LINEAR MODEL EXTRACTION OF A LAUNCH VEHICLE BY SYSTEM IDENTIFICATION BASED ON SIX DEGREES OF FREEDOM SIMULATION

摘要

The transfer functions of the aerospace launch vehicle canrnbe extracted using well-known linearization methodology.rnThis paper presents an alternative to obtain the transferrnfunctions via closed-loop identification using six degreesrnof freedom nonlinear simulation software. The vehicle isrncharacterized by high nonlinearity, open loop instabilityrnand time-varying behaviours. The model structure withrnsome unknown parameters is obtained after mathematicalrnmodeling, thus the case of our problem is a parameterrnidentification one. Time-variant parameters are estimatedrnby Kalman filter approach with the aid of ARX modelrnstructure.