推进器饱和约束的水面无人艇固定时间精准跟踪控制

Fixed-time precision tracking control of an unmanned surface vehicle constrained by thruster saturations

中文关键词  无模型固定时间跟踪控制  非奇异终端滑模  有限时间观测器  推进器饱和  水面无人艇

英文关键词  model-free fixed-time tracking control  nonsingular terminal sliding-mode  finite-time observer  thruster saturations  unmanned surface vehicle

中文摘要

      针对复杂扰动、完全未知系统动态以及推进器饱和约束的水面无人艇高精度跟踪控制问题, 提出一种基于 固定时间非奇异终端滑模的无模型固定时间精准跟踪控制(MFPTC)方案. 首先, 设计有限时间集总观测器, 精确重 构和补偿集总未知项; 其次, 引入自适应辅助系统消除推进器饱和特性, 使得MFPTC方案在饱和约束下实现期望时 间内对预定轨迹的精准跟踪; 进而, 基于反正切函数构造固定时间幂次趋近律, 加快滑模变量收敛速度且有效削弱 控制抖振; 最后, 采用CyberShip II实验模型进行仿真研究, 结果验证所提出MFPTC 方案的有效性与优越性.

英文摘要

      In this paper, a model-free fixed-time precision tracking control (MFPTC) scheme based on the fixed-time nonsingular terminal sliding-mode (FNTSM) is proposed for high precision tracking control of an unmanned surface vehicle in the presence of complex disturbances, completely unknown system dynamics and thruster saturations. Firstly, a finitetime lump observer is designed to accurately observe and compensate for the lumped unknowns. Secondly, an adaptive assistant system is introduced to eliminate the saturation characteristics of the thrusters, so that the MFPTC scheme can achieve accurate tracking of the predefined trajectory in the desired time under the saturation constraint. And then, a fixedtime power reaching law is constructed based on the inverse tangent function, which can effectively weaken the controller chattering while speeding up the convergence of the sliding mode variables. Finally, the simulation studied on a prototype USV Cybership II shows remarkable efficiency and significant superiority of the proposed scheme.