Discussion on: "Combined Adaptive Controller for UAV Guidance"

Combined algorithms that include both variable structure system and identification approaches are proposed in this paper for guidance of UAV. The approach is based on the application of the so called ‘‘shunt’’ – parallel feedforward compensator. A similar approach based on the feedforward compensator for stabilization of plants of any relative degree was proposed by Bartolini et al. [1]. It is recommended that this paper [1] be refered when considering the contribution of the paper under discussion. Application of the ‘‘Feedback Kalman–Yakubovich Lemma’’ [9] for design of the adaptive controller based on the parallel feedforward compensator is the contribution of the paper under discussion with respect to [1]. The contribution of the paper under discussion with respect to [4] is marginal. As can be seen from Figs 7 and 8 the adjustable parameters converge to their true values. The convergence of the parameters to their true values is achieved under the condition of the persistency of excitation. A mathematical proof that the regressor is persistently exciting could be a subject of further research.