Direct and indirect output feedback design for TORA system

This paper addresses the problem of stabilizing a TORA system without velocity measurement. For this purpose, two classes of output feedback designs, direct and indirect, are employed to design a nonlinear observer for estimating an unavailable variable (velocity variable). Moreover, the theory of cascaded time-varying systems has been used to improve the indirect output feedback controller and to enable the independent tuning of the observer and the controller. The results of Lyapunov stability analysis show globally asymptotic stability of the system in closed loop using the output feedback controllers designed in this paper.