VSC of a servo-actuated ATR90-type pantograph

One of the problems in high-speed-train transportation systems is related to the current collection quality, that can dramatically decrease because of oscillations of the pantograph-catenary system. In the recent literature this problem has been addressed by means of active pantographs. In order to reduce the costs, a common requirement of the train companies is that the control system could be applied to the actually used pantographs. In this paper we present the preliminary results about the possible implementation of VSC techniques on a servo-actuated symmetric pantograph that can be obtained by modifying a passive high-speed pantograph Ansaldo ATR90, currently used by Italian Railways. We consider the equivalent mechanical characteristics of the catenary as uncertainties to compensate for, and the use of a robust, nonlinear, control scheme is proposed. Recent results about the influence of fast actuators in second-order sliding mode control schemes are exploited to avoid the destroying effect of a resonant actuator and the system performance are verified by simulation, under the hypothesis of knowing the actual contact force. The contact force results to be very close to the desired value in various operating conditions.