An Improved Backstepping Controller with an LESO and TDs for Robust Underwater 3D Trajectory Tracking of a Turtle-Inspired Amphibious Spherical Robot

In this paper, a double closed-loop backstepping controller is designed for 3D trajectory tracking of turtle-inspired amphibious spherical robot suffering from problems that include model uncertainties, environmental disturbances, and unmeasured velocity. The proposed scheme tackles three primary challenges: the differentiation explosion traditional method, velocity, consideration lumped disturbances. Beginning with an outer-loop controller, virtual feedback variable constructed to simplify design controller. Meanwhile, avoid problem explosion, differentiators (TDs) are utilized estimate desired velocity in inner-loop Moreover, there some uncertainty disturbances task (TASR), such as parameters hydrodynamic A linear extended state observer (LESO) compensate Furthermore, states TASR unmeasured, LESO also surge, yaw, heave degrees. Therefore, only needs supply its position orientation information task. Note paper details both process rigorous theoretical analysis. addition, numerical simulations conducted, results demonstrate feasibility superiority method.