a5 and b4 Consider the following block diagram of a PID con

a=5 and b=4 ;

Consider the following block diagram of a PID control system. Determine the optimal PID parameters using the Ziegler-Nichols process reaction method (by using MATLAB/Simulink). Obtain an open-loop unit-step response of your plant first. Give the resulting s-shaped unit-step response curve and your calculations on this curve. Find the optimal sets of controller parameters for P, PI, and PID. Give unit-step responses for these three cases of your closed-loop tuned system. Comment on the performance of your control system.

Solution

transfer function = (kp + s*kd + kd/s)*(s(s+a)(s+b))

on solving

kp=1.2

kd=1.4

ki=1.6