Adaptive HJI Sliding Mode Control Of Three Dimensional Overhead Cranes

As important equipment of modern production, overhead cranes are mainly used for loading and unloading, transmitting cargos and improving labor productivity. The synthesis of feedback control for overhead cranes remains a challenge since the overhead crane system is under-actuated where the control inputs are lower than that of the number of degrees of freedom. Suspended cargos in overhead crane system are caused to swing without good control strategies and due to the disturbances by open conditions, which can make inaccurate motions of crane mechanisms and the unsafe situation in operation zones. Therefore, it is crucial for overhead crane systems to satisfy rigorous requirements in terms of safety and efficiency.Due to the restrictions of the actuator, the control inputs are usually bounded by a known constant, and it is difficult to achieve large control signals. Besides, the presences of uncertainties and disturbances may cause poor qualities of the controller in operating environment. Therefore, input saturation and robustness of the system are the problems to be solved in this paper.In this dissertation, an adaptive HJI sliding mode controller is developed for the model of 3D overhead cranes in case of actuator constraint and the presences of disturbances. The proposed controller can simultaneously execute the duties consisted of keeping the payload swings small during the transport process and absolutely suppressing the cargo vibrations at destinations of trolley and bridge even in an extremely complicated operation with uncertain system parameters. Robust control performances based on RBF neutral networks are obtained when the system is subject to disturbances. The simulation results indicate the effectiveness of the proposed control method.To summarize, the combination of RBF neural network and HJI sliding mode theory can effectively solve the problem of input saturation and improve the robustness of the system. In order to improve the control accuracy and eliminate the swing of the cargos, the high order sliding mode control theory is applied to the controller. Second order sliding mode control is continuous in time domain which leads to the elimination of the swing and keep the robustness of the system. It has great potentials.