Car Deceleration Research Articles

A NEW WAY TO CONTROL THE DISTRIBUTION OF BRAKING FORCES BETWEEN THE AXLES OF THE CAR

The distribution of braking forces between the axles has a significant impact on the stability of the car when braking. Over the years, dozens of authors have proposed various methods for regulating braking forces and devices for their implementation (brake force regulators - RTS). The regulation process in most of the known technical solutions was carried out by changing the ratio of the pressure of the working fluid (liquid or air) in the actuators of the brake drive of the front and rear brakes. To change the ratio of the specified pressure, the regulation of the working fluid was used, which led to the instability of the regulation characteristics and the failure of the brake system. In this article, a new method for controlling the distribution of braking forces between the axles is proposed and researched, the essence of which is to change the ratio of the total areas of the actuators of the brake drives (the areas of the pistons of the working brake cylinders). The implementation of this method of controlling the distribution of braking forces between the axles became possible due to the creation of open-type multi-piston disc brakes with two pairs of concentrically arranged brake pads. The proposed method makes it possible to increase the stability of the car not only during emergency, but also during service braking. The aim of the study is to increase the stability of the car during emergency and service braking by using a new method of controlling the distribution of braking forces between the axles by discretely changing the size of the active working areas of the working brake cylinders. To achieve this goal, the tasks of determining the value of the coefficient of distribution of the brake force on the front axle of the car with a different combination of the included working brake cylinders on the wheels and rear wheels and determining the threshold values of the car deceleration, at which it is necessary to change the ratio of the included working brake cylinders on the wheels of the front and rear axles, are solved .The results of the study showed that the use of multi-piston disc brakes on the front and rear wheels of a twoaxle vehicle makes it possible to organize the process of impulse control of the distribution of braking forces between the axles.

The implications of situation and route familiarity for driver-pedestrian interaction at uncontrolled mid-block crosswalks

Most routine daily trips take place along the same route, a fact that previous studies have not investigated together with the repeated situation of conflicting with other road users. Consequently, our study addresses driver behaviour by separating the driving experience into three categories: (i) drivers unfamiliar with the route, (ii) those route-familiar, and (iii) situation-familiar drivers. The specific case of driver-pedestrian interaction at uncontrolled mid-block crosswalks is investigated. A multi-level factorial experiment including (i) crosswalk design (linear sidewalk and curb extension), (ii) driver familiarity, and (iii) pedestrian time gap acceptance (4, 6, and 8 s) was conducted using a driving simulator. Fifty-two participants were divided into four groups and stratified by age, gender, and driving experience. The minimum instantaneous time to collision, post-encroachment time, maximum car deceleration, and maximum car speed were all used as surrogate safety measures (SSM).Route-familiarity led to higher speed, while situation-familiarity positively affected driving behaviour making drivers more inclined to decrease their speed at circa 100 m before a crosswalk. The curb extension layout enhanced pedestrian safety and mitigated any adverse effects due to familiarity, with a particularly relevant impact on SSM at low accepted time gaps for pedestrians. Situation- and route-familiarity treatment protocols lead to different behaviours among drivers, indicating a clear need to account for these two familiarity levels in experiments on safety-related countermeasures.

To the question of action on the rods lying on elastic foundation, inertial load with a variable speed of its movement

A method for calculating the rods on elastic foundation under the inertial load action when it moves at a variable speed is proposed. Test problems about a force or load movement with variable speeds along a hinged beam and about the movement with a high-speed railway car deceleration along a track section modeled by a hinged supported beam of great length on an elastic foundation are considered. The selection of the elastic foundation material of the rail track determines the dynamics of the high-speed railway car in different modes of its movement. To construct the methodology, the previously proposed by the author of the article solutions are used: a step-by-step procedure for solving the problems of unsteady dynamics of structures and the method of “nodal accelerations” to take into account the action on structures of a moving inertial load.

