Vehicle Seat Research Articles

Optimization of the Production Management of an Upholstery Manufacturing Process Using Lean Tools: A Case Study

This study aims to address the challenge of implementing Lean philosophy in Small and Medium Enterprises (SMEs) and fill the research gap regarding Lean application in vehicle seat upholstery maintenance/repairing processes. The Lean tools applied in a case study of an upholstery industry of vehicle seats were as follows: Value Stream Mapping, Spaghetti Diagram, Gemba, 5S, Standardized Work, Kaizen, Kanban, and Poka-Yoke tools. A Decision Support Method using Excel Microsoft 365 was developed for improved stock control. A GUT Matrix was formulated to prioritize improvement opportunities, aiding prompt decision-making. This systematic approach enabled the company to address critical areas requiring swift attention. The results of Lean tools implementation led to a process waste minimization around 47%, and the process Lead Time decreased by approximately 26%, resulting in a 33% production increase. Thus, the Lean tools integration leads to substantial waste reduction, shorter process time, and increased production. The Decision Support Method enabled the company to efficiently monitor and manage its stock levels, thereby enhancing inventory management practices. This case study outlines the successful optimization of an upholstery production process in an SME by effectively applying Lean tools, highlighting its feasibility and benefits.

Fatigue life analysis of fillet weld with root gap in bogie tie rod seat under road traffic load

The results of failure analysis on the fillet welds of the tie rod seat in HDX2 type vehicle showed that size of root gap around cracks was usually larger than that observed in the region without cracks. Dynamic strain gauges were used to measure the time-strain curve of the zone surrounding the fillet weld in the locomotive traveling process. Then, a transfer matrix was utilized to calculate the time-strain curve of fillet welds and then a rainflow counting method was adopted to obtain hierarchical load spectra in the traveling process, which was used for predicting fatigue damage of fillet welds and safe service mileage. To reveal the influence of the root gap on the fatigue life of fillet welds, a three-factor and five-level orthogonal scheme was designed by taking the height, width and length of the root gap as variables. The calculation results based on road traffic loads indicated that: (1) When there is no gap at the root of fillet weld, the safe service mileage can meet standard requirements; when there is a gap at the root of the fillet weld, the safe service mileage is significantly shortened; (2) When the width, height or length of the root gap of fillet weld increases, the safe service mileage decreases monotonously. Given the same change in size, effect of the change in height of root gap on safe service mileage is the most significant among the three variables considered; (3) The maximum stress at straight line section of weld path was significantly greater than that at the corner section; (4) An inspection and maintenance program for root gaps of various sizes was developed.

Experimental design and optimization of pneumatic low-frequency driver seat for off-road vehicles: quasi-zero negative stiffness and gray wolf optimization algorithm

Experimental design and optimization of pneumatic low-frequency driver seat for off-road vehicles: quasi-zero negative stiffness and gray wolf optimization algorithm

Study on the psychological stress of occupants experienced by vehicle seat vibration in idle state via center of gravity sway measurement

This study aimed to quantitatively evaluate the factors that influence variations in psychological stress caused by seat vibrations. We employed the center of gravity sway measurements, a metric extensively studied in the realm of motion sickness. Our approach encompassed experiments and analyses to measure whole-body vibrations, scrutinize physiological responses, and assess the center of gravity sway. Our findings highlighted that the seat's vibration characteristics and their transmission to the occupant varied according to the occupant's center of gravity sway traits. We formulated a hypothesis to elucidate the correlation between the psychological stress induced by seat vibration and the nuances of the center of gravity sway. This theory was substantiated through correlation analysis. Involving 20 subjects, correlation analysis results showed a correlation between the peak strength of the PSD for the center of gravity sway's time variation around 2 Hz, the transmitted vibration, and the psychological stress deduced from electroencephalography (EEG) readings.

