International Journal of Vehicle Safety (5 papers in press)
Based on tiredness index of the driver, to evaluate a forward collision probability index
by Yuan-Lin Chen
Abstract: This paper presents a forward collision probability evaluation based on the tiredness index of a driver for alerting and assisting the driver to avoid the forward collision in highway driving. From an electroencephalograph (EEG), we can figure out the relaxed index (RI) and focus index (FI) of the driver. Then a tiredness index (TI) of the driver will be found. We use the tiredness index, the time-to-collision (TTC) and headway time (HT) to be the factors for evaluating the forward collision probability. When we evaluate the forward collision probability indices of TTC and HT, a Mamdani fuzzy inference algorithm is presented for calculating the forward collision probability index (FCPI) of the vehicle. The FCPI is easily understood for the driver, even those who do not have any professional knowledge in the vehicle field. At the same time, the behaviour of the driver is taken into account, called the self-learning algorithm, for each driver. For the FCPI, the value 0 indicates the 0% probability of forward collision, and the values 0.5 and 1 indicate the 50% and 100% probabilities of forward collision, respectively. The presented probability index of forwarding collision is useful and easily understood for alerting the driver to avoid the forward collision when driving on the highway.
Keywords: EEG; tiredness index; forward collision probability index.
Path tracking control for inverse vehicle handling dynamics
by Yingjie Liu, Dawei Cui
Abstract: A path planning problem for inverse vehicle handling dynamics is considered. The objective is to devise a path tracking controller under the condition that a vehicle travels along a prescribed path to generate an expected trajectory. Aiming at this purpose, a tyre model and optimal preview time are established first. Then a path tracking controller based on linear quadratic regulator (LQR) method is designed, and calculation for the path tracking problem is simulated with a joint simulation of Carsim/Simulink. Finally, a real vehicle test is executed to verify the rationality of the path tracking controller. The results show that the minimum lateral position error between the generated trajectory and the prescribed path can be a good indicator of successful solving of the path tracking problem in inverse vehicle handling dynamics for the LQR method. The study can help drivers easily identify safe lane-keeping trajectories and area.
Keywords: vehicle handling dynamics; path tracking; linear quadratic regulator; inverse problem.
A simulation-based comparative study on lateral characteristics of trucks with double and triple trailers
by Yang Chen, Andrew Peterson, Ce Zhang, Mehdi Ahmadian
Abstract: This paper investigates the lateral stability and manoeuvrability in long combination vehicles (LCVs), namely semi-trucks with 28-ft doubles, 28-ft triples, and 33-ft doubles, using TruckSim. In recent years, due to the rapid increase of E-commerce cargo transport demands, trucks with multiple trailers have been used with increasing frequency on US highways. The most common configuration is 28-ft doubles, although in some states, 28-ft triples and longer doubles, such as 33-ft trailers, are also allowed. LCVs provide operational advantages in terms of loading and unloading, ease of distribution, and other key logistics that are superior to the conventional 53-ft trailers that are commonly used for bulk cargo over long hauls. The vast proliferation of LCVs on US highways heightens awareness of their dynamics, including lateral stability and maneuverability which are strongly tied to highway safety. This study provides a comparative evaluation of the lateral characteristics for tractors with 28-ft double, 28-ft triple, and 33-ft double trailers. In particular, the likelihood of rollovers, rearward amplification, and off-tracking are analysed among those LCVs using the multi-domain dynamic models developed in TruckSim. The efforts to validate the truck dynamic model against test results are also included. The simulation results show that trucks with triple trailers exhibit a larger rearward amplification, higher likelihood of rollovers, and larger off-tracking than trucks with double trailers. Additionally, the results indicate that increasing the trailer length from 28 to 33 feet does not increase the likelihood of rollovers or the rearward amplification. In fact, the longer trailers provide a slight amount of additional roll stability due to their longer wheelbase.
Keywords: lateral stability; off-tracking; rearward amplification; rollover; long combination vehicles; 33-ft doubles; TruckSim.
Far-side occupant responses based on current US side-impact protocol using finite element human body model
by Syed Imam
Abstract: Most of the applied vehicle side impact occupant protection research to date has concentrated on near-side occupants. Currently, no regulation exists in North America for the far-side occupant protection. Real world crash data has shown that occupants seated on the non-struck side, defined as far-side occupants, are still subjected to a risk of injuries. The objective of this study is to investigate body responses for the far-side occupant using current US side impact protocols. Current side impact protocol in US is designed to meet side moving deformable barrier (MDB) and fixed oblique pole impact. Lateral Impact New Car Assessment Program (LINCAP) and Insurance Institute for Highway Safety (IIHS) barriers are used as bullet vehicle to assess the occupant performances in the side impact. Two seating cases are addressed: the first case consists of a far-side occupant in the first row (single occupant) to evaluate the interaction of the occupant to the structure, while the second case, a near-side occupant, was added to the far-side occupant (two occupants in a row) to study the interaction of the occupant-to-occupant. A finite element human body model (50th male) was used as a far-side and near-side occupants. Simulation results indicated that the LINCAP barrier can potentially produce significant head rotational acceleration and thoracic rib deflection if far-side occupant is included in the existing near-side crash protocols.
Keywords: far-side; near-side; human body model; side impact; GHBM; crashworthiness; far-side occupant.
Accelerating behaviour of the driver and acceleration characteristics of the dangerous event
by Rui Liu, Xichan Zhu, Lin Liu, Biao Wu
Abstract: The accelerating behaviour of the driver and the relationship between the extreme acceleration and dangerous event are studied by using the naturalistic driving data, i.e. China-FOT. Firstly, the bivariate distributions between the longitudinal acceleration, lateral acceleration and velocity are proposed. The bivariate distribution between the accelerations presents the dual triangle distribution pattern, whereas the bivariate distribution between the acceleration and velocity presents piecewise distribution pattern. Next, the univariate distributions of lateral acceleration and longitudinal acceleration are achieved. It is found that the accelerations approximately follow Pareto distribution, which is known as the heavy tail distribution. The heavy tail distribution reveals that the frequency of high acceleration is much larger than that of the Normal distribution. The extreme driving data in 0.01st density contour outer area are analysed. The results show that most of the extreme acceleration data are not dangerous events. The majority of the dangerous events are in the high braking deceleration region (>4m/s2), whereas high lateral acceleration does not have apparent relationship with dangerous events. In the last, it is shown that travel distance or travel time does not have significant influence on the number of events. Driving style is the main factor that accounts for the difference in the number of events. The drivers can be divided into two categories according to the number of events, i.e. aggressive driver and normal driver. Aggressive driver tends to drive the vehicle in intense way, and they are much more likely to be involved in dangerous events.
Keywords: naturalistic driving studies; accelerating behaviour; dangerous event; driving style.