passengers, both young and old, and the critical features of the seat on which to intervene to maximize the comfort experience with respect to the functional characteristics of interest. These strategies were implemented during several experimental campaigns which, as described in the third point, involved the establishment of specific experimental protocols that allowed for replicability of the experimental tests and reliability of the results. In order to carry out the outlined activities, it was necessary to make use of different skills and tools. First of all, the experimental tests were designed with respect to appropriate methodologies for planning experiments (i.e. Design of Experiments, DOE) in order to minimize the number of tests and the impact of the main noise factors such as anthropometric characteristics of potential users, time and duration of the test. Two types of data were collected: subjective and objective measures. The collected subjective measures involved directly the selected sample who carried out an assessment of personally perceived (dis-)comfort, usability and accessibility (ease of ingress/egress) with respect to the conditions tested each time. The selected sample of participants was always sufficiently representative of the population of interest and was trained in advance to perform the test. To detect subjective measures, survey instruments such as questionnaires or checklists existing in the literature or specially elaborated and previously validated were used. The objective measures (i.e. pressure at the seat-occupant interface) were obtained using different instruments: mats equipped with sensors for both seat and backrest were used for the detection of pressures at the seat-occupant interface

A Modeling Study on Child Occupant Safety With Unconventional Seating Configurations

DTNH2215D00017/693JJ920F000158This study uses computer models to study how unconventional seating positions and orientations such as those conceptualized to be offered in vehicles with Automated Driving Systems may affect occupant response metrics of children restrained by child restraint systems (CRS) equipped with internal harnesses (CRS harness-restrained) or the vehicle lap-shoulder belt, with and without belt-positioning boosters. A total of 550 simulations were conducted with the CRABI 12MO in rear-facing CRS, the H33YO in both rear-facing and forward-facing CRS, the H36YO in a backless booster, and the H310YO with and without a booster across a range of conventional and unconventional seating locations and orientations under five impact directions and various CRS installation methods. This is the first study using different child ATDs and CRSs to investigate child occupant responses in a wide range of impact directions and seating orientations

Pediatric wheelchair and headrest design guidelines and the effect of headrests on relative injury risk under rear impact conditions

The role that wheelchairs and wheelchair mounted headrests play in rear impact occupant protection for children who remain seated in wheelchairs while traveling in motor vehicles was investigated using sled testing and computer simulation. Study goals were to establish pediatric wheelchair and headrest design guidelines and to determine the effect of headrests on relative injury risk outcome measures under rear impact conditions. Two series of sled tests (16 mph, 11g) were conducted using a Hybrid III 6-year old anthropomorphic test device (ATD) seated in identically configured manual pediatric wheelchairs, with and without headrests. Wheelchairs remained intact and the ATD remained upright. Rear impact front wheelchair securement points were subjected to loads similar to previously described (Ha, DongRan, 2004) rear securement points in frontal impact, although Ha used the more severe 30mph, 20g frontal impact WC19 - Wheelchairs Used as Seats in Motor Vehicles (ANSI/RESNA, 2000) crash pulse. Sled test ATD data analysis indicated that wheelchair headrest use had a potentially protective effect based on pediatric head and neck injury risk outcomes. Sled test data established response corridors for MADYMO computer simulation model development, and defined statistical test target thresholds for model validation. Two simulation models were developed, with and without a headrest. The models validated well for tiedown loads, wheelchair acceleration, lap belt loads and chest acceleration. Outcomes related to head and neck response were not as strongly validated. Model ATD neck response characterization methods were developed. Finally, parametric sensitivity analyses were used to develop wheelchair and headrest design guidelines for pediatric manual wheelchairs in rear impact for front securement point loads, rear wheel loads and seatback loads. Pediatric injury outcome measure sensitivity to wheelchair, headrest and crash pulse parameters was evaluated. Neck injury criteria (Nij) was sensitive to headrest placement; resulting recommendations specify placing the headrest as close as possible to the back of the head, and top of the headrest pad should be at least 5 cm above the head center of gravity. Effects of stiffer 6-year old ATD neck response on injury risk outcome measures were evaluated and found to reduce likelihood of severe neck injury

Development, application, and reliability of methods for ergonomic workload assessments in production evaluation and workstation design

