A Nonlinear Disturbance Observer-based Adaptive Controller Considering CG Variation of Urban Aerial Mobility

Abstract

This paper aims to propose a nonlinear adaptive attitude control method for urban aerial mobility (UAM) to counteract its center of gravity (CG) variations, which is considered one of the challenging issues for UAM development. To this end, we firstly analyze the effect of the dynamic change caused by the CG variations rigorously. The analysis result uncovers that the model uncertainties (it can be regarded as the internal disturbances) due to the CG variations are not rapidly changing during the operation of UAM. Based on this observation, a nonlinear adaptive controller is suggested to attenuate the disturbances by leveraging on a two-stage design procedure with the concept of the disturbance observer-based control (DOBC) and the three-loop control topology in this paper. To be more specific, the baseline controller, based on the feedback linearization control (FBLC) in conjunction with the three-loop control structure, is designed by including the disturbances as exogenous inputs to the system. And then, the nonlinear disturbance observer is separately designed to estimate these disturbances. Finally, the performance of the proposed method is examined through numerical simulations.