Enhanced-coupling adaptive control for double-pendulum overhead cranes with payload hoisting and lowering

Overhead cranes, which have been extensively studied, are mostly simplified as single pendulums. However, in practice, the existence of lifting hook usually makes the crane present double-pendulum swing, i.e., hook swing with respect to the trolley and payload swing with respect to the hook. Therefore, a severe gap between theory and practice is generated. Due to this fact, lots of researchers are now working on the automation for double-pendulum overhead cranes (DPOC). However, with an extra unactuated degree of freedom, the control of DPOC is much more challenging than that of the simplified system due to its complicated dynamics, which is made even worse when considering payload hoisting/lowering and uncertain system parameters. To solve this problem, an enhanced-coupling adaptive controller is proposed for DPOC in this paper. Specifically, the payload hoisting/lowering motion is elaborately considered. Moreover, to improve the swing suppression performance, more swing information are incorporated into the construction of control inputs. Particularly, the uncertain payload mass is online estimated by a new adaption law ensuring precise identification, which further enhances the robustness of the proposed method. By utilizing Lyapunov techniques and LaSalle's Invariance Theorem, the closed-loop system is proven to be asymptotically stable around the desired equilibria. Finally, convincing hardware experimental results are presented to demonstrate the efficiency and superior control performance of the proposed method. (C) 2018 Elsevier Ltd. All rights reserved.