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Vehicular Technology, IEEE Transactions on

Issue 8 • Date Oct. 2009

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Displaying Results 1 - 25 of 84
  • Table of contents

    Page(s): C1 - C4
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    Freely Available from IEEE
  • IEEE Transactions on Vehicular Technology publication information

    Page(s): C2
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    Freely Available from IEEE
  • Special Section on Vehicular Energy-Storage Systems

    Page(s): 3879 - 3881
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    Freely Available from IEEE
  • Influence of Battery/Ultracapacitor Energy-Storage Sizing on Battery Lifetime in a Fuel Cell Hybrid Electric Vehicle

    Page(s): 3882 - 3891
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1209 KB) |  | HTML iconHTML  

    Combining high-energy-density batteries and high-power-density ultracapacitors in fuel cell hybrid electric vehicles (FCHEVs) results in a high-performance, highly efficient, low-size, and light system. Often, the battery is rated with respect to its energy requirement to reduce its volume and mass. This does not prevent deep discharges of the battery, which are critical to the lifetime of the battery. In this paper, the ratings of the battery and ultracapacitors are investigated. Comparisons of the system volume, the system mass, and the lifetime of the battery due to the rating of the energy storage devices are presented. It is concluded that not only should the energy storage devices of a FCHEV be sized by their power and energy requirements, but the battery lifetime should also be considered. Two energy-management strategies, which sufficiently divide the load power between the fuel cell stack, the battery, and the ultracapacitors, are proposed. A charging strategy, which charges the energy-storage devices due to the conditions of the FCHEV, is also proposed. The analysis provides recommendations on the design of the battery and the ultracapacitor energy-storage systems for FCHEVs. View full abstract»

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  • Comparative Study of Fuel-Cell Vehicle Hybridization with Battery or Supercapacitor Storage Device

    Page(s): 3892 - 3904
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    This paper studies the impact of fuel-cell (FC) performance and control strategies on the benefits of hybridization. One of the main weak points of the FC is slow dynamics dominated by a temperature and fuel-delivery system (pumps, valves, and, in some cases, a hydrogen reformer). As a result, fast load demand will cause a high voltage drop in a short time, which is recognized as a fuel-starvation phenomenon. Therefore, to employ an FC in vehicle applications, the electrical system must have at least an auxiliary power source to improve system performance when electrical loads demand high energy in a short time. The possibilities of using a supercapacitor or a battery bank as an auxiliary source with an FC main source are presented in detail. The studies of two hybrid power systems for vehicle applications, i.e., FC/battery and FC/supercapacitor hybrid power sources, are explained. Experimental results with small-scale devices (a polymer electrolyte membrane FC of 500 W, 40 A, and 13 V; a lead-acid battery module of 33 Ah and 48 V; and a supercapacitor module of 292 F, 500 A, and 30 V) in a laboratory authenticate that energy-storage devices can assist the FC to meet the vehicle power demand and help achieve better performance, as well as to substantiate the excellent control schemes during motor-drive cycles. View full abstract»

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  • New Battery Model and State-of-Health Determination Through Subspace Parameter Estimation and State-Observer Techniques

    Page(s): 3905 - 3916
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    This paper describes a novel adaptive battery model based on a remapped variant of the well-known Randles' lead-acid model. Remapping of the model is shown to allow improved modeling capabilities and accurate estimates of dynamic circuit parameters when used with subspace parameter-estimation techniques. The performance of the proposed methodology is demonstrated by application to batteries for an all-electric personal rapid transit vehicle from the urban light transport (ULTRA) program, which is designated for use at Heathrow Airport, U.K. The advantages of the proposed model over the Randles' circuit are demonstrated by comparisons with alternative observer/estimator techniques, such as the basic Utkin observer and the Kalman estimator. These techniques correctly identify and converge on voltages associated with the battery state-of-charge (SoC), despite erroneous initial conditions, thereby overcoming problems attributed to SoC drift (incurred by Coulomb-counting methods due to overcharging or ambient temperature fluctuations). Observation of these voltages, as well as online monitoring of the degradation of the estimated dynamic model parameters, allows battery aging (state-of-health) to also be assessed and, thereby, cell failure to be predicted. Due to the adaptive nature of the proposed algorithms, the techniques are suitable for applications over a wide range of operating environments, including large ambient temperature variations. Moreover, alternative battery topologies may also be accommodated by the automatic adjustment of the underlying state-space models used in both the parameter-estimation and observer/estimator stages. View full abstract»

