Occupant Restraint System Research Articles

Optimization study of tail-lateral occupant injury and restraint system for an off-road vehicle ramp rollover

The process of rollover accidents involving specialized vehicles is characterized by intense motion and long duration. Although these accidents are infrequent, they often lead to a high fatality rate. In this study, we utilized LS-Dyna software to simulate the rollover of a vehicle on a side ramp. This simulation aimed to verify the reliability of our model establishment by comparing the vehicle’s motion attitude and center-of-mass acceleration with experimental results. Additionally, we sought to investigate the lateral occupant injuries that occur in the tail section of a certain type of specialized vehicle during a rollover. Initially, we obtained the vehicle’s motion trajectory and the dummy’s motion state through simulation. Subsequently, we extracted the injury response of each part of the dummy. We then simplified the entire vehicle model and made improvements to the occupant restraint system, ultimately designing an enhanced system. Finally, we approximated and replaced the entire vehicle model by establishing an approximation model. We combined this with an optimization algorithm to optimize the occupant restraint system. The simulation results demonstrate that the improved occupant restraint system significantly reduces the axial force on the neck of the occupant and the comprehensive evaluation index of injury. Furthermore, the simulation results for each component fall below the injury limit value specified in the FMVSS208 crash occupant protection standard. Therefore, the improved occupant restraint system proposed in this study effectively mitigates lateral occupant injury during rollover accidents.

Optimization of Occupant Restraint System Using Machine Learning for THOR-M50 and Euro NCAP

In this study, we propose an optimization method for occupant protection systems using a machine learning technique. First, a crash simulation model was developed for a Euro NCAP MPDB frontal crash test condition. Second, a series of parametric simulations were performed using a THOR dummy model with varying occupant safety system design parameters, such as belt attachment locations, belt load limits, crash pulse, and so on. Third, metamodels were developed using neural networks to predict injury criteria for a given occupant safety system design. Fourth, the occupant safety system was optimized using metamodels, and the optimal design was verified using a subsequent crash simulation. Lastly, the effects of design variables on injury criteria were investigated using the Shapely method. The Euro NCAP score of the THOR dummy model was improved from 14.3 to 16 points. The main improvement resulted from a reduced risk of injury to the chest and leg regions. Higher D-ring and rearward anchor placements benefited the chest and leg regions, respectively, while a rear-loaded crash pulse was beneficial for both areas. The sensitivity analysis through the Shapley method quantitatively estimated the contribution of each design variable regarding improvements in injury metric values for the THOR dummy.

Performance evaluation of the eight-one six-point occupant restraint system based on experiments

In order to further ensure occupant safety, a new type of motor vehicle occupant restraint system is proposed in the paper. According to its structural characteristics, the shoulder belts are shaped like the Chinese number eight (八), the lap belt is shaped like the Chinese number one (一), and it has six fixed points; hence, it is called the “Eight-one six-point occupant restraint system.” The effectiveness of the “Eight-one six-point occupant restraint system” for adult and child occupant protection was verified under frontal impact conditions (50 km/h) and lateral impact conditions (30 km/h) using the Hybrid III 50th percentile dummy and the Q3 child dummy, respectively. Meanwhile, a comparison was made with the safety performance of the typical occupant system. The conclusion indicates that wearing a typical occupant restraint system carries the risk of occupant detachment from the restraint, neck strangulation, and collision interference between occupants on the far side and on the collision side; it also cannot be applied for child occupant protection. However, the “Eight-one six-point occupant restraint” can effectively restrain adult and child occupants within safety areas with a simple and easy-to-wear structure and technological innovation, which has certain application value.

Multi-Parameter and Multi-Objective Optimization of Occupant Restraint System in Frontal Collision

To solve the constraints of multi-objective optimization of the driver system and high nonlinear problems, according to the relevant dimensions of a car, we build a simulation model with Hybrid III 50th dummy driver constraint system. The comparison of the driver mechanics index of the experimental data with the simulation data in the frontal crash shows that the accuracy of simulation model meets the requirements. The optimal Latin test design is adopted, and the global sensitivity analysis of the design parameters is carried out based on the Kriging model. The four most sensitive parameters are selected, and the parameters are solved by a multi-island genetic algorithm. And then the nonlinear programming quadratic line (NLPQL) algorithm is used to search for accurate optimization. The optimal parameters of the occupant restraint system are determined: the limiting force value of force limiter 2 985.603 N, belt extension 12.684%, airbag point explosion time 27.585 ms, and airbag vent diameter 27.338 mm, with the weighted injury criterion (WIC) decreased by 12.97%, the head injury decreased by 22.60%, and the chest compression decreased by 7.29%. The results show that the system integration of passive safety devices such as seat belts and airbags can effectively protect the driver.

