Modelling dynamics of certain class of discrete multi-body systems based on direct method of the dynamics of relative motion

The paper presents the author's method of numerical modelling multi-body systems of a rail vehicle class. The method exploits dynamics of relative motion, which describes perturbations in general motion of the vehicle. Quite a few original elements are included in the author's approach. This approach is compared to other possibilities of describing dynamics of multi-body systems in relative motion. The author's method makes use of Kane's equations that are opposed in the paper to the Newton-Euler approach that is used most often in the analogous applications. Numerical implementation of the theoretical results is also presented and a sample of the corresponding numerical analysis. Both these show the particular way to model dynamics of such systems efficiently and what consequences might be of the simplification in the description of relative motion. This appears to be more important than it is usually believed, particularly when accelerating or breaking the vehicle.