Adaptive Generalized Dynamic Inversion Based Trajectory Tracking Control of Autonomous Underwater Vehicle

Abstract

This paper presents the two-loops structured control system based on Adaptive Generalized Dynamic Inversion (AGDI) for the position and attitude control of Autonomous Underwater Vehicle (AUV). The outer-loop is responsible to provide the pitch and yaw tilting commands to the inner-loop, which in turns generates the tilting angles that are required to control its position in depth and east directions respectively. In AGDI control, the particular part is formulated by prescribing the constraint differential equations based on the deviation functions of the position coordinates and attitude angles. The control law is realized by inverting the constraint dynamics using Moore-Penrose Generalized Inverse (MPGI). The involved null control vector in the auxiliary part of AGDI is constructed to guarantee global closed loop stability of the linear and angular velocities. The singularity problem is addressed by incorporating a dynamic scaling factor in the expression of MPGI. The integration of an additional term based on Sliding Mode Control with adaptive modulation gain provides robustness against system nonlinearities, uncertainties and tracking performance deterioration due to dynamic scaling, such that semi-global practically stable position and attitude tracking is guaranteed. To demonstrate the tracking performance of the AGDI control, numerical simulations are conducted on six degrees of freedom simulator of the Monterey Bay Aquarium Research Institute (MBARI) AUV, under nominal and perturbed marine conditions.