排序方式: 共有36条查询结果,搜索用时 0 毫秒
31.
Vittore Cossalter Alberto Doria Stefano Garbin Roberto Lot 《Vehicle System Dynamics: International Journal of Vehicle Mechanics and Mobility》2006,44(4):339-355
In many European towns, the demand for fast and efficient mobility is frequently satisfied by means of two-wheeled vehicles. The improvement of comfort of two-wheeled vehicles used by tired and busy workers can increase safety in ground transport. Nowadays, multibody codes make it possible to predict the ride comfort of two-wheeled vehicles by means of time-domain or frequency-domain simulations. Comfort indices can be developed by post-processing the results of numerical simulations. This task is difficult, because the indices should depend on vehicle characteristics and should be independent of road quality and vehicle speed. Poor quality roads may generate nonlinear effects. Speed influences the trim of the vehicle and the wheelbase filtering, which takes place because the same road unevenness excites the front and rear wheel with a time delay which depends on the vehicle's speed.
In this paper, the comfort of two-wheeled vehicles is studied by means of a frequency-domain approach. The wheelbase filtering is averaged considering typical missions of the vehicle. The missions are journeys with a forward speed that assumes different values according to a probability density function. Indices of comfort are calculated taking into account the human sensitivity. The examples show that the proposed comfort indices depend on suspensions' characteristics and, hence, are useful design tools. Finally, some time-domain calculations are carried out to give emphasis to nonlinear effects and to show the limits of the frequency-domain analysis. 相似文献
In this paper, the comfort of two-wheeled vehicles is studied by means of a frequency-domain approach. The wheelbase filtering is averaged considering typical missions of the vehicle. The missions are journeys with a forward speed that assumes different values according to a probability density function. Indices of comfort are calculated taking into account the human sensitivity. The examples show that the proposed comfort indices depend on suspensions' characteristics and, hence, are useful design tools. Finally, some time-domain calculations are carried out to give emphasis to nonlinear effects and to show the limits of the frequency-domain analysis. 相似文献
32.
Aldo Balestrino Ottorino Bruno Alberto Landi Luca Sani 《Vehicle System Dynamics: International Journal of Vehicle Mechanics and Mobility》2000,33(2):69-89
In this paper an innovative active pantograph for high-speed trains is proposed. The results presented are based on extensive simulation tests. The parameters used in the simulation are those of a real pantograph for high-speed trains: the pantograph model is modified by adding a wire actuation, in order to exert a constant contact force between the moving pantograph and the overhead contact wire. A wire-actuated control and contact force observers are proposed as effective solutions in the case of a possible implementation. 相似文献
33.
Vittore Cossalter Alberto Doria Roberto Lot 《Vehicle System Dynamics: International Journal of Vehicle Mechanics and Mobility》2000,34(3):175-198
A mathematical model for the in-plane dynamic analysis of motorcycles is presented and the performance during an emergency braking manoeuvre is analysed. The effects of braking torque amplitude and time constant are discussed and the problems of lock-up and loss of contact of the rear wheel are highlighted. The suspensions' vibrations during braking are analysed by means of modal analysis. An optimisation method is developed in order to find the braking torque and the suspension parameters that minimise the stopping distance. The method takes the complete dynamic behaviour of the vehicle during braking into account and is based on a non-derivative minimisation algorithm. Several results are presented that show the possibility of shortening the stopping distance by optimum design of one or both of the suspensions. 相似文献
34.
An Alternative Method to Determine the Magic Tyre Model Parameters Using Genetic Algorithms 总被引:2,自引:0,他引:2
J. A. Cabrera A. Ortiz E. Carabias A. Simon 《Vehicle System Dynamics: International Journal of Vehicle Mechanics and Mobility》2004,41(2):109-127
Summary Tyre behavior plays an important role in vehicle dynamics research. Knowledge of tyre properties is necessary to properly design vehicle components and advance control system. For that purpose mathematical models of the tyre are being used in vehicle simulation models. The Magic Formula Tyre Model is a semi-empirical tyre model which describes tyre behavior quite accurately. The Magic Formula Tyre Model needs a set of parameters to describe the tyre properties; the determination of these parameters is dealt with in this paper. A new method based on genetic techniques is used to determine these parameters. The main advantages of the method are its simplicity of implementation and its fast convergence to optimal solution, with no need of deep knowledge of the searching space. So to start the search, it is not necessary to know a set of starting values of the Magic Formula parameters. The comparison between analytical optimization methods and the method proposed is discussed in this paper. 相似文献
35.
Andrés Weintraub Carmen Ortiz Jaime González 《Transportation Research Part B: Methodological》1985,19(2):113-122
We consider the Frank-Wolfe algorithm in the context of the traffic assignment problem. The slow-convergence characteristics close to the optimum solution of this popular approach are well known. Several proposals have improved on the original method by modifying the search direction. We propose modifying the step size, which leads to very significant improvements in efficiency. 相似文献
36.
Rodriguez-Valencia Alvaro Vallejo-Borda Jose Agustin Barrero German A. Ortiz-Ramirez Hernan Alberto 《Transportation》2022,49(3):791-814
Transportation - More and more cities worldwide are striving for sustainability and livability. Measuring the service or performance of local-scale spaces for pedestrians and bicyclists to better... 相似文献