Introduction

Abstract

This chapter provides a brief summary of the recent advancements made in model-reference adaptive control theory. Adaptive control is a promising technology that can improve the performance of control systems in the presence of uncertainty due to a variety of factors such as degradation and modeling uncertainty. During the past decade, the adaptive control research community has produced several advancements in adaptive control theory along with many novel adaptive control methods as a result of the increased government research funding. Many of these new adaptive control methods have added new capabilities in terms of improved performance and robustness that further increase the viability of model-reference adaptive control as a future technology. Flight test validation of adaptive control on full-scale aircraft and unmanned arial vehicles has increased the confidence in model-reference adaptive control as a possible new flight control technology for aerospace vehicles in the near future. In spite of the five decades of research in adaptive control, the fact still remains that currently no adaptive control system has ever been deployed on any safety-critical or human-rated production systems. Many technical problems remain unresolved. As a nonlinear control method, the lack of well-accepted metrics for adaptive control system design presents a major hurdle for certification. The development of certifiable adaptive control systems is viewed as a major technical challenge for the adaptive control research community to address in the current research.