Subject Vehicle Research Articles

Intervehicle Transmission Rate Control for Cooperative Active Safety System

We propose an intervehicle communication framework for the cooperative active safety system (CASS) whose operation is based on the dissemination of each vehicle's state information through a wireless network. Such a CASS requires each subject vehicle to be aware of its surroundings, particularly of the motion and position of other vehicles in its proximity. In this paper, we assume that all vehicles are equipped with onboard communication devices. In such situations, the wireless channel is simultaneously shared by a large number of vehicles, and one of the most difficult challenges in designing CASS is to maintain real-time tracking accuracy of neighboring vehicles while avoiding network congestion and failure. To address this issue, we analyze the problem that multiple scalar linear time-invariant dynamical systems track each other over a multiaccess channel, and then, we propose a rate adaptation algorithm to distributively control the self-information broadcast behavior of each vehicle. The proposed algorithm uses a closed-loop control concept and accounts for the lossy channel. Simulation results show that, if the message generation rate is dynamically adjusted in an on-demand fashion, more accurate and robust tracking performance can be achieved under various traffic conditions.

Service delay analysis at TWSC intersections through simulation

The service delay experienced by the different priority movements at unsignalized intersection in mixed traffic under varying composition of conflicting traffic is studied using simulation technique. Basic curves of service delay for various priority movements are developed for four types of subject vehicles namely passenger car, three wheeler, two wheeler and heavy vehicle facing the conflicting stream of cars. The conflicting traffic stream of passenger cars was also changed later to the stream of cars and one of the remaining three vehicles in its different proportions and the effect on service delay was evaluated. It was found that service delay to a priority movement increases when conflicting traffic stream was of heterogeneous type. An easy to use procedure is suggested for determining the service delay for a type of subject vehicle executing a maneuver, for a given composition of conflicting traffic.

Impact on Driver Behavior of Steady-Burn Warning Lights on Channelizing Drums in Work Zones

Research was performed to explore the impact on driver behavior of steady-burn warning lights on drums used in highway work zones in the state of Michigan. Various characteristics related to nighttime driver behavior were evaluated with data collected in actual work zones. Thirty-six randomly selected work zones in 15 counties throughout lower Michigan were investigated in this study. Collectively, the work zones represented a broad range of commonly occurring scenarios. Work zones that used drums with steady-burn warning lights and work zones that did not were examined in a comparative parallel study. Data on nighttime driver behavior were collected by recording the movements of randomly selected subject vehicles as they were followed by a survey vehicle through the study work zones. For each subject vehicle, three measures of driver behavior were collected. The measures were (a) percent of time spent in the center lane position, (b) percent of time spent in the lane position closest to the drums, and (c) rate of steering reversals per minute. The data were compared by using analysis of variance techniques. The results showed that the presence of steady-burn warning lights on drums used to channelize traffic in work zones did not significantly affect either the time vehicles spent in the center lane position or the rate of steering reversals. The presence of steady-burn warning lights did, however, increase the tendency of drivers to travel in relatively close proximity to the drums. Collectively, the research findings suggest that the use of steady-burn warning lights on channelizing drums in work zones does not have a substantive impact on nighttime driver behavior.

Impact of Driver and Surrounding Traffic on Vehicle Deceleration Behavior at Onset of Yellow Indication

This paper discusses driver deceleration levels in a controlled field environment at the onset of a yellow indication on high-speed signalized intersection approaches using an in-vehicle differential Global Positioning System. The impacts of driver gender, driver age, roadway grade, mean approach speed, platooning scenarios (leading, following, or alone), and time to intersection (TTI) on driver deceleration levels were analyzed. This information is critical for the efficient and safe design of traffic signal clearance timings. The IntelliDrive initiative can gather information about the driver, subject vehicle, and surrounding traffic conditions to execute safe and customizable traffic signal indication change warnings. The results indicate that driver deceleration levels are significantly higher than the 3-m/s2 deceleration level used in the state-of-the-practice traffic signal design guidelines. The mean deceleration level is 3.6 to 4.1 m/s2. The results can be used to enhance the design of yellow timings and may be integrated with the new IntelliDrive initiative to provide customizable driver warnings. The results demonstrate that driver deceleration levels are higher at shorter TTIs at the onset of yellow. Drivers are willing to exert deceleration levels in excess of 7 m/s2 at short TTIs (less than 2.5 s). Furthermore, older drivers (60 years of age or older) employ greater deceleration levels compared with younger (under 40 years old) and middle-aged (between 40 and 59 years old) drivers. A driver following another vehicle that proceeds legally through an intersection without stopping exerts higher deceleration levels than drivers driving alone on a roadway or leading another vehicle, and drivers leading a platoon of vehicles are not affected by vehicles behind them.

