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311.
Desired yaw rate and steering control method during cornering for a six-wheeled vehicle 总被引:1,自引:0,他引:1
S. -J. An K. Yi G. Jung K. I. Lee Y. -W. Kim 《International Journal of Automotive Technology》2008,9(2):173-181
This paper proposes a steering control method based on optimal control theory to improve the maneuverability of a six-wheeled
vehicle during cornering. The six-wheeled vehicle is believed to have better performance than a four-wheeled vehicle in terms
of its capability for crossing obstacles, off-road maneuvering and fail-safe handling when one or two of the tires are punctured.
Although many methods to improve the four-wheeled vehicle’s lateral stability have been studied and developed, there have
only been a few studies on the six-wheeled vehicle’s lateral stability. Some studies of the six-wheeled vehicle have been
reported recently, but they are related to the desired yaw rate of a four-wheeled vehicle to control the six-wheeled vehicle’s
maneuvering during corning. In this paper, the sideslip angle and yaw rate are controlled to improve the maneuverability during
cornering by independent control of the steering angles of the six wheels. The desired yaw rate that is suitable for a six-wheeled
vehicle is proposed as a control target. In addition, a scaled-down vehicle with six drive motors and six steering motors
that can be controlled independently is designed. The performance of the proposed control methods is verified using a full
model vehicle simulation and scaled-down vehicle experiment. 相似文献
312.
This paper is the second invstigation on the effect of fuel stratification on flame propagation. In the previous work, the
characteristics under the no port-generated swirl condition, i.e., the conventional case was studied. In this work, the flame
development under the low swirl condition was considered. For this purpose, the initial flame development and propagation
were visualized under different axially stratified states in a modified optical single cylinder SI engine. The images were
captured by an intensified CCD camera through the quartz window mounted in the piston. Stratification was controlled by the
combination of the port swirl ratio and injection timing. These were averaged and processed to characterize the flame propagation.
The flame stability was estimated by the weighted average of flame area and luminosity. The stability was also evaluated through
the standard deviation of flame area and propagation distance and through the mean absolute deviation of the propagating direction.
The results show that the flame-flow interaction determines the direction of flame propagation and that the governing roles
of the two factors vary according to the stratified state and the location in the cylinder. In addition, the flame development
and the initial flame stability are strongly dependent on the stratified conditions, and the initial flame stability is closely
related to the engine stability and lean misfire limit. Lastly, there is no essential difference in gasoline and CNG flame
propagation characteristics. 相似文献
313.
This paper presents a steering control method for lane-following in a vehicle using an image sensor. With each image frame
acquired from the sensor, the steering control method determines target position and direction, and constructs a travel path
from the current position to the target position either as an Arc-path or S-path. The steering angle is calculated from the
travel path thus generated, and the vehicle follows the travel path via motor-control. The method was tested using a vehicle
dubbed as KAV (Korea Autonomous Vehicle) along an expressway (Seoul Inner Beltway) trajectory with a variety of radii (50
m ∼ 300 m) while traveling at a speed of 60 km/h to 80 km/h. Compared with an experienced human driver, the method showed
little much difference in performance in terms of lane-center deviation. The proposed method is currently employed for high
speed autonomous driving as well as for stop and go traffic. 相似文献
314.
This paper proposes a new neuron control strategy for an active vehicle suspension system, with the emphasis on the study
of multivariable and uncertain suspension characteristics. The novelty of this strategy is in the use of integrated error,
which consists of multiple output errors in the regulated plant. By combining the integrated error approach with the traditional
neuron control (TNC), integrated error neuron control (IENC) is presented. It provides a direct control to the multiple outputs
of the control plant simultaneously. Taking a quarter-car model as an example, the proposed control strategy is applied and
comparative simulations are carried out with various vehicle parameters and road input conditions. Simulation results prove
the effectiveness and robustness of the proposed IENC method. In addition, the newly proposed neuron scheme provides a simple
yet efficient new possibility for the control of a class of uncertain multivariable systems similar to an active vehicle suspension. 相似文献
315.
The impact of high-speed technology on railway demand 总被引:1,自引:0,他引:1
This paper estimates a passenger railway demand function to analyse effects arising from the introduction and use of high-speed
technologies. The paper reports estimates of demand elasticities with respect to price, income, quality of service and a range
of exogenous characteristics. The results show that travel time savings from conventional high-speed technology have a larger
impact on passenger demand than tilting train technology. The introduction of conventional high-speed technology is associated
with an 8% increase in passenger railway demand. Increasing the use of either type of high-speed technology appears to induce
small positive effects on demand beyond those obtained from usual traffic density increases on non-high-speed existing technology.
