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271.
Optimal Preview Control of a Two-dof Vehicle Model Using Stochastic Optimal Control Theory 总被引:2,自引:0,他引:2
S. Senthil S. Narayanan 《Vehicle System Dynamics: International Journal of Vehicle Mechanics and Mobility》1996,25(6):413-430
An optimal preview control algorithm is applied to a two degree of freedom(dof) vehicle model travelling with constant velocity on a randomly profiled road. The road roughness is modelled as a homogeneous random process being the output of a linear first order filter to white noise. The input from the road irregularity is assumed to be measured at some distance in front of the vehicle and this measured infonnation is utilized by the active controller to prepare the system for the ensuing input. The preview control algorithm is obtained by minimizing a quadratic performance index and by describing the average behaviour of the system by the covariance matrix of the vehicle response state vector. Results are presented for full state feedback and significant improvements in sprung mass acceleration, suspension working space and road holding are observed. 相似文献
272.
R. G. Langlois R. J. Anderson 《Vehicle System Dynamics: International Journal of Vehicle Mechanics and Mobility》1995,24(1):65-97
The potential performance improvement using preview control for active vehicle suspension was first recognized in the late nineteen sixties. All work done since that time has been based on optimal control theory using simple vehicle models.
In this article, the performance of quarter vehicle preview controllers when applied to a real off-road vehicle is simulated using both two degree of freedom quarter and ten degree of freedom full vehicle models. The results, which are compared with non-preview active and conventional passive suspensions, confirm that preview control reduces vertical acceleration of the body centre of gravity, which results in improved ride quality. Further, reductions in pitch and roll motion result from smaller vertical displacements of the vehicle quarters. Coupling between quarters, through the vehicle body, appears to have a smoothing effect on the control.
As an alternative to optimal control theory based controllers, a simple ad hoc preview controller based on isolating the vehicle body from dynamic loads transmitted through the suspension is proposed. Simulation results show that such a controller outperforms the optimal control theory based controllers over small discrete disturbances but responds poorly to disturbances encountered from other than steady state. 相似文献
In this article, the performance of quarter vehicle preview controllers when applied to a real off-road vehicle is simulated using both two degree of freedom quarter and ten degree of freedom full vehicle models. The results, which are compared with non-preview active and conventional passive suspensions, confirm that preview control reduces vertical acceleration of the body centre of gravity, which results in improved ride quality. Further, reductions in pitch and roll motion result from smaller vertical displacements of the vehicle quarters. Coupling between quarters, through the vehicle body, appears to have a smoothing effect on the control.
As an alternative to optimal control theory based controllers, a simple ad hoc preview controller based on isolating the vehicle body from dynamic loads transmitted through the suspension is proposed. Simulation results show that such a controller outperforms the optimal control theory based controllers over small discrete disturbances but responds poorly to disturbances encountered from other than steady state. 相似文献
273.
Identification Methods for Vehicle System Dynamics 总被引:1,自引:0,他引:1
Rainer G. Kallenbach 《Vehicle System Dynamics: International Journal of Vehicle Mechanics and Mobility》1987,16(3):107-127
The paper presents a survey on parameter identification techniques for complex vehicle models. In order to cope with the complexity of the model, the information on the system available from the equations of motion has to be included in the identification process. Basic methods for the solution of this problem are shown. The application of the approach is demonstrated by identification of the vertical automobile dynamics. It is concluded that the presented techniques will become more important with increasing applications of theoretical modeling in vehicle system dynamics. 相似文献
274.
A. D. De Pater 《Vehicle System Dynamics: International Journal of Vehicle Mechanics and Mobility》1988,17(3):127-140
In previous publications the author has described a so-called first-order theory for the motion of a railway vehicle wheelset on a tangent track. In the present report the geometrical aspect of this theory is further evaluated and a method for solving the constraint equations between the coordinates of the wheelset is indicated. 相似文献
275.
276.
西江水运主通道通航枢纽建设关键技术研究 总被引:1,自引:0,他引:1
广西西江航运建设发展有限责任公司 《西部交通科技》2006,(1):19-21
文章主要介绍西部项目西江水运主通道通航枢纽建设研究的背景、内容、成果及关键技术,为其他航运枢纽建设提供了设计、决策的依据,其研究成果具有广阔的应用和参考价值。 相似文献
277.
