1,720,981 research outputs found
Examination of the use of fuzzy sets to describe relative speed perception
No full textIn recent years a range of new methods have been proposed with which to describe and evaluate driver behaviour. One such method is that of fuzzy logic, where variables used in the driver decision-making process may be described linguistically, allowing a quantifiable degree of uncertainty to be introduced. This paper explores the use of such a formalism to describe the driver perception of 'closing speed' between two vehicles engaged in 'car-following' on a motorway, and by using data from an instrumented vehicle experiment, it tests a number of models using relative speed, visual angle and the time to collision. Several of these models fit the data quite well, and there is both a small positive perception bias present and a number of reversals in sign judgement. Additionally, a brief examination is made of potential variations on the methodology that may both make data collection easier and/or allow a 'more fuzzy' representation to be made
Car following: a historical review
No full textIn recent years, the topic of car-following has become of increased importance in traffic engineering and safety research. Models of this phenomenon, which describe the interaction between (typically) adjacent vehicles in the same lane, now form the cornerstone for many important areas of research including (a) simulation modelling, where the car-following model (amongst others) controls the motion of the vehicles in the network, and (b) the functional definition of advanced vehicle control and safety systems (AVCSS), which are being introduced as a driver safety aid in an effort to mimic driver behaviour but remove human error. Despite the importance of this area however, no overview of the models availability and validity exists. It is the intent of this paper therefore to briefly assess the range of options available in the choice of car-following model, and assess just how far work has proceeded in our understanding of what, at times, would appear to be a simple process
Dynamic properties of models of modulated systems in condensed matter
No full textSIGLEAvailable from British Library Document Supply Centre- DSC:DX92268 / BLDSC - British Library Document Supply CentreGBUnited Kingdo
A collision model for safety evaluation of autonomous intelligent cruise control
No full textThis paper describes a general framework for safety evaluation of autonomous intelligent cruise control in rear-end collisions. Using data and specifications from prototype devices, two collision models are developed. One model considers a train of four cars, one of which is equipped with autonomous intelligent cruise control. This model considers the car in front and two cars following the equipped car. In the second model, none of the cars is equipped with the device. Each model can predict the possibility of rear-end collision between cars under various conditions by calculating the remaining distance between cars after the front car brakes. Comparing the two collision models allows one to evaluate the effectiveness of autonomous intelligent cruise control in preventing collisions. The models are then subjected to Monte Carlo simulation to calculate the probability of collision. Based on crash probabilities, an expected value is calculated for the number of cars involved in any collision. It is found that given the model assumptions, while equipping a car with autonomous intelligent cruise control can significantly reduce the probability of the collision with the car ahead, it may adversely affect the situation for the following cars.<br/
Findings on the approach process between vehicles on motorways
No full textOver the past 10 years there has been a growing body of research into modeling and describing driving behavior, particularly for situations that occur on motorways. This interest has arisen from the need to assess safety and capacity benefits that could be produced by changes to road design, operation, signage, and in-vehicle advanced transport telematics, such as collision warning (CW) or autonomous cruise control. For the most part these investigations have focused on "close" or "car" following, which describes the maintenance of a time- or distance-based following headway. However, often overlooked, and of equal importance, is the "approach" process, describing how a driver decelerates when approaching a slower vehicle. There are several competing theories of the behavioral basis underlying this process, including, for example, those based on time-to-collision or optic flow. There are, however, very few data against which such models can be assessed and systems designed. Presented are the results from an exploratory, instrumented vehicle study designed to assess approach mechanisms. The two key features of the process are explored: the circumstances under which driver deceleration is instigated, and the process governing the control of the deceleration itself. Finally, there is a brief assessment of the implications of these findings for the design of CW systems, in which realistic warnings may prove vital to their acceptance by the driving public.<br/
A linear dynamic model for driving behavior in car following
No full textA car-following model is formulated as a time-continuous dynamic process, depending on two parameters and two inputs. One of these inputs is the follower's desired equilibrium spacing, assumed to exist and to be known. Another input is the speed of the lead vehicle. Given the formulation of the model, the contribution of these two inputs is separable from an analytical point of view. The proposed model is simple enough (whereas not being simplistic) to support real-time applications in the field of advanced driving assistance systems. Starting from the equilibrium spacing, it is possible to estimate the parameters of the model, allowing for a full identification procedure. The modeling framework was prevalidated against observed data from two different data sets, collected by means of two instrumented vehicles in independent experiments, carried out in Italy and the United Kingdom. The validation proved that the proposed car-following model gives good results not only around the desired equilibrium spacing but also in general car-following conditions. The experimental data sets are discussed in terms of parameter values as well as performance of the dynamic process against observed data
What is the answer? And come to that, what are the questions?
No full textThis paper replies to the issues raised by commentators on Brackstone and McDonald’s historical review of car following. It focuses on the implications of satisficing, the determinism assumed in engineering inspired models of car following, and the role that individual differences in perceptual and cognitive performance, as well as motivation, must play in future accounts of traffic behaviours such as car following
Determinants of following headway in congested traffic
Full text linkThis paper reports on results of a study undertaken in the U.K. aimed at investigating factors affecting the car following process. An understanding of the factors affecting this complex decision making process is essential to a wide range of theoretical issues including driver workload, capacity and the modeling of freeway flow, as well as practical applications such as the design of in-vehicle driver aids and assistance systems, many of which have direct relevance to increasing driver safety. The study used an instrumented vehicle to collect time dependent following data for a group of test drivers. Data was collected on two differing types of high speed road, using six primary subjects who drove a test vehicle, supplemented by data on one hundred and twenty three drivers that were observed following the test vehicle.
Examination was made of how the time headway chosen by a driver is influenced by a range of situational variables commonly believed to effect behavior, with four main findings. Firstly, headway was found to change according to the type of vehicle being followed (i.e. subjects followed closer to trucks than to cars), secondly, little variation was found with changes in overall traffic flow, thirdly, little correlation was found with road type, and lastly a distinct day-to-day variation in individual behavior was observed
Vehicle to vehicle communication based convoy driving and potential applications of GPS
No full textTraffic congestion is forecasted to continue growing. Simply building more roads is believed not a solution. Many studies have been made to investigate the application of convoy driving or Automated Highway System (MIS) to release increasingly congested motorway, smooth motorway traffic flow, reduce journal tim: and increase road capacity.The paper includes the introduction of a convoy driving system, discussions on potential impacts of the convoy driving system and the possibility of using differential GPS system (DGPS) for accurate vehicle locating in convoy driving system
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