Integrating biomechanics with stakeholder perspectives to inform safety in grassroots dirt track racing

Grassroots dirt track racing is a foundational part of motorsports with a high risk of severe injury. This study aimed to gather perspectives and experiences of motorsports drivers surrounding safety and head acceleration events experienced during grassroots dirt track racing to inform strategies to improve driver safety. Thirteen drivers (n=9 who primarily race on dirt tracks; n=4 who primarily race on pavement tracks) with prior dirt track racing experience participated in separate, group-specific focus groups and/or one-on-one interviews where video, simulations of head motion, and head acceleration data were shared. Peak kinematics of laps and crash contact scenarios were recorded, and head perturbations (i.e., deviations in head motion relative to its moving-average trajectory) were quantified for each lap and presented through guided discussion. Responses were summarized using Rapid Assessment Process. Audio recordings and field notes were collected from focus groups and interviews and analyzed across 25 domains. Drivers described dirt track racing as short, fast bursts of racing. Benefits of dirt track racing for driver development were described, including learning car control. Drivers acknowledged risks of racing and expressed confidence in safety equipment but identified areas for improvement. Drivers observed lateral bouncing of the head in video and simulations but recognized that such motions were not noticed while racing. Track conditions and track type were identified as factors influencing head perturbations. Mean PLA (5.5 g) and PRV (3.07 rad/s) of perturbations experienced during racing laps and perturbation frequencies of 5 and 7 perturbations per second were reported. Generally, drivers accurately estimated the head acceleration magnitudes but were surprised by the frequency and maximum magnitude of perturbations. Maximum perturbation magnitudes (26.8 g and 19.0 rad/s) were attributed to hitting a “rut” in the dirt. Drivers described sudden stops, vertical loads due to landing from a large height, and impacts to the vehicle frame as crash events they physically feel the most. Summary statistics for crashes (medians = 7.30 g, 6.94 rad/s) were reported. Typical impact magnitudes measured in other sports (e.g., football) were provided for context. Upon reviewing the biomechanics, drivers were surprised that crash accelerations were relatively low compared to other contact/collision sports. Pavement drivers noted limited safety features in dirt track racing compared to pavement, including rigidity of vehicle frames, seat structure, seatbelt integration, and lack of oversight from sanctioning bodies. Most drivers felt seat inserts and head and neck restraints are important for injury prevention; however, usage of seat inserts and preferred head and neck restraint system differed among drivers. Drivers described their perspectives and experiences related to safety and identified strategies to improve safety in grassroots dirt track racing. Drivers expressed support for future safety research.

Optimizing frontal impact occupant protection systems for passengers seated in wheelchairs

ObjectiveThe advent of automated vehicles (AVs) provides an opportunity to design integrated wheelchair seating stations that provide an equivalent level of safety for occupants using wheelchairs as those using vehicle seating. This study designed a frontal occupant protection system for an integrated second-row wheelchair seating station that includes optimized airbags and seatbelt systems. MethodsMADYMO models were used to optimize belt geometry for a midsized male ATD seated in a surrogate wheelchair fixture, with and without inclusion of a Self Conforming Rearseat Air Bag (SCaRAB). Sled tests were performed to confirm the benefits of airbag use and optimized belt geometry. Additional modeling was performed with commercial manual and power wheelchairs, to identify the effects of wheelchair design and forward clear space on occupant kinematics and injury measures. Additional sled tests were performed with manual and power wheelchairs to demonstrate effectiveness of the restraint system with commercial products. ResultsSimulations and tests both showed improved kinematics using an optimized seatbelt system geometry compared to a commonly used suboptimal D-ring location that places the shoulder belt at a more outboard location. Use of the SCaRAB helped compensate for suboptimal geometry. Results include specific recommendations for belt geometry relative to the wheelchair seating station and airbag parameters suitable for protecting occupants seated in wheelchairs. Restraint systems initially optimized using the surrogate wheelchair also performed well with the two commercial wheelchairs. The clear space required for maneuvering a wheelchair will likely prevent injurious head contact in frontal crashes. ConclusionsThis study is the first to design a frontal optimal occupant protection system for an integrated second-row wheelchair seating station, demonstrating that it should be feasible once integrated wheelchair seating stations are included in AVs.

Adaptive Robust Active Vibration Control for Vehicle Seat Suspension with Unknown Passenger Mass

The vibration of the car seat can affect the comfort of passengers and can even cause some health hazards to them. In this paper, a vehicle seat control system is built to reduce the hazards of vehicle seat vibration. Firstly, the dynamic of the vehicle seat suspension is modelled. Then, an adaptive robust vibration control method is introduced: a base controller with an enhanced Youla parameterization is designed to turn it into a global stable controller set, followed by online tuning of the Q-parameters using an adaptive algorithm. The results of the vehicle seat vibration control were simulated in MATLAB/Simulink.

