PID lead-lag controller design for second order integrating unstable process

PID Lead-lag tuning formulas are derived for integrating unstable processes based on proposed modified Internal Model Control (IMC) structure. The structure extends the standard Internal Model Control structure for stable processes to unstable processes. To achieve better output response, even in the presence of load disturbance a second order low pass filter is inserted in the loop to reduced mismatch between process and model. An advantage of the structure is that set-point tracking and disturbance rejection can be easily done. Denoising methods are presented to cope with measurement noise, a first order low pass filter is inserted in the loop to denoise the output signal.