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Due to the oscillating behaviour of the pantograph and the catenary during the movement of the locomotive, the contact force changes to wide limits, resulting in electrical sparks with consequences: premature wear of the contact wire, electromagnetic disturbances, energy loss. Suitable control of the contact force at speeds exceeding 160 km/h may diminish these effects. Due to the particularities of the pantograph-catenary system and many random external factors, existing control methods do not always give the best results. The authors’ research has shown that the contact force signal contains a chaotic component that can be offset by chaos theory methods. Their own studies have demonstrated theoretically and by simulation that this approach can largely eliminate the separating the pantograph from the catenary and will lessen excessive forces. Experimental research, conducted by the authors and presented in this article, has been done in laboratory conditions on a specially built test stand and confirms that this new approach to active pantograph control produces superior results to existing methods.

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The paper introduces some experimental results of applying the theory of optimal control of high power reversible drives in a rolling mill from the steel plant of Hunedoara, Romania, starting year 2001. As the result of these experiments was a series of (predictable) conclusions that are drastically limiting the possibilities of a strictly optimal control, we suggested an expert structure meant to lead to favorable sub-optimal work conditions, which are achievable in practice.