robust mrac for a wing rock phenomenon in delta wing aircrafts

Wing rock phenomenon is undesired vibration in rolling angle occurring in delta wing aircraft at large angles of attack. this paper presents three versions of model refernce adaptive controllers; namely classical mrac, σ-modified mrac and weighted σ-modified mrac to control the rolling dynamics under wing rock phenomenon with the presence of unmatched disturbance. the stability analysis of new proposed strategy for weighted σ-modified mrac has been presented. the effectiveness of the controllers is assessed in terms of their robusness under unmatched disturbance. the simulated results based on matlab/simulink show that σ-modified adaptive controller gives better robustness characteristics than classical one; as it could confine different aircraft responses within smaller bounded limits. moreover, as compared to σ-modified controller, weighted σ-modified controller gives better enhancement in terms of robustness, control effort and error charcteristics.