On stabilization of first-order plus dead-time unstable processes using PID controllers

This paper considers the problem of stabilizing first-order plus dead-time (FOPDT) unstable processes using PID controllers. The D-partition technique is applied to characterize the stability domain in the in the space of system and controller parameters. Moreover, analytical expressions are derived for describing the stability domain boundaries. These analytical expressions can be used to construct the complete set of stabilizing PID controller parameters for both open-loop unstable time-delay processes. They can also be used to investigate the effect of time delay on the stabilizability of the process.