Universal integral controllers with anti-reset windup for minimum phase nonlinear systems

Deals with the design of robust integral control for single-input single-output (SISO) nonlinear systems with well defined normal form and exponentially stable zero dynamics. We develop further the universal controller design that was initiated in the work of Khalil (2000). The modification to the controller of Khalil is done in two steps. First, the integrator equation is modified to include not only the tracking error, but a linear combination of the tracking error and its derivatives, up to a certain order. Next, an additional input, in the spirit of classical anti-reset windup is added to the integrator to prevent it from winding up. Analytical results are given for both regional as well as,semiglobal regulation. The performance of the proposed controller is illustrated through simulations.