RISE-Based Trajectory Tracking Control of an Aerial Manipulator Under Uncertainty

This letter presents a robust integral of the sign of the error (RISE)-based controller for an aerial manipulator consisting of a multi-rotor and a robotic arm which guarantees tracking error convergence to zero in the presence of uncertainties. To rigorously address underactuatedness issue, the system dynamics is decomposed into the two subsystems for which a robust controller is derived. As an intermediate result, if there exists no uncertainty, we show that the nominal closed-loop system with the proposed nominal controller is asymptotically stable without assuming that the attitude error term in the underactuated part is zero by cascaded system analysis tool. Then, a robust controller combining a nominal controller and a RISE controller is proposed and applied to both subsystems. Tracking error convergence is strictly proved through Lyapunov-based stability analysis. The performance of the controller is demonstrated in simulation with comparative studies where the proposed controller outperforms the other compared controllers in error convergence.