Multiobjective optimization design for an occupant restraint system considering interval correlation

Multiobjective optimization design for an occupant restraint system considering interval correlation

Views of American and Australian mobility device users and ambulant bus users regarding occupant restraint systems on public buses

IntroductionWith an ageing population, increasing numbers of people are using mobility devices, such as wheelchairs or scooters, whilst travelling on public route buses. The regulations and availability of active (wheelchair tie down and occupant restraint systems or WTORS) and passive (rearward facing) mobility device restraint systems on buses varies between countries. To date few studies have investigated passenger feedback on the use of restraint systems. This study aimed to gather feedback about WTORS on buses from passengers where these are in use (United States) and not in routine use (Australia) to guide decisions on their introduction. MethodsA prospective study using a purpose-designed electronic survey. Participants, predominantly recruited by Qualtrics, comprised two groups; mobility device and ambulant bus users in two countries; Australia and the United States (US). ResultsThe 448 participants rated the top two most important factors when deciding if buses should have WTORS as safety and comfort. Ninety-two percent of respondents believed people using mobility devices should use a WTORS which was rated 7.66/10 (SD1.97) as effective to prevent injuries to self or others. Only a minority of participants (13.2%) had ever slid or fallen from their mobility device, or seen a person slide or fall (13.6%) while on a bus with no differences between countries despite WTORS not being in use in Australia. Respondents reported it was OK to delay a journey an average of 5.52 (SD 2.89) minutes to secure/release a restraint system, which compares favourably to literature-reported real time of one to 4 min. ConclusionsAlthough WTORS were widely perceived by participants as important for safety, questions concerning their effectiveness to prevent slide or tip remain. Prior to the introduction of any securement system in Australia, the effectiveness of passive occupant containment systems to prevent slide or tip also warrants investigation.

A Literature Review of Wheelchair Transportation Safety Relevant to Automated Vehicles.

This literature review summarizes wheelchair transportation safety, focusing on areas pertinent to designing automated vehicles (AVs) so they can accommodate people who remain seated in their wheelchairs for travel. In these situations, it is necessary to secure the wheelchair to the vehicle and provide occupant protection with a Wheelchair Tiedown and Occupant Restraint System (WTORS). For this population to use AVs, a WTORS must be crashworthy for use in smaller vehicles, able to be used independently, and adaptable for a wide range of wheelchair types. Currently available WTORS do not have these characteristics, but a universal docking interface geometry and prototype automatic seatbelt donning systems have been developed. In the absence of government regulations that address this situation, RESNA and ISO have developed voluntary industry standards to define design and performance criteria to achieve occupant protection levels for wheelchair-seated passengers that are similar to those provided by conventional vehicle seats.

Stochastic Crashworthiness Optimization Accounting for Simulation Noise

Abstract Finite element-based crashworthiness optimization is extensively used to improve the safety of motor vehicles. However, the responses of crash simulations are characterized by a high level of numerical noise, which can hamper the blind use of surrogate-based design optimization methods. It is therefore essential to account for the noise-induced uncertainty when performing optimization. For this purpose, a surrogate, referred to as Non-Deterministic Kriging (NDK), can be used. It models the noise as a non-stationary stochastic process, which is added to a traditional deterministic kriging surrogate. Based on the NDK surrogate, this study proposes an optimization algorithm tailored to account for both epistemic uncertainty, due to the lack of data, and irreducible aleatory uncertainty, due to the simulation noise. The variances are included within an extension of the well-known expected improvement infill criterion referred to as Modified Augmented Expected Improvement (MAEI). Because the proposed optimization scheme requires an estimate of the aleatory variance, it is approximated through a regression kriging, which is iteratively refined. The proposed algorithm is tested on a set of analytical functions and applied to the optimization of an Occupant Restraint System (ORS) during a crash.

