Synchronization of Fractional Chaotic Systems via Fractional-Order   Adaptive Controller
  In this paper, an adaptive fractional controller has been designed to control chaotic systems. In fact, this controller is a fractional PID controller, which the coefficients will be tuned according to a proper adaptation mechanism. The adaptation law will be constructed from a sliding surface via gradient method. The adaptive fractional controller is implemented on a gyro system to signify the performance of the proposed technique. 
S. H. Hosseinnia, R. Ghaderi, A. Ranjbar N., J. Sadati, S. Momani
nlin.CD