The problem of optimal control of a system trolley - payload has been studied in the article. A criterion for the problem was the duration of the trolley acceleration. The problem has been stated in the closed-loop form. It provided the feature of elimination of external disturbances. The control constraints were non-symmetrical. It allowed for utilizing a crane drive in soft-control mode. The problem has been solved for rest initial state of the system. In order to find problem solution modified particle swarm optimization method has been used. © 2019, Politechnica University of Bucharest. All rights reserved.