An Adaptive Scheme to Estimate Unknown Parameters of an Unmanned Aerial Vehicle

This paper deals with tracking control problem for six degrees of freedom (6-DOF) nonlinear quadrotor unmanned aerial vehicle (UAV). A virtual control design using PD controller is proposed for tracking control position. The rotational dynamics of UAV is considered to have several unknown parameters such as propeller inertia, rotational drag coefficient and an external disturbance parameter. To handle this issue, an adaptive scheme using the certainty equivalence principle is developed. The basic idea behind this scheme is to cancel the nonlinear term by applying a similar nonlinear structure in the feedback control design. The unknown parameters are replaced by estimated parameters generated by adaptation law. The rigorous theoretical design and simulation results are presented to demonstrate the effectiveness of the controller.