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  • Impact of Calendar Life and Cycling Ageing on Supercapacitor Performance

    Page(s): 3917 - 3929
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    Supercapacitors (SCs), which are also known as ultracapacitors, are commonly based on porous activated carbon electrodes and electrostatic charge-storage mechanisms. Carbon electrodes are supposed to be chemically and electrochemically inert, and the electrostatic nature of the charge-storage mechanism is highly reversible. These properties should assure that SCs have an infinite shelf life. However, in practice, SC cells exhibit performance fading when they are used for months. The purpose of this paper is to compare the performance fading of SCs in two types of tests. The first accelerated test is the calendar life test, which evaluates cell degradation when cells are used at elevated voltages and temperatures; these degradations are observed in cells during rest periods. The second test is the power cycling test, which corresponds to degradations during the actual use of SCs as peak power sources in hybrid electric applications. In this paper, we use an impedance model to monitor changes in cell behavior. This analytical impedance model is based not only on physical quantities, such as double-layer capacitance, specific area, and electrolyte conductivity, but on elementary electrode dispersion as well. This model is validated in the frequency domain using the initial state of the tested SC for different temperature and voltage configurations. Then, we present and specify two types of tests. A periodic characterization based on impedance spectroscopy is done to quantify impedance changes during the ageing tests. The obtained results confirm that the impedance real part is increasing and that the capacitance is decreasing during the two ageing tests; however, the way they change is different. Indeed, the shape of the impedance real part is conserved in the calendar life test, whereas it is distorted in the power cycling test. This difference will be explained in terms of the evolution of the impedance model parameters. This paper confirms that the two ageing tests - - affect the SC performances differently. View full abstract»

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  • Impedance Observer for a Li-Ion Battery Using Kalman Filter

    Page(s): 3930 - 3937
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    Most methods for state-of-charge or state-of-health prognostics are impedance based. Impedance models must be as simple as possible to be implemented on embedded applications but as accurate as possible to represent the main electrochemical phenomena. The parameters of such models can be identified using impedance spectroscopy. However, the electrochemical features change in relation to numerous parameters, such as temperature or aging, which involves updating the model of the battery online. This paper deals with the use of an extended Kalman filter (EKF) for the observation of the parameters of a Li-ion battery lumped model. First, this paper will focus on the electrical model that can be used to represent the main electrochemical phenomena in the battery. Then, mathematical considerations about the EKF are reminded to be applied to the observation of the impedance parameters of the battery. This method has been validated on an urban driving cycle of a hybrid electric vehicle. View full abstract»

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  • Feasibility Analysis of a Novel Cell Equalizer Topology for Plug-In Hybrid Electric Vehicle Energy-Storage Systems

    Page(s): 3938 - 3946
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    To meet the stringent cost targets for hybrid electric, plug-in hybrid electric (PHEV), and all-electric vehicles, serious improvement in battery cycle life and safety is undoubtedly essential. More recently, lithium batteries, in the form of lithium-ion, lithium-polymer, or lithium iron phosphate, have profoundly been explored. Despite critical research initiatives, lithium-based batteries have not yet been able to meet the steep energy demands, long lifetime, and low cost, which are unique to vehicular-propulsion applications. One of the most practical techniques of improving overall performance is to use suitable power electronics intensive cell-voltage equalizers in conjunction with onboard energy-storage devices. There have been some interesting developments in this area during the last few years, but cost constraints and high current specifications have prevented the complete deployment of this versatile technology. The purpose of this paper is to introduce a novel configuration for a cell-voltage equalizer, with the potential of fulfilling the expectations of low cost, high current capability, and high efficiency. A comprehensive comparison between the theoretical novel equalizer, a typical equalizer, and the experimental prototype of the novel equalizer will be presented, which will help analyze performance, complexity, and cost. View full abstract»

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  • Sizing and Energy Management of a Hybrid Locomotive Based on Flywheel and Accumulators

