Two-degrees-of-freedom speed controller based on doubly coprime factorization and speed observer

This paper proposes a new two-degrees-of-freedom speed controller based on doubly coprime factorization and speed observer. The proposed system individually defines a reference response and a disturbance rejection response considering a robust stability. The free parameter Q(s) of the proposed two-degrees-of-freedom control system is defined by doubly coprime factorization and the new free parameter g(s) in this paper. In an ultra low speed range, the speed sensor based on a rotary encoder cannot detect a motor speed. In this paper, the speed information is estimated by the proposed instantaneous speed observer whose input variables are an armature voltage and an armature current. The proposed total speed control system regulates a motor speed robustly and has a desired response in the whole speed range