Analytical design of enhanced PID controller with set-point filter for unstable processes with time delay

Many researchers have achieved satisfactory control of unstable processes using complex control structure involving two or more PI/PID controllers. However, a simple architecture is more feasible for practical implementation. Single loop structure based control methods which are reported in literature give limited control performance for unstable plants. In this work, single loop control strategy using only one PID controller is proposed for the above said processes to meet the industrial requirement. Controller's unknowns are explicitly expressed in terms of the plant model parameters using direct synthesis approach. Suitable values of the design parameter are recommended after studying their effect on the system performance and robustness. Proposed strategy is analytical, straight forward and involves only one design parameter, and it gives improved response compared to some reported tuning methods. Also, proposed scheme yields satisfactory robustness towards process parameter uncertainties, load disturbances and noise.