A comparison of fractional Smith predictors

A new class of fractional Smith predictors is proposed in this paper, associating Internal Model Control for the design of time delay controllers to the CRONE template in order to improve robustness to static gain variations. Numerical simulations illustrate intrinsic and structural robust performances of the fractional PI and PID predictors. Comparisons of the two controllers show that the Smith PID presents the greatest ability to reject gain variations and system structure uncertainty.