Fixed-time Target-guided Coordinate Control of Unmanned Surface Vehicles Based on Dynamic Surface Control

Abstract

This paper presents an investigation on the target-guided coordinated control (TACC) of unmanned surface vehicles (USVs). In the scenario of tracking non-cooperative targets, the status information of the target can only be obtained by some USVs. In order to achieve semi-encirclement tracking of non-cooperative targets under maritime security conditions, a fixed-time tracking control method based on dynamic surface control (DSC) is proposed in this paper. Firstly, a novel TACC architecture with decoupled kinematic control law and decoupled kinetic control law was designed to reduce the complexity of control system design. Secondly, the proposed DSC-based target-guided kinematic control law including tracking points pre-allocation strategy and sigmoid artificial potential functions (SigAPFs) can avoid collisions during tracking process and optimize kinematic control output. Finally, a fixed-time TACC system was proposed to achieve fast convergence of kinematic and kinetics errors. The effectiveness of the proposed TACC approach in improving target tracking safety and reducing control output chattering was verified by simulation comparison results.

1. Introduction

The utilization and exploration of ocean resources and the escort of important shipping lanes have attracted full attention around the world [1]. In order to effectively protect maritime territory and cooperative targets from infringement, path-guided coordinate control [2−3], trajectory-guided coordinate control [4−5], target-guided coordinate control [6] and collaborative target surrounding [7−8] have become important working modes for multiple USVs. In particular, collaborative target tracking control technology of USVs has gained broad applications in formation escort, maritime patrol and intrusion target expulsion.

During the past few years, research on USVs TACC has made great progress. Fahimi [9] transformed the formation tracking problem into the virtual target tracking problem. By designing a sliding mode controller to track the position and heading of a virtual target, formation maintenance was achieved during the movement of USVs. Works on decentralized control for tracking a cooperative target was discussed in Refs. [10−13]. In Ref. [10], NN was developed to estimate model uncertainties and external environmental disturbance. Meanwhile, dynamic surface control technology was utilized in the kinematic control layer to smooth the kinetic control output chattering. To avoid actuator saturation, Khoshnam [11] introduced a generalized saturation function into the kinetic error and further used RBFNN based on Ref. [10] to accurately estimate internal and external disturbances. To address the problems of angle constraints and actuator faults, barrier Lyapunov functions (BLFs) were designed in Ref. [12], and the finite time convergence of the control system was achieved. Sun et al [13] developed a continuous function to replace the signum function in the sliding mode control method, which effectively reduced the chattering based on Ref. [9]. Different from those in Refs. [10−13], Liu et al [14] studied the problem of unavailable non-cooperative target velocity. An extended state observer (ESO) was designed in the kinematic control law to estimate the uncertain target dynamics due to the unavailable velocity.

However, the above studies are all based on decentralized control structures. Since there is no information exchange among USVs, the coordination is limited. This paper proposes a fixed-time TACC method based on dynamic surface control to achieve semi-encirclement tracking of non-cooperative targets, addressing the challenges of limited target information and ensuring fast convergence and collision avoidance.