Analytical optimization of IMC-PID design based on performance/robustness tradeoff tuning strategy for the modified Smith structure

Abstract

In this paper, a modified two degrees of freedom Smith control structure is proposed to realize tradeoff tuning strategy between the dynamic performance and system robustness based on analytical optimization of internal model control proportion integration differentiation design method. By analyzing the stability performance of the modified Smith control structure, the control characteristic between the modified Smith control structure and two adjustment parameters is obtained. The different input responses are discussed based on the performance of modified control system. Moreover, the set point response and the disturbance response of the closed-loop system are adjusted by two parameters, respectively. The multiplicative uncertainty plant is imposed into the modified Smith control system to analyze the system robustness from the aspect of the structure uncertainty. The proposed control strategy is applied to the second order plus delay time plant. The simulation result reflects that the modified Smith control structure is the method which is based on the tradeoff between the performance and the robustness tuning strategy.