A unified approach of PID controller tuning for time delay processes

The motivation of this study is to obtain a single PID tuning formula for different type of processes with enhanced disturbance rejection performance. The simple tuning formula gives consistently better performance as compared to well-known SIMC method at the same degree of robustness for stable and integrating process. The performance of the unstable process has been compared with other recently published methods where it also shows significant advantage in the proposed method. For the selection of the closed-loop time constant, (τ_c), a guideline is provided for a broad range of time-delay/time-constant ratios on the basis of the peak of maximum uncertainty (M_s). The comparisons of the IAE have been conducted for a wide range of θ/τ ratio for the first order time delay processes. The proposed method gives better performances for wide range of θ/τ ratio as compared to SIMC while Lee et al. shows poor disturbance rejection in lag dominant process.