Simple PID controller tuning method for processes with inverse response plus dead time or large overshoot response plus dead time

Whenever a controlled variable encounters two (or more) competing dynamic effects with different time constants from the same manipulated variable, the resulting composite dynamic behavior of this process can exhibit a troublesome inverse response or a large overshoot response. These unusual dynamic behaviors together with the process dead time can cause problems in PID controller tuning. These types of responses are observed in some particle control loops in the chemical industry or can be observed more frequently in multiloop systems. In this paper, a simple PID controller tuning method will be proposed to handle these two difficult types of control loops. The proposed tuning method is derived from a direct synthesis controller design method. Both PID and PI-only tuning rules will be proposed in this paper.