Showing papers on "Rollover published in 2020"

A Vision-Based Video Crash Detection Framework for Mixed Traffic Flow Environment Considering Low-Visibility Condition

Abstract: In this paper, a vision-based crash detection framework was proposed to quickly detect various crash types in mixed traffic flow environment, considering low-visibility conditions. First, Retinex image enhancement algorithm was introduced to improve the quality of images, collected under low-visibility conditions (e.g., heavy rainy days, foggy days and dark night with poor lights). Then, a Yolo v3 model was trained to detect multiple objects from images, including fallen pedestrians/cyclists, vehicle rollover, moving/stopped vehicles, moving/stopped cyclists/pedestrians, and so on. Then, a set of features were developed from the Yolo outputs, based on which a decision model was trained for crash detection. An experiment was conducted to validate the model framework. The results showed that the proposed framework achieved a high detection rate of 92.5%, with relatively low false alarm rate of 7.5%. There are some useful findings: (1) the proposed model outperformed empirical rule-based detection models; (2) image enhancement method can largely improve crash detection performance under low-visibility conditions; (3) the accuracy of object detection (e.g., bounding box prediction) can impact crash detection performance, especially for minor motor-vehicle crashes. Overall, the proposed framework can be considered as a promising tool for quick crash detection in mixed traffic flow environment under various visibility conditions. Some limitations are also discussed in the paper.

Model predictive rollover prevention for steer-by-wire vehicles with a new rollover index

Abstract: Recent advances in active safety systems provide new opportunities to handle rollover problems more efficiently. This paper presents a Model Predictive Control (MPC) strategy for rollover preventio...

Rollover crashworthiness analyses – an overview and state of the art

Abstract: Rollover crashes are the most severe crash mode among all types of traffic crashes. They consist of sequential complex dynamic events with contributions of the vehicle, human, environmental element...

System reliability as a surrogate measure of safety for horizontal curves: methodology and case studies

Abstract: Reliability analysis has been advocated to account for the uncertainty in geometric design and to evaluate the risk associated with various design options. Most of the previous studies using reliab...

The Influence of Road Geometry on Vehicle Rollover and Skidding.

Abstract: This paper analyzes the influence of single and combined unfavorable road geometry on rollover and skidding risks of D-class mid-sized sport utility vehicles (SUVs) with front-wheel drive for roads with design speeds at 80 km/h. A closed-loop simulation model of human-vehicle-road interactions is established to examine the systematic influence of road geometry on vehicle rollover and skidding. The effects of different road geometry on rollover and skidding on SUVs are studied for pavement surface with good and poor friction when vehicles are in the action of steady state cornering. The rollover and skidding risks of the most unfavorable road segments are assessed. The critical wheel is defined by the threshold of skidding during curve negotiation. The results found that SUVs are not easy to rollover on the most unfavorable roads, regardless of good or poor friction of pavement surface. The safety margin of rollover is greater than that of skidding. The safety margin of skidding is minimal on poor friction roads. Therefore, for the sake of driving safety, it is not recommended to design the roads with these unfavorable road geometry combinations

Rollover prevention and path following control of integrated steering and braking systems

Abstract: In the process of preventing rollover, the expected path of the driver to achieve better anti-rollover effect is often ignored, which may lead to the deviation of vehicle from the original path. Ai...

Non-fragile control design and state estimation for vehicle dynamics subject to input delay and actuator faults

Abstract: In this study, the authors precisely concentrate on the issue of state estimator-based non-fragile reliable control design of the vehicle dynamics in critical situations via the extended dissipative theory. In particular, the vehicle dynamics for rollover mitigation with input time delay and the state estimator are represented by the Takagi–Sugeno (T-S) fuzzy model. Moreover, by constructing a suitable Lyapunov–Krasovskii functional, sufficient conditions for asymptotic stability and extended dissipativity of the proposed T-S fuzzy control system are formulated in terms of linear matrix inequalities (LMIs) such that the estimated state values are exactly synchronised with the actual state values of the considered vehicle model. Also, a non-fragile reliable control design method is then presented via the formulated LMI-based conditions, which can satisfactorily prevent the vehicle rollover in critical situations. Finally, the proposed theoretical results are verified through simulations wherein the significance and importance of the designed non-fragile controller are clearly illustrated.

