Gains for modified Ziegler-Nichols in AFM example don't match MATLAB

[Richard Murray]

In Example 11.4 (AFM in tapping mode), the values of the gains for the modified ZN tuning rules don’t match what MATLAB is computing and the formulas in the MATLAB file don’t match what we list in the text in equation (11.10b). We should make these all consistent.

[Richard Murray]

In looking through the changes, I went back and looked at the original Ziegler and Nichols paper. There are some inconsistencies in what we have listed versus what they have in their paper.

Frequency response method: P and PID are OK, but for PI controller they have kp = 0.45 kc, Ti = Tc/1.2=0.83Tc. Do we want to keep our values or use theirs?

[Richard Murray]

Fixed in commit d461ba2.