Command-Filter-Based Adaptive Fuzzy Finite-Time Output Feedback Control for State-Constrained Nonlinear Systems With Input Saturation

In this article, an adaptive fuzzy finite-time tracking control method is investigated for a class of state-constrained nontriangular nonlinear systems with input saturation. First, the fuzzy logic system is introduced to process the unknown functions, and the immeasurable system states are estimated accurately via the fuzzy state observer. To handle the saturation nonlinearity, the function approximation method is applied for the system transformation. Second, the "explosion of complexity" problem inherent in backstepping is solved through the command filter. Meanwhile, the barrier Lyapunov function is designed to guarantee that the constraints of states are not violated. Third, an adaptive fuzzy finite-time output feedback controller is developed to render the closed-loop system semiglobally practically finite-time stable. Eventually, simulation examples are included to illustrate the effectiveness of the theoretical results.