Practical fixed-time output tracking control for a class of switched nonlinear systems with prescribed error constraints

In this paper, the problem of practical fixed-time output tracking control for a class of switched nonlinear systems with prescribed constraints imposed on tracking error has been investigated. First, to make system output follow the reference signal/trajectory within a safe margin, a tangent-type barrier Lyapunov function (tan-type BLF), which degenerates to a normal form when the tracking error constraint vanishes, is constructed intentionally to cope with the tracking error constraints implicitly. Then a practical fixed-time output tracking control scheme for the switched nonlinear systems is established with remoulding the technique called adding a power integrator (AAPI). Moreover, the upper bound of settling time is only related to the specific parameters to be designed, that is, it does not depend on the initial state of switched systems. A technical innovation of the proposed scheme lies in its unified characteristics, allowing the designed practical fixed-time output tracking stabilisers work effectively for the cases both with and without prescribed tracking error constraints without necessitating to change their structure. Simulations are presented to demonstrate the effectiveness of the proposed method.