Online Antiswing Trajectory Planning for a Practical Rubber Tire Container Gantry Crane

Rubber tire container gantry cranes (RTG) are the most commonly used equipments to stack containers in ports. With four sets of ropes hoisting the cargo, the system dynamics become much more complicated and unpredictable when compared with traditional gantry cranes, which imposes higher requirements to the skills of operators. During the delivering process, large sway motion of the container is often excited by inappropriate manual operations, which badly impairs efficiency and safety. This issue is made even worse when considering the elasticity of rubber tire, wind disturbances, and many other practical disturbances. To improve the working efficiency of ports, an automatic antiswing trajectory planning method is proposed for RTG in this article. Specifically, reference trajectories are first generated to ensure that the trolley/rope accurately reach the desired position. After that, appropriate feedback terms are incorporated to online optimize the trajectories, so that the container swing motion is sufficiently suppressed even under unfavorable conditions. Lyapunov-based analysis is presented to guarantee the correctness of our conclusion. Furthermore, extensive hardware experiments on a practical RTG are performed to demonstrate the efficiency of the proposed method. To our best knowledge, with concise structure and superior antiswing ability, the proposed method is one of the very few methods which can be successfully applied to the practical RTG systems.