On‐line system identification for aircraft with distributed control effectors

Abstract

An algorithm is presented for the identification of aircraft stability derivatives and distributed control derivatives, in real time. Feedback control correlates the effectors' displacement with the aerodynamic angles, while the most commonly used control allocation algorithms correlate the effectors. The result is that valid derivative estimation is not possible. This paper addresses the effector identification problem by including decorrelating excitation into the control allocation cost function while still satisfying the desired control moment, and therefore does not introduce any residual perturbations into the motion variables. A two-step identification algorithm is used where the stability derivative and a generalized control derivative are identified in the first step. Results are shown for a stability axis roll maneuver with the stability and control derivatives being identified for five differential lateral directional effectors. Published in 1999 by John Wiley & Sons, Ltd. This article is a US Government work and is in the public domain in the United States.