The application of modified output error method on alflex flight data

Abstract

A modified output error method is an algorithm to estimate the aerodynamic characteristics and control inputs of a flight vehicle. The algorithm is successfully applied on YF16 aircraft flight data, the results of which have been reported at the ISIP 2000. Earlier, the velocity, three Euler angles, and the altitude could be estimated fairly well; however, there were rather large errors that appeared in the estimation of the aerodynamic force and moment coefficients. The best selection of the sampling intervals, the lead time, and some improvements of the algorithm led to the estimation of these aerodynamic coefficients fairly well, and many tactical maneuvers of YF16 aircraft flight data were analyzed and shown. This chapter verifies the performance in more detail, particularly for the estimation of high frequency variables. The applied data are the flight experiment data of the ALFLEX (Automatic Landing Flight Experiment) supplied by NAL (National Aerospace Laboratory)/NASDA(National Space Development Agency of Japan), which include the effect of high frequency intentional control surfaces' vibration inputs. Following this, the chapter explains the flight experiments of the ALFLEX. Thereafter, the mathematical model of the ALFLEX with its equations of motion and the relation between observed data and variables are illustrated. Furthermore, the algorithm of the modified output error method is briefly explained. Finally, the results are discussed.