LMI Approach to Robust Control of Rotary Cranes under Load Sway Frequency Variance

Abstract

Because horizontal motion of a rotary crane generates undesirable two-dimensional load sway, skillful operators are needed to control the crane's motion; for this purpose, various types of control schemes have been proposed. Because natural frequency of the rope-load oscillation system affects the stability and performance of the control system, the controller design should consider robustness with respect to rope length. If the control system considers the effect of rope length variance, the crane's motion can be controlled without a sensor system for measuring it. This paper presents a control method based on linear matrix inequality optimization for achieving robustness with respect to rope length variance. Numerical simulations and experimental results demonstrate the effectiveness of the proposed method.