An adaptive regulator of the minimum-variance type in the presence of
disturbance uncertainty is considered in the paper. Supposing a linear
ARMAX model of the single input-single output system, a robustified d
irect adaptive control algorithm is derived using the robust statistic
al approach named M-estimation. The derived algorithm differs from the
conventional linear algorithms by the insertion of a suitably chosen
nonlinear transformation of the prediction error, which has to cut off
the large noise realizations named outliers. The global stability of
the proposed control system and self-optimizing property of the adapti
ve regulator is established theoretically using the martingale theory.
The feasibility of the approach is demonstrated with simulation.