Advanced study of tire characteristics and their influence on vehicle lateral stability and untripped rollover threshold

Abstract: This paper investigates the effects of tire characteristics on vehicular rollover and lateral stability. Two tire types with different adhesion coefficients were selected to evaluate the relation between vehicular rollover propensity and lateral stability. Simulations were used to calculate the critical rollover factor and to analyze the effects of vehicular parameters on handling, including the center of gravity, payload condition, and vehicle speed, with the two proposed types of tires. To replicate an actual vehicular response, particularly during extreme driving operations, a two-degrees of freedom (DOF) planar two-track model with nonlinear Pacejka’s Magic Tire Formula was applied. Subsequently, a 7-DOF vehicle vibration and roll model was developed to consider the effects of suspension and road excitation. The tire, steering, and vehicle vibration models were implemented in MATLAB/Simulink by subjecting them to the Fishhook maneuver steering input defined by the National Highway Traffic Safety Administration. The results confirm that the adhesion capacities of tires have an opposite effect on lateral vehicle stability and rollover propensity, while both suspension parameters and road excitation inputs significantly influence vehicle rollover and lateral stability. Additionally, we identified a positive correlation between vehicle properties and lateral handling, especially when tire characteristics are considered.

A Comprehensive Analysis for the Heterogeneous Effects on Driver Injury Severity in Single-Vehicle Passenger Car and SUV Rollover Crashes

Abstract: In road traffic crashes, although rollover crashes account for a relatively low proportion, those result in a high fatality rate. The present study performed random parameters ordered logit models to examine risk factors as well as their heterogeneous effects on driver injury severity in single-vehicle passenger car and SUV rollover crashes. Crash data for the empirical analysis were extracted from Texas Crash Record Information System (CRIS) database during the year 2016. Model estimation results show that six variables (male drivers, drivers’ age, airbag deployment, failure to drive in single lane, speed limit, and rural area) were found to produce normally distributed parameters in passenger car model, while nine parameters (male drivers, safety belt use, airbag deployment, drug or alcohol use, failure to drive in single lane, improper evasive action, vehicle model year, friday, and rural area) in SUV model were found to be normally distributed. Several other factors with fixed parameters were found to be associated with driver injury severity in single-vehicle passenger car or SUV rollover crashes, most notably: ejection or partial ejection, turning left, intersection, August, adverse weather conditions, and night with light. These variables were significant in both models; most variables have stronger effects on nonincapacitating injury and serious injury outcomes in SUV than in passenger car rollover crashes. These findings provide a deep insight into causality nature and factor involved in driver injury severity in single-vehicle passenger car and SUV rollover crashes and are also helpful for transport agencies to determine appropriate countermeasures aimed at mitigating injuries sustained by drivers in single-vehicle rollover crashes.

Research on Active Obstacle Avoidance Control Strategy for Intelligent Vehicle Based on Active Safety Collaborative Control

Abstract: Aiming at the issue of active obstacle avoidance control for intelligent vehicles under emergency, an active safety collaborative control system integrated with adaptive cruise control (ACC), rear steering control (RSC), and rollover braking control (RBC) is developed. The proposed novel control architecture consists of a supervisor, an upper controller, and a lower controller. The supervisor decides which control mode to be used based on multi-sensors information of the driving vehicle. Active rear wheel steering based on lateral acceleration feedback and active braking control strategies based on fuzzy PID are added into the control model to enhance driving stability. To make the vehicle motion control model suitable for highway path tracking with obstacle avoidance under emergency, a priority is given to the RBC controller even though the vehicle speed is lower than the expected speed when the rollover index exceeds the safety threshold. A nonlinear vehicle simulation model is established to validate the proposed control scheme based on Carsim. Finally, a Carsim-Simulink co-simulation model is constructed, and simulation results show that the proposed integrated control strategy based on active safety collaborative control has good performance in both path tracking and driving stability, and has better stability of rollover under emergency.

Tractor Rollover Protection: Is the Incorrect Use of Foldable Rollover Protective Structures Due to Human or to Technical Issues?:

Abstract: Objective:To identify the critical behaviors that may hinder the correct use of foldable rollover protective structures (FROPS) on tractors and to explore the influence of user factors and FROPS te...

