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A Minimum-Time Motion Online Planning Method for Underactuated Overhead Crane Systems

In this paper, a minimum-time motion online planning (MTMOLP) method is proposed for underactuated overhead crane systems within both safety and physical constraints. First, the motion process is divided into seven stages by analyzing the coupling between trolley movement and payload swing, and a minimum-time motion planning problem and the expression of its solution are presented. Second, a state prediction method based on the payload swing energy is given to compute the solution of the motion planning problem in real time. Finally, several simulations and experiments are conducted to verify the feasibility and effectiveness of the proposed method. The results show that the MTMOLP method can obtain the solution of the minimum-time motion planning problem with spending very little time on the computing process. Therefore, it can be applied to the online motion planning of the overhead cranes. Furthermore, the motion process division by the coupling analysis can also provide a reference for the underactuated control of overhead crane systems.