Star rating of driver’s behavior as a tool to prevent risky behavior

Driver behavior is a key determinant of road safety. Risky behaviors can be measured and quantified using traditional and modern methods, which enables the assessment of the driver’s behavior. Following lessons from safety science, it is important to analyse and manage risks factors to optimize interventions in the transport context at the territory. The main objective of the paper is to explore the star rating of the driver’s behavior to provide credible road safety monitoring and identification of the factors that most contribute to risky driving behaviors. The Data Envelopment Analysis method for selection of most significant factors is used for star rating of driver’s behavior. The subject of the analysis encompasses 18 factors for 27 police administration units (PAUs) in the Republic of Serbia. The results are analysed regarding the following aspects: 1) star rating of driver’s behavior and 2) defining the stages of the periodic factors monitoring for each PAU analysed. Using a mobile phone while driving, not using child restraints system, alcohol drunk driving during the night and seat belt use at rear seats of passenger vehicles were identified as the most significant factors associated with risky driving behaviors. Monitoring a broader set of factors helps to identify the strengths and weaknesses of a territory’s road safety system. Star rating of driver’s behavior as a tool intended for decision-makers ensures monitoring, management, the exchange of evidence-based and customized best practices and defining earlier goal-oriented actions to manage driver’s behavior and to prevent risky driving.

Repositioning forward-leaning passengers by seatbelt pre-pretensioning

Objective The study determined the seatbelt pre-pretensioner force needed and the time required to reposition average male front-seat passengers from forward-leaning to upright using finite element simulations of the Active SAFER Human Body Model (Active SHBM). Methods The Active SHBM was positioned in an initial forward-leaning position (29° forward from upright) on a deformable vehicle seat. A pre-pretensioner was modeled as a pre-loaded spring and its ability to reposition the forward-leaning Active SHBM to an upright position was simulated for twenty-four different pre-crash conditions. Four parameters were varied: (1) Automated Emergency Braking (AEB) active with 11 m/s2 or no AEB, (2) type of seatbelt system: Belt-In-Seat or B-pillar, (3) pre-pretensioner activation time (200 ms before, 100 ms before, or at the same time as AEB ramp-up), and (4) pre-pretensioner force (200 N, 300 N, 400 N, 600 N). The first thoracic vertebra fore-aft (T1 X) trajectories were compared against a reference upright position to determine the force and time needed to reposition and the effectiveness of repositioning in the different conditions. Results The lowest force enabling repositioning in all simulations was 400 N (no AEB, Belt-In-Seat). It took about 350 ms. In the presence of AEB, activating the pre-pretensioner 200 ms before AEB and using 600 N pre-pretensioner force was needed for repositioning (taking 200 ms with Belt-In-Seat and 260 ms with B-pillar installations). Repositioning was faster and thus more effective with the Belt-In-Seat seatbelt in all simulations. Conclusions All four parameters (presence of AEB, type of seatbelt system, pre-pretensioner activation time and force) affected the repositioning ability and time required. Far from all combinations repositioned a forward-leaning average male occupant model, but those found to be effective and fast appear as a feasible option for vehicle safety systems to reposition out-of-position occupants during pre-crash events.

Ride comfort and segmental vibration transmissibility analysis of an automobile passenger model under whole body vibration

The examination of seated occupants’ ride comfort under whole-body vibration is a complex topic that involves multiple factors. Whole-body vibration refers to the mechanical vibration that is transmitted to the entire body through a supporting surface, such as a vehicle seat, when traveling on rough or uneven surfaces. There are several methods to assess ride comfort under whole-body vibration, such as subjective assessments, objective measurements, and mathematical models. Subjective assessments involve asking participants to rate their perceived level of discomfort or satisfaction during the vibration exposure, typically using a numerical scale or questionnaire. Objective measurements include accelerometers or vibration meters that record the actual physical vibrations transmitted to the body during the exposure. Mathematical models use various physiological and biomechanical parameters to predict the level of discomfort based on the vibration data. The examination of seated occupants ride comfort under whole-body vibration has been of great interest for many years. In this paper, a multi-body biomechanical model of a seated occupant with a backrest is proposed to perform ride comfort analysis. The novelty of the present model is that it represents complete passenger by including thighs, legs, and foot which were neglected in the past research. A multi-objective firefly algorithm is developed to evaluate the biomechanical parameters (mass, stiffness and damping) of the proposed model. Based on the optimized parameters, segmental transmissibilities are calculated and compared with experimental readings. The proposed model is then combined with a 7-dofs commercial car model to perform a ride comfort study. The ISO 2631-1:1997 ride comfort standards are used to compare the simulated segmental accelerations. Additionally, the influence of biomechanical parameters on most critical organs is analyzed to improve ride comfort. The outcomes of the analysis reveal that seated occupants perceive maximum vibration in the 3–6 Hz frequency range. To improve seated occupants' ride comfort, automotive designers must concentrate on the pelvis region. The adopted methodology and outcomes are helpful to evaluate protective measures in automobile industries. Furthermore, these procedures may be used to reduce the musculoskeletal disorders in seated occupants.