Advancement of Vehicle Occupant Restraint System Design by Integration Of Artificial Intelligence Technologies

Advancement of Vehicle Occupant Restraint System Design by Integration Of Artificial Intelligence Technologies

Multiobjective optimization on cooperative control of autonomous emergency steering and occupant restraint system for enhancing occupant safety

Occupant safety remains one of the most challenging and significant design considerations in the automotive and transportation industry. Nevertheless, independently developed active or passive safety systems may lead to unsatisfactory protective performance under the critical driving scenarios. This study aimed to conduct multiobjective optimization of the cooperative controls between autonomous emergency steering (AES) and occupant restraint system (ORS) to explore the potential occupant injury reduction capability as well as mechanisms subjected to a frontal collision. First, a multiple simulation approach comprising PreScan/Simulink, LS-DYNA, Madymo was used to correlate the control parameters of the safety systems and occupant injuries quantitatively. Then the control parameters of AES and ORS were selected as the design variables after sensitivity analysis, and injury responses of the sampling points were extracted by the multiple simulation approach. Surrogate models and multiobjective optimization algorithm were used to determine the optimum design in cooperative controls of AES and ORS maneuvers, from which in-depth effect mechanisms that contributed to the improvement of occupant protection were identified. Compared to the baseline design, the optimum control parameters of AES-ORS integration substantially decreased the occupant injuries of the head, chest and neck, and consequently led to a reduction of 33.02% in the overall injury risk. This study is anticipated to demonstrate a new design approach for the control system, thereby enhancing occupant safety.

Comparison of USA and Australian Mobility Device Users’ and Ambulant Bus Users’ Views of Restraints on Public Buses

Many older people use powered wheelchairs and mobility scooters to access the community on buses but have increased injury risk if the mobility device tips or slides. Wheelchair tie-down and occupant restraint systems (WTORS) are mandated on USA transit buses, and their introduction investigated in Australia. This study examined the views of mobility device and ambulant bus users in the USA and Australia on WTORS. A Qualtrics survey with 448 respondents showed strong support for WTORS use and found the most important factors underpinning use were Safety, Comfort, and Transit time. US research indicates dwell time while fitting WTORS is 4 minutes, and participants reported 5.65(SD3.06) minutes is acceptable. There was no difference in USA and Australian participants who have slid or tipped in their device, despite being restrained in the USA: X2(1,n=220)=.053,p=.53,phi-.016). This research suggests all bus users are supportive of WTORs, but their effectiveness requires investigation.

Occupant Restraint Systems do not Completely Prevent Injury at the Cranio-cervical Junction in a High-energy Accident

Advances in automobile crashworthiness have reduced both fatalities and severe injuries with different occupant restraint systems (seatbelts and airbags). However, even the appropriate use of these systems does not always completely prevent injury at the cranio-cervical junction in a high-energy accident. This report presents two such cases. Drivers should be educated not to place too much confidence in the safety provided by occupant restraint systems. In addition, physicians should pay attention to cranio-cervical trauma when a patient experiences cardiac arrest after a motor vehicle accident, even the patient is protected by occupant restraint systems.

Reliability-based optimization of a novel negative Poisson's ratio door anti-collision beam under side impact

Anti-collision beam of front door has significant influence on occupant protection and side crashworthiness. In order to improve the comprehensive side impact performance of vehicle, this work proposes a novel negative Poisson's ratio (NPR) door anti-collision beam based on star-shaped cellular structural material, and optimizes it by a reliability-based optimization scheme. First, the parametric model of NPR anti-collision beam, vehicle model assembling NPR beam, occupant restraint system model and side collision model are established. Then, the basic mechanical properties of the NPR structure are investigated under considering the axial normal force, transverse shear force and bending moment of each rod, and the macro performance of NPR beam are analyzed. Next, a deterministic optimization integrating optimal Latin hypercube sampling (OLHS) method, response surface model (RSM) and NSGA-II algorithm is conducted to improve the performance of novel NPR beam. Finally, considering the uncertainties of design variables, a reliability-based optimization is further executed to enhance the robustness of the deterministic optimization by using Design for Six Sigma (DFSS) method. Simulation results show that the ultimate optimized NPR anti-collision beam can not only ameliorate driver's protection and side crashworthiness, but also ensure the reliability and lightweight effect. • An NPR beam is proposed to protect occupant safety and structural integrity. • The performance of star-shaped NPR beam is investigated. • Reliability-based optimization is conducted to improve the overall performance.

