Dynamic surface output regulation method for a class of uncertain nonlinear systems

For a class of nonlinear uncertain systems driven by a linear, neutrally stable exosystem, output regulation problem is considered with the existence of unmodeled dynamics and external disturbances. The dynamic surface method and internal model principle were utilized to propose a control design method. Based on necessary condition of output regulation problem for nonlinear systems, the output regulation problem was transformed to a stabilization problem by using state variable change and a canonical internal model. The dynamic surface method first introduced order filter into the backstepping design to cope with the problem of "explosion of the terms" in it. An internal equation with error was designed via exosystem information, and a robust control law was designed to stabilize the closed-loop system. Simulation results via exosystem information show that the control scheme ensures all signals to be bounded and the error signal to be within a desired range.