Trajectory Tracking of a Quadrotor for Obstacle Avoidance Using Super-Twisting Sliding Mode Controller and Observer

Sliding mode control is one of the most common types robust control that can compensate the model structure and parametric uncertainties, but the main disadvantage of this method is chattering phenomenon. Although a boundary layer around the sliding surface can eliminate chattering effect, it reduces tracking performance and robustness in control. The second generation of sliding mode control called Second Order Sliding Modes (SOSM) is a solution to this problem. Super-Twisting Sliding Mode (STSM) is a modified SOSM control that reduces chattering effect naturally and without a defined boundary layer, while maintaining the robustness of the Conventional Sliding Mode (CSM) control. In this paper, the problem trajectory planning is solved in an environment with fixed obstacles by using firefly optimization algorithm and polynomial trajectories, then STSM control is designed for quadrotor in the presence of uncertainties to tracking path trajectory and the performance of this controller is compared against Feedback Linearization (FL) and CSM control. Also, derivative of some of the states calculates by using super-twisting observer in the closed loop control and stabilization while there is no direct access to them through the sensors.