Combined disturbance observer-based fuzzy finite-time preassigned performance control for state-constrained nonlinear systems

This paper studies a fuzzy finite-time preassigned performance control challenge for state-constrained non-strict feedback nonlinear systems (NSFNSs) subject to input saturation and unmatched disturbances. By incorporating barrier Lyapunov function (BLF) with finite-time performance function, a new type of preassigned performance BLF is devised to address the issues of state constraints and achieve preassigned performance metrics (PPMs). Moreover, to address the design problem for NSFNSs and estimate unmatched disturbances, a combined nonlinear disturbances observer is developed. Additionally, a command-filter backstepping method is employed in the finite-time control scheme, thereby reducing the conservativeness of the assumptions on the desired signal. With stability analyses, all control aims can be completely acquired. The proposed approach is validated through two simulation examples.