Positioning and antiswing control of overhead crane systems: A supervisory scheme

Abstract

Overhead crane, as a common handling mechanical equipment, plays an irreplaceable role in modern industry. To ensure its efficient and reliable running, there is an urgent need to develop advanced control strategies. In this paper, a novel supervisory control scheme is proposed for overhead crane systems. The scheme involves a high-level decision making mechanism, called a supervisor, to evaluate which controller is suitable at the current instant of time among a family of candidate controllers. Detailedly, for all possible payloads, a multi-estimator is first introduced to achieve the appropriate estimations of trolley position, trolley velocity, payload angle and angular velocity. Then, based on the estimator signals, a family of candidate controllers are designed, each of which is workable for a certain payload. Finally, by constructing monitoring signals and online evaluating the values of the signals under different candidate controllers, the controller corresponding to the minimum value of the signals is applied to the system at the current instant of time. Under the proposed supervisory controller, the payload can be driven to the desired position, and meanwhile the swing of the payload is eliminated. Remarkably, uncertainties dynamical compensation and performance online evaluation mechanisms are included in the scheme, which endows the scheme powerful ability to suppress payload mass uncertainties, to guarantee fast setting-time, and to achieve online estimation of the payload masses. The simulation and experimental results show better workability of the proposed supervisory control scheme in application, including strong robustness, fast setting-time, accurate payload mass estimation, and convenient parameter selection.