Design of robust fractional order PI for FOPDT systems via set inversion

This paper presents a new design approach of a fractional order PI controller for uncertain system with delay. The method uses the set inversion via interval analysis approach to determine the three parameters of the controller in accordance with different frequency specifications. When applied to uncertain delay system, the method computes the interval of each parameter providing the desired performances. Some numerical examples illustrate the effectiveness of the proposed approach in the case of an uncertain first order plus dead time system.