Varying Vehicle Speed Research Articles

Research into the problem of wear creating a polygon-shaped wheel on metro trains

The reasons for wear of a wheel to create a polygon-shaped wheel on metro trains are analysed in this paper. Analysis of wear data leads to the conclusion that it is mainly structural vibration of the wheelset that causes the wear that creates polygon-shaped wheels. After analysing the characteristics of the structure and vibration of the vehicle, a model that considers wheelset flexibility is established. We then analyse the effects of flexible deformation of the wheelset on vertical force, creepage and creep force in wheel/rail rolling contact, and find that the main wheel wear frequency is 35.98 Hz. As for the question of how many faces the worn polygon-shaped wheel displays, we propose that the nature of the wear to create the polygon-shaped wheel depends on the average running speed of the vehicle. This relationship accounts for the apparent contradiction of a fixed vibration frequency and variable vehicle speed leading to wear to create a polygon-shaped wheel, and shows how a multi-faced polygon can be caused by a low-frequency vibration between wheel and rail.

Predicting Truck Load Variation Using Q-Truck Model

The study of heavy vehicle forces on pavement is important for both vehicle and pavement. Indeed it was identified several factors such as environment, materials and design consideration affects pavement damage over time with traffic loads playing a key role in deterioration. Therefore, this paper presents dynamically varying tire pavement interaction load, thus enable to assess the strain response of pavements influenced by road roughness, truck suspension system, variation of axle loading and vehicle speed. A 100m pavement with good evenness was simulated to check the sensitivity of the dynamic loads and heavy truck vertical motions to the roughness. The most important performance indicators that are required in pavement distress evaluation are radial strain at the bottom of the asphalt concrete and vertical strain at the subgrade surface was predicted using peak influence function approach. The results show that truck speed is the most important variables that interact with truck suspension system and thus effect of loading time are extremely important when calculating the critical.

Research and modeling of the lane-changing behavior on the approach

In order to analyze the lane-changing behavior on the upstream of the intersections, based on the cellular automata traffic theory, a comprehensive lane-changing model for the traffic flow near the approach is proposed by combining the improved mandatory lane-changing model and discretionary lane-changing model. And the charts describing the scenarios of the space-time and traffic density for the traffic flow near the approach are obtained through simulation based on the comprehensive lane-changing model. Results show that the lane-changing rate at the approach is higher when the traffic density is in the ranges of [0, 0.2] and [0.4, 0.6]. The average vehicle speed is gradually reduced as lane-changing rate increases under median low vehicle stream density, but the variation of vehicle speed with lane-changing rate is not significant under high vehicle stream density.

Raised Crosswalks And Their Design Features InTraffic Calming

A road hump, or speed hump, is a traffic calming device used to reduce vehicle speed and volume on residential streets. Road humps are placed across the road to slow traffic and are often installed in a series of several humps in order to prevent cars from speeding before and after the hump. Speed humps are used in locations where very low speeds are desired and reasonable. Speed humps are typically placed on residential roads and are not used on major roads, bus routes, or primary emergency response routes. In Italy, the road humps are often built in the shape of raised crosswalks (RCWs) and they are generally placed both close and between intersections. This paper deals with the analysis of observed data on a sample of RCWs located in Tuscany, central Italy. Such data were referred both to geometry characteristics of the single raised crosswalk and recorded differences in vehicle speeds before and after it. Speed data were gathered using two automatic radarrecorders for each one of the sampled raised crosswalks. All the collected data were analysed firstly through statistical tests in order to assess their homogeneity or not between different locations and various types of roads; secondly, through modelling software to obtain a generally valid formulation to evaluate the functionality of the device. Finally, we were able to make some conclusions and highlight design aspects. On the one side, RCWs with similar geometries have similar effects on the lowering of vehicle speeds, regardless of local conditions (location, road geometry, driver behaviour, etc.). Moreover, recent developments of the research show that raised crosswalks installed in a series have an influence on the speed reduction in function of their number and their distance. On the opposite side, the effects of raised crosswalks with smaller heights (less than 6 cm) show clearly a very low influence on vehicle speed variations.

HEMU 430-X 주행특성을 고려한 호남고속철도 곡선궤도구조의 거동연구

The wheel-rail interaction forces are influenced by the velocity of vehicle, wheel load, alignment (curve radius, cant etc). For the safety of track structure, it is required to evaluate the influences for track and influential factors. Recently, the HEMU 430-X, which was developed by Next Generation High-Speed Rail Development R&D Project, achieved 421.4km/h in a test run of Daegu-Busan section of the Gyeongbu high speed rail on March in 2013. In the case of additional speed-up test on Test-Bed Section(Gongju-Jeongeup: KP 100~128km Osong starting point), the analysis of track forces is required for outer rail by the increase of dynamic force and centrifugal force of vehicle. In this paper, the vehicle speed variation on HSL line is evaluated by TPS analysis considering the tractive effort of HEMU 430-X, tested running resistance and alignment of Honam HSR. And the track forces are evaluated by centrifugal force and impact factor on curved track.

