Liu Yan-Jun, Gong Mingzhe, Liu Lei, Tong Shaocheng, Chen C L Philip
IEEE Trans Cybern. 2021 Mar;51(3):1380-1389. doi: 10.1109/TCYB.2019.2933700. Epub 2021 Feb 17.
This article presents an adaptive output feedback approach of nonlinear multi-input-multi-output (MIMO) systems with time-varying state constraints and unmeasured states. An adaptive approximator is designed to approximate the unknown nonlinear functions existing in the state-constrained systems with immeasurable states. To deal with the tracking problem of such systems, a state observer with time-varying barrier Lyapunov functions (BLFs) is introduced in the controller design procedure. The backstepping design with time-varying BLFs is utilized to guarantee that all system states remain within the time-varying-constrained interval. The constant constraint is only the special case of the time-varying constraint which is more general in the real systems. The proposed control approach guarantees that all signals in the closed-loop systems are bounded and the tracking errors converge to a bounded compact set, and time-varying full-state constraints are never violated. A simulation example is given to confirm the feasibility of the presented control approach in this article.
本文提出了一种具有时变状态约束和不可测状态的非线性多输入多输出（MIMO）系统的自适应输出反馈方法。设计了一种自适应逼近器，用于逼近存在不可测状态的状态约束系统中的未知非线性函数。为了解决此类系统的跟踪问题，在控制器设计过程中引入了具有时变障碍Lyapunov函数（BLF）的状态观测器。利用具有时变BLF的反步设计，以确保所有系统状态保持在时变约束区间内。常数约束只是时变约束的特殊情况，而时变约束在实际系统中更为普遍。所提出的控制方法保证了闭环系统中的所有信号都是有界的，跟踪误差收敛到一个有界紧致集，并且时变全状态约束永远不会被违反。给出了一个仿真例子，以证实本文所提出控制方法的可行性。
