A numerical method for the simulation of freight train emergency braking operations based on the UIC braked weight percentage

The present paper shows the development of a strategy for the calculation of the air brake forces of European freight trains. The model is built to upgrade the existing Politecnico di Torino longitudinal train dynamics(LTD) code LTDPoliTo, which was originally unable to account for air brake forces. The proposed model uses an empirical exponential function to calculate the air brake forces during the simulation, while the maximum normal force on the brake friction elements is calculated according to the indication of the vehicle braked weight percentage.Hence, the model does not require to simulate in detail the fluid dynamics in the brake pipe nor to precisely know the main parameters of the braking system mounted on each vehicle. The model parameters are tuned to minimize the difference between the braking distance computed by the LTDPoliTo code and the value prescribed by the UIC544-1 leaflet in emergency braking operations. Simulations are run for different configurations of freight train compositions including a variable number of Shimmns wagons trailed by an E402B locomotive at the head of the train, as suggested in a reference literature paper. The results of the proposed method are in good agreement with the target braking distances calculated according to the international rules.

Influence of Friction Drive Lift Gears Construction on the Length of Braking Distance

The friction drive elevators the influence of the braking distance has very high significance to meet certain safety regulations and comfort.During the emergency braking the delay for the system a frame and a cabin should be within the range from 0.2 to 9.81 m/s~2.However,there are no specialist literatures regarding the issues connected with emergency braking of elevating devices either.The results of the own empirical research work are presented regarding the influence of design changes on the working parameters of the friction drive elevator gears.ASG100,KB 160,PP16,PR2000UD and CHP2000 types of safety progressive gears are analyzed.ASG100,KB 160,PP16,PR2000UD type progressive gears are already produced by European manufacturers.CHP2000 type gears are established as the alternative option for the already existing solutions.The unique cam system has been used in the CHP 2000 gears.The cam leverage gives the chance to unblock,in a very easy way,the clamed gears after braking.Thus,it is a key aspect to perform laboratory tests over the braking process of a newly created solution.The proper value of the braking distance has a significant influence on the value of delay in terms of binding standards.The influence of loading on the effective braking distance and the value of the falling elevator cabin speed are analyzed and the results are presented.The results presented are interesting from lift devices operation and a new model of CHP 2000progressive gear point of view.

Overview of Vehicle AEB

With the rapid development of China's economy and the continuous improvement of people's living standards,people pay more attention to the safety of cars.China's car sales and ownership is also rising,but also led to a lot of traffic accidents.With the continuous promotion of intelligent,electric and networked automobiles,Autonomous Emergency Braking system has become the focus of automobile enterprises in the active safety of automobiles.The overall scheme of auto emergency braking includes information acquisition module,control module and execution module.This paper briefly introduces the application status of this field at home and abroad,and discusses the function and implementation method of each module respectively.

Revealing driver psychophysiological response to emergency braking in distracted driving based on field experiments

Purpose–The purpose of this paper is to characterize distracted driving by quantifying the response time and response intensity to an emergency stop using the driver’s physiological states.Design/methodology/approach–Field tests with 17 participants were conducted in the connected and automated vehicle test field.All participants were required to prioritize their primary driving tasks while a secondary nondriving task was asked to be executed.Demographic data,vehicle trajectory data and various physiological data were recorded through a biosignalsplux signal data acquisition toolkit,such as electrocardiograph for heart rate,electromyography for muscle strength,electrodermal activity for skin conductance and force-sensing resistor for braking pressure.Findings–This study quantified the psychophysiological responses of the driver who returns to the primary driving task from the secondary nondriving task when an emergency occurs.The results provided a prototype analysis of the time required for making a decision in the context of advanced driver assistance systems or for rebuilding the situational awareness in future automated vehicles when a driver’s take-over maneuver is needed.Originality/value–The hypothesis is that the secondary task will result in a higher mental workload and a prolonged reaction time.Therefore,the driver states in distracted driving are significantly different than in regular driving,the physiological signal improves measuring the brake response time and distraction levels and brake intensity can be expressed as functions of driver demographics.To the best of the authors’knowledge,this is the first study using psychophysiological measures to quantify a driver’s response to an emergency stop during distracted driving.

Development of test scenarios and bicyclist surrogate for the evaluation of bicyclist automatic emergency braking systems

Purpose–To support the standardized evaluation of bicyclist automatic emergency braking(AEB)systems,test scenarios,test procedures and test system hardware and software tools have been investigated and developed by the Transportation Active Safety Institute(TASI)at Indiana University-Purdue University Indianapolis.This paper aims to focus on the development of test scenarios and bicyclist surrogate for evaluating vehicle–bicyclist AEB systems.Design/methodology/approach–The harmonized general estimates system(GES)/FARS 2010-2011 crash data and TASI 110-car naturalistic driving data(NDD)are used to determine the crash geometries and environmental factors of crash scenarios including lighting conditions,vehicle speeds,bicyclist speeds,etc.A surrogate bicyclist including a bicycle rider and a bicycle surrogate is designed to match the visual and radar characteristics of bicyclists in the USA.A bicycle target is designed with both leg pedaling and wheel rotation to produce proper micro-Doppler features and generate realistic motion for camera-based AEB systems.Findings–Based on the analysis of the harmonized GES/FARS crash data,five crash scenarios are recommended for performance testing of bicyclist AEB systems.Combined with TASI 110-car naturalistic driving data,the crash environmental factors including lighting conditions,obscuring objects,vehicle speed and bicyclist speed are determined.The surrogate bicyclist was designed to represent the visual and radar characteristics of the real bicyclists in the USA.The height of the bicycle rider mannequin is 173 cm,representing the weighted height of 50th percentile US male and female adults.The size and shape of the surrogate bicycle were determined as 26-inch wheel and mountain/road bicycle frame,respectively.Both leg pedaling motion and wheel rotation are suggested to produce proper micro-Doppler features and support the camera-based AEB systems.Originality/value–The results have demonstrated that the developed scenarios,test procedures and bicyclist surrogate will provide effective objective methods and necessary hardware and software tools for the evaluation and validation of bicyclist AEB systems.This is crucial for the development of advanced driver assistance systems.