Passenger Comfort Research Articles

Development and Validation of a Driving Simulator for Comfort Assessment

AbstractThe passenger’s comfort is of vital importance in today’s car, even more so in the future autonomous car. Its thorough analysis requires the use of objective measures, but the subjectivity of the passenger must also be considered. The relationship between both aspects is an uncommon research avenue, and could greatly benefit from the use of a vehicle simulator. This study use a simulator to replicate a journey with diverse characteristics that numerous passengers may experience (including engaging in different activities). The appropriate variables for a proper comfort analysis are determined in this study, resulting in a comprehensive database for the same purpose. Additionally, a passenger comfort based questionnaire is developed and applied to obtain the subjective assessment of different passengers. The results of these questionnaires help not only in the identification and study of the self perception of comfort by the passengers but also in the use of the simulator for comfort experiments. The detailed comparison between both the objective approach of signal analysis and the subjective approach of questionnaires that is performed thanks to the simulator creates a foundation for future research and narrows the existing research gap.

Electric Vehicle Thermal System Concept Development for Multiple Variants Using Digital Prototype and AI

The automotive industry is experiencing a surge in system complexity driven by the ever-growing number of interacting components, subsystems, and control systems. This complexity is further amplified by the expanding range of component options available to original equipment manufacturers (OEMs). OEMs work in parallel on more than one vehicle model, with multiple vehicle variants for each vehicle model. With the increasing number of vehicle variants needed to cater to diverse regional needs, development complexity escalates. To address this challenge, modern techniques like Model-Based Systems Engineering (MBSE), digitalization, and Artificial Intelligence (AI) are becoming essential tools. These advancements can streamline concept development, optimize thermal and HVAC system design across variants, and accelerate the time-to-market for next-generation EVs. The development of battery electric vehicles (BEVs) needs a strong focus on thermal management systems (TMSs) and heating, ventilation, and air conditioning (HVAC) systems. These systems play a critical role in maintaining optimal battery temperature, maximizing range and efficiency, and ensuring passenger comfort. This article proposes a digital prototype (DP) and AI-based methodology to specify BEV thermal system and HVAC system components in the concept phase. This methodology uses system and variant thinking in combination with digital prototype (DP) and AI to verify BEV thermal system architecture component specifications for future variants without extensive simulation. A BEV cabin cooling requirement of 22 °C to be achieved within 1800s at a high ambient temperature (45 °C) is required, and its verification is used to prove this methodology.

Design and analysis of folding mechanism for automotive seats based on space maximization

To solve the problem of maximizing space utilization of car folding seats within limited spatial constraints, a design method for space-maximizing four-bar folding seat hinges is proposed. First, we will investigate the existing types of car folding seats, identify the mainstream configurations, and determine the optimal position of the four-bar linkage hinge point based on the constraints present within the car using theoretical analysis methods. Secondly, kinematic and dynamic models of the four-bar linkage mechanism are established, followed by the formulation of kinematic and dynamic equations. Finally, numerical methods are employed to solve these equations and obtain the kinematic and dynamic characteristics. The results indicate that the design method proposed in the article, which aims to maximize the space of the hinge four-bar folding seat, is efficient and feasible. This approach optimizes the utilization of interior space and enhances passenger comfort while accommodating the folding function of the seat within the existing vehicle environment. This method holds significant engineering implications for the design of folding seats in similar types of vehicles.

A Brain Network Analysis Model for Motion Sickness in Electric Vehicles Based on EEG and fNIRS Signal Fusion

