Observer-based Geometric Impedance Control of a Fully-Actuated Hexarotor for Physical Sliding Interaction with Unknown Generic Surfaces

Aerial physical interaction is a promising field for unmanned aerial vehicles in future applications. This paper presents a novel paradigm for automatic aerial contact-based sliding interaction (inspection/cleaning) tasks in aerial robotics allowing a 3D force with a constant norm to be applied on generic surfaces with unknown geometry. The interaction task is achieved by a fully-actuated hexarotor equipped with a rigidly attached end-effector under a passivity-based geometric impedance controller and a new sliding-mode extended state observer to estimate the interaction wrench. In order to increase the observer performance and reduce the estimation chattering phenomenon, the observer is innovatively incorporated with a super-twisting algorithm and a sigmoid function with a switching gain being adaptively updated by a fuzzy logic system. A detailed stability analysis for the observer is presented based on the Lyapunov stability theory. The proposed control approach is validated in several simulations in which we try to accomplish the aerial physical sliding interaction task with different types of objects under various sliding speeds.