“…It is a powerful tool to describe systems which have long-term memory and longrange spatial interaction. Fractional calculus has been applied in control theory in recent years, and there have been many theoretical achievements in controllability [1,2], observability [3,4], stability [5][6][7], robustness [8,9] and control methods [10][11][12]. At the same time, fractional order theory has also achieved great success in control engineering, such as the fractional order PID controller [13,14], air-based precision positioning system [15], fractional order positive position feedback compensator [16], and fractional order gray model [17,18].…”