Motion sickness is a common issue in electric vehicles, significantly impacting passenger comfort. This study aims to develop a functional brain network analysis model by integrating electroencephalography (EEG) and functional near-infrared spectroscopy (fNIRS) signals to evaluate motion sickness symptoms. During real-world testing with the Feifan F7 series of new energy-electric vehicles from SAIC Motor Corp, data were collected from 32 participants. The EEG signals were divided into four frequency bands: delta-range, theta-range, alpha-range, and beta-range, and brain oxygenation variation was calculated from the fNIRS signals. Functional connectivity between brain regions was measured to construct functional brain network models for motion sickness analysis. A motion sickness detection model was developed using a graph convolutional network (GCN) to integrate EEG and fNIRS data. Our results show significant differences in brain functional connectivity between participants in motion and non-motion sickness states. The model that combined fNIRS data with high-frequency EEG signals achieved the best performance, improving the F1 score by 11.4% compared to using EEG data alone and by 8.2% compared to using fNIRS data alone. These results highlight the effectiveness of integrating EEG and fNIRS signals using GCN for motion sickness detection. They demonstrate the model’s superiority over single-modality approaches, showcasing its potential for real-world applications in electric vehicles.

Acoustical properties of the new sandwich structures for aircraft cabin interiors with integrated vacuum insulation

AbstractAny modern passenger aircraft must provide a high level of comfort for passengers who spend considerable time inside the cabin. The cabin's climate and interior noise levels contribute to this comfort. Vacuum insulation panels (VIP) have been explored as insulation materials to improve these factors due to their extremely low thermal conductivity. When integrating VIPs into the aircraft cabin's interior, it was discovered that the thermal conductivity of the entire sandwich structure was 3–6 times lower than conventional structures. This finding has generated much interest in using VIPs for aircraft cabin insulation. This article delves into the acoustic properties of these new structures featuring integrated VIPs. Tests were carried out to analyze the sound insulation capabilities of these structures. The results showed that the new interior structures exhibited promising acoustic properties.

Structured acoustic materials for mitigating low-frequencybroadband aircraft noise: transfer matrix method

This study investigates, by numerical modeling, the mitigation of low-frequency broadband aircraft noise using a structured assembly of acoustic materials using the Transfer Matrix Method. The prevalence of low-frequency aircraft noise poses challenges to environmental sustainability and passenger comfort. The investigation focuses on an approach that employs strategically arranged structured acoustic materials to attenuate undesirable noise frequencies. The Transfer Matrix Method is used to model the acoustic behavior of the structured assembly, enabling a comprehensive analysis of sound transmission and absorption properties. This method supports the design and optimization of the assembly. The performance of the structured assembly to selectively attenuate low-frequency broadband noise is assessed through numerical simulations. The paper discusses implications for aircraft design, considering factors such as weight and cost. The benefits for environmental impact and passenger experience are also explored. Challenges and limitations in the implementation of structured acoustic materials are examined. The configuration studied presents an assembly of structured metamaterials arranged in series and in parallel which are integrated into a layer of glass wool. Present research contributes to the development of sustainable solutions for low-frequency aircraft noise. The structured assembly analyzed shows promise for significant noise reduction while considering practical constraints.

Psychoacoustic assessment of automotive fan-systems

In the automotive industry, electrification trends worldwide are inducing an increase of noise sources emergences. This reinforces the acoustic assessment metrics and thresholds set by stakeholders to ensure acoustic comfort of car passengers and passersby. The main acoustic indicator, the overall Sound Pressure Level, is not relevant enough to depict pedestrian annoyance during exposure to fan-system noises. Currently, psychoacoustic assessment of these products is not systematic as the psychoacoustic metrics taken separately are not sufficient for sound quality ranking. In order to address this weakness, studies were performed by Valeo based on fan-system noise jury evaluations. It aims at providing a preference model consisting of an equation which combines several psychoacoustic metrics to assess fan-system noise annoyance; keeping in mind that Loudness -or overall SPL- high levels could mask underlying annoyances biasing its assessment. In a first step, the correlation between Overall SPL, Loudness and aeraulic power is highlighted based on standard benchmark test database. In a second step, since tonal noises affect the perceived annoyance, additional tonal metrics are analyzed versus Loudness, or acoustic classes. Tonality especially is then compared to other tonal criteria, before potential assessment of a preference model equation.

