A design method of universal adaptive servo controller

A design method of universal adaptive servo controllers for processes with unknown degrees and unknown signs of high-frequency gains, and with uncertain relative degrees r, r+1 or r+2 (with known r/spl isin/N), is presented. This is an extension of Morse's universal stabilizers where it was assumed that the relative degrees are uncertain but known to be 1 or 2. It is shown that the proposed servo controllers can deal with such uncertainties, and estimate unknown internal models of disturbances and reference signals. The asymptotic stability of error systems is proved without any assumption on sufficient excitation of signals.