Two-stage S-curve trajectory generation for time-optimal, anti-sway crane-rotation with jib-luffing and rope hoisting

This paper presents a trajectory generation method for rotary cranes that minimizes motion time while effectively suppressing load sway. A two-stage S-curve trajectory, derived from motion patterns observed in skilled operators was designed to suppress two-dimensional load sway attributed to inertial and centrifugal forces. The proposed method optimizes rotational angular velocity by incorporating nonlinear crane dynamics and actuator constraints, ensuring time-optimal control employing only jib rotation. The method is further generalized to accommodate multiaxial motions, including jib luffing and rope hoisting, thereby improving the adaptability. The trajectory was validated via simulations and laboratory-scale experiments, yielding residual load-sway angles below 0.006 rad with minimum motion time. The results demonstrate improved precision in load transport and reduced dependence on skilled operators. This study advances crane automation and operational safety in autonomous lifting systems. Future work will focus on full-scale implementation, real-world validation, and mitigation of mechanical stress induced by dynamic load swaying. • The validity of the nonlinear crane dynamic model is shown experimentally. • Two-stage S-curve trajectory is designed based on skilled operations. • Proposed trajectory is optimized considering nonlinear dynamics and constraints. • Simulation and experiments exhibit very small load-sway under rapid motion. • The method enables crane automation practically, which surpasses skilled operation.