Less-conservative robust adaptive control of neutral systems with mixed time-delays

In this paper, the problem of robust stabilisation of a class of neutral-type uncertain linear systems via adaptive control approach is investigated. The neutral systems are assumed to be subjected to model uncertainties, disturbances and mixed time-delays. In comparison to the previous work in the literature, with the assumption that the states of the system and the delayed-states of the system with its derivatives are completely accessible, a new and less-conservative robust adaptive control algorithm is proposed. Based on Lyapunov–Krasovskii function, the model uncertainties and the disturbances are compensated and the stability of the uncertain neutral-type system is guaranteed. The tracking problem via model reference adaptive control is also considered. The most important characteristic of the proposed approach is to make the overall system stability constraints depend on desired arbitrary matrices, and not on the practical system matrices. This is achieved by means of adaptation techniques. Finally, three illustrative examples with numerical simulations are carried out to indicate the significant improvements over some existing results.