# HW 7 Prob 1 Comments

For Problem 1c you need to design only ONE controller (ignore the plural 'controllers' in the HW wording for 1c). The controller should be designed using the Ziegler-Nichols rules for the step response method. You need to plot the step response and the frequency response (bode plot) of your final design (i.e., the closed-loop system) You also need to compute the gain & phase margins of the loop transfer function L.

The Ziegler-Nichols step response method rules are found in Table 10.1a on pg. 301. Remember that you need to plot the unit step response for the plant. You must draw the steepest tangent line to the step response until it crosses the two axes. You can then approximate the values for "a" and "tao" by visual or numerical approximation. You might need to change the y-axis range of the plot to determine the y-intercept.

As usual for all HW questions, give a title to your plots, label axes, and turn in code along with your plots. --Soto 14:20, 25 November 2007 (PST)