PERFORMANCE EVALUATION OF PROBABILISTIC RELAY IN AD HOC ON-DEMAND DISTANCE VECTOR AND AD HOC ON-DEMAND MULTIPATH DISTANCE VECTOR UNDER HIGHLY DYNAMIC ENVIRONMENTS

Vehicular Ad hoc Networks (VANETs) are a specific class of Mobile Ad hoc Networks (MANETs). Since vehicles tend to move in a high speed, the network topology is rapidly changed. Thus vehicle’s connectivity problem is one of the interesting issues in VANETs. Ad hoc On-demand Multipath Distance Vector (AOMDV) is an extended version of ad hoc on-demand distance vector (AODV). AOMDV is designed to overcome a connectivity problem due to highly dynamic network topology. It provides multipath for data packets delivery from the source to the destination. However, AOMDV’s multipath establishment and maintenance generate more control packets than those of AODV’s unipath. Meanwhile, both protocols degrade their performance when the vehicle speed is increasing. Thus in this study, we added probabilistic relay, which enables adjacent vehicles to probabilistically relay unsuccessful data packet transmission into IEEE 802.11 as a MAC standard model and proposed AODV with Probabilistic Relay (AODV-PR) and AOMDV with Probabilistic Relay (AOMDV-PR). Based on our simulation results, the addition of probabilistic relay clearly helps those protocols to improve their performances especially in packet delivery ratio under highly dynamic environments. Probabilistic relay adds the number of generated beacon messages, but does not produce any additional routing messages. We evaluate those protocol performances based on several metrics such as packet delivery ratio, routing overhead, average delivery delay, hop count and number of relays under variation of vehicle speed and beacon interval. We show that beacon interval has a huge influence in the performance of AODV-PR and AOMDV-PR especially for their routing overhead.

Development of a methodology to demonstrate the environmental impact of connected vehicles under lane-changing conditions

This paper describes a lane-change model for connected vehicles, and evaluates the environmental impact per road level of service (LOS) when a host vehicle makes a lane change. During manual driving, the host vehicle accelerates or decelerates to create a safe distance before the vehicle makes a lane change. During automated driving, however, the host vehicle makes lane changes in response to the acceleration or deceleration of the vehicle in front of it through vehicle-to-vehicle communications. The gap, safe distance, and variation in vehicle speed depending on the LOS are analyzed using simulation for both automated and manual driving. For lane changing from a faster to a slower lane, the reduction in CO2 emissions of the connected vehicle was in the range 4770–54,291 g/km in comparison to the manual vehicle. For lane changing from a slower to a faster lane, the CO2 reductions were in the range 40,788–91,884 g/km. In more complex traffic situations, the CO2 reductions of the connected vehicles were larger than in simple traffic situations. This study indicates that the use of connected vehicles can result in a reduction of CO2 emissions.

A Decision Support System for the Operation of Vending Machine Supply Chains with Product Substitution and Varying Vehicle Speed

This paper presents a decision support system for the operation of general and smart vending machine supply chains with product substitution and varying vehicle speeds. The system supports various functions such as the determination of operation parameters, supply chain performance evaluation, CO2 analysis of delivery vehicle emissions, and more. The potential benefits of the system include the provision of guidance, solutions, and simulation environments for companies in the extensive operations of vending machine supply chains.

Understanding and Modeling the Human Driver Behavior Based on MPC

Better understanding driver behavior is essential for autonomous vehicles, as well as simulation, evaluation and optimization of a driver-vehicle closed-loop system. In this paper, the human driver behavior is first discussed in the form of perception, decision, and execution. In the following, the modelling of the driver behavior is proposed based on the preview-follower theory. The driver model includes three parts which are perception module, decision making module and execution module. The decision making module contains longitudinal control using proportional-integral-derivative (PID) controller and lateral control using model predictive control (MPC) method. Moreover, the response of muscle and nerve is modelled in the form of execution module. Typical simulations are carried out using vehicle dynamics software veDYNA and indicate that the proposed driver model is suitable for representative path following at varying vehicle speed.

