Robust Fractional order PI Controller for Switching Systems
  This paper is concerned with the robust design for a class of switching systems from a fractional order control (FOC) perspective. In particular, the tuning of the robust fractional order PI (RFPI) controller is proposed based on phase margin and cross over frequency specifications, ensuring the quadratic stability of the system, i.e., the third design specification is given by the stability condition. The quadratic stability is analyzed using a frequency-domain method equivalent to the common Lyapunov one. Two examples are given to show the effectiveness of the proposed controller. 
S. Hassan HosseinNia, Ines Tejado, Blas M. Vinagre
nlin.AO