Analysis of car driver responses to avoid car-to-cyclist perpendicular collisions based on drive recorder data and driving simulator experiments

The reduction of cyclist injuries and fatalities is one of the important issues in traffic safety. To establish countermeasures to avoid collisions, it is necessary to understand driver’s responses in such critical situations. From videos of drive recorders, the behavior of cyclists and drivers that led to car-to-cyclist collisions can be analyzed objectively. In this research, the drivers’ responses to avoid car-to-cyclist perpendicular collisions were examined using videos of drive recorders, and through using a driving simulator.First, drivers’ responses to avoid collisions were compared between near-miss incidents and actual collisions using videos from drive recorders. In a statistical analysis of selected parameters of the drivers’ responses, the average values of different parameters such as the time-to-collision (TTC), the deceleration at the time the cyclist was first visible to the driver, and the braking reaction time (BRT) were significantly different between near-miss incidents and collisions. Applying logistic regression to the near-miss and collision data revealed that the BRT at the time the cyclist was first visible had the largest influence on collision occurrences. The velocity-TTC, and the velocity-distance graphs at the time of braking-onset was plotted; the car deceleration of 5.2 m/s2 was the threshold which discriminated near-miss and collisions.Second, the responses of people to avoid collisions against cyclists were investigated in a driving simulator. Based on real-world collision videos from the drive recorders, two scenarios were reconstructed where the crossing cyclist appeared suddenly from behind view-blocking obstructions at an intersection. Scenario A has a relatively large TTC of 1.9 s, and scenario B had a small TTC of 0.5 s. The BRT was significantly smaller in the group that avoided collisions than in the group that collisions occurred in scenario A, whereas all parameters (TTC, BRT, and car deceleration) were all significantly smaller in the group that avoided collision in scenario B.The driver response parameters (TTC, BRT and car deceleration) were comparable between the drive recorder data and the driving simulator experiments. It was demonstrated that the BRT is the most important parameter toward avoiding collisions. Some drivers who accelerated the cars at the intersections had large BRT, and this led to collisions. Additionally, it was observed that swerving of cars without braking was not effective for collision avoidance.

Оценка свойств замедления автомобиля при использовании зимнего типа шин на укатанном снежном покрытии

Оценка свойств замедления автомобиля при использовании зимнего типа шин на укатанном снежном покрытии

Application of energy derivative method to determine the structural components' contribution to deceleration in crashes

ABSTRACTObjective: For occupant protection, it is important to understand how a car's deceleration time history in crashes can be designed using efficient of energy absorption by a car body's structure. In a previous paper, the authors proposed an energy derivative method to determine each structural component's contribution to the longitudinal deceleration of a car passenger compartment in crashes. In this study, this method was extended to 2 dimensions in order to analyze various crash test conditions. The contribution of each structure estimated from the energy derivative method was compared to that from a conventional finite element (FE) analysis method using cross-sectional forces.Method: A 2-dimensional energy derivative method was established. A simple FE model with a structural column connected to a rigid body was used to confirm the validity of this method and to compare with the result of cross-sectional forces determined using conventional analysis. Applying this method to a full-width frontal impact simulation of a car FE model, the contribution and the cross-sectional forces of the front rails were compared. In addition, this method was applied to a pedestrian headform FE simulation in order to determine the influence of the structural and inertia forces of the hood structures on the deceleration of the headform undergoing planar motion.Result: In an oblique impact of the simple column and rigid body model, the sum of the contributions of each part agrees with the rigid body deceleration, which indicates the validity of the 2-dimensional energy derivative method. Using the energy derivative method, it was observed that each part of the column contributes to the deceleration of the rigid body by collapsing in the sequence from front to rear, whereas the cross-sectional force at the rear of the column cannot detect the continuous collapse. In the full-width impact of a car, the contributions of the front rails estimated in the energy derivative method was smaller than that using the cross-sectional forces at the rear end of the front rails due to the deformation of the passenger compartment. For a pedestrian headform impact, the inertial and structural forces of the hood contributed to peaks of the headform deceleration in the initial and latter phases, respectively.Conclusions: Using the 2-dimensional energy derivative method, it is possible to analyze an oblique impact or a pedestrian headform impact with large rotations. This method has advantages compared to the conventional approach using cross-sectional forces because the contribution of each component to system deceleration can be determined.

