Reduced observer for mechanical systems

The problem of nonlinear reduced order observer design for mechanical systems is considered. It is assumed that a system is represented in a linear form with respect to unobserved components of the phase vector. The method is based on a synthesis of invariant relations for the extended system of differential equations. This relations are considered as additional algebraic equations for unknown components of the state. As an application of this method the problem of determination of the angular velocity vector of rotating rigid body under measuring of its projection on one of the connected with the body axes is studied.