Robust Sliding Mode Control of a Rotary Hook

Abstract Nowadays, boom cranes are highly automated machines with which numerous researches have been devoted to designing and implementing automatic controllers to suppress the residual vibrations during the payload transloading process. As an essential part of the boom crane system, rotary hook device plays an important role in adjusting the skew angle of the payload to match the skew angle of vessels or container trucks. However, at present, the rotary hook is still manually controlled by highly experienced and skilled crane operators because of its under-actuated characteristic. Therefore, in this paper, a robust Sliding Mode Controller (SMC) will be developed for an uncertain rotary hook system which can automatically drive the payload to desired angle whilst suppressing the residual skew oscillation caused by flexible ropes. The parametric uncertainties presenting in the system parameters will be thoroughly considered in the SMC design process. By conducting the sliding mode analysis, the constraints on the controller gains are formulated to ensure the robust stability of the closed-loop system. Moreover, a conventional Linear Quadratic Integral (LQI) controller will be introduced as a benchmark to compare with the robust SMC. All of conclusions will be drawn from both simulation and experimental results.