Hybrid controller for precision positioning application

In this paper, a precision positioning hybrid controller for long travel distance with submicron/nanometer resolution and accuracy is designed and developed. A hybrid control algorithm is designed to combine the coarse positioning system and a precision positioning system. The coarse positioning system consists of a linear stepper motor and coarse positioning controller, which is designed by microstepping with proportional-integral (PI) current feedback (MSPICF) control. In the precision positioning system, a piezoelectric actuator (PZA) is used. The mathematical model of the PZA has been represented by 2nd order mass-spring system with the Dahl hysteresis model and the model parameters are estimated by an autoregressive with exogenous terms (ARX) model identification technique using the input–output experimental data. The precision positioning controller designed by feedforward (FF) control which is the inverse of the mathematical model of the PZA and feedback (FB) control. The coarse, precision and hybrid controller is implemented using a low-cost DsPIC30F4012 microcontroller. Experiments have been performed to evaluate the performance of the controller.