Adaptive Take-Off Controller of a Land-Air Amphibious Vehicle on Unstructured Terrain

Due to the highly efficient multi-domain mobility, land-air amphibious vehicles are of great value in providing emergency assistance, such as disaster relief and reconnaissance. In this context, inconsistencies in the initial state and system uncertainties due to unstructured terrain in harsh environments pose a substantial obstacle to the take-off stability. Therefore, this article proposes a stability augmentation control scheme, which aims to achieve stable vertical take-off performance of the amphibious vehicle through accurate estimation of large initial state and effective compensation for uncertainties. Accordingly, an enhanced state predictor with a feedback regulator is designed to improve the accuracy of state estimation and the convergence rate of estimation error. Based on precise state estimation, the \mathcal {L}{1} adaptation law and the control law are applied for the online estimation and fast compensation of time-varying uncertainties during take-off transience. It is proved theoretically that the proposed stability augmentation control scheme guarantees the stability of the closed-loop system. Furthermore, comparative take-off experiments are conducted to demonstrate the effectiveness. The results show that the enhanced state predictor reduces the state estimation error by 80.31%. The stability augmentation controller realizes successful and stable take-off maneuver on uneven terrain with inclines of up to 20°, and improves the vertical take-off performance compared with other methods.