Showing papers on "Vehicle dynamics published in 1977"

New Results in Driver Steering Control Models

Abstract: The dynamic control properties of drivers and driver/vehicle systems in steering operations have been widely investigated. This paper presents a short review of the combined compensatory, pursuit, ...

Dynamic Interactions Between Vehicles and Elevated, Flexible Randomly Irregular Guideways

Abstract: A dynamic interaction model is formulated for the heave-pitch motion of vehicles crossing elevated flexible, randomly irregular spans. Span dynamic motion due to a vehicle passage is modeled using a Bernoulli-Euler beam model and modal analysis techniques. Four types of random irregularities characteristic of elevated guideways are modeled numerically including vertical span offset, pier misalignment, camber, and surface roughness. Analytical expressions for each irregularity power spectral density are derived and the relative contributions of irregularities to vehicle excitation are examined. The limitations to vehicle passenger comfort levels posed by guideway deflection and irregularity are illustrated for personal and rapid transit types of vehicles.

On the identification of vehicle longitudinal dynamics

Abstract: A functional model of vehicle-propulsion system/roadway-interface dynamics is specified, and a model-matching procedure, wherein closed-loop vehicle longitudinal controllers are employed, is detailed for identifying the parameters of this model. This procedure was employed to determine the longitudinal dynamics of a dual-mode test vehicle. The derived dynamics, which are highly velocity dependent, were validated in a series of full-scale tests in which large-signal inputs were employed. The methodology employed and the general nature of the results, especially the substantial velocity dependence, appear applicable to a wide range of rubber-tired vehicles. The failure to adequately account for such dependence, which arises from the properties of the propulsion system and the propulsion system/roadway interface, could result in a design with little basis in reality.

Railway vehicle dynamics--the emergence of a practical theory

Abstract: The purpose of this paper is to describe achievements made over the past 10 years by British railways in the field of railway vehicle dynamics. The authors feel that the significant change has been to bring the science of railway vehicle dynamics to the status of a practical engineering tool. The new theories permit the quantitative assessment of the behaviour of existing vehicles and the systematic exploration of possible new designs of advanced concept and performance. Section 2 of this report deals with interaction between wheel and rail, section 3 describes the equations of motion and subsequent sections cover in turn dynamic stability, motion in curves, and response to track irregularities and the mechanism of derailment. The nature of the engineering design problem is discussed wherein there are trade-offs between the principal performance indicators. Significant applications of this work to date are discussed.

Guidance and control of maneuvering reentry vehicles

Abstract: Over the past fifteen years, studies and flight tests have brought maneuvering reentry technology to a state of relative maturity. During this period, many vehicle configurations have been investigated and many guidance or steering schemes proposed. This paper is intended to summarize those investigations, few of which have been made available to the technic?al community at large. Three vehicle control configurations (cruciform, bank-to-turn, and fixed trim) and three guidance laws (cross-product, proportional, and tangent cubic) are presented in this paper. Each law is formulated for use with each vehicle configuration. The relative merits and drawbacks of these configurations are discussed.

Periodic motion of vehicles on flexible guideways

Abstract: Periodic motions of vehicles on flexible guideways are explored as candidate "test" motions for optimization studies where it is necessary to compare large numbers of designs under equivalent conditions. Exact and approximate methods are developed for identifying initial conditions that lead to periodic motions of single vehicles or many equally spaced vehicles. Using exact equations, fundamental questions regarding the nature of these motions are addressed (existence, uniqueness, stability, etc.). Approximate equations are developed to reduce the computational burden of examining large numbers of designs. It is shown that the assumptions inherent in the approximate equations are valid provided that vertical accelerations of the vehicles are sufficiently small.

Simulation of Multibody Vehicles Moving over Elastic Guideways1

Abstract: SUMMARY This paper describes the present state of a general purpose computer program for calculating the dynamic response of vehicles travelling over guideways which may be elastic The linearized state-equations of motion for general multibody vehicles are constructed automatically by the program, these equations are supplemented by the equations for the active subsystems Finally, the vehicle system equations are combined with the modal equations for elastic guideways and the complete set of coupled equations is solved simultaneously by numerical integration

Vehicle dynamics -- a practical theory

Abstract: The theories permit quantitative asessment of several aspects of vehicle behavior which it was not previously possible to calculate. These include hunting, response of vehicles to rough track and the compromise necessary between lateral stability and curve negotiation.

A status report on the development of near optimal differential game feedback methods for realistic nonlinear problems

Abstract: Two classes of techniques for generating feedback controls, based on zero-sum perfect information differential game theory, are reviewed. The first class makes use of highly simplified dynamics as an approximation to the actual problem dynamics in order to obtain feed-back controls in closed-form. The second class of techniques uses sophisticated computational algorithms to generate near-optimal feedback controls based on realistic high order nonlinear system dynamics. The advantages and shortcomings of both of these approaches are discussed, along with possible future developments in this area.

Preliminary evaluation of rail vehicles by computer simulation

Abstract: Mathematical models of rail vehicles and track structures developed over the past decade have proven to be invaluable tools in rail transportation research. One important use of these mathematical models is to provide a preliminary evaluation of new rail vehicle and track structure designs, prior to extensive prototype construction and testing.

Model experiments for span-vehicle dynamics

Abstract: The transient dynamics of multiple-span beam-type bridges responding to constant speed, sprung and unsprung vehicle loads are investigated experimentally. Both instrumentation and the severe problems of dynamic modeling of realistic prototypes are considered. Scaling parameters such as vehicle mass to span mass ratio, passage frequency to bridge frequency ratio, vehicle suspension frequency ratios, and loading length to span length ratio are defined and applied to the design of a laboratory test facility. Considered are problems of data retrieval for the bridge dynamics and for the vehicle heave acceleration. The latter data, needed to design safe and comfortable vehicle suspension systems, are essential in future urban and interurban transportation systems. Span data are presented in nondimensional form, suitable for design purposes. Typical data for a six-span bridge show that the peak bending moments may exceed four times their respective static moments for a vehicle at its crawl speed.

Evaluation and correlation of driver/vehicle data. volume ii. technical report

Abstract: The purpose of the study has been to analyze and correlate available handling-related driver/vehicle system response and performance data. This information has been used in an effort to identify safety-relevant vehicle performance characteristics and requirements criteria. Volume 2 contains the following: Determination of vehicle dynamic properties; Regulation tasks; Transient and discrete maneuvers; Considerations for handling requirements.

Simulation and analysis of rail vehicle dynamics

Abstract: This paper discusses current U.S. simulation and analysis efforts in rail vehicle dynamics. It points out the direction that present research is taking, illustrates the scope and magnitude of the problem, and presents selected results from current research programs.

Dynamic aspects of passenger carrying vehicles using controlled d.c. electromagnets

Abstract: The use of controlled dc electromagnetic suspension poses a number of special problems such as interaction through vehicle dynamics and different control loops, noncyclicity of the system and the choice of weighting matrices for high-order systems. In order to develop synthesis procedures for active feedback systems, it is necessary to take into account not only the static but the dynamic interactions between various degrees of freedom such as roll, pitch, yaw, lift and lateral displacement. Further, when controlled dc electromagnetic suspension is employed for passenger carrying vehicles a number of additional characteristics associated with vehicle dynamics must also be considered in addition to stability requirements. Some of these are suspension stiffness, acceleration levels due to guideway roughness and flexibility, damping and dynamic response.