Design and simulation of a rear underride protection device (RUPD) for heavy vehicles

ABSTRACTEvery year, thousands of deaths are recorded worldwide due to crashes of small cars with heavy trucks. The highest risk during collision of passengers’ car with a truck is the intrusion of passengers’ compartment under the heavy truck rear underride leading to cause fatal injuries to passengers. Design of robust underride guard of truck is one of the significant factors that should be taken into consideration within design and enhancement of truck chassis. In this study, a new rear underride protection device (RUPD) based on FMVSS 223/224 regulations is developed to enhance the crashworthiness and reduce passenger compartment intrusion under heavy trucks during accident. Finite element simulation is utilised for performance analysis of the RUPD in LS-DYNA. The results showed that the new RUPD design enhanced the energy absorption by 68.87% and reduced the occupant's car deceleration by 66.116%. The new guard is able to avoid underride of Toyota Yaris (2010) colliding at 45, 54 and 63 km/h compared with the normal guard that failed under the same test conditions.

Hybrid Engine Powered City Car: Fuzzy Controlled Approach

This study describes a fuzzy controlled hybrid engine powered car. The car is powered by the lithium ion battery capacity of 1000 Wh is charged by the 50 cc hybrid engine and power regenerative mode. The engine is operated with lean mixture at 3000 rpm to charge the battery. The regenerative mode that connects with the engine generates electrical power of 500-600 W for the deceleration of car from 90 km/h to 20 km/h. The regenerated electrical power has been used to power the air-conditioning system and to meet the other electrical power. The battery power only used to propel the car. The regenerative power also found charging the battery for longer operation about 40 minutes and more. The design flexibility of this vehicle starts with whole-vehicle integration based on radical light weighting, drag reduction, and accessory efficiency. The energy efficient hybrid engine cut carbon dioxide (CO2) and nitrogen oxides (N2O) emission about 70-80% as the loads on the crankshaft such as cam-follower and its associated rotating components are replaced by electromagnetic systems, and the flywheel, alternator and starter motor are replaced by a motor generator. The vehicle was tested and found that it was able to travel 70 km/litre with the power of hybrid engine.

Effects of Adjacent Vehicles on Judgments of a Lead Car During Car Following.

Two experiments were conducted to determine whether detection of the onset of a lead car's deceleration and judgments of its time to contact (TTC) were affected by the presence of vehicles in lanes adjacent to the lead car. In a previous study, TTC judgments of an approaching object by a stationary observer were influenced by an adjacent task-irrelevant approaching object. The implication is that vehicles in lanes adjacent to a lead car could influence a driver's ability to detect the lead car's deceleration and to make judgments of its TTC. Displays simulated car-following scenes in which two vehicles in adjacent lanes were either present or absent. Participants were instructed to respond as soon as the lead car decelerated (Experiment 1) or when they thought their car would hit the decelerating lead car (Experiment 2). The presence of adjacent vehicles did not affect response time to detect deceleration of a lead car but did affect the signal detection theory measure of sensitivity d' and the number of missed deceleration events. Judgments of the lead car's TTC were shorter when adjacent vehicles were present and decelerated early than when adjacent vehicles were absent. The presence of vehicles in nearby lanes can affect a driver's ability to detect a lead car's deceleration and to make subsequent judgments of its TTC. Results suggest that nearby traffic can affect a driver's ability to accurately judge a lead car's motion in situations that pose risk for rear-end collisions.

