ON INTEGRAL BACKSTEPPING CONTROL: REGULATION TECHNIQUES AND TRANSIENT RESPONSE IMPROVEMENT

This paper investigates the issue of the tracking performance of integral backstepping control of a relative degree 2 system with nonlinear damping. The results of a previous study, which compares the tracking performance when the integrator is placed either at the first or second steps of the backstepping design are first reproduced. By saturating the integrator and considering the damping term as an uncertainty, a modification is made to the method where the integrator is placed in the first step and the performance of the three methods are compared with retuned feedback gains. A modified method of conditional integration is also proposed to improve the transient performance in terms of reduced overshoot in the tracking responses of both constant and time varying reference inputs. The results show that the modified method with the integrator placed at the first step of the recursive backstepping control design achieves tracking of constant and time varying waveforms in the presence of both matched and unmatched uncertainties with minimal overshoot.