  The notion of the relaxed Robust Control Lyapunov Function (relaxed RCLF) is
introduced and is exploited for the design of robust feedback stabilizers for
nonlinear systems. Particularly, it is shown for systems with input constraints
that relaxed RCLFs can be easily obtained, while RCLFs are not available.
Moreover, it is shown that the use of relaxed RCLFs usually results to
different feedback designs from the ones obtained by the use of the standard
RCLF methodology. Using the relaxed RCLFs feedback design methodology, a simple
controller that guarantees robust global stabilization of a perturbed chemostat
model is provided.