Study on the Influence of Road Geometry on Vehicle Lateral Instability

Abstract: According to the accident analysis of vehicles in the curve, the skidding, rollover, and lateral drift of vehicles are determined as means to evaluate the lateral stability of vehicles. The utility truck of rear-wheel drive (RWD) is researched, which is high accident rate. Human-vehicle-road simulation models are established by CarSim. Through the orthogonal experiment method, the effects of different road geometries, speed, and interaction factors between road geometries on vehicle lateral stability are studied. In this paper, skidding risk of the vehicle is characterized by the Side-way Force Coefficient (SFC). Rollover risk of the vehicle is characterized by lateral acceleration and the load transfer ratio. Lateral drift risk of the vehicle is characterized by the sideslip angle of wheels. The results of orthogonal analysis reveal that the maximum tire-road friction coefficient and speed are highly significant in skidding of the vehicle. The effects of the combination of horizontal alignment and superelevation on vehicle skidding are important. The effects of horizontal alignment and speed on vehicle rollover risk are highly significant. The effects of superelevation on vehicle rollover risk are significant. The effects of the interaction of horizontal alignment and superelevation are also important on vehicles’ rollover risk. The speed and the maximum tire-road friction coefficient have highly significant effect on the vehicle’s lateral drift. The superelevation has a significant effect on the vehicle’s lateral drift. The effects of the interaction of horizontal alignment and superelevation and longitudinal slope are also important on the lateral drift of the vehicle.

Multi-objective Collaborative Optimization for the Lightweight Design of an Electric Bus Body Frame

Abstract: To analyze the rollover safety, finite element models were established for the electric bus body frame, rollover simulation platform, living space, and bus rollover. The strength and stiffness of the body frame were calculated under four typical working conditions considering the main low-order elastic modal characteristics. The results indicate that the initial body frame of the electric bus satisfies the required structural strength, stiffness, modes, and rollover safety, and it has great potential for lightweight design. Sensitivity and structural contribution analyses were performed to determine the design variables for lightweight optimization of the body frame, and a mathematical model was established for multi-objective collaborative optimization design of the electric bus. Then, the radial basis function neural network was used to approximate the optimization model. Besides, the accuracy of the approximate model was verified, and the non-dominated sorting genetic algorithm II was employed to determine solutions for the lightweight optimization. Compared with the initial model, the mass of the optimized model is reduced by 240 kg (9.0%) without any changes in the materials of the body frame.

Research on a Novel Vehicle Rollover Risk Warning Algorithm Based on Support Vector Machine Model

Abstract: A novel vehicle rollover warning algorithm based on support vector machine (SVM) empirical model is proposed to improve the real-time of un-tripped rollover warning algorithm and accuracy of dynamic rollover warning. Considering the nonlinear characteristic of driver-vehicle-road interaction and the uncertainty of modeling, the traditional deterministic methods cannot meet the requirements of accurate vehicle rollover warning modeling. The probability method considering issues of uncertainty is applied to design vehicle dynamic rollover warning algorithm. The SVM empirical model considers the uncertainties of the driver-vehicle-road system and the real variability of the parameters, provides an explicit function of vehicle rollover safety limit and its gradient, and utilizes the hypersurface visualization boundary to define the rollover safety area and the unsafe area. Targeting on sport utility vehicle under the condition of high-speed emergency obstacle avoidance, simulations are carried out to verify the proposed vehicle rollover warning algorithm based on SVM empirical model and of the simulation results show that the proposed algorithm has accurate warning and good real-time performance. It can effectively improve the warning accuracy of vehicle dynamic rollover, reduce the interference of nonlinear and uncertainty, and significantly improve the active safety performance with vehicle rollover prevention.

Optimisation of Bus Superstructure for Rollover Safety According to ECE-R66

Abstract: A bus rollover is one of the most severe accidents that usually causes a large number of fatalities and injured occupants. This paper aims to investigate the key parameters affecting the damage and deformation behaviours of bus superstructure under rollover test according to Economic Commission for Europe Regulation 66 (ECE R66) as well as to design an economical lightweight bus structure by using response surface optimisation technique. The rollover simulations are performed by means of explicit dynamic analysis via Radioss finite element programme and validated by experimental data. Factorial design is implemented to pinpoint significance of each structural component based on its energy absorption under rollover condition. The significant parameters for rollover safety are found to be the stiffness of roof, pillar, and floor structures, respectively. Crashworthiness Index (CI) is proposed as an evaluation factor of overall rollover strength of bus structure. A ratio of CI to mass is proposed as an improvement criterion to supervise the progressive path of steepest descent and used to control the degree of improvement. Successive response surface optimisation via central composite design and composite desirability are employed to resolve the optimum lightweight bus structure passing ECE R66 requirements.