Ergonomics assessments of conditions for humans at workstations and in manufacturing processes are necessary to prevent work-related musculoskeletal disorders and enhance efficiency and quality. Many methods can be used for this from systematic observations to direct measurements and simulation. Investigations of the accuracy and reliability of many methods as well as comparisons between them have been performed, but there is still need for further work as well as development of new methods.The inter- and intra-rater reliability of the OCRA checklist was studied through eleven ergonomists’ risk-assessments of ten video-recorded work tasks on two occasions. The statistical analysis included several parameters of reliability of which Cohen\u27s linearly weighted kappa was the primary measure. The inter-rater agreement of the OCRA checklist was 39%, and the weighted kappa was 0.43; the intra-rater dittos were 45% and 0.52. This indicated that the OCRA checklist is a moderately reliable tool.A risk assessment approach for digital human modelling (DHM) was developed. The approach included a reference database of epidemiological relationships between directly measured exposure and related musculoskeletal disorders. For illustration, a case in manual assembly was simulated; exposures were calculated and compared to the reference data to indicate the risk of WMSDs. The application and detailed assessment would be helpful to prioritise among different design solutions.A 3D digital prototype laparoscopic robotic console was ergonomically evaluated using the DHM tool IMMA with 12 manikins representing anthropometries of the Swedish and US population. Work-ranges of the console and the manikins were calculated, compared and ergonomically assessed using the Swedish standards and a US checklist for computer work. The assessment criteria related to the adjustable ranges of the screen height, height of the armrest, adjustable range of the pedals were not fulfilled. The DHM tool IMMA provides the possibility for a pre-production assessment of static work tasks

Finite Element Simulation Of The Offset-Deformable Barrier Euro NCAP Crash Test Reproduction On A HYGE Sled For Assessing Ten-Year-Old Child Safety

This research focuses on the definition of the guidelines to simulate a sled test which reproduces the ODB Euro NCAP crash test, using LS-DYNA Finite Element code. In addition, the last sections are based on the validation of the model, comparing numerical results with those of an experimental sled test performed with the same equipment in late 2018, and on a sensitivity study on the friction coefficient of a virtual slip ring. Several FE models have been utilized, to represent vehicle body, seats and restraint system with LS-DYNA. The subject of the test is a ten-year-old child dummy (Q-series Q10), placed on a booster seat in the second-row seat of the vehicle. Both experimental and numerical dummies were provided by Humanetics®. All the pre-processing steps needed to perform this kind of simulation have been described throughout this thesis. The most investigated step was the generation and calibration of the virtual restraint system, built utilising ANSA by BetaCAE. The LS-DYNA pretensioner and retractor were calibrated using different data from the experimental test as reference. The model was verified and validated computing cumulative error and validation metric. The head accelerations showed values of V equal to 78, 79 and 76% respectively, reasonably predicting the trend of the experimental curves. Additionally, the HICs have been well predicted, with coincident time instants and peak relative error below 15%. Chest and pelvis accelerations were predicted with an average V equal to 85%, constituting the areas of highest performance of the FE model. Upper neck forces and moments displayed an acceptable level of prediction, with V at least equal to 70%, whereas the lower neck showed the lowest correlation of the results, mostly on x and z-moments. It is important to underline that all biomechanical data in this thesis document were normalized for confidentiality reasons. Lastly, a sensitivity study on the influence of the dynamic friction coefficient FC of the lower LS-DYNA slip ring on the dummy injury responses was performed, obtaining a more correlated operation of the belt with respect to the experimental setting. The analysis was performed comparing all values of E and V among the different configurations, concluding that the most correlated setting has FC = 0.4, with an increase in V of 10% in the upper neck region