A Preliminary Study on the Restraint System of Self-Driving Car

<div class="section abstract"><div class="htmlview paragraph">Due to the variation of compartment design and occupant’s posture in self-driving cars, there is a new and major challenge for occupant protection. In particular, the studies on occupant restraint systems used in the self-driving car have been significantly delayed compared to the development of the autonomous technologies. In this paper, a numerical study was conducted to investigate the effectiveness of three typical restraint systems on the driver protection in three different scenarios. It is found that based on the simulation results: (1) All the restraint systems are capable of providing effective protection for the driving driver and the 4-point belt restraint system has advantages due to its better protective effect on the occupant thorax; (2) When the driver is in half-reclining and reclining resting modes, head HIC<sub>36</sub>, neck N<sub>ij</sub> and chest compression are about 572.9-1524.3, 0.64-1.47, and 14.7-48.3 mm, respectively; These values are higher than those of a driving driver by 0.2%-198.3% for HIC<sub>36</sub>, 113.3%-359.4% for neck N<sub>ij</sub>, and -59.6%-79.8% for chest compression, respectively. (3) There is an evident “submarining” of dummy in the half-reclining and reclining resting modes. This study shows that the mainstream restraint system cannot meet the safety requirements for occupants with multi-postures in the self-driving cars. Smart restraint systems which can be actively adjusted for protecting occupants sitting in different postures are deemed to be necessary in case of unavoidable crashes.</div></div>

Investigation of risk factors affecting injuries in reclining seat under frontal impact

In autonomous vehicles, passengers often recline their seatbacks for a more comfortable posture. Such a reclined posture greatly increases risk of submarining and other injury concerns due to the unfavourable geometrical configuration of occupant, seat and seatbelt. In this paper, numerous simulations with a modified computational dummy model are proposed to analyse effects of various occupant restraint systems in frontal impact, including seatbelt, pretensioner, load limiter, locking tongue, airbag, knee bolster and so on. After the sensitivity analyses, four concepts for designing anti-submarining countermeasures are proposed: (1) increase the lap belt-to-pelvis friction coefficient; (2) reduce the shoulder belt force along with the use of the locking tongue; (3) increase the lap belt angle; (4) reduce the H point forward and downward displacement. Sled tests with anti-submarining countermeasures were conducted to verify the effectiveness of the anti-submarining concepts for reclining seats. Four anti-submarining countermeasures are suggested to prevent the submarining with no other auxiliary hurts: load limiter plus locking tongue, anchor pretensioners plus anti-submarining bar, seat cushion airbag, and retractor plus buckle pretensioner. This paper could give better understanding of submarining mechanism and eligible vehicle design.

Evaluation and characterization of crash-pulses for head-on collisions with varying overlap crash scenarios

Activation time for activating the occupant restraint systems (airbag and seatbelt) is very critical for an optimal safety action. A crash-pulse is the deceleration of the vehicle measured during in a crash. The shape, slope, maximum deceleration and duration of the crash-pulse provides significant information over the nature of occupant motions during in-crash phase and hence the crash severity. The above parameters of the crash-pulse not only depend on the mass and impact velocity but also on the crash configuration (position of impact, overlap, relative approach angle etc.).This study focuses on analysis and characterization of crash-pulses in head-on collision cases with varying overlap configurations. The paper describes causes for occupant injuries during a crash, crash-pulse and its important physical parameters, and different methodologies used to analyse the crash-pulse. Finite element simulation method is used to study the crash-pulses from different crash configurations. A new severity index that has direct influence on the occupant kinematics is defined. The results show that the steep decrease of crash-pulse for small overlap configurations (less than 25 percent of vehicle width) lags by 20 to 25 milliseconds as compared to configurations with large overlaps. The shape of the crash-pulse also changes for crash scenarios with different overlap configurations. The results, discussion and conclusion sections of this paper provide a summary of crash behaviour of varying overlap crash scenarios and insights that can be used for deployment of restraint systems.

Sensitivity Analysis and Interval Multi-Objective Optimization for an Occupant Restraint System Considering Craniocerebral Injury

Abstract In vehicle collision accidents, an occupant restraint system (ORS) is crucial to protect the human body from injury, and it commonly involves a large number of design parameters. However, it is very difficult to quantify the importance of design parameters and determine them in the ORS design process. Therefore, an approach of the combination of the proposed approximate sensitivity analysis (SA) method and the interval multi-objective optimization design is presented to reduce craniocerebral injury and improve ORS protection performance. First, to simulate the vehicle collision process and obtain the craniocerebral injury responses, the integrated finite element model of vehicle-occupant (IFEM-VO) is established by integrating the vehicle, dummy, seatbelt, airbag, etc. Then, the proposed approximate SA method is used to quantify the importance ranking of design parameters and ignore the effects of some nonessential parameters. In the SA process, the Kriging metamodel characterizing the relationships between design parameters and injury responses is fitted to overcome the time-consuming disadvantage of IFEM-VO. Finally, according to the results of SA, considering the influence of uncertainty, an interval multi-objective optimization design is implemented by treating the brain injury criteria (BRIC, BrIC) as the objectives and regarding the head injury criterion (HIC) and the rotational injury criterion (RIC) as the constraints. Comparison of the results before and after optimization indicates that the maximum values of the translational and rotational accelerations are greatly reduced, and the ORS protection performance is significantly improved. This study provides an effective way to improve the protection performance of vehicle ORS under uncertainty.

