Robust Control of a Duocopter by Discrete-Time Sliding Mode Techniques and an Extended Kalman Filter for Disturbance Compensation

This paper proposes a discrete-time cascade control for a Duocopter which represents a two-rotor helicopter com-bined with a guiding mechanism: A nonlinear MIMO sliding mode control loop is responsible for the positioning of the Duocopter, while its rotation angle is controlled in a linear inner control loop. Feedforward control counteracts the nominal coupling forces related to the guidance. Moreover, an extended Kalman filter (EKF) estimates selected states and remaining errors concerning the nominal coupling forces. The sum of the feedforward part and the estimates can be used to robustly and accurately compensate for the impact of the guiding mechanism on the motion of the Duocopter. Thereby, an excellent tracking performance is achieved.