Adaptive Event-Triggered Control Strategy for Ensuring Predefined Three-Dimensional Tracking Performance of Uncertain Nonlinear Underactuated Underwater Vehicles

Abstract

This paper presents an adaptive event-triggered control strategy for guaranteeing predefined tracking performance of uncertain nonlinear underactuated underwater vehicles (UUVs) in the three-dimensional space. Compared with the related results in the literature, the main contribution of this paper is to develop a nonlinear error transformation approach for ensuring predefined three-dimensional tracking performance under the underactuated property of 6-DOF UUVs and limited network resources. A nonlinear tracking error function is designed using a linear velocity rotation matrix and a time-varying performance function. An adaptive event-triggered control scheme using the nonlinear tracking error function and neural networks is constructed to ensure the practical stability of the closed-loop system with predefined three-dimensional tracking performance. In the proposed control scheme, auxiliary stabilizing signals are designed to resolve the underactuated problem of UUVs. Simulation results are presented to illustrate the effectiveness of the theoretical methodology.

Nonlinear-Observer-Based Design Approach for Adaptive Event-Driven Tracking of Uncertain Underactuated Underwater Vehicles

“…In this work, the underacutated control vector η is intermittently updated according to the triggering law to be derived later. The nonlinearities M, D, and B in the dynamics of the UUV are taken from the definitions reported in [23,30,31]. The structure of the neutrally buoyant UUV concerned in this study is depicted in Figure 1.…”

“…Thus, an adaptive velocity observer design strategy using state transformation and neural networks is proposed to estimate the velocity information of UUVs while compensating for the unknown system nonlinearities, where adaptive laws based on a scaling function are derived to learn weights of neural networks. (ii) Compared with the existing event-triggered control results for three-dimensional tracking [23,28], this study establishes the design methodology of the guaranteedperformance-based adaptive tracker and its event-triggering condition depending on only the position measurement of 6-DOF UUVs. Then, the stability of the proposed output-feedback event-triggered tracking system is analyzed in the Lyapunov sense.…”

“…In [22], an adaptive region tracking control problem with prescribed transient performance was addressed fully-actuated 6-DOF underwater vehicles with thruster fault. An event-triggered neural network tracking control design with predefined performance was developed for uncertain 6-DOF UUVs [23]. Despite these successful results, full state measurements are required in the aforementioned tracking designs, that is, all positions and velocities of underwater vehicles should be measured online.…”

“…Besides, the continuously updated tracking laws reported in [24][25][26][27] cannot be efficiently operated in the network-based underwater environment with low propagation speed, capacity-limited bandwidth and high energy consumption. To manage the transmission signal data economically, some limited studies have tried to deal with the event-triggered full state-feedback design problems for the depth control of underwater vehicles [28] and the prescribed performance control of 6-DOF UUVs [23]. Although these results [23,28] provide some remedies on the event-triggered tracking problems of underwater vehicles, they require the measurement of all state variables of underwater vehicles.…”

“…To manage the transmission signal data economically, some limited studies have tried to deal with the event-triggered full state-feedback design problems for the depth control of underwater vehicles [28] and the prescribed performance control of 6-DOF UUVs [23]. Although these results [23,28] provide some remedies on the event-triggered tracking problems of underwater vehicles, they require the measurement of all state variables of underwater vehicles. To the best of our observations, there is no systematic solution available for the output-feedback event-triggered tracking of uncertain 6-DOF UUVs.…”