A kinetic energy model of two-vehicle crash injury severity

An important part of any model of vehicle crashes is the development of a procedure to estimate crash injury severity. After reviewing existing models of crash severity, this paper outlines the development of a modelling approach aimed at measuring the injury severity of people in two-vehicle road crashes. This model can be incorporated into a discrete event traffic simulation model, using simulation model outputs as its input. The model can then serve as an integral part of a simulation model estimating the crash potential of components of the traffic system. The model is developed using Newtonian Mechanics and Generalised Linear Regression. The factors contributing to the speed change (ΔVs) of a subject vehicle are identified using the law of conservation of momentum. A Log-Gamma regression model is fitted to measure speed change (ΔVs) of the subject vehicle based on the identified crash characteristics. The kinetic energy applied to the subject vehicle is calculated by the model, which in turn uses a Log-Gamma Regression Model to estimate the Injury Severity Score of the crash from the calculated kinetic energy, crash impact type, presence of airbag and/or seat belt and occupant age.

Intelligent vehicle safety control strategy in various driving situations

This paper describes a safety control strategy for intelligent vehicles with the objective of optimally coordinating the throttle, brake, and active front steering actuator inputs to obtain both lateral stability and longitudinal safety. The control system consists of a supervisor, control algorithms, and a coordinator. From the measurement and estimation signals, the supervisor determines the active control modes among normal driving, longitudinal safety, lateral stability, and integrated safety control mode. The control algorithms consist of longitudinal and lateral stability controllers. The longitudinal controller is designed to improve the driver's comfort during normal, safe-driving situations, and to avoid rear-end collision in vehicle-following situations. The lateral stability controller is designed to obtain the required manoeuvrability and to limit the vehicle body's side-slip angle. To obtain both longitudinal safety and lateral stability control in various driving situations, the coordinator optimally determines the throttle, brake, and active front steering inputs based on the current status of the subject vehicle. Closed-loop simulations with the driver–vehicle-controller system are conducted to investigate the performance of the proposed control strategy. From these simulation results, it is shown that the proposed control algorithm assists the driver in combined severe braking/large steering manoeuvring so that the driver can maintain good manoeuvrability and prevent the vehicle from crashing in vehicle-following situations.

Multi-vehicle target selection for adaptive cruise control

This paper presents a target selection strategy for adaptive cruise control (ACC) in multiple vehicle traffic situations. Since there are many vehicles in a real road and various transitions between the subject vehicle and the neighbouring vehicles occurred, it is important to establish a target selection and a control strategy for applying the ACC system to multiple vehicle traffic scenes in order to improve the driver acceptance and the vehicle safety. For this purpose, it is necessary to determine which neighbouring vehicle is an important target for the adaptive cruise control and prevention of collision depending on a driving situation. A primary target selection algorithm decides an in-lane target and provides the information to a longitudinal controller in order to drive a subject vehicle smoothly and to ensure safety in multi-vehicle traffic situations. The proposed selection algorithm consists of an in-lane target detection, a motion-based analysis and an integration process. The performance and safety benefits of a multi-vehicle ACC system with proposed target selection strategy are investigated via simulations using several driving scenarios. Simulation results show that the system response is smooth and safe even in multiple vehicle driving situations.

Modeling Vehicle Interactions during Lane-Changing Behavior on Arterial Streets

Lane-changing algorithms have attracted increased attention during recent years in traffic modeling. However, little has been done to address the competition and cooperation of vehicles when changing lanes on urban streets. The main goal of this study is to quantify the vehicle interactions during a lane-changing maneuver. Video data collected at a busy arterial street in Gainesville, Florida, was used to distinguish between free, forced, and competitive/cooperative lane changes. Models particularly for competitive/cooperative lane changes were developed, depending on whether the following vehicle cooperates with the subject vehicle or not. By referring to the TCP/IP protocol in computer network communications, a sequence of 'hand-shaking' negotiations were designed to handle the competition and cooperation among vehicles. The developed model was implemented and validated in the CORSIM microsimulator package, with the simulation capabilities compared against the original lane-changing model in CORSIM. The results indicate that the new model better replicates the observed traffic under different levels of congestion.

