Research ArticleOn the fragility of fractional-order PID controllers for FOPDT processes

•The fragility of fractional-order PID controllers is analyzed and compared to that of standard PID controllers.•Both robustness and performance fragility are considered.•It is shown that fractional-order PID controllers are more fragile and therefore more attention should be paid in their tuning.

This paper analyzes the fragility issue of fractional-order proportional-integral-derivative controllers applied to integer first-order plus-dead-time processes. In particular, the effects of the variations of the controller parameters on the achieved control system robustness and performance are investigated. Results show that this kind of controllers is more fragile with respect to the standard proportional-integral-derivative controllers and therefore a significant attention should be paid by the user in their tuning.