Abstract
Nonlinear friction, resonant vibration modes, in addition to dead time of a positioning mechanism deteriorate the control performance in the microscopic displacement range. A control scheme composed of two types of control methodology is proposed in this paper in order to obtain high speed and high precision positioning of a ball-screw-driven mechanism: a feedforward compensator, based on coprime factorization of the positioning mechanism with dead time compensator, and a feedback compensator, an auto-tuned PDFLC (Proportional plus Derivative Fuzzy Logic Controller) based on real coded genetic algorithm as an optimization technique, with nonlinear friction compensation by using inverse model-based disturbance observer. Experimental results verified the effectiveness and robustness of the proposed control system against the difference of the nonlinear friction accompanied with the repetitive motion.