LQR force command planning–based sliding mode control for active suspension system

In this article, a linear quadratic regulator (LQR)-based sliding model control strategy was proposed for the commercial vehicle seat suspension system. First, the multiple degrees of freedom mechanical dynamics model of a quarter suspension system was built. Then, the LQR force command planner was designed based on mechanical dynamics to ensure driver comfort. Second, considering the mechanical dynamics augmented with hydraulic actuator dynamics, a proportional-integral sliding mode control strategy was developed to track the reference force, which was calculated by the LQR force command planner in real time. Taking the problems of noise disturbances and unavailable full states feedback into consideration, the Kalman filter and tracking differentiator were designed and integrated into the control algorithm. Finally, the quarter suspension AMESim model was built, and the proposed control strategy was implemented and verified in the AMESim-Matlab/Simulink co-simulation environment. Comprehensive simulations were carried out. The simulation results, both from time domain and frequency domain perspective, indicated that the seat ride comfort can be effectively improved with the proposed method.

Tracking Occupant Activities in Autonomous Vehicles Using Capacitive Sensing

Autonomous vehicles (AV) are a promising contemporary engineering innovation. Since they have no human drivers, their vehicle controllers must be fully informed of the activities of their occupants in vehicle seats so that occupant safety and comfort can be guaranteed. This paper introduces a system that employs capacitive sensing and machine learning to inform the controller of occupant activities, like actions and posture changes. The system facilitates capacitive sensing by deploying a capacitance-sensing mat on the vehicle seat. A sensing circuitry connected to the mat measures all its capacitances continuously. Since an occupant’s body induces variations in these capacitances, temporal sequences of capacitance measurements represent various occupant activities in the vehicle seat. Subsequently, the system converts capacitance measurements corresponding to every time step to two grayscale capacitance-sensing images (CSIs). The CSIs, in turn, yield a feature vector corresponding to every time step, thereby building a dataset of temporal sequences of features. The system’s machine-learning unit tracks and recognizes occupant actions and posture changes using an action-recognition block, which is essentially a long short-term memory (LSTM) network trained on a dataset of temporal sequences of either features or capacitance measurements corresponding to various occupant actions. If the occupant remains stationary, a switching block in the unit disables the action-recognition block and enables a posture-recognition block. The latter is a k -nearest-neighbor ( k NN) classifier trained on a dataset of features to recognize stationary occupant postures. This paper validates the system’s performance and investigates its deployment for real-time tracking of occupant activities in AVs.

Random Vibration and Noise Analysis of Vehicle Seat Using Numerical Method

The development of vehicle seat used is a challenging task for the automotive industry. In this research the safeness of automotive seats by structural analysis and a random vibration analysis were studied. Hence, the main objective of this study is to determine the suitable vehicle seat configuration based on Noise, Vibration, and Harshness (NVH) performance. In order to achieve this objective, CFD software which is ANSYS was used to analyse frequency and deformation using different force distributed and different material on seat vehicle structure which the force applied from 250 N until 1000 N. The material used is aluminium alloy, magnesium alloy and structural steel to analyse the strength of seat structure. At the end of the study, the effect of different types of material vehicle seat structure was studied. The results confirm that by changing the seat structure material, the rattle noise and in general BSR noise can be improved or controlled accordingly. Consequently, for the seat system which has an identifiable structural dynamic, the BSR noise can be managed and controlled in early design phase by using the seat CAE model.

