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

Abstract

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.

Nonlinear observer-based impedance control of a fully-actuated hexarotor for accurate aerial physical interaction

“…In view of several shortcomings of underactuated UAVs in the task of aerial physical interaction, many researchers began to pay attention to the fully-actuated UAVs for interaction (Rashad et al , 2020; Allenspach et al , 2020). In our previous work, a nonlinear model predictive impedance control method is proposed for a fully-actuated hexarotor to perform the physical interaction with the environment through a rigidly attached tool (Jiao et al , 2023), and an observer-based geometric impedance control strategy is proposed for aerial physical sliding interaction allowing a 3D force with a constant norm applied to generic surfaces with unknown geometry (Jiao et al , 2021), however only flight simulations are conducted in these two works. In another our work, the physical interaction task with a certain force exerted outward is performed experimentally via a fully-actuated hexarotor, however the interacted force cannot be controlled accurately (Jiao et al , 2023).…”

Hybrid-disturbance-observer-based interaction control for a fully actuated UAV with tether-based positioning system

“…As for FUAVs, e.g. the one exploited within (Jiao et al , 2021; Rashad et al , 2020), its rotational and translational dynamics can be decoupled; as a consequence, it would be able to reject the tethered force and meanwhile maintain their attitudes for physical interactions. The existing control methods for TUAVs lack robustness to disturbances, which contain not only the force produced by taut tether but also model uncertainties and other external disturbances. Besides, measurement noise should also be considered.…”

“…As for FUAVs, e.g. the one exploited within (Jiao et al , 2021; Rashad et al , 2020), its rotational and translational dynamics can be decoupled; as a consequence, it would be able to reject the tethered force and meanwhile maintain their attitudes for physical interactions.…”

Nonlinear Model Predictive Impedance Control of a Fully Actuated Hexarotor for Physical Interaction

“…Therefore, a more suitable strategy is to design the controllers as inherently compatible with the environmental interactions. Among the existing interactive control methods, impedance and admittance control [18][19][20] are the most popular and widely used in various fields, particularly in robots interacting with humans/environments, which are more suitable for physical interactive control than the PID class method that is not model-based. The impedance method is exploited in [21] for a tethered UAV exerting physical human-robot interaction.…”