Rollover Risk Of Vehicles Research Articles

Evaluation of SSF, Roof Crush Test as an Alternative to Dynamic Rollover Test using Numerical Approach

Rollover accidents are classified into various scenarios, and with the increasing prevalence of high-centre-of-gravity (CG) vehicles in Southeast Asia (SEA) particularly in Malaysia, such as SUVs, MPVs and pickup trucks; assessing vehicle rollover risk has become critical. Even though rollover incident recorded low number of cases compared to other crash types in Malaysia, it had the highest casualty index for killed or seriously injured (KSI) and the situation induces worries because majority of the fatalities in rollover crashes among passenger vehicle occupants goes to high CG vehicle type. There are several limitations from the SEA nations to enforce costly dynamic rollover test as safety specification for SEA market requirement. Therefore, this study aims to evaluate Static Stability Factor (SSF), and roof resistance test (FMVSS 216), as an alternative to the dolly rollover test (FMVSS 208) using Finite Element Analysis (FEA). A correlated Chevrolet Silverado MY 2014 model is employed, with different SSF values representing varying levels of vehicle stability. The study evaluates peak force, peak energy absorption, and maximum intrusion during rollover simulations according to FMVSS 208 for vehicle models with different SSF values. Results indicated that vehicles with lower SSF values lead to higher energy absorption and intrusion, signifying increased rollover impact. Additionally, the article suggests that FMVSS 216 Roof Resistance Test is more severe than FMVSS 208 and vehicle rating system based on SSF value is vital for market awareness. Understanding the vehicle structural integration in rollover scenarios is essential for improving safety measures and vehicle design, especially for high-centre-of-gravity vehicles prevalent in the market.

Rollover Prevention and Motion Planning for an Intelligent Heavy Truck

It is very necessary for an intelligent heavy truck to have the ability to prevent rollover independently. However, it was rarely considered in intelligent vehicle motion planning. To improve rollover stability, a motion planning strategy with autonomous anti rollover ability for an intelligent heavy truck is put forward in this paper. Considering the influence of unsprung mass in the front axle and the rear axle and the body roll stiffness on vehicle rollover stability, a rollover dynamics model is built for the intelligent heavy truck. From the model, a novel rollover index is derived to evaluate vehicle rollover risk accurately, and a model predictive control algorithm is applicated to design the motion planning strategy for the intelligent heavy truck, which integrates the vehicle rollover stability, the artificial potential field for the obstacle avoidance, the path tracking and vehicle dynamics constrains. Then, the optimal path is obtained to meet the requirements that the intelligent heavy truck can avoid obstacles and drive stably without rollover. In addition, three typical scenarios are designed to numerically simulate the dynamic performance of the intelligent heavy truck. The results show that the proposed motion planning strategy can avoid collisions and improve vehicle rollover stability effectively even under the worst driving scenarios.

Rollover Risk Probability Analysis for SUVs and MPVs in the ASEAN Market


 
 
 The number of single vehicle and rollover accidents in Indonesia has reached approximately 10,000 (7%) per year. Such an accident is typically followed by a large number of fatality, especially in the case for SUVs and MPVs. In the US, motor vehicle rollovers involving passenger cars, pickup trucks, and sport utility vehicles result in around 10,000 deaths and 27,000 serious injuries each year. Although single vehicle and rollover accident in Indonesia accounts for less than 10% tow- away crashes involving light vehicles, it has recorded almost one-third of light-vehicle occupant fatalities. The aim of this research is to develop a method to predict rollover probability. One of the key geometrical parameters to describe the rollover risk of vehicles is Static Stability Factor (SSF) which can be correlated with rollover probability using NHTSA statistical data. SSF is defined as the vehicle half-track width divided by its center of gravity height. Since information pertaining to the location of centre of gravity is not publicly available, a method was developed to predict it by using published technical data which were validated using NHTSA database. It was then used to predict rollover probability data for MPVs and SUVs in Indonesia. The method can be a tool for manufacturers, consumers, and regulators to reduce the number of rollover accidents which in turn may reduce occupant fatalities. The result can also be a means to assess the trend of rollover accident risk in the ASEAN region and will be beneficial for ASEAN NCAP in determining SUVs and MPVs safety rating.
 
