Comparison of Extrainsensitive Input Shaping and Swing-Angle-Estimation-Based Slew Control Approaches for a Tower Crane

Abstract

Tower cranes are needed to move heavy objects safely around construction sites. In tower cranes, payload oscillations are a typical problem that can cause safety issues, especially if the crane is not operated by an experienced user. Depending on the system, there are different causes for oscillations, e.g., inertial forces from the crane movement or external forces, such as weather conditions. Hence, the selected control law for input tracking plays an important role to limit the oscillatory motion and to help the crane operator to prevent unwanted operations. In this paper, we study the slew control of a tower crane application from the viewpoint of reducing payload oscillations. Two different approaches are studied: open-loop control based on extrainsensitive input shaping and closed-loop swing angle control, based on the estimation of the hoist cable angle. The proposed control approaches are validated by running the developed control program against a multibody mechanics simulator containing a model of a Liebherr tower crane. The studied control laws are also evaluated using an experimental setup, which consists of a two-axis manipulator, inverters, and a programmable logic controller in which the studied control methods are implemented. The results from the multibody dynamics simulations and from the experimental setup are presented and evaluated from the viewpoint of crane operation.

Keywords

• input shaping
• payload oscillations
• swing angle estimation
• slew control
• tower crane