    Page(s): 3947 - 3958
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    The French National Railways Company (SNCF) is interested in the design of a hybrid locomotive based on various storage devices (accumulator, flywheel, and ultracapacitor) and fed by a diesel generator. This paper particularly deals with the integration of a flywheel device as a storage element with a reduced-power diesel generator and accumulators on the hybrid locomotive. First, a power flow model of energy-storage elements (flywheel and accumulator) is developed to achieve the design of the whole traction system. Then, two energy-management strategies based on a frequency approach are proposed. The first strategy led us to a bad exploitation of the flywheel, whereas the second strategy provides an optimal sizing of the storage device. Finally, a comparative study of the proposed structure with a flywheel and the existing structure of the locomotive (diesel generator, accumulators, and ultracapacitors) is presented. View full abstract»

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  • Performance Comparison of Three Storage Systems for Mild HEVs Using PHIL Simulation

    Page(s): 3959 - 3969
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    Hybrid electric vehicles (HEVs) would contribute to energy saving and greenhouse effect reduction if they were to be massively launched on the market. A notable effort has been done in simulation to optimize energy consumption and component sizing. Power-hardware-in-the-loop (PHIL) simulation could be a further step to obtain more realistic performance and to compare different solutions, including economic aspects. This paper deals with the implementation on a high dynamic test bench of a diesel mild parallel HEV using the PHIL technique. Three configurations, corresponding to different energy-storage systems, have been tested under the same conditions. Power, energy, consumption, and pollutant emission performance, which are measured on the test bench, are compared and discussed. View full abstract»

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  • Advanced Integrated Bidirectional AC/DC and DC/DC Converter for Plug-In Hybrid Electric Vehicles

    Page(s): 3970 - 3980
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    Hybrid electric vehicle (HEV) technology provides an effective solution for achieving higher fuel economy, better performance, and lower emissions, compared with conventional vehicles. Plug-in HEVs (PHEVs) are HEVs with plug-in capabilities and provide a more all-electric range; hence, PHEVs improve fuel economy and reduce emissions even more. PHEVs have a battery pack of high energy density and can run solely on electric power for a given range. The battery pack can be recharged by a neighborhood outlet. In this paper, a novel integrated bidirectional AC/DC charger and DC/DC converter (henceforth, the integrated converter) for PHEVs and hybrid/plug-in-hybrid conversions is proposed. The integrated converter is able to function as an AC/DC battery charger and to transfer electrical energy between the battery pack and the high-voltage bus of the electric traction system. It is shown that the integrated converter has a reduced number of high-current inductors and current transducers and has provided fault-current tolerance in PHEV conversion. View full abstract»

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  • Dynamic Voltage Equalization for Series-Connected Ultracapacitors in EV/HEV Applications

    Page(s): 3981 - 3987
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    Energy-storage systems (ESSs) play an important role in electric vehicle (EV) and hybrid EV (HEV) applications. In the system, an ultracapacitor is preferred for high power buffer and regenerative braking energy storage because it has the advantages of high power density, long life cycles, and high efficiency. While in the high-voltage application, the ultracapacitors are employed in series, and the voltage unbalance issue must be taken care of. This paper presents a novel circuit for equalizing a series ultracapacitor stack, which is based on a dc-dc converter. The proposed voltage-equalization circuit derives energy from the series ultracapacitor stack and transfers them to the weakest ultracapacitor cell. The equalizer balances the whole stack by sequentially compensating the weak ultracapacitor cells. Unlike previous methods for battery-storage systems, which include complex circuit detecting and comparing the voltages of capacitor cells, the novel equalizer can realize autonomic voltage equalization without voltage detection and comparison, and it is more efficient with the soft switching method, which is a benefit for high-power applications in EV/HEV. The simulation and experiment results validate the feasibility of the proposed equalization circuits. View full abstract»

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  • Unified Laguerre Polynomial-Series-Based Distribution of Small-Scale Fading Envelopes

