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991.
A cooperative control algorithm for an in-wheel motor and an electric booster brake is proposed to improve the stability of an in-wheel electric vehicle. The in-wheel system was modeled by dividing it into motor and mechanical parts, and the electric booster brake was modeled through tests. In addition, the response characteristics of the in-wheel system and the electric booster brake were compared through a frequency response analysis. In the cooperative control, the road friction coefficient was estimated using the wheel speed, motor torque, and braking torque of each wheel, and the torque limit of the wheel to the road was determined using the estimated road friction coefficient. Based on the estimated road friction coefficient and torque limit, a cooperative algorithm to control the motor and the electric booster brake was proposed to improve the stability of the in-wheel electric vehicle. The performance of the proposed cooperative control algorithm was evaluated through a hardware-in-the-loop simulation (HILS). Furthermore, to verify the performance of the proposed cooperative control algorithm, a test environment was constructed for the anti-lock braking system (ABS) hydraulic module hardware, and the performance of the cooperative control algorithm was compared with that of the ABS by means of a HILS test. 相似文献
992.
In contemporary times, Public–Private Partnership (PPP) in transport infrastructure has gained considerable attention in developing regions following its success in the developed countries. However, Sub-Saharan Africa (SSA) is among the developing regions with few transport PPP projects and among the regions with high number of failed projects. Meanwhile the region's transport infrastructure need far exceeds it current provision. This paper therefore aims to examine the project experiences (success and failure factors) of three highly profiled transport PPP projects, namely the Lekki toll road concession project (Nigeria), N4 toll road (South Africa/Mozambique) and Port of Maputo (Mozambique) in order to develop policy measures for effective future implementation. The experiences of the three projects show that transport PPP policy is indeed feasible in SSA. However, to realise its full applicability, proper policy actions and measures must be carefully observed and these include effective and efficient stakeholder management, transparent and competitive tendering process, high participation of local investors, stable macro-economic conditions and strong government commitment and regulatory framework. The projects experiences and policy actions developed are impactful in accelerating transport infrastructure development through PPP approach in SSA. Hence it is hoped that policy-makers and practitioners would be informed on the key strategies to employ in implementing future projects. 相似文献
993.
Effects of intersection field of view on emergent collision avoidance performance at unsignalized intersections: analysis based on driving simulator experiments
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Proper intersection sight distance can effectively lower the possibility of intersection accidents. American Association of State Highway and Transportation Officials (2011) provide a series of recommended dimensions of intersection sight triangles for uncontrolled and stop/yield‐controlled intersections. However, in reality, although the actual intersection design for unsignalized intersections satisfies the requirements of sight distance and clear sight triangle in American Association of State Highway and Transportation Officials' guideline, there are still a large number of crashes occurring at unsignalized intersections for drivers running stop/yield signs or failing to slow down. This paper presents a driving simulator study on pre‐crash at intersections under three intersection field of view (IFOV) conditions. The aim was to explore whether better IFOVs at unsignalized intersections improve their emergent collision avoidance performance under an assumption of valid intersection sight distance design. The experimental results show drivers' ability to identify potential hazards to be significantly affected by their IFOVs. As drivers' IFOV improved, drivers were more likely to choose braking actions to avoid collisions. Better IFOVs were also associated with significant increases in brake time to intersection and significant reductions in deceleration rate and crash rate, thus leading to a lower risk of traffic crash involvement. The results indicate that providing a better IFOV for drivers at intersections should be encouraged in practical applications in order to improve drivers' crash avoidance capabilities. Copyright © 2016 John Wiley & Sons, Ltd. 相似文献
994.
S. J. Lee S. J. Jeong W. S. Kim C. B. Lee 《International Journal of Automotive Technology》2008,9(6):659-670
The use of a diesel particulate filter (DPF) in a diesel aftertreatment system has proven to be an effective and efficient
method for removing particulate matter (PM) in order to meet more stringent emission regulations without hurting engine performance.