 

Study on the Influence of Road Geometry on Vehicle Lateral Instability

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.

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

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.

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

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.

Study on Rollover Index and Stability for a Triaxle Bus

Vehicle rollover, and its resulting fatalities, is an actively researched topic especially for multi-axle vehicles in the field of vehicle dynamics and control. This paper first presents a new rollover index for a triaxle bus to accurately evaluate its rollover possibility and then discusses the influence laws of the vehicle rollover dynamics to explore the mechanism of its stability. First, a six degree of freedom rollover model of the triaxle bus is developed, including lateral, yaw, roll motion of the sprung mass of the front/rear axle, and roll motion of the unsprung mass of the front/rear axle. Next, some key parameters of the vehicle rollover model are identified. A new rollover index is deduced according to the basics of vehicle dynamics, to predict vehicle rollover risk for the triaxle bus, which is verified by TruckSim. Furthermore, the influence laws of vehicle rollover dynamics by vehicle parameters and road parameters are discussed based on the simulation results. More importantly, the results show that the new method of modeling can precisely describe the rollover dynamics of the studied bus, and the proposed new index can effectively evaluate the rollover possibility. Therefore, this study provides a theoretical basis to improve anti-rollover ability for triaxle buses.

H∞/LPV controller design for an active anti-roll bar system of heavy vehicles using parameter dependent weighting functions

Vehicle rollover is a very serious problem when considering the safety of heavy vehicles, which can result in large financial and environmental consequences. This paper investigates the interest of a Linear Parameter Varying (LPV) controller for an active anti-roll bar system of single unit heavy vehicles, in order to enhance roll stability. We propose a parameter dependent H∞/LPV controller with weighting functions, scheduled by the forward velocity (the varying parameter of the vehicle LPV model) and by the normalized load transfers at the two axles (part of the parameter dependent weighting functions) providing an on-line performance adaptation to the vehicle rollover risk. The effectiveness of the proposed controller is validated by using the TruckSim® simulation software with two different types of heavy vehicle: a fully loaded bus and a truck. The simulation results, in the frequency and time domains, show that the proposed strategy drastically improves the vehicle roll stability when compared with a H∞/LTI controller, a fixed weighting functions H∞/LPV controller and a passive anti-roll bar system.

Stability and optimised H∞ control of tripped and untripped vehicle rollover

ABSTRACTVehicle rollover is a serious traffic accident. In order to accurately evaluate the possibility of untripped and some special tripped vehicle rollovers, and to prevent vehicle rollover under unpredictable variations of parameters and harsh driving conditions, a new rollover index and an anti-roll control strategy are proposed in this paper. Taking deflections of steering and suspension induced by the roll at the axles into consideration, a six degrees of freedom dynamic model is established, including lateral, yaw, roll, and vertical motions of sprung and unsprung masses. From the vehicle dynamics theory, a new rollover index is developed to predict vehicle rollover risk under both untripped and special tripped situations. This new rollover index is validated by Carsim simulations. In addition, an H-infinity controller with electro hydraulic brake system is optimised by genetic algorithm to improve the anti-rollover performance of the vehicle. The stability and robustness of the active rollover prevention control system are analysed by some numerical simulations. The results show that the control system can improve the critical speed of vehicle rollover obviously, and has a good robustness for variations in the number of passengers and longitude position of the centre of gravity.

Analysis of the torsional rigidity of a dump semi-trailer under unfavourable load conditions

The tipping operation of a dump semi-trailer increases the vehicle rollover risk. A higher centre of gravity, a transversal slope, varying compression degrees of the ground or an irregular unloading can lead to non-desirable lateral instability situations. Therefore it is interesting to analyse the torsional rigidity of the semi-trailer dump bed under unfavourable load conditions generating torsional compliance. By means of detailed finite element models, it has been possible to verify the correct performance of the articulated coupling between the semi-trailer dump bed and the hydraulic actuator in the presence of any unfavourable stability conditions that could occur.

Vehicle rollover risk and electronic stability control systems

Background:Electronic stability control (ESC) systems were developed to reduce motor vehicle collisions (MVCs) caused by loss of control. Introduced in Europe in 1995 and in the USA in 1996, ESC...