Frontal-oblique impact sled tests of a rearward-facing child restraint system with and without a support leg

ObjectiveTo quantify the head and neck injury metrics of an anthropometric test device (ATD) in a rearward-facing child restraint system (CRS), with and without a support leg, in frontal-oblique impacts. MethodsSled tests using the Federal Motor Vehicle Safety Standards (FMVSS) 213 frontal crash pulse (48 km/h, 23 g) were performed with a simulated Consumer Reports test buck, which comprised a test bench that mimics the rear outboard vehicle seat of a sport utility vehicle (SUV). The test bench was rigidised to increase durability for repeated testing and the seat springs and cushion were replaced every five tests. A force plate was mounted to the floor of the test buck directly in front of the test bench to measure support leg peak reaction force. The test buck was rotated 30° and 60° relative to the longitudinal axis of the sled deck to represent frontal-oblique impacts. The door surrogate from the FMVSS 213a side impact test was rigidly attached to the sled deck adjacent to the test bench. The 18-month-old Q-Series (Q1.5) ATD was seated in a rearward-facing infant CRS, which was attached to the test bench with either rigid lower anchors or a three-point seatbelt. The rearward-facing infant CRS was tested with and without a support leg. Conductive foil was attached to the upper edge of the door panel and a strip of conductive foil was attached to the top of the ATD head so that a voltage signal quantified contact with the door panel. A new CRS was used for each test. A repeat test was performed for each condition for a total of 16 tests. Data sourcesResultant linear head acceleration 3 ms clip; head injury criterion 15 ms (HIC15); peak neck tensile force; peak neck flexion moment; potential difference between the ATD head and the door panel; support leg peak reaction force. ResultsThe presence of a support leg significantly reduced head injury metrics (p < 0.001) and peak neck tensile force (p = 0.004) compared to tests without a support leg. Rigid lower anchors were associated with significant reductions in head injury metrics and peak neck flexion moment (p < 0.001) compared to tests that attached the CRS with the seatbelt. The 60° frontal-oblique tests had significantly elevated head injury metrics (p < 0.01) compared to the 30° frontal-oblique tests. No ATD head contact with the door was observed for 30° frontal-oblique tests. The ATD head contacted the door panel in the 60° frontal-oblique tests when the CRS was tested without the support leg. Average support leg peak reaction forces ranged from 2167 to 4160 N. The 30° frontal-oblique sled tests had significantly higher support leg peak reaction forces (p < 0.001) compared to the 60° frontal-oblique sled tests. ConclusionsThe findings of the current study add to the growing body of evidence regarding the protective benefits of CRS models with a support leg and rigid lower anchors.

What influences people to choose ridesharing? An overview of the literature

ABSTRACT Ridesharing is a shared mobility service in which passengers and drivers with similar origins and destinations are matched to travel in the same vehicle. This service utilises unused seats in vehicles and multi-passenger rides to reduce the cost of travel. To promote ridesharing, both service providers and policymakers should carefully analyse passenger adoption behaviour to support future decision-making and planning. In this paper, 80 studies on passenger ridesharing behaviour published since 2004 are reviewed. The motivating factors and barriers are analysed and classified in terms of demographic factors, psychological factors, and situational factors, and boundary conditions are included. The work provides a corresponding research framework on ridesharing behaviour. Finally, the current literature gaps are summarised and research recommendations are provided. This study provides a comprehensive and systematic research basis for ridesharing studies, and presents important theoretical and practical contributions to guide sustainable ridesharing behaviour.

The effect of reclined seatback angles on the motion of booster-seated children during lateral-oblique low-acceleration impacts

