A COMPARATIVE-STUDY OF NORMALIZED AND UNNORMALIZED TUNING ERRORS IN PARAMETER ADAPTIVE-CONTROL

In the past year several advances in the development of adaptive control for non-linear systems have made it clear that algorithms not using error normalization have several significant advantages over algorithms which do, in spite of their much greater complexity. In this paper simple examples are used to give a detailed account of the essential differences in structure between adaptive algorithms of the normalized and unnormalized types. It is explained why only the latter readily generalize to non-linear process models with non-global Lipschitz non-linearities. It is shown that one of these algorithms is capable of stabilizing linear process models with different relative degrees.