SIMPLE ADAPTIVE CONTROL - A STABLE DIRECT MODEL REFERENCE ADAPTIVE CONTROL METHODOLOGY - BRIEF SURVEY

In spite of successful proofs of stability and even successful demonstrations of performance, the use of Model Reference Adaptive Control (MRAC) methodologies in practical real world systems has met a rather strong resistance from practitioners and has remained very limited. Apparently, the practitioners have a hard time understanding the conditions for stable operations of adaptive control systems under realistic operational environments. Besides, it is difficult to measure the robustness of adaptive control system stability when compared with the common measure of phase margin and gain margin that is utilized by present, mainly LTI, controllers. This paper attempts to revisit the fundamental qualities of the common gradient-based MRAC methodology and to show that some of its basic drawbacks have been addressed and eliminated within the so-called Simple Adaptive Control methodology. Sufficient conditions that guarantee stability are clearly stated and lead to similarly clear proofs of stability and to successful and stable applications of SAC.