Belt-positioning boosters (BPB) may prevent submarining in novel seating configurations such as seats with reclined seatbacks. However, several knowledge gaps in the motion of reclined child occupants remain as previous reclined child studies only examined responses of a child anthropomorphic test device (ATD) and the PIPER finite element (FE) model in frontal impacts. The aim of this study is to investigate the effect of reclined seatback angles and two types of BPBs on the motion of child volunteer occupants in low-acceleration far-side lateral-oblique impacts.Six healthy children (3 males, 3 females, 6–8 years, seated height: 66±3.2 cm, weight: 25.2±3.2 kg) were seated on two types of low-back BPB (standard and lightweight) on a vehicle seat and restrained by a 3-point simulated-integrated seatbelt on a low-acceleration sled. The sled exposed the participants to a low-speed lateral-oblique (80° from frontal) pulse (2 g). Three seatback recline angles (25°, 45°, 60° from vertical) with two BPB (standard and lightweight) were tested. A 10-camera 3D-motion-capture system (Natural Point Inc.) was used to capture peak lateral head and trunk displacements and forward knee-head distance. Three seat-belt load cells (Denton ATD Inc) captured peak seatbelt loads. Electromyography (EMG, Delsys Inc) recorded muscle activation. Repeated Measure 2-way ANOVAs were performed to evaluate the effect of seatback recline angle and BPB on kinematics. Tukey’s post-hoc test for pairwise comparisons was used. P-level was set to 0.05.Peak lateral head and trunk displacement decreased with the increasing seatback recline angle (p < 0.005, p < 0.001, respectively). Lateral peak head displacement was greater in the 25° compared to the 60° condition (p < 0.002) and in the 45° condition compared to the 60° condition (p < 0.04). Lateral peak trunk displacement was greater in the 25° condition than the 45° condition (p < 0.009) and the 60° condition (p < 0.001), and in the 45° condition than the 60° condition (p < 0.03). Overall peak lateral head and trunk displacements and knee-head forward distance were slightly greater in the standard than the lightweight BPB (p < 0.04), however these differences between BPBs were small (∼10 mm).Shoulder belt peak load decreased as the reclined seatback angle increased (p < 0.03): the shoulder belt peak load was statistically greater in the 25° condition than the 60° condition (p < 0.02). Muscle activation from the neck, upper trunk, and lower legs showed great activation. Neck muscles activation increased with the increase in seatback recline angle. Thighs, upper arms, and abdominal muscles showed small activation and no effect of conditions.Child volunteers showed decreased displacement suggesting that reclined seatbacks placed the booster-seated children in a more favorable position within the shoulder belt in a low-acceleration lateral-oblique impact, compared to nominal seatback angles. BPB type seemed to minimally influence the children’s motion: the small differences found may have been due to the slight difference in heights between the two BPBs. Future research with more severe pulses is needed to better understand reclined children’s motion in far-side lateral-oblique impacts.

Innovative Approaches for Tackling Tax Evasion in the South African Minibus Taxi Industry: Lessons from Ghana, Zambia, and Zimbabwe

In South Africa, minibus taxis are a crucial mode of public transport for many commuters and a vital informal business sector with an estimated value of R90 billion. Concerns have been raised that the South African Revenue Service (SARS) is not collecting the optimal amount of tax revenue from this industry, with estimated tax collection at only R5 million in 2021. As a result of concerns that this industry might be involved in tax evasion or massive tax avoidance, this study investigates the taxation of minibus taxis in South Africa and explores alternative tax regimes that could be implemented to improve revenue collection. The study compares the current South African turnover tax system for minibus taxi operators to other African tax systems and evaluates a viable alternative tax regime or tax collection system. To improve tax collection from the industry, South Africa could consider a tax system tailored to the industry’s informal nature, utilising metrics such as vehicle seating capacity or distance travelled. A standardised tax system for small, medium, and micro enterprises may not be suitable. Consultation with industry stakeholders is essential for the proposed tax system to be acceptable. The study’s findings could inform South Africa’s National Treasury in creating a tax structure or collection scheme targeting the minibus taxi industry. This could increase tax revenue collection from the industry and support government expenditure, including income and wealth redistribution. This study distinguishes itself from prior publications on the South African minibus taxi industry by addressing tax compliance and collection challenges. It offers recommendations for alternative tax regimes to mitigate these challenges.

Characterizing neck and spinal response in booster seated reclined children in frontal impacts

