Modified Equation Error Methods for Parameter Estimation

Abstract

Two parameter estimation algori tt.ms are described for detern1ining the stability and control derivatives of an aircraft and an automobile from the measured input and output time histories, The algorithms are based on the equation error method.The first method called MEEM - acronym for Modified Equation Error Method - is a simple, fast and reasonably accurate one step method. In the second method SPECO - acronym for System Parameter Estimation through Constrained Optimization - the cumulative equation error is minimized by a constrained optimization technique. The inforrnation regerding the polarity of certain parameters on the basis of physical consideration is used as constraints in the technique, Good results are obtained when applied to the extractior. of stability and control derivatives of an aircraft and an automobile even from arbitrary zero starting values for the iteration. Eut the program is slow like all other direct search rr,ethods and hence perhaps only useful for off-line parameter estimation.