Analysis of dynamics of a scaled PRT (personal rapid transit) vehicle

Abstract

This publication provides a discussion concerning research aimed to analyse running properties of PRT vehicles. A PRT vehicle is guideway vehicle equipped with rubber-tyred wheels, running on a flat subgrade guideway of special design. The guideway cross-section is similar to that of a C-shaped beam with two outer limiting edges. This specific design characteristic of the running system of PRT vehicles distinguishes them from typical rail vehicles, where the latter can move along the track by the action of a unit referred to as the centring mechanism, operating at the contact of profiled wheels with the running rail head. In a PRT vehicle, the typical railway centring mechanism has been removed and substituted with a system of outer and inner rollers, forming what is referred to as a passive switch system, responsible for carrying the vehicle along the guideway and within the boundaries delimited by its edges by the action of the rollers’ contact forces. Compared to railway infrastructure, this system is characterised by different dynamic properties, and it has not been sufficiently researched yet. The goal of this article is to analyse motion stability of a PRT vehicle with a passive switch system and having the following structural features: wheel sets with beams turning against the vehicle body and independently revolving wheels, non-turning rubber-tyred and non-profiled wheels rolling on a flat surface, and a set of outer and inner rollers performing the passive switch system’s functions. The paper describes a PRT vehicle simulation model. It has been assumed that the model’s design and parameters describe a scaled vehicle/guideway system whose physical model is actually set at a laboratory testing station on premises of the Warsaw University of Technology. The article provides results of simulation studies of motion stability pertaining to the following characteristics: radial positioning, yawing, sticking to the guideway edge, self-excited vibrations of wheel sets as well as free vibrations. It also discusses results of an analysis of sensitivity of the model’s parameters against selected control parameters (model’s design parameters) and assessment indicators which describe the intensity of the yaw type torsional vibrations of wheel sets. The article closes with a discussion on the potential to use the results of the tests conducted under the study on the scaled vehicles in question for purposes of vehicles of real-life dimensions.