The importance of different body parts for the (un-)pleasantness of whole-body vibration on an aircraft seat bench

Noise and vibration are two physical factors that can reduce the perceived comfort of passengers during a flight. To reduce the detrimental impact of seat transmitted vibration, it is necessary to understand which body parts and, thus, which corresponding seat parts are relevant for the pleasantness assessment. In this study, 40 participants (19 female, 21 male) rated the pleasantness of sinusoidal whole-body vibrations in the vertical direction while seated on a typical aircraft seat bench and listening to a synthetic broadband aircraft cabin noise over headphones. The vibration signals covered seven frequencies and four vibration levels, and pleasantness ratings were made on a verbally anchored scale. In addition, the participants separately marked those body parts that contributed significantly to their rating and those where they felt a vibration for each of the vibroacoustic stimuli. The results showed that not all body parts at which vibration were felt were also classified by the participants to reduce the ratings significantly, especially at higher vibration levels. A median split of the participants into groups of lighter and heavier participants indicates which body properties might be underlying factors for certain judgments.

An efficient strategy based on proper orthogonal decomposition for rapid determination of the location and rate of water vapor humidification in aircraft cabins

Currently, the air in commercial aircraft cabins during flights routinely exhibits extremely low relative humidity. But none of the previously published studies have addressed optimization of the humidification parameters in order to, create the desired humidity distributions in aircraft cabins at minimal cost. This study proposed an efficient strategy to accomplish the task. Under this strategy, a database of various potential humidification locations for aircraft cabins is first constructed. One scenario in the database is then selected by computational fluid dynamics (CFD)-based enumeration. Next, with the humidification location as prior information, the humidification rate and the air-supply temperature from the main ventilation system can be inversely designed by proper orthogonal decomposition. The above strategy was applied to a three-dimensional aircraft cabin model for the validated CFD cases. The results showed that an appropriate humidification for the cabin might both improve the thermal comfort of passengers and increase the humidity levels in the cabin; a decrease of the air-supply temperature from the main ventilation system would be beneficial in reducing the water vapor humidification rate required for passengers and allowing a higher humidification rate to be tolerated for the cabin walls. The parameters that improved the cabin air environment without significant moisture accumulation on walls were also provided by the proposed strategy. Compared with the full CFD simulation method, the proposed strategy is capable of providing accurate ranges of parameters while reducing the computing time by more than 95%, which demonstrates its competitive prospects.

Optimal Control of a Semi-Active Suspension System Collaborated by an Active Aerodynamic Surface Based on a Quarter-Car Model

This paper addresses the trade-off between ride comfort and road-holding capability of a quarter-car semi-active suspension system, collaborated by an active aerodynamic surface (AAS), using an optimal control policy. The semi-active suspension system is more practical to implement due to its low energy consumption than the active suspension system while significantly improving ride comfort. First, a model of the two-DOF quarter-car semi-active suspension in the presence of an active airfoil with two weighting sets based on ride comfort and road-holding preferences is presented. Then, a comprehensive comparative study of the improved target performance indices with various suspension systems is performed to evaluate the proposed suspension performance. Time-domain and frequency-domain analyses are conducted in MATLAB® (R2024a). From the time-domain analysis, the total performance measure is enhanced by about 50% and 35 to 45%, respectively, compared to passive and active suspension systems. The results demonstrate that a semi-active suspension system with an active aerodynamic control surface simultaneously improves the conflicting target parameters of passenger comfort and road holding. Utilizing the aerodynamic effect, the proposed system enhances the vehicle’s dynamic stability and passenger comfort compared to other suspension systems.

DIAGNOSTIC EVALUATION OF URBAN METRO TRANSIT SYSTEM POST-COVID-19

Public transportation usage in Delhi has declined, with the Delhi Metro having a significant share. However, due to fare hikes and COVID-19 restrictions, the DM's share has been decreasing further. To improve ridership, a study is being conducted to evaluate the DM's performance and identify areas for improvement in passenger convenience and comfort. The Magenta line is investigated through an on-board survey to collect primary data. The survey covers commuter perceptions of safety & security, financial & economic factors, infrastructure & comfort and functional & operational features. The Relative Importance Index approach is used to analyse the data and evaluate DM performance. An ANN model is also presented to determine the factors influencing the choice to travel on the DM, with the “metro fare per trip” factor being a key consideration. Based on the analysis results, recommendations are made to improve the DM's performance. The study found that safety and security had the highest RII, followed by efficiency and viability, functional and operational features, infrastructure and comfort, and financial and economic factors. The subway fare had the lowest RII. The ANN model is adapted to understand the reasons behind low metro ridership.

