Output feedback globally stable tracking of nonstationary Euler-Lagrange systems with large unknown disturbances

This paper provides a solution to the problem of global (asymptotical) stabilization of programmed motion of a system described by nonstationary Euler-Lagrange equations perturbed by external forces. These perturbations may be nondissipative and even unobservable; only their time- and space-varying bounds of general form should be known. The control law uses only values of generalized coordinates of the system but not their derivatives. For control design, the new technique named “dynamical decomposition” is proposed. This design methodology can be useful for other stabilization and tracking problems where the passivity technique is unapplicable