Design Robust Controllers of Convey-Crane System under Different Types of Uncertainty

In this paper, the designing of robust controllers for well-known convey crane systems in the presence of uncertainties is presented. Cranes play a great role in the industrial environment, construction sites, ship-yard, and rial-yard because of their efficiency and accuracy in moving heavy and dangerous materials from one loading location to another. The main challenge in controlling such kinds of systems is to minimize the undesirable swings when different payloads are carried. This phenomenon is because the convey crane is classified as an under actuated nonlinear system and there are many sources of uncertainties that affect the plant of the physical system Hence, the stability of the convey crane system in the presence of the uncertainties became a challenging task between the researchers in the control engineering field and used as a benchmark in universities. In this research, firstly, the stability of the linearized model of the convey-crane system is analyzed using the edge theorem in the presence of two uncertain parameters: the rope length and the weight of the load, where the classical pole placement technique is used for stabilization purposes. Secondly, the sliding mode control (SMC) is proposed in order to stabilize the nonlinear model of the convey-crane system with the presence of noise signals. In order to test the effectiveness of the proposed SMC controller, a conventional PID control is applied to the linearized model of the convey-crane system, where the PID parameters are tuned using the well-known Ziegler-Nicholas method. The robustness against the uncertainties in the parameters of the convey crane is achieved by using the Edge theorem, whereas the robustness against the noise signal is tested by using MATLAB; the simulation results show the superiority of the SMC controller over the PID.