Adaptive Terminal Sliding Mode NDO-Based Control of Underactuated AUV in Vertical Plane

Wei Chen,Yanhui Wei,Jianhui Zeng,Han Han,Xianqiang Jia

doi:10.1155/2016/6590517

Abstract

The depth tracking issue of underactuated autonomous underwater vehicle (AUV) in vertical plane is addressed in this paper. Considering the complicated dynamics and kinematics model for underactuated AUV, a more simplified model is obtained based on assumptions. Then a nonlinear disturbance observer (NDO) is presented to estimate the external disturbance acting on AUV, and an adaptive terminal sliding mode control (ATSMC) based on NDO is applied to enhance the depth tracking performance of underactuated AUV considering both internal and external disturbance. Compared with the traditional sliding mode controller, the static error and chattering problem of the depth tracking process have been clearly improved by adopting NDO-based ATSMC. The stability of control system is proven to be guaranteed according to Lyapunov theory. In the end, simulation results imply that the proposed controller owns strong robustness and satisfied control effectiveness in comparison with the traditional controller.

Highlights

Autonomous underwater vehicle (AUV) is a kind of underwater vehicles with onboard power supply and intelligence
An adaptive sliding mode controller based on nonlinear disturbance observer (NDO) is introduced to solve the depth tracking problems of autonomous underwater vehicle (AUV)
− sin θ + Muuu2δs + Dout, where Iyy is the inertial movement of AUV about the pitch axis yB, m is the mass of AUV, are the coordinates of AUV’s mass center and buoyancy center, respectively, in the body-fixed frame oB-xByBzB, z is the diving depth of AUV in the frame oE-xEyEzE, Weig is the weight of AUV, Buo is the buoyancy of AUV in the water, Dout is the disturbance from the outside environment, δs is the rudder input, Muu, Zuu are the coefficients of rudder, and Zẇ, Zq, Zuq, Zuw, Zw|w|, Zq|q|, Mq, Mẇ, Muq, Muw, Mw|w|, Mq|q| are the hydrodynamics coefficients of AUV

Summary

Introduction

Autonomous underwater vehicle (AUV) is a kind of underwater vehicles with onboard power supply and intelligence. Antonelli et al [18] proposed an adaptive controller for ODIN AUV; Yu et al [19] used adaptive technique on the basis of neural networks to control AUV; Zhang et al [20] constructed an adaptive output feedback controller combined with DRFNN method to realize the tracking control target of AUV Disturbance is another key factor which affects AUV, and it is always unpredictable, nonperiodic, and even highly nonlinear. An adaptive sliding mode controller based on NDO is introduced to solve the depth tracking problems of AUV. The simulation experiments verify the effectiveness of the proposed controller, and the robustness of underactuated AUV’s depth tracking in the vertical plane is shown in the case of external disturbance

Mathematical Model of Underactuated AUV

Terminal Sliding Mode Control Based on NDO

Simulation Experiment

Conclusion