Dynamic high gain scaling: An application to robust adaptive output feedback for feedforward systems

P. Krishnamurthy, F. Khorrami

Research output: Chapter in Book/Report/Conference proceedingConference contribution


We propose an adaptive output feedback control design for global asymptotic stabilization of feedforward systems based on our recent results on dynamic highgain scaling based controller design for strict-feedback systems. The system is allowed to contain uncertain functions of all the states and the input as long as they satisfy certain bounds. Unknown parameters are allowed in the bounds assumed on uncertain functions. If the uncertain functions involve the input, then the output-dependent functions in the bounds need to be polynomially bounded. It is also shown that if the uncertain functions can be bounded by a function independent of the input, then the polynomial boundedness requirement can be relaxed. The designed controllers have a simple structure being essentially a linear feedback with state-dependent dynamic gains and do not involve any saturations or recursive computations. The observer utilized to estimate unmeasured states is similar to a Luenberger observer with dynamic observer gains. The Lyapunov functions are quadratic in state estimates, observer errors, and parameter estimation error. The stability analysis is based on our recent results on uniform solvability of coupled state-dependent Lyapunov equations. The controller provides strong robustness properties both with respect to uncertain parameters and additive disturbances. This robustness is the key to the output feedback controller design.

Original languageEnglish (US)
Title of host publication2004 5th Asian Control Conference
Number of pages9
StatePublished - 2004
Event2004 5th Asian Control Conference - Melbourne, Australia
Duration: Jul 20 2004Jul 23 2004

Publication series

Name2004 5th Asian Control Conference


Other2004 5th Asian Control Conference

ASJC Scopus subject areas

  • General Engineering


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