Adaptive Fuzzy Sliding Mode Control for Gimbal System Bbased on Super Twisting Sliding Mode Observer

In this paper, an adaptive fuzzy sliding mode control based on observer is presented to control the position of the two-axis gimbal system in the presence of the dynamics of DC motors. At first, a super twisting sliding mode observer is designed to access the position and speed information of joints of the gimbal system. Then, due to the presence of structured and unstructured uncertainties in the dynamical equations of the gimbal system and its actuators, a sliding mode control for position control is used. Due to the presence of the sign function in the control input, the occurrence of undesirable chattering phenomenon in the control input is inevitable. Therefore, in the following, an adaptive fuzzy approximator is designed, which eliminates the chattering phenomenon in the control input and reduces its amplitude. The mathematical proof shows that the closed loop system with the proposed control and in the presence of the existing uncertainties has a global asymptotic stability. In order to investigate the proposed control performance, three-stage simulations were implemented on a two-axis gimbal system. The results of the simulations show the desired performance of the observer and the proposed control.