Design of a Longitudinal Driving/Safety Control Algorithm in Multi-Vehicle Traffic Situations

This paper presents a longitudinal driving/safety control algorithm in multiple vehicle traffic situations. Since there are many vehicles in a real road and various transitions between the subject vehicle and the neighboring vehicles are occurred, it is important to establish an integrated longitudinal control algorithm which provides comfort vehicle behavior and uses a large deceleration to maintain safe vehicle-to-vehicle clearance in multi-vehicle traffic situations. For this purpose, it is necessary to determine which the neighboring vehicle is an important target for the adaptive cruise control and prevention of collision depending on a driving situation. In addition, it is required to calculate the desired acceleration in order to improve the driver acceptance and the vehicle safety. The performance and safety benefits of the proposed longitudinal driving/safety control algorithm are investigated via simulations using several driving scenarios. Simulation results show that the system response is smooth and safe even in multiple vehicle driving situations.

주행 안전을 위한 통합 샤시 제어

This paper describes an integrated chassis control for a maneuverability, a lateral stability and a rollover prevention of a vehicle by the using of the ESC and AFS. The integrated chassis control system consists of a supervisor, control algorithms and a coordinator. From the measured and estimation signals, the supervisor determines the vehicle driving situation about the lateral stability and rollover prevention. The control algorithms determine a desired yaw moment for lateral stability and a desired longitudinal force for the rollover prevention. In order to apply the control inputs, the coordinator determines a brake and active front steering inputs optimally based on the current status of the subject vehicle. To improve the reliability and to reduce the operating load of the proposed control algorithms, a multi-core ECU platform is used in this system. For the evaluation of this system, a closed loop simulations with driver-vehicle-controller system were conducted to investigate the performance of the proposed control strategy.

Estimation of rear-end crash potential using vehicle trajectory data

Recent advancement in traffic surveillance systems has allowed for obtaining more detailed vehicular movement such as individual vehicle trajectory data. Understanding the characteristics of interactions between leading vehicle and following in the traffic flow stream is a backbone for designing and evaluating more sophisticated traffic and vehicle control strategies. This study proposes a methodology for estimating rear-end crash potential, as a probabilistic measure, in real time based on the analysis of vehicular movements. The methodology presented in this study consists of two components. The first estimates the probability that a vehicle's trajectory belonging to either 'changing lane' or 'going straight'. A binary logistic regression (BLR) is used to model the lane-changing decision of the subject vehicle. The other component derives crash probability by an exponential decay function using time-to-collision (TTC) between the subject vehicle and the front vehicle. Also, an aggregated measure, crash risk index (CRI) is used in the analysis to accumulate rear-end crash potential for each subject vehicle. The result of this study can be used in developing traffic control and information systems, in particular, for crash prevention.

Dilemma Zone Driver Behavior as a Function of Vehicle Type, Time of Day, and Platooning

A comprehensive investigation of the influence of vehicle type on various aspects of dilemma zone driver behavior, including brake response time, deceleration rate, and red light running occurrence, was performed at six urban or suburban signalized intersections in Wisconsin. Driver behavior data were obtained for 1,275 vehicles that were between 2.0 and 6.5 s upstream of the intersection at the onset of the yellow interval. Each vehicular observation was classified into one of five vehicle type categories: motorcycle, car, light truck (pickup, SUV, van, minivan), single-unit truck (single-unit heavy truck, delivery truck, recreation vehicle, bus), and tractor trailer (multiunit heavy truck). Each observation was also classified by time of day and whether the subject vehicle was part of a platoon. Vehicle type had a statistically significant effect on deceleration rate and red light running occurrence but did not have an effect on brake response time. Deceleration rates were highest for cars and light trucks; single-unit trucks and tractor trailers showed the lowest deceleration rates. Tractor trailers were 3.6 times more likely and single-unit trucks were 2.5 times more likely to commit red light running compared with passenger vehicles. The rates of red light running for cars and light trucks were not substantially different from each other. Time of day (peak versus off-peak) had a statistically significant effect on both deceleration rate and occurrence of red light running. Deceleration rates were significantly higher during off-peak times. Red light running was 1.3 times more likely to occur during peak periods compared with off-peak periods. Platooning had no effect on any of the measures of effectiveness.

