scholarly journals A time gap-based spacing policy for full-range car-following

2017 ◽  
Author(s):  
Carlos Flores ◽  
Vicente Milanes ◽  
Fawzi Nashashibi
Keyword(s):  
Full Range ◽  
Car Following ◽  
Time Gap

scholarly journals An Investigation into the Appropriateness of Car-Following Models in Assessing Autonomous Vehicles

Sensors ◽  
2021 ◽  
Vol 21 (21) ◽  
pp. 7131
Author(s):  
Akito Higatani ◽  
Wafaa Saleh
Keyword(s):  
Collision Avoidance ◽  
Autonomous Vehicles ◽  
Full Range ◽  
Detection Range ◽  
Car Following ◽  
Car Following Model ◽  
System Module ◽  
Time Gap ◽  
Collision Avoidance System ◽  
Almost All

The dramatic progress of Intelligent Transportation Systems (ITS) has made autodriving technology extensively emphasised. Various models have been developed for the aim of modelling the behaviour of autonomous vehicles and their impacts on traffic, although there is still a lot to be researched about the technology. There are three main features that need to be represented in any car-following model to enable it to model autonomous vehicles: desired time gap, collision avoidance system and sensor detection range. Most available car-following models satisfy the first feature, most of the available car-following models do not satisfy the second feature and only few models satisfy the third feature. Therefore, conclusions from such models must be taken cautiously. Any of these models could be considered for updating to include a collision avoidance-system module, in order to be able to model autonomous vehicles. The Helly model is car-following model that has a simple structure and is sometimes used as the controller for Autonomous Vehicles (AV), but it does not have a collision avoidance concept. In this paper, the Helly model, which is a very commonly used classic car-following model is assessed and examined for possible update for the purpose of using it to model autonomous vehicles more efficiently. This involves assessing the parameters of the model and investigating the possible update of the model to include a collision avoidance-system module. There are two procedures that have been investigated in this paper to assess the Helly model to allow for a more realistic modelling of autonomous vehicles. The first technique is to investigate and assess the values of the parameters of the model. The second procedure is to modify the formula of that model to include a collision avoidance system. The results show that the performance of the modified full-range Auto Cruising Control (FACC) Helly model is superior to the other models in almost all situations and for almost all time-gap settings. Only the Alexandros E. Papacharalampous’s Model (A.E.P.) controller seems to perform slightly better than the (FACC) Helly model. Therefore, it is reasonable to suggest that the (FACC) Helly model be recommended as the most accurate model to use to represent autonomous vehicles in microsimulations, and that it should be further investigated.

scholarly journals An Extended Car-Following Model considering the Driver’s Desire for Smooth Driving and Self-Stabilizing Control with Velocity Uncertainty

2020 ◽  
Vol 2020 ◽  
pp. 1-17
Author(s):  
Shihao Li ◽  
Ting Wang ◽  
Rongjun Cheng ◽  
Hongxia Ge
Keyword(s):  
Traffic Flow ◽  
Linear Stability ◽  
Traffic Congestion ◽  
The Self ◽  
Historical Time ◽  
Velocity Data ◽  
Car Following ◽  
Stabilizing Control ◽  
Car Following Model ◽  
Time Gap

In this paper, an extended car-following model with consideration of the driver’s desire for smooth driving and the self-stabilizing control in historical velocity data is constructed. Moreover, for better reflecting the reality, we also integrate the velocity uncertainty into the new model to analyze the internal characteristics of traffic flow in situation where the historical velocity data are uncertain. Then, the model’s linear stability condition is inferred by utilizing linear stability analysis, and the modified Korteweg-de Vries (mKdV) equation is also obtained to depict the evolution properties of traffic congestion. According to the theoretical analysis, we observe that the degree of traffic congestion is alleviated when the control signal is considered, and the historical time gap and the velocity uncertainty also play a role in affecting the stability of traffic flow. Finally, some numerical simulation experiments are implemented and the experiments’ results demonstrate that the control signals including the self-stabilizing control, the driver’s desire for smooth driving, the historical time gap, and the velocity uncertainty are of avail to improve the traffic jam, which are consistent with the theoretical analytical results.

scholarly journals Steady-State Car-Following Time Gaps: An Empirical Study Using Naturalistic Driving Data

2019 ◽  
Vol 2019 ◽  
pp. 1-9 ◽  
Author(s):  
Amara Loulizi ◽  
Youssef Bichiou ◽  
Hesham Rakha
Keyword(s):  
Steady State ◽  
Goodness Of Fit ◽  
Statistical Tests ◽  
Chi Square ◽  
Large Variability ◽  
Empirical Measures ◽  
Car Following ◽  
Access Road ◽  
Time Gap ◽  
Naturalistic Driving

