Adaptive dynamic surface control for quadrotor-slung load transportation system with uncertainties

Quadrotors play a significant role in our lives and are transforming our lives. Transporting cable-suspended loads is an unavoidable quadrotor application trend and a hot research topic in the control field. Nonetheless, the load swing and unpredictability pose significant challenges to the quadrotor's stability. In this paper, an anti-swing controller with an inner-outer control strategy for the quadrotor-slung load transportation system is presented. To facilitate the controller design, the outer position dynamics are restructured in the form of cascades. Then, a virtual controller is created to force the underactuated states to the dynamic surface to ensure the position subsystem's stability. To improve robustness, an adaptive law is used to eliminate the effects of uncertain cable length. Lastly, a dynamic surface controller for the inner attitude subsystem is presented to drive the actual force to the virtual force. It is demonstrated that the control strategy can stabilize the quadrotor despite mass and cable length uncertainties.Comparative results are provided to demonstrate the efficacy and durability of the proposed method.