The Chien–Hrones–Reswick (CHR) method [66] emphasizes the set-point regulation or
disturbance rejection. In addition one qualitative specifications on the response speed and
overshoot can be accommodated. Compared with the traditional Ziegler–Nichols tuning
formula, the CHR method uses the time constant T of the plant explicitly.
The CHR PID controller tuning formulas are summarized in Table 6.2 for set-point
regulation. The more heavily damped closed-loop response, which ensures, for the ideal
plant model, the “quickest response without overshoot” is labeled “with 0% overshoot,”
and the “quickest response with 20% overshoot” is labeled “with 20% overshoot.”
Similarly, Table 6.3 is used to design controllers for disturbance rejection purposes.
A MATLAB function chrPID() is written which can be used to design different
controllers using the CHR algorithms