Attitude Tracking of the Small-Scale Helicopter System using Disturbance Observer based Sliding Mode Control

Robust Internal-Loop Compensator Based Sliding Mode Control of Nonlinear Systems in the Presence of Mismatched Disturbances

“…The DOB based SMC [39], [40], as well as the RIC based SMC using decentralized [37] and centralized [38] approach have been applied to the helicopter CE 150 and reported the most promising tracking performance and robustness properties, in comparison with other control methods referenced therein. Here, the control performance of three control methods are compared through both simulation studies and experimental tests of the helicopter CE 150: the proposed integral SMRIC (I-SMRIC) with the phase-lead compensator (75), the RIC based I-SMC with the first-order low pass Q-filter [38] and the NDOB based I-SMC [15].…”

“…Remark 7: The estimation (40) does not require the lumped disturbance τ dis to have constant steady-state values, or even to be continuous, but only to be bounded. Thus, the SMRIC approach has significantly relaxed constraints imposed on the mismatched uncertainties in comparison with the NDOB based SMC [15] and extended DOB based SMC [29].…”

“…This subsection presents a summary model of the helicopter CE 150, since the detailed dynamic model is already described in [37], [39], [40]. Fig.…”

“…Therefore, a) Unlike the NDOB based SMC [15], it does not require constant steady-state values of the mismatched uncertainties for stabilization of the DOB (for example, wind gusts in flight control systems are bounded disturbances that do not have constant steady-state values), and b) Unlike the extended DOB based SMC [29], it does not require mismatched disturbances to be continuous (for example, wind gusts in motion control systems are bounded disturbances that do not have to be continuous), 6) It exhibits significant tracking performance of the application example in comparison with the NDOB based SMC [15], as well as improved robustness to the modeling uncertainties, parameter variations, external disturbances and mismatched uncertainties, even in the scenario with the same values of the switching control term. Furthermore, the following extensions of our previous work [37]- [40] are presented:…”

“…1) The proposed SMRIC method aims to solve the disturbance compensation problem for nonlinear MIMO systems with arbitrary DRDs (matched and mismatched disturbances), 2) The generalized sliding surface (not particular one, as in [37]- [40]) is utilized in the SMRIC framework, 3) Stronger results in stability analysis are proved, ensuring the finite-time convergence of the system trajectories to the generalized sliding manifold, as well as the asymptotic stability of the equilibrium, and 4) The RIC based phase-lead compensator is utilized, through the SMRIC framework, for attenuation of additional disturbances in the application example, thus increasing the stability margins and decreasing settling times of the closed loop system. The paper is structured as follows.…”