Nonlinear output stabilization of uncertain systems

An alternative stabilization scheme is offered whereby the output of the system is fed back. This method is contrasted with a full-state feedback strategy using observed states. The design is illustrated utilizing a single-flexible-link manipulator where compliance of the link and other nonidealities are treated as a lumped nonlinearity/uncertainty. The regulation method guarantees not only that the closed-loop system is globally uniformly asymptotically stable but also that the norm of the states of the system decays at least as fast as a known exponential. The method may be easily extended to the problem of output tracking by the addition of a full-state observer which guarantees estimates that converge exponentially to the actual states.