Adaptive stabilisation of extended nonlinear output feedback systems

The paper deals with the adaptive stabilisation for a class of uncertain nonlinear systems whose nonlinear terms are functions of two state variables. The uncertainty is parametrised by an unknown constant parameter vector affined to smooth nonlinear functions. The model format considered in the paper can be viewed as an extension to the standard output feedback systems with nonlinear terms of the single output which has been extensively studied recently. Based on the principle of adaptive backstepping design, an adaptive control algorithm is proposed to stabilise the system in a feasibility region, using the feedback of the system output which is a vector containing the two state variables.