Диагностика системы взаимодействия железнодорожного пути и подвижного состава по параметрам комфорта езды и эквивалентной конусности

Purpose: to identify the influence of the geometric parameters of wheel sets and rail track on the smoothness of the ride and the level of passenger comfort for an automated diagnostic system. Methods: statistical methods were used to conduct the research. Sampling and analysis of statistical observation data made it possible to identify existing approaches to assessing the levels of interaction of the wheel-rail system at different speeds. The track sections grouped into rows along pickets were assessed in terms of passenger ride comfort and equivalent conicity. Materials used in the public domain and official websites, as well as research by the authors. Results: a list of factors influencing the conditions of interaction between highspeed rolling stock and the railway track has been identified. Data were obtained for indicators of ride comfort and equivalent conicity for the St. Petersburg — Moscow line along pickets at actual realizable speeds. Practical importance: the possibility of using remote measurement diagnostics to determine the geometric parameters of wheelsets and rails and the geometric parameters of the rail track has been determined. Suggestions for improving the qualitative assessment of the interaction of the wheel-rail system are recommended.

Failure analysis and optimization design of CFRP automotive seat back under multiple conditions

This study explores the adoption of carbon fiber reinforced plastic (CFRP) in automotive seat backrests, aiming to improve compliance with regulatory standards and enhance performance. By replacing conventional materials with CFRP, and employing mechanical performance tests alongside the principle of equal stiffness, the study tackles material failure issues. A novel multi-criteria decision-making method, coupled with an optimal Latin hypercube experimental design, is used to optimize the layup sequence. The optimized design not only meets regulatory requirements but also significantly enhances driver and passenger safety and comfort during collisions.

Experimental study on bioaerosols behavior and purification measures in a subway compartment.

Bioaerosols in public transportation systems raise critical environmental concerns, seriously threatening passenger health and safety. In this study, we investigate the spread characteristics of bioaerosols in a standard type-B subway compartment using both air sampling and sediment sampling methods. Additionally, without compromising indoor passenger comfort, two self-designed air purification devices, based on intense field dielectric (IFD) and dielectric barrier discharge (DBD) technologies, respectively, are successfully applied for the improvement of the subway air quality. The results show that bioaerosols can propagate rapidly throughout the entire compartment in 5min via airborne transmission. Under the effect of the symmetric air ducts and compartment structure, the difference in bioaerosol concentration in the air is less than 10% between both ends of the compartment. Concurrent substantial bioaerosol deposition on the ground, seats, and windows underscores the risk of contact transmission. Furthermore, the real-time purification rates of the two devices integrated into the air conditioning system reach 59.40% and 44.98%, respectively. With their demonstrated high efficiency in purifying bioaerosols and modular design featuring low energy consumption, easy cleaning, and reusability, these devices stand out as viable long-term solutions for large traffic vehicles. These research findings provide practical equipment recommendations and installation strategies for optimizing indoor air quality in subways and are applicable to other similar transportation systems.

ERGONOMIC AND LOGISTIC ENSURING THE REQUIREMENTS FOR THE COMFORT DURING THE ORGANIZATION OF PASSENGER TRANSPORTATION IN A SMALL-CAPACITY BUS