Numerical assessment of occupant responses during the bus rollover test: A finite element parametric study:

Abstract: Rollover crashes of buses are usually associated with multiple impacts that can result in complex interactions between passengers and a bus superstructure. Although there have been a few field data...

Dynamic Rollover Prediction of Heavy Vehicles Considering Critical Frequency

Abstract: Rollover of commercial heavy vehicles can cause enormous economic losses and fatalities. It is easier for such vehicles to rollover if the driver’s steering frequency is close to the critical frequency of the vehicle’s roll motion; however, the critical roll frequency has rarely been investigated. In this study, the second-order transfer function between the steering input and roll angle was developed to calculate the critical frequency of the vehicle’s roll motion. The simulated spectrum and transfer function were then used to dynamically predict the peak lateral load transfer ratio. Laboratory experiments were conducted using a scaled vehicle to verify the critical roll frequency. The results suggest that the peak value of the lateral load transfer ratio during steering can be accurately determined from the driver’s input, and the critical roll frequency has a dominant effect on the dynamic rollover of heavy vehicles.

A novel data-driven rollover risk assessment for articulated steering vehicles using RNN

Abstract: Articulated steering vehicles have outstanding capability operating but suffer from frequent rollover accidents due to their complicated structure. It is necessary to accurately detect their rollover risk for drivers to take action in time. Their variable structure and the variable center of mass exhibit nonlinear time-variant behavior and increase the difficulty of dynamic modelling and lateral stability description. This paper proposes a novel data-driven modelling methodology for lateral stability description of articulated steering vehicles. The running data is first collected based on the typical operations that prone to rollover and then classified into two types: Safety and danger. The data quality is further improved by wavelet transformation. Finally, an RNN model is built on the data. The experimental results show that the output of the RNN model can accurately quantify lateral stability of the vehicle, i.e., the risk of rollover, when it is turning and crossing uneven surfaces or obstacles.

Determining the Vertical Force When Steering

Abstract: When the vehicles move at high velocity and quickly steer, the vehicles can be rollover. The first sign of this phenomenon is that two wheels on the same side are completely separated from the road surface. The typical value for this sign is the vertical force FZ at each wheel. If this value gradually decreases to zero, the wheel runs the risk of separating from the road surface that may lead to rollover. Therefore, the value of the vertical force Fz in different conditions needs to be determined to detect the imminent limit of the rollover phenomenon. This research established the spatial dynamic model of the vehicle to determine the vertical force FZ based on the simulation method. Besides, the equation describing the relationship between vertical force FZ, velocity v, and acceleration steering e corresponding to the value of steering angle d is also established by the calculation process. From this equation, the value of the vertical force FZ can be simply calculated with relatively high accuracy based on determining conditions. The results of this research are the basis for determining and establishing the vehicle's rollover limit.

Numerical Low-Back Booster Analysis in a 6-Year-Old Infant during a Dolly Rollover Test

Abstract: This paper analyzes the possible head and chest injuries, produced in a Hybrid III dummy model of a six-year-old child during a rollover test, while the child uses a passive safety system low-back booster (LBB). Vehicle seats and passive safety systems were modeled with a CAD (Computer Aided Design) software; later, all elements were analyzed using the finite element method (FEM) with LS-DYNA® software. The border conditions were established for each study, in accordance with the regulations of Federal Motor Vehicle Safety Standards (FMVSS), and following the FMVSS 213 standard for the mounting and fastening of the infant, the FMVSS 208 for the dolly methodology test with the vehicle rollover was performed, implementing such analysis under the same conditions for a vehicle Toyota Yaris 2010. The numerical simulations were performed during an interval of 1 second, obtaining data values for periods of 2 milliseconds. This paper examines the efficiency of the system; three case studies were carried out: Study I: vehicle seat belt (VSB); Study II: the LBB system was secured by the seat belt; Study III: the LBB system with ISOFIX anchorage. The values of decelerations for the head and thorax of the infant were obtained, as well as neck flexion and thoracic deflection. The main factor to reduce injuries during a rollover accident is the correct anchorage of the LBB, and this is achieved with the ISOFIX system, since it prevents the independent movement of the LBB, unlike when it is fastened with the seat belt of the vehicle. The results show low levels of head and chest injury when ISOFIX is used because of reduced thoracic deflection during infant retention.

