On a modification approach to a class of Lyapunov-based robust controllers subject to input constraint

This paper presents an approach to the modification of a class of Lyapunov-based robust controllers when the input constraint needs to be taken into account. The approach shows advantages in enhancing the input utilization and in retaining the stability and the robustness of the original control. The modification comprises two stages. The first stage is to reshape the original control for satisfying the constraint and preserving the original control direction. The second stage is to apply a structure for enhancing the input utilization and retaining the stability and robustness developed in the first stage. In addition, an estimate of the stabilization region is employed to select the design parameters for the local, semiglobal, and global stabilization.