Objective Belt-positioning booster seats (BPB) and pre-pretensioner (PPT) belts may be effective in preventing injuries from submarining and head excursion in reclined children. It is unknown if injuries at the neck and spine could still occur. This study’s goal is to characterize neck and spine responses in reclined children with and without the BPB and the PPT. Methods Eleven frontal impact sled tests were performed (56 kph) with the Large Omnidirectional Child (LODC) dummy on a production vehicle seat. A 3-point simulated seat-integrated-belt was used with a load-limiter (∼4.5 kN). Testing was conducted with and without the BPB with the seatback at ∼25°, ∼45° and repeated once. One test was conducted at ∼60° with the BPB. 100 mm of belt-slack was removed to simulate PPT in two 45° BPB tests and the BPB 60° test. The LODC peak thoracic spine accelerations and angular rotations, and peak neck and lumbar force/moment loads were compared between conditions. Results Neck shear forces were the highest in the 60° BPB & PPT (−1.9 kN) and 45° noBPB (−1.3 kN) than all other BPB conditions (−0.5 to −0.8 kN). The highest peak neck moments were found in the 45° noBPB (−40.5 N-m), and in the 60° BPB & PPT (−34.2 N-m) conditions compared to all others (−20.8 to −27.9 N-m.). The 60° BPB and PPT condition demonstrated thoracic forward rotation similar to the 25° noBPB condition (25° noBPB −24.8 to −35.0 deg, 60° BPB&PPT −27.5 to −43.2 deg.). Thoracic spine peak resultant accelerations (T1, T6, T12) were higher in the 25° and 45° noBPB conditions (53 g to 71 g) and in the 60° BPB & PPT (T6: 61.8 g) compared to all other BPB conditions (48.4 g to 53.1 g). The lumbar peak shear forces and moments were the highest in the 45° noBPB (4.9 kN, −296 N-m) and the 60° BPB & PPT condition (1.7 kN, −146 N-m). Conclusion These findings show similarities in neck, spine, and lumbar responses between the 60° reclined condition with BPB and PPT and the 25° and 45° conditions without the same countermeasures. This study highlights the need for future restraint developments to protect moderate and severe reclined BPB-seated child occupants.

Railways Passengers Comfort Evaluation through Motion Parameters: A Systematic Review

Railways are one of the most widely used mass transportation systems. Its superior transportation capacity, low environmental impact, high safety, and comfort have been leading to a continuous increase in passengers. To keep this trend going, it is crucial to improve the railways’ attractiveness and comfort levels. A rail journey’s comfort performance is rather complex, involving the analysis of multiple factors. Those raised by the vehicle motion and seat performance are the focus of vehicle designers’ concerns. Therefore, only a combination of static and dynamic comfort methodologies can accurately characterize passengers’ comfort. This work aimed to perform a systematic review concerning the comfort evaluation of train passengers. The bibliographic search yielded 62 studies on static and dynamic comfort evaluation methods. Results show a lack of experiments conducted on real rail environments, leading to weak conclusions regarding the real in-service conditions that train users face. Moreover, an investigation gap concerning the simultaneous application of both static and dynamic methodologies was observed. Therefore, more investigations are needed to evaluate and increase passengers’ comfort and promote rail usage as a daily transportation system.

Effects of an integrated safety system for swivel seat arrangements in frontal crash.

Objective: Autonomous vehicles (Avs) have paved the way for the arrangement of swivel seats in vehicles, which could pose a challenge to traditional safety systems. The integration of automated emergency braking (AEB) and pre-pretension (PPT) seatbelts improves protection for a vehicle's occupant. The objective of this study is to explore the control strategies of an integrated safety system for swiveled seating orientations. Methods: Occupant restraints were examined in various seating configurations using a single-seat model with a seat-mounted seatbelt. Seat orientation was set at different angles, from -45° to 45° with 15° increments. A pretension was used on the shoulder belt to represent an active belt force cooperating with AEB. A generic full frontal vehicle pulse of 20mph was applied to the sled. The occupant's kinematics response under various integrated safety system control strategies was analyzed by extracting a head pre-crash kinematics envelope. The injury values were calculated for various seating directions with or without an integrated safety system at the collision speed of 20mph. Results: In a lateral movement, the excursions of the dummy head were 100mm and 70mm in the global coordinate system for negative and positive seat orientations, respectively. In the axial movement, the head traveled 150mm and 180mm in the global coordinate system for positive and negative seating directions, respectively. The 3-point seatbelt did not restrain the occupant symmetrically. The occupant experienced greater y-axis excursion and smaller x-axis excursion in the negative seat position. Various integrated safety system control strategies led to significant differences in head movement in the y direction. The integrated safety system reduced the occupant's potential injury risks in different seating positions. When the AEB and PPT were activated, the absolute HIC15, brain injury criteria (BrIC), neck injury (Nij), and chest deflection were reduced in most seating directions. However, the pre-crash increased the injury risks at some seating positions. Conclusion: The pre-pretension seatbelt could reduce the occupant's forward movement in the rotating seat positions in a pre-crash period. The occupant's pre-crash motion envelope was generated, which could be beneficial to future restraint systems and vehicle interior design. The integrated safety system could reduce injuries in different seating orientations.