Globally stable nonlinear control of HIV-1 systems

This paper addresses the problem of controlling the predator-prey like model of the interaction among CD4/sup +/ T-cell, CD8/sup +/ T-cell and HIV-1 by an external drug agency. By exploring the dynamic properties of the system, the original system is first regrouped into two subsystems, then a nonlinear global controller is presented by designing two controllers over two complimentary zones: a local controller on a finite region and a global boundary controller over its compliment. The local controller is developed to guarantee the nonnegative properties and avoid control singularity problem within the neighborhood of origin /spl Omega/. The complimentary controller is designed via backstepping for both the subsystems respectively over the complimentary region. The closed-loop system is globally stable at nominal values, the resulting controller is singularity free and guarantees the nonnegative properties. Simulation results are demonstrated to show the effectiveness of the proposed methods.