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In this paper, the problem of driving angular position of a direct current servomotor system with unmodeled wide backlash nonlinearity is addressed. In order to tackle this problem, a control scheme based on an adaptive super twisting algorithm is proposed. In order to implement the proposed controller, information about angular velocity is estimated by means of a robust differentiator. Based on a simplified model of the system, the proposed scheme increases robustness against unmodeled dynamics as backlash, as not all the parameters of the system nor the bounds of the perturbations are required to be known. Experimental results considering a wide backlash angle near to 2π, illustrate the feasibility and performance of the proposed control methodology.Key words: Robust control, Adaptive control, Servomotor, Backlash nonlinearity Robusno adaptivno upravljanje istosmjernim servomotorom s nelinearnom širokom zračnosti. U ovom radu bavi se problemom kutnog pozicioniranja istosmjernog sevomotora s nemodeliranom nelinearnošću široke zračnosti. Za rješenje tog problema predlaže se korištenje upravljačke sheme bazirane na algoritmu adaptivnog uvijanja. Kako bi se implementiralo predloženo upravljanje, kutna brzina estimira se korištenjem robusnog diferencijatora. Bazirana na pojednostavljenom modelu sustava, predložena shema povećava robustnost u odnosu na nemodeliranu dinamiku kao što je zračnost. Pritom nije potrebno poznavanje svih parametara sustava niti očeki-vane granice smetnji. Eksperimetalni rezultati, koji uzimaju u obzir široki kut zračnosti od skoro 2π, ilustriraju izvodljivost i učinkovitost predloženog algoritma upravljanja.

In this paper, the design of attitude and airspeed controls for a fixed-wing unmanned aerial vehicle by means of an Adaptive Super Twisting Algorithm approach is addressed. In order to implement these controllers and taking into account the difficulties for measuring some of its states, necessary information about inertial attitude and airspeed is estimated using Super-Twisting Observers. This control scheme increases robustness since it is not necessary to know the bound of the perturbations affecting the system or the exact values from the parameters of the system. Furthermore, due to the finite-time converge of the observer, the stability of the closed-loop system is guaranteed. Simulation results illustrate the performance of the proposed scheme under unmodelled dynamics, noisy measurements and external disturbances.