Skew control of a container crane

Abstract

This article describes the mathematical model of the 3-dimensional motions of a container crane used in the dockside of a container terminal. The container is suspended by four cables via a spreader. When the container is accelerated or affected by wind, the container will oscillate around horizontal axis (sway) or vertical axis (skew). And an accurate position control of the container is difficult to realize because of uncertain weight, inertial sway, and winds. This paper proposes a simple PID control of the skew motion based on the analysis of 3-dimensional dynamics of the container. This system uses four cylinders to increase and decrease forces in the individual cables so that the container can be affected by yaw torque to reduce the skew error. The simulation results show the effectiveness of the PID controller in controlling the skew motion in the presence of winds.

Modeling and control of overhead cranes: A tutorial overview and perspectives

“…The authors believe that the methods developed for the cable-driven robotic systems [267] may be useful to control the payload rotation in 3D space based on the kinematic developed in [166,40,165,16,40,15,123] if each cable's length can be controlled independently. Such a scenario has been addressed in [172,123] where the payload is suspended by four cables which can be adjusted separately by four actuators. Note that in [159,39,38], it can be seen that the considered system is quite similar to an OC.…”