Design of robust high-speed motion controller for a plant with actuator saturation

A robust high-speed motion controller is proposed. The proposed controller consists of the proximate time optimal servomechanisms (PTOS) Sou high-spee d motion, disturbance observer (DOB)for robustness, friction compensator, a nd saturation handling element. In the proposed controller, DOB basically p rovides the chance to apply PTOS to nondouble integrator systems by drastic ally reducing disturbances as well as unwanted signals doe to difference be tween real system and the double integrator model. Brit, in DOB-based syste ms, if control input is saturated due to control input of PTOS and/or DOE, overall system stability cannot be guaranteed which is first found and anal yzed in this paper. To solve this problem, robust stability and internal st ability conditio,as of DOB-based sq:stern ave derived. IE is also shown tha t DOE could violate the internal stability: when the control input is satur ated Eventually, a simple saturation handling element is inserted to mainta in internal stability of overall system. Also, ne explain that our two satu ration handling methods, i.e., Additional Saturation Element (ASE) and Self Adjusting, Saturation (SAS) are the equivalent solutions of saturation pro blem to maintain internal stability: The stability and performances of the proposed controller are verified through numerical simulations and experime nts using a precision linear motor system.