Combining findings from gaze and electroencephalography recordings to study timing in a visual tracking task

Electroencephalography (EEG) and gaze data have traditionally been separated in neurocognitive studies because of the artefacts that even small controlled eye movements produce. Study of gaze control in a visual tracking task provides information about an individual's prospective control. By including gaze events in the EEG analysis, we studied prospective control and its neural correlates during deceleration in a visual tracking task. Adult participants followed with their gaze a small car moving horizontally on a large screen, where the final approach of the car was temporarily occluded, and pushed a button to stop the car at the reappearance point. Two gaze events, the behavioural push button response and the nonbehavioural stimulus onset, were used to time-lock the averaged event-related potential (ERP) waveform. A significant effect of deceleration on peak amplitude in parietal channel Pz (P<0.05) was found when ERP waveforms were time-locked to the prospective gaze shift over the occluder. The peak decreased in amplitude as car deceleration increased when participants successfully stopped the car, indicating successful deceleration discrimination. No such effect was found when ERP waveforms were time-locked to any of the other events. Thus, a traditional stimulus onset time-locking procedure is likely to distort the averaged signal and consequently hide important Pz-peak amplitude differences on the prospective timing of decelerating object motion during occlusion. This study shows the importance of including behavioural data when studying neural correlates of prospective control and proposes active incorporation of behavioural data into the EEG analysis.

Application of linear optimal preview control theory to severe braking of a car

Linear optimal preview control theory is applied to severe braking of a car, providing an extension of work already reported. A new technique is developed to prepare equilibrium running states for a braking vehicle, from which linearized, small-perturbation models can be constructed, with sets of optimal preview controls following. Simulations of straight-line manoeuvres with near-limit decelerations demanded are conducted, first, with linear interpolation of trim states and control gains according to car speed and, second, with bilinear interpolation according to car speed and deceleration. A special procedure is required to compute the preview controls in the latter case. Bilinear gain scheduling over speed and deceleration is shown to give excellent tracking and tyre-force utilization in very challenging circumstances, giving substantial advantage with respect to the alternative simpler scheme.

A Petri-Net Based Context Representation in Smart Car Environment

Driving is a complex process influenced by a wide range of factors, especially complex interactions between the driver, the vehicle, and the environment. This paper represents the complex situations in smart car domain. Unlike existing context-aware systems which isolate one context situation from another, such as road congestion and car deceleration, this paper proposes a context model which considers the driver, vehicle and environment as a whole. The paper tries to discover the inherent relationship between the situations in the smart car environment, and proposes a context model to support the representation of situations and their correlation. The detailed example scenarios are given to illustrate our idea.

Responses to deceleration during car following: Roles of optic flow, warnings, expectations, and interruptions.

More than 25% of accidents are rear-end collisions. It is essential to identify the factors that contribute to such collisions. One such factor is a driver's ability to respond to the deceleration of the car ahead. In Experiment 1, we measured effects of optic flow information and discrete visual and auditory warnings (brake lights, tones) on responses to deceleration during car following. With computer simulations of car-following scenes, university students pressed a button when the lead car decelerated. Both classes of information affected responses. Observers relied on discrete warnings when optic flow information was relatively less effective as determined by the lead car's headway and deceleration rate. This is consistent with DeLucia's (2008) conceptual framework of space perception that emphasized the importance of viewing distance and motion (and task). In Experiment 2, we measured responses to deceleration after a visual interruption. Scenes were designed to tease apart the role of expectations and optic flow. Responses mostly were consistent with optic flow information presented after the interruption rather than with putative mental expectations that were set up by the lead car's motion prior to the interruption. The theoretical implication of the present results is that responses to deceleration are based on multiple sources of information, including optical size, optical expansion rate and tau, and discrete warnings that are independent of optic flow. The practical implication is that in-vehicle collision-avoidance warning systems may be more useful when optic flow is less effective (e.g., slow deceleration rates), implicating a role for adaptive collision-warning systems.

Car Deceleration Considering Its Own Velocity in Cellular AutomataModel

In this paper, we propose a new cellular automaton model, which isbased on NaSch traffic model. In our method, when a car has a largervelocity, if the gap between the car and its leading car is not enoughlarge, it will decrease. The aim is that the following carhas a buffer space to decrease its velocity at the next time, and thenavoid to decelerate too high. The simulation results show that using ourmodel, the car deceleration is realistic, and is closerto the field measure than that of NaSch model.

