Semiglobal H∞ Control for a Class of Nonlinear Systems via Dynamic Output Feedback

The problem of disturbance attenuation is addressed for a class of nonlinear systems with disturbance having bounded L
2
norm. By connecting semiglobal H
∞
control with the semiglobal solution of the dissipation inequality, a design procedure for output feedback control laws is presented on the basis of high-gain observer. For any given bounded subset of L
2
[0,∞] and any given compact subset of state space, the resulting controllers render the L
2
gain between disturbance in the given bounded subset and the output less than the prescribed number, and achieve locally asymptotically stable with the domain of attraction containing the compact subset without disturbance.