This paper presents a multiple discrete-continuous econometric structure to model the daily time-investment decisions of couples
in solo- and joint-discretionary activities incorporating intra-personal and inter-personal inter-dependencies. The empirical
model was estimated using data from the 2000 Bay Area Travel Survey. The results indicate evidence of the positive impact
of vehicle availability on independent activity participation and the negative impacts of the presence of children and mandatory
time investments on the joint discretionary-activity engagement of the spouses. In addition, we also find the mandatory- and
maintenance-activity-participation characteristics of the spouse to influence the discretionary activity choices of individuals.
Finally, the analysis also indicates a strong impact of common unobserved factors on the decisions of couples. From a policy
analysis perspective, these results imply that demand-management actions directly impacting one adult could also result in
changes to the activity patterns of his/her spouse and to changes in joint activity participation characteristics.
Dr. Sivaramakrishnan Srinivasan is an Assistant Professor in the Department of Civil and Coastal Engineering at the University of Florida. His research interests
include travel-behavior analysis, activity-based travel-demand modeling, and the application of advanced econometric methods
for transportation problems.
Dr. Chandra R. Bhat has contributed toward the development of advanced econometric techniques for travel behavior analysis, in recognition of
which he received the 2004 Walter L. Huber Award and the 2005 James Laurie Prize from the American Society of Civil Engineers
(ASCE). 相似文献
278.
Should we abandon activity type analysis? Redefining activities by their salient attributes 总被引:3,自引:0,他引:3
Sean T. Doherty 《Transportation》2006,33(6):517-536
This paper poses a challenge and begins a search. The challenge is to reconsider the usefulness of traditional activity types (“work”, “shopping”, etc.) in the understanding and modelling of travel behaviour. The search is for the more salient attributes of activities that may serve to better explain complex travel behaviours—such as activity scheduling and tour formation. In particular, this paper focuses on explicit measures of the spatial, temporal and interpersonal flexibility of activities, along with several traditional attributes (frequency, duration, involved persons, travel time, and location). Data from a recent in-depth week-long activity scheduling survey was used to define and compare these attributes. Results show that considerable variability in the attributes between and within traditional activity groups is evident. This casts considerable uncertainty on assumptions that statically assign levels of spatial, temporal, and interpersonal flexibility to any given activity type. A Principal Components Analysis further revealed eight new distinct clusters of activities that share like attributes. The relative role of each attribute in each component is examined, and subjective interpretations emerged (e.g., “Long and frequent”, “Space and time flexible” “Social networking”). The implications of these results for future model development and research are discussed. Future research should continue to expand the search for salient attributes and link them more directly to decision processes. 相似文献
279.
The need for acquiring the current-year traffic data is a problem for transport planners since such data may not be available
for on-going transport studies. A method is proposed in this paper to predict hourly traffic flows up to and into the near
future, using historical data collected from the Hong Kong Annual Traffic Census (ATC). Two parametric and two non-parametric
models have been employed and evaluated in this study. The results show that the non-parametric models (Non-Parametric Regression
(NPR) and Gaussian Maximum Likelihood (GML)) were more promising for predicting hourly traffic flows at the selected ATC station.
Further analysis encompassing 87 ATC stations revealed that the NPR is likely to react to unexpected changes more effectively
than the GML method, while the GML model performs better under steady traffic flows. Taking into consideration the dynamic
nature of the common traffic patterns in Hong Kong and the advantages/disadvantages of the various models, the NPR model is
recommended for predicting the hourly traffic flows in that region. 相似文献
280.
T. A. Wenzel K. J. Burnham M. V. Blundell R. A. Williams 《Vehicle System Dynamics: International Journal of Vehicle Mechanics and Mobility》2006,44(2):153-171
The article demonstrates the implementation of a model-based vehicle estimator, which can be used for combined estimation of vehicle states and parameters. The estimator is realised using the dual extended Kalman filter (DEKF) technique, which makes use of two Kalman filters running in parallel, thus 'splitting' the state and parameter estimation problems. Note that the two problems cannot be entirely separated due to their inherent interdependencies. This technique provides several advantages, such as the possibility to switch off the parameter estimator, once a sufficiently good set of estimates has been obtained. The estimator is based on a four-wheel vehicle model with four degrees of freedom, which accommodates the dominant modes only, and is designed to make use of several interchangeable tyre models. The paper demonstrates the appropriateness of the DEKF. Results to date indicate that this is an effective approach, which is considered to be of potential benefit to the automotive industry. 相似文献