Cranes are one of the central equipments in industrial material handling as they play an important role in logistics and transportation. They are mainly in intermediary roles in logistics processes, providing effective means to reorganize materials by lifting, transporting and stacking up. There are different types of cranes used throughout various industries. Main types are overhead/gantry, tower and boom cranes. Gantry cranes have integrated mechanical structure with rigid leg and wheels rolling on translation tracks, whereas overhead cranes translate on runway beams. The fact that cranes are being underactuated systems and internal or external disturbances such as mechanical and electrical failures, high acceleration-deceleration rates, weather conditions and various unknown disturbances can cause abrupt motion during the transportation process, affecting the system stability by causing the load to swing, which is nonlinear in nature and in turn introduces serious problems such as mechanical wear, decrease in crane positioning capability, productivity and even personnel injuries. Many papers, introducing various open and closed loop control methods such as input shaping, command smoothing, fuzzy-logic, adaptive and robust control with different feedback elements such as vision feedback, inclinometer, accelerometer or encoder feedback to overcome this control problem are published.
In this study, first the dynamics model of gantry crane will be derived from the general laws of motion and Lagrangian energy analysis. Then, a proper disturbance rejecting robust sliding mode control mechanism with anti-sway system will be introduced and simulation results will be compared with traditional PID control methods. The controller and drive systems will be considered as one system as their outputs and feedback normalized for the controller.
Anahtar Kelimeler: System Dynamics, PID Control, Sliding Mode Control, Anti-Sway, Disturbance Rejection, Gantry Crane
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