CONTINUOUS VARIABLE-STRUCTURE CONTROLLER FOR BLDDSM POSITION CONTROL WITH PRESCRIBED TRACKING PERFORMANCE

The continuous, accurate, and robust sliding mode tracking controller based on a disturbance observer for a brushless direct drive servo mot or (BLDDSM) is presented. Although the conventional sliding mode contr ol (SMC) or variable structure control (VSC) can give the desired trac king performance, there exists an inevitable chattering problem in con trol which is undesirable for a direct drive system. With the proposed algorithm, not only are the chattering problems removed, but also the prescribed tracking performance can be obtained by using the efficien t compensation of the disturbance observer. The design of the sliding mode tracking controller for the prescribed, accurate, and robust trac king performance without the chattering problem is given based on the results of the detailed stability analysis. The usefulness of the prop osed algorithm is demonstrated through the computer simulation for a B LDDSM under load variations.