Observer-based adaptive control for slung payload stabilization with a fully-actuated multirotor UAV.

This article presents an observer-based adaptive sliding mode controller for a fully-actuated hexacopter unmanned aerial vehicle, designed for trajectory tracking in a perturbed environment while carrying a cable-suspended payload. Based on the unavailability of a payload swing sensor, an extended high-gain observer is designed to provide full-state and disturbance estimation including payload motion. Such disturbances are compensated into the control loop to dampen the oscillations, thus improving the flight performance of the hexacopter driven by the adaptive control, providing robustness against bounded perturbations and chattering reduction. The stability analysis of the observer-based controller is guaranteed through Lyapunov theory. Simulations using a multibody emulator demonstrate time reduction in payload dampening while controlling the aircraft trajectory, compared to a feedback regulation-based adaptive controller.

Novel adaptive law for super-twisting controller: USV tracking control under disturbances.

A novel adaptive super-twisting control algorithm, for Unmanned Surface Vehicles (USV) tracking control is presented. The proposed adaptive law is obtained using a Lyapunov approach, to analyze the system closed-loop stability. Furthermore, several conditions are given to guarantee robustness in presence of unknown bounded disturbances/uncertainties, chattering mitigation and the finite-time convergence. This adaptive control strategy has the advantage that the controller gains, which are in terms of a single control parameter, requires adjusting a small number of parameters compared with other adaptive strategies, moreover and its dynamics is smooth, improving the controller performance. To assess the proposed control methodology effectiveness, a trajectory tracking control is designed and implemented on an unmanned surface vehicle under the action of bounded unknown uncertainties and external perturbations. Numerical simulations and experimental results conducted with a vessel prototype demonstrate the performance and advantages under payload variations and external environmental conditions. Finally, a comparative study between the proposed approach with other adaptive super-twisting works has been conducted.

Extended observer based on adaptive second order sliding mode control for a fixed wing UAV.

This paper addresses the design of attitude and airspeed controllers for a fixed wing unmanned aerial vehicle. An adaptive second order sliding mode control is proposed for improving performance under different operating conditions and is robust in presence of external disturbances. Moreover, this control does not require the knowledge of disturbance bounds and avoids overestimation of the control gains. Furthermore, in order to implement this controller, an extended observer is designed to estimate unmeasurable states as well as external disturbances. Additionally, sufficient conditions are given to guarantee the closed-loop stability of the observer based control. Finally, using a full 6 degree of freedom model, simulation results are obtained where the performance of the proposed method is compared against active disturbance rejection based on sliding mode control.