Antonio Couto is an assistant professor in the Faculty of Engineering (FEUP) at the University of Porto. He received his PhD from FEUP in 2005 having completed a thesis in railway transport economics. His research focuses on issues related to transport economics and infrastructures. Daniel J. Graham is a Reader in the Centre for Transport Studies at Imperial College London. He specialises in the economics of transport, focusing in particular on modelling the implications of transport provision and accessibility for productivity and economic growth. 相似文献
Daniel J. Graham (Corresponding author)Email: |
Antonio Couto is an assistant professor in the Faculty of Engineering (FEUP) at the University of Porto. He received his PhD from FEUP in 2005 having completed a thesis in railway transport economics. His research focuses on issues related to transport economics and infrastructures. Daniel J. Graham is a Reader in the Centre for Transport Studies at Imperial College London. He specialises in the economics of transport, focusing in particular on modelling the implications of transport provision and accessibility for productivity and economic growth. 相似文献
316.
Dimitrios A. Tsamboulas Anastasios Nikoleris 《Transportation Research Part A: Policy and Practice》2008,42(10):1274-1282
There are cases when passengers are willing to pay a premium to reduce the travel time, in particular when the trip has to be made. This paper aims to provide insight into factors that determine passengers’ willingness to pay to reduce travel time for their ground access to an airport. A methodology is developed that comprises two steps: the identification of the passengers with zero willingness to pay and from the rest the estimation of the additional price they are willing to pay to reduce their travel time. For the first step a Probit model was formulated and for the second a linear regression model. To this purpose, data has been collected employing stated preference from passengers at the Athens International Airport. It has been found that a high percentage of passengers have zero willingness to pay, and of the remaining ones those using public transport have a significant willingness to pay to reduce access travel time. The methodology and the models are structured in such a way that their transferability to any airport environment is possible, thus providing a useful tool for decisions relating to airport ground access measures. 相似文献
317.
Understanding of the activity-travel patterns of children is becoming increasingly important to various policy makers. Further,
there is also a growing recognition that intra-household interactions need to be explicitly accommodated in travel models
for realistic forecasts and policy evaluation. In the light of these issues, this paper contributes towards an overall understanding
of the school-travel behavior of children and the related interdependencies among the travel patterns of parents and children.
An econometric model is formulated to simultaneously determine the choice of mode and the escorting person for children’s
travel to and from school. The 2000 San Francisco Bay Area Travel Survey (BATS) data are used in the model estimation process.
Empirical results indicate that the characteristics of child like age, gender, and ethnicity, and employment and work flexibility
characteristics of the parents have strong impacts on the mode choice decisions. In addition, the impacts of some of these
attributes on the choice of mode to school are different from the corresponding impacts on the choice of mode from school. The distance between home and school is found to strongly and negatively impact the choice of walking to and from
school, with the impact being stronger for walking to school. Several land-use and built-environment variables were explored,
but were found not to be statistically significant predictors.
相似文献
Sivaramakrishnan Srinivasan (Corresponding author)Email: |
318.
Konstantinos G. Zografos Konstantinos N. Androutsopoulos Teemu Sihvola 《Transportation》2008,35(6):777-795
Flexible transport services include a wide range of demand responsive transport systems that provide non-conventional passenger
and freight transportation services. Several alternative business models varying according to the local market conditions,
the socio-economic, legal, and institutional framework may be developed for the provision of Flexible Transport Systems (FTS).
The objective of this paper is twofold: first to present an integrated methodological framework for developing and assessing
alternative FTS business models and second to demonstrate its applicability to a case study regarding the prioritization of
alternative FTS business models for the provision of flexible passenger transport services in Helsinki.
相似文献
Teemu SihvolaEmail: |
319.
A.T.Kearney 《上海汽车》2018,(1)
正关于自动驾驶发展进程的预测,业内普遍认同的观点是:自动驾驶汽车将在2025年前后开始呈现爆发式增长;到2035年,人类社会道路上行驶的车辆将有50%实现自动驾驶,届时自动驾驶整车及相关设备、应用的收入规模总计将超过5 000亿美元。1产品定位——从简单的交通工具转变为移动多用途空间无人驾驶首先转变的将是汽车产品自身的定位。在自动驾驶技术成为主流的时代,系统基本上 相似文献
320.
E. S. Sytov A. S. Bratus 《Vehicle System Dynamics: International Journal of Vehicle Mechanics and Mobility》2018,56(4):621-637
This paper discusses the initiative of implementing a GPU-based numerical algorithm for studying various phenomena associated with dynamics of a high-speed railway transport. The proposed numerical algorithm for calculating a critical speed of the bogie is based on the first Lyapunov number. Numerical algorithm is validated by analytical results, derived for a simple model. A dynamic model of a carriage connected to a new dual-wheelset flexible bogie is studied for linear and dry friction damping. Numerical results obtained by CPU, MPU and GPU approaches are compared and appropriateness of these methods is discussed. 相似文献