Lombalgia: strategie di prevenzione nei tassisti

Background E' noto che la lombalgia è un fenomeno diffuso e crescente, soprattutto nei paesi industrializzati, tanto da essere un fenomeno studiato e monitorato da tempo, anche in ambito lavorativo. Le dimensioni del problema sono tali da rendere la lombalgia il più comune disturbo muscolo-scheletrico della popolazione, con tassi d'incidenza del 80% nel corso della vita. Un recente sondaggio effettuato dalla comunità europea sulle condizioni lavorative, rivela che il 30% dei lavoratori europei soffre di dolori alla schiena e che il tasso di ricorrenza nell'arco dell'anno è piuttosto alto, attestandosi fra il 20 e il 44%, con ricorrenze nell'arco della vita fino all85%. Fra gli autisti e coloro i quali guidano veicoli per professione la prevalenza di LBP è alta, con valori quasi doppi rispetto ai lavoratori sedentari. L'aspetto più importante è che la lombalgia è stata riconosciuta come una delle maggiori cause di diminuzione dell'efficienza lavorativa e del benessere dell'individuo con conseguenti implicazioni finanziare, mediche e socioeconomiche sull'individuo nella sua quotidianità e sul piano lavorativo. Assenza lavorativa, cambio di lavoro, limitazioni lavorative, diminuita produttività e perdita del lavoro costituiscono alcune delle più note implicazioni socioeconomiche della lombalgia. Scopo dello studio Si è voluto innanzitutto circoscrivere e conoscere i fattori di rischio di una determinata categoria professionale, i tassisti, rappresentativa del settore dei trasporti e indagata più di altre in letteratura. Si è voluto indagare le principali strategie preventive adottate in questo settore, con attenzione all'evidenza dell'efficacia delle stesse e alla loro fattibilità e identificando il ruolo che può avere un opuscolo. Infine, costruire, sulla base delle nozioni teoriche raccolte, un opuscolo dedicato specificamente alla categoria professionale indagata, al fine di massimizzarne gli effetti, soprattutto qualora venga utilizzato all'interno di un programma preventivo multidimensionale. Materiali e metodi La prima parte dello studio è stata definita da una indagine della letteratura, raccogliendo, attraverso un criterio sistematico, tutti gli articoli relativi a tre macro- 5 argomenti considerati: fattori di rischio, caratteristiche di interazione del corpo con l'ambiente di guida e le strategie preventive testate finora in questo settore. Con le nozioni ricavate dall'analisi della letteratura si delinea poi un questionario per un'indagine conoscitiva di alcuni elementi caratteristici dei tassisti al quale sarebbe stato destinato poi l'opuscolo, al fine di costruirlo il più aderente possibile ai loro bisogni. Risultati e discussione Dall'analisi della letteratura emerge un quadro di estrema complessità dove sono frequenti le lacune conoscitive e dove si riscontra una notevole asimmetria di indagine, poiché viene privilegiata l'indagine di alcuni aspetti sacrificandone altri. Oltretutto l'ambiente di guida presenta una serie di elementi distintivi da qualsiasi altro contesto lavorativo, in primis quello dei lavoratori sedentari da cui si tende a volte, in maniera semplicistica, a mediare informazioni e conclusioni. La genesi multifattoriale della lombalgia si interseca con i notevoli fattori di rischio lavorativi, confermando la necessita di strategie preventive su più fronti, cronicamente carenti di un'adeguata dimostrazione di efficacia. Nella definizione dell'opuscolo, non è stato possibile avvalersi dei risultati derivanti dall'analisi dei questionari raccolti poiché in numero largamente insufficiente per costituire una base conoscitiva statisticamente rilevante. L'utilizzo di un opuscolo come valido strumento di prevenzione trova giustificazione in alcuni studi analizzati dove la definizione di un modello comportamentale lavoratoredipendente fornisce le basi teoriche di riferimento

Vehicle and Traffic Safety

The book is devoted to contemporary issues regarding the safety of motor vehicles and road traffic. It presents the achievements of scientists, specialists, and industry representatives in the following selected areas of road transport safety and automotive engineering: active and passive vehicle safety, vehicle dynamics and stability, testing of vehicles (and their assemblies), including electric cars as well as autonomous vehicles. Selected issues from the area of accident analysis and reconstruction are discussed. The impact on road safety of aspects such as traffic control systems, road infrastructure, and human factors is also considered

Sitting behaviour-based pattern recognition for predicting driver fatigue

The proposed approach based on physiological characteristics of sitting behaviours and sophisticated machine learning techniques would enable an effective and practical solution to driver fatigue prognosis since it is insensitive to the illumination of driving environment, non-obtrusive to driver, without violating driver’s privacy, more acceptable by drivers

Recent Advances in Motion Analysis

The advances in the technology and methodology for human movement capture and analysis over the last decade have been remarkable. Besides acknowledged approaches for kinematic, dynamic, and electromyographic (EMG) analysis carried out in the laboratory, more recently developed devices, such as wearables, inertial measurement units, ambient sensors, and cameras or depth sensors, have been adopted on a wide scale. Furthermore, computational intelligence (CI) methods, such as artificial neural networks, have recently emerged as promising tools for the development and application of intelligent systems in motion analysis. Thus, the synergy of classic instrumentation and novel smart devices and techniques has created unique capabilities in the continuous monitoring of motor behaviors in different fields, such as clinics, sports, and ergonomics. However, real-time sensing, signal processing, human activity recognition, and characterization and interpretation of motion metrics and behaviors from sensor data still representing a challenging problem not only in laboratories but also at home and in the community. This book addresses open research issues related to the improvement of classic approaches and the development of novel technologies and techniques in the domain of motion analysis in all the various fields of application