The time gap is defined as the time difference between the rear of a vehicle and the front of its follower, which affects both safety and the saturation flow rate of a roadway segment. In this study, naturalistic driving data were examined to measure time gaps from seven different drivers in a car-following scenario within steady-state conditions. The measurements were taken from a 13-km section of a Dulles Airport access road in Washington, DC. In total, 168,053 time gap samples were obtained covering seven speed intervals. Analysis of the data revealed a large variation in time gaps within individual drivers’ driving data, with coefficients of variation as high as 63.8% observed for some drivers. Results also showed that the variability within drivers was more significant at speeds higher than 54 km/h. In addition, there was a large variability between drivers. At speeds above 108 km/h, minimum time gaps left by some drivers could be 1.6 times longer than those left by others. Several statistical distributions were used to fit the data of the seven drivers as well as the data for all drivers combined for each speed interval. The selected distributions passed the goodness-of-fit (Kolmogorov-Smirnov, Chi-square, and Anderson-Darling) criteria only when the number of samples was reduced. Data reduction was not performed randomly, but rather in a manner intended to maintain the same observed distribution when all the samples were used. It is therefore recommended that empirical measures of distributions be used in traffic microsimulation software rather than theoretically fit distributions obtained based on statistical tests. This will lead to better naturalistic traffic behavior simulations, resulting in more precise predicted measures of performance (travel time, fuel consumption, and gas emissions).

Some Effects of Alcohol on Car Driving on Two-Lane and Limited-Access Highways

1979 ◽  
Vol 23 (1) ◽  
pp. 254-258
Author(s):  
R. G. Mortimer ◽  
S. P. Sturgis
Keyword(s):  
Placebo Group ◽  
Blood Alcohol Concentration ◽  
Lateral Position ◽  
Alcohol Concentration ◽  
Alcohol Group ◽  
Car Following ◽  
Limited Access ◽  
Time Gap ◽  
Instrumented Vehicle ◽  
Car Driving

The purpose of this study was to investigate the effect of moderate doses of alcohol on a number of driving skills involved in steering and car-following, and passing decision-making. Forty drivers drove an instrumented vehicle on two-lane and limited-access highways either at night or in the daytime and either when sober or after having consumed alcohol to achieve a mean blood alcohol concentration of 0.085%. Seven tests were conducted with each subject consisting of: passing gap time judgments, car-following with speed of lead-car constant, car-following with speed of lead-car varying, speed judgments, lateral position steering error, speed production, and speed maintenance. It was found that subjects required about double the time gap to make a safe passing judgment at night than in the day, but no effect of alcohol was found. With the speed of a lead-car held constant, drivers under alcohol allowed a significantly greater headway than those of the placebo group. In addition, the variance in headway was significantly greater, both on the secondary road and the freeway, for the drinking drivers. When the speed of the lead-car was purposely varied in car-following, the mean headway and the variance in headway were significantly greater during the daytime than at night. In a limited set of the conditions there was also a significantly greater variance in headway attributable to alcohol. When subjects were requested to maintain the car at a fixed 80km/h over 11.3 km, with the speedometer covered, there was a significantly greater variance in speed for the alcohol group than the placebo group. There were no significant effects of alcohol found in: judgments of the speed of overtaking vehicles, lateral position deviations in steering, speed production without the use of the speedometer and the minimum safe time judged to be required to pass a vehicle ahead of them.

An adaptive time gap car-following model

2010 ◽  
Vol 44 (8-9) ◽  
pp. 1115-1131 ◽  
Author(s):  
Antoine Tordeux ◽  
Sylvain Lassarre ◽  
Michel Roussignol
Keyword(s):  
Car Following ◽  
Car Following Model ◽  
Adaptive Time ◽  
Time Gap

Time Block After Time Block

ASHA Leader ◽  
2013 ◽  
Vol 18 (8) ◽  
pp. 40-45 ◽  
Author(s):  
Judy Rudebusch ◽  
JoAnn Wiechmann
Keyword(s):  
Full Range ◽  
Time Block ◽  
School Based ◽  
Schedule Activity

To offer a full range of RTI and IEP services, school-based SLPs can schedule activity blocks rather than go student by student—here's how.

The Use of Neuroplastic Principles Affects the Swallow Motor Plan of a Patient in Severe Cognitive Decline: A Case Study

2016 ◽  
Vol 1 (15) ◽  
pp. 79-83
Author(s):  
Ed Bice ◽  
Kristine E. Galek
Keyword(s):  
Central Nervous System ◽  
Cognitive Decline ◽  
Full Range ◽  
Movement Speed ◽  
Positive Outcomes ◽  
Verbal Cues ◽  
Motor Plan ◽  
Bolus Size ◽  
The Central Nervous System

Dysphagia is common in patients with dementia. Dysphagia occurs as a result of changes in the sensory and motor function of the swallow (Easterling, 2007). It is known that the central nervous system can undergo experience-dependent plasticity, even in those individuals with dementia (Park & Bischof, 2013). The purpose of this study was to explore whether or not the use of neuroplastic principles would improve the swallow motor plan and produce positive outcomes of a patient in severe cognitive decline. The disordered swallow motor plan was manipulated by focusing on a neuroplastic principles of frequency (repetition), velocity of movement (speed of presentation), reversibility (Use it or Lose it), specificity and adaptation, intensity (bolus size), and salience (Crary & Carnaby-Mann, 2008). After five therapeutic sessions, the patient progressed from holding solids in her mouth with decreased swallow initiation to independently consuming a regular diet with full range of liquids with no oral retention and no verbal cues.

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