Assessment of the Performance of Tilt System Controllers Roger Goodall and Argyrios Zolotas Loughborough University, Department of Electronic and Electrical Engineering Jeremy Evans AEAT Technology SYNOPSIS The paper describes an overall approach for determining tilt control system performance. Firstly the issues relating to dynamic performance are reviewed, then some trade-off graphs are given, based upon the P CT index approach which is now accepted as a European Standard. These graphs inter-relate vehicle speed, the maximum tilt angle, and the cant deficiency compensation factor, and help to determine the optimum operational conditions for a tilting train. Secondly a method for quantifying the dynamic performance is explained, in particular aimed at a comprehensive assessment of different tilt control laws. Simulation results are included to illustrate the method, and some preliminary conclusions regarding different controllers are presented. 1 INTRODUCTION Although active tilting has become a standard railway technology, a number of issues re- main which need to be resolved for determining the performance of tilting trains. One of these relates to motion sickness, and research is on-going in this area (1, 2). How- ever there are also uncertainties relating to the more basic issue of optimising the tilt con- troller design, in particular the dynamic performance. This paper presents an ap- praisal of these dynamic considerations and proposes an assessment method, illustrat- ing the technique with an example tilt control system. There is a general acceptance that tilting can provide typically 30% increase in speed through curves, but this is often based upon criteria such as the maximum track force and the quasi-static response on a steady curve. However the P CT index, which has now been accepted in Europe (3), provides a means of assessing the fundamental re- sponse on curve transitions in terms of passenger comfort, and it is possible to use this in- dex in order to assess rigorously the use of tilt to provide an increased operating speed,