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581.
The brake and steering systems in vehicles are the most effective actuators that directly affect the vehicle dynamics. In general, the brake system affects the longitudinal dynamics and the steering system affects the lateral dynamics; however, their effects are coupled when the vehicle is braking on a non-homogenous surface, such as a split-mu road. The yaw moment compensation of the steering control on a split-mu road is one of the basic functions of integrated or coordinated chassis control systems and has been demonstrated by several chassis suppliers. However, the disturbance yaw moment is generally compensated for using the yaw rate feedback or using wheel brake pressure measurement. Access to the wheel brake pressure through physical sensors is not cost effective; therefore, we modeled the hydraulic brake system to avoid using physical sensors and to estimate the brake pressure. The steering angle controller was designed to mitigate the non-symmetric braking force effect and to stabilize the yaw rate dynamics of the vehicle. An H-infinity design synthesis was used to take the system model and the estimation errors into account, and the designed controller was evaluated using vehicle tests. 相似文献
582.
M. H. Lee K. S. Lee H. G. Park Y. C. Cha D. J. Kim B. Kim S. Hong H. H. Chun 《International Journal of Automotive Technology》2012,13(5):801-807
This paper proposes a lateral control system for an unmanned vehicle that is designed to improve the responsiveness of the system with the use of a PD control. The vehicle heading error can be stabilized, and the transient response characteristics can be improved using the proposed controller. A mathematical model of the vehicle dynamics using two degrees of freedom was developed for the controller design. The waypoint tracking method for autonomous navigation was tested with incorporation of the Point-to-Point algorithm with position and heading measurements received from GPS receivers via Kalman filtering. The performance of the designed controller was verified through experiments with a real vehicle. 相似文献
583.
J. -H. Choi S. -H. Choi D. Park C. -H. Park B. -O. Rhee D. -H. Choi 《International Journal of Automotive Technology》2012,13(2):273-277
The quality of an injection molded part is largely affected by the mold cooling. Consequently, this makes it necessary to
optimize the mold cooling circuit when designing the part but prior to designing the mold. Various approaches of optimizing
the mold cooling circuit have been proposed previously. In this work, optimization of the mold cooling circuit was automated
by a commercial process integration and design optimization tool called Process Integration, Automation and Optimization (PIAnO),
which is often used for large automotive parts such as bumpers and instrument panels. The cooling channels and baffle tubes
were located on the offset profile equidistant from the part surface. The locations of the cooling channels and the baffle
tubes were automatically generated and input into the mold cooling computer-aided engineering program, Autodesk Moldflow Insight
2010. The objective function was the deviation of the mold surface temperature from a given design temperature. Design variables
in the optimization were the depths, distances and diameters of the cooling channels and the baffle tubes. For a more practical
analysis, the pressure drop and temperature drop were considered the limited values. Optimization was performed using the
progressive quadratic response surface method. The optimization resulted in a more uniform temperature distribution when compared
to the initial design, and utilizing the proposed optimization method, a satisfactory solution could be made at a lower cost. 相似文献
584.
Dan B. Marghitu David G. Beale S.C. Sinha 《Vehicle System Dynamics: International Journal of Vehicle Mechanics and Mobility》1997,28(1):41-55
Computer simulations of a driven vehicle are performed to assess and quantify the automobile stability. The analytical methodology is based on PoincarS maps and Floquet theory, which are commonly used to investigate the stability of periodic systems. The approach accommodates the study of the complex dynamics of vehicle locomotion under various configurations of the system. The proposed method does not require any knowledge regarding the inner structure of the vehicle model. Kinematic data is simply collected at the specific instants to conduct the analysis. It is found that this method has the potential for real time warning and control of vehicle instabilities. 相似文献
585.
A Lowry-type land use-transport model stratified both by socio-economic group and urban sub-region is described. The parameters of this model are calibrated from a 1969 urban travel survey conducted in Delhi. Parameter magnitudes are estimated for several versions of the model and the qualities of these calibrations are reported. Applications of the calibrated models to the analysis of alternative development concepts for the Delhi urban region are described. 相似文献
586.
Douglass B. Lee Jr. 《Transportation》1973,2(2):195-218
Urban transit in the United States is going through a crisis of rising costs, increasing fares, falling patronage, and concomitant
service reductions; typical of the pattern is San Francisco’s Municipal Railway, the agency in charge of all the City’s transit.
From a basic fare of 15c in 1969, two increases brought the fare to 25c by 1972, and cut sharply into a previously stable
patronage. The “Muni”, in an effort to reduce costs and meet its budgeted deficit, attempted to reduce service by ten to fifteen
percent. From an analysis of the data which could be obtained, it appears that neither efficiency not equity in the City would
have been served by the proposed cutbacks. The analysis draws from a variety of sources and methods in exploring the interactions
within the transportation system and within the city budget. 相似文献
587.
A. B. Perlman Clive L. Dym 《Vehicle System Dynamics: International Journal of Vehicle Mechanics and Mobility》1980,9(2):61-68
In this paper a Lyapunov function is generated for the linearized equations governing a steel wheelset on steel rails. Thus the authors attack the asymmetric problem, and successfully apply Ingwerson's method for constructing Lyapunov functions. The stability criteria applied to this function yield a closed-form expression for the critical forward speed of the wheelset. Thus the authors retain the advantage of Lyapunov's direct method by obtaining an explicit solution for the critical speed. And, although this linearized result has been obtained by other methods, the result is provocative because it suggests that a similar attack on the intractable nonlinear problem (currently being mounted by the authors) may indeed bear fruit. 相似文献
588.
J. B. Chapman 《Maritime Policy and Management》1979,6(2):101-118
This paper discusses the growth of ro-ro services operating to and from Marseilles and the adaption of port structures to facilitate this growth. The concluding section of Part 1 of the paper analyses throughput performance. 相似文献
589.
电动车组的故障中,40%是发生在牵引电动机和电气设备上.因此应采用更经济、更安全、对旅客和维护人员都更方便的新型电动车组代替已经老化的、使用寿命已到期的直流近郊列车.ЭТ2A型就是新型电动车组之一.文章介绍了其技术参数,分析了其电路原理和技术特点. 相似文献
590.
简述了IGBT牵引变流器的发展沿革,比较了IGBT与GTO等元件的功率要求和工作特性,分析了IGBT牵引变流器的发展前景,介绍了IGBT牵引变流器的应用实例,得出了在各功率等级的牵引变流器中,IGBT将完全取代GTO晶闸管的结论. 相似文献