    Page(s): 3988 - 3999
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    We derive new unified probability density function (pdf) formulas based on the generalized Laguerre polynomial series expansion that cover a wide range of small-scale fading distributions in wireless communications. The unified envelope pdf covers many known Laguerre polynomial-series-based pdf's and small-scale fading distributions, which include the multiple-waves-plus-diffuse-power (MWDP) fading, kappa-mu, Nakagami-m, Rician (Nakagami-n), Nakagami-q (Hoyt), Rayleigh, Weibull, and alpha-mu (Stacy) distributions as special cases. We highlight that the unified pdf formulas are general and applicable to characterize the distribution of any random variable defined on the positive range. We then propose two truncated forms of the pdf and prove that the original pdf and both truncated forms satisfy the properties of a valid pdf. A new cumulative distribution function and a moment-generating function of this pdf are derived. We also analyze the truncation error for the case when only a finite number of terms are kept in the series expansion. View full abstract»

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  • Ricean K -Factors in Narrow-Band Fixed Wireless Channels: Theory, Experiments, and Statistical Models

    Page(s): 4000 - 4012
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    Fixed wireless channels in suburban macrocells are subject to fading due to scattering by moving objects such as windblown trees and foliage in the environment. When, as is often the case, the fading follows a Ricean distribution, the first-order statistics of fading are completely described by the corresponding average path gain and Ricean K-factor. Because such fading has important implications for the design of both narrow-band and wideband multipoint communication systems that are deployed in such environments, it must be well characterized. We conducted a set of 1.9-GHz experiments in suburban macrocell environments to generate a collective database from which we could construct a simple model for the probability distribution of K as experienced by fixed wireless users. Specifically, we find K to be lognormal, with the median being a simple function of season, antenna height, antenna beamwidth, and distance and with a standard deviation of 8 dB. We also present plausible physical arguments to explain these observations, elaborate on the variability of K with time, frequency, and location, and show the strong influence of wind conditions on K. View full abstract»

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  • Fade Slope Analysis of Ka-Band Earth-LEO Satellite Links Using a Synthetic Rain Field Model

    Page(s): 4013 - 4022
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    Because the motion of a low Earth orbit (LEO) satellite across the sky causes the Earth-space path to very quickly pass through any rain cells in the vicinity, the degree of rain fading on such paths changes more rapidly and leads to steeper fade slopes than in the geostationary case. Because comprehensive measurement data have not yet been compiled for fading on LEO links in the Ka-band, we have used simulations based on Goldhirsh's method for determining the key parameters of the well-known EXCELL model of a horizontal rain structure from long-term global rain statistics to obtain plausible estimates of the fade slope distributions for selected scenarios. The results that we obtained for geostationary satellites closely match those observed at selected sites during the Advanced Communications Technology Satellite program. The results that we obtained for LEO satellites show how fade slopes will steepen as 1) the altitude of the satellite decreases; 2) the frequency band of operation increases; and 3) the average rain rate increases. Furthermore, they suggest that, at a given probability level, the fade slopes could be between two and ten times greater than those for geostationary satellites and that mobile terminals with a clear view of the sky will experience fade slopes that are similar to those encountered by fixed or transportable terminals. These results have important implications for the design of power control algorithms and other fade-mitigation techniques. View full abstract»

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  • The Effects of Tropical Weather on Radio-Wave Propagation Over Foliage Channel

    Page(s): 4023 - 4030
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    This paper investigates the dynamic property of a tropical forested channel due to the weather effect on very high frequency (VHF) and ultrahigh frequency (UHF) radio-wave propagation. In this paper, continuous-wave (CW) envelope fading waveforms are recorded over a period of 50 s with static antennas. This paper focuses on the analysis of the combined effect of wind and rain, which is often encountered in a tropical forest. The induced temporal effects are discussed and compared with theoretical models. It is found that the distribution of temporal fading components resembles a Rician distribution function. Its Rician K factor gradually decreases as the strength of either wind or rain increases due to the movement of the forest components. View full abstract»

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  • Radio Channel Characterization for Moderate Antenna Heights in Forest Areas

    Page(s): 4031 - 4035
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    This paper describes the results achieved by an experimental campaign whose goal was to characterize the directional propagation channel at 1.9 GHz in forested areas for moderate antenna heights. These experimental results are useful in the context of pedestrian radio-localization systems relying on cellphone signals. Wideband experimental results, which are recorded with transmit-to-receive distances ranging from 40 to 110 m, indicate that the path loss is well modeled by ITU-R Recommendation 833-4. The temporal fading and multipath dispersion are also analyzed. The delay spread, which ranges from 60 to 120 ns, is strongly anticorrelated with the temporal coherence and increases with transmit-to-receive distance. The azimuth spread remains limited, with average values of about 15deg. View full abstract»

