Logarithmic root loci for continuous-time loops

We propose that the logarithms of closed-loop poles be drawn instead of the plain poles in root loci for continuous-time linear loops, to help visualize significant closed-loop frequency responses simultaneously at specific values of the changing open-loop parameters. We also promote the splitting of the loci into pairs of graphs showing the imaginary and real parts of the logarithms of the poles as separate functions of the changing parameters, since this allows one to foresee the effects of parameter changes on the frequency responses and, therefore, to build computational environments in which the user may steer the design of feedback control systems.<>