Gain margins of model reference adaptive control systems

This paper studies the gain margins of model reference adaptive control (MRAC)systems: the range of a control gain in a designed adaptive control system, which is sufficient for closed-loop signal boundedness and asymptotic tracking. Analytical results are obtained for four MRAC schemes: direct and indirect, continuous-time and discrete-time, applied to single-input single-output LTI systems. Simulation results are presented to illustrate some of the results.