Research on a valve-positioner pilot valve driven by a piezoelectric stack with self-sensing feedback

With the continuously increasing demands for control accuracy and response speed in automation systems, piezoelectric actuation has been widely adopted in valve control due to its high responsiveness and precise controllability. This paper proposes a flexure-hinge displacement-amplification mechanism featuring dual output ports with differential motion, which amplifies the minute displacement of a piezoelectric stack and regulates the pilot-valve opening. Furthermore, a self-sensing feedback composite controller is developed based on feedforward control and the piezoelectric self-sensing principle, improving the control accuracy of the pilot valve without introducing additional sensors. Experimental results demonstrate that the proposed self-sensing feedback composite control strategy effectively suppresses nonlinear and hysteresis errors of the valve spool, thereby enhancing the overall control accuracy of the system.