Active steering control for vehicle rollover risk reduction based on slip angle estimation

Abstract: In this study, a robust controller is proposed for rollover risk suppression in automatically-driven vehicles by reducing the lateral acceleration through a steer-by-wire system equipped on the vehicles. First, since the slip angle is difficult to measure directly, a sliding mode observer combining an add-on switching term with a linear observer is developed to provide more robust estimation of slip angle in the presence of system uncertainties. Second, an adaptive sliding mode control method is proposed, in which the control gain is adaptively tuned to compensate for the system uncertainties. Lastly, simulation is conducted and the results verify that the proposed estimator and controller can reduce the vehicle rollover risk efficiently and robustly.

A comprehensive assessment of bus rollover crashes: integration of multibody dynamic and finite element simulation methods

Abstract: Rollover crashes have the highest fatality rate and exhibit complex and unpredictable mechanisms in terms of vehicle-ground and vehicle-occupant interactions. The objective of this study is to eval...

Morphometry as a Key to Investigate the Stability to a Wind-Induced Rollover of Agricultural Equipment for Irrigation

Abstract: Received: 29 July 2019 Accepted: 28 November 2019 A problem that is common in agriculture but not very publicized, thanks to the absence of victims, is the rollover of Centre Pivot and Lateral Move irrigation systems. These accidents are due to particularly-strong winds acting on the spans, and they are potentially very destructive for the installations. Also, the restoration phase of the installations requires always an intervention of lifting of the machinery on the field, with a potential further damage to crops (setting) and land (compaction). Given the basic inevitability of the phenomenon, due to atmospheric events, these rollovers could be however limited e.g. by proposing a system design granting a higher stability. Therefore, we have firstly modelled the rollover dynamics of these systems, considering the geometry, the masses, the forces acting on them (wind, gravity), the position of the centre of gravity. Then, thanks to morphometry, we have investigated booms’ stability as a consequence of a proportional or not-proportional alteration of the system sizes, in particular: the upscaling of supports, done by some manufacturers, and the lengthening of spans, often required by customers. Morphometry is a method born in biology, typically used to describe and analyse statistically the shape variations within and among samples of organisms as a result of growth, experimental treatments or evolution. As the idea of evolutionary adaptation is intrinsic in the technical evolution of human-made systems (models, variants) operated by manufacturers, also artificial systems can be studied or improved via the morphometry, as operated here. The output of this study is a physical model of rollover and a sensitivity analysis of a reference configuration for an irrigation boom. Thanks to these analyses, we were able to demonstrate, for example, how a scaling-up of boom supports, respectful of geometric ratios, can increase the system stability despite the elevation of the pressure point of the wind on the frame.

State observation of nonlinear off-road vehicle system under complex maneuver condition

Abstract: The information of vehicle attitude and tire force under complex environment and maneuver condition is of great significance for system risk prediction and active control system intervention. In order to collect the accurate system states, the coupling vehicle dynamics model and moving horizon estimation method are employed to solve the online optimization problem based on the premise of rolling optimization. Furthermore, the accurate observation and acquisition of the vehicle system state are realized. On this basis, the simulation process of the vehicle state observation using moving horizon estimation method and unscented Kalman filter algorithm are implemented, respectively. The corresponding observation results under complex maneuvering conditions are further validated by using the hardware-in-the-loop experimental platform. Finally, the comparison of the observation results obtained by the unscented Kalman filter and moving horizon estimation algorithms demonstrate that the moving horizon estimation method can effectively improve the observation accuracy of vehicle system state in complex environment, including vehicle roll angle and tire dynamic force. The results obtained through moving horizon estimation method are conducive to the further signal early warning, risk prediction and assessment, as well as systematic intervention and active rollover control.