Global Output Feedback Tracking Control of Euler-Lagrange Systems

We solve the problem of global output feedback tracking control of general Euler-Lagrange systems without velocity measurement. The output feedback scheme consists of a novel nonlinear observer and any certainty equivalence tracking controller satisfying certain assumptions. Using theory for cascaded systems we guarantee uniform stability and convergence of the certainty equivalence output feedback scheme. Simulation results are included to illustrate the performance of the popular Slotine and Li controller together with our proposed observer.