Nodal disparity in opposite trusses of a steel bridge: a case study

This study presents the downstream and upstream truss behaviour of a through type newly constructed steel bridge. The modal parameter variation of truss joints of bridge with variable vehicle speed effects have been worked out to determine their flexibility. The testing on the steel bridge was carried out with the same instrument setup on upstream and downstream trusses of bridge subjected to three different speed of the same vehicle. The comparison of the changes in the frequency, mode shape, mode shape curvature and modal strain energy with respect to both the trusses and analytical model has been presented. It has been concluded that upstream and downstream truss of the bridge can behave in different manner even if designed for same loading due to constructional variations and the vehicle movement. The difficulty of modal parameter extraction of the particular bridge under study increased with the increase in speed due to decreased excitation time.

A Contribution to Research of Vibrational Loads of the Vehicle Steering System's Tie-Rod in Characteristic Exploitation Conditions

The paper presents and reviews the results of the analysis of vibrational loads of the steering system's tie-rod for passenger car in characteristic exploitation conditions. Experimental data are acquired using the left tie-rod's relative deformation sensor, vertical acceleration sensors at the centres of all four wheels, vertical acceleration sensor at the connecting point between the left front shock absorber and the vehicle body, longitudinal vehicle speed sensor, steering wheel angular displacement sensor and steering wheel torque sensor. Tests are performed during straight line drive and vehicle cornering, with constant and variable vehicle speed and on different types of the roads. On the basis of acquired experimental data, the influences of the inputs from the road roughness (type of the road), the steering wheel torque, the steering wheel angular displacements and vehicle speed on vibrational loads of the steering system's tie-rod loads are analyzed.

Modelling and simulation of gear synchronisation and shifting in dual-clutch transmission equipped powertrains

Dual-clutch transmissions have increased in prevalence through the combination of high efficiency and shift quality. This is achieved through the automation of conventional manual transmission synchronisers for gear selection with automated clutch-to-clutch shift control, minimising loss of traction to the road. This article derives a suitably detailed model of a dual-clutch transmission equipped powertrain for the transient simulation and analysis of combined synchroniser engagement and gear shifts. Models are derived for a powertrain equipped with a wet dual-clutch transmission with particular focus on a detailed synchroniser mechanism model, including speed synchronisation, ring unblocking and indexing stages of engagement. To demonstrate the combination of synchroniser engagement with clutch-to-clutch shifting, several simulations are conducted to study the variation of chamfer alignment, vehicle speed and synchroniser engagement timing on powertrain response. Results indicate that vehicle speed and chamfer alignment have only limited impact on the quality of shifting. Synchroniser timing can have a more significant influence on shift quality, stressing the need for independence of these processes.

An Investigation on the Effect of Driver Style and Driving Events on Energy Demand of a PHEV

Environmental concerns, security of fuel supply and CO2 regulations are driving innovation in the automotive industry towards electric and hybrid electric vehicles. The fuel economy and emission performance of hybrid electric vehicles (HEVs) strongly depends on the energy management system (EMS). Prior knowledge of driving information could be used to enhance the performance of a HEV. However, how the necessary information can be obtained to use in EMS optimisation still remains a challenge. In this paper the effect of driver style and driving events like city and highway driving on plug in hybrid electric vehicle (PHEV) energy demand is studied. Using real world driving data from three drivers of very different driver style, a simulation has been exercised for a given route having city and highway driving. Driver style and driving events both affect vehicle energy demand. In both driving events considered, vehicle energy demand is different due to driver styles. The major part of city driving is reactive driving influenced by external factors and driver leading to variation in vehicle speed and hence energy demand. In free highway driving, the driver choice of cruise speed is the only factor affecting vehicle energy demand.

Vehicle Speed Meters Validation and Verification System

Speed meters verification principles and problems are observed in the article. Method of vehicle average speed measurement over the specified length road segment was proposed, using four laser units. The method allows to avoid synchronization between measurements of speed meter under metrological test and reference system during verification procedure and therefore to avoid vehicle speed variation influence. Developed reference speed measurement system has expanded uncertainty less than ±0.3 km/h, including vehicle speed variation term. Ill. 3, bibl. 8 (in English; abstracts in English and Lithuanian).DOI: http://dx.doi.org/10.5755/j01.eee.119.3.1372

A method for real-time condition monitoring of haul roads based on Bayesian parameter estimation

Current haul road management techniques, such as routine, periodic and urgent maintenance have shortcomings in many complex haul road environments. Real-time road condition monitoring may significantly reduce maintenance costs, both to the road and to the vehicles. A recent idea is that vehicle on-board data collection systems could be used to monitor haul roads on a real-time basis by means of vibration signature analysis. This paper proposes a methodology based on Bayesian regression to isolate the effect of varying vehicle speed on the measured vehicle response metric. A key feature of the proposed methodology is that it avoids the costly need to generate analytical or empirical vehicle models.

