Model Reference Adaptive Control Systems: Background and Development

• Main Author: M. L. Tatnall
• Format: Article
• Language: English
• Published: SAGE Publishing 1977-12-01
• Series: Measurement + Control
• Online Access: https://doi.org/10.1177/002029407701001202

Of the many classes of adaptive control systems described in the literature this article is primarily concerned with the background and development of the model reference type. Of this large group the main emphasis is upon systems synthesised by the use of stability criteria. The relatively recent origins of adaptive control are examined and some of the control policies developed during the 1950's are described. Consideration is given to the development of this technology in the flight-systems field which led to the MIT system and others using a model reference technique. Applications of these systems are discussed wherever possible. Some of the stability problems inherent in systems designed using these techniques are discussed and reference is made to the continued development of the steepest descent methods which appeared in the early 1960's. The problem of determining the stability boundaries essential in the application of the earlier methods of adaptive control was removed by the introduction of stability-based systems of Grayson, Rang, Butchart and Shackcloth, and Parks. These methods of synthesising the adaptive control laws by the use of Lyapunov's direct method and their shortcomings with regard to state measurement are considered. An adaptive hydraulic control system is described and the results of this experiment are given as examples of what can be achieved using relatively simple parametric controllers. Consideration is given to the synthesis of multi-variable adaptive control systems and the recent, more general, approach to these systems is examined. Some examples are included of the adaptation of time-varying process parameters and methods of improving the performance of stability-based systems are discussed.