Purpose. The most important advantage of passenger transport by road is the high quality of transport service, which depends on the organization of the transport process, structural features and technical condition of the rolling stock used and the route, the development of the route network and other factors. Comfort reflects the properties of bus passenger transportation, which lead to the creation of the necessary service conditions and convenience for passengers in the bus, at the start-end and transit points on the basis of regulatory documents approved in the prescribed manner. Features of the design of small-capacity buses in terms of comfort and safety of passenger transportation and provision of proper travel conditions mostly determine the scope of use of buses of this class by types of connections and length of routes. The purpose of the paper is the development of a structural model, based on the analysis of the main factors affecting the determination of the comfort of a small-capacity bus for urban transportation during the transportation of passengers. Methods. The analysis of literary sources showed that indicators of comfort (as well as indicators of information service, speed, timeliness, safety of cargo, safety), which refer to indicators of the quality of passenger transportation, are decisive in this group of indicators. From the point of view of Ukrainian legislation and regulatory framework, the concepts of passenger bus capacity and comfort are analyzed. The main factors that determine the comfort of small-capacity buses for urban transportation during the transportation of passengers are determined. Ensuring the comfort of passenger transportation in a small-capacity city bus is determined by compliance with ergonomic requirements, which, in turn, depends on the design features of the arrangement of the area intended for passengers. Scientific novelty. It is proposed to evaluate the comfort category in the urban public road transport system using a structural model that combines two sets of factors – logistic and ergonomic. The logistic set of factors includes characteristics in time and space, that is, characteristics of comfort outside the means of urban public road transport. The ergonomic set of factors includes characteristics that describe comfort in vehicles. Practical significance. On the basis of this model, possible ways of ensuring ergonomic requirements for the layout of the interior and interior of small-capacity buses for urban passenger transportation are proposed. It was established that the main factors of the redistribution of transport mobility between urban passenger transport and transport for individual use are the insufficient comfort of passenger transport or the insufficient density of the route network.

Remote control of the technical condition of metro trains using seismological tools

As urban road congestion increases and people shift to using the subway, the safety of under-ground transportation becomes a priority. Therefore, it is necessary to establish a monitoring sys-tem for subway trains to detect malfunctions that occur during operation. The article proposes an engineering seismology method for remote monitoring of the technical condition of metro trains based on the analysis of micro seismic vibrations. This method allows remote control of the dynamic parameters of each train and their deviations from the norm. The authors demonstrate how a seismic recorder placed in a building adjacent to a metro station can be used to monitor changes in the amplitude-frequency spectrum of vibro seismic recordings. It is used to determine the arrival and departure times of trains, and it is shown that observations are best made for departures due to their more pronounced signal amplitude. The recorded signal of a metro train should fall within a certain frequency range, which is determined based on its average values, and any deviation of the observed signal spectrum from this norm indicates changes in the train's condition. The proposed approach not only helps improve passenger safety, but also reduces the risk of emergencies associated with technical malfunctions of rolling stock. In the future, it is possible to develop software equipped with a database of statistical data, which will allow even more efficient control of metro operations and prompt response to any deviations, thus ensuring a high level of safety and comfort for passengers.

Effect of Honeycomb Geometrical Parameters on Equivalent Radiated Power and Frequency Response of Motor Casing and Gearbox Surface of a Powertrain

ABSTRACTThe powertrain, as a central source of noise and vibration, is crucial in determining the overall NVH (noise, vibration and harshness) performance of vehicles, necessitating the optimisation of its structural components for improved durability and passenger comfort. This paper investigates the influence of key geometrical parameters—cell thickness, skin thickness and cell length—on the complex frequency modes of honeycomb and square sandwich structures using the Altair OptiStruct solver 2022 and fast Fourier transform analyser. The driven and non‐driven ends of a motor casing and a gearbox, represented by honeycomb structures and ribs, were subjected to an evaluation of equivalent radiated power (ERP). The results show that the square structure performs better at higher skin thickness when resisting severe lateral stresses than the honeycomb while being less stiff at higher cell thickness. Notably, smaller cell length had a substantial impact on the modes of the honeycomb structure, whereas larger cell length had an impact on the square structure. Response surface methodology was used to optimise the modal frequencies of both square and honeycomb panels simultaneously. An ideal cell length of 5.88 mm, skin thickness of 1.303 mm and cell thickness of 0.381 mm were found for the honeycomb construction, yielding a composite desirability of 0.981. On the other hand, with a cell length of 5.045 mm, skin thickness of 1.484 mm and cell thickness of 0.331 mm, the square structure achieved a composite desirability of 0.989. It is interesting to note that the driven end casing of the motor casing made more noise with the addition of ribs than the non‐driven end and gearbox. But compared to the original powertrain model, adding a honeycomb structure resulted in a noise reduction of about 10%.