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  • Accurate Estimation of Correlation and Capacity for Hybrid Spatial-Angular MIMO Systems

    Page(s): 4036 - 4045
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    In this paper, several novel functions for accurately estimating the correlation and the multiple-input-multiple-output (MIMO) capacity of combined spatial and true polarization diversity (TPD) schemes are proposed for the first time. Minimum error estimation of the correlation for a hybrid spatial-TPD linear scheme previously reported cannot be obtained by simple nonlinear least-square estimators, and the use of genetic algorithms (GAs) provides an accurate solution. Channel matrix coefficients and MIMO capacities are analyzed for the diverse optimization strategies employed, which aim to identify the best prediction of MIMO performance. The novel functions are used with previously reported results and validated for Rayleigh fading scenarios with isotropic scattering using a multimode-stirred chamber (MIMO Analyzer). An accurate prediction of high correlation values is concluded to be of extreme importance for the final MIMO performance estimation. This has been found to be particularly important for estimating MIMO capacity with achieved prediction accuracies of 1.1% at SNR = 15 dB. In contrast, the accurate prediction of low correlation values has been found to have a less-important effect on the final capacity-predicting performance. View full abstract»

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  • Analysis and Implementation of a Time-Interleaved ADC Array for a Software-Defined UWB Receiver

    Page(s): 4046 - 4063
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    A software-defined radio (SDR) for ultrawideband (UWB) communication systems places several stringent requirements on the analog-to-digital converter (ADC). One alternative to using a single ADC is to sample the received signal with an array of lower speed ADCs that were driven by interleaved sampling clocks; however, mismatches among the ADCs will result in signal distortion. This paper makes three important contributions to overcoming this problem: 1) analytical quantification of the impact of ADC gain, offset, and timing mismatches on the performance of a time-interleaved sampling ADC array for UWB signals; 2) demonstration of the efficacy of using a pilot-based matched-filter architecture to mitigate the impact of timing mismatches in the presence of multipath; and 3) implementation of an 8-ADC time-interleaved UWB SDR testbed that operates at an effective sampling frequency of 6.4 GHz. In addition, our findings allow for the design specification of the number of pilots required to obtain a desired system performance. The simulation and measured performance results from this paper demonstrate that ADC mismatches can be controlled to within plusmn10%, yielding acceptable levels of distortion and bit-error-rate (BER) performance on the UWB SDR testbed. Both analytical and simulation results also demonstrate the efficacy of a pilot-based matched filter in mitigating the impact of timing mismatch errors, even in the presence of multipath. View full abstract»

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  • 3-D-Skeleton-Based Head Detection and Tracking Using Range Images

    Page(s): 4064 - 4077
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    Vision-based 3-D head detection and tracking systems have been studied in several applications like video surveillance, face-detection systems, and occupant posture analysis. In this paper, we present the development of a topology-based framework using a 3-D skeletal model for the robust detection and tracking of a vehicle occupant's head position from low-resolution range image data for a passive safety system. Unlike previous approaches to head detection, the proposed approach explores the topology information of a scene to detect the position of the head. Among the different available topology representations, the Reeb graph technique is chosen and is adapted to low-resolution 3-D range images. Invariance of the graph under rotations is achieved by using a Morse radial distance function. To cope with the particular challenges such as the noise and the large variations in the density of the data, a voxel neighborhood connectivity notion is proposed. A multiple-hypothesis tracker (MHT) with nearest-neighbor data association and Kalman filter prediction is applied on the endpoints of the Reeb graph to select and filter the correct head candidate out of Reeb graph endpoints. A systematic evaluation of the head detection framework is carried out on full-scale experimental 3-D range images and compared with the ground truth. It is shown that the Reeb graph topology algorithm developed herein allows the correct detection of the head of the occupant with only two head candidates as input to the MHT. Results of the experiments demonstrate that the proposed framework is robust under the large variations of the scene. The processing requirements of the proposed approach are discussed. It is shown that the number of operations is rather low and that real-time processing requirements can be met with the proposed method. View full abstract»

