STRUCTURE AND TUNING OF OBSERVER-BASED PID

The proportional-integral-derivative (PID) is the most widely used control structure in the industry. However, due to the measurement noise, the derivative action of PID control is often ignored (PI is used instead), or a filter has to be designed together with PID, which makes the practical PID structure complex and the parameter tuning difficult. In this paper, an observer-based PID (OB-PID) control structure that utilizes a model-free observer to estimate the plant output and its derivative is proposed. Then, a parameter tuning rule is derived for the OB-PID structure using the typical first -order plus dead-time (FOPDT) model. The tuning rule considers robustness, disturbance rejection, and noise attenuation of the closed-loop system simultaneously. Simulation results show that the OB-PID can achieve good control performance and the temperature control lab experiment verifies the effectiveness of the proposed method.