A two degrees of freedom model–based optimization method for occupant restraint systems in vehicle crash

This paper presents a two degrees of freedom model–based optimization method for occupant restraint systems (ORS), applied before the finite element analysis in a vehicle crash. The method considers the effects of restraint systems (seatbelt, airbag, seat, and knee baffle) on the occupant and establishes the analytical models of them. The method reveals the effect essence of the ORS and takes the occupant response as the target to optimize the restraint system parameters rapidly. The multi-rigid body model of a Toyota Camry vehicle is established to verify the validity and reliability of two degrees of freedom model (TDFM). Comparing the results of the two models, the trends of acceleration-time curves are consistent, and the 85% errors of occupant responses are within 20%. Then, the practicality and effectiveness of the optimization method are confirmed by the instance of Camry ORS. The errors of results solved by optimization and the MADYMO model are all less than 20%. The optimization method can be used to provide an initial parameter range for the finite element simulation to improve the efficiency of the traditional optimization process.

Comparison of wheelchair securement systems designed for use in large accessible transit vehicles (LATVs)

ABSTRACT Design challenges in wheelchair securement for fixed-route, large accessible transit vehicles (LATVs) often create difficulties for passengers who use wheelchairs and operational inefficiencies for public transit agencies. Recent innovations in wheelchair securement technology for LATVs may reduce these challenges. This study explored the usability of three commercially available wheelchair securement systems in a static laboratory environment: a four-point, forward-facing (4P-FF) securement system, a three-point, forward-facing (3P-FF) securement system, and a semi-automated, rear-facing (SA-RF) securement system. Three groups of mobility device users (manual wheelchair users, power wheelchair users, and scooter users) (n = 36) completed wheelchair securement tasks in a full-scale mock-up of an LATV. For the 19 participants who did not use the occupant restraint system (ORS), perceived usability and securement time were compared across the securement systems. Using multiple usability rating scales, most participants reported that each of the systems would be acceptable for regular use. However, the majority indicated an overall preference for the SA-RF, and most rated the SA-RF system as easier, faster, and requiring less assistance to use than the 4P-FF and 3P-FF systems. Alternatives to conventional 4P-FF wheelchair securement in LATVs may thus improve boarding efficiency and transit independence of passengers who use wheelchairs.

A validation sensor based on carbon-fiber-reinforced plastic for early activation of automotive occupant restraint systems

Abstract. In the automotive industry, sensors and sensor systems are one of the most important components in upcoming challenges like highly automated and autonomous driving. Forward-looking sensors (radar, lidar and cameras) have the technical capability to already provide important (pre-)crash information, such as the position of contact, relative crash velocity and overlap (width of contact) before the crash occurs. Future safety systems can improve crash mitigation with sophisticated vehicle safety strategies based on this information. One such strategy is an early activation of restraint systems compared with conventional passive safety systems. These integrated safety systems consist of a combination of predictive forward-looking sensors and occupant restraint systems (airbags, belt tensioners, etc.) to provide the best occupant safety in inevitable crash situations. The activation of the restraint systems is the most critical decision process and requires a very robust validation system to avoid false activation. Hence, the information provided by the forward-looking sensor needs to be highly reliable. A validation sensor is required to check the plausibility of crucial information from forward-looking sensors used in integrated safety systems for safe automated and autonomous driving. This work presents a CFRP-based (carbon-fiber-reinforced plastic) validation sensor working on the principle of change in electrical resistance when a contact occurs. This sensor detects the first contact, gives information on impact position (where the contact occurs) and provides information on the overlap. The aim is to activate the vehicle restraint systems at near T0 (time of first contact). Prototypes of the sensor were manufactured in house and manually and were evaluated. At first, the sensor and its working principle were tested with a pendulum apparatus. In the next stage, the sensor was tested in a real crash test. The comparison of the signals from the CFRP-based sensor with presently used crash sensors in the vehicle highlights its advantages. The crash event can be identified at 0.1 ms after the initial contact. The sensor also provides information on impact position at 1.2 ms and enables a validation of the overlap development. Finally, a possible algorithm for the vehicle safety system using forward-looking sensors with a validation sensor is described.