| || Real-time Parameter Estimation for Reconfigurable Control of Unstable Aircraft
Author : Kamali, C.;Pashilkar, A. A. ;Raol, J. R.
Source : Defence Science Journal ; Vol:57(4) ; 2007 ; pp 381-391
Subject : 629.7 Aeronautics
Keywords : Real-time parameter estimation;Adaptive/reconfigurable control;Equation error;Discrete Fourier transform;Recursive least squares;Digital filtering
Abstract : The real-time open-loop parameter estimation of unstable/augmented aircraft is essential for reconfigurable/adaptive control. This paper describes two parameter estimation algorithms based on the equation-error minimisation principle. One is the recently developed, well-established recursive discrete Fourier transform (DFT) technique in frequency domain. The other is an application of recursive least square (RLS) in equation2 error minimisation concept, applied to unstable/augmented aircraft parameter estimation. The RLS technique reported in this paper is implemented, for the first time, by a methodology that is analogous to the recursive DFT technique. Hence, in time domain, this can be viewed as a counter part of recursive DFT. The algorithms are implemented and tested for robustness against measurement noise. For the implementation, initially, data was generated under realistic conditions from simulation software that captures the dynamics of an unstable high performance aircraft, which is stabilised by full authority control laws. Subsequently, the algorithms are also tested with real flight data of a high performance unstable augmented fighter aircraft. The results bring out the merits of the algorithms and show their suitability for modelling of unstable aircraft, for subsequent adaptive/ reconfigurable control or fault diagnosis.