A NONLINEAR OBSERVER FOR ESTIMATING PARAMETERS IN DYNAMIC-SYSTEMS

A new algorithm for estimating constant parameters in a dynamic system is presented. A generalization of a recently developed method for est imating the coefficient of friction in a dynamic system; the algorithm is a reduced-order observer having two nonlinear functions, one being the Jacobian of the other. If the dynamics of the system are affine i n the parameters to be estimated, the error in estimation of these par ameters satisfies a linear, time-varying homogeneous differential equa tion. By proper choice of the nonlinear function in the observer, it i s possible to achieve asymptotic stability of the estimation error. Al though the algorithm is derived on the assumption that the process sta te can be measured, it can be used to estimate the parameters concurre ntly with the state. Example applications, including one of adaptive c ontrol, are presented. (C) 1997 Elsevier Science Ltd.