Comparison of different control approaches aiming at enhancing the comfort of a railway vehicle

In the last years magneto-rheological dampers have been successfully used to realize semi-active suspension systems for automotive applications. Due to their dimension flexibility and the wide range of forces they can exert, these devices can be used even for railway applications, such as in the present work. This paper is focused on the design, evaluation and comparison of different control strategies for semi-active suspension system on the secondary suspension stage of an high speed train. In particular, the classical simulation of mechanical impedance, also known as “skyhook damper”, and a “sliding mode” control exploiting the gradient projection method in order to cope with linear constraints on the forces, have been compared to a traditional passive suspension system. In order to test the proposed control strategies and to simplify the control gain refinement, a multi-body model of the railway vehicle have been built by means of Matlab/Simulink™. Moreover, in order to fairly compare the different control strategies, a performance index has been defined, which is based on the comfort test that is usually done on real trains.