An embedded structure of model reference adaptive system

The traditional model reference adaptive system (MRAS) is of parallel configuration. By representing the reference model as an equivalent closed-loop subsystem, these two subsystems can share a controller virtually. An embedded structure of MRAS is thereby presented. In this paper, two approaches are developed for designing the adaptive laws. The adaptive law based on Lyapunov stability theory is designed for low-order systems. The adaptive law based on the recursive least-square (RLS) algorithm is suitable for both low- and high-order systems. The RLS-based adaptive law provides a quick convergence rate for the controller adaption. MRAS with RLS-based adaptation law performs better in trajectory tracking and model following. Simulation results show the effectiveness of the proposed method.