Improved unity magnitude input shaping scheme for sway control of an underactuated 3D overhead crane with hoisting

•We propose an improved unity magnitude input shaping (UMZV) for control of a 3D overhead crane.•The technique can adapt to the changes in the cable length for efficient sway control.•The shaper achieves significant reductions in maximum transient and residual sways.•Experiments verify the superiority of the improved UMZV shaper. This paper proposes an improved unity magnitude zero vibration (UMZV) shaper for payload sway reduction of an underactuated 3D overhead crane with hoisting effects. The proposed technique is effective in adapting to changes in the cable length and the crane dynamics during hoisting and thus provides higher sway reductions. The shaper is designed using the relationship of optimal UMZV shaper parameters and cable length obtained using a nonlinear model of a 3D overhead crane and particle swarm optimisation. A technique to choose the shaper parameters automatically during the hoisting operation is designed. To test the effectiveness of the proposed technique, MATLAB simulation and experiments are carried out on a laboratory crane under two hoisting cases. The superiority of the proposed technique is confirmed by achieving at least two-fold reductions in maximum transient and residual sways of the laboratory crane when compared to the Average Travel Length technique. The advantage of the improved UMZV shaper is also demonstrated with the simulation results. It is envisaged that the method can be useful for an operator to handle cranes in three dimensions without motion-induced sway problem.