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  • A Vehicle Roll-Stability Indicator Incorporating Roll-Center Movements

    Page(s): 4078 - 4087
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    In the development of active-passive roll control systems, a vehicle model that can represent realistic roll behavior is essential for predicting the impending rollover and for accurately applying the control force to avoid vehicle rollover. The vehicle roll center is a key parameter that influences the vehicle roll dynamics. Since the roll center movement becomes important as the vehicle roll angle increases, it is desirable to include this effect in the roll control system. This paper proposes a dynamic roll stability indicator (RSI) incorporating roll center movement that generates rollover threshold in terms of lateral acceleration. A robust parameter identification algorithm using a disturbance observer is designed to estimate the lateral and vertical roll center movements. These estimates are later used in the RSI to update the rollover threshold. The effectiveness of the proposed method is demonstrated through simulations, and its performance is compared with other rollover warning algorithms. View full abstract»

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  • ANTS: Efficient Vehicle Locating Based on Ant Search in ShanghaiGrid

    Page(s): 4088 - 4097
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    Intelligent transportation systems (ITSs) have become increasingly important for public transportation in Shanghai, China. In response, ShanghaiGrid (SG) aims to provide abundant intelligent transportation services to improve traffic conditions. A fundamental service in SG is to locate the nearest desirable vehicles for users. In this paper, we propose an innovative protocol called ANTS to locate a desirable vehicle close to the querying user. The protocol finely mimics the efficient searching strategy adopted by a lost ant searching for its nest. Taking query locality into account, ANTS can retrieve the closest vehicles satisfying the query with high probability but incurs small query latency and modest network traffic. ANTS is a fully distributed and robust protocol and, therefore, has good scalability. Extensive simulations based on the real road network and the trace data of vehicle movements in Shanghai demonstrate the efficacy of ANTS. View full abstract»

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  • Adaptive Vehicle Lateral-Plane Motion Control Using Optimal Tire Friction Forces With Saturation Limits Consideration

    Page(s): 4098 - 4107
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    This paper presents an adaptive nonlinear control scheme aimed at the improvement of the handling properties of vehicles. The control inputs for steering intervention are the steering angle and wheel torque for each wheel, i.e., two control inputs for each wheel. The control laws are obtained from a nonlinear 7-degree-of-freedom (DOF) vehicle model. A main loop and eight cascade loops are the basic components of the integrated control system. In the main loop, tire friction forces are manipulated with the aim of canceling the nonlinearities in a way that the error dynamics of the feedback linearized system has sufficient degrees of exponential stability; meanwhile, the saturation limits of tires and the bandwidth of the actuators in the inner loops are taken into account. A modified inverse tire model is constructed to transform the desired tire friction forces to the desired wheel slip and sideslip angle. In the next step, these desired values, which are considered as setpoints, are tackled through the use of the inner loops with guaranteed tracking performance. The vehicle mass and mass moment of inertia, as unknown parameters, are estimated through parameter adaptation laws. The stability and error convergence of the integrated control system in the presence of the uncertain parameters, which is a very essential feature for the active safety means, is guaranteed by utilizing a Lyapunov function. Computer simulations, using a nonlinear 14-DOF vehicle model, are provided to demonstrate the desired tracking performance of the proposed control approach. View full abstract»

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  • Current Sensing for Automotive Electronics—A Survey

    Page(s): 4108 - 4119
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    Current sensing is widely used in power electronic applications such as dc-dc power converters and adjustable-speed motor drives. Such power converters are the basic building blocks of drivetrains in electric, hybrid, and plug-in hybrid electric vehicles. The performance and control of such vehicles depend on the accuracy, bandwidth, and efficiency of its sensors. Various current-sensing techniques based on different physical effects such as Faraday's induction law, Ohm's law, Lorentz force law, the magnetoresistance effect, and the magnetic saturation effect are described in this paper. Each technique is reviewed and examined. The current measurement methods are compared and analyzed based on their losslessness, simplicity, and ease of implementation. View full abstract»

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Aims & Scope

IEEE Transactions on Vehicular Technology covers land, airborne, and maritime mobile services, vehicular electrotechnology, equipment, and systems identified with the automotive industry.

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Meet Our Editors

Editor-in-Chief
Yuguang Michael Fang
University of Florida