A New Frequency Response Plot of Linear SISO Systems

The projection of the Nyquist diagram of a SISO linear system onto the Riemann sphere is recently used to represent the frequency responses. However, it is difficult to display the Riemann plot clearly in a plane since the Riemann sphere is a three dimensional object. To address this problem, the map projection of Riemann plot is introduced to obtain a two dimensional plot. The new frequency response plot plays the same role in modern robust control as Riemann plot, and easy to draw in a plane