AN EKF BASED PROCEDURE FOR AUTOMATIC PATH FOLLOWING IN TURBULENT AIR

Abstract

Aim of the present paper is to propose a procedure to afford an accurate automatic path following in turbulent air. The technique is based on the simultaneous employment of two different EKF. The first estimates disturbances, the second one estimates deflection that are necessary to reject the estimated disturbances. The first EKF uses measurements gathered in turbulent air. The second EKF obtains command laws able to follow the desired flight path rejecting disturbances. To purchase the objective, aerodynamic coefficients have been modified by adding entirely new derivatives or synthetic increments to basic ones. The modified aircraft parameters are determined by augmenting the aircraft’s state. The filter determines the “new” set of derivatives that contains functions of control displacements. The desired flight path is injected into the second EKF as artificial instrumental measurements and the filter is tuned up to follow these. The obtained control laws are adaptive since they depend by either the characteristics of the disturbance or the desired flight path. Proposed procedure requires low computational power, therefore it is particularly suited for UAS. Besides it’s simple to implement on board, so it may be successfully employed on low cost platforms.