Investigation of cabin heating in electric vehicles with integrating solar cells and heat storage systems

In recent years, the production and usage of electric vehicles have been encouraged due to zero emissions, efficiency, and economic factors. Efficient cabin heating and thermal management in electric vehicles are crucial for enhancing passenger comfort, extending battery life, and optimizing overall energy usage, thus contributing to the sustainability and practicality of electric transportation. Heating the cabin of electric vehicles in winter has a negative effect on range. Therefore, methods are being researched to use energy efficiently without sacrificing passenger comfort and minimizing the effect on the vehicle's range. This study presents an innovative radiator design specifically crafted for Electric Vehicles (EVs), leveraging solar panels to heat water for the radiator. This system enables the vehicle to harness solar energy for heating a water tank while stationary, effectively serving as an energy storage reservoir. Upon vehicle movement, the radiator system activates to disperse the stored thermal energy throughout the cabin, ensuring superior thermal comfort. Consequently, optimizing battery range is achieved as the heating load typically leads to significant range reductions. From the obtained results in experiment 2, the results indicated that the cabin temperature rose from 3 °C to around 15 °C within a few minutes, reflecting an increase of approximately 12 °C. According to the results, this indicates that there will be a reduction in energy consumption of between 1.9 % and 3 % for a one-hour travel range in this electric vehicle. The findings of this investigation demonstrate that utilizing warm water energy storage effectively enhances cabin thermal management.

Integrated battery thermal management and CO2 control in electric buses using recirculated air and waste heat recovery

In recent years, electric vehicles (EVs) have significantly progressed due to their environmental protection and energy-saving advantages. However, maintaining indoor thermal comfort and effective battery thermal management are critical considerations for EVs. Unlike conventional vehicles, EVs cannot use waste heat and depend on heat pump systems for winter heating and summer cooling. This research proposes a novel system to reduce the energy consumption of heat pump systems by using recirculated air while addressing the challenges of battery temperature management and maintaining safe CO2 concentrations in the cabin. The primary objectives of this research are threefold: first, to ensure passenger comfort through an integrated approach that includes cabin CO2 concentration safety; second, to recover heat from recirculated cabin air to save energy and control battery temperature; and third, to comprehensively analyze the performance of the Electric Vehicle Thermal Management System (EVTMS) using precise Computational Fluid Dynamics (CFD) analysis and mathematical modeling. This study will significantly enhance the understanding of energy consumption related to CO2 concentration control; an aspect previously overlooked in the literature. It will develop a battery temperature management strategy that leverages bus exhaust heat. These contributions will aid in achieving both passenger comfort and battery stability in electric buses, providing practical insights for the design and optimization of thermal management systems for future electric buses.

Dynamic response of high-speed trains under uneven temperature fields of slab tracks on cable-stayed bridges

The temperature deformation of a long-span cable-stayed bridge (LSCSB) could significantly deteriorate the smoothness of rails, thereby affecting the dynamic behavior of high-speed trains (HSTs). In this paper, based on the thermal-fluid-structure coupling theory and vehicle-track coupling dynamics theory, an analysis method was proposed to explore the influence of temperature deformation of LSCSBs on the dynamic behavior of HSTs. The temperature deformation of LSCSBs within a day was analyzed, and the dynamic behavior of HSTs passing through the LSCSBs at different times was revealed. The results showed that on a summer day, the temperature deformation of LSCSBs varied significantly and rapidly, and the variation experienced a significant increase of 23.46% within just 2 h. Due to the influence of structural temperature deformation, the wheel-rail interaction, train safety, and passenger comfort changed noticeably. The construction temperature of the bridge and track decisively affected the dynamic behavior of the train. Therefore, it was crucial to construct the structure under suitable temperature conditions to prevent further exacerbation of the dynamic behavior of HSTs due to violent temperature differentials. In summary, the method proposed in this paper could contribute to a comprehensive and in-depth understanding of the operational characteristics of HSTs on LSCSBs.