Performance comparison between PID and dead-time compensating controllers

This paper is intended to answer the question: “When is a simple dead-time compensator expected to perform better than a PID?”. The performance criterion used is the integrated absolute error (IAE). It is compared for PI and PID controllers and a simple dead-time compensator (DTC) when a step load disturbance is applied at the plant input. Both stable and integrating processes are considered. For a fair comparison the controllers should provide equal robustness in some sense. Here, as a measure of robustness, the maximum of the absolute value of the sensitivity function is used. Since this is not a sufficient measure of robustness when errors in the dead time are considered, performance of the DTC's is given also as a function of dead-time margin (DM) where appropriate.