No abstract

With the increasing demand for interactive aerial operations, the application of aerial manipulators is becoming more promising. However, there are a few critical problems on how to improve the energetic efficiency and pose control of the aerial manipulator for practical application. In this paper, a novel cable-driven aerial manipulator used for remote water sampling is proposed and then its rigid-flexible coupling dynamics model is constructed which takes joint flexibility into account. To achieve high precision joint position tracking under lumped disturbances, a newly controller, which consists of three parts: linear extended state observer, adaptive super-twisting strategy, and fractional-order nonsingular terminal sliding mode control, is proposed. The linear extended state observer is adopted to approximate unmeasured states and unknown lumped disturbances and achieve model-free control structure. The adaptive super-twisting strategy and fractional-order nonsingular terminal sliding mode control are combined together to achieve good control performance and counteract chattering problem. The Lyapunov method is utilized to prove the overall stability and convergence of the system. Lastly, various visualization simulations and ground experiments are conducted, verifying the effectiveness of our strategy, and all outcomes demonstrate its superiorities over the existing control strategies. KEYWORDSAerial manipulator; cable-driven; adaptive super-twisting; linear extend state observer; fractional-order nonsingular terminal sliding mode Nomenclature M Inertia matrix C Coriolis and centrifugal matrix G Gravitational force vector J Inertia matrix of motors D Damping matrix of motors K s Joint stiffness matrix K d Joint damping matrix q Angular position vector of links θ Angular position vector of motors