Optimal Control of Payload's Skew Rotation in Crane Systems with State and Control Input Constraints

In this paper, a nonlinear sub-optimal time control is proposed as a vibration controller for the payload's skew rotation process of crane systems. Physical constraints of the actuator including bounded velocity and bounded acceleration are explicitly taken into account in the design process. Clipping-off conjugate gradient method is adopted to solve the bounded optimal control problem, whereas penalty function is employed to relax the state constraint. Both simulation and experimental results are provided to clarify the effectiveness of the optimal control system. The proposed scheme can be directly applied to transfer the payload to desirable skew orientation without any residual oscillation, or it can be utilized as a reference trajectory planner of the skewing control module for a 2-DOFs controller in either overhead or rotary crane systems.