One of the favorable PM regeneration technologies is the NO2-assisted regeneration method due to the capability of continuous regeneration of PM under a much lower temperature than that
of thermal regeneration. In the present study, the thermal behavior of the monolith during regeneration and the conversion
efficiency of NO2 from NO with an integrated exhaust system of a diesel oxidation catalyst (DOC) and DPF have been predicted by one-channel
numerical simulation. The simulation results of the DOC, DPF, and integrated DOC-DPF models are compared with experimental
data to verify the accuracy of the present model for the integrated DOC and DPF modeling. The effects of catalyst loading
inside the DOC and the volume ratio between the DOC and DPF on the pressure drop, the conversion efficiency, and the oxidation
rate of PM, have been numerically investigated. The results indicate that the case of the volume ratio of ‘DOC/DPF=1.5’ within
the same diameter of both monoliths produced close to the maximum conversion efficiency and oxidation rate of PM. Under the
engine operating condition of 175 kW at 2200 rpm, 100% load with a displacement of 8.1, approximately 55 g/ft3 of catalyst (Pt) loading inside the DOC with the active Pt surface of 5.3 m2/gpt was enough to maximize the conversion efficiency and oxidation rate of PM. 相似文献
995.
C. Oh Y. S. Kang Y. Youn A. Konosu 《International Journal of Automotive Technology》2008,9(2):191-196
Pedestrian-related accidents are considered to be the most serious of traffic accidents due to the associated high fatality
rates. In Korea, pedestrian fatalities accounted for approximately 40% of all traffic-related fatalities in 2004. Significant
efforts have been made to develop effective countermeasures for pedestrian-vehicle collisions. A basis for devising such countermeasures
is to understand the characteristics of pedestrian-vehicle collisions. This study develops a pedestrian fatality model capable
of predicting the probability of fatality in pedestrian-vehicle collisions. Binary logistic regression and a probabilistic
neural network (PNN) are employed to estimate the probability of pedestrian fatality. Pedestrian age, vehicle type and collision
speed are used as independent variables of the fatality model. The models developed herein are valuable tools that can be
used to direct safety policies and technologies associated with pedestrian safety. 相似文献
996.
PSO algorithm-based parameter optimization for HEV powertrain and its control strategy 总被引:1,自引:0,他引:1
The coordination between the powertrain and control strategy has significant impacts on the operating performance of hybrid
electric vehicles (HEVs). A comprehensive methodology based on Particle Swarm Optimization (PSO) is presented in this paper
to achieve parameter optimization for both the powertrain and the control strategy, with the aim of reducing fuel consumption,
exhaust emissions, and manufacturing costs of the HEV. The original multi-objective optimization problem is converted into
a single-objective problem with a goal-attainment method, and the principal parameters of powertrain and control strategy
are set as the optimized variables by PSO, with the dynamic performance index of HEVs being defined as the constraint condition.
Computer simulations were carried out, which showed that the PSO scheme gives preferable results in comparison to the ADVISOR
method. Therefore, fuel consumption and exhaust emissions of HEVs can be effectively reduced without sacrificing dynamic performance
of HEVs. 相似文献
997.
Y. S. Pyoun H. T. Kim Y. C. Lee A. Gafurov H. Kim D. H. Jung 《International Journal of Automotive Technology》2008,9(1):61-70
Surface topology, cone angle and the forces acting on the cone of the clutch type limited slip differential (LSD) are major
design parameters for the bias ratio and the noise condition. Therefore much research has been dedicated to these developments
but the results have been used to submit patents. A new cone type limited slip differential for sport utility vehicles and
recreational vehicles, which has a very simple structure and easy compliance with the vehicle performance, has been developed
by the axiomatic approach and the ultrasonic nano crystal surface modification (UNSM) technology. The design criteria and
optimal value of the design parameters are determined by the axiomatic approach utilizing CAE tools. Test methodologies in
a test rig and in a vehicle were also developed. Test results showed good performance of bias ratio and noise level but durability
is still under testing. This study is an extension of F2006P266, FISITA 2006. 相似文献
998.