Effects of Optical Flow and Discrete Warnings on Deceleration Detection during Car Following

Tau specifies time-to-contact between a driver and a lead car, and is potentially useful to prevent rear-end collisions. However, studies suggest that time-to-contact judgments are based on multiple information sources and that effective information varies with distance. We focused on three questions: Does a driver's response to a lead car's deceleration occur when the car's optical size, expansion rate, or tau reaches a “critical” value? Does effective information differ for near and far lead cars? Is a driver's response affected by discrete warnings (brake lights and auditory warnings) that occur independently of optical flow information? Results suggested that responses were not based on a critical value of the optical parameters considered here, and were affected by discrete warnings. Further, effective information varied with the distance and deceleration rate of the lead car. Results were consistent with prior proposals that advanced brake warning systems and collision-avoidance warning systems can reduce the incidence of rear-end collisions. Future studies of this kind will help to improve the design of collision-avoidance systems and to reduce rear-end collisions.

Effects of the Body and Seatbelt Design on Occupant Impact in Car Crash

In the automobile frontal collision, the maximum value of the chest deceleration is one of the most important performance indexes for the occupant protection, and depends on the time history of the car deceleration. Therefore, it is important to analyze the relationship between the chest and car deceleration, and find the car crash characteristic which causes the minimum chest deceleration. In the most research, 2 DOF model (car and occupant) at translation motion was generally used. However, it is difficult to understand an occupant impact because a real occupant is restrained by the shoulder and lap seatbelt and the upper body has rotational motion during a collision. In this paper, the relationship between the chest and car deceleration were analyzed by 4 DOF model taking into consideration its rotation. Moreover the effect of a force limiter of a seatbelt was also examined. Based on the theoretical and experimental results, we derived the knowledge for an optimum automotive crash design.

Analysis of the Influence of Energy Dissipative Under-Ride Guard's Parameters on Car-to-Truck Collision

Rear underrun crashes involving heavy vehicles have the most tragic consequences. This paper describes the concept of a special energy dissipative rear under-ride guard. A dynamic model of a car-to-truck collision was built where the truck had been equipped with such a guard. Simulation research of this model was made. The purpose of this study is to determine the influence of linear and non-linear characteristics of stiffness and damping on the collision course. Maximal value of the car deceleration during the collision was chosen as the major criterion of the bumper quality. The analyses confirm that the proposed bumper, in spite of the concept's simplicity, can be a very effective way of providing security during such a car-to-truck collision. (A)

A car-following collision prevention control device based on the cascaded fuzzy inference system

A car-following collision prevention control device based on the cascaded fuzzy inference system (CFIS), consisting of a velocity fuzzy controller and an acceleration fuzzy controller, to nonlinearly control car acceleration or deceleration rate is proposed. The distance and speed relative to the car in front are measured using spread spectrum radar and applied to the collision prevention control device. The output acceleration or deceleration rate obtained from the CFIS car-following collision prevention system is based on the characteristics of the vehicle. The simulation results demonstrate that the presented CFIS control device can solve the oscillation problems for final relative distance between the lead vehicle (LV) and following vehicle (FV) and relative speed. When the LV applies the brake suddenly or a stationary obstacle appears in front of vehicle moving at high speed on the roadway, the CFIS control device can safely avoid a collision. The CFIS car-following collision prevention control device proposed in this paper can provide a safe, reasonable and comfortable drive.

The Development of a Computer Simulation Model of Driver Performance to Predict Accident Probability

The National Highway Traffic Safety Administration (NHTSA) is sponsoring the development of a computer simulation model of driver/vehicle system performance in various accidently likely traffic scenarios. Its acronym is DRIVEM ( Driver Vehicle Effectiveness Model). By modeling driver detection of critical events (e.g., lead car deceleration), evasive maneuver decision making, control inputs, and the subsequent vehicle trajectory, DRIVEM can translate the diverse research data on driver performance into quantitative predictions of accident probability. When the model is fully developed, NHTSA will have an analytic tool to permit it to quickly and inexpensively compare alternative crash avoidance measures. This paper summarizes the development of DRIVEM, its submodels, its limitations, and needed refinements.