A Nonlinear Model Predictive Control Strategy for Water Sampling Using a UAV with a Slung Mechanism

In this work, a nonlinear Model Predictive Control (NMPC) strategy is presented for stabilizing an Unmanned Aerial Vehicle (UAV) with a cable-suspended liquid collection device during water sampling from aquatic environments. Building upon our previous work, an NMPC scheme is developed which incorporates the disturbances acting on the multirotor and attains the accurate hovering of the vehicle while simultaneously state and input constraints are satisfied. Once the UAV is stabilized above the water surface, a custom electromechanical mechanism is activated to collect water samples. The performance of the proposed controller and the reliability of the sampling device are demonstrated through real-world experiments in a river with high water flow.