Novel robust adaptive control scheme using non-quadratic Lyapunov functions for higher order systems

In literature, design of model reference adaptive control (MRAC) schemes and adaptive laws has always been developed based on Lyapunov stability theory. Over the past few decades, it has been a common practice to use Quadratic Lyapunov Functions (QLFs). In contrast to such development and as a continuation to the research effort earlier published by the same authors, this paper involves the use of Non-Quadratic Lyapunov Functions (NQLFs) for higher order systems. These new laws have the same advantage of assuring the stability of the overall system as well as improving the overall system performance whether in the absence or presence of disturbance. This improvement is considered in the fast and better convergence of the system output error signal while going to zero. Finally, this paper presents simulation results supporting the arguments.