Root Locus Damping Ratio Constraints

The gray lines emanating from the origin of the continuous-time root locus represent damping ratio constraints. In the discrete-time case, the constraint appears as curved gray lines originating at (1,0) and meeting on the real axis.

Since the damping ratio constraints are a second-order approximation, percent overshoot constraints can be expressed in terms of damping ratios. See Percent Overshoot for more information.

See Design Constraints for more information and for an example of how to add these constraints to your root locus.