Automated Ziegler Nicholas PID Tuning

The submitted code is aimed to provide an easy tool to find the gain parameters of P,PI and PID using Ziegler Nicholas by providing the numerator and denominator coefficients of the plant mathematical model in Laplace domain. It determines the Critical Gain Kc and Ultimate Period Pu from Nyquist plot and hence calculating gain values for P, PI and PID. Thereafter plotting the closed loop responses of P,PI and PID calculated values. The period of plotting is also adjustable.
This GUI is part of a course conducted at Mechatronics Dept., Misr University for Science and Technology.

Here is a video demonstrating the operation:
http://youtu.be/ei-sQ_ugB1s?list=UUyoWzcKHpRCNYID2-nhwJXw