An adaptive sliding mode controller with a new reaching law for tracking problem of an autonomous underwater vehicles

Abstract

Since autonomous underwater vehicles (AUVs) have highly nonlinear dynamics, the employed controller in these systems must be accurate and robust against noise and uncertainties. Sliding Mode Controller is very robust against both the parameters changing and external disturbance. But, there are some major drawbacks of these controllers such as chattering and high vulnerability against noise. In this paper, by modifying the reaching law and using an adaptive gain in the proposed sliding mode controller, these problems are eliminated from the input signal of the system. In the presented reaching law, a continuous term is used instead of the discrete sign function as well as the velocity term is entered in the reaching law. Since there are external disturbances, noises and uncertainties in the system dynamics and modeling, the states may be separated from the surface. Since the reaching law acts when the states separate from the sliding surface, then the gain of reaching law is adapted according to the uncertainties, states error and velocity. Also, the upper bound of disturbance and uncertainty are estimated. Furthermore, the reaching condition and limitation of the switching variable rate for the proposed controller are investigated. Finally, stability and convergence of the closed-loop system are proven analytically using the Lyapunov stability theorem. Some simulations and comparisons with other methods show efficiency of the presented method.

A finite-time adaptive sliding mode control based on DOB for AUVs subject to matched and mismatched disturbances

“…Control of autonomous underwater vehicles (AUVs) is an interesting topic which has been studied broadly in the literature (Chen et al, 2016; Elmokadem et al, 2016; Liu et al, 2017; Ramezani-al and Tavanaei-Sereshki, 2019a, 2019b; Xu et al, 2015; Yan and Wang, 2012; Yu et al, 2012). This topic is a challenging task due to inherent nonlinear and time-varying dynamics of AUVs.…”

“…One of the ways to overcome the SMC chattering is using a proper reaching law which has first been introduced by Hung et al (1993). Designing reaching laws have been subject of many articles (Bartoszewicz, 2015; Fallaha et al, 2011; Ma et al, 2017; Mozayan et al, 2016; Ramezani-al and Tavanaei-Sereshki, 2019a, 2019b). One of the reaching laws reported in the literature is the exponential reaching law (Ma et al, 2017).…”

“…In Mozayan et al (2016), an exponential reaching law has been used to reduce the chattering phenomenon in the control input. In Ramezani-al and Tavanaei-Sereshki (2019b) by modifying the reaching law and using an adaptive gain, the chattering and a high vulnerability against noise problems are eliminated from the input signal of the system. The results of Ramezani-al and Tavanaei-Sereshki (2019b) on the tracking of an AUV have been compared with the reaching laws reported in Fallaha et al (2011) and Mozayan et al (2016).…”

Adaptive nonlinear control of an autonomous underwater vehicle

“…Much effort has been focused on areas of system identification, modeling and control algorithms to enhance the autonomy of such devices. Therefore, several control methods including sliding mode control (Ashrafiuon et al, 2008; Elmokadem et al, 2016; Healey and Lienard, 1993), terminal sliding mode control (Elmokadem et al, 2017), higher order sliding mode (Joe et al, 2014), adaptive control (Sahu and Subudhi, 2014; Ramezani-al and Tavanaei-Sereshki, 2018), neural network control (Yuh, 1990) and back stepping control (Liang et al, 2016) have been proposed.…”

Modeling and implementation of 1-D inverted magnetic needle system using a robust sliding mode controller

“…In Bartoszewicz (2015), the authors proposed a new reaching law for SMC controller of nominal continuous system. Ramezani-al and Tavanaei-Sereshki (2019) proposed a modified reaching law with an adaptive gain, for tracking error to zero, in the presence of disturbance, noise, and uncertainties for an autonomous underwater vehicles (AUVs).…”