New control schemes for stick-slip micro-positioning stages

Two control algorithms are developed for micro-positioning of stick-slip actuators. By modulation of a sawtooth signal according to the error between the instantaneous value of the stage displacement and the desired reference, a precise displacement motion of the stage is realized. The applied voltage is a saw-tooth signal whose support of time is a time-varying controlled variable. The support of time of the input is calculated as an integer number that is proportional to the tracking error signal. It has been found that the proportional and the integral-control-based procedures provide satisfactory transient and steady-state behaviors of the end effector. The tracking errors, recorded during the real-time experiments, are found very acceptable when we assess the complexity of the developed controllers and the overall distance traveled by the stage.