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Vol: 60(74) No: 1 / March 2015      

Simultaneous Aircraft Nonlinear Model and Inertial Parameter Identification Based on Real Flight Data
Loránd Lukács
Department of Control engineering and Information Technology, Budapest University of Technology and Economics, Magyar Tudósok krt.2, H-1117 Budapest, Hungary, e-mail: lukacsl@iit.bme.hu
Béla Lantos
Department of Control engineering and Information Technology, Budapest University of Technology and Economics, Magyar Tudósok krt.2, H-1117 Budapest, Hungary, e-mail: lantos@iit.bme.hu


Keywords: aircraft nonlinear dynamic model, aircraft identification, inertial parameter identification, center of gravity, inertia matrix identification.

Abstract
The scope of the paper is the identification of an aircraft’s nonlinear dynamic model together with its inertial parameters. The platform for identification is a sailplane with the presented method using real flight data. It is assumed that the aircraft has neither an inbuilt navigational system, nor any sensors for recording input signals. Therefore, the aircraft states are estimated using externally mounted GPS, IMU and magnetometer readings and a multi-mode, multilevel state estimator based on EKF. The input signals consisting of aileron, elevator and rudder surface deflections are determined through image processing. The state estimation and input signal determination is detailed in previous papers while the current paper concentrates on the identification of the center of gravity and inertia matrix, together with the force-torque model. The force-torque model is based on the rigid body dynamic equations containing additional weighted nonlinear terms for the 3D forces and torques. The dominating nonlinear functions are selected according to physical considerations with their parameters determined using an SVD technique. The disturbance caused by wind effects are also taken into consideration. The inertial parameters are determined using global search based optimization on an appropriately selected objective function.

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