A novel adaptive sliding mode controller design for tracking problem of an AUV in the horizontal plane

Abstract

Sliding Mode Controllers are very resistant against parameter alterations and external disturbances. However, major drawbacks of such controllers are chattering and high vulnerability to noise. In this paper, a novel reaching law for sliding mode controllers with an adaptive gain is proposed which eliminates the aforementioned drawbacks from the input signal of the system. In the proposed reaching law, a continuous term is used instead of a discrete traditional sign function. A large gain for the sliding mode is needed to satisfy the reaching condition, and a small gain for the sliding mode is needed to avoid the chattering phenomenon. To overcome this problem an adaptive gain has been incorporated into the proposed controller which adapts based on the variation of the sliding surface. The proposed controller with the new reaching law not only drives the system trajectory to the desired trajectory, but also it guarantees the time reaching is limited. The performance of the proposed controller demonstrates its superiority against the previous methods reported in the literature. Additionally, the proposed controller is not vulnerable to the applied noise. Simulation results show efficiency of the proposed controller.