Wave Based Robust Control of a Crane System

In this paper we propose a robust control strategy for a gantry crane system with hoisting. The trolley moves horizontally to translate a load mass, hanging at the lower end of a cable, from rest to rest. Due to the flexibility of the cable, load swing easily arises, and should be controlled. To this end, the trolley motion and load hoisting are designed carefully. The desired trolley motion is decided in real time by a wave-based approach, which interprets the cable motion as two superposed traveling waves, to eliminate the load swing at the end of a manoeuvre. The load hoisting is chosen to reduce the load swing during the manoeuvre. A robust algorithm, based on a nonlinear model of the crane system, is proposed for the tracking control, allowing for system parameter variations and uncertainties. This control algorithm works very well and is stable and robust to large load variations. As demonstrated in the numerical simulations, it lands the load rapidly and exactly at target and stops it dead, with zero swing