Analysis on the Effect of Parameters Variation on Dynamic Stress Intensity Factor of Asphalt Overlay Reflective Crack

With dynamic stress intensity factor (DSIF) as a characteristic parameter, this paper makes an analysis on the effect of parameters variation of vehicle speed, asphalt overlay thickness, modulus and old cement concrete pavement joint width on asphalt overlay reflective crack by investigating the variation law of reflective crack of asphalt overlay structure suffer wheel load. The results show that: the maximum dynamic stress intensity factor decreases with the increase of speed. Numerical value of maximum dynamic stress intensity factor is larger than the corresponding value of the static load. The longer the initial crack, the less the times of sustaining load of the same extending length. The increase of asphalt overlay thickness can reduce the value of dynamic stress intensity factor to a certain extent. With the augmentation of asphalt overlay modulus, the effect of dynamic load on reflective crack can be reduced in some degree. Dynamic stress intensity factor increases with the increase of joint width.

Dynamic Response Analysis of Stress Intensity Factors of Reflective Cracking in Asphalt Overlay Suffer Wheel Load

Partial wheel loading of the existing old cement concrete pavement joint will easily causes shear-type reflective cracking of asphalt overlay, which will cut down the service life of the pavement. This paper conducts an research on the changing rules of stress intensity factors of reflective cracking in asphalt overlay suffer dynamic loads. Choose 3 asphalt overlays with typical reflective cracking extend length of 1cm, 4cm and 8cm to investigate the impacts of parametric variation of vehicle speed, asphalt overlays thickness and modulus and stress absorbing layer on stress intensity factors of reflective cracking in asphalt overlays suffer singe-wheel dynamic loads. Results show that time history curves of dynamic stress intensity factors declines with the increase of structure-layer parameters; the maximum amplitude decreases as time goes on; the larger the structure parameter is, the faster the degradation is; and the vibration levels to gentle in the later half period, but stress intensity factors are not equal to zero in the last period of vibration, which shows that there exists residual stress intensity factors.

On the Information Propagation Process in Mobile Vehicular Ad Hoc Networks

In this paper, we study the information propagation process in a 1-D mobile ad hoc network formed by vehicles Poissonly distributed on a highway and traveling in the same direction at randomly distributed speeds that are independent between vehicles. Considering a model in which time is divided into time slots of equal length and each vehicle changes its speed at the beginning of each time slot, independent of its speed in other time slots, we derive analytical formulas for the fundamental properties of the information propagation process and the information propagation speed (IPS). Using the formulas, one can straightforwardly study the impact on the IPS of various parameters such as radio range, vehicular traffic density, and time variation of vehicle speed. The accuracy of the results is validated using simulations. The research provides useful guidelines on the design of vehicular ad hoc networks (VANETs).

Modelling mobility: A discrete revolution

We introduce a new approach to model and analyze mobility. It is fully based on discrete mathematics and yields a class of mobility models, called the Markov Trace model. It can be viewed as the discrete version of the Random Trip model: including all variants of the Random Way-Point model [15]. We derive fundamental properties and explicit analytical formulas for the stationary probability distributions yielded by the Markov Trace model. Besides having a per-se interest, such results can be exploited to compute formulas and properties for concrete cases by just applying counting arguments. We apply the above general results to the discrete version of the Manhattan Random Way-Point. We get explicit formulas for the total stationary distribution and for two important conditional distributions: the agent spatial and the agent destination ones. Our method makes the analysis of complex mobile systems a feasible task. As a further evidence of this important fact, we model a complex vehicular-mobile system over a set of crossing streets. Several concrete issues are implemented such as parking zones, traffic lights, and variable vehicle speeds. By using a modular version of the Markov Trace model, we get explicit formulas for the stationary distributions yielded by this vehicular-mobile model as well.

A methodology for the design of robust rollover prevention controllers for automotive vehicles using differential braking

In this paper we apply recent results from robust control to the problem of rollover prevention in automotive vehicles. Specifically, we exploit results which provide controllers to robustly guarantee that the peak values of the performance outputs of an uncertain system do not exceed certain values. As a measure of performance for rollover prevention, we use the Load Transfer Ratio (LTR) and design differential-braking-based rollover controllers to keep the value of this quantity below a certain level; we also obtain controllers which yield robustness to variations in vehicle speed. We present numerical simulations using a nonlinear multi-body vehicle simulation model to demonstrate the effectiveness of our controllers in preventing rollover.