Uniform Second-Order Sliding Mode Observer for mechanical systems

In this paper we introduce a modification to the classical Second-Order Sliding Mode Observer (SOSMO), used mainly for mechanical systems, and that consists in adding higher order nonlinear injection terms. Besides the usual finite-time con- vergence and exactness of the SOSMO, this new algorithm makes the convergence uniform with respect to the initial conditions, that is, the observation error reaches exactly and robustly the origin in a convergence time that is uniformly bounded above for every initial condition. The properties of the Uniform SOSMO (USOSMO) are studied using strong Lyapunov functions.