T. H. Hwang K. Park S. -J. Heo S. H. Lee J. C. Lee 《International Journal of Automotive Technology》2008,9(1):17-27
The performance of most electronic chassis control systems in the past has been optimized individually. Recently, a great
research effort has been dedicated to the integration of chassis control systems in an effort to improve the vehicle performance.
This involves orchestration of individual control modules so that they can jointly contribute to the enhancement of their
control effect. In this research, two integrated control logics for AFS (Active Front Steering) and ESP (Electronic Stability
Program) have been developed. Of the two logics, one uses a supervisor that rules over the individual modules. The other logic
uses a CL (Characteristic Locus) method, which is a frequency-domain multivariable control technique. The two logics have
been tested under various driving conditions to investigate their control effects. The results indicate that the proposed
integrated control logics can yield vehicle performance that is superior to that of the individual control modules without
any integration scheme. 相似文献
999.
Combined control of a regenerative braking and antilock braking system for hybrid electric vehicles 总被引:1,自引:0,他引:1
D. Peng Y. Zhang C. -L. Yin J. -W. Zhang 《International Journal of Automotive Technology》2008,9(6):749-757
Most parallel hybrid electric vehicles (HEV) employ both a hydraulic braking system and a regenerative braking system to provide
enhanced braking performance and energy regeneration. A new design of a combined braking control strategy (CBCS) is presented
in this paper. The design is based on a new method of HEV braking torque distribution that makes the hydraulic braking system
work together with the regenerative braking system. The control system meets the requirements of a vehicle longitudinal braking
performance and gets more regenerative energy charge back to the battery. In the described system, a logic threshold control
strategy (LTCS) is developed to adjust the hydraulic braking torque dynamically, and a fuzzy logic control strategy (FCS)
is applied to adjust the regenerative braking torque dynamically. With the control strategy, the hydraulic braking system
and the regenerative braking system work synchronously to assure high regenerative efficiency and good braking performance,
even on roads with a low adhesion coefficient when emergency braking is required. The proposed braking control strategy is
steady and effective, as demonstrated by the experiment and the simulation. 相似文献
1000.
H. N. Kim T. J. Kim B. C. Choi M. T. Lim 《International Journal of Automotive Technology》2008,9(5):563-570
The objective of this experimental study is to investigate the characteristics of the size distribution and the number concentration
of PM (particulate matters) emitted from the diffusion flame of a boiler burner, which has the same type of combustion as
a diesel engine. This study is performed to investigate the emission characteristics of nanoparticles generated from diffusion
combustion in diesel fuel, and it considered fuel factors and the reaction characteristics of the nanoparticles on the DOC
(Diesel oxidation catalyst). The factors examined in this experiment included the sulfur content in the fuel, the blend of
the diesel fuel containing biodiesel and bio-ethanol, and the concentration of engine oil (0.1% and 1.0%) blended with diesel
fuel. The particle size distribution of the nanoparticles exhausted from the boiler burner was measured by an SMPS (scanning
mobility particle sizer). The number concentration of PM that were smaller than 70 nm in diameter greatly increased in the
rear of the DOC when fuel containing 250 ppm of sulfur was used. The experiment also suggested that the particle number concentration
in both the front and rear of the DOC was lower when ULSD (ultra low sulfur diesel) fuel blended with biodiesel and bio-ethanol,
which are oxygenated fuels, was used than when only ULSD fuel was used. The higher the content of engine oil in the fuel,
the higher the particle number concentration was in the front and rear of the catalyst. When the first dilution air temperature
is increased from 30°C to 180°C, the nanoparticle number concentration dramatically dropped in the rear of the catalyst when
fuel containing 250 ppm of sulfur was used, while the particle size distribution remained almost the same when the fuel with
engine oil was used. 相似文献