Adaptive Interval Type-2 Fuzzy Fixed-time Control for Underwater Walking Robot with Error Constraints and Actuator Faults Using Prescribed Performance Terminal Sliding-mode Surfaces

Abstract

Underwater walking robot (UWR) is a kind of autonomous underwater vehicles which can walk underwater. In this work, the fixed-time tracking control problem of UWR with external disturbances, error constraints, and actuator faults is investigated. An interval type-2 fuzzy neural network approximator is designed to tackle nonlinear uncertainties, and a novel prescribed performance terminal sliding-mode surface is proposed to handle error constraints. Furthermore, two fault-tolerant controllers are given, where one is nonsingular and the other has higher steady-state precision. According to Lyapunov theory, the proposed controllers can guarantee that system states will converge to the expected values in a fixed time. Simulation results demonstrate the effectiveness of the proposed control strategies.