Forensic Engineering Studies Using Exemplar Vehicles And Surrogates In Vehicle Impact Cases

As Part Of Their Event Reconstruction, Accident Reconstructionists Often Inspect Exemplar Motor Vehicles. xemplarmeans A Vehicle Of The Same Model, Production Series, Etc. In Terms Of The Vehicle Of Interest. In The Analysis Of The Injury Aspects Of Vehicular Collisions, Biomechanics Experts Can Also Benefit From Exemplar Studies, Especially When A Surrogate (Individual Of The Same Gender, Age Group, Body Stature, Etc.) Is Incorporated Into The Study. This Is Often An Important Activity Since Available Physical Evidence Is Often Limited. For Example, Photo Documentation May Focus Almost Exclusively On The Outside Of The Subject Vehicle, Whereas The Injury Event(S) Often Occur Within The Vehicle. Also, Providers Of Vehicle Specifications Typically Provide Limited (If Any) Vehicle Interior Information. Finally, Depositional Information May Be Very Limited, Providing Few Details On Events And Conditions That May Have Contributed (Or Not) To Claimed Injuries. Thus, Exemplar/Surrogate Studies Can Provide A Wealth Of Information In The Analysis Of What Injuries May (Or May Not) Have Occurred Knowing The Physics Of The Accident Reconstruction And The Resulting Occupant Kinematics, Geometric Considerations, Claimant Characteristics, And The Associated Injury Mechanisms. A Series Of Situations Will Be Presented As Examples Of How Exemplar/Surrogate Studies Can Be Useful In Injury Analysis, Including Seat Belt Issues, Rear-End Collisions, And Pedestrian/Vehicle Incidents. General Protocol Considerations Will Also Be Presented.

Stochastic Dilemma Hazard Model at High-Speed Signalized Intersections

Dilemma zone (DZ) is an area where drivers can neither stop comfortably nor cross safely when they are presented with a yellow indication at an intersection. The DZ problem is a leading cause for crashes at high-speed signalized intersections. Researchers traditionally assume that vehicles in DZ are equally hazardous and therefore they use the number of vehicles in DZ as an indicator of safety. There is, however, a general understanding among researchers that a DZ-associated accident potential (dilemma hazard thereafter) will vary depending on the subject vehicle's position and speed at the yellow onset. Based on the previous studies on drivers' response to the yellow onset, vehicle kinematics, and a Monte Carlo simulation framework, we present a dilemma hazard model for vehicles in the DZ. In light of this model, each vehicle in DZ is assigned a hazard weight according to its position and speed when the yellow is presented. The proposed model is calibrated and validated using the vehicle trajectory data collected at a high-speed signalized intersection in Christiansburg, Va. Finally, the dilemma hazard model is used to obtain optimal clearance interval for the study site.

Factors Related to Drivers' Braking Operation in Response to a Crossing Vehicle Approaching from the Side Direction

We conducted driving simulator experiments with 15 participants to identify factors related to drivers’ judgment of when and how to brake. We set up a situation in which a subject vehicle encountered a target vehicle at an open non-signalized intersection to simulate a crossing collision. Drivers in the subject vehicle were instructed to apply the brakes when they felt danger. Factors investigated were azimuth angle to the target vehicle, position of target vehicle when the subject vehicle arrives at an intersection, visual angle of target vehicle, and relative distance between subject vehicle and target vehicle. We analyzed both their time differentials and increase rates. Statistical analysis indicated that the factors most closely related to the drivers’ braking judgment are relative distance between subject vehicle and target vehicle, and azimuth angle to the target vehicle.

Multi-Vehicle Adaptive Cruise Control with Collision Avoidance in Multiple Transitions

This paper presents a longitudinal control algorithm for an adaptive cruise control (ACC) with collision avoidance (CA) in multiple transitions by a driver and traffic conditions. The objective is for smooth and safe transition between various driving situations to achieve driver's comfort and prevention of collision. The proposed algorithm consists of a multi-target tracking filter, a primary target selection algorithm and an integrated ACC/CA controller. The multi-target tracking filter is used to smooth the sensor signal, and makes it possible to apply to a control system. The primary target selection algorithm decides an important target which has an effect on the subject vehicle. In addition, it provides the information to an integrated ACC/CA controller in order to drive a subject vehicle smoothly and improve safety in various traffic transitions. Finally, the integrated ACC/CA controller computes the desired acceleration. In order to reduce the effects of discontinuous change by drivers such as time gap, set speed, and automation switching, an input-shaping filter technique is applied to integrated ACC/CA controller. The performance and safety benefits of the multi-vehicle ACC/CA system is investigated via simulations using real data on driving. Simulation results show that the response of multi-vehicle ACC/CA system is more smooth and safer in multiple transitions.

Design, tuning, and evaluation of a full-range adaptive cruise control system with collision avoidance

This paper describes the design, tuning, and evaluation of a full-range adaptive cruise control (ACC) system with collision avoidance (CA). The control scheme is designed to improve drivers’ comfort during normal, safe-driving situations and to completely avoid rear-end collision in vehicle-following situations. Driving situations are divided into safe, warning, and dangerous modes. Three different control strategies have been proposed, depending on the driving situation. The driving situations are determined using a non-dimensional warning index and the time-to-collision (TTC). The control parameters of the proposed ACC/CA system are tuned by a confusion-matrix method using manual-driving data in no-crashing driving situations. The vehicle-following characteristics of the subject vehicle were compared to real-world, manual-driving data. Finally, the ACC/CA system was also implemented in a real vehicle and tested in both safe-traffic and severe-braking situations. It is shown that the proposed control strategy can provide natural following performance that is similar to human manual-driving in both high-speed driving and low-speed stop-and-go situations. Furthermore, it can prevent the vehicle-to-vehicle distance from dropping to an unsafe level in a variety of driving conditions.

Effect of In-Vehicle Touch Screen Position on Driver Performance

The effect of touch-screen monitor placement on in-vehicle task performance and driving performance was examined in a driving simulator. Sixteen subjects drove behind a lead vehicle while interacting with a menu-based interface that required looking, planning, reaching, and touching. The vehicle dynamics of the simulator were adjusted to simulate two vehicles: a normal-weight car and a heavy-weight truck. The monitor was placed in one of four different positions that had varying levels of visual and physical difficulty. Two positions had a short reach distance and two had a long reach distance. For each monitor pair, one position had a shorter visual distance from the road ahead and one had a longer visual distance. Monitor positions that were at greater visual distances from the road ahead or that were farther physically from the subject resulted in longer in-vehicle task completion times. The average task time increased from 17.8 seconds for the closest monitor position to 35.1 seconds for the farthest. Although driving performance, as measured by the RMS error between the subject vehicle and the lead vehicle and delay in speed change, was adversely affected by performance of an in-vehicle task, it was relatively unaffected by monitor position.

2108 横方向からの接近車両に対するブレーキ操作に影響を及ぼす要因(OS6-2 運転行動と車両挙動,OS6 ヒューマンファクタ,オーガナイズド・セッション)

Authors conducted driving simulator experiments to reveal factors which are related to the drivers' judgment of braking using 15 participants. We set up the situation in which a subject vehicle encountered a target vehicle at an open intersection to simulate a crossing collision. Drivers in the subject vehicle were instructed to apply the brakes when they felt dangerous. Candidate factors are azimuth angle to the target vehicle, reaching distance of target vehicle, visual angle of target vehicle, and relative distance between subject vehicle and target vehicle. We analyzed their time differentials and dilating rates as well. Using statistical analysis we found that factors, which are relative distance between subject vehicle and target vehicle, and azimuth angle to the target vehicle are most closely related to the drivers' braking judgment.

Idaho Explosives Detection System: Development and Enhancements

The Idaho Explosives Detection System (IEDS) was developed at the Idaho National Laboratory (INL) to respond to threats imposed by delivery trucks carrying bulk explosives into military bases. The system consists of two platforms, one on each side of a subject vehicle. Each platform includes a neutron generator and an array of sodium iodide (NaI) detectors. The two neutron generators are pulsed and synchronized. A computer connects to the system via Ethernet and is able to control the system remotely. The system was developed to detect bulk explosives in a medium size truck within a 5-min measurement time. In 2004, a full-scale prototype IEDS was built for testing and continued development. System performance was successfully tested at the INL from November 2005 to February 2006 using different types of real explosives with a variety of cargo. Recently, the first deployable prototype system was installed at Wright–Patterson Air Force Base in Ohio and has been in operation since May 2007. The capability of passively detecting radiological material within a delivery truck has also been added.