Adaptive Control for Nonlinear Systems With Discontinuous Tracking and Output Constraint Within Predefined Time Interval

This brief investigates the problem of adaptive tracking control for uncertain nonlinear systems with output constraint in predefined time interval. The considered constraint brings the problem of discontinuity in the transition between constrained and unconstrained phases. Firstly, a novel shifting function is proposed to solve this problem. Then, this shifting function is combined with the barrier Lyapunov function (BLF) to solve the considered output constraint. By means of variant Sigmoid functions, the requirement of the reference signal is relaxed, which only needs to be piecewise differentiable. The proposed control method is also able to deal with the constraint-free case, the infinite-time constrained one and deferred output constraint with unchanged control structure. Finally, the effectiveness of the proposed control strategy is assessed through the simulation.