Hybrid intelligent controller for high precision positioning mechanism

Ball-screw-driven mechanism has been used in many industrial applications. In microscopic displacement range, resonant modes, dead time in addition to nonlinear friction of this mechanism deteriorate the positioning performance. To obtain high precision response in this displacement range, a control scheme was proposed as a composition of two types of control methodology: a feedforward compensator and a feedback hybrid approach with nonlinear friction compensation using DOB (Disturbance Observer). The hybrid approach combines RCGAs (real-coded genetic algorithms) as optimization techniques to provide an automatic off-line selection for PDFLC (Proportional plus Derivative Fuzzy Logic Controller) membership function parameters. Simulated and experimental results demonstrated the effectiveness and robustness of the proposed controller.