The problem of observer design for Lipschitz nonlinear systems is considered. A new dynamic framework which is a generalization of previously used Lipschitz observers is introduced and the generalized sufficient condition that ensures asymptotic convergence of the state estimates is presented. The equivalence between this condition and an H/sub /spl infin// optimal control problem which satisfies the standard regularity assumptions in H/sub /spl infin// optimization theory is shown and a parameterization of all possible observers is also presented. A design procedure which is less restrictive than the existing design approaches is proposed, and a simulation example is given to illustrate the observer design.

In this article, the design and control of a new coaxial tilt-rotor unmanned aerial vehicle (CTRUAV) are presented. The CTRUAV is an electric-powered unmanned aerial vehicle with a special configuration, which is composed of two pairs of tiltable coaxial rotors and a rear rotor. A CTRUAV prototype has been designed by 3-D computer-aided design software and constructed according to the designing scheme. The dynamic model of a CTRUAV is derived by utilizing the Euler–Lagrange equation, which considers the special features of the coaxial rotors and air drag forces on the CTRUAV. An adaptive controller is developed to realize motion control for the CTRUAV. The adaptive controller includes two subcontrollers: an inner-loop attitude controller and an outer-loop velocity controller. The stability of the resulting closed-loop CTRUAV system is analyzed via the Lyapunov method. Finally, several simulations and real experimental tests are implemented to validate the effectiveness of the developed CTRUAV system.