Coordinated Control of Underwater Biomimetic Vehicle–Manipulator System for Free Floating Autonomous Manipulation

This article presents a coordinated vehicle-manipulator control method for an underwater biomimetic vehicle-manipulator system (UBVMS) to implement floating autonomous manipulation in practice. An algorithm framework composed of adaptive tracking differentiator (ATD), extended state observer (ESO), improved nonsingular terminal sliding-mode control (I-NTSMC), fuzzy-logic controller (FLC), and estimator of manipulator disturbances, is proposed. The ATD is designed to generate desired motion state and alleviate noise. The ESO is developed to estimate the motion state, systematic uncertainties, and external disturbances. The proposed I-NTSMC method assures the finite-time convergence of the system states and alleviate chattering. The estimation of the manipulator disturbances is incorporated into the control strategy to enhance the station keeping of the vehicle. Finally, underwater autonomous free floating manipulation experiments about opening a door and grasping objects are conducted to validate the theoretical results and confirm the feasibility of the proposed control strategy.