Performance/robustness tradeoff analysis of PI/PID servo and regulatory control systems

This paper presents a performance (Integrated Absolute Error IAE) - robustness (Maximum Sensitivity M
_s
) tradeoff analysis for First-Order-Plus-Dead-Time (FOPDT) and Second-Order-Plus-Dead-Time (SOPDT) servo-control and regulatory control systems with One-Degree-of-Freedom (1-Dof) and Two-Degree-of Freedom (2-Dof) Proportional Integral (PI) and Proportional Integral Derivative (PID) controllers. Analysis shows that for same model, performance optimized 1-DoF PI controllers are more robust than the PIDs but their optimal performance is lower. The performance optimized regulatory control systems, PI and PID, are less robust than the servo-control ones, requiring also more performance degradation to reach the same robustness level.