未知不确定非线性系统的直接自校正滑模控制

针对一类具有未知不确定性的非线性系统,提出一种参数直接自校正滑模控制方法.将系统的非线性、参数变化和外部干扰都视作系统不确定性,控制器的设计无需不确定项的上下界等信息:为改善跟踪性能与减小输入抖振,控制器设计中引入可调边界层厚度的双极性sigmoid函数与可变滑模切换增益,推导出控制增益和边界层厚度的直接自校正律,并基于Lyapunov判据给出了闭环系统稳定性证明.仿真实例证明了该方法的有效性和正确性.

Sliding mode control with direct self-tuning for a class of nonlinear system with unknown uncertainties

Based on the combination of the direct adaptive control and the sliding-mode control, we present a new robust tracking controller for a class of nonlinear systems with unknown uncertainties. The controller treats the nonlinearity, the parametric uncertainties and the external disturbances as the system uncertainties. Without the boundaries and other information of the uncertainties, the controller and the self-tuning laws for the parameters are designed by using the Lyapunov stability theory. The closed-loop system is robust and asymptotically stable in the sense of the Lyapunov stability. The state trajectories can reach the sliding mode within finite time, eliminating the control input chattering thereafter. Simulation results are presented to verify the feasibility and correctness of the proposed control scheme.