Control Design for Overhead Crane with Variable Cable Length

Abstract

Although overhead crane systems play a vital role in industrial operations, their control remains challenging due to underactuated, strong dynamic coupling, and payload oscillations. Existing approaches have shown effectiveness in reducing oscillations but often struggle with external disturbances, parameter variations, and the complexities of tuning. Moreover, many previous studies assume constant payload vibration frequencies, whereas real-world operations frequently involve varying rope lengths, leading to frequency changes and reduced controller performance. To overcome these limitations, this paper proposes a dual control framework: a proportional-derivative and sliding mode control (PD-SMC) strategy for trolley positioning and payload swing suppression, combined with an active disturbance rejection control (ADRC) scheme for cable length regulation. The PD-SMC ensures accurate and robust motion control under disturbances, while ADRC provides fast tracking performance with reduced modeling dependency. Simulation results validate that the proposed approach achieves precise positioning and effective swing suppression, even under varying rope lengths.