A composite control method for industrial ship unloaders with time-varying rope length

In the design of unmanned ship unloaders, time-varying rope length and on-site sensor noises will bring great difficulties for anti-swing and positioning controls, which further affect the material-handling efficiency and safety. In this paper, a novel composite control method is proposed for industrial ship unloaders. Firstly, a discrete model of ship unloaders with variable rope length and damping coefficient was established. Secondly, an extended state extended Kalman filter (ESEKF) was proposed to solve the industrial sensor noises. Subsequently, an improved trajectory planning method using two-hump extra insensitive shaper (THEI) was proposed for anti-swing feedforward control. Moreover, a constrained model predictive control (MPC) with state error feedback was designed to deal with changes in rope length and other external disturbances. Lastly, both simulation and experimental results show that compared to typical methods, the proposed method has superior performance in terms of maximum load swing